a 


a8 ‘ 
a 


- 
Ke 
N) i A RUA Neen 
vaiald ea athe OM WN ifn et 
maT Baa ee Hy U 
4h siete e iN 
; LN viliiy 


Ag CHAN) fit vie A Wat 
AHO 


AE his " 
Yoda 
vas cy TN i {yh} Ses 194 
a ee Ne 


ee ae 
hy ( 
. oo mH 

its in is hy CaN 


‘an a oe a 


co 
ae 


ite i Ant HK} 
Nant 
” ah acid i ii ae 


ms i 
4 1M iti Hi 


Pate ele 
CRON RDG 


tt \ 
A } 
biti ye) : 


| - ne 
aN ah 
fi WYN oe iH Ny, ih 


eh 


na 


an 
i M e i 
Kh 


a , iy i) 
i aan ia 
i) ISDA 
Mair Anal Haatinieae 
ae 4 

i Wi Mi i 
Aa) HN 
au i i 


‘teh 
a 


te } 
au i} ii 


Hin i 

i i WAN Ae 1 i 
Py DHA IA ay aR se 

ic Ma Hig nh Ua CA i 

th a 


Ny) say x 

HAN veh’ ‘ 
fh y 
i i aaalul i 
Vs a eat 

4 vay 
LSM Hy at) { Hse 
Becwerr ne) 


tid RUD 
i sagt ite 

HAL 
i ih nl i ; 
nh) Ay a awa ih Ht 


CNRS 


i me 
ve HN 
He 
fee He 

oy We 


vant 
Hi ei 
a oH HN Wi ae 


sealant sy its 


a 


eat WW a iM He iH f} 
Set ioe Ni vi a 

HM) ihe it Hi HN a a i 

ce . He 
a va RR 
i) AG) OM] : 

: raha POA HON 

09 a x 

hy Wel bitin 


a ditt pie 


qh i 


5% 


a a 

Ms RNG i sity 

cin hy ay } 
Neils 


ead 
et) 


i 

i) 
A) H 
Ae i 


rai ae 

eng ats RH ia 
ta! LNs 

ma im 


in 
Hi 
o 


( 
MMe tt 


be i ey 


i Le 
a 


ne it iy oi 
one i 


" 


nek vit 


i \ i i “4 in tH a K 
GSW eet 
el Pi Hie ff nN 
i a ce , 
aan 


it 

nih 
i Heel 
itt S Bt i Haat 
Tat uy scent 


i} 
Rae rieeeateh 4 a9) nN mu 
wiv i roy s it} ay idea us i fit Res vii ae ii ie 
i vy wi WN ch ahh i : ih oo tii ie 
4 co aan i iii fs MY Ny i ie ne 
, Hi a fais 


RG + i} 
no aby cy atl AN 
mys ae AA, WF ta os Pus ait Hata 


a Onc i} Hy a os oe i 
iN “his 
4 ryt 


oe hs Rie 


ONE baie , teh 
Neate 
Aaa 
Mas oe atc ae 
ee 


LE ALA mt i 
ee se 


a 


Ni 


ai Wi 


TOMA 
ea tena 
Cena t ‘ 
NANNY apie itis 1st Vay 
HH Sih W Avo 


MPry 

AUN i 

a i ase A Re WAN 

DORON MOI { iN i i! 
; Mi OOK ai 

6 SN WA | 44; DKS i i { 

Dal ‘ Heyes f 


Ni 
fai aii 


4 run 

DORON HALAS 

1 AY, 
‘ 


W Wk get 
DTW viel 


Choy dncaw neg CA) 
CM mis aed [ 
Wael 


Ht AR 

i AAD Mt i 
WYN oh She 

Vala “a sti i K 


Med pate Went 


: \ y 
Wa} 101 its Mite Mathie ah M4 ( 
Pee wad dn 7H " Wetn ihe edu AeA yt of tet Wh ti i} 
q ) WAN UH A can A) it i Mien ath ia mi ; Nal ‘ in i vi hy at} ane Min Ni Wi ohh ae 
a a ays U ‘ cK Any wip 4 Eigse et Wh na me i aia } wih We Uh He Kins a ae — f 
\ oy ei +i 4 ijt 4 ian: A wip si 
ius CAA et CANE URSA OT RR CH Na Hi ‘i ng ‘ i) ; 


mn 
A nO 4 


3: . 
ns 
b ie aS 


f 


ree 
bx 


Cer 


Saleh. 


THE 


PORIMN AI OF GEOLOGY 


A Semi-Quarterly Magazine of Geology and 


Related Sciences. 


EDITORS 
T. C. CHAMBERLIN 

R. D. SALISBURY C. R. VAN HISE 

Geographic Geology Pre-Cambrian Geology 
J. P. IDDINGS C; 1D, WALCO 

Petrology Paleontologic Geology 
ING Yala Lt TLINIROSIS, |px W. H. HOLMES 

Economic Geology Archeologic Geology 


GEORGE BAUR 
Vertebrate Paleontology 


ASSOCIATE EDITORS 


SI ARCHIBALD GEIKIE JOSEPH LE CONTE 
Great Britain University of California 
H. .OSENBUSCH G. K. GILBERT 
Germany Washington 
CHARLES BARROIS H. S. WILLIAMS 
France Vale University 
ALBRECHT PENCK J. Cc. BRANNER 
Austria Leland Stanford, Jr. University 
HANS REUSCH G. H. WILLIAMS 
Norway Johns Hopkins University 
GERARD DE GEER I, C, IRWSSIBILIL 
Sweden University of Michigan 
GEORGE M. DAWSON O. A. DERBY 
Canada Brazil 
LIE SOS RS 
VOLUME II Zgsonian Instn 
a, “op 
1894 ( 250 p22 
let fonal Musev™: 
CHl CAG ®@ ee ae 


Che Anibersity of Chicago Press 


CON TIBNTIES OF VOLUME ff. 


NUMBER I. 


THE DISTRIBUTION OF ANCIENT VOLCANIC RoCKS ALONG THE EASTERN 
BORDER OF NorTH AMERICA; Plate I. George H. Williams. 


REVOLUTION IN THE TOPOGRAPHY OF THE PACIFIC COAsT SINCE THE 
AURIFEROUS GRAVEL PERIOD. J. S. DILLER. 


THE NAME “ NEWARK” IN AMERICAN STRATIGRAPHY: A JOINT DCE CON. 
G. K. Gilbert, B. S. Lyman. 


AN ABANDONED PLEISTOCENE RIVER Cua IN Go ane TE 
Charles’S. Beachler. i 


STUDIES FOR STUDENTS: Physical Geogaene A the University. “Wm. M. 
Davis. 2 : ; : é 0 : : ; : : 

EDITORIALS. 

REVIEWS: Riigen. Eine dineelstudie: De Rudolf creanes, By ‘iifea. M. Davis. 


ANALYTICAL ABSTRACTS OF CURRENT LITERATURE; Summary of Current 
Pre-Cambrian North American Literature. F i é : : 


ACKNOWLEDGMENTS. . 5 5 


NUMBER II. 


THE GLACIAL SUCCESSION IN NoRWAY. Andr, M. Hansen. P : 

Duat NOMENCLATURE IN GEOLOGICAL CLASSIFICATION. ie Shaler 
Williams. f 3 

ORIGIN AND Cauca euniON « OF THE GRraNcnns OF New. fee Wil- 
liam Bullock Clark. F ; 3 

THE NATURE of COAL HORIZONS. Chenies Rollin Keyes! : : ' 

THE ARKANSAS COAL MEASURES IN THEIR RELATION TO THE Becieie 
CARBONIFEROUS PROVINCE.- James Perrin Smith. 

PsEUDO-CGots.: T. C. Chamberlin. - : 5 : . ; ‘ 

NOTE ON THE ENGLISH EQUIVALENT OF SCHUPPENSTRUKTUR. William H. 
Hobbs. 

GEOLOGICAL SURVEYS IN aecOuEE: Nettie Wimalor, 

EDITORIALS. — 

REVIEWS: The HoonomieGeclonyot Ihe United States, IR S, Tess, by R. Ac 
F. Penrose, Jr.; The Canadian Ice Age, Sir J. William Dawson, by T.C. 
Chamberlin ; ‘The Post-Pliocene Diastrophism of the Coast of South- 
ern California, Andrew C. Lawson, by Rollin D. Salisbury. 

ANALYTICAL ABSTRACTS OF CURRENT LITERATURE: Ein typisches Fjord- 
thal, Erich yon Drygalski; A Preliminary Report on the Cretaceous 
and Tertiary Formations of New Jersey, William Bullock Clark; The 
Pleistocene Rock Gorges of Northwestern Illinois, Oscar H. Hershey; 
Notes on the Sea-Dikes of the Netherlands, Professor Ge Smock. 

ili 


107 


109 
119 


123 


145 


161 
178 


187 
205 
206 
207 
222 


. 226-235 


239-241 


iV CONTENTS OF VOLUME I]. 


NUMBER III. 
THE OIL SHALES OF THE SCOTTISH CARBONIFEROUS SYSTEM. Henry M. 
: Cadell. ‘ a 5 ; 6 5 
THE CRETACEOUS RIM OF THE BiAee mere Lester F. Ward. 
ON DIPLOGRAPTIDA, LAPWORTH. Carl Wiman. 
GEOLOGICAL SURVEYS IN ALABAMA. Eugene Allen Smith. 
THE SUPERFICIAL ALTERATION OF ORE Deposits. R. A. F. Penrose, Jr. 


STUDIES FOR STUDENTS: Erosion, Transportation and Sedimentation Per- 
formed by the Atmosphere. J. A. Udden. 


EDITORIALS. 


REVIEWS: Geological cian of ‘Conia, J. W. Saencer by a Smith ; 
Annual Report of the Geological Survey of Arkansas for 1890. Vol. 
IV., Marbles and other Limestones, T. C. Hopkins, by R. A. F. Pen- 
rose, Jr. : ; : ; A ‘ 5 é , 
ACKNOWLEDGMENTS, 


NUMBER IV. 


THE NORWEGIAN COAST PLAIN. Hans Reusch. 

GLACIAL CANONS. W. J. McGee. : 5 

FossIL PLANTS AS AN AID TO GEOLOGY. F. i. KRHOeIOn. : . 
WAVE-LIKE PROGRESS OF AN EPEIROGENIC UPLIFT. Warren psitesi, 


THE OCCURRENCE OF ALGONKIAN ROCKS IN VERMONT AND THE EVIDENCE 
FOR THEIR SUBDIVISION. Charles Livy Whittle. 


EDITORIALS. ‘ : 


REVIEWS: The Datayette Fonnaton Ww. Yo McGee: ya Ww. Shenton. Ele- 
mentary Meteorology, William Morris Davis, by H. B. Kimmel. 3 


ANALYTICAL ABSTRACTS OF CURRENT LITERATURE: Summary of Pre- 
Cambrian North American Literature. C.R. Van Hise. : 


NUMBER V. 


THE ORIGIN OF THE OLDEST FOSSILS AND THE DISCOVERY OF THE BOTTOM 
OF THE OCEAN. W. K. Brooks. : 5 ; 5 : . 0 


THE AMAZONIAN UPPER CARBONIFEROUS FAUNA. Orville A. Derby. 
GEOLOGICAL SURVEYS OF OHIO. Edward Orton. : : 0 


STUDIES FOR STUDENTS: Proposed Genetic Classification of Bieiracene 
Glacial Formations. T. C. Chamberlin. 


EDITORIALS. A ; ; 


REviEws: The Iron-Bearing Rowks ae the “Mesabi Rancen in Minnesot Yo 
Edward Spurr, by T. C. Hopkins; The Mineral Industry: Its Statistics, 
Technology, and Trade in the United States and other Countries, etc. 
T. C. Hopkins. ; . 0 : : : . : 


NUMBER VI. 


THE CENOZzoIC DEposiITs OF TEXAS. E. T. Dumble. > 


OUTLINE OF CENOZOIC HISTORY OF A PORTION OF THE MIDDLE AA aNe IC 
SLopE. N. H. Darton. 


THE METAMORPHIC SERIES OF ee Coney © Gite Eee Per- 
rin Smith. 


STUDIES FOR STUDENTS: Superglacial Drift. Rolle D. Sarepury 
EDITORIALS. : . . : . : : 


- 335-339 


342 


347 
350 
365 
383 


396 
430 


435-440 


444 


455 
480 
502 


517 
539 


. 545-546 


549 
568 


588 
613 
633 


CONTENTS OF VOLUME 1. 


REVIEWS: Some Recent Alpine Studies. “Gy P: Grimsley. 

ANALYTICAL ABSTRACTS OF CURRENT LITERATURE: Eastern Boundary of 
the Connecticut Triassic, W. M. Davis and L.S. Griswold; Some New 
Red Horizons, B.S. Lyman; Minerals Found in Building Stones, Lea 
MclI. Luquer; Landscape Marble, Beebe Thompson; Connecticut 
Brownstone, B. H. Allbee; Lake Superior Sandstones, H. G. Rothwell ; 
The Great Bluestone Industry, H. B. Ingram. 3 


NUMBER VII. 


GLACIAL STUDIES INGREENLAND. I. T.C. Chamberlin. . 
On A Basic RocK DERIVED FROM GRANITE. C. H. Smyth, Jr. 
THE QUARTZITE TONGUE AT REPUBLIC, MICHIGAN. H.L. Smyth. 
A SKETCH OF GEOLOGICAL INVESTIGATION IN MINNESOTA. N. H. Winchell. 
STUDIES FOR STUDENTS: The Drift—Its Characteristics and Relationships 
(continued). Rollin D. Salisbury. 5 : : 
EDITORIALS. 5 . : 
REVIEWS: The Great Tee Age: james Geikie, by Rollin D. Satousts : Papers 
and Notes on the Glacial Geology of Great Britain and Treland, H. C. 
Lewis, by T. C. Chamberlin; The Colorado Formation and its Inverte- 
brate Fauna, T. W. Stanton, by H. F. Bain.. 
ANALYTICAL ABSTRACTS OF CURRENT LITERATURE: The Reladen iiaeen 
Baseleveling and Organic Evolution, J. B. Woodworth; Tertiary and 
Early Quaternary Baseleveling in Minnesota, Manitoba, and North- 
westward, W. Upham; Proof of the Presence of Organisms in Pre- 
Cambrian Strata, L. Cayeux; The Niobrara Chalk, Samuel Calvin; A 
Study of Cherts in Missouri, E. O. Hovey. 0 . 


RECENT PUBLICATIONS. 


NUMBER VIII. 


GEORGE HUNTINGTON WILLIAMS. J. P. Iddings. 

GLACIAL STUDIES IN GREENLAND. II. T.C. Chemabsaiits 0 

A PETROGRAPHICAL SKETCH OF AIGINA AND METHANA. Pilate III. 
Henry S. Washington. 6 0 . 

THE Basic MASSIVE ROCKS OF THE DAKE Spann RESON. W.S. Bay- 
ley. : : : 

THE GEOLOGICAL Stes OF A aiecn: Ik G Benen 

STUDIES FOR STUDENTS: The Drift—Its Characteristics and Relationship 
(continued), Rollin D. Salisbury. 

EDITORIALS. 

REVIEWS: Hussak’s Geology of the Intenion a Beart Ih C. Branner: 
Einleitung in die Geologie als historische Wissenschaft, J. Walther, 
by E.C. Quereau; Geologische und geographische Experimente, Heft 
IlI., Rupturen, Heft IV. Methoden und nee E. roe by E. C. 
Ouereau. 

ANALYTICAL Anemone OF Conn LapRAT Re veda der Ground: 
Expedition der Gesellschaft fiir Erdkunde, Dr. Erich von Drygalski; 
The Geology of Angel Island, F. L. Ransome; Geological Survey of 
Missouri: Bevier and Iron Mountain Saas, C. H. Gordon, ef a/.; 
The Granites of Cecil County, Maryland, G. P. Grimsley ; Erosion 
in the Hydrographic Basin of the Arkansas River, J. C. Branner; 
The Tertiary Geology of Southern Arkansas, G. D. Harris. 

RECENT PUBLICATIONS. : 6 3 : 

INDEX. . c ; . 


639 


. 644-647 


649 
667 
680 
692 


708 
725 


- 730-751 


- 753-756 


757 
759 
7608 


789 


814 
826 


837 
852 


. 853-862 


. 863-867 
868 
871 


aN 


PLA Beadle 


ReGEOLs VoL Li, msoq: 


~ 


= 
x 
= 
= 
as 
A 


MAP 
SHOWING THE 
KNOWN AND PROBABLE 
OCCURRENCES OF 
ANCIENT VOLCANIC ROCKS 
IN EASTERN NORTH AMERICA 
BY 
GEORGE HUNTINGTON WILLIAMS 
1893. 


Gl] PROBABLE 


Ga KNOWN 
Benedict & Co., Engr’s, Chi. 


THE 


LOGIN A OF GEOLOGY 


VELNOATRY BE BTC AVE TSO. 


Eee DiS tel BUMION Ob (ANCIENT VOLCANIC ROCKS 
AUCOUNG: Isis, JONSINSIRIN JORDI Ole 
NORTH AMERICA:* 


CONTENTS. 


INTRODUCTION. 
Diversity of Opinion regarding Ancient Volcanic Rocks. 
Great Britain. 
Germany. 
Belgium and France. 
Scandinavia. 
Russia. 
America. 
Criteria for the recognition of Ancient Volcanic Rocks. 
Distribution of Volcanic Areas in Eastern North America. 
Eastern Canada (Newfoundland, Cape Breton, Nova Scotia, Gaspé, New 
Brunswick, Eastern Townships). 
New England States (Maine, New Hampshire, Massachusetts). 
Middle Atlantic States (New York, Pennsylvania, Maryland, Virginia). 
Southern States (North Carolina, South Carolina, Georgia, Alabama). 


General Conclusions. 


THE great crystalline belt of the Eastern United States and 
Canada, in spite of all the attention it has received, is probably 
still the least understood geological province of our continent. 
Here, almost more than anywhere else, personal adherence to 
some preconceived theory of the origin and relationships of rocks 
has biased observation and led to contradictory or unsatisfactory 

«This paper was outlined at the International Geological Congress in Chicago, 
August, 1893, and read in full before the Geological Society of America at its Boston 


Meeting, December 28, 1893. 
VoL. II., No. 1. I 


2 THE JOURNAL OF GEOLOGY. 


interpretations of the facts. Only within recent years has 


detailed and independent work been undertaken in widely sepa- 


rated parts of this vast area, and as yet no sufficient data is at 
hand for structural, or even for petrographical correlation 
throughout the whole. 

Complete geological maps, showing the structural relations 
and chronological sequence of all the crystalline formations, are 
undoubtedly what must be looked forward to as the ultimate aim 
of work within this region, but the most sanguine will surely 
admit that we are at present a long way from any such reality. 
Meanwhile, in the absence of paleontological evidence, the study 
of the rocks from the point of view of genesis and the establish- 
ment of petrographic correlations will do much toward furnish- 
ing the positive basis of knowledge upon which final solution of 
complex structure must rest. 

Some of the notions regarding petrographic sequence and 
the origin of foliation, enforced by masters of geology high in 
authority, have obscured rather than advanced the problems pre- 
sented by the crystalline rocks in eastern North America. Not 
only have we been taught that the mineralogical and structural 
characters of these rocks are safe indices of their superposition 
and relative age, but the interpretation of all parallel structures 
as proofs of sedimentation has led to the conclusion that igneous 
rocks are rare, if not altogether absent, in these oldest and gen- 
erally foliated formations of the earth’s crust. Now, however, 
better conceptions are beginning to prevail. No longer do we 
regard the petrographic character of a crystalline rock as any 
criterion of its age, while modern methods have enabled us to 
identify the abundant igneous rocks of ancient times in spite 


of the misleading structures imparted to them by secondary- 


causes. 
Olject of this pauper. 


occasion to insist on the presence of such disguised igneous 


The present writer has had frequent 


masses in the oldest geological formations, and to dwell upon 
the methods by which their origin may be established. In the 
present paper it is his object to show that not only igneous, but 


LTE DT SILABOTLON OLR ANCIENT, VOLGANTC ROCKS. 3 


also volcamc* rocks are widely distributed through the crystalline 
belt of eastern North America, and to direct attention to them as 
offering a new and promising field for work in crystalline geol- 
ogy. For the accomplishment of this purpose it will be neces- 
sary (1) to consider the general attitude of geologists in differ- 
ent countries toward ancient volcanic rocks; (@ to specify the 
criteria available for their identification; and (3) to summarize 
our present knowledge of where such rocks certainly or probably 
Saisie udcmeastennn chy stallime belt lhe ematerial embraced 
under the third of these heads has been obtained from personal 
work in the field, from a careful study of existing literature, and 
from unpublished observations and-hints furnished by friends.? 
It is hoped that the bringing together of what is now known 
of the distribution of ancient volcanic rocks in eastern North 
America, with the addition of new areas and indication of locali- 
ties where they may be looked for, will stimulate further work 
in widely separated portions of this interesting field. These 
rocks have, it is true, already been correctly described at a few 
isolated points, but no attempt has before been made to connect 
such areas or to show their probably widespread distribution. 
The recent identification by the writer of a very extensive devel- 
opment of pre-Cambrian lavas and volcanic tuffs and breccias in 
the South Mountain of southern Pennsylvania and Maryland3 
*The term volcanic might perhaps be applied with propriety to all rocks pro- 
duced in or on a volcano, without regard to their structure or coarseness of grain. It 
is, however, here employed only for effusive or surface igneous rocks, in contrast to 


such as have solidified beneath the surface, either as the basal portions of volcanoes, 
or as dykes, sheets, laccolites, or stocks (bathylites). 

2 The writer is especially indebted for help to Professor Eugene Smith, of Ala- 
bama; Professor W. S. Bayley, of Waterville, Me.; Professor J. A. Holmes, of North 
Carolina; Professor H. D. Campbell, of Lexington, Va.; Dr. A. C. R. Selwyn, of 
Ottawa; Mr. L. V. Pirsson, of New Haven; Professor S. L. Powell, of Newberry, 
South Carolina, and Mr. Arthur Keith, of Washington. The “ Azoic System” of 
Whitney and Wadsworth, and Professor Van Hise’s Correlation Essay on the Algon- 
kian have also proved of much service. 

3 Am. Jour. of Science (3d ser.), Vol. 44, p. 495, Dec., 1892. These rocks have 
been thoroughly studied by Miss Florence Bascom, whose results may be expected soon 
to appear in full and adequately illustrated form. See also this Journal, Vol. 1, No. 8, 
Dec., 1893. 


4 THE JOURNAL OF GEOLOGY. 


naturally suggested a comparison of these rocks with those of 
similar character in the Boston basin and eastern Canada, as well 
as a further search for other regions of the same kind. This 
search has already proved successful in North Carolina and 
Maine, while an examination of the older literature indicates 
many other places where a recurrence of like conditions may be 
confidently expected. 

The proper interpretation and areal mapping of all the 
demonstrably volcanic regions in the Appalachian crystallines 
will not only afford much material of interest in the study of 
petrography and dynamometamorphism, but will also contribute 
to the differentiation and final understanding of the vast belt of 
diverse crystalline rocks to which they belong. 


' DIVERSITY OF OPINION REGARDING ANCIENT VOLCANIC ROCKS. 


There is notable in the different countries where geology 
is cultivated a wide diversity of opinion regarding ancient vol- 
canic rocks. In some regions such rocks have been entirely 
overlooked or else misinterpreted ; in others they are recognized, 
but are conceived as having been formed under circumstances so 
different from those which now obtain that they are genetically 
and inherently distinct from the products of modern volcanoes ; 
in a few only are they considered as having been origin- 
ally identical with recent effusive rocks, and as differing from 
them only in alterations due to subsequent causes. This diver- 
sity of opinion may be accounted for in part by the varying state 
of preservation of ancient volcanic material in different parts of 
the earth’s surface or by the lack of experience of field geolo- 
gists with the characteristic features of modern lavas. It is, 
however, also due in a measure to the persistence of certain 
ideas promulgated by early masters of the science in their 
respective lands. 

It was in Great Britain that the real nature of ancient volcanic 
products received its earliest and fullest recognition. In spite 
of the absence of active volcanoes from the islands, these rocks 
have from the earliest days of geological inquiry been favorite 


LDU EOL ON NOT AN CIENT: VOLCANIC ROCKS. 975 


subjects of investigation. From the first, their essential identity 
with modern volcanic products has been clearly recognized and 
repeatedly insisted upon—something which we may attribute to 
the doctrines of Hutton and to the uniformitarian principles of 
Lyell. Such geologists as Scrope, de la Beche, Sedgwick, 
Murchison, Jukes, Lyell and Ramsay, speak continually of lava- 
flows, tuffs, breccias and ash-beds ina way that implies no doubt 
in’their minds as to the existence of volcanoes like those now 
active, in Paleozoic and pre-Paleozoic times. And more 
recently the delicate methods of modern petrography have in the 
same country been first made to establish the identity between 
ancient volcanic rocks and those of the present. The world is 
now but beginning to follow in this respect the lead set by 
Allport, J. A. Phillips, Judd, Bonney, Rutley, Harker, Cole and 
others in Great Britain. A few Englishmen, like Mallet or 
Hicks, have considered the oldest volcanic rocks either as orig- 
inally different from those now produced, or as characteristic of 
some definite geological horizon, but, on the whole, the British 
school of geology, more than any other, recognizes a practical 
uniformity in the nature of volcanic action and products from the 
Archean to the present." 

In Germany and France volcanic rocks (Evrgussgesteine) are 
recognized as abundant in certain of the earlier geological form- 
ations. Nevertheless there is in these countries a prevailing ten- 
dency to separate Tertiary from pre-Tertiary rocks of this class 
as things originally and genetically distinct.* It is noticeable 
that the earlier schemes of rock-classification, like those of 
Brongniart, Hatty, Cordier and K. C. von Leonhard, are quite 
purely mineralogical. The division of older and younger, or 
paleo- and neo-volcanic rocks is to be in part accounted for by 
the concentration of these masses in central Europe within the 
Permo-Carboniferous and Tertiary periods and their comparative 


tSee “The History of Volcanic Action in the Area of the British Isles,” Presiden- 
tial Address by Sir ARCHIBALD GEIKIE, F.R.S., etc.. Quart. Jour. Geol. Soc., Vols. 47 
and 48, 1891-2. 

?RoTH: Sitzber. Berl. Ak. 1869, p. 72, e¢ seg. ZIRKEL: Lehrbuch der Petro- 
graphie, 2d. ed., Vol. I., p. 838, 1893. 


6 TALE OOK MALY ORANG OLO GW: 


rarity in Mesozoic times. It is, however, also connected with 
the Wernerian doctrine of the non-recurrence of certain physical 
conditions in the earth’s development, as contrasted with the 
uniformitarianism of Hutton and Lyell. The absence of vol- 
canic types in Europe which serve to bridge over the sharp 
contrast between those of the Carboniferous and Tertiary, 
is being rapidly compensated by the discovery of such rocks in 
other regions. Fortunate finds of even pre-Cambrian lavas so 
perfectly preserved as to demonstrate their practical identity, 
both chemically and structurally, with recent products is tending 
to weaken the old distinction on the continent. There are now 
many signs of progress toward the idea that the characters 
regarded as belonging peculiarly to the older effusive rocks are 
better explained through changes subsequent to their solidifica- 
tion. 

Thus Ludwig in 1861," Vogelsang in 1867,? and Lossen in 
1869,3 regard some quartz-porphyries as only devitrified glasses, 
identical with those of modern volcanic regions; Kalkowsky,‘ 
and recently Sauer5 and Vogel,° have also brought convincing 
proof that such is often the case. 


Giimbel says: ‘‘Es scheint in dieser Beziehung denn doch eher gerecht- 
fertigt, zundachst das petrographisch Gleiche auch gleich zu bezeichnen, als in 
einzelnen Fallen ein neues Princip, das des A@fers, in die Petrographie einzu- 
fiihren, welches bei den meisten iibrigen Fallen nicht verglichen und beriick- 
sicht werden kann;’’7 


And Rosenbusch also remarks : 
“Man hat den geologischen Alter der Eruptivgesteine bisher ein héheres 


bestimmendes Moment fiir die structurelle und mineralogische Ausbildung 
dieser zugeschrieben als demselben in Wirklichkeit zukommt.’* 


*Erl. z. geol. Karte Hessens, Bl. Dieburg, p. 56, 1861. 

? Philosophie der Geologie, pp. 144-146, 1867. 

3 Abh. Berl. Ak., 1869, p. 85. 

4 TSCHERMAK’S Min. Mitth, pp. 31 and 58, 1874. 

5 Erl. zur geol. Specialkarte Sachsens, Bl. Meissen, pp. 81-91, 1889 
© Abh. geol. Landesanstalt von Hessen, vol. ii., p. 38, 1892. 

7 Grundziige der Geologie, 1888, p. 85. 


® Die massigen Gesteine, 2d. ed., 1887, p. 4. 


REO ST eh CMON TOLMAN CLEINE VOEGCANTC ROCKS. 7, 


He nevertheless adheres to the division between paleo- and 
neo-volcanic rocks, although he says that about their only differ- 
ence is that the latter can often be found to belong to volcanoes 
(2. e., volcanic mountains) which are themselves so extremely 
subject to removal by erosion.? 

Admirable observations on the use of age in rock-classifica- 
tion are made by M. Neumayr. He says: 


“Wohl muss der Geolog dem Alter der Gesteine Rechnung tragen, aber 
diese Beriicksichtigung ist eine von der Beschreibung und Ejintheilung der 
Gesteine durchaus unabhangige Sache. Wie schon oft betont worden ist, ist 
unter den Sedimentargesteinen das richtige Prinzip schon durchgefiihrt, 
dass man von Kalken, von Dolomiten, Sandsteinen, etc., des Silur, des Jura, 
des Tertiair spricht, ohne die verschiedenalterigen Gesteine von gleicher 
Beschaffenheit mit eignen Namen zu belegen; genau in derselben Weise 
wird man auch mit den Massengesteinen verfahren miissen. Auf einen 
solchen Standpunkt wird und muss die Gesteinslehre ebenfalls gelangen ; sie 
wird ihre Unterscheidung der Felsarten nur nach petrographischen Merk- 
malen und petrographischer Methode vornehmen, und die Altersbestimmung 
der Geologie iiberlassen, was natiirlich nicht ausschliesst, dass beide Forschungs- 


Yo 


gebiete von einer und derselben Person beherrscht werden. 


In Belgium we see de la Vallée Poussin in 1885 writing of 
‘Les anciennes Rhyolites dites Eurites,”3 just as they would in 
England ; while in France the recognized leader in petrograph- 
ical usage, Michel-Lévy, although he still distinguishes ‘“‘ voches 
porphyviques ante-tertiaires,’ from “roches trachytoides tertiaires et 
post-tertiaires,’ expresses himself in regard to the futility of the 
age distinction in rock nomenclature as follows : 

“On voit, par tout ce qui précéde, qu'il est nécessaire d’asseoir une Classi- 
fication pétrographique rationnelle sur des faits contingents, indépendents 
d’hypothéses géogénétiques, et que la considération de l’age des roches, a ce 
point de vue, est aussi hypothétique que celle de leurs conditions de gisement 
dans les profondeurs ou 4 la surface. Etant donné un échantillon de pro- 
venance inconnue, il est indispensible et il est possible de le nommer et de le 
décrire sans amphibologie. Il n’est possible d’en déterminer, avec certitude 
et précision nile gisement ni l’age géologique.’* 

2 M05, jos Ob 

2Erdgeschichte, Vol. 1, p. 599. 

3 Bull. de l’Acad. roy. de Belgique (3) Vol. 10, No. 8, 1885. 


4 Structures et Classification des Roches Eruptives, p. 34, 1889. 


8 THE fLOUKNAL OF GHOLO GME 


In Scandinavia, if we judge from the most recent publica- 
tions, there is, in spite of the general adherence to German 
nomenclature, a fuller recognition of the similarity between 
ancient and modern volcanic rocks than is to be found in any 
other part of Europe except England. 

On the western coast of Norway, Reusch describes old lava 
flows of quartz-porphyry and more basic diabase amygdaloids 
which show spheroidal parting on a large scale due to cooling. 
These rocks are accompanied by tuffs and breccias which, in 
spite of subsequent dynamic action, still show their original 
characters.) wim one case, on) the*islandvors Gijeimins,occunsmd 
deposit of pumice bombs cemented by what is now a chlorite 
schist.” 

In Sweden Hégbom describes the general distribution of 
post-Archean (Algonkian ) eruptive rocks, many of which bear 
unmistakable evidence of volcanic character.2 Otto Norden- 
skjold assigns the beautiful flow-porphyries and amygdaloids of 
the Elfdalen region to the same horizon, while he concludes that 
most of the HAalleflintas of southeastern Sweden (Smaland) are 
surface lavas. He finds in them such well-developed fluidal, 
eutaxitic, rhyolitic and perlitic structures that they may be 
regarded as old rhyolites or devitrified obsidians.3 The probably 
much younger and still glassy rhyolites of the gneiss area of 
Lake Mien are described by N. O. Holst.‘ 

In Russia Tschernyschew describes from the central Urals 
many types of eruptive rocks, and among them both acid and 
basic volcanics of great antiquity, accompanied by their agglom- 
erates, breccias and tuffs.5 

In America the recognition of the true character and relation- 
ships of ancient volcanic rocks has been greatly retarded both 


tBommeloen og Karméen, pp. 109, 122, and 403, 1888. 

2 Geologiska Foren. i Stock. Foérh., Vol. 15, p. 209, 1893. 

3 Bull. geol. Soc. Upsala, Vol. 1, Nos. 1 and 2, 1893. 

4 Afhandl. Sverig. geol. Undersok. Ser. C, No. 110, 1890. 

5 Allgemeine geologische Karte von Russland, Bl. 139, Central Urals. Text 4° 
Pp. 323 and 333, 1889. 


TT 2 OL STM OLMON NORA NCIENT 'VOLGANIG ROGCKKS. 9 


by the adherents to the so-called metamorphic school, like Dana, 
Logan, Rogers, Lesley and Winchell, who fail to find among 
the ancient foliated crystallines anything beside altered sedi- 
ments, but perhaps even more by the influence of that most 
extreme of all Wernerians, Dr. T. Sterry Hunt. While antithet- 
ically opposed to the members of the metamorphic school in his 
notions of lithological character as an index of geological posi- 
tion, Dr. Hunt had in common with them the conviction that the 
ancient lavas and volcanic breccias, tuffs and ash-beds were 
normal aqueous deposits. The basic volcanics of eastern North 
America enter so argely into his ‘ Huronian,” and the acid 
types so largely into his ‘‘ Arvonian,” that his writings may still 
be used as suggestive of localities where ancient effusive rocks 
may be sought for.t 

But there have not been wanting those among the earlier 
American geologists who have clearly recognized the igneous 
members of the ancient crystalline formations, in spite of their 
disguised character. Prominent among them are E. Hitchcock, 
Emmons, Lieber, Foster and Whitney. Not only the igneous, 
but the volcanic (surface ) character of the Lake Superior lavas 
has been maintained by Pumpelly,? Wadsworth,3 Irving, Van Hise® 
and the present writer.°. In Canada igneous rocks have always 
been regarded abundant in the oldest formations, while the 
volcanic character of some of them has been insisted on by 
Selwyn? and mentioned by other members of the Canadian Geo- 
logical Survey. A looseness of usage is, however, observable in 
some of these reports, where ‘‘ volcanic” is made synonymous 

*See: Presidential Address, Am. Assn. Ady. Sci., 1871; Proc. Am. Assn. Adv. 
Sci., 1876, p. 211-211; Azoic Rocks, 1878; Am. Jour. Science, May, 1880; Mineral 
Physiology and Physiography, Chap. IX., 1886. 

? Geology of Michigan, Vol. 1, 1873. 

3 Bull. Mus. Comp. Zo6l., Vol. 7, p. 111, 1880. 

4Monograph V., U. S. Geological Survey, 1883. 

5 Bull. Geol. Soc. Am., Vol. 4, p. 435, 1893. 

© Bull. U. S. Geol. Surv., No. 62, p. 192, e¢ seg., 1890. 


7 Report of the Geol. Survey of Canada for 1877-78. A, p. 5. Trans. Roy. Soc. 
of Canada, Vol. I, p. 10, 1882. 


10 THE JOURNAL OF GEOLOGY. 


with “igneous.” * In the eastern United States Wadsworth was 
the first to declare for the volcanic origin of the felsites and 
tuffs in the Boston basin which, through the influence of Hunt’s 
doctrine had, after Hitchcock’s time, come to be explained as 
sediments. To Dr. Wadsworth also belongs the honor of having 
been the first geologist on this continent to insist on the original 
identity of these old lavas and pyroclastics with the recent vol- 
canic rocks of the Cordilleras.2 There is little doubt that the 
finely preserved ancient volcanic material in the eastern crystalline 
belt and elsewhere will, when it is adequately studied, finally 
bring to this opinion most American geologists. If we as yet 
know little of the extent and distribution of our ancient volcan- 
ics, we are at least bound by no traditions to artificial and useless 
age distinctions, and may freely follow the lead of our English 
colleagues. 


CRITERIA FOR THE RECOGNITION OF ANCIENT VOLCANIC ROCKS. 


It is a self-evident proposition that the identification of 
certain rocks as volcanic products is in no way dependent upon 
their present association with a recognizable crater or volcanic 
mountain. By volcanic rocks we understand igneous or pyro- 
clastic material which has solidified or been deposited at, or very 
near the earth’s surface. It is of little moment whether or not 
it was ever piled into conical mountains. That the rocks them- 
selves bear witness to their origin and conditions of formation is 
sufficient. The successive effects of erosion on the easily removed 
volcanic mountains has been so often graphically described? that 
no further reference to the subject is here necessary. If the 
Eocene or Triassic volcanoes. have so disappeared as to leave 


'For instance, Ells in his “Geology of the Eastern Townships” (Can. Rept. for 


t) 


1886, J.) speaks of pre-Cambrian rocks as “volcanic” and “plutonic,” but enumerates 


only granite, diorite and serpentine. 1 

2Bull. Mus. Comp. Zodl., Vol. 5, 1879, p. 277 ef seg., and Azoic System, ib., Vol. 7, 
1884, p. 429. 

3See, DE LA BECHE: Geological Observer, pp. 526-537, 1851. M. NEUMAYR: 


Erdgeschichte, Vol. 1, pp. 202-204, 1887. W.M. Davis: “The Lost Volcanoes of 
Connecticut,” Popular Science Monthly, Dec., 1891. 


TELS, SONS TOROS OICMOUN MOVE SINKS TBINTR VA OIE EZAING KE TROXOIEG SS, 


only traces of their original forms, what may we expect of those 
of Paleozoic or Archean times? 

On the other hand, the association-in dissected volcanic 
regions of the effusive rocks with correspondingly abyssal types 
naturally suggests that volcanoes may have once surmounted 
many areas of coarsely granular ancient igneous rocks. As this, 
however, cannot be proved, only such regions are here con- 
sidered as yield rocks of unmistakably surface origin. 

Again, ancient volcanic rocks may have been subjected to 
metamorphosing processes severe enough to have destroyed 
most of their original characters. In such cases, patient study 
and a careful weighing of all evidence is necessary to decide 
their origin, and even that may not avail. Igneous rocks may 
be so altered as to be indistinguishable from metamorphosed 
sediments, but it many cases where this at first appears to be the 
fact, some decisive clue may be discovered. 

In establishing the volcanic nature of rocks occurring in 
ancient and more or less crystalline terrains, attention must be 
given to several different sets of characters. The field relations 
must be carefully studied and the material collected on the spot 
and afterward studied in the laboratory. The criteria for decid- 
ing on their igneous and volcanic origin may be arranged as 
follows : 

I. If the rocks are zgneous, whether abyssal or surface, they 
will: 

1. Conform in chemical composition to certain well 
established types ; 

2. Show an association of petrographical types which, 
both chemically and mineralogically, follow the laws 
of consanguinity. 

I]. If they are volcanic : 

1. They may be found in the field to occur in distinct 
sheets, flows or necks; 

2. They will have produced very little or no contact 

action jn the adjoining rocks ; 
. They may include irregular fragments of other rocks. 


Oo 


[2 


LS TLE Sf OOKLA LES OL GTR OL OG NA 


Me it they “ane woleanre 
1. They may appear to be striped, banded, or pseudo- 

“stratifed’’ conformably to adjoining sedimentary 

deposits ; 

2. They will probably be accompanied by fragmental 
(pyroclastic) material, which may or may not itself 
be really stratified. Such material will vary greatly 
in coarseness, containing bombs, agglomerates, brec- 
clas, tuffs, sands and ashes. The characteristics of 
tMmeseraner: 

1) indiscriminate mixture of all sizes and shapes of 
fragments ; 

2) material of same kind as the igneous rocks; 

3) cement, either finer fragmental material (tuff- 
breccia) or lava (flow-breccia) ; 

4) very angular shape of smallest fragments (micro- 
scopic glass sherds). 

5) if ancient volcanoes were on the shore-line, such 
material may have been immediately worked over 
by water and interbedded with more or less 
normal aqueous sediments. 

IV. Most important of all, however, is the identification of 
those characteristic structures known to originate only 
in glassy, half-glassy or very fine grained porphyritic 
rocks, solidifying at the surface, or in very narrow dykes 
where solidification has been rapid. These will be found 
to be very persistent and can usually be identified under 
the microscope in spite of devitrification, alteration, or 
even a considerable degree of dynamometamorphism. 
The most common of these structures are: 

I. a vesicular, scoriaceous, pumiceous or amygdaloidal 
structure ; 

2. a sharply defined, small porphyritic structure with a 
glassy, hali-glassy or felsitic (cryptocrystalline) base ; 

3. a spherulitic structure, due to either large or small 
lithopysee, hollow spherulites, or compact spherulites, 


TTL ESTA GTLONR OL AUNCLEN TG VOLECANIEG ROCKS) 3 


arranged either irregularly, or in more or less discon- 
tinuous bands or layers ; 

4. a flow structure, produced either by the elongation of 
vesicles or the parallel arrangement of constituents 
or crystallites. It may also be produced by the 
interlacing of different colored magmas (eutaxitic 
structure) ; 

5. corroded phenocrysts, quartz with embayments, or 
skeleton crystals due to rapid and imperfect growth; 

6. microscopic spherulites, globulites, trichites, crystal- 
lites, real or devitrified glass inclusions, quartz with 
orientated siliceous aureoles, axiolites, etc.; 

7. perlitic structure, wholly or partly devitrified. 

Although some of these structures may occasionally occur in 
dykes or other igneous rocks which have rapidly solidified beneath 
the surface, they are nevertheless so essentially characteristic of 
effusive lavas, that, in lack of any evidence to the contrary, they 
may be regarded as fairly safe guides in establishing the effusive 
nature of rocks. This evidence is beyond doubt, if such rocks 
are accompanied, as they generally are, by ash material. 

While a single one of these characteristics may not be suffi- 
cient to identify a volcanic occurrence, many, if not all of them, 
will be found to occur together, and only in rare instances will 
it be found that some of them, at least, have not survived the 
vicissitudes of metamorphism. That many regions in the ancient 
crystalline belt of the Appalachian system exhibit most of them 
in great perfection is now well known. It is only a misinterpre- 
tation of these characteristic features of volcanic rocks, due to 
a lack of acquaintance on the part of observers with their recent 
analogues, that has prevented their recognition long ago. Thus, 
by those who have heretofore described these rocks as sedi- 
ments, both secondary cleavage, and the banding due to flow or 
parallel spherulitic layers have been mistaken for stratification ; 
spherulites have been erroneously regarded as concretions; and 
the accompanying pyroclastics, as normal conglomerates or 
slates. 


14 THE JOURNAL OF GEOLOGY. 


It is the purpose of the writer in the present paper to main- 
tain that zz the great crystalline belt of eastern North America, large 
areas of volcanic rocks occur, and that these, in spite of their great 
age, are in all respects the same as modern volcanic materials, save 
for alterations subsequent to their original formation—among which 
alterations devitrification has been one of the most important." 


DISTRIBUTION OF VOLCANIC AREAS ALONG EASTERN NORTH 
AMERICA. 


I shall now proceed to summarize the present state of our 
knowledge of these volcanic areas, as far as they belong to the 
Eastern or Appalachian crystalline belt, omitting all reference 
to the central Canadian, Lake Superior, Missouri, or other more 
western regions of similar nature. In this review I shall com- 
mence with Newfoundland and follow them southwest, parallel 
to the coast. 

Eastern Canada.—In a recent comparison between the Eozoic 
and Paleozoic rocks of eastern America and western Europe, 
Sir William Dawson says that the Huronian was evidently a 
coarse marginal deposit, accompanied by abundant volcanic out- 
breaks, similar to those which occurred about the same time in 
Wales. He is also confident that many of the bedded Huronian 
rocks are really of volcanic origin, being ashes in an altered state.’ 
In the same paper he mentions volcanic rocks, both lavas and pyro- 
clastics, as abundant in the Ordivician and Silurian formations 
of eastern Canada. ) 

The reports. of the Canadian and Newfoundland surveys 
abound in references to rocks of a volcanic character in the 
early Paleozoic and pre-Paleozoic horizons. These references 
are, however, always purely those of a field-geologist engaged 
in a rapid reconnaissance. The frequent use of such field terms 
as felsite, porphyry, trap, amygdaloid, agglomerate, breccia and 
ash suggest a vast development of contemporaneous volcanic 


™On the nomenclature of these ancient and devitrified lavas, see Miss FLORENCE 
Bascom’s paper, this Journal, Vol. I., No. 8, p. 825, Nov._Dec. 1893. 


2 Quart. Jour. Geol. Soc., Vol. 44, p. 801, 1888. 


ee 


THE DISTRIB ULION OF ANCIENT VOLCANTC ROCKS. “15 


materials, but thus far no petrographer has attempted to study 
systematically either the field or microscopical relations of any 
area of these interesting rocks. A very broad and interesting 
field is thus seen to be awaiting investigation in Newfoundland, 
Gaspé, New Brunswick, Nova Scotia and the Eastern Town- 
ships. 

Professor J. B. Jukes, in his ‘‘Geology of Newfoundland,” 
describes old lava flows and accompanying pyroclastic deposits 
as very abundant, especially on the peninsula of Avalon, which 
forms the eastern part of the island.* His observations are con- 
firmed by the later reports of Murray and Howley, who agree 
that the western part of this peninsula was the scene of extraor- 
dinary volcanic activity in very early times.’ 

In his three reports on the eastern portion of Cape Breton, 
Fletcher describes the Ste. Anne, Boisdale, Coxheath, East Bay 
and Mira Hills, as composed largely of ancient (pre-Cambrian ) 
volcanic rocks, among which felsites of all colors, felsite-por- 
phyries, felsite breccias and amygdaloids abound. Similar 
rocks appear also to extend up into, and to form an important 
part of the Cambrian, Silurian and Devonian formations. Ina 
later report on the northern part of Cape Breton, Fletcher ¢ finds 
that the greater part of the northern peninsula is also composed 
of ‘‘felsites,”’ but the petrographical distinctions of both Fletcher 
and Gilpin’ are so indefinite that a variety of coarsely crystal- 
line rocks seem to be embraced in this general designation. In 
describing the Mira “‘ felsites, 


”) 


Fletcher mentions those of Blue 
Mountain and Gull Cape, near Louisburg, as being ‘ globular,” 
or ‘“concretionary,” (coarsely spherulitic?) often presenting 
‘single or united spheroids, the concentric layers of which may 
t Excursions in and about Newfoundland in 1839 and 1840, 2 vols., 1843. Geol- 
ogy, Vol. 2, pp. 245-341. 
? Reports of the Geological Survey of Newfoundland for 1868-1881. 


? Reports of the Geol. Survey of Canada, 1875-76, pp. 369-418; ib., 1876-77, 
PP. 402-456; ib. 1877-78, pp. 1-32, F. 

4Ib., 1882-83-84, pp. 1-98 H. 

5 Quart. Jour. Geol. Soc., Vol. 42, p- 515, 1886. 


16 LTE JOURNAL OP (GEOLOGY: 


be removed like the coats of an onion.”’ He also speaks of 
them as ‘coarsely brecciated” and “vesicular.” A point of 
some interest is Fletcher’s conclusion that ‘both felsite and 
syenitic strata are intimately associated as part of the same 
group of crystalline rocks, differing, not so much in composi- 
tion as in the degree of crystallization they have been subjected 
to” (stc).*. In greatly eroded regions we should expect to find 
surface volcanic rocks associated with their coarser abyssal 
equivalents. 

In Nova Scotia proper the best known area of ancient vol- 
canic rocks is in the northeastern corner of the province, near 
Arisaig, in Antigonish county. These were considered by Sir 
William Dawson in 1850 as ‘‘metamorphic.”* In 1864, Dr. 
Honeyman described them as vesicular traps, amygdaloids and 
porphyries, associated with tufa and tufaceous conglomerate.3 
In his first report on eastern Nova Scotia, Fletcher describes 
variegated, vesicular and amygdaloidal ‘‘felsites” and ‘‘frag- 
mentary felsites,” like those of Coxheath and Louisburg, asso- 
ciated with “syenite” (hornblende granite) and diorite.4 These 
rocks are regarded as pre-Cambrian, and are particularly devel- 
oped at Arichat, Cape Porcupine on the Straits of Canso, and in 
the Sporting, North and Craignish mountains. In the North 
Mountains the felsites are said to pass gradually into syenite 
(Il. c. p. 14). The gradual blending of the felsite and overlying 
George River limestone is attributed to ‘‘common metamorph- 
ism,” rather than ‘to contemporaneous volcanic origin or sub- 
sequent intrusion” (1. c. p. 17). Nevertheless, at Cape Porcu- 
pine the felsite is regarded as possibly an igneous rock, since 
“the apparent lines of bedding are like those of a furnace slag”’ 
(1. c. p. 25). In the subsequent report of the extension. of his 
explorations southward and westward in Nova Scotia, Fletcher 
admits the volcanic origin of the felsitic rocks of Arisaig, Doc- 


tQuoted by GILPIN: Quart. Jour. Geol. Soc., Vol. 42, p. 510. 
2 Quart. Jour. Geol. Soc., Vol. 6, p. 347, 1850. 

3Ib., Vol. 20, p. 333, 1864. 

4 Report of the Geol. Survey of Canada, 1879-80, F. 


TLE DISTRO LMON Om ANCIENT VOBEANIC ROCKS.) V7 


tor’s Brook, Georgeville, Blue Mountain and East River of St. 
Mary’s. These are quite like the Cape Breton and Cape Porcu- 
pine rocks,and carry copper, as they do in South Mountain, Pa., 
and on Lake Superior. He gives the age of these eruptions as 
probably pre-Cambrian, although at Arisaig they may be of any 
age older than Medina. Similar volcanic eruptions occur in all 
strata up to the base of the Carboniferous.* In his last report 
covering Pictou and Colchester counties, the same author 
describes Cambro-Silurian porphyries, agglomerates, fragmental 
felsites, breccias and amygdaloids from Moose and Sutherland 
rivers. A dyke-like mass of volcanic breccia occurs on Sam 
Cameron’s brook. Similar volcanic products are also very 
apparent in the Devonian of these two counties, among the most 
interesting of which are the syenitic granites overlaid by thick 
volcanic deposits at the east end of the Cobequid Hills, as 
described by Dawson.?. The well-known traps of northwestern 
Nova Scotia, along the Bay of Fundy, which furnish the beauti- 
ful zeolites and other minerals, are of Triassic age. 

In New Brunswick and the Gaspé Peninsula, old volcanic 
rocks, like those of Newfoundland and Nova Scotia, are exten- 
sively developed. Ells and Low mention amygdaloidal traps and 
porphyries cutting various strata of Gaspé, up to and including 
the Devonian. Felsitic rocks, similar to those which are better 
known further to the south, are rather vaguely mentioned by 
Robb in northern New Brunswick.* Ells, in his report on the 
same region in 1879-80, clearly describes as volcanic both acid 
and basic rocks. A vast area of felsite, petrosilex, porphyry 
and breccia, like that near St. Johns, is developed in the upper 
Nipisiguet river and lake Nictor. Another like it extends 
from the upper Upsalquitch river along Jacket river to the 
bay of Chaleur, while great masses of basic volcanics (amyg- 


tIb., 1886, P. 


2 Acadian Geology, 1878, suppl., p. 79. 
Report of the Geol. Survey of Canada, new ser., Vol. 5, 1890-91, P. pp. 147-166. 


3Ib., 1882-83-84, E. and F. 
4Ib., 1870-71, p. 245. 


18 ITGUE, JO ULINAUE, (UP (GIBIOIL ONG I 


daloids, aphanites, etc.) occur around the head of the Bay of 
Chaleur and Dalhousie, as well as on the upper Upsalquitch and 
Elm Tree rivers. Many of these rocks are pre-Cambrian, while 
others cut the Silurian strata.‘ Great sheets of contemporane- 
ous trap are also found by Ells in the Silurian, and to a very 
small extent in the Devonian, along the north shore of the Bay 
of Chaleur. Bailey explored parts of northern and western New 
Brunswick, especially in Carolton, York and Victoria counties, 
and found porphyries, felsites and amygdaloids, intrusive in the 
Silurian and older formations in Canterbury, Woodstock and 
Kent townships, near the St. Johns river.? Still later Bailey 
and McInnes continued similar explorations, and found signs of 
intense volcanic action in the Niagara limestone at Pointe aux 
Trembles, and a great development of acid and basic surface 
rocks near the Aroostook river and at Presqu’ile and Haystack 
mountain in Maine.3 The same is true near Tobique lake, 
farther to the northeast. 

As early as 1839, Gesner describes the volcanic rocks along 
the Bay of Fundy, in southern New Brunswick, as belonging 
to several distinct horizons.t In 1865, Bailey, Matthew and 
Hartt distinguished two groups mainly of volcanic origin, to one 
of which, the ‘‘Coldbrook,” they assigned a Huronian, and to 
the ‘other, the “Bloomsbury, ja) Devonian ages) ings 72, 
Bailey and Matthew, after a season’s field-work with Dr. T. 
Sterry Hunt, united the Coldbrook and Bloomsbury groups on 
purely lithological grounds, and for the same reason joined with 
them two other volcanic series—the Coastal and Kingston 
groups—exposed at other localities in southern New Bruns- 
wick.© The petrographical characters of these rocks were those 
regarded by Hunt as sufficient demonstration of Huronian age. 
The acceptance of this fallacious principle exercised a distinctly 


tTb., 1879-80, pp. 35 to 42. 

2Tb., 2882-83-84, G. pp. 15 and 20; ib., 1885, G. pp. 22 and 28. 

31b., 1886, N. pp. 14-15; and ib., 1887-88, M. pp. 32 and 47. 

4First Report on the Geological Survey of the Province of New Brunswick, by 
ABRAHAM GESNER. 87 pp. 18309. 

5 Observations on the Geology of Southern New Brunswick. 1865. 


© Report of the Geol. Survey of Canada, 1870-71, pp. 57-133. 


LTO See CMO NRO NAN CHL NT VOECANIG ROCKS) iO 


retarding effect on the deciphering of New Brunswick geology. 
Numerous occurrences of felsite, porphyries and amygdaloids 
were described between Musquosh Harbor and Loch Lomond, 
near the city of St. Johns, and along the line between Kings 
and Queens counties (Coldbrook and Bloomsbury groups). 
Similar rocks were traced from L’Etang Harbor, near Passama- 
quoddy Bay, along the edge of the Bay of Fundy to Shepody, 
in Albert County (Coastal group); and finally, a belt of ana- 
logous composition was described between the Long Reach of 
the St. Johns river and Mace’s bay (Kingston group). These 
rocks were at this time, however, on account of Hunt’s influ- 
ence, united with their associated sediments, and nothing is said 
about their volcanic character. These authors were forced to 
regard similar rocks on the shores of Passamaquoddy bay as 
Silurian, because of associated fossils, in spite of their litholog- 
ical identity with the ‘“Huronian.’”’ These they called the Mas- 
carene series.” 

Four years later the same authors united the Kingston and 
Mascarene groups and regarded both as upper Silurian.? In a 
report of the pre-Silurian rocks of Albert, eastern Kings, and 
St. Johns counties, Ells gives some clear statements relative to 
the volcanic rocks of southern New Brunswick. He says: 

“In their lithological aspect, the rocks forming the southern metamorphic 
belt present great diversity. Their general character is of two kinds—altered 
sedimentary and volcanic. * * * In the latter we include the great mass 
of petrosiliceous rocks, so called, with breccias and other ash rocks, which 
in places show bedding, but this is often so obscurely marked as to be exceed- 
ingly doubtful. * * * Near the contact of the volcanic and sedimentary 
rocks we find an extraordinary development of generally coarsely crystalline 
diorites and syenites, which would seem to form the basal portion of the vol- 
canic part of the series.’3 

A report on the same rocks was published at the same time 
by Bailey, who divides them into a feldspathic, syenetic and 
gneissic group, including limestones, serpentines, and dolomites 

TIb., pp. 144-158. 


2 Ib., 1874-75, pp. 85-89. 
3Ib., 1877—78, D. p. 3. 


20 THES JOURNALEVOF GEOLOGY. 


(Laurentian); a felsite-petrosilex group (Lower Huronian or 
Coldbrook); and a schistose, chloritic micaceous group (Upper 
Huronian or Coastal).* The results of all their work on the 
rocks of southern New Brunswick is summarized by Bailey, 
Matthew and Ells, with a general geological map in three 
sheets.? 

That portion of the Province of Quebec lying south and 
east of the St. Lawrence is called the Eastern Townships. We 
have already considered that portion of it composing the Gaspé 
peninsula. The portion lying west of Maine and north of New 
Hampshire and Vermont was supposed by Logan to be wholly 
occupied by rocks of the Quebec Group. In 1879, Dr. Selwyn 
divided the rocks of this zone into three groups, which he 
defined as lower Silurian; volcanic (probably lower Cambrian); 
and crystalline (probably Huronian). The lower of these divis- 
ions forms an anticlinal axis extending from Lake Memphrema- 
gog to L’Islet County, 150 miles. It contains a great variety 
of altered sedimentary beds, associated with ‘‘diorites, doler- 
ites, serpentines, amygdaloids, and volcanic agglomerates,” 
regarded by Hunt as altered sedimentaries. The second divis- 
ion, said to be intimately related to the last, is largely composed 
“especially on the southeastern side of the axis, of altered volcanic products 
both intrusive and interstratified, the latter being clearly of contemporaneous 
origin with the associated sandstones and slates.” 

These rocks are designated as 
‘‘dioritic, epidotic, and serpentinous breccias and agglomerates; diorites, 
dolerites and amygdaloids holding copper ore; serpentines, felsites and 
some fine grained granitic and gneissic rocks.” 

They are especially developed along the contact of the last- 
mentioned group, of which they ‘“‘may be merely the upward 
extensions, > plinvavlater spaper om the @uebec Group, Di sel- 
wyn considers these volcanic rocks thoroughly from the English 
point of view. He says: 


* Il}, IDID), jo 2 
Moy, 1KeI7ies—7/O), ID); jos AO 
3Jb., 1877-78, A. pp. 5-9. 


LAE DUES TRIO MLON SOL ANCIENE: VOLCANIC ROCKS. 21 


“T would alse submit that neither a schistose nor a bedded structure can be 
accepted as proof of a non-igneous or volcanic origin, and that a once mas- 
sive lava-flow, whether augitic or feldspathic, is as likely, through pressure 
and metamorphism, to assume a schistose structure as are ordinary sedi- 
mentary strata. It is, | am aware, not in accordance with generally received 
ideas on the nature of ancient igneous rocks to suppose they can be schistose 
and stratified, especially so in America, where volcanic agency in the earlier 
geological periods has been almost entirely ignored, and all those rocks 
which by their microscopic characters and chemical composition, and by 
their geological associations and relations, point to volcanic agency as the 
cause of their formation, have been said to be ‘ot ceneous, but metamorphic 
im origin, a description which, it seems to me, is decidedly self-contradic- 
tony.i2 
Selwyn later again maintained his volcanic group, and pub- 
lished microscopic descriptions of some of its rocks (quartz- 
porphyry and porphyrite) by Adams.’ Little or nothing is added 
to our knowledge of the strictly volcanic rocks by the two sub- 
sequent reports on the geology of the Eastern Townships by 


Ells.3 


The recognition of ancient volcanic rocks in the United 
States is far behind that which prevails in Canada. This, as 
has already been pointed out, is due to the influence of so-called 


I 


‘‘metamorphic” ideas, or more properly to the Wernerian doc- 
trine, that every rock showing any foliated or parallel structure 
is sedimentary. 

New England.—Very little definite information can be gath- 
ered from the earlier reports on the geology of Maine, by Jack- 
son and C. H. Hitchcock, regarding the old volcanic deposits. 
Jackson frequently uses such petrographical terms as ‘‘amygda- 
loidal trap, ribbon jasper, clinkstone porphyry, and breccia com- 
posed of an infinity of fragments of jasper,” in describing the 
rocks near Eastport and Machiasport, on the Maine coast. He 
regarded the basic rocks (trap) as eruptive, but the “jasper” as 
semifused sediments whose lines of stratification were still pre- 

t Trans. Roy. Soc. Canada, Vol. 1, p. 10, 1882. 

2 Report of the Geol. Survey of Canada, 1880-82, A. p. 2 and pp. 10-14. 

3Ib., 1886, J., and ib., 1887-88, K. 


No 
i) 


THE JOURNAL OF GEOLOGY. 


served.t His descriptions are, however, very suggestive, espe- 
cially in light of the truly volcanic rocks which have been 
recently discovered in the older strata of Maine. . C. H. Hitch- 
cock, in his Maine reports, regards the acid volcanic rocks near 
Machiasport as altered slates, and mentions extensive areas of 
similar rocks on Moosehead, Portage, Long, and Chamberlain 
lakes, as well as along the Aroostook and Penobscot rivers, in the 
interior of the state.* Goodale gives four patches of analogous 
‘siliceous slates” in York county, and five in Oxford county, 
and J. H. Huntington describes the summit of the diorite south- 
east of Kennebago lake, in western Maine, as composed of com- 
pact felsite, which he regards as an eruptive rock. The first 
definite descriptions of ancient volcanic rocks in Maine was 
given by Professor Shaler, who examined the regions about 
Eastport and Mount Desert. Near Eastport, and especially on 
McMaster’s island, three types of volcanic material are largely 
developed: 1) detrital accumulations which have fallen through 
the air; 2) true lava flows; 3) dykes. They seem to belong to 
various horizons of Silurian age. A similar series of interstrati- 
fied volcanic breccias, lava flows and ash beds are described as 
forming a large part of Mt. Desert island south of Southwest 
Harbor, and the Cranberry Isles.5 

The writer has had the opportunity to personally examine 
the volcanic rocks of the Mt. Desert region, and he is indebted 
to Professor W. S. Bayley of Waterville, Me., for specimens and 
slides of the beautiful lavas of Vinal Haven, and to Mr. E. B. 
Mathews for notes and specimens of similar rocks from Mt. 
Kineo on Moosehead Lake. 

Along the shores of Cranberry Island occur hard jaspery 
felsites, often porphyritic, and exhibiting such characteristic 
features of glassy rocks as spherulites, single and in bands, flow- 


First Report on the Geology of the State of Maine, 1837, p. 12 and pp. 36-42. 
2 Geological Report, 1861, p. 190, and p. 432; also ib., 1863. p. 330. 

3Proc. Am. Assn. Adv. Sci., Vol. 26, p. 286, 1877. 

4Am. Jour. of Science (3d ser.), Vol. 32, pp. 40-43, 1886. 

5 Eighth Ann. Report U. S. Geol. Survey, pp. 1037, 1043, 1054. 1889. 


THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 23 


structure, etc., in great perfection, although all trace of the 
original glass has long since disappeared. The rocks collected 
by Professor Bayley on the north side of Vinal Haven and on 
the opposite shore west of North Haven are, according to his 
field observations, all surface flows or tuffs. Of the nine speci- 
mens kindly submitted to me for examination by Professor 
Bayley, one is a medium grained microgranite and all the others 


Gok 


Fic. 1. Devitrified glass-breccia from north side of Vinal Haven, Penobscot Bay, 
Me. Magnified six times. 


are devitrified glassy rocks, which were once either obsidians, 
glass breccias, or tuffs. No. 94 is a banded flow-felsite, a devit- 
rified glass with narrow chains of spherulites. No. 100 is a 
devitrified obsidian containing delicate flow-lines produced by | 
trichites, some zircon crystals, and spherulitic bands in which 
epidote has been secondarily produced. No. 126 isa pale gray 
felsite containing large round nodules which may be spherulites. 
Under the microscope it shows a pronounced perlitic structure. 
These rocks contain spherulitic structures which are not devitri- 
fication products but original, if we may judge from their abso- 
lute identity with similar structures in the glassy rocks from 
Obsidian Cliff. The other five specimens are fine grained vol- 


24 LH JOURNAL OF “GHOLOGY. 


canic ashes, most of them composed of very sharply angular 
fragments of devitrified glass or pumice with beautiful flow 
structures. The delicate detail produced by trichites in one of 
these is rather roughly represented in Fig. 1. It is not unlike 
the devitrified glass-breccia described by the writer from Onap- 
ing river in the Sudbury district." 

The specimens collected by Mr. Mathews at Mount Kineo 
on Moosehead Lake, and kindly loaned me for examination, are 
typical quartz-porphyries or keratophyres, some of which exhibit 
such perfect and delicate flow-lines that they can be regarded 
only as devitrified glassy lavas. 

In New Hampshire felsites and quartz-porphyries abound. 
They were regarded as eruptive by Hitchcock and by Hawes 
when they occur in dykes, although the latter regarded many of 
them, especially when interstratified, as sediments fused 27 satz.? 
There are as yet no published descriptions which make it reason- 
ably certain that truly volcanic, as contrasted with abyssal 
igneous rocks, occur within this state. 

The important development of ancient volcanic rocks _in 
eastern Massachusetts, in the neighborhood of Boston, has been 
more discussed than any other similar region on this continent. 
An excellent résumé of the development of opinion regarding 
these rocks has been given by Whitney and Wadsworth.  E. 
Hitchcock held correct views as to the igneous character of all 
the massive rocks, although he regarded the amygdaloids and 
some of the apparently stratified felsites as altered sediments. 
Later the influence of Hunt created a general impression that the 
greater part of these rocks—even the granites—were of sedi- 
mentary origin. Wadsworth was the first to successfully combat 
this idea, and to show that not only were the coarsest massive 
rocks igneous masses, but even the finer jaspery felsites and their 

t Bull. Geol. Soc. Am., Vol. 2, p. 138, 1891. 

Report of the Geol. Survey of Canada, 1890-91, F. p.75. 

2 See Geology of New Hampshire, Vol. 2, p. 260, and Vol. 3, part 1V., Mineralogy 
and Lithology, p. 171, 1878. 

3 The Azoic System, pp. 398—-44c, 1884. 


SEEDED, JOS UTRIGE (OTGAOIN (OWE, ALIN CHIPIN TE WAGYEOAIN IEG Te QXONKGS 57415) 


accompanying fragmental materials were the products of ancient 
volcanic action. He maintained that the felsites of Marble 
Head were merely altered rhyolites which had once been quite 
like those of the western Cordilleras ; and their banding was flow- 
structure ; and that they were accompanied by ash beds which 
he called porodites.1 Two years later the detailed work of Diller 
and Benton established the volcanic character of the felsites of 
Medford, Melrose, Malden, Sangus, Wakefield and Lynn, and of 
the amygdaloid of Brighton.’ 

Other areas of similar rocks occur near Newburyport, and 
also to the south of Boston at Needham, Dedham, Milton, Blue 
Hill, Hingham, Nantasket and Manomet,3 but these have not as 
yet been so carefully examined as those farther north, although 
Crosby, in his recent ‘‘ Geology of Hingham,” classes the mela- 
phyre. porphyrite, and felsite of Nantasket and Hingham as 
effusive or volcanic rocks, and describes the latter as ‘‘undoubt- 
edly an ancient, devitrified obsidian.” 4 

The Middle Atlantic States—In New York state there are, 
as far as the writer is aware, no remains of igneous rock which 
have solidified at the surface. Nevertheless, the isolated and 


The Classification of Rocks. Bull. Mus. Comp. Zool., Harvard Coll., Vol. 5, p. 
282, 1879. It is worthy of note, in view of all the erroneous ideas that have prevailed 
regarding the Boston felsites, that as early as 1822, Dr. Thomas Cooper, President of 
the College of South Carolina, in an article on ‘“ Volcanoes and Volcanic Substances” 
says: “ No person accustomed to volcanic specimens can look at the porphyries from 
the neighborhood of Boston, in my possession, and doubt of their volcanic origin.” 
(Am. Jour. of Science, Ist ser., Vol. 4, p. 239). 


2“ The Felsites and Their Associated Rocks North of Boston,” by J. S. DILLER, 
Bull. Mus. Comp. Zool., Vol. VIL., p. 165, 1881; and “‘ The Amygdaloidal Melaphyre of 
Brighton, Mass.,” by E. R. BENTON, Ph.D., Proc. Bost. Soc. Nat. Hist., Vol. 20, pp. 
416-426, 1880. The writer is indebted to Mr. Diller for the privilege of examining 
his collection of slides of the Boston rocks which are in all essential respects identical 
with those from the coast of Maine, from South Mountain and North Carolina. 


3 E. Hircucock: Final Report on the Geology of Massachusetts, Vol. 1, p. 150, 
1841; W. O. Crossy : Geology of Eastern Massachusetts, pp. 79-95, 1880. 


4 Proc. Bost. Soc. Nat. Hist., Vol. 25, p. 502, 1892. See also by the same author : 
The Lowell Free Lectures on the Physical History of the Boston Basin, 1889; andthe 
Geology of the Boston Basin, Vol. 1, Part 1. Occasional Papers of the Boston Soc. 
Nat. Hist., IV., 1893. 


26 THE JOURNAL OF GEOLOGY. 


highly differentiated ‘‘ Cortlandt Series,” near Peekskill, presents 
us with the deeply eroded roots of an ancient volcano, probably 
of Cambrian or Silurian age, whose superficial parts have entirely 
disappeared.” The eleolite-syenite area in northern New Jersey 
is probably of the same character. 

In Pennsylvania and Maryland we find in the South Moun- 
tain or Blue Ridge, between Harrisburg and the Potomac, one 
of the most highly diversified and perfectly preserved areas of 
pre-Cambrian volcanic rocks in the world. Its position is estab- 
lished as below the Olenellus sandstone; it presents both acid 
(rhyolitic) and basic (basaltic) types; it exhibits within limited 
shear-zones the plainest effects of dynamic action, but its great 
mass is nevertheless so little changed that each microscopic 
structure of glassy rocks is clearly recognizable. Skeleton 
crystals, minute pores and larger vesicles, protoclastic breaking 
of the phenocrysts, fluidal structures of every kind, trichites, 
spherulites, axiolites, lithophysal and perlitic parting have lost 
none of their original sharpness, in spite of the complete devitri- 
fication of the glassy base. Most of the rocks were probably 
always wholly or mostly crystalline, but some regions, like the 
Bigham Copper and Raccoon Creek, display the old spherulitic 
obsidians and pumice ina manner allowing of no doubt. The 
pyroclastic materials accompanying these old lavas are also finely 
developed—ash-beds, coarse and fine flow- and tuff-breccias, etc. 
The precise centers of eruption within this region have not yet been 
definitely located, but with what has already been published 
regarding these rocks and the further details which may be soon 
expected, no further description of them is here necessary.? The 
entire misunderstanding of these rocks by Rogers, Hunt, Lesley 
and Fraser, who interpreted them as altered slates and their sec- 
ondary cleavage as bedding, has greatly retarded the solution 

* PROFESSOR DANA once suggested that the Cortlandt massive rocks might have 
been formed by the metamorphism of “volcanic debris or cinders” (Am. Jour. of 
Science, 3d ser., Vol. 22, p. 112, Aug. 1881), but he subsequently admitted their intru- 


sive character (ib. Vol. 28, p. 384, Nov. 1884). See also opinions of the present writer 
(ib. Vol. 36, p. 268, Oct. 1888). 


2Am. Jour. of Science (3rd ser.) Vol. 44, December, 1892, and Vol. 46, July, 1893. 


THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 27 


of the geology of South Mountain, and has for many years 
invested it with a reputation for complexity which it in no way 
deserves.” 

In Maryland and Virginia the acid and basic lavas and tuffs 
of South Mountain are extended southward as an important ele- 
ment in the composition of the Blue Ridge. They have been 
somewhat studied by the writer in this region and have been 
mapped and described by Keith.? This author mentions two 
quartz-porphyry areas showing flow-structure and tuffs, the 
larger between Catoctin and Blue mountains in Maryland, and 
the smaller near Front Royal in Virginia. He says that the 
diabase shows many indications of being a surface flow, and that 
it extends along the Blue Ridge from Maryland half way across 
Virginia, with an average width of twenty miles. 

Southern States—Volcanic rocks are largely developed in the 
central portion of both the Carolinas, as may be gathered from 
the old reports of Emmons and Lieber. During the past sum- 
mer the writer had the opportunity of examining the belt in 
Chatham and Orange counties, North Carolina, in company with 
the State Geologist, Professor J. A. Holmes. The time at com- 
mand was inadequate for the thorough exploration of the vol- 
canic belt which skirts the western edge of the Triassic sandstone, 
but in a drive from Sanford to Chapel Hill an abundance of the 
most typical ancient lavas, mostly of the acid type, was encoun- 
tered. On the road from Sanford to Pittsboro purple felsites 
and porphyries showing spherulites and beautiful flow-structures, 
and accompanied by pyroclastic breccias and tuffs, were met with 
two miles north of Deep river and were almost continuously 
exposed to Rocky river. Here devitrified acid glasses with 
chains of spherulites and eutaxitic structure were collected, while 
beyond as far as Bynum on Haw river, four miles northeast of 


: ™See J. P. LestEY: Summary Final Report, Penn. Geol. Survey, Vol. I, p. 151, 
1892. 

2 American Geologist, Vol. 10, pp. 366-68, December, 1892. Geologic Atlas of 
the U. S., Harper’s Ferry Sheet (2 press). For their distribution in Maryland see the 
Geological Map of the State, edited by G. H. WiLLiAms, and published in the 
World’s Fair Book “ Maryland,” Baltimore, 1893. 


28 WINS OW AINAUL, (OF CIS OILONG 


Pittsboro, the only rocks seen were of the same general charac- 
ter. On the farm of Spence Taylor, Esq., in Pittsboro, a bright 
red porphyry with flow lines is exposed in so altered a condition 
that it can be easily cut into any form with a knife, though it 
still preserves all the details of its structure. It looks not unlike 
the well known pipe-stone, or Catlinite of Minnesota. Three 
quarters of a mile beyond Pittsboro on the Bynum road there is 
a considerable exposure of a basic amygdaloid. South of Hack- 
ney’s Cross Roads there are other excellent exposures of the 
ancient rhyolites with finely developed spherulitic and flow- 
structures. Numerous specimens were here collected which 
place the character of these rocks as surface flows beyond a 
doubt. Another locality in the volcanic belt was visited on 
Morgan’s Run, about two miles south of Chapel Hill. Here are 
to be seen admirable exposures of volcanic flows and breccias 
with finer tuff deposits, which have been extensively sheared into 
slates by dynamic agency. Toward the east and north these 
rocks pass under the transgression of Newark sandstone. The 
accompanying sketch-map (Fig. 2) shows the relations of the 
above mentioned localities in Chatham and Orange counties, 
NC.” Krom still another locality vat the cross-road mearuthe 
northern boundary of Chatham county, fifteen miles southwest 
of Chapel Hill, Professor Holmes informs me specimens of 
undoubted volcanic rocks have recently been secured; he has 
also sent to me within the past month a suite of similar 
specimens from Pace’s Bridge on Haw river, three miles above 
Bynum. 

In his upper division of the Taconic System in North Caro- 
lina, Emmons describes numerous beds of “‘ chert or hornstone”’ 
intercalated in the slates and sometimes forming isolated bosses, 
whose origin he is at a loss to account for. He says they are 
not metamorphic, but does not suggest for them an igneous ori- 
gin.t The hypothesis that these rocks may also be of volcanic 
origin is sustained by Emmons’ description of ‘‘brecciated con- 


glomerates’ 
™ Geological Report of the Midland Counties, N. C., 1856, pp. 66-68. 


associated with the chert beds, which are composed 


THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. ‘29 


of an argillaceous or chloritic base, containing angular chert frag- 
ments of all sizes up totwo feet. He mentions many localities 


fo) 5 


Scale of Miles. 


G22) : 
Fic. 2. Sketch map of parts of Chatham and Orange counties, N. C., showing locali- 
ties for ancient volcanic rocks. 
for these rocks, most of which are near the Yadkin river in 
Davidson, Rowan and Montgomery counties. 
Iam informed by Mr. Arthur Keith that he discovered a 


30 LTE JOURNAL OFNGEROLOGN4 


large area of quartz-porphyry in the Great Smoky Mountains in 
Yancey Co., N. C., during the past summer. 

The geological reports on South Carolina, by Lieber, describe 
a great development of igneous rocks which cross the state in 
the continuation of the North Carolina volcanic belt and which 
are themselves very probably in part of surface origin. His first 
report for 1856, which treats of Chesterfield, Lancaster, Chester 
and York counties, mentions among other more coarsely gran- 
ular igneous rocks, eurite or quartz-porphyry, aphanitic-porphyry 
and melaphyre.*. The counties of Union and Spartanburg, dealt 
with in Lieber’s second report, are much poorer in igneous rocks, 
though he here adds the types schistose aphanite and minette. 
On the geological map of South Carolina, published by the 
Department of Agriculture in 1883, the belt of aphanitic green- 
stones and porphyries is shown to be continuous across the state 
in a southwest direction, and the statement is made that the 
ereenstones predominate toward the north, and the porphyries 
toward the south, in Abbeville county. 

Upon an expedition undertaken at the instigation of the 
writer, Prof. S. L. Powell of Newbury, S. C., found at Chester 
abundant eruptive rocks (granites and diorites), but none of 
unmistakably volcanic origin. At Lancaster, on the other hand, 
he found amygdaloids and felsites, showing distinct flow-struct- 
ures which are certainly of igneous origin and could only have 
solidified at the surface. 

In Georgia and Alabama nothing can be stated with cer- 
tainty in regard to ancient volcanic rocks as the crystalline 
portions of these states have not as yet been petrographically 


investigated. The porphyry area of Abbeville county, S. C., is 


probably continued into Georgia. One single specimen of quartz- 
porphyry showing a beautiful micropoikilitic structure, collected 
in northwestern Georgia near the Tennessee liné, has already 
been mentioned by the writer.* A box of specimens kindly sent 

t Report on the Survey of South Carolina for 1856, 2d ede Columbia, 1858, Pasi 
Lieber had the German ideas regarding igneous rocks and their nomenclature. His 


“trachyte,” ‘“domite”? and “phonolite” are probably fine grained varieties of the 
acid volcanic types. 


—_ 


LHE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 31 


to me for examination by Professor Eugene Smith of Alabama, 
proved to contain nothing which could be identified as ancient 


volcanic material. 
GENERAL CONCLUSIONS. 


The above rapid survey of the now known and probable areas 
of ancient volcanic rocks in the crystalline portion of the Appa- 
lachian system reveals the fact that this class of material is 
both abundant and widely distributed. From Newfoundland to 
Georgia it has been identified. For many areas the evidence of 
surface or volcanic origin is conclusive, while in many others it 
is as yet only probable. 

The areas of these ancient volcanic rocks now known fall 
roughly in two parallel belts (see map); of these the eastern 
embraces the exposures of Newfoundland, Cape Breton, Nova 
Scotia, the Bay of Fundy, Coast of Maine, Boston basin and the 
central Carolinas; while the western belt crosses the Eastern 
Townships and follows the Blue Ridge through southern Penn- 
sylvania, Maryland, Virginia, North Carolina to Georgia. 

The purpose of the present communication will be accom- 
plished if it succeeds in directing attention to this group of 
rocks. New areas should be added ; probable areas investigated ; 
and known areas monographed all along this old mountain range. 
How fruitful a field is here spread out to students of geology 
and petrography may be seen from the results of work in anal- 
ogous regions by Harker? and Migge.3 

The identification of truly volcanic rocks in highly or partly 
crystalline terrains possesses far more than a petrographical sig- 
nificance, since by fixing what was the surface at the time of 
their formation, they furnish a certain datum for tracing out the 
sequence of later geographic changes and geological develop- 
ment. GEORGE HUNTINGTON WILLIAMS. 


* Am. Jour. of Science (3d ser.) Vol. 46, p. 47, July, 1893; and this Journal, Vol. 1, 
| Pp. 179, 1893. 
_ * The Bala Volcanic Series of Caernarvonshire, Sedgwick prize essay for 1888, by 
A. HARKER, Cambridge, 1889. 
3 Untersuchungen iiber die “ Lenneporphyre”’ in Westfalen und den angrenzenden 
Gebieten by O. Mtccr. Neues Jahrbuch fiir Min., etc., Beilage Band viii., pp. 525— 
721, 1893. 


REVOLULION IN LH TOROGRAREY Ob MEE PACING 
COAST SINGER Eth FAURE NOUS 
GRAVE re KO 


INTRODUCTION. 


Ir is now generally recognized that rivers are the architects 
and sculptors of their own valleys. The land is everywhere 
shaped largely by its streams, and the forms developed are serial, 
beginning with the river’s youth and changing in the progress of 
time until finally the stream attains old age, and its topographic 
‘work is completed. In their early life, when rivers have their 
highest grade, they wash away their beds more than their banks, 
and cut cafions. Their beds are a succession of gentle flows, 
rapids, and falls, over the softer and harder beds. When by 
deep cutting the fall of the stream is reduced, it tends to spread 
out and erode its banks, the cafons widen, and the divides 
become narrow and sharp, with rugged peaks showing the 
stream’s maturity, but the work of the fluvial sculptor still con- 
tinues, and the mountains are reduced to hills and the hills to 
knolls so low that the general aspect of the country is that of a 
plain. The streams are powerless to erode the land below the 
level of this gentle plain, which has been appropriately named 
by Powell the Baselevel of Erosion. Thus in a complete cycle 
of a river’s history the canon and the broad divide, or plateau, 
are features of its youth; narrow, sharp, more or less rugged 
divides of its maturity, and the baselevel of its old age. The 
cafions have then disappeared, and the land reduced by long 
continued erosion approximately to sea level. 

The development of the baselevel begins upon the seashore 

tPublished with the permission of the Director of the United States Geological 
Survey. Abstract from a paper upon the same subject which will appear in the 14th 
Annual Report of the United States Geological Survey. Read before the Geological 
Society of Washington, April, 1893. 

32 


ROTA GUANA OLN LETRA CLG COAST 33 


by which the level is determined, and gradually spreads inland 
toward the principal divides. Under similar conditions the 
shales and limestones wear away more rapidly than the coarser 
sediments and crystalline rocks, and local baselevels appear for 
a time determined by the harder rocks. But these are all oblit- 
erated in a general baselevel when it is completely developed. 
The land is so unsteady that it rarely, if ever, remains without 
elevation or depression long enough for the complete develop- 
ment of a baselevel of erosion. It commonly happens, however, 
that the large masses of harder rocks upon the slopes of the 
principal divides form independent elevations in the plain which 
may be more or less distinctly defined upon the softer rocks. 
The topography of the region is then essentially a peneplain. 

It is evident that a general baselevel of erosion must have 
originated approximately at sea level. This is the only position 
in which a very extensive baselevel of erosion can originate. If 
we now find such a baselevel at considerable elevation above the 
‘sea, its position furnishes evidence that since the baselevel was 
formed the country has been uplifted in the process of mountain 
building. 

Upon our Atlantic slope, ancient baselevels of erosion are 
well developed in the Piedmont region and elsewhere at consid- 
erable altitudes above the sea, as shown by Davis, McGee, Wil- 
lis, Hayes, and Campbell. The ancient mountains have been 
swept away, and the modern mountains, at least in large part, 
are the result of later upheavals. Similar changes have taken 
place on the Pacific slope. Russell found in the St. Elias range, 
at an elevation of over 5,000 feet, shells of marine mollusks still 
living along the Pacific coast, showing that the great mountain 
range had been uplifted in very late geologic time. So, also, the 
Sierra Nevada and Coast ranges, and to some extent the Cascade 
range, now such prominent features of the Pacific coast, have 
been upheaved to their present great height, and deep cafions cut 
upon their slopes in the later geologic ages, At an earlier epoch 
the whole country was comparatively low and near sea level, or, 
-in other words, near its baselevel of erosion. The mountain 


34 LSLEN OWT INALE OF AGLI OL O GNA 


ranges were then inconspicuous and the slopes everywhere 
gentle. 

It is the object of this paper to trace out this ancient topog- 
raphy and briefly to outline the great changes by which the pres- 
ent features were developed. Incidentally the auriferous gravels 
will be considered, because they originated in large part at the 
beginning of its topographic revolution, which has on this 
account a most important economic interest. 


TOPOGRAPHY OF THE PACIFIC SLOPE. 


There are two prominent topographic belts on the Pacific 
slope. One is the platform of the interior basin region, and the 
other the mountain belt which lies upon the border of the conti- 
nent. The latter embraces the Sierra Nevada, Cascade, and Coast 
~ ranges, as well as the Klamath Mountains in northwestern Cali- 
fornia and southwestern Oregon, where all the ranges meet. 
Between the ranges to the southward of the Klamath Mountains 
lies the Great valley of California, and to the northward the 
Sound valley extends from central Oregon across the state of 
Washington. The mountains are everywhere deeply cafioned by 
the rivers, but if we take a more general view, overlooking those 
features which are still developing, we shall discover others of 
much greater antiquity. 


ANCIENT BASELEVEL OF EROSION. 


Upon the northwestern and northern border of the Sacramento 
valley —Upon the northwestern border of the Sacramento valley 
is a well-marked plain of erosion, which extends for nearly one 
hundred miles from about the 4oth parallel around the northern 
end of the Sacramento valley to near the Great Bend of Pit 
river. It varies from one to fourteen miles in width, and is best 
marked in the Greasewood and Bald hills of Tehama and Shasta 
counties. The larger portion of the plain has been carved upon 
the upturned edges of the Cretaceous strata, and the denudation 
has reduced the thick, hard conglomerates and sandstones to the 
same level as the soft shales. At a number of places the well- 
defined plain extends for several miles into the area of harder 


ROROCGKAPTINAOD STE PA ChACT COAST: 35 


and more durable metamorphic rocks of the Klamath Mountains. 
Excellent views of this plain may be obtained from the Red 
Bluff and Hayfork stage road, five miles northwest of Hunter’s 
postoffice, and from the mountain roads and trails leading west- 
-ward from Stephenson’s, Miller’s, Lowrey’s, and Paskenta, in 
Tehama county. 

In the Klamath Mountains—The plain already noted lies at 
the southeastern base of the Klamath Mountains, and passes by 
gradual and rapid transition into the steeper slopes of the moun- 
tains in such a way as to indicate that the plain may have once ex- 
tended across the region now occupied by the Klamath Mountains. 
Within that group the plain has been recognized thirty miles 
southeast of Humboldt bay, about Shower’s pass, at an altitude 
of nearly 4,000 feet, and a little farther east, in the even crest of 
South Fork Mountain, at an altitude of 6,000 feet. Major J. W. 
Powell informs me that he has observed a deformed baselevel in 
the Coast Range north of San Francisco. It will doubtless yet 
be found at many points, but on account of the great deforma- 
tion which has taken place in the Klamath Mountains and Coast 
Range since the baselevel was formed, it is difficult to trace. 

On the western slope of the Sierra Nevada.—The baselevel we 
have followed from Elder creek to Pit river was evidently deter- 
mined by a body of water occupying the Sacramento valley, and 
traces of a corresponding level might be expected along the 
opposite shore about the Sierra Nevada. z 

The western slope of that range may be briefly described as 
an inclined plane, interrupted only by the narrow cafions of the 
present streams. Professor J. D. Whitney graphically portrayed 
the region as follows: ‘To one standing on some point, not too 
elevated, but from which a good view of the surface of the coun- 
try along the flanks of the Sierra may be had, its slope will 
appear to be quite uniform and unbroken to one looking along a 
line parallel with the general trend of the range. It will seem, 
provided the point of view be favorably selected, as if the whole 
region was a gently descending plain, sloping down to the Great 
valléy at an angle of not more than two or three degrees. And 


36 TLE POURNAT VOR SGHOLOGN, 


the slope of the Sierra is—in the mining region at least—quite 
moderate, for if we allow a rise of 7,000 feet from the lower edge 
of the foothills to the crest of the range, the distance between 
the two points being about seventy miles, the average rise is only 
100 feet to the mile, which gives an angle of slope of less than 
two degrees. And if one ascends the Sierra, keeping on the 
divide between any two rivers in the mining districts, he will find 
himself, for most of the time at least, on what seems to be a 
plain with a very gentle rise. Let the traveler, however, turn 
and attempt to make his way across the country, in a line par- 
allel with the crest of the range, and he will discover that this 
apparent plain is cut into by the gorges or cafions in which the 
present rivers run, in a most extraordinary manner; he will find 
it several hours’ work to descend into one of these and rise again 
to the general level on the other side, even if assisted by a well- 
beaten trail. All along the western slope of the Sierra the streams 
have worn for themselves deep canons, and it is these tremendous 
gorges which form the leading feature of the topography of the 
region. If the streams ran nearly on a level with the general 
elevation of the surface, the whole character of the mountain 
slope would be changed. This was formerly the condition of 
the drainage of the Sierra slope.”* Concerning the topography 
of the same region, Mr. Ross E. Browne remarks that ‘‘at cer- 
tain favorably located points an extended view is obtained of the 
Forest Hill and neighboring divides. Upon losing the effect of 
the detail, one receives the impression of a general uniformity in 
the grades of the summit-lines. These summit-lines appear as 
the remaining traces of a gently undulating plain, sloping regu- 
larly from the bases of the massive peaks of the Sierra to the 
Sacramento valley.’? Extended views of the western slope of 
the Sierra Nevada may be obtained at many points from the 
Central Pacific railroad between Colfax and the summit, and they 
fully illustrate the feature referred to. 


t Auriferous Gravels of the Sierra Nevada of California, by J. D. WHITNEY. Pp. 
63-64. 

2The Ancient River Beds of the Forest Hill Divide. Tenth Annual Report of the 
State Mineralogist of California, 1890, p. 435. 


NOROGTKAPAN TOF Mie PA CIRC COAST. 37 


This uniformity of gentle slope is enhanced in some cases, 
especially in the region of the American and Yubarivers, by the 
broad, flat-topped lava flows which occupy the divides between 
the cafions. Sometimes it appears that the volcanics are thin, 
while at other places, according to Whitney their thickness is 
very large, quite often reaching 400 or 500 feet, and occa- 
sionally much exceeding that amount. The plain, however, is 
not limited to the areas occupied by volcanic rocks, but has a 
wide distribution over areas of closely folded auriferous slates, 
and cannot be attributed to the constructive effects of volcanic 
eruptions. 

Mr. Gilbert was the first to call attention to the fact that this 
uniform surface is due to erosion upon a system of plicated strata, 
and ‘could only have been accomplished by streams flowing at 
a low angle,’* in other words, the plain must have originated 
essentially as a baselevel of erosion. 

Judging from the topographic maps recently prepared for 
the geological work in the gold belt, as well as from the obser- 
vations of Whitney,” Petty,? Goodyear,” Lindgren,3 Turner, and 
myself, it appears that the inclined plateau which now forms the 
western slope of the Sierra Nevada was originally not worn 
down to so complete a plain as that already described upon the 
western side of the valley. 

Mr. Lindgren (1. c.) says, “that the Sierra Nevada, before 
the accumulation of the gravels began, was a mountain range 
greatly worn down by erosion, but not reduced to a baselevel of 
erosion. It cannot even, on the whole, be regarded as a pene- 
plain, above which isolated and more resistant hills projected. 
The declivities and irregularities of the old surface are too con- 
siderable for that, nor are the projecting hills invariably com- 
posed of the hardest rock-masses.”’ 

While some of the irregularities now recognized in the old 
plain upon the western slope of the range are due, as urged by 

tScience, Vol. 1, p. 195, March 23, 1883. 


2 Auriferous Gravels of the Sierra Nevada of California. 


3Two Neocene Rivers of California. Bull. Geol. Soc. of America, Vol. 4, p. 298. 


38 THE JOURNAL OF GEOLOGY. 


Mr. Turner, to protruding hard rocks, it is possible that a con- 
siderable portion resulted from deformation when the Sierra 
Nevada was upheaved. For it will be shown later on that since 
this peneplain was formed by erosion, the Sierra Nevada has 
been greatly uplifted, and it would be very remarkable indeed if 
in the upheaval of such an enormous mass as the Sierra Nevada 
the original plain of its western slope were not warped and 
broken. 

Platform of the interior region—The fact that the baselevel 
plain passes to the eastward from the northern end of the Sacra- 
mento valley beneath the lavas of the Lassen Peak district, sug- 
gests that it may reach the platform of the interior region, which 
is now covered by volcanic material. Within northeastern Cali- 
fornia and the adjacent portion of Oregon there are vast stretches 
of level plains which are nearly of the same altitude above the 
sea. As far as known, all the surrounding hills and mountains 
are of lava. There are no projecting peaks of older rocks, and 
their absence from wide stretches of plateau country tends to 
show a general level of the subjacent surface analogous to that 
of the interior plateau in British Columbia described by Dr. G. 
M. Dawson. 

The erosion plains we have traced upon the borders of the 
Sacramento valley, in the Klamath Mountains, upon the western 
slope of the Sierra Nevada, and probably also in the interior 
region of northeastern California, join one another in such a way 
as to show that they are simply different portions of one exten- 
sive baselevel of erosion which formerly spread over a large part, 
if not the whole, of middle and northern California and the 
adjacent portion of Oregon. What is the geological age of this 
plain of erosion? 

DEPOSITS UPON THE BORDER OF THE ANCIENT BASELEVEL. 

General statement.—In order to determine the conditions 
under which the baselevel was developed, and its age, it is 
necessary to study the formations deposited during its develop- 
ment. At the eastern edge of the baselevel, in the Sacramento 
valley, there are three formations, all of which were more or less 


TOPOGRAPHY OF THE PACIFIC COAST. 39 


influenced by it in their distribution. Only two of these, the 
middle and the lower, need here be considered. The middle 
formation is a tuff which has already been called the Tuscan 
tuff. Below the Tuscan tuff and above the Cretaceous are grav- 
els, sands, and clays, which apparently occupy the exact taxo- 
nomic position of the Ione formation of Becker, Lindgren,* and 
Turner, and may therefore be appropriately designated by the 
same name. 

Tuscan tuff—The Tuscan tuff is composed wholly of volcanic 
material. It will be considered first, for the reason that it 
can be most easily identified in different localities, and can be 
used to great advantage as a reference plane in considering the 
Tone. 

On the western border of the Sacramento valley the most 
southern exposure yet observed is on Thomes creek, four miles 
east of Paskenta. From this point it has been traced with vary- 
ing thickness for fifty miles across all the streams, cutting the 
eastern margin of the baselevel from Elder creek to Redding. 
It continues, with interruptions, around the northern end of the 
Sacramento valley to the thick deposits of similar material in the 
Lassen Peak region. It thins out to the westward and laps over 
on the baselevel in such a way as to indicate that the baselevel 
was formed before the great volcanic eruption which gave birth 
to the tuff. 

Tone formation.—Beneath the Tuscan formation lies the Ione, 
which rests upon the upturned and eroded edges of the Creta 
ceous (Shasta-Chico) strata with conspicuous unconformity. In 
the Bald Hills region, northeast of Paskenta, it is composed of 
clay, and thins out rapidly to the westward against the edge of 
the baselevel. Farther northward the formation thickens some- 
what, and contains much gravel, but everywhere it thins out rap- 
idly to the edge of the baselevel. In the Lassen Peak region, 
beneath the lava, it has its greatest development, and is many 
hundreds of feet in thickness. To the northeastward it borders 


_ ‘Geological Atlas of the United States. Text accompanying the Sacramento 
sheet. 


AO IVeAE JO UIRIMVL (OWE (CAB OUL OG, 


upon the baselevel of the Klamath Mountains, while in the oppo- 
site direction it appears to stretch up to the high plateau at the 
northern end of the Sierra Nevada, and shows the features 
already noted of tapering abruptly to the edge of the baselevel 
plain. This formation might be considered a fringe to the base- 
level, and evidently was deposited at least in part during the 
baselevel period. 

The earlier auriferous gravels upon the slopes of the Sierra 
Nevada are older than the volcanic flows of the same region. 
They are regarded by Messrs. Turner and Lindgren and the 
writer as of essentially the same age as the Ione formation in 
the Great valley of California. The auriferous gravels were 
accumulated and deposited upon the flanks of the range, while 
the finer material, sand and clay, were carried into the Sacra- 
mento valley. 


AGE OF THE BASELEVEL OF EROSION. 


The age of the baselevel must be determined by reference 
to the formation with which it is associated. It is evidently of 
more recent origin than the Cretaceous, since it truncates the 
upturned edges of the Shasta-Chico series, and these are the 
youngest strata upon which it has yet beenseen. It was already 
developed at the time the earlier auriferous gravels were 
deposited, for they lie in the broad shallow valleys which belong 
to the baselevel plain. The erosion by which it was developed 
therefore occupied a part or the whole of the time interval 
between the upheaval of the land at the close of the Chico 
epoch (Cretaceous ) and the deposition of the auriferous 
gravels. 

The age of the earlier auriferous gravels has not yet been 
fully determined, although they have been the subject of much» 
investigation. That of the later gravels will not be considered 
here. Professor J. D. Whitney, in his ‘‘Auriferous Gravels of 
the Sierra Nevada of California,’ page 283, says: ‘‘It appears 
probable, on stratigraphical grounds, that the detrital beds over- 
lying the bed rock of the Sierra Nevada represent the whole 


MOTO GEA INNO, ii A Cll On GOA ST: 41 


Tertiary period, that is, that they have been forming since the 
beginning of that epoch.* . . . The evidence of the geological 
age of the gravel deposits afforded by the plants found in the 
sedimentary beds underlying the latest eruptive masses in the 
mining region of the Sierra has already been discussed by Mr. 
Lesquereux. He distinctly recognizes the presence in this flora 
of forms identical with or closely allied to those of the Miocene; 
but still calls the age of the group Pliocene. Something of the 
same kind seems to be legitimately inferred from the animal 
forms of the same deposits. There are certain fossils which have 
been found only in deep-lying gravels like those of Douglas 
Flat and Chili Gulch. No traces of the rhinoceros, the elothe- 
rium or the small equine animal referred with doubt by Leidy 
to Merychippus have ever been found in deposits which could 
by any possibility be proved to be more recent than the basaltic 
overflow. It is true that the evidence thus far collected is but 
fragmentary. Still, taking it for what it is worth, it may be said 
that the affinities of these animals found in these lower deposits 
would indicate a Miocene rather than a Pliocene age. There 
are also, it is believed, stratigraphical reasons for admitting 
that some at least of the deposits containing these older fossils 
may be proved by other than paleontological evidence to belong 
to an older series than those strata which, though anterior to the 
basalts, yet contain a fauna decidedly mere Pliocene than Mio- 
Cee tn Character,” 

A collection of plants made from the older auriferous gravels 
upon the northern end of the Sierra Nevada was examined by 
Professor Lesquereux, who reported that their relation is evi- 
dently to the Miocene (U. S. Geological Survey, Eighth Annual 
Report, p. 419). Professor L. F. Ward, who examined the same 
collection, agreed that they were Miocene, most likely upper 
Miocene. 

Recently the evidence afforded by the plant remains has been 


* By the Geological Survey of California the Tejon was regarded as Cretaceous. 
Paleontology, Vol. 2, p. xiii. It is now regarded as Eocene, and in Oregon lies uncon- 
formably on the Shasta-Chico series. 


42 THE JOURNAL OF GEOLOGY. 


ably reviewed by Professor F. H. Knowlton, who studied exten- 
sive collections from the auriferous gravels of Independence 
Hill, Placer county, California. He concludes that the gravels 
are probably upper Miocene in age." 

On stratigraphic grounds the auriferous gravels are regarded 
as contemporaneous with the Ione formation of the Sacramento 
valley, but here, too, as in the earlier auriferous gravels, the 
fossil plants and shells appear to indicate that they belong to the 
Miocene. 

That the approximate baselevel reached its greatest develop- 
ment about the time the earlier auriferous gravels were deposited 
is indicated by the fact that they lie in the broad shallow valleys 
of that plain. The present tendency of the organic evidence con- 
tained in the flora of these gravels is to indicate that their deposition 
took place during the Miocene, most likely later Miocene. The 
erosion necessary to develop the baselevel out of the topography 
resulting from the uplift at the close of the Shasta-Chico period 
must have occupied a long interval of time, possibly beginning 
in the latter part of the Cretaceous and continuing through the 
Eocene and earlier portion of the Miocene, but as the plain 
appears to have attained its maximum extent during the Miocene, 
it may be referred to as the Miocene baselevel. 


THE ELEVATION INDICATED BY THE FLORA OF THE AURIFEROUS 
GRAVELS. ; 


The flora of the region indicated by the remains found in the 
earlier gravels is of special interest on account of its bearing on 
the topography. Numerous fossil leaves have been found in the 
early auriferous gravels about the northern end of the Sierra 
Nevada at Mountain Meadows, near the summit of Spanish Peak 
and elsewhere on the very crest of the Sierra, at altitudes ranging 
from 2,900 to 6,350 feet above the sea. These plants were 
studied by Professor Lesquereux, who recognized among them 
three kinds of figs and a large number of lauraceous plants, with 
other forms of similar significance. Not a single species of pine 


*U. S. Geological Survey, Bulletin 108, page 104. 


INOVPOGIRATAEISE (UE IIEIR, JAM CTODME (OVS Ts 43 


or fir, such as constitute the prevailing arboreal vegetation of 
that region to-day was,recognized in the collections. 

In answer to a question concerning the climatic conditions 
of that region during the Miocene, as indicated by this flora, 
Professor Lesquereux stated that ‘““by the presence of a large 
number of Laurinee the flora becomes related in its general 
characters to that of a region analogous in atmospheric circum- 
stances to Florida.’’ With this view Professor Lester F. Ward 
fully agrees, and also Mr. F. H. Knowlton, who has lately given 
much attention to the flora of the auriferous gravels. 

Mr. Knowlton, says ‘‘ Lesquereux, as already stated, argued 
that the presence of a large number of lauraceous plants indi- 
cated a region analogous in atmospheric circumstances to Florida. 
From my own studies, which embrace a much larger amount of 
material than Lesquereux had, I am not only prepared to accept 
this statement but to show that it was even stronger than he 
could have made it out.” 

Florida is a comparatively low country, rising nowhere more 
than a few hundred feet above the sea, and it is reasonable to 
infer that during the early gravel period northern California, 
which was then analogous in atmospheric circumstances to 
Florida, could not have been a region of high snow-tipped 
mountains as it is to-day. 

It is well known that during the Miocene tropical conditions 
_extended much farther north than now, and under such circum- 
stances it is possible that certain forms of plants may have had 
considerably greater range in altitude than their relatives in 
California have to-day. 

No doubt the Sierra Nevada existed at that time, but was a 
very low range, at least in the northern portion, as compared 
with its present altitude. Yet it was high enough to supply the 
alder, birch, poplar, and willows, as well as the few pine leaves 
lately found by Mr. Turner.’ 

The evidence afforded by the flora of the region is in com- 
plete harmony with the inference drawn from the topographic 


t Bulletin Philosophical Society of Washington, Vol. 11, p. 391. 


44 TTL fOORNAIE VOLS G1ALO LO GNA 


relations, namely, that during the Miocene the country was a 
series of plains and peneplains with low mountain ranges, or in 
other words, the country was but little above its baselevel of 
erosion. In no other position could such extensive plains have 
been formed by erosion. 


GEOGRAPHY OF NORTHERN CALIFORNIA DURING THE MIOCENE. 


The Ione formation being well stratified was evidently laid 
down in a body of water having a distribution at least as 
extensive as the formation itself. In the Sacramento valley, 
as far north as Marysville Buttes, the water of the bay was 
salt, as shown by the marine shells found at that point by Mr. 
Lindgren.* 

Upon the borders of this bay, at Ione, where the conditions 
were favorable for the accumulation of the vegetable matter to 
form lignite, the water was regarded as fresh or brackish. Far- 
ther northward only unios have been found, and the water in 
which the Ione formation originated was fresh. Beyond the 
Lassen Peak region in northern California the water was undoubt- 
edly fresh, but whether one large lake or a series of lakes, or a’ 
water body connected directly with that of the Sacramento val- 
ley as an estuary from the sea, is a matter of doubt. 

From the Great valley the sea swept across the region of the 
Coast Range, perhaps near the latitude of Sacramento, and 
extended northward over the area of the broad belt of sand- 
stones upon the western slope to beyond Humboldt Bay. The 
borders of the land must have been low and swampy to make 
the conditions favorable for the accumulation and preservation 
of vegetable matter to form coal. The Sierra Nevada and 
Klamath Mountains themselves were low, with gentle slopes as 
compared with those of the present ranges, and the streams 
flowed down their flanks in broad, shallow valleys instead of in 
deep cafions as they do now. 


*Geologic Atlas of the United States, text accompanying the Sacramento sheet. 
See also U. S. Geological Survey Bulletin,No. 84, by W. H. Dat and G. D. Harris, 


p- 197. 


OPO GIRARLINAOL DE PACING \GOAST 45 


DEFORMATION OF THE BASELEVEL. 


It is evident that since the Miocene there have been great 
changes of level in northern California, for instead of the original 
baselevel of the erosion, we have now prominent mountain 
ranges, whose sides are furrowed by the deep cafions of the 
rejuvenated streams. 

The deformation of the baselevel may be studied along two 
lines of evidence: (1) by tracing the present variations of alti- 
tudes in the original baselevel, which must have had a very 
gently sloping surface itself, and (2) by tracing the deformation of 
the Ione deposit which, when laid down, must have been below sea 
level at a lower altitude than the baselevel, because deposited in 
the water body upon its border. Each line of evidence should 
corroborate the other and render conclusions concerning the 
deformation more trustworthy. 

It is impossible to tell from what is known at present the 
original inclination of the baselevel. It is evident, however, 
that it must have been considerably less than one degree, for at 
that angle streams generally erode their beds much more than 
their banks, and cut cafons. 

Upon the western edge of the baselevel, at the foot of the 
Klamath Mountains in Tehama county, the altitude is nearly 2,300 
feet, while upon the eastern edge it is considerably less than 
1,000 feet, giving the old plain in the Greasewood hills a slope 
of 100 feet to the mile to the eastward. Across this plain the 
present streams flow in cafions 300 to 400 feet deep, and they 
dre still enttings line “canons, in) )seneralyyane deepest to the 
westward and gradually run out to the Sacramento river in the 
newer deposits which fill the valley. It is evident that since the 
baselevel was formed, it has been affected by differential eleva- 
tion in the uplifting of the Coast Range and Klamath Mountains, 
just north of the fortieth parallel, to the extent of over 2,000 feet, 
and if we may judge from the traces of the baselevel seen at 
Shower’s pass and South Fork Mountain, the upheaval in the 
Klamath Mountains has been much greater. It has long been 


40 THE JOURNAL OF GEOLOGY. 


maintained by Whitney and others that the principal upheaval of 
the Coast Range occurred at the close of the Miocene. 

At the northern end of the valley the elevation of the base 
level is 800 feet. To the eastward it rises gradually to 1,300 and 
1,700, and finally in the neighborhood of Round Mountain to 
2,500 feet, showing elevation in the Lassen Peak and Sierra 
Nevada region east of the Sacramento valley. 

Mr. G. K. Gilbert” was the first to recognize the broad plateau 
upon the western slope of the Sierra Nevada as a plain of erosion, 
and discussed the matter in such a way as to show that the height 
of the range has been considerably increased since the erosion 
plain was formed. 

Professor LeConte advocated essentially the same view. He 
says :* “The rivers, by long work, had finally reached their base 
levels and rested. The scenery had assumed all the features of 
an old topography with its gentle flowing curves. At the end of 
the Tertiary came the great lava streams running down the river 
channels and displacing the rivers ; the heaving up of the Sierra 
crust block on its eastern side, forming the great fault-cliff there, 
"and transferring the crest to the extreme eastern margin; the 
great increase of the western slope and the consequent rejuve- 
nescence of the vital energy of the rivers ; the consequent down- 
cutting of these to form the present deep cafions and the result- 
ing wild, almost savage, scenery of these mountains.” 

The observations of Mr. W. Lingdren3 in the region of the 
Yuba and American rivers upon the western slope of the Sierra 
Nevada, ‘‘appear to prove that the grades of the remaining 
Neocene gravel channels are to a certain extent determined by 
the directions in which they flowed, in such way as to strongly 
suggest that the slope of the Sierra Nevada has been consider- 
ably increased since the time when the Neocene ante-volcanic 
rivers flowed over its surface. It finally appears probable, from a 
study of the grade curves of the remaining channels, that the 

tScience, Vol. 1, March 23, 1883, pp. 194-195. 


2 Bull. Geol. Soc. of Am., Vol. 2, pp. 327, 328. 
3 Bulletin of the Geological Society of America, Vol. 4, p. 298. 


TOPOGRAPHY OF THE PACIFIC COAST. 47 


surtace’ of the Sierra Nevada has been deformed during this 
uplift, and that the most noticeable deformation has been caused 
by a subsidence of the portion adjoining the Great valley rela- 
tively to the middle part of the range.” 

Strong evidence of the deformation is furnished by the dis- 
tribution of the Ione formation. As already shown, this forma- 
tion was deposited about sea level. On Little Cow creek it now 
occurs at an altitude of 3,400 feet, and on Bear creek about 4,000 
feet above the sea, indicating conclusively that since the base- 
level period the Lassen Peak region has been elevated at least 
4,000 feet. There are indications that the elevation was still 
greater to the southward about the northern end of the Sierra 
Nevada, for between Mountain Meadows and Diamond Peak 
opposite Susanville the auriferous gravels supposed to belong to 
the estuarine Ione formation rise from 5,000 to 7,000 feet. These 
high gravels upon the northeastern block of the Sierra Nevada 
have been displaced in a remarkable manner by the upheaval of 
the range. The area occupied by them is about Io x 16 miles 
in extent. Although the gravels cover the larger part of this 
area and are connected throughout, they do not appear over the 
whole of it. There were a few small islands of older rocks 
during at least the later portion of the gravel period, and at 
some other places within the area the gravels have either been 
washed away or covered up by later volcanic flows. 

During the later part of the gravel period in that region, 
after the effusion of the andesitic lavas, more or less well defined 
beaches were formed around a series of volcanic islands upon 
what is now the very crest of the range from Fredonia Pass 
northeast of Mountain Meadows to Diamond Mountain. When 
developed, these beaches must have been at the same level ina 
body of standing water, but now they gradually rise to the south- 
ward from about 5,000 feet near the northern end of Mountain 
Meadows to 7,000 feet opposite Diamond Peak, and it is evident 
not only that the northern end of the range has been elevated 
but that the amount of elevation increased to the southward. 
The general inclination of this body of gravels toward Lassen 


48 DLE fLOUTKINALL OFM GEOL OGN- 


Peak, beneath whose lavas it disappears, makes it very probable 
indeed that they are connected with the Ione formation that dis- 
appears under the opposite edge of the same lavas bordering 
upon the eastern side of the Sacramento valley. If this could be 
definitely established it would show that the northern end of the 
Sierra Nevada has been elevated 7,000 feet since the gravel 
period of that region. It is possible that the increased elevation 
does not extend far to the southward, for beyond the 4oth par- 
allel the eastern crest of the range retreats to the escarpment of 
the main block of which the Sierra Nevada is composed. 

In connection with the upheaval of the northeastern portion 
of the range a fault was formed along the eastern base at least 
beyond Honey Lake. A short distance above Janesville the 
gravels are displaced by a fault in which the throw is about 3,000 
feet. On the very crest of the range, seven miles northwest of 
Janesville, the gravel rises to 7,400 feet, while at the foot of the 
steep slope which it caps the same gravel occurs in Mr. Weisen- 
berger’s mine at an elevation of about 4,300 feet. To the north- 
westward the fault runs out apparently in a monoclinal arch, later 
than the volcanic eruptions on the crest of the range at that 
point,* but before the final eruptions of the Lassen Peak region 
were completed. Mr. Lingdren has shown? that further south 
the eastern slope of the range was formed before the eruption of 
the andesitic lavas. There is some evidence of a similar 
character in the Honey Lake Region. 


ORIGIN OF THE EARLIER AURIFEROUS GRAVELS. 


The Tejon epoch appears to have been brought to a close, 
and the Niocene initiated, in northern California, without any 
marked change of level, unless a general subsidence,3 so that the 
influences in operation during the Tejon continued into the 
Miocene. The old streams still carried on their enfeebled- 
erosion, and in some places the land was completely reduced to 

tSee also Eighth Annual Report U. S. Geological Survey, p. 429. 


2 Bull. Geol. Society of America, Vol. 4, pp. 257-298. 
3DaALL and Harris: U.S. Geol. Survey, Bull. 84, p. 278. 


TOPOGRAPHY OF THE PACIFIC COAST. 49 


baselevel. The removal of material was chiefly by solution, 
and the insoluble residuary material thus set free by the disin- 
tegration of the rocks accumulated to considerable depths upon 
the land. 

The long period during which the land of northern California 
remained comparatively stationary, and which enabled the 
streams in many parts of that region to practically complete 
their cycles of erosion from youth to old age, was brought to a 
close by the initiation of an orogenic movement which generally 
increased the grade of the streams upon the western slope of the 
Sierra Nevada. At first the differential change of level was very 
moderate and increased the declivity of the streams but little, 
but being long continued it became in time revolutionary in its 
effects, and finally, accompanied by extensive volcanic eruptions, 
gave birth to the High Sierra of to-day with the deep cafions 
upon its western slope. 

The first result of this change of slope was to rejuvenate the 
streams and invigorate erosion. On account of surface deforma- 
tion which must have accompanied the upheaval of such a large 
mass as the Sierra, the stream grades would be differently affected 
even along the same channel, and in fact, as Mr. Lindgren has 
pointed out, in at least one case, owing to direction of flow, the 
stream grade has been not only diminished but reversed." 

The country being covered by a thick coating of soft residu- 
ary material, of which the great mass was fine particles, erosion 
was easy. There were coarser fragments of quartz, largely vein 
matter, as well as boulders of disintegration which had withstood 
the chemical changes. The streams readily became loaded not 
only to their full capacity but overloaded with the mass of fine 
material, and were thus forced to deposit the coarser particles. 
The grains and fragments not quite suspendable under the condi- 
tions of load were rolled along the bottom and rounded by 
attrition. 

In this way the old channels of the baselevel period became 
filled with gravel of which by far the larger part is quartz. In 

t Bul. Geol. Soc. of Am., Vol. 4, p. 281. 


50 LTE JO CLNATL OP NGRPOLOG NY: 


the same way the gold, being heavy, and associated with the 
quartz originally, accumulated in the same channels, while the 
fine light detritus was carried directly to the Sacramento valley. 

In his paper on the ancient river beds of the Forest Hill 
divide,t Mr. Ross E. Browne classifies the auriferous gravel chan- 
nel systems into three periods. The first period was prior to the 
first important flow of volcanic cement, the second was contem- 
poraneous with the series of volcanic cement flows, and the third 
following immediately after the last important flow of volcanic 
cement extends to the present time. He has called attention to 
the predominance of quartz gravel? and sand in the ancient chan- 
nels of the first period,and remarks that ‘‘ quartz is the only impor- 
tant material contained in the belts (of slates) which is hard and 
permanent enough to resist the destructive action of the current.” 
This is especially true when the auriferous slates are disintegrated. 
It is possible therefore that the predominance of quartz in the 
earlier gravels may indicate an earlier period in which the slopes 
had less declivity and disintegration exceeded transportation.3 
The fact that in the Light’s cafon region of Plumas county the 
gravel is underlain by a sheet of residuary material which was 
formed before the deposition of the gravel is evidence in the 
same direction. Furthermore, the sand deposited with the gravel 
is rough, angular and unassorted, such as is derived from residu- 
ary material near at hand, and records a period of gentler decliv- 
ity during the next earlier epoch. 

The old channels of auriferous gravel of the first period are 
in a measure characterized by the large size of the deposits. Ross 
E. Browne states:+ ‘(In a general way it may be said that the 
channels of the second period differ from those of the first as 

« Tenth Annual Report, State Mineralogist of California, 1890, pp. 437-439. 


2 See also J. D. WHITNEY’s Auriferous Gravels of the Sierra Nevada, page 323, who 
says “that in some localities the gravel is almost entirely made up of quartz boulders 
and pebbles.” 


3 Mr. BAILEY WILLIS some time ago, in his study of the Appalachian region, came 
to a similar conclusion, yet unpublished, to account for the predominance of quartz 
pebbles in the conglomerate at the base of the Coal Measures. 


4 Tenth Annual Report State Mineralogist of California, pp. 439-441. 


ORO GTRATTINGOL NEE PA CELE COAST. 51 


follows: their beds are narrower, rims steeper, and accumula- 
tions of bed rock gravel incomparably smaller.” In these large 
accumulations of older gravels Prof. Whitney saw evidence of 
larger streams and heavier precipitation during the gravel period 
than now belongs to that region,’ but, as pointed out by Mr. 
Gilbert,? deposition in stream channels is indicative of diminished 
instead of increased rainfall. 

Professor Le Conte regarded the gravels as ‘‘ deposits made by 
the turbulent action of very swift, shifting, overloaded currents” 
supplied with both water and debris ‘by the rapid melting of 
extensive fields of ice and snow”’ which were then supposed to 
occupy the higher portion of the range. 

A very important contribution to the literature of the aurifer- 
ous gravels has been made lately by Mr. W. Lindgren, whose 
views are expressed in the following quotation :+ 


“From the rugged country in the region of their sources the rivers pursued 
their course down in broad valleys separated by ridges which even in the 
lowest foot-hills sometimes reached an elevation of a thousand feet above the 
channels. The outlines of the ridges were usually comparatively gentle and 
flowing ; still, slopes of ten degrees from the channel to the summit were 
common and slopes as high as fifteen degrees occurred in the eastern part of 
the Sierra. The character of a region of old and continued erosion, com- 
mencing probably far back in the Cretaceous period, is everywhere plainly 
evident. Inthe center of the deep depressions is quite frequently found a 
deeper cut or “‘ gutter,” indicating a short period of more active erosive power 
just before the beginning of the gravel period. At this time, probably about 
the beginning of the Miocene period, the streams became charged with more 
detritus than they could carry and began to deposit their load along their 
lower courses, especially at places favorably situated, as, for instance, along 
the longitudinal valley of the South Yuba. Toward the close of the Neocene, 
gravels had accumulated all along the rivers up to a (present) elevation of 
about 5,000 or 6,000 feet ; above this it is plain that erosion still continued in 
places with great activity and furnished some of the material deposited in the 
lower parts of the streams. The coarse character of much of the gravel and 

* Climatic Changes in later Geological Times, p. 1. See also Auriferous Gravels, 
Pp. 335. 

2 Science, Vol. I., p. 194, March 23, 1883. 

3 Am. Jour. Sci., Vol. X1X., 1880, p. 184. 

4 Bul. Geol. Soc. of Am., Vol. 4, pp. 265-6. 


52 THE JOURNAL OF GEOLOGY. 


the often remarkable absence of fine sediments in the beds point clearly toa 
somewhat rapid stream capable of carrying off a great deal of silt, and the 
accumulations are probably due to rapid overloading rather than to low 
grades of the rivers. The deep channels were filled and the gravels 
encroached on the adjoining slopes, where they were deposited in broad 
benches. A maximum thickness of 500 feet of deposits was attained on the 
South Yuba, and of from 50 to 200 feet in the other parts of the lower rivers. 
In the lower and middle Sierra some of the rivers then meandered over flood- 
plains two or three miles wide, above which the divides of bed-rock rise to a 
height of several hundred feet. In some instances low passes over divides 
were covered, and temporary bifurcation and diversion of rivers into adjoin- 
ing watersheds occurred.” 


It is evident from the facts already known that at the time the 
early gravels were deposited the northern end of the Sierra 
Nevada was not less than 4,000 feet lower than at the present 
time, and that its climatic circumstances as indicated by its flora 
were not such as to give rise to either glaciers or extensive fields 
of snow.’ For this reason it is necessary to appeal to some other 
cause than glaciers as the source of the great mass of debris 
deposited in the old auriferous gravel channels, and in view of the 
facts herein cited, the writer suggests that a source may be found 
in the large mass of residuary material upon the surface at the 
beginning of the gravel period. There is evidence, as already 
shown, that at the close of the Tejon disintegration exceeded 
transportation, and residuary deposits accumulated upon the gentle 
slopes of the land to considerable depths. This condition appears 
to have continued during the early Miocene. The depth of dis- 
integrated rock would vary greatly with different formations. 
Upon the diorite and other rocks containing minerals subject to 
ready alteration it would be deepest, and their surfaces, at least 
in the case of the diorite, would be strewn as to-day with large 
and small boulders of disintegration. The quartz veins which 
intersect these rocks and the silicious slates would be but little 
affected. The gold not enclosed in quartz veins* would be set 
freee 


See also WHITNEY’S Auriferous Gravels, p. 295. 


? WHITNEY’s Auriferous Gravels, p. 352. 


MOP OGIRAILIA NW. (OF HIGIS SEA CIGD (COVA SIE: 53 


If, when thus mantled with residuary material, the Sierra 
Nevada region were affected by a change of level in such a way 
as to slightly increase the fall of the streams upon its slopes, it is 
believed, as already suggested, that during a comparatively brief 
period owing to overloading they would be forced to deposit and 
fill their channels. A portion of the process is, in a measure, 
illustrated by what has taken place along some of the present 
streams of the Sierra Nevada where hydraulic mining has been 
extensively carried on. The streams are overloaded by the 
debris forced into them from the mines and their channels are at 
least temporarily filled with gravel. 

After the deposition of the earlier gravels the declivity of 
some of the streams at certain points appears to have been so 
decreased that they deposited finer material and covered the 
gravel with sand and clay. This may have resulted from differ- 
ential elevation, differential subsidence, or both, and there 1s 
evidence that both occurred within the gravel period. At Cherokee 
Flat upon the eastern border of the Sacramento valley the finer, 
essentially estuarine deposits, over 300 feet in thickness, lap over 
to the eastward upon the ancient river and shore gravels mined 
at that place. This overlapping evidently resulted from a subsi- 
dence of that region. : 

SUMMARY. 

A study of the ancient topographic features upon the bor- 
ders of the Sacramento valley, in the Klamath Mountains, and 
upon the western slope of the Sierra Nevada, shows that during 
the earlier portion of the auriferous gravel period, southern 
California, by long continued degradation, was finally reduced 
approximately to baselevel conditions. The mountain ranges 
were low, and the scenery was everywhere characterized by 
gently flowing slopes. 

The distribution of the Ione formation and the early aurit- 
erous gravels, as well as the plant remains which they contain, 
point clearly to the same conclusion. 

The topographic revolution consisted in developing out of 
such conditions the conspicuous mountain ranges of to-day. 


¢ 


54 LEE VOU RINA LE OLR GLAO TOG. 


The northern end of the Sierra Nevada has since been raised at 
least 4,000 feet, and possibly as much as 7,000 feet, and a fault 
of over 3,000 feet developed along the eastern face of that por- 
tion of the range. The Klamath Mountains may in some por- 
tions have experienced at the same time an equal upheaval. 
From all sides the amount of uplift decreased rapidly toward 
the Sacramento valley. 

In the initial part of this revolution the earlier quartzose aurif- 
erous gravels were formed. The source of their material was 
found in the thick deposits of residuary detritus which had 
accumulated upon the surface of the land during the baselevel 
period. This large accumulation of disintegrated rock sub- 
stance rendered the loading of the streams so easy that when 
rejuvenated by orogenic movements they became overloaded and 
filled their ancient channels with auriferous gravels." 

Jo So /Diivicig. 


U. S. GEOLOGICAL SURVEY, Washington, D. C. 
December 12, 1893. 


«Since this paper was written a very important one has been published by Prof. 
A. C. Lawson, on the Post-Pliocene Diastrophism of the Coast of Southern Calfornia. 
University of California, Bulletin of the Department of Geology, Vol. I., No. 4, 


pp. 115-160. 


THE NAME “NEWARK” IN AMERICAN 
SIMRAN GI RUIN 2 


AX WO IND ID) ACISKS WHS) SILO) ANT. 


Ite 


Mucu time and ink have been wasted in discussing the claims 
of alternative stratigraphic names. In many instances contro- 
versies arise over questions of fact, but there are also numerous 
cases in which the facts are well understood, and individuals dis- 
agree only as to the bearing of the facts on the questions of 
nomenclature. Opinions differ so widely as to the principles 
which should determine the selection of names that facts which 
some regard as conclusive appear to others not at all pertinent. 
The road to ultimate peace lies through a war of principles; and 
the valuable controversy is one in which the fundamental postu- 
lates of the contestants are exposed. Holding this view of the 
general question, I would be understood as joining in the discus- 
sion of the term ‘‘ Newark” only because a principle of strati- 
graphic nomenclature appears to be involved. 

Iinvas recent article B. S. Lyman says: 

“For those rocks have, from their conformability throughout, and their 
predominant color, and a comparative lack of fossils through a great part of 
them, been commonly lumped together as only a single group, formation, or 
system, under the general name of New Red, or Triassic, or Jurassico- Triassic, 
or Rheetic. Nearly forty years ago, with the bold assurance born of ignorance, 
perhaps quite pardonable at that time, the special name of Newark group 
was proposed for the whole lot, from one of its most striking local economic 
features, though otherwise an extremely subordinate one, and even economi- 
cally perhaps inferior to the Richmond coal ; and latterly there has been an 
effort to revive the name, long after it had fallen into well-merited oblivion.”* 

I am one of those who have seconded Russell’s proposal to 
revive the name ‘“Newark,’? and despite the brief argument 

= Proc. Am. Phil. Soc., Vol. 31, p. 314. 


2 Am. Geol., Vol. 3, 1889, pp. 178-187. 
55 


56 TE OURINAVE \OLNG EOL OG Ne 


which accompanies Lyman’s protest, I am at present of opinion 
that the needs of geologists are better served by Newark than by 
New Red, Jurassic, Jurassico-Triassic, or Rhetic. 

It may be assumed that there is no difference of opinion as 
to the propriety of giving local geographic names to the minor 
stratigraphic units. Such is the modern practice of most geo- 
logical surveys, and it has the sanction of the International Con- 
gress of Geologists. Lyman, too, in the paper cited, introduces 
Pottstown shales, Lansdale shales, Norristown shales, Perkasie 
shales and Gwynedd shales as the names of newly recognized 
formations in eastern Pennsylvania and the contiguous parts of 
New Jersey, deriving the distinctive word in each case from the 
local geography. The stratigraphic units thus distinguished are 
all parts of the larger unit to which Redfield euplice the local 
geographic name ‘“‘ Newark.” 

But Lyman protests against the use of the local name for the 
larger unit. It is not entirely clear to me whether he holds that 
the larger unit should have no name, or that it should not have a 
local name, or only that it should not receive the particular local 
name; and I therefore find it easier to state the basis of my own 
opinion than to discuss his view. 

1. In my opinion the larger unit should have an individual 
name.—\n the nomenclature of stratigraphy, as in language gen- 
erally, it is advantageous to avoid paraphrases by giving a short 
name to every concept which needs frequently to be expressed. 
That for which Redfield proposed the name ‘“‘ Newark group”* is 
a stratigraphic integer, so definitely limited in nature that its 
individuality has been recognized in the literature of a half cen- 
tury. In the paper just referred to it is distinctly recognized by 
Lyman, who calls it in one place “ the older Mesozoic rocks of 
New Jersey,” and elsewhere ‘“‘ the older Mesozoic,” ‘‘ the so-called 
New Red,” ‘the New Red beds,” “the New Red.” Each of 
these terms is used as a name rather than as a description; even 
the long phrase ‘“‘the older Mesozoic rocks of New Jersey ” is 
not a definition, for it is made to cover rocks, for example, the 


t Am. Jour. Sci., 2nd ser., Vol. 22, 1856, p. 357. 


THE NAME “NEWARK” IN AMERICAN STRATIGRAPHY. 57 


Richmond coal, which are not in New Jersey. The unit is pecul- 
iarly definite in that its lower and upper limits are marked by 
conspicuous unconformities, while its strata are everywhere con- 
formable with one another. Its composition, though not uni- 
form, is so little varied that attempts to unravel its stratigraphy 
and structure have been successful in but few districts. 

2. The name should include a local geographic term.—In the 
nomenclature of historic geology there are two parallel sets of 
terms, the one representing larger or smaller bodies of strata, the 
other representing larger or smaller divisions of geologic time. 
As the divisions of geologic time are based upon the classifica- 
tion of strata, their names have been mostly derived from 
stratigraphy, and there are many circumstances under which it is 
a matter of indifference whether a given term be construed in its 
stratigraphic or in its chronologic sense. Partly in this way 
there has arisen a widely prevalent habit of confusing strata and 
time. This confusion has an unfortunate influence on the treat- 
ment of problems of correlation, as it leads to language implying 
that the stratigraphic units of distant lands, for example, Europe 
and America, are the same. As I understand the case each por- 
tion of the general geologic time scale was based upon the strati- 
graphy of some district, usually in Europe. Correlation at a 
distance, for example, in America, does not determine the exist- 
ence in America of the European formations, but only the exist- 
ence of local formations deposited (in whole or part) in the 
same portions of geologic time. Or, in other words, correlation 
arranges the formations of a country in accordance with a 
standard time scale. 

When the time relations of a formation or other stratigraphic 
unit are unknown or are imperfectly known, a name derived from 
the time scale can be employed only provisionally. As knowl- 
edge of fauna and flora increases, opinions change as to time 
relations, and experience shows that at any stage in the accumu- 
lation of paleontologic data conflicting opinions may be held by 
- different students. Time names are thus unstable; but a geo- 
graphic name, depending as it does on simple relations readily, 


58 THE JOURNAL OF GEOLOGY. 


ascertained, is permanent. The rocks in question well illustrate 
the confusing synonomy which arises from the employment of 
time names. They have been called at various times and by 
various writers: Silurian, Old Red, Carboniferous, Lower Car- 
boniferous, Permian, Upper Permian, Mesozoic, Older Mesozoic, 
Secondary, Middle Secondary, New Red, Trias, Jura-Trias (and 
synonyms), Keuper, Upper Trias, Rhetic, Lias, Inferior Oolite, 
and Oolite. 

When the chronological relations of a stratigraphic unit have 
been established, it becomes proper to apply to it the title of any 
time division including its period of formation ; but the need for 
a local stratigraphic name, or, in other words, an individual 
name, does not cease. The place of the Hamilton group in the 
time scale is so well known that it is properly called Devonian 
and Paleozoic, but the local name Hamilton is still useful. 

In the conceivable case of a formation or group representing 
the whole of a division of the time scale and no more, there 
might be a question of the need of a localname. But the exist- 
ence of such a case has not been demonstrated, and it must be 
admitted that in the great majority of instances the local strati- 
graphic units are incommensurate with the standard time units. 
The body of rocks under consideration is imperfectly supplied 
with fossils, and little is known of the relations of its fossilifer- 
ous horizons to one another and to the upper and lower limits of 
the series. No one asserts that its period of formation was coéx- 
tensive with any of the time divisions whose names have been 
provisionally applied to it. Opinions as to the interpretation to 
be given to its fossils are still divergent, and the only name 
which can be conveniently used by all is one which avoids the 
question of correlation. A local geographic name meets this 
requirement. ; 

There are valid objections to a paleontologic or a purely pet- 
rographic name, but as such have not been proposed the objec- 
tions need not be stated. 

3. The proper geographic term 1s Newark.—Prominent among 
the qualifications of a geographic term for employment in strati- 


THE NAME “NEWARK” IN AMERICAN STRATIGRAPHY. 59 


graphy are (1) definite association of the geographic feature with 
the terrane, (2) freedom of the term from preoccupation in 
stratigraphy, (3) prierity. The rule of definite association is 
satisfied if the geographic feature, being a town or district, is 
wholly or partly underlain by the terrane, or if, being a stream, 
it crosses the terrane. Preferably the portion of the terrane 
thus associated should be petrographically and paleontolog- 
ically characteristic, but this consideration vields to priority. 
The ‘‘ Newark” rocks underlie the City of Newark, exhib- 
iting typical phases of sandstone and shale and containing 
some fossils. The only other rocks present are of widely dif- 
ferent character, being Pleistocene. The name Newark has been 
applied to no other terrane. It is the earliest geographic 
name proposed for this terrane.* 
GK, GinsEra: 


We 


Mr. GILBERT has very kindly invited me to answer his argu- 
ment: (1) that the so-called Newark system ought to have a 
name, because it is a stratigraphic integer, or unit; (2) that a 
stratigraphic name ought to include a local geographical term ; and 
(3) that the name Newark is the proper one, because of (a) the 
definite association of that geographical feature with the rock 
beds in question, (b) the freedom of the term from preoccupa- 
tion in stratigraphy, and (c) its priority. 

1. He considers that the stratigraphic unit is peculiarly defin- 
ite from the conspicuous unconformities at top and bottom, while 
internally it is conformable throughout with little varied com- 
position. 

In eastern Pennsylvania, where the rock beds have been 
studied with some small approach to thoroughness, the compo- 
sition is found sufficiently varied to justify at least five very con- 
spicuously marked subdivisions of several thousand feet each. 
Almost all the fossils hitherto used for inferring the age of the 


tSee American Geologist: Russell, Vol. 3, p. 181, and Vol. 7, pp. 238-241; 
Hitchcock, Vol. 5, p. 201. 


60 THE JOURNAL OF GEOLOGY. 


beds appear to have come from a single one of those subdivis- 
ions, one quite above the rocks of Newark, and the same that 
contains the Richmond coal. That coal, Gilbert says, does not 
occur in New Jersey, meaning, perhaps, not in large deposits 
like the Virginian; but yet no doubt it occurs there in thin lay- 
ers and traces, just as in Pennsylvania, since the same subdivis- 
ion of rock beds does extend into New Jersey. It is, perhaps, 
uncertain whether the Newark rocks, with their two reported 
fossil species, belong even to the Mesozoic. 

There is in eastern Pennsylvania and New Jersey great 
unconformity at the top and bottom of the rocks in question; 
but it is not yet so certain that beds of the same age as the low- 
est of them do not occur conformable to Paleozoic beds in west- 
ern Pennsylvania and elsewhere in eastern America, to say 
nothing of the West. 

Clearly no claim for unity in the supposed group could be 
based on geographical continuity. 

Would it not, indeed, be still more reasonable if he main- 
tained that the Paleozoic rocks of the Appalachian region were 
a stratigraphic integer or unit, and consequently deserved a sep- 
arate name? 

2. There are, in truth, strong arguments in favor of gener- 
ally giving local geographical names to stratigraphical groups, 
whether large or small. Yet there are many names of a differ- 
ent character that have had merit enough to become universally 
accepted, such as Paleozoic, Mesozoic, the Old and New Red 
Sandstones, Trias, Oolite, Calciferous, Corniferous, Saliferous, 
Carboniferous, Coal Measures, Millstone grit, Cretaceous chalk, 
Eocene and the like. Of course, the larger the group, the 
less easy to find a suitable, well-characterizing local name, the 
name of a place or region where the beds have been particu- 
larly studied, or much seen of men, or, as a whole, finely dis- 
played; and that would be a difficulty with so extensive a set of 
beds as the one in question. 

3. Gilbert, while insisting that Newark is the proper term in 
the present case, evidently admits that some such geographical 


THE NAME“ NEWARK” IN AMERICAN STRATIGRAPHY. O1 


names are more suitable than others, requiring at least definite 
association with the rock beds, freedom from preoccupation, and 
priority. 

The definite association he requires seems to be very slight ; 
namely, the occurrence at Newark of perhaps one-tenth or one- 
twentieth of the beds to be included in the name, and with 
only two determined fossil species, plants. Suppose, in rummag- 
ing among old periodicals of forty years ago, a foot-note by 
some Baltimore collector were found, suggesting, without any 
attempt at either stratigraphic or geographical delimitation, that 
the whole body of Appalachian Paleozoic rocks be called the 
Cockeysville group, because, forsooth, the Paleozoic marble 
quarries there supply the city with fine building material; would 
not the argument for the revival of the name be quite as strong 
as in the almost precisely parallel case of Newark? 

As to priority, and even preoccupation, and suitableness, too, 
is it not with geologists the same as with everybody else, that 
words, after all, are only used for the sake of being understood, 
and those words are to be used that will be most readily under- 
stood, so that currency, usage, is really the main criterion? 

—Usus 
Quem penes arbitrium est et jus et norma loquendi. 

It is a great fundamental principle, that with the lapse of 
thousands of years has become more and more firmly estab- 
lished. 

The rule of priority is an excellent one for cases otherwise 
doubtful or indifferent; but surely we should not be sticklers 
for it to the extent of raking up a name like Newark, that was 
unsuitable in the beginning, never did find acceptance, and was 
long ago wholly obsolete. 


BENJAMIN SmitH Lyman. 
PHILADELPHIA, December I1, 1893. 


A 


AN ABANDONED PLEISTOCENE RIVER CHANNEL 
IN EASTERN INDIANA. 


Rusu and Decatur counties in southeastern Indiana are at 
present drained) by, lat Wock "creek wand (@litty, vereek. = Bite 
former has its source in Henry and the latter in Decatur county. 
Both flow in the same general southwesterly direction, and 
occupy deep channels which they have eroded in the hard and 
homogeneous limestone of the Niagara age. They discharge 
their waters into the east fork of the White river, the Flat Rock 
above the City of Columbus and the Clifty below. During one 
of the later stages of the Pleistocene period, and perhaps 
extending into the recent period, these counties were drained 
by a stream whose channel had a width of forty rods and a 
depth of ten or twelve feet, as shown by its well-marked banks 
composed of coarse river gravel. The elevation of the upper 
part of this stream was thirty feet above that of the rock bed of 
the recent streams. It hada more southerly course than these, 
having its point of departure from the present Flat Rock creek 
near Rushville, and its point of union with the present Clifty 
creek near Milford. . As indicated by the map, the river may be 
described in four sections. 

I. From a point about three miles above Moscow P.O., the 
old channel, called in this region ‘‘ Hurricane,” 
a southerly course midway between the Flat Rock creek and the 
Little Flat Rock creek until it encounters the latter near the 
county line where the latter’s course is westerly. Through- 
out this stretch the old channel has an elevation considerably 
higher than the modern streams. Comparatively little water 


may be traced in 


now runs through this channel except in flood time. 
II]. From the point where the old channel encounters the 


present KittleyRlat Rock tcreekuiton 2 point about a mile below 
62 


ABANDONED PLEISTOCENE RIVER CHANNEL. 63 


the junction of the Little Flat Rock creek with the Flat Rock 
creek, the old and the new channels approximately coincide. 
The old channel has been modified and lowered to about the 
level of that of the present streams. 

III. The old channel departs from the recent channel at the 
point last described, and may be traced a little west of south to 
Milford P.O. It is about thirty feet above the recent channel ot 
the Flat Rock creek at the point of departure, and has but a 
slight fall. The Flat Rock creek, in cutting its channel toward 
the north from the point where it left this ancient river, has car- 
ried away its water supply, leaving the abandoned part of the 
old river a relatively high marshy region known to the early set- 
tlers as “ Beaver Pond.” Recently an open ditch has been cut 
through it converting it into fertile corn and wheat land. 

IV. From Milford the present Clifty creek flows through 
the old channel and has modified it, as in the case of the Little 
Flat Rock creek above mentioned. 

If the Flat Rock and the Little Flat Rock creeks existed 
contemporaneously with the old stream they, as well as Clifty 
creek, were tributaries to it at the points named as their conflu- 
ence, and doubtless flowed at the same relative level and had a 
less rapid fall than now. The evidence collected in regard to 
the bed of the old stream shows that it ran over the Niagara 
limestone in the upper part of its course with the exception of 
the region between the Flat Rock creek and Clifty creek (Sec- 
tion ITI.), where it flowed over Pleistocene deposits of consider- 
able depth as shown by well sections. One of these, just below 
the C. C. C. & St. L. Ry. (see map), penetrated sand, clay, and 
bowlder clay to a depth of 135 feet without reaching rock. 
Another, a short distance below, is seventy-five feet deep insimi- 
lar deposits without reaching their bottom. 

The facts so far observed do not show precisely when the 
stream originated nor exactly how long it continued before its 
waters were diverted into their present courses. It seems proba- 
ble, however, that it originated immediately after the retreat of 
the ice from the region, and was a part of the first definite system 


JOURNAL OF GEOLOGY. 


Pleistocene River in Eastern Indiane -Beachler, 


Scale — ,one_mile ; 


ABANDONED PLEISTOCENE RIVER CHANNEL. 65 


of drainage that developed after the ice melted away. This 
would make it originate in the closing stages of the Pleistocene 
period. From the fact that the present Flat Rock has cut its 
channel in limestone about sixty feet at St. Paul below the bot- 
tom of the old channel, it would appear that it had been essen- 
tially abandoned a considerable time ago. Why the Flat Rock 
abandoned it at Moscow, and again south of St. Omer P.O., after it 
had reunited with it, I am not prepared to say. Nor can I say 
that it may not possibly have been a subglacial channel that was 
abandoned as soon as the ice melted away and left its waters 
free to follow the lowest depression of the surface. 

The existence of the old channel north of the Little Flat 
Rock creek was first pointed out, so far as I know, by Dr. Frank 
Howard, of St. Pau!, Indiana, who also assisted the writer in 
tracing out the channel for the purpose of preparing the map. 


CHARLES S. BEACHLER. 


SUDILES. FOR STUDENTS. 


PHYSICAL GEOGRAPHY IN THE UNIVERSITY: 


The logical method in geography—sSuccess in the study of 
geography, as in‘other subjects, depends largely on the share of 
mental light with which the facts are illuminated. For example, 
during the two weeks in which my class in physical geography 
has recently been occupied with the tides, a long roll of trac- 
- ing linen has been hanging on the laboratory wall, containing 
copies of a half month of tidal curves at Honolulu, Boston, 
Philadelphia, Port Townsend (Oregon), and Point Clear, on the 
Gulf of Mexico. The essential facts of tidal oscillation are thus 
exhibited with great clearness, thanks to the kindness of Mr. 
Christie, of the U. S. Coast Survey, by whom the original records 
were selected, and under whose direction the copies were made 
for me. While these curves were illuminated only by the 
light that came in through the laboratory windows, the facts 
were but imperfectly perceived. The more peculiar variations of 
the curves involved in the diurnal inequality of tidal amplitude 
and interval could not be discovered by eyesight alone, at least 

t NoTE.—Although it was the author’s intention to prepare this essay for publica- 
tion as one of the ‘“‘Studies for Students” of this Journal, it has been unconsciously 
addressed as much to teachers as to scholars. This is perhaps excusable because of 
the little attention generally paid to physical geography in our colleges. The chief 
object of the essay is to present the plan of the author’s course in this subject, with the 
hope that it may be tried by others, and modified or extended as experience shall 
advise. It may be added that a selected list of our governmental maps of use in 
teaching has been prepared by a sub-committee of the Conference on Geography of 
the National Educational Association, and that its publication may be expected at an 
early date; that a list of grouped sheets of foreign topographical surveys, with descrip- 
tive notes, is in preparation by the author, and that a list of selected photographs and 
lantern slides is in contemplation. With these aids it will be easier than it now is to 


experiment on systematic geography in the universities. W. M. D. 


66 


SEVEN ESIICAIL (GIR ONGIRAI ZENA TON, SMEAR) (CONPLVIRI SH INE, 67 


not by the simple eyesight of such observers as are found among 
average college students. But during the same week that the 
class was examining these tidal tracings in the laboratory, and 
thereby gaining an approach to a simple inductive knowledge of 
the principal facts of the subject, the problem was taken up from 
the other side in Tectures, which discussed the theoretical conse- 
quences of the interaction of two bodies, and deduced from the 
theory of gravitation a number of special results that ought to 
OCeUii Ene MeO Ol tne) tides) 1s| correct. | As an ard! in) this 
deductive discussion, I placed three great circles of paper around 
a globe, so as to represent the theoretical arrangement of the 
tidal equator, and high tide circle and the low tide circle, and 
their relations to the latitude circles of the earth. Now, return- 
ing to the tidal diagrams with the results of the tidal theory in 
mind, it is only the poorly trained, the dull, or the stolid ‘“stu- 
dent’ who feels no mental satisfaction in the successful meeting 
of the facts of observation and the consequences of theory. 
Facts before noted, but not understood, now gain meaning ; facts 
before disconnected now fall into their natural relationships ; 
facts before unnoticed are now searched for and found, and won- 
der is even excited that they were not seen sooner. Neither 
induction nor deduction alone satisfies the mind. However full 
the series of facts, however extended the deductions from the- 
ory, both facts and deductions are of small value while they 
remain unmated. Properly confronted, they pair off and each 
one reacts on its mate most favorably. If the facts are well 
observed and recorded, if the theory is justly based and logically 
extended to its consequences, the inductions and deductions 
mutually complete each other, and the mind is satisfied. The 
window light then seems a dull illumination of the tidal tracings 
compared to the light that shines on them from the under- 
standing. 


As with the tides of the ocean, so with the forms of the land. 
They are but half seen if examined only by daylight. They are 
less than half appreciated if seen without an understanding of 


68 DEE, fOORNAE OF NGEOLOGY, 


the generalizations by which they are correlated. The more 
complete the mental scheme by which an ideal system of topog- 
raphy forms is rationally explained, the more clearly can the 
physical eye perceive the actual features of the land surface ; the 
more definitely can it record them in mental impressions. Topo- 
graphical forms are so varied, and often so complicated, that the 
outer eye alone is no more competent to detect all their intrica- 
cies and correlations than to discover all the peculiarities of the 
tidal curves. It is true that with exceptionally keen powers of 
observation, and with unusual opportunity for deliberate exami- 
nation, the unaided eye may come to see more and more of the 
ultimate facts; but these conditions are so rare that they need 
not be considered. The average eye, and the usual time allowed 
for observation do not suffice; they must be supplemented by 
the quickened insight that comes from rational understanding. 

No better confirmation of this conclusion can be found than 
in the experience of those who have to employ engineers, 
untrained in geology and geography, to make topographical 
maps. The work that such surveyors produce is rigid, mechan- 
ical, unsympathetic, inaccurate, inexpressive. If time were 
allowed them to run out all their contours by actual measure- 
ment, an exact map might be produced; but neither time nor 
money can be devoted to so slow and expensive a method. Even 
the best surveys are necessarily sketched in great part; and the 
topographer must appreciate his subject before he can sketch it. 
He must have a clear insight into its expression; his outer eye 
must be supplemented by his inner eye. Then he can make up 
a valuable, even though not an expensive, map. I do not mean 
for a moment that he is to invent and not to observe; that he is 
to make a fancy picture instead of a true likeness. My point is 
simply that the difficulty of making a true likeness is so great 
that all aids towards it must be employed ; and one of the chief 
aids to sharp outsight is clear insight. How can a clear geo- 
graphical insight be gained ? 

An analogy with the study of the tides may still serve us. 
The facts of the tides are first presented in what seems like a 


PHYSICAL GEOGRAPHY IN THE UNIVERSITY. 69 


bewildering, even an overwhelming, variety, without suggestion 
of order or meaning. While these facts are studied and classi- 
fied, let the system of the tides be deduced in accordance with 
accepted physical laws. Let the tidal theory be followed far 
enough to discover consequences so numerous and so intricate 
that they cannot be imitated by chance. Neither the inductive 
nor the deductive work should have precedence. They should 
advance together, but without confusing one with the other. 
When both processes are well advanced, let the facts be reéxam- 
ined in the light of the theory, and summon a critical judgment 
to determine how far the reports of outsight and insight agree. 
Success in such study requires that the facts shall have been 
closely observed, clearly described, and fairly generalized; the 
inductive results thus gained being held apart by themselves. It 
requires, also, that the theory shall have been logically extended 
to its legitimate consequences ; the deductive results thus secured 
being stored away in a special mental compartment. ‘Then, 
in due order, bring forth the corresponding members of the two 
classes of results, and judge of the success of the theory by the 
agreements thus discovered. 

Let the same method be applied in the study of geography. 
Set an abundant array of facts before the class in the laboratory. 
Let the facts be examined and classified as far as possible, simply 
according to their apparent features and without regard to expla- 
nation. At the same time, present an outline of a deductive 
geographical system in the lecture room. During the advance 
of the two lines of work, compare their results frequently, but do 
not confuse them. Ina few months a large array of facts may 
be examined, an extended deductive system may be developed, 
and the two may be compared in the most thorough manner. 
Every comparison aids further advance in both parts of the work. 
Both outsight and insight are cultivated. A geographical under- 
standing, based on a proper combination of many mental facul- 
ties, is aroused and strengthened. The real study of geography 
is well begun. The several steps involved in this plan of work 
may now be traced in some detail. 


70 IEEE, J OWMINAUIL, (QUE (GIEOULI OG SZ 


Introductory ulustration of facts—It is well at the outset to 
present a collection of varied geographical illustrations, in order 
to bring prominently before the mind the great variety of the 
facts with which we have to deal. At the same time, a prelimi- 
nary exercise is gained in the interpretation of different means 
of geographical representation. The following list will serve to 
indicate the class of materials from which selection may be made 
for a first week’s laboratory work : 

Heim’s model of an Alpine torrent ; Harden’s model of Mor- 
rison’s Cove, Penn., or a photograph of this model, or of Bran- 
ner’s model of Arkansas; Jackson’s photograph of the deep 
valley of the Blackwater in the plateau of West Virginia ; 
Holzel’s oleograph of the Hungarian plain; Becker’s elabo- 
rately colored and shaded relief map of the Canton Glarus, 
Switzerland; a group of contoured map sheets, as the twelve that 
embrace the Berkshire plateau and the Connecticut valley in 
western Massachusetts, mounted as a wall map for better con- 
venience in study ; a hachured map, such as that of the Scotch 
Highlands, in a group of sheets of the British Ordnance Survey, 
also mounted as a wall map; a tinted relief map, as of New Jer- 
sey, from the topographical atlas of that state, etc., etc. 

The need of the systematic study of geography is apparent 
from the difficulty that most students have in expressing the facts 
portrayed in these various illustrations. Words are not easily 
summoned to describe them. Many of the illustrations are ona 
much larger scale than is commonly employed in atlases, and the 
ordinary accounts of direction and distance usually employed 
in describing similar maps, are at once felt to be insufficient to 
express the varied reliefs here exhibited. How can the student 
best approach a perception and an understanding of the facts 
before him and at the same time gain an ability to describe them 
in fitting language ? 

Insufficience of inductive study—Vhe ordinary fund of geo- 
graphical terms does not suffice to describe good maps and mod- 
els with sufficient exactness. Further than this, a few questions 
from the instructor will show that many facts plainly set forth 


LEO GSICAUE, (GIR OCIA ZITO TIN, WEIR (CIN WIBISH TONG, Tal 


are not seen at all. Interpretations and correlations are not even 
suspected. This is perfectly natural when it is remembered that 
most college students have never been taught to observe closely 
or to express themselves clearly in well chosen words. It is 
still more natural when it is remembered that the little knowl- 
edge of geography that they have brought from school is hardly 
more than a confused memory of an unsystematic, empirical text 
book. Whether their observation is directed to the semblance 
of facts in maps, views, and models, or to the actual facts of out- 
door nature, observation is attempted only with the outer eye; 
PMieminnehreyeuMassmever been opened, Die idea, that! alll the 
forms of the land are systematically developed has never been 
implanted in their minds. They possess no general and well 
tested deductive understanding of the development of land 
forms, no system of terrestrial morphology. The facts of obser- 
vation excite no harmonious response from the corresponding 
members of a deductive geographical scheme. 

While the study of geography remains in this incomplete and 
illogical condition, it is a blind study, although it is carried on 
chiefly through the eye. While the life of the features of the 
earth’s surface is not perceived, geography is a dead study. The 
features of the land that the outer eye sees will awaken no suf- 
ficient sympathy in the understanding until the scientific imagi- 
nation has deduced a whole system of geography, filled with 
mental pictures of all kinds of forms in all stages of develop- 
ment, among which the report from the outer eye may find its 
mate. However faithfully mere observation is carried on, the 
impression on the retina might as well be the record ona photo- 
graphic plate, as far as appreciative insight and understanding 
are concerned. Let us therefore strive to complete a deductive 
geographical scheme, even as we strive to complete our deduct- 
ive tidal scheme, until it shall at last be ready to meet not 
only all the actual variety of nature, but all the possible variety 
of nature. Only when such a scheme as this is well advanced is 
the student ready to appreciate the materials presented in the 
laboratory work. The maps and models shown in the first week 


Ve. THE JOURNAL OF GEOLOGY. 


are therefore repeatedly introduced with others in the systematic 
advance of the course; and the student may gauge his progress 
by the increased meaning that these illustrations gain on every 
return. 

Let us next consider the development of a deductive geo- 
graphical scheme, by which external observation is to be supple- 
mented and completed. Let it be understood at the outset that 
to exceed the variety of nature is an extended enterprise, a 
remote and ideal goal, towards which we strive. Let no exces- 
sive flight of theory carry us far from the earth and overcome us 


in mid-air. Let us carefully guard against an unwarranted wan- 


dering of the imagination by frequent conferences with the facts 
of observation, hoping to return, like old Antzus, strengthened 
for new efforts after every touch of Mother Earth. 

The deductive geographical scheme.—I\t is the fundamental 
generalization of elementary geology to note that the lands are 
wasting away under the destructive attack of the weather. The 
hardest rocks decay; their waste creeps and washes down to 
lower and lower levels, never satisfied till it reaches the sea. 
However broad a plateau, however lofty a mountain range, it 
must, if time enough be allowed, be worn down to sea level 
under the weather; and the unceasing beat of the sea on its 
shores must reduce it still lower to a submarine platform. Since 
the remote beginning of geological time there has been time 
enough and plenty to spare to reduce all the lands to such a 
submarine platform; but as high lands still exist, it must be con- 
cluded that they are revived from time to time and from place 
to place by some forces antagonistic to those of subaérial denu- 
dation. In whatever way a new mass is offered to the wasting 
forces, let us call the forces that uplift it constructional forces ; 
and the forms thus given, constructional forms. Let all the 
forces of wasting be called destructional forces; let the sea level 
surface, down to which a sufficiently long attack of the destruc- 
tional forces will reduce any constructional form, be called the 
ultimate baselevel; and let the portion of geological time 
required for the accomplishment of this task be called a geo- 


ere i 


JA IOSICALIL, (GIRO CT AIZ EIS JOM IOS (OOM MI ZTRASION 4 WS 


graphical cycle. Construction, destruction, baselevel and cycle 
are our primary terms. A full understanding of the destruc- 
tional processes requires deliberate study of mineralogy and 
lithology, chemistry and structural geology; a good understand- 
ing of constructional forces and processes has not yet been 
gained, but a review of the advance made towards it carries the 
student through a wide range of geological theories, in which 
physics and mathematics are continually appealed to—perhaps 
sometimes with too great a confidence in the applicability of 
their conclusions concerning an ideal earth to the case of the 
aAchualmeatunn 

If the cycle of destructive development is not interrupted, 
any constructional form will ultimately be reduced to a monoto- 
nous baselevel plain of denudation. This is a broad abstract 
statement. It is simply the first framework of the geographical 
scheme. It is a mere sketch in faint outline, needing all manner 
of finishing before its full meaning can be made out. It must 
be filled in by the gradual addition of details. The first step 
involves the recognition of the systematic sequence of topo- 
graphic forms produced during the accomplishment of the 
destructive work. This should be considered before classifying 
the various kinds of constructional forms on which the destruc- 
tional processes begin their tasks. Whatever constructional form 
exists at the beginning of the cycle, there is a certain general 
succession of features common to nearly all cases of geograph- 
-ical development. The understanding of this succession calls 
for the study of river systems and the general drainage of the 
land under their guidance; because it is so largely under the 
control of these processes that the destructive forces do their 
work. 

Constructional drainage—At the beginning of a cycle, there 
are relatively broad, massive forms, on which the carving of the 
destructive forces has made no mark. The wunconcentrated 
drainage, or wet-weather wash, takes its way down the steepest 
slopes of the constructional surface, until the supplies from either 
side meet obliquely in the trough lines, forming constructional 


74 THE JOORNAL, OF GEOL OG Va 


streams; these unite, forming constructional drainage systems. 
If the trough lines are systematically arranged, as among the 
corrugations of mountain folds, the initial drainage system is 
definitely located; if the trough lines are faintly marked and 
lead irregularly about, as on the nearly level surface of a plateau, 
the drainage is essentially vague and unsystematic. If the gen- 
eral descent of the trough lines is here and there reversed into 
ascent, lakes are accumulated in the basins thus determined ; 
and this is very common. If the descent of the trough lines is 
locally intensified, constructional falls or rapids are developed, 
but this is relatively rare. 

Consequent drainage -—The constructional streams run down 
their troughs, carrying along the waste that is washed into them, 
and trenching channels beneath the initial constructional surface ; 
or filling constructional hollows ; that is, degrading or aggrad- 
ing their course, as the necessities demand. As soon as they 
thus depart from their initial constructional arrangement, they 
may be called consequent streams. It is true that the construc- 
tional phase of a drainage system endures only a moment; 
yet it seems advisable to recognize this phase by employing 
a special name for it, before introducing the term, conse- 
quent, which indicates the much longer phase that next fol- 
lows. At least, I am for the present experimenting on these 
two terms with my classes, and find them of value. As long as 
a stream flows on a line that is essentially the perpetuation of 
its original constructional course, it may be called a consequent 
stream; the trench that it cuts and the valley that is formed 
by the widening of the trench may be included under the name, 
consequent valley. Constructional features are encroached upon 
as the consequent features make their appearance. A con- 
structional lake decreases in size by filling at the inlet and 
cutting down at the outlet; while thus dwindling away, it isa 
consequent lake. A fall or cascade recedes from its initial 
constructional position; but as long as it endures it is a conse- 
quent fall. | 

Subsequent drainage features—As the consequent streams 


EINES CAME Gio OG: eA 7, LING RET SON VEE SLL 75 


deepen their valleys beneath the constructional surface, it often 
happens that they discover structures of unequal hardness. If, 
in passing down stream, a weak structure succeeds a hard struc- 
ture, the valley will be quickly deepened in the former and 
slowly in the latter; a local increase of slope appears and a fall 
or cascade is the result. This is a subsequent fall on a conse- 
quent stream. It endures until the harder structure 1s worn 
down or back so far that it overtakes the deepening of the stream 
bed below the fall. The extinction of falls is accomplished in 
adolescence on large streams and on tilted rocks; but it may 
not be reached until maturity on the smaller streams in regions 
of horizontal strata. 

A further consequence of the discovery of the variable 
resistance of internal structure is the variable rate at which the 
narrow young consequent valley widens into the more mature 
open valley. If the consequent stream crosses a local trans- 
verse belt of hard rocks, the gorge-like form of the valley walls 
may there be retained into the maturity of the region asa whole. 
If it crosses a belt of weak rocks, the consequent valley may 
there widen so greatly as to develop other valleys on either side 
of its path. Thus many a transverse consequent stream, cutting 
its valleys across belts of harder and softer structures, allows the 
development of longitudinal valleys on every belt of weak struc- 
ture that it traverses, while the intermediate belts of harder 
structure stand up as longitudinal dividing ridges. The longi- 
tudinal streams and valleys are then called subsequent branches 
of the transverse consequent streams and valleys. Each 
of the subsequent streams deepens its valley only as 
fast as the down-stream deepening of the consequent valley 
permits. 

It is extremely important to recognize the difference thus 
indicated between consequent and subsequent streams. The first 
control the drainage of a region in its early stages of develop- 
ment. The second are of increasing importance in the secondary 
and later stages of growth, when they share the drainage of the 
region with the surviving consequent streams. Subsequent falls 


76 THE JOURNAL OF GEOLOGY. 


frequently appear on consequent streams, but they are rare on 
subsequent streams. 

It is manifest that the development of subsequent streams 
will progress to the greatest extent in regions of disordered and 
complicated structure, in which the attitude of the rocks is 
varied, and in which contrasts of hardness are well marked. 
Such is the case in mountainous regions. On the other hand, 
regions of horizontal structure have no normal subsequent 
streams. All the branch streams are either perpetuated con- 
stant streams, or else they are developed under accidental con- 
trols, of which no definite account can be given. It is to these 
self-guided streams that McGee applies the term, autogenetic. 

Divides —The constructional divides waste slowly and become 
consequent divides. They are well defined in a region of dis- 
tinct constructional relief; they are vague or practically absent 
on the even surface of young plains, where the drainage areas 
are really undivided. As subsequent streams develop, especially 
in regions of tilted structure, they frequently split a consequent 
divide, and make two subsequent divides between which hes the 
growing subsequent valley. As the subsequent divides are split 
further and further apart, lateral subsequent streams are devel- 
oped down the internal slopes of the subsequent valley ; and 
these are in headwater opposition to the lateral streams on the 
diminishing slopes of the adjacent consequent valleys. During 
changes thus produced in the position of divides, they migrate 
by slow creeping as long as the competing streams are in head- 
water opposition; but if, as sometimes happens, the head of an 
encroaching subsequent stream pushes its divide back until it 
cuts into the side of a consequent stream, then the divide leaps 
around the consequent headwaters above the point of capture, 
and a considerable area that had been tributary to the captured 
stream is suddenly transferred to the capturing stream. 

A limit of these re-arrangements is gradually approached. 
The persistent consequent streams and the successful subsequent 
streams come to an understanding about their drainage areas. 
The divides as wel! as the streams are then maturely adjusted to 


PHVSICAL GEOGRAPHY IN THE UNIVERSITY. hi 


the structures on which they are developed; and thenceforward 
further change is slow. 

Stream profiles—Let us next examine the changes produced 
in the initial profile of the troughs where the first constructional 
streams settled. The irregularities of constructional profile which 
determine lakes and falls are in most cases soon extinguished. 
The profile of a consequent stream may for a time possess 
unequal slopes at its subsequent falls, but it soon attain- 
a tolerably systematic curve of descent, steeper near the head- 
waters, flatter near the mouth. While the young stream has 
abundant fall and rapid current, with moderate load delivered 
from the relatively simple constructional and consequent slopes of 
its basin, it deepens its trench rapidly. But as the profile becomes 
flatter and the current runs slower, and as the area of wasting 
slopes increases by the deepening of the consequent valleys and 
the development of subsequent valleys, a time will soon arrive 
when the carrying power is reduced to equality with the load ; 
and from this time on the deepening of the valley is very much 
slower than before. It is only as the load from the wasting 
slopes decreases in amount that the deepening can goon. Follow- 
ing certain French writers, the profile of the stream when this 
balanced condition is reached has been called the profile of equilib- 
rium. The term is inconveniently long ; but the idea is of essential 
importance. Mr. Gilbert has recently suggested to me that a 
stream in this condition of balance between degrading and 
aggrading might be called a graded stream; and its slope, a 
graded slope. 

It is sometimes said that streams in this condition have 
reached baselevel; but this introduces a confusion of ideas 
that should be avoided. For example: given two constructional 
areas of similar form and altitude, and under equivalent climatic 
conditions ; but let one be made of resistant rocks, and the other 
of weak rocks. The baselevel is the same for both. The 
streams will cut deep into the harder mass, producing strong 
relief before reaching an equilibrium profile ; because its waste is 
shed so slowly that the streams can carry it on a faint slope. 


78 THE JOURNAL OF GEOLOGY. 


They can cut only shallow valleys in the weaker mass, for its 
waste will be shed so rapidly that a steep slope is needed by the 
streams to carry the waste away. The contrast between the two 
areas is strengthened if the region of harder structure has a 
plentiful rainfall, and the region of weaker structure has a light 
rainfall. All of these points of difference are with difficulty 
stated, if the streams are said to have reached baselevel when 
their carrying power is reduced to equality with their load. 

In certain cases, it seems to be possible for a stream to cut 
down its profile to a gentler grade in its early adolescence than 
is suitable to later adolescence and maturity. If we conceive 
that the load offered by the waste from the valley slopes con- 
tinues to increase after the grading of the stream has been reached, 
then the grade must be steepened again by the deposition of 
the excess of load; thus increasing carrying power and decreas- 
ing load, and maintaining an equilibrium. Local examples of 
this relation are often seen in valleys among mountains, where a 
lateral stream is depositing an alluvial fan in the larger valley 
that it enters. The larger valley was deepened before the lateral 
valley had gained a considerable area of wasting slopes ; but as the 
lateral valley grows headwards and discharges an increasing volume 
of waste, it cannot all be carried by the main stream, and hence 
the main valley is clogged up, and its grade is somewhat increased. 

Stages in the cycle of geographic development.—Following the 
terminology of organic growth, it is convenient to speak of the 
successive stages in the geographical cycle as infancy, youth, 
adolescence, maturity, old age, and perhaps second childhood. 
Let us consider particularly the activities of the drainage system 
as determined by the topographic form of a region in its differ- 
ent stages. 

In infancy, the rainfall is slowly concentrated from the broad 
constructional surface ; it is only gradually collected into streams ; 
it is often delayed in lakes. Much of it is lost by evaporation, 
and the ratio of discharge at the river mouth to rainfall over the 
river basin is relatively low. The initial streams simply adopt 
the courses offered to them, without the least consideration or 


PHYSICAL GEOGRAPHY IN THE UNIVERSITY. 79 


foresight regarding the difficulties that these courses may involve 
in the process of valley-trenching. The load that they have to 
carry is relatively light ; being only the waste that creeps and 
washes down the broad constructional slopes, under the guidance 
of the unconcentrated drainage. 

In youth and adolescence, the drainage lines are increased in 
number and greatly improved in their ability to gather and dis- 
charge the rainfall quickly. Numerous little trenches are incised 
in the broad constructional surface, and the distance that the land 
waste washes and creeps under the guidance of unconcentrated 
drainage is much lessened; delay in lakes is decreased; the 
steep lateral slopes of the young consequent valleys furnish an 
increasing amount of load to the streams, although they still as 
a rule have carrying power to spare in their impetuous currents. 
A good beginning is made in the search for the best location of 
subsequent streams. As the subsequent streams are better devel- 
oped in later adolesence, the original broad constructional forms 
are minutely carved, many subsequent divides are established, 
the discharge of rainfall is very prompt, and the load of waste 
that the streams have to carry is notably increased. 

In maturity the relief retains much of the intensity of adoles- 
cence, and adds thereto a great variety of features. The valley 
lines are closely adjusted to the structure of the region, this con- 
dition having been gained by a delicate and thorough process of 
natural selection, in which the most suitable drainage lines sur- 
vive, and the less suitable ones are shortened or extinguished. 
The impetuosity of youth has disappeared ; all the larger streams 
have developed grades on which their ability to do work is nicely 
adjusted to the work that they have to do; the lower courses 
already show signs of age, while the’ upper twig-like branches 
are relatively youthful. The whole drainage system is earnestly 
at work in its task of baseleveling the region, and the forms 
that the region has assumed bear witness to the close search 
made by the streams for every available line of effective work. 

From this time onward, there is a general fading away of 
strength and variety, both of forms and activities. The deepen- 


80 THE JOURNAL OF \GEOLOGY. 


ing of the valleys progresses even slower than the slow wasting 
away of the hill tops; the relief fades; the load offered to the 
streams lessens. The rainfall slowly decreases as a normal con- 
sequence of decrease of altitude ; the ratio of river discharge to 
rainfall decreases ; the small headwater branches shorten and 
dwindle away; the close adjustment of stream to structure is 
more or less lost, especially by the larger rivers, which meander 
and wander somewhat freely over the peneplain of denudation. 
Extreme old age or second childhood is, like first childhood, 
characterized by imperfect work ; activities that were undeveloped 
in the earlier stage having been lost in the later stage. 

All this should be so carefully imagined and so frequently 
reviewed that the orderly sequence of changes may pass easily 
before the mind. The mind should come to be in so close a sym- 
pathy with the progress of the cycle as to forget human measures 
of time and catch instead the rhythm of geographical develop- 
ment; even to the point of almost wishing to hurry to one place 
or another where some change of drainage or of form is immi- 
nent, for fear of failing to be in time to see it in its present stage. 

Shore lines —While the subaérial forces are denuding the sur- 
face of the land, the waves are beating on the shore and reducing 
the land mass to a submarine platform. They begin their work 
on a level line, contouring around the slope of the land mass as 
it is offered to them. The contour is simple if the sea lies on a 
rising sea bottom, evenly spread over with sedimentary deposits ; 
the contour is irregular if the sea lies on a depressed land, more or 
less roughened by previous denudation. The waves of a great 
ocean work rapidly on a leeward shore, especially if it has a steep 
slope and if its rocks are not too hard: but if the descent to 
deeper water is very gradual, the waves may for a time spend 
their force chiefly on the bottom, building off-shore bars with the 
material they gather up, and thus deepening the water outside of 
the bars for a better attack on the land later on. The shore line 
is generally simplified, as the attack advances, but it may fora 
time become more irregular if the waves are strong and the land 
structure is of diverse resistances. Its changes deserve as care- 


IME SINCAUIL, (GIB OGICAIZTEINA JON, Walid, (CINMVATBIR SH ION, 81 


ful an analysis as is given to the forms of the land; but they 
cannot be traced here for lack of space. 

Tlustrations of the deductive scheme.—However much the advance 
of a deductive scheme of study may be aided by reference to con- 
crete illustrations during its progress, its statement should be 
abstract, in order to emphasize the essentially deductive side of the 
study. Itis difficult to follow such a method without artificial aids. 
Hence, in discussing the theory of the tides, a model of certain 
theoretical tidal circles was introduced for the convenience of 
definition and argument. It was found to be an effective aid in 
reaching certain geometrical consequences that follow from the 
rotation of the earth on an axis that is not coincident with the 
axis of the tidal circles. This model was an illustration of the 
same order as the diagrams employed in text-books on geometry. 
In the same way, a series of some thirty rough paper reliefs, con- 
structed several years ago to illustrate a course of lectures to 
teachers under the auspices of the Boston Society of Natural 
History, are introduced to aid in giving clearness to the concep- 
tion of the geographical scheme. They are roughly made; hardly 
better than blackboard diagrams, except in having three dimen- 
sions; yet they certainly serve a good purpose as aids in follow- 
ing deductive statements. Being two or three feet in length and 
yet light enough to handle easily, they are frequently brought 
into the lecture room, although they are used chiefly in the labo- 
ratory, where they can be examined and described deliberately. 
Nearly all the points thus far mentioned are illustrated in one way 
or another by these models; but I can here give account of only 
a few of them. 

While occupied with the first considerations of the cycle and 
its systematic variations of relief, both in intensity and variety, 
use is made of three simple models, which are found to be of 
particular value in fixing the fundamental ideas. The first shows 
a broad upland, traversed by a main river with a few branching 
streams, all in valleys of the canyon type. The form of the 
second is well diversified, there being about as much of lowland 
in its wide open valleys as there is of upland on its well separated 


82 LAE fOUORNAE OF NGHOEOGY. 


hills. The third is a broad lowland for the most part; but low 
hills rise above the general level near the headwaters of the 
streams. The main river has essentially the same course in all 
three models and there is a manifest relation in the position of 
the streams and interstream hills of the series, plainly showing 
genetic relationship. The three models are different forms of 
the same region at certain stages in its cycle of develop- 
ment. Exercises are held in the simple description of these 
forms, and of other forms that might be interpolated in the 
series. It is suggested that the duration of a cycle should be 
divided into a hundred equal parts, and that the stages occupied 
by the three models should be designated by appropriate numbers. 
After some discussion, it is agreed that they may be represented 
_ by five, twenty and forty; thus impressing the idea that maturity 
is reached long before middle life; and that the passage through 
old age is extremely slow compared to the advance from youth 
well into maturity. These exercises are accompanied by others 
in which illustrations of actual geographical forms are presented, 
as willbe explamed: Mater, abut mits ism amp o_taritn chat ane ne 
different character of the two should be clearly kept before the 
mind. 

Complications of the simple scheme.—The difficulty of finding 
examples of actual forms in the various stages of development of 
a single cycle suggests that the departures from the ideal uninter- 
rupted cycle should be examined. These are of two kinds, which 
I am accustomed to call accidents and interruptions. Such depar- 
tures as do not involve a change in the attitude of a land mass 
with respect to its baselevel may be classed under the first head- 
ing as accidents; those which do involve a change with respect 
to baselevel will fall under the second heading of interrup- 
tions. 

The most important accidents are climatic and volcanic.  Cli- 
matic accidents include changes from humid to arid, and from 
cooler to warmer conditions, independent of the normal climatic 
change due to loss of relief from youth to old age. A study of 
such a region as the Great Salt Lake basin, or as the glaciated 


IMEDGSUGAIL, (GR OGIR ASIEN SOM, Tidal, (GINGIVITIS SII 83 


district of northeastern America assures us that these accidents 
may succeed each other rapidly; very rapidly compared to the 
rate of normal climatic change dependent on loss of relief from 
a co. 3tructional beginning to a destructional end. Volcanic acci- 
dent: include the building of cones and the outpouring of lava 
flows. Both the glacial and the volcanic accidents may occur at 
any st..xe of a cycle. They both in a way involve constructional 
processes; both may be regarded as furnishing examples of new 
constructional forms; but when looked at with respect to the 
surface on which these accidents are imposed, and with respect 
to the relatively brief endurance of the effects of the accidents, 
they are seen in their relatively subordinate character. When 
sheets of drift are heavily spread over a country of low relief, 
or when heavy lava floods cover and bury some antecedent topog- 
raphy, the accidents assume such proportions that they may be 
considered as revolutions, after which a new start is made in the 
processes of denudation. 

A cycle is interrupted when the land mass rises or sinks, or 
when it is warped, twisted, or broken. Like accidents, inter- 
ruptions may happen at any stage of development. It is then 
convenient to say that the destructional form attained in the 
first incomplete cycle shall be called the constructional form of 
the new cycle, into which the region enters, more or less tilted 
or deformed from its former shape. Assuming for the moment 
that the constructional process is so rapid that its duration may 
be neglected, it follows that in cases of simple vertical movement, 
up or down, the rivers and streams at once proceed to adapt their 
activities to the new conditions. They are shortened and be- 
trunked, if the interruption is a depression; they are revived and 
extended if the interruption is an elevation. These two special 
conditions are illustrated by paper models. One model exhibits 
a rolling country, into which a branching bay enters; a stream 
descending into the head of every branch of the bay. No flats 
occur at the head of the bays; no cliffs are seen on the head- 
lands. Hence it is said, that on reaching maturity this country 
was depressed, and that the depression occurred very recently. 


84 THE JOURNAL OF GEOLOGY. 


The numerical expression of this example would be 20, —, 0: 
the minus sign not indicating subtraction, but merely signifying 
depression; and the zero indicating that no advance has been 
yet made in the new cyle. Another model exhibits a broad, 
gently undulating upland, traversed by a very narrow canyon. 
This is interpreted to signify that an elevation occurred in the 
old age of the region, and that since then the streams have simply 
entered a new youth, incising young valleys in the uplifted 
peneplain. The formula of this example would be 60, +, 3. 
Examples involving deformation of a land surface, and the 
accompanying possibility of antecedent streams, are more 
complicated, and cannot be here introduced. 

It is convenient to use the term, episode, for slight inter- 
ruptions, so as to express their relative unimportance. I have 
also attempted the use of the term, chapter, for an unfinished 
cycle; but in talking with students this specialization of terms 
hardly seems necessary. Any region whose surface has been 
developed, partly with relation to one baselevel, and partly in 
relation to another; that is, any form whose development has 
involved two or more incomplete cycles, is said to have a com- 
posite topography. Many examples of such forms are encoun- 
tered. 

Special features of second or later cycles—It is interesting 
to notice that, in certain cases, the adolescent stages of a sec- 
ond or later cycle, following the elevation of a region well 
advanced in a previous cycle, present features that did not 
characterize its first adolescence. One case of this kind is seen 
in meandering river gorges. Young rivers in their first cycle 
may cut crooked gorges, but they then follow consequent 
courses, and these cannot manifest the close relation between 
volume and radius of curvature that is seen in true meanders. 
This relation is found only in oldish rivers, which develop sys- 
tematic meanders on their own flood plains. But if the region 
on which these rivers flow is introduced into a new cycle by 
uniform elevation, the rivers may cut down their meandering 
channels and produce meandering gorges. The Osage in Mis- 


IIE SGSICAUL, (GAR OGIRAILIEIE JUN, Sa R, (GUN MASI GST ING. 85 


souri,’ and the north branch of the Susquehanna in Pennsylvania ; 
the Seine in northwestern France, and the Moselle in western 
Germany, may be cited in illustration of this kind of occurrence. 

Another case in which a second adolescence is unlike the 
first is found in regions of tilted structure, where the strata are 
of diverse resistance, thus giving good opportunity for the devel- 
opment of subsequent streams. In the beginning of the first 
cycle there are no subsequent streams. All the drainage is con- 
structional (antecedent streams not being now considered). In 
adolescence, the drainage is chiefly consequent, although subse- 
quent side streams are then beginning to bud forth from the 
consequent streams. In past-mature stages, the subsequent 
streams may have acquired a considerable part of the drainage 
area. Now, if a region of this kind, with consequent and subse- 
quent drainage, is bodily elevated, all the streams are revived; 
they all cut down new trenches toward the new baselevel. 
But in this case the revived subsequent streams begin the new 
work at the same time as the revived consequent streams, and 
they will go on rapidly in acquiring still more drainage area. 
Therefore, in the adolescence or maturity of the second cycle, 
the drainage area acquired by the subsequent streams will be 
proportionately large; much larger than at the same stage of the 
first cycle. Much faith may be placed inthis deduction. If the 
drainage of an adolescent region is largely subsequent, and but 
little consequent, the region may be regarded as almost certainly 
in a second cycle of development, after a first cycle of well- 
advanced age. 

Illustrative material—One of the greatest difficulties in the 
way of teaching physical geography arises from the failure of 
the student to know what the teacher is talking about. The 
teacher may have traveled and observed extensively; a large 
variety of geographical forms are in his memory, ready to be 
summoned by name when picturing the stages of the deductive 

Tt has been suggested to me by Mr. Arthur Winslow that the Osage has increased 


its original meanders in cutting down its gorge. The other rivers here mentioned 
seem to have done the same thing. 


86 TELE J OWKINATL (OLR (CIE OMLOE V7 


scheme; but no amount of description suffices to place these 
mental pictures before the class. The best means of overcoming 
this difficulty is found in the use of the projecting lantern; and 
now that the electric light may be used in projecting slides on 
the screen, and the room kept light enough for the class to take 
notes while the pictures are exhibited and explained, the only 
thing left to be desired is a good series of views, carefully 
selected to present typical examples of land forms in various 
stages of more or less complicated development. These views 
are not intended primarily to furnish localized examples of geo- — 
graphical forms; although, of course, they have much value in 
that direction. Their greater value comes from the vividness of 
the conceptions by which the different kinds of forms and differ- 
ent stages of development of the deductive scheme are held in 
~the mind. The collection of slides that I now use includes a 
large variety of views; although very useful, it is still imperfect. 
It should be extended by the addition of many views taken 
expressly to meet its needs; for the photographs and slides com- 
monly to be had of dealers are as a rule taken with anything but 
geographical intention. As an indication of the character of 
illustrations used in a single lecture, 1 may mention the follow- 
ing examples, and add an outline of the comments made on 
them. 

When the general idea of a geographical cycle has been pre- 
sented, including the constructional forms with which it begins, 
and an outline of the destructional forms by which its develop- 
ment is characterized, the next lecture may be devoted almost 
entirely to illustrations. First, a few slides to show various. 
constructional forms. Muir’s Butte, a young volcanic cone in 
California, introduces a series; it is practically unworn. Its 
growth was so rapid and so recent that no significant advance in 
its denudation has yet been accomplished. Mt. St. Elias comes 
second; as described by Russell, it is a constructional form 
slightly altered; an essentially young mountain mass. The 
considerable time required for accomplishment of so great a 
constructional work may have been enough for the slight dissec- 


JEVAI VE SICAL, (CAR OG AV AERC ION, IEG 2 (UING VARS INNA 87 


tion already seen on its surface. While the building of a vol- 
canic cone is spasmodic, almost instantaneous, the uplift of a 
great mountain is rather slow; its uplift is brief only when com- 
pared to the duration of the destructive cycle on which it thereby 
enters. When first describing the cycle, it was implied that the 
destructive forces make no beginning until the constructional 
forces have completed their work. The view of St. Elias cor- 
rects that false idea. Several plains follow; all dead level; all 
ending in even sky lines. The Llano Estacado of Texas, the 
lava deserts of southern Idaho, the littoral plain of southern 
New Jersey, the lacustrine plain of the Red River of the North. 
The areas included in these views show no signs whatever of 
destructive processes; the surfaces are essentially as flat as when 
they were born. A pair of drumlins in Boston harbor, and a glacial 
sand-plain in Newtonville, Mass., as represented in a model by 
Mr. Gulliver, introduce examples of peculiar constructional 
forms; and as the more intelligent members of the class soon 
point out, these might be as fairly included under a considera- 
tion of destructional processes as of constructional processes ; 
for they really belong among the ‘‘forms taken by the waste of 


d 


the land on its way to the sea,” under certain special conditions, 
and they will be reviewed in a later chapter of the course 
under that heading. The drumlins and the sand-plain may also 
be regarded merely as evidence of a glacial accident during the 
denudation of the New England plateau. 

Passing next to illustrations of young destructional forms, 
Mt. Shasta is exhibited, with great gulleys worn down its flanks. 
It is at once pointed out that these gulleys follow lines of con- 
structional slope; that they began as the paths of constructional 
streams, defined by some accidental irregularity in the form of 
the volcanic cone; and that they are now slightly advanced in 
their consequent growth. The Mancos canyon in Colorado illus- 
trates the beginning of the dissection of a plateau; the conse- 
quent stream having here cut down a steep-sided consequent 
valley, but apparently not having yet graded its slope. A 


tSee this Journal, Vol. I., p. 801. 


88 Eh [OUTINATE, (OP CHROIMOG INE 


stream in Florida, hardly incised in the low coastal plain, illus- 
trates the faint relief permitted in surfaces that stand but little 
above their baselevel. The Colorado, in its canyon, is another 
example of an early stage of development, but it possesses an 
extreme intensity of relief because of the great altitude of its 
plateau ; not an old valley, but a precocious young valley; not 
a vast work, except in our inappropriate human measures, but 
the good beginning of a vast work. The Elbe above Dresden 
offers illustration of a later stage than the three preceding; it 
has the beginnings of a flood plain, now on one side, now on the 
other side of the river; from which it is inferred that the deep- 
ening of the valley has practically ceased, that the river is 
graded, and that the slower process of valley widening is now 
the determining cause of topographic change. 

Views in the Jura mountains would serve as examples of 
adolescent forms, combining an interesting measure .of conse- 
quent and subsequent features ; but I have not yet succeeded in 
finding any satisfactory photographs of this region. Features of 
maturity, more or less advanced, are found in the retreating 
escarpments of the middle Ohio valley* or of the central denuded 
region of Texas ; and again in the minutely carved ranges of the 
central Alps. For yet older stages, it is difficult to find exam- 
ples still in the cycle in which their old age was reached ; but 
the plain of the middle Wisconsin river and the plateau of the 
middle Rhine are ideally satisfactory illustrations of baseleveled 
surfaces, one being an old plateau, and the other an old moun- 
tain region ; although both have lately been brought into a new 
cycle by elevation, allowing their rivers to cut narrow trenches 
beneath their even surfaces. By selecting views in which only 
the plain surface is seen, these examples make appropriate clos- 
ing members of the series here described. Ata later time, when 
the complications of the cycle are in discussion, other views 
showing the dells of Wisconsin and the gorge of the Rhine may 
be presented, thus giving a new meaning to old examples. 


tNot the slopes of the young trench by which the Ohio now cuts across the Cincin- 
nati plain, but the escarpment enclosing the plain many miles back from the trench. 


IEE NASIC AE, (HA OCIS AVAIANE JEN IS EUD, (CIN WIBTRASIINE, 39 


Systematic examination of facts—While the deductive geo- 
graphical scheme is thus gradually extended, while its various 
elements are illustrated more or less completely by black- 
board diagrams, diagrammatic models, and lantern slides, 
an acquaintance with the facts of the subjects is gained at the 
same time chiefly through the laboratory work of the course. 
This is for the most part devoted to the examination of maps 
and many other illustrations of actual geographical forms, intro- 
duced systematically to represent the kinds of construction and 
the stages of development that may be compared with similar 
kinds wandistaaesmingache “deductive. schemes) I resandaitjeas 
essential that the two sides of the work should advance together. 
The theoretical considerations of the deductive scheme and the 
inductive observation, description and generalization of the facts 
of nature continually react on each other to mutual advantage. 
They call different mental faculties into exercise. Neither one 
can be developed alone to the best advantage. It is true that 
“the consideration of the two sides of the work at the same.time 
leads to mental confusion on the part of untrained or careless 
students, but this does not seem to me unfortunate. It is, to be 
sure, rather disappointing for a young fellow to find in the mid- 
dle of the course that his neglect of its beginning has left him 
hopelessly behind his better prepared or more persevering com- 
rades ; but it is much more disappointing to see how often col- 
legiate instruction is degraded by allowing it to fall to the reach 
of students who do not know how or who do not care to know 
how to follow its proper quality. In work of the kind that I am 
describing, mental confusion soon overtakes those who are 
poorly trained for mental effort. I do not find that it makes 
much difference what subjects a student has been trained in, pro- 
vided that he is well trained. 

Laboratory work is an important element in the study, because 
there is otherwise no opportunity for deliberate and close obser- 
vation of geographical facts. Even if shown inthe lectures, they 
cannot be clearly seen, and there is no time then for close study. 
No text book or atlas contains illustrations in sufficient variety 


gO THE JOURNAL OF GEOLOGY: 


for collegiate work. But in the laboratory, numerous maps, 
views, or models may be exposed on walls, racks, or tables, 
remaining for a week together, and thus giving abundant 
time for deliberate examination. From week to week a change 
may be made in the materials, the group for each week corres- 
ponding to the group of problems then in hand. Many of the 
illustrations shown in the first week are repeatedly brought forth 
again later in the course, always gaining new meaning as sharper 
outsight and insight are directed to them. Many facts of inter- 
est concerning population and occupations may be brought for- 
ward in this connection ; but it is important that the geographical 
facts should first be clearly apprehended. 

In the reports that are made on this laboratory work, the 
students first describe the facts that they have observed, in terms 
that have no suggestion of explanation. They should not say 
that a certain region is a baselevelled surface; but that it is a 
lowland of faint relief. They should not at first speak of old 
rivers revived into a second youth; but they may say that the 
rivers of a certain region run in deep, narrow valleys below an 
upland of generally uniform altitude, above which occasional 
isolated hills rise to greater elevations. This I regard as 
extremely important, in order to ensure a careful. observation of 
the facts in discussion ; for until the facts are clearly perceived 
they cannot be precisely explained. It is unsafe at first even to 
speak of the flat region at the mouth of a river asa delta. This 
term not only denotes the form of the surface but connotes an 
explanation; and in the earlier weeks of the study it is by no 
means sure that the observer fully perceives all the facts of form 
that are denoted by the term, or that he fully appreciates all the 
features of the process that are connoted in its explanation. The 
outbranching of the distributaries near the river mouth as con- 
trasted with the inbranching of the tributaries (or contributaries, 
as they might be called), further up stream ; and the faintly con- 
vex form of the delta surface as contrasted with the concave 
form of the upper valley may not be clearly observed, unless they 
are concisely formulated in a description. The essentially bal- 


PH VSIGALAGHO GTA PL VAIN) | TLE SOUND VE TST DY. gi 


anced relations of carrying power and load involved in the 
explanation of the growth of delta may not be perceived unless 
it is carefully discussed in making out the scheme of river devel- 
opment. There can be no thoroughness of work where obser- 
vation and explanation are slurred over or confused. After 
observation and description are well advanced, explanatory terms 
may be introduced ; it then being seen that such terms imply a 
pairing off of observed facts with the appropriate members of 
the deductive scheme. This mental process must become per- 
fectly conscious ; its several steps must be recognized in their 
proper relations. No strong grasp of the subject can be gained 
until the student sees clearly where every part of the work stands 
in relation to the whole. 

Topographical maps published by the U.S. governmental bureaus.— 
It is difficult to secure a full series of facts for laboratory study. 
My plan at present is to select maps from our own surveys and 
from the surveys of foreign countries, with little regard to local- 
ity, but with much regard to geographical features. The charts 
of our coast survey offer admirable illustrations of litoral forms. 
For example, the sand-bar cusps of Capes Hatteras, Fear, and 
Lookout, and their off-shore shoals, all formed between back-set 
eddy currents, rotating betwixt the Gulf stream and coast ; or the 
blunted Canaveral cusp on the Florida coast, and its southward 
migration from a former position ; or the fjords and islands of 
Maine; the sounds of North Carolina; the delta of the Missis- 
sippi, a geographical gem.* The maps of the Mississippi River 
Commission offer remarkable illustrations of the behavior of a 
large river on its alluvial plain. Its meanders, its cut-offs, and 
its ox-bow lakes are shown to perfection. The eight-sheet map 
of the alluvial basin of the Mississippi, prepared by this commis- 
sion, can be had for a merely nominal charge; it exhibits the 
lower part of the great river in an admirable manner. It tells 
the curious story of streams that descend from the eastern bluffs, 


‘It is not generally enough known that the illustrated catalogue of the Coast Sur- 
vey Charts may be had free of charge on application by responsible persons to the 
Superintendent of the Survey in Washington. 


Q2 THE YOORNAL VOTAGHOLO GN: 


but are unable to ascend across the flood plain to the Mississippi ; 
they therefore unite and form the Yazoo river which runs south- 
ward along the eastern margin of the flood plain, near the foot 
of the bluffs. It would have to pursue an independent course all 
the way to the Gulf, were it not that the Mississippi comes 
swinging across the plain, and picks up the Yazoo at Vicksburg. 

But it is the topographical sheets of the U. S. Geological 
Survey that afford the greatest variety of illustrative material 
for this country; and it is not too much to say that the facts 
they present create a revolution in the student’s knowledge of 
his home geography. We may well wish that they were more 
“accurate, but, with all their imperfections, they present a great 
body of new information. Under the family of plains there are 
examples of low litoral plains in New Jersey and Florida, the 
latter being so young that the constructional lakes are not yet 
drained. The moderate advance in denudation of an upland— 
itself an old lowland of denudation—is seen in the meandering 
gorge of the Osage in central Missouri; the relatively uncut 
plateaus of Arizona are seen alongside of the beginning of their 
denudation in the grand canyon of the Colorado. Maturely dis- 
sected plateaus are found in West Virginia and eastern Kentucky ; 
in northern Alabama and northern Arkansas ; but the first two are 
of minute topographic texture; the second two are of coarser 
forms. Outliers of past-mature plateaus are shown on several 
sheets in central Texas. All manner of other illustrations are 
found in the same series of maps. The thoroughly adjusted 
streams of the Pennsylvania Appalachians; the superimposed 
streams of northern New Jersey ; the Illinois river, the type of a 
medium-sized river in the abandoned channel of a large river ; 
this being the only well-mapped example of the kind in this 
country ; the warped intermontane valleys Of Mlombama yi Craver: 
Lake in northern California; glacial lakes in Massachusetts ; 
flood plains slanting away from their river in Louisiana ; fiords 
in Connecticut ; moraines in Rhode Island ; drumlins in Wiscon- 
sin; trap ridges in New Jersey ; revived old mountains in North 
Carolina; half-buried mountains in Utah and Nevada. Every 


ESCA GEOG TRA PLIY LN, LETS OI LGV LER STE A 93 


new package of these maps brings some new illustration, which 
is put in use as soon as opportunity allows. One of the latest is 
a peculiar case in Southern California : a number of small rivers 
are here seen running down from the Coast range to the shore of 
the Pacific ; but their mouths are all shut up by sand-bars in the 
most summary manner! A curious trick for a Pacific ocean to 
play on some trifling little streams that one would think were 
beneath its notice. 

These maps are simply indispensable. They call forth much 
interest from the class. At first hardly translatable into words, 
their meaning grows plainer and plainer, until at the close of 
the course they are as suggestive as they were uncommunicative 
at the beginning. 

Foreign topographical maps—Not less valuable and far more 
accurate than our own topographical sheets are those of various 
foreign topographical surveys. Unfortunately the relief in most 
of these is expressed by hachures ; altitudes being given only for 
occasional points, or by widely separated contour lines ; but the 
general expression of the surface is certainly admirably rendered 
in many of the surveys. The older maps are generally too 
heavily burdened with hachures ; but the more modern surveys 
ake teh aiuisticallly vexecuted.) It has\ibcen mys practice: tox 
several years past to select certain groups of sheets from the sets 
of foreign topographical maps in our college library, and order 
extra copies of these groups, mount them on cloth and rollers, 
and thus prepare them for the most convenient use in the labora- 
tory. Both the library and laboratory collections of this kind 
are increasing year by year, and I shall soon prepare a special 
account of the grouped sheets, in the hope that others may per- 
ceive their great value and introduce them as teaching materials 
as far as possible. Without specifying all that have been thus 
far secured, I may briefly mention some of the more interesting 
examples. 

From the Army Staff map of France (1: 80,000) there is a 
group of sheets showing the level plain of the Landes, with its 
exceptionally straight shore line and its wide belt of litoral sand 


94 THE JOURNAL OF GEOLOGY. 


dunes; the beautiful group of radial rivers, flowing down the 
slopes of a great alluvial fan that has been formed where several 
large rivers emerge from the Pyrenees, this being one of the best 
examples of a simple consequent river-grouping that I have 
found; the plateau of the lower Seine, an old upland of denuda- 
tion, with an excellent meandering river gorge of moderate depth 
cut through it, together with certain interesting features of young 
branching river valleys, and of rivers that have been shortened 
by the encroachments of the sea in cutting away the land. To 
these I intend shortly to add groups of sheets showing the dis- 
sected escarpment west of Rheims and Chalons, with its beauti- 
fully adjusted rivers, the delta of the Rhone, and the fiorded 
coast of Brittany. 

From the Ordnance Survey of Great Britain (1 : 63,360) one 
set of sheets includes the central Highlands of Scotland, with 
the Great Glen and Glen Roy ; two other sets include the fiords 
and islands of the southwestern and the northwestern coasts. 
These three sets agree in showing an old peneplain of denudation, 
then elevated and maturely dissected, and now somewhat depres- 
sed, with cliffs nipped on its land heads and deltas laid in its bay 
heads. Their formula, according to the plan already suggested, 
would be 75, + 25, — 2. A glacial accident of late date is 
recorded by the upland tarns and the valley lakes. A group of 
sheets for southwestern Ireland exhibits bold mountain ranges 
running directly into the sea, forming a strongly serrated coast. 
The English sheets are of older date and are not of particularly 
good expression, and for this reason I have not yet ordered any 
of them ; although the ragged escarpment of the chalk and of 
the odlite trending northeast on either side of Oxford should be 
represented ; and the Weald offers excellent illustration of well 
adjusted consequent and subsequent rivers on an unroofed dome 
of Cretaceous strata. 

The map of the German Empire (1 : 100,000) supplies many 
examples of striking features. The plateau of the Middle Rhine 
has already been mentioned as a subject for lantern slides ; it is 
represented in two map-groups, one of which shows the tranverse 


EIS CAVENG 2 OGICA LIN LIN LATED, GINA STALE 95 


gorge of the Rhine; the other includes the meandering gorge 
of the Moselle, with a perfect showing of its abandoned cut-offs 
among the hills. The flood plain of the Rhine about Mannheim 
exhibits the former meanders and the present controlled course 
of the river, foreshadowing the future control of the Mississippi ; 
the morainic country of Prussia isa medley of hills and hollows ; 
the Vistula turns sharply at its Bromberg elbow from the valley 
that it once followed, but which it now abandons to the little 
Netze ; long curving sand bars form the two enclosed bays of 
eastern Prussia (the Frische and Kurische Haffe). From Nor- 
way (1: 100,000), the district of the Christiania fiord is already 
received in ten sheets of most delicate execution ; the greater 
fiords of the western coast will be ordered as soon as fully pub- 
lished. From Russia (1 : 400,000), the lakes of Finland, and of 
the lower Danube. From Austria, a portion of the flood plain of 
the Danube, and a strip of the fiorded coast of the northern 
Adriatic. Thisis only a beginning of what I hope the collection 
may be in a few years. 

I cannot speak too highly of the educative quality of these 
grouped sheets. It is, inthe first place, a good thing for students 
to inspect, as closely as they may in laboratory work of this 
kind, the very best products of geographical art. Their ideals 
are thus raised above the commonplace level. Whatever they 
afterwards see will be compared with a high standard. A feeling 
of dissatisfaction will arise regarding the very inferior maps of 
their home states, to which they have been inured, and from this 
a demand will grow for the continuation and improvement of the 
mapping of our country that is now going on. In the second 
place, the facts of the subject are placed before the student 
-so Closely that he cannot fail to be impressed at once with their 
real features; and these he will find so numerous and so varied 
that he will perceive the need of serious study for their appre- 
hension. No verbal descriptions from the teacher suffice to 
replace the portrayal of geographical relief on good maps. 

Classification of constructional forms.—It is only after the 
deductive scheme is well advanced, and after many examples of 


96 THE JOURNAL OF GEOLOGY. 


facts have been correlated with it, that I introduce a classifica- 
tion of constructional forms. Some such classification is essen- 
tial, but it is difficult to establish satisfactorily, because of the 
endless variety of structures found in nature. At present in the 
elementary course I recognize only plains and plateaus of hori- 
zontal strata ; mountains of disordered strata, with many minor 
subdivisions ; and in a subordinate way, volcanic cones and flows, 
and glacial hills and moraines. Like the more difficult orders of 
plants in an elementary course on Botany, mountains must be 
treated briefly in an elementary course on Physical Geography, 
and their fuller treatment left for more advanced study. After 
the various kinds of constructional forms are treated, it is advis- 
able to review the features of rivers, with their divides, lakes, water- 
falls, flood plains, and deltas; and in this connection a week or 
two may be given to the forms assumed by the waste of the 
land on the way to the sea. The distribution of different kinds 
of forms should be briefly given with their classification. 


When thus developed, Physical Geography may worthily 
claim the dignity of a University study. Its subject matter ts 
of importance in itself, as well as in its relations to geology, 
zoology and botany, or to history and economics. Its methods 
are of value in training various mental faculties: observation, 
description, generalization ; imagination, comparison, discrim- 
ination ; these are all cultivated to a high degree in the student 
who successfully utilizes the opportunities of the course. 

Two other aspects of the subject may be briefly considered. 

Areal geography.—The study of the fauna and flora of a region 
or of a continent requires the examination of all of its animals 
and plants according to some acceptable scheme of classification. 
The study of the areal geology of a region involves the exami- 
nation of its formations in their order of local occurrence, but 
also with regard to the general, world-wide scheme of geological 
classification. In the same way, the study of the areal geog- 
raphy of a country or of the world calls for the recognition of the 
parts that compose the whole, of their location and area, and of 


PHYSICAL GEOGRAPHY IN THE UNIVERSITY. Q7 


their classification according to some rational and comprehensive 
scheme. Geographical descriptions now current are very defect- 
ive in the latter respect. They are for the most part empirical ; 
and like empirical descriptions generally, they are short-sighted 
or blind. One of the difficulties in the way of improvement lies 
in the need of geological data ; for without sufficient information 
as to geological structure and history, no satisfactory geo- 
graphical description can be written. It might from this be 
inferred that, where the geology of a region had been deciphered, 
the geologist could give an account of its geography as well ; but 
judging by the existing condition of these two branches of earth- 
science, such is not the case. A great part of the facts that are 
essential to the geologist are not needed by the geographer. 
Many considerations that are important to the geographer receive 
little attention from the geologist. Each is fully occupied in his 
own special field. Advance in the study of areal geography, 
therefore, calls first for proficiency in systematic geography, next 
for a knowledge of general geology and of the local geology 
of the region to be studied, and finally a special geographical 
examination of the region. With such a preparation, a course 
might be planned on the physical geography of Europe, or of 
the United States; and either course might occupy half a year 
or a year very profitably. Most of the examples already intro- 
duced in the elementary systematic course would here be found 
again, and many others with them, until the whole area of the 
country was covered. 

Geographical investigation by the state surveys.—The chief diffi- 
culty in planning such a course is the scarcity of good geo- 
graphical material ; but, on the other hand, one of the chief inter- 
ests in geography comes from the opportunities that it offers for 
new investigations. When we inquire into the generally impov- 
erished condition of geographical teaching in our schools, the 
main difficulty is undoubtedly to be found in the deficiencyfof 
good geographical literature, both in text books and in collateral 
reading, ready for teachers’ use. Consider the case of Ohio, for 
example. Where shall the inquiring teacher in that state turn 


98 WEi3, OWINAUL OP (EIROLOGE NY, 


for a rational account of its physical features, presented in the 
light of modern research? No such account exists. The 
Empire state is no better off; perhaps notso well. In both these 
states, as in all others, local physical geography is a most 
attractive field. It is through this field that the scholars should 
be led out to see the rest of the world; yet the teachers have 
not sufficient means of presenting the facts of the subject to their 
classes. To most persons the facts of our home geography are 
really unknown. <A few investigators, mostly members of geo- 
logical surveys, possess a more or less intimate personal knowl- 
edge of their states; but it is too often stored only in their 
minds, and there remains inaccessible to others, unless by per- 
sonal interview. It is indeed rather curious that the state geo- 
logical surveys have not before now undertaken systematic 
-geographical descriptions of their areas; much more extended 
than the too brief chapters with which the serious geological 
descriptions are often prefaced. The geographical descriptions 
will never be well done until they are made the work of well 
trained specialists, whose first attention is directed to this sub- 
ject. The stratigrapher, the petrographer, and the paleontolo- 
gist are too fully occupied with their own studies to undertake 
geographical studies at the same time, even if they had the proper 
preparation for doing so. The effort at double investigation is 
seldom successful. In the present stage of study it is more 
economical to give each investigator a single problem over a 
whole state, than to assign to one person all the problems of a 
limited district. 

It does not seem improbable that inthe near future a number 
of our state surveys may undertake studies in this neglected field, 
and thus furnish to a new class of readers a fund of material for 
which they have long been waiting. The teachers of a state will 
welcome geographical chapters in the annual reports of their 
survey on the physical features of their home district. The 
surveys will certainly welcome the new support and interest that 
will thus be awakened in their work. The geographical chapters 
may for a time have to be prefaced with introductions, after the 


PEM SICAL NGLOGRA PI, TIN THEE, (OINTVLER ST ION. 99 


style of those geological synopses by which many of our state 
reports are opened. The accounts of a certain group of geo- 
graphical features should always involve the comparison of local 
examples with those from other regions, much as the paleontolo- 
gist or the petrographer makes his comparisons of home and 
foreign examples of fossils or rocks. The chapters must be 
written in simple style, for many teachers must use them as ref- 
erence books. They must be well illustrated, for most teachers 
will have no other pictures of their home district, however well 
they may be supplied with views of foreign countries. They 
must, above all, be prepared in accordance with a well considered 
geographical system. The chapters should not be so long as to 
fatigue or repel, but rather so short as to awaken an appetite for 
more reading of the same kind. They should be published not 
only in the usual annual reports, but also as separate pamphlets 
‘for distribution to all schools through the state superintendent 
of public instruction. Studies of this kind promise to offer 
most attractive subjects for geographical investigation for many 
years to come. 

There is another and quite different direction in which good 
work should be done by the trained geographer. That is in the 
preparation of maps and illustrations for school books. It is 
manifest enough in examining the maps now in use that they 
have been drawn by draftsmen, not by geographers. Their lines 
show no sufficient knowledge of the facts that should be repre- 
sented. They are simply copies of other maps, with no sufficient 
expression of meaning. The relief of the land is generally so 
poorly represented on school maps that no criticism of its execu- 
tion will make it right; it must be done over again. The out- 
lines of coasts and the courses of rivers are often merely carica- 
tures of the facts. The meaningless irregular curves of Cape 
Cod and of the Carolina coast offer amusing illustrations of this 
in many a school geography. The student of geography, who 
prepares for his work by a good foundation in geology, who car- 
ries his geographical studies to the point of original investiga- 
tion in different parts of the country, and who has a happy 


100 THE JOURNAL OF GEOLOGY. 


facility in drawing and, if possible in modeling also, may rest 
assured of a busy future after his apprenticeship. His services 
will be in demand by more than one publisher as soon as his 


work is known. 


W. M. Davis. 


HARVARD UNIVERSITY, December, 1893. 


TE DILROR IAS 


Ir has been announced that the Board of Directors of the 
Geological Survey of Missouri have decided to publish only three 
more reports, viz.: those on paleontology, on clays, and on lead 
and zinc; and ‘‘to abandon other work on reports on hand, whether 
nearly completed or not,’ as well as to discontinue the survey 
akteGn Une I Looe 

We hope that this report is entirely erroneous. If it is true, 
however, those who have followed the history of the Geological 
Survey of Missouri will hear the news with deep regret. The first 
appropriation for the present survey was made by the legislature 
in 1889, and in the fall of that year Mr. Arthur Winslow was 
appointed State Geologist. Since that time the work of the sur- 
vey has been rapidly and intelligently developed, and a number 
of valuable reports have been issued. Though these reports 
contain a great amount of information, there is vastly more yet 
which should, and would, if unhindered, appear in later volumes. 
In the work of a state geological survey the different subjects 
discussed are not worked up entirely independently of each other, 
but in the collection of data in the field on one subject, the geol- 
ogist collects incidentally many facts relating to other subjects 
which he expects to treat of at a subsequent time. As a result 
of this, the amount of information on all points of scientific or 
economic importance is steadily increasing in the office of the 
state geological survey ; and every report that is published means 
not only that the subject to which it relates has been thoroughly 
investigated, but also that many facts relating to other matters of 
general interest have been collected, and will, at some future 
time, be supplemented by additional facts and form the basis of 
other reports. 7 

. When a survey has completed its work on most subjects and 


has but little left to publish, its discontinuance, though it may be 
IOI 


102 RHE VfOOKIN ALOR MGGT OL OGVA 


premature, is not so injurious as when a survey like that of Mis- 
souri, which has just reached maturity, and is in its most active 
and useful stage, is suddenly discontinued. Great quantities of 
unpublished information relating to many different subjects and 
in various degrees of preparation are absolutely lost to the state, 
for much of such information is necessarily too incomplete to be 
published without further field work. It has been collected, how- 
ever, at very considerable expense, and much of it, with a little 
more time, would be ready to be published and would become 
of lasting benefit to the state. 

By the premature abolishment of a survey, therefore, the 
state loses not only the money actually invested in these unfin- 
ished reports, but it loses the reports themselves, which are on 
subjects in which almost every citizen in the state is either 
directly or indirectly interested. More than this, in dispensing 
with a state geologist and his staff, who for years have been 
actively and intelligently fulfilling the functions of their offices, 
the state also loses the benefit of the vast amount of general 
experience in the region that they have acquired during their 
investigations. If the survey is ever reorganized, the new 
officials must not only acquire the same experience over again, 
at the expense of the state, but they must also collect again the 
facts lost on the discontinuance of the preceding survey. 

The history of many states shows that several times they 
have organized surveys and then abolished them before the work 
was completed, or even fairly started; and that perhaps years 
later they have organized new surveys. In some cases this pro- 
cedure has been repeated so many times that the advantages 
gained have cost the state immensely more than they would 
have done if the first survey had been continued to completion. 
Missouri itself has had several such experiences, and the friends 
of the state had hoped, when the present survey was inaugurated, 
that it would be continued until all its great geological and min- 
ing resources had been fully investigated. 

In a number of cases, in times of financial depression, state 
legislatures have been obliged to curtail their expenditures ; and 


DTT ORLATES.. 103 


though, as has been shown, it is very unwise to decrease the 
requisite appropriation for a geological survey, yet if, under such 
circumstances, it is necessary to do so, the office of state geolo- 
gist and its incumbent, if he is efficient, should nevertheless be 
retained, for he possesses facts on unfinished work and a general 
experience of the region which will mean many thousands of 
dollars to the state when the survey is reorganized. 

It is to be sincerely hoped that the Board of Directors of the 
Missouri Survey will follow the wisest course. If the finances of 
the state require the reduction that has been made in the appro- 
priation for the geological survey, let this be only temporary, 
and let the office of state geologist and its present representa- 
tive be retained. Mr. Winslow has held this position since the 
present survey was inaugurated; he has managed the affairs of 
the survey in a most energetic and capable manner, and the vol- 
umes on coal, iron, mineral waters, and other subjects attest to 
the activity of himself and his staff. Much of this work he has 
accomplished in the face of the many difficulties that no one but 
those who have had personal connections with state geological 
surveys can appreciate; and yet his publications speak for them- 
selves in their completeness and the thoroughly scientific meth- 
ods with which he has treated the problems before him. He has 
already performed a great service to the people of Missouri and 
the public in general; and it is to be hoped that the Board of 
Directors will not permit the state to lose the man who is more 
necessary than any other to the successful completion of the 
geological survey. We recur to the hope expressed at the out- 
set that the report of discontinuance is erroneous. 

Ree Aw Eee P in. 

Tue Boston meeting of the Geological Society of America 
was remarkable for the large number of papers submitted, fifty- 
nine, and for the unusual geological activity which these indicated. 
In an uncommon degree the papers represented recent active 
investigations. To only a slight extent were they rehearsals of 


104 IEE SOK AVL Ol? (GIR QULIOGNA, 


old studies. Of the fifty-nine papers presented, eleven may be 
classified as petrological, twenty-two as structural and stratigraph- 
ical, four as physiographic, three as paleontological, eight as 
glacial, four as taxonomic, and the remainder as miscellaneous. 
On the whole, the papers showed wide diversity of interest and 
an admirable distribution of investigation. Notable interest was 
manifested in the petrological papers, particularly those relative 
to volcanic phenomena, and in the papers bearing on structural 
dynamics. The titles were as follows: 


Some Recent Discussions in Geology. (Presidential address). Sir J. 
William Dawson. 

Geological Notes on some of the Coasts and Islands of Behring Sea 
and its Vicinity. George M. Dawson. 

Fossil Flora of Alaska. Frank H. Knowlton. 

New Discoveries of Carboniferous Batrachians. Sir J. William Dawson. 

Cenozoic Geology along the Apalachicola River. William H. Dall and 
Joseph Stanley- Brown. 

Geological Activity of the Earth’s Originally Absorbed Gases. Alfred 
C. Lane. 

Certain Climatic Features of Maryland. William B. Clark. 

Dual Nomenclature in Geologic Classification. H.S. Williams. 

Johann David Schoepff, and his Contributions to North American Geology 
George Huntington Williams. 

Relations of Synclines of Deposition to Ancient Shorelines. Bailey Willis, 

An Account of An Expedition to the Bahamas. Alexander Agassiz. 

Lacustrine Tertiary Formations of the West. William B. Scott. 

Geology of the Coosa Valley in Georgiaand Alabama. C. Willard Hayes. 

Geological Structure of the Housatonic Valley lying east of Mt. Washing- 
ton. William H. Hobbs. 

The Hibernia Fold, New Jersey. J. E. Wolff. 

Tertiary Dislocations of the Atlantic Coast of the United States. N.S. 
Shaler. 

Relations of Mountains to Continents. N.S. Shaler. 

Phenomena of Beach and Dune Sands. N.S. Shaler. 

Eastern boundary of the Connecticut Triassic. W. M. Davis and L. S. 
Griswold. 

Geographical Work for State Geological Surveys. W. M. Davis. 

Facetted Pebbles on Cape Cod. W. M. Davis. 

Paleozoic Intra-formational Conglomerates. Charles D. Walcott. 

Paleozoic Overlaps in Montgomery and Pulaski Counties, Virginia. M.R. 
Campbell. 


EDITORIALS. 105 


The Trias and Jura of the Western States. Alpheus Hyatt. 

The Shasta-Chico Series of the Pacific Coast. J. S. Diller. 

The Cretaceous Faunas of the Shasta-Chico Series. T. W. Stanton. 

‘Geology of Indian Territory and Texas Adjacent to Red River. Robert 
10, Letilll, 

Notes on the Geology of Lower California. S.F. Emmons and G. P, 
Merrill. 

Origin and Classification of the Green Sands of New Jersey. William B. 
Clark. 

Crustal Adjustment in the Upper Mississippi Basin. Charles R. Keyes. 

A Geological Study of Lake Mohonk and Lake Minnewaska, N. Y. Wil- 
liam H. Niles. 

Geologic Relations in the Belt from Green Pond, New Jersey, to Skunne- 
munk Mountain, New York. N. H. Darton. 

A Prismatic Stadia Telescope. Robert H. Richards. 

Ancient Volcanic Rocks along the Eastern Border of North America. 
George Huntington Williams. 

Ancient Eruptive Rocks in the White Mountains. C. H. Hitchcock. 

The Chemical Equivalence of Crystalline and Sedimentary Rocks. G. 
K. Gilbert. 

Volcanite, an Anorthoclase Augite Rock chemically like the Dacites. 
William H. Hobbs. 

Further Notes on the Occurrence of Albertite in New Brunswick, Canada. 
H. P. H. Brumell. 

Alterations of Silicates in Gneiss at Worcester, Mass. Homer T. Fuller. 


Pre-paleozoic Decay of Crystalline Rocks North of Lake Huron. Robert 
Bell. 


Gabbros on the Western Shore of Lake Champlain. James F. Kemp. 

Notes on the Occurrence of Mica in the Laurentian of the Ottawa District. 
Robert W. Els. 

Intrusive Sandstone Dikes in Granite. Whitman Cross. 

Age of the Auriferous Slates of the Sierra Nevada. James P. Smith. 

Origin of the Coarsely Crystalline Vein Granites, or Pegmatites. William 
O. Crosby. 

A Classification of Economic Geological Deposits, based upon Origin and 
Original Structure. William O. Crosby. 

Lake Cayuga a Rock Basin. R.S. Tarr. 

Pleistocene Problems in Missouri. James E. Todd. 

Remarks upon a supposed Glaciated Stone Axe from Indiana. G. Frede- 
rick Wright. 

Pseudo-Cols. TT. C. Chamberlin. 

Certain Features of the Past Drainage Systems of the Upper Ohio Basin. 
T. C. Chamberlin and Frank Leverett. 


106 TIDE WV OORNAL OL ANGHOL OG NA 


Glacial History of Western Pennsylvania. G. Frederick Wright. 

The Ancient Strait at Nipissing. F. B. Taylor. 

Extramoraine Drift between the Delaware and the Schuylkill. Edward 
H. Williams. 

Interglacial Series of Germany. Professor Dr. Alfred Teutzsch, Kénigs- 
berg, Prussia. 

The Madison Type of Drumlins. Warren Upham. 

Diversity of the Glacial Drift along its Boundary. Warren Upham. 

Notes on the Microscopic Structure of Siliceous Odlite. E.O. Hovey. 


Tene: 


TEV LES 


Ritgen. Eine Inselstudie. By DR. RUDOLF CREDNER, Professor in the 
University of Greifswald. Forschungen zur deutschen Landes- und 
Volkskunde, No. 5, Vol. 7. Stuttgart, Engelhorn, 1893. 

Through the special mention of this interesting monograph, I wish 
to call the attention of studious American readers to the valuable series 
of essays, edited by Professor Kirchhoff of Halle, and published under 
the above title. The earlier numbers contain such papers as Dive ober- 
rheinische Trefebene und thre Randgebirge, by Lepsius; Der Hinfluss 
der Gebirge auf das Klima von Mitteldeutschland, by Assmann; Gebirgsbau 
und Oberflachengestaltung der. Sachstischen Schweiz, by Hettner; Dre 
Kurische Nehrung und thre Bewohner, by Bezzenberger; Der Rhein in 
der Niederlanden, by Blink; Die Ursachen der Oberflachengestaltung des 
noraddeutschen Flachlandes, by Wahnschatfe. The numbers announced 
to appear shortly are no less attractive: Dze WNorddeutschen Urstrom- 
systeme, by Berendt; Dze Hife/, by Follmann; Der Loden von Schleswig- 
Fflolstein, by Haas ; Bau und Entstehung des Harzgebirges, by Klockmann; 
Bau und Entstehung des Erzgebirges, by Sauer. ‘There are many others 
of biological or ethnological interest, about forty studies having now 
been published. ‘The price of the separate numbers varies from one to 
eight marks. Subscribers who now purchase the whole series may have 
the first five volumes for half price. 

These studies were begun in) 1882, in consequence of an appeal to 
German geographers and geologists issued by Professor Richard Leh- 
mann. <A central commission was formed, under which various lines 
of work were prosecuted. The most important of these are: the 
Forschungen, here referred to; various bibliographic lists, published by 
local scientific societies, in which everything bearing on home geogra- 
phy is carefully enumerated ; andan Av/deitungen zur Deutschen Landes- 
und Volksforschung, prepared by various experts. An impulse towards 
the scientific study of the Fatherland has thus been given, which is 
bearing rich fruit. The next century ought to see something of the 
kind in this country; for there is a phase of geologico-geographical 
literature that is more appropriately associated with unofficial publica- 

107 


108 TLE NO SRINALESROLMGSLE OLE OGM 


tion than with reports of state or national surveys. At present, how- 
ever, the more active state surveys offer the best approach to work of 
this class, and with the recently increasing interest in physiographical 
investigation, I hope to see chapters of their annual reports devoted to 
well illustrated essays of this character.* 

Riigen, a composite island on the Baltic coast of Prussia, has long 
attracted attention of geologists from the peculiar dislocations of its 
Cretaceous strata, in which glacial till was peculiarly involved; so that 
some observers concluded the dislocations were the product of pressure 
from the advancing ice sheet. Credner now concludes in effect as 
follows: The Cretaceous strata, while still horizontal, were overspread 
by a sheet of till. The compound mass was then, after the disappear- 
ance of the ice sheet, fractured and dislocated in a rather irregular 
manner, although the lines of movement in a measure follow systematic 
courses. A new constructional topography was thus produced ; and a 
_ significant advance was made in its subaérial denudation. Then a 
second ice sheet crossed the Baltic, rubbed over the uneven surface of 
Riigen, softened its surface expression, and distributed an irregular 
deposit of drift over the Cretaceous beds and the older drift. Since - 
then, a moderate depression has submerged part of the region, convert- 
ing Riigen into a group of islands ; and these have been in still later 
times soldered together by sand bars. 

Concerning the evidence thus gained of a complex glacial period, 
Credner remarks: A convincing proof of the long interval between 
the two glaciations is found both in the heavy fracturing and faulting 
that took place between the deposition of the two northern drift forma- 
tions; and in the distinct denudation that was suffered by the construc- 
tional forms produced by the dislocations, before the deposition of the 
second drift (p. 416, 417). 

W. M. Davis. 

See The Improvement of Geographical Teaching, Nat. Geogr. Magazine, IV., 
1893, 74. 


ANALYTICAL ABSTRACTS OF CURRENT 
LITERATURE. 


SUMMARY OF CURRENT PRE-CAMBRIAN NORTH 
JIMS IRI CZSUNE WU JOS A IOUS 


Ells? gives a description of the Laurentian of the Ottawa district. A 
reéxamination of the Trembling Mountain section shows that, instead of its 
being a continuous ascending series, there are no less than three anticlines 
and their corresponding synclines, and the section is still further compli- 
cated by faults of every considerable extent. But one limestone was found, 
that of Trembling Lake, and this instead of being interstratified with 
the orthoclase gneiss is in the form of a synclinal overlying this gneiss. 
This limestone at no point was observed to be more than 50 feet in vertical 
thickness. 

In the region between the anorthosite area and the Gatineau river the 
limestone in nearly every case occupies well defined synclinals separated by 
anticlinals of the underlying gneiss. In this area it has been found impos- 
sible to trace any bands of limestone to any considerable distance con- 
tinuously, the limestones being often local in their development, and lenticular 
in form. 

In the limestone in certain places are masses of quartzose rock and crushed 
gneiss, presenting the aspect of a true conglomerate. As to the thickness of 
the gneiss, on the Rouge river, the most favorable place found for measure- 
ment, the section gave a thickness of 10,000 feet beneath the limestone, if 
there is no break, but this figure may not be accurate, as faults and repetitions 
of strata may occur at several places. 

Intrusive within the gneiss and limestone are the anorthosite and syenite 
masses of Grenville and Chatham, and other less conspicuous masses. No 
less than six or seven clearly distinguished periods of intrusion can be recog- 
nized. The augen gneiss of the Rouge river is probably also an intrusive. 


™Continued from Vol. I., p. 541. 


2The Laurentian of the Ottawa District, by R. W. Etus. Bull. Geol. Soc. of Am., 
Vol. IV., pp. 349-360. 
109 


110 LHE JOURNAL OF GHOLOGY: 


The succession in the district, as determined in ascending order, is (1) 
reddish grey gneiss without distinct signs of bedding or stratification, but with 
a foliated structure ; (2) reddish orthoclase-gneiss interstratified with horn- 
blendic, quartzose, and garnetiferous gneiss and beds of quartzite, the whole 
showing a well stratified arrangement of beds ; (3) grayish and rusty gneiss 
passing gradually upward into the calcareous portion of the system, between 
the gneiss and the limestone there being interstratifications of the two; and 
(4) schistose, sericitic, chloritic, and micaceous schists of the Hastings series. 
This division overlies the crystalline limestone, and is believed to represent 
the lower member of the Huronian system. This arrangement of the Laur- 
entian accords very closely with that in New Brunswick, as given by Bayley 
and Mathew. Unconformable upon -the Laurentian of Ontario is the Pale- 
ozoic. 


Adams‘ describes the anorthosite of Canada, and gives its relations to the 
surrounding rocks. The great mass of the Archean of Canada is composed of 

an orthoclase-gneiss, which is in many places laminated, but is in large part 
little laminated, and probably of eruptive origin. Much of the laminated 
gneiss is probably sedimentary. In certain regions the laminated gneiss is 
interlaminated with crystalline limestones, quartzite, amphibolite, etc. This 
series is a higher part of the Laurentian, and was called by Logan the Gren- 
ville series ; while the lower gneiss, which does not bear any of this rock, was 
called the Ottawa gneiss. The limestone, graphite, etc., are evidences of the 
existence of life during the deposition of the Grenville series, and this was the 
earliest life of the planet. 

All of the minerals of economic importance occur in the Grenville series. 
The relations of the Grenville series to the Ottawa series have not been 
certainly determined, but it is probable that the Grenville series lies discord- 
antly upon the old gneiss, the upper series being sediments originally like 
those that are deposited to-day. 

The anorthosite group, or Upper Laurentian of Logan, is an eruptive rock 
belonging to the gabbros. It is characterized by a predominance of plagio- 
clase, which frequently is the only mineral of the rock. The rock is hard and 
originally was completely massive. This original structure has been modified 
so as to take on an extraordinary cataclastic structure, which has also given the 
rock a schistose character. This is not ordinary dynamic metamorphism, but 
is caused by a movement of the rock mass while it was deeply buried and 
near its melting point. 

The anorthosite, although so regarded by Logan, is not a distinct sedi- 


tNorian oder Ober-Laurentian von Canada, ADAMs, F. D. Inaugural-Dissertation 
zur Erlangung der Doctorwurde der Universitat zu Heidelburg. 1893. 


UN AIL SIM CAG, AI ERS IGA CE IOS AG tal 


mentary geological formation, but it is discordantly upon the gneiss of the 
Laurentian by intrusion. Its intrusive character is shown by the following 
facts: itis a plagioclase gabbro; it cuts across the Laurentian schists ; it holds 
as inclusions blocks of gneiss; about its masses forming girdles are many 
characteristic contact belts. The areas of anorthosite are isolated, and lie 
along the border of the Archean continent of that time exactly as the volcanoes 
of to-day are along the continental borders. In the great interior area of 
Laurentian no anorthosite has beenfound. The formation is all pre-Cambrian, 
as shown by the fact that it les unconformably below the Cambrian. Also 
before the Cambrian was deposited it received its metamorphism, and was 
deeply eroded. Its relations to the Huronian have not been determined, but 
it probably does not belong to the Huronian period, but rather to the closing 
part of the Laurentian. 

The several regions of anorthosite are described separately, that of Morin 
and Saguenay being most fully considered. The Morin area is surrounded 
by the Grenville series. In the Grenville series are interlaminated limestones, 
bands of which can be traced many miles. Within the limestone are 
frequently thin layers of the gneiss. The limestone is less resistant and more 
plastic than the gneiss. As a result of folding, the bands of gneiss have been 
broken up, producing irregular banded blocks, which are isolated in the 
limestone in such a manner as to give rise to extraordinary pseudo-con- 
glomerates. 

The Saguenay region is of great size, 5,800 square miles. It is surrounded 
on all sides by the orthoclase-gneiss, or Ottawa gneiss. The anorthosite of 
this district is more basic than that of the Morin district, the plagioclase 
frequently being labradorite or bytownite. That it is an intrusive is shown by 
the same facts as in the Morin area. 

Comments.—The time of pre-Cambrian life must have been so vast that it 
is not safe to assume that the rocks of the original Laurentian bear the 
remains of the first life of the planet. Indeed, it seems probable that the 
earliest life left in the rocks no permanent evidence of existence. Further, 
before it can be assumed that the Ottawa Laurentian bears the oldest 
remains of life, it must be shown that these rocks are older than any other 
series bearing life remains. . 


Adams describes the typical Laurentian areas of Canada.t The basement 
rock here found is the Fundamental Gneiss. It is uniformly reddish or grayish 
orthoclase-bearing gneissoid granite, poor in mica, and bisilicates. The foliation 
is often due to movement in a plastic condition. Dark bands of amphibolite 


*On the Typical Laurentian Areas of Canada, by FRANK D. ADAMS. Journal of 
Geol., Vol. I., No. 4, pp. 325-340. 


ee THE JOURNAL OF GEOLOGY. 


are not uncommon, and hornblendic and pyroxenic gneiss appears in some 
places. The Fundamental Gneiss, so far as at present known, is a compli- 
cated series of rocks, for the most part of unknown origin, but comprising a 
considerable amount of intrusive material. 

In certain parts of the Laurentian area, and notably in the Grenville dis- 
trict, the Laurentian has a different character. In the Grenville series the 
orthoclase-gneiss is still the predominating rock, although it here has a greater 
variety of mineralogical condition, and is frequently well foliated. Amphibo- 
lites, hornblende-schists, heavy beds of quartzite, and numerous thick bands 
of crystalline limestones, are all abundant and interstratified with one another. 
In the series are ores, and a wide variety of minerals. In the limestone and 
associated rocks graphite is often widely disseminated. This does not occur 
in the Fundamental Gneiss. The areas occupied by the Grenville series 
while together aggregating many thousands of square miles, are probably 
small as compared with those of the Fundamental Gneiss. The Gren- 
ville rocks, while generally highly inclined, over some large area are 
nearly horizontal, but even in these cases they have been subjected to great 
pressure. 

As to the origin and relations of the Fundamental Gneissand the Grenville 
series, three views may be taken : 


1. The Fundamental Gneiss may be the remains of a primitive crust pen- 
etrated by great masses of igneous rocks and having been subjected to 
repeated dynamic movements. The Grenville series may be an upward con- 
tinuation of the Fundamental Gneiss under altered conditions, marking a 
transition from a primitive crust to normal sediments. Thus the two would 
form one practically continuous series. The general petrographical similar- 
ity of the two series, taken in connection with the more varied nature of the 
Grenville series, its frequent stratified character, and the presence in it of 
limestones and graphite indicating an approach to modern conditions and the 
advent of life, together with the difficulty of clearly separating the two series 
from each other and defining their respective limits, lend support to this 
view. 

2. The Grenville series may be considered as distinct from the Funda- 
mental Gneiss, and reposing on it uncomformably, being a highly altered 
series of clastic origin, the Fundamental Gneiss having some such origin as 
suggested above or being an older series of still more highly altered sedi- 
ments. As it is now thoroughly crystalline, there is, however, no absolutely 
conclusive proof that even the Grenville series is of sedimentary origin. How- 
ever, the series is in all probability made up, in part at least, and perhaps 
wholly, of sedimentary material, but as this is not absolutely shown, the pro- 
posal to separate it from the rest of the Laurentian and class it as Algonkian 
or Huronian seems premature. 


ANALYTICAL ABSTRACTS. et) 


3. The Fundamental Gneiss may be considered as a great mass of erup- 
tive rock, which has eaten upward and penetrated the Grenville series, while 
the Grenville series itself represents a series of altered sediments of Lauren- 
tian, Huronian, or subsequent age. The world wide distribution of the Fun- 
damental Gneiss (forming as it does, wherever the base of the geological 
column is exposed to view, the foundation upon which all subsequent rocks 
are seen to rest) is opposed to this view, as is also its persistent gneissic or 
banded character. 

The anorthosite series is a gabbro, often regularly laminated and much 
altered, which is intrusive within the Fundamental Gneiss and the Grenville 
series. 

The Hastings series has a very local development. It consists largely 
of calc-schists, mica-schists, dolomites, slates, and conglomerates, thus con- 
taining much material of undoubtedly clastic origin. The whole district has 
been subjected to great dynamic action, some of the pebbles of the conglom- 
erates being distorted in the most remarkable manner. This series may be 
equivalent to a part of the original Laurentian, may follow above the Gren- 
ville series, or may pruve to be an outlying area of Huronian rocks folded in 
’ with the Laurentian. 

The whole of the above series was cut by various acid and _ basic 
rocks, metamorphosed and folded before upper Cambrian time, since the 
Cambrian sediments rest upon them unconformably, and contain fragments 
of the lower series which show that when déposited they were in their present 
condition. 

The roche moutonnée surface possessed by the eroded Laurentian rocks 
was impressed upon them in the first instance in pre-Cambrian times, for 
along the edge of the nucleus from Lake Superior to the Saguenay, the Paleo- 
zoic strata may be seen to overlie such surfaces showing no traces of decay, 
and similar to that exposed over the uncovered part of the area. To what 
extent the Cambrian, Devonian, and Silurian seas passed over the Laurentian 
cannot be determined, but it seems probable that in Cambrian times, a not 
inconsiderable part of the Archean Nucleus was under water, as shown by 
various outliers of these rocks. What evidence there is indicates that the 
area in later Paleozoic, Mesozoic, and earlier Tertiary times, was out of water, 
being subjected to deep-seated decay and denudation, culminating in the 
glaciation of Pleistocene times. These processes removed all but remnants 
of the Paleozoic strata. 

Comments.—The question may perhaps be asked whether the visible con- 
tacts of the pre-Cambrian and Cambrian are sufficiently extensive to warrant 
the statement that the pre-Cambrian topography was similar to the present 
topography. May not the tendency to carry in imagination the present forms 
under the Cambrian have been given undue weight? 


1h 1 /A\ THE. JOURNAL OF NGEHOLOGN. 


Lawson,‘ in 1893, on lithological grounds suggests the following hypothet- 
ical correlation of certain rocks of Western Qntario and Minnesota, Eastern 
Ontario and Quebec : 


Hee ONT SRI | EASTERN ONTARIO UEBEC 
AND MINNESOTA. : Q : 
Ontarian system. Hastings series. Grenville series. 
In order of superpo- : ; 3 
an ele Laurentian system. Ottawa gneiss. Ottawa gneiss. 
Carltonian-Anortho- 
sites of Minne- Norian. 
sota. 
Carltonian-Anortho- 
sites of Minne- Norian. 
sota. 
In order of chrono-|— 
logical sequence; an|a . Ai 
sees: oe -< ¢ | Batholitic 
irruptive rock being of|¢ 3 : : , 
ES EO ee granites and Ottawa gneiss. Ottawa gneiss. 
Ae: . Peewee eS phan oMeISSES. 
mations which it in-|3 # 
vades. A 
Ontarian system. Hastings series. Grenville series. 


Comments.—It seems to the reviewer that such lithological correlations 
between rocks in different and widely separated geological provinces have no 
value. The reasons for this belief cannot be here stated, but they have been 
published in Bull. No. 86, U. S. Geol. Survey. 


Barlow? describes the Laurentian granites and gneisses as intrusive in the 
Huronian rocks north of Lake Huron. The localities described are Killarney 
Village; Beaver, Fox, Balsam, Three Mile, Brush, Camp, Crooked, Johnny, 
Panache, Wavy, Chief's, Daisy, Baby and Alice lakes; Goshen, Broder and 
Dell townships ; Wahnapital river ; Cartier and Straight Lake Stations ; and two 
islands near Thessalon. As evidence of the eruptive nature of the Laurentian 
gneiss in the Huronian sediments are cited the diverse stratigraphic relations 
of the rocks along their line of junction ; the invariable alteration of the sedi- 
mentary rocks along the contact line; the inclusion of angular fragments, 
clearly referable to the adjacent sedimentary strata in the gneiss ; the occur- 
rence of gneissic intrusions and apophyses of pegmatite, occurring in or lam- 

«The Norian Rocks of Canada, by A. C. Lawson. Science, Vol. XXI., No. 538, 
pp. 281-282. 


2 Relations of the Laurentian and Huronian Rocks North of Lake Huron. By A. 
E. Bartow. Bull. Geol. Soc. of Am., Vol. IV., pp. 313-332. 


/ 
ANALYTICAL ABSTRACTS. IIs 


inated with, and cutting across the bedding of the Huronian rocks; the 
absence of sedimentary rocks within the gneiss, and the general character of 
the gneiss, which in appearance and behavior more nearly resembles an erup- 
tive granite than an altered sedimentary rock. It is therefore concluded that 
the Huronian is the oldest series of sedimentary strata in this region, and that 
the floor upon which these were lain down must have been subsequently fused 
and recrystallized. 

Comments.—That in many localities there are granites and gneissoid 
granites intrusive in the Huronian of Lake Huron has been well known since 
the days of Logan. However, because a part of the granites are intrusives 
later than the Huronian, this does not show that the basement upon which the 
Huronian was laid down does not still exist, in part at least, as held by Logan, 
Irving, Pumpelly, and others. The account of the facts and their interpreta- 
tion at the contacts near Thessalon by Barlow are so irreconcilable with those 
given by Pumpelly, Irving, and myself, that the former or the three latter must 
have wholly failed to grasp the truth. These latter hold that there is here the 
most manifest evidence of profound unconformity between the Basement Com- 
plex and the Huronian. Should this position prove correct, the question 
would naturally arise as to what extent the accounts of the remaining localities 
described by Barlow need revision. 


Smith,’ in 1893, gives a general description of the Archean rocks in the 
southern half of the Rainy Lake district in the Province of Ontario, between 
the Thunder Bay district and the Lake of the Woods. The rocks here found 
are divided into the Lower Archean and Upper Archean, the term Archean 
being defined to include all pre-Cambrian rocks. The Lower Archean series, 
or Laurentian, comprises a lower granitic and syenitic division, and an upper 
micaceous, hornblendic and trappean division, for the most part schistose. 
The first usually occurs in rounded or ovoid areas, between which are the 
rocks of the Upper Archean or Ontarian. 

The Ontarian system includes the Contchiching and Keewatin series. The 
Contchiching rocks are mainly mica-schists, and have an estimated thickness 
of 9,000 feet, the apparent thickness of 24,000 to 29,000 feet, given by Dr. 
Lawson, being believed to be due to multiple folds. These mica-schists are 
regarded as clastic in origin, because of their fine and even lamination. The 
Keewatin consists for the most part of plutonic, volcanic, and pyroclastic rocks, 
although in some of the upper members there are more or less aqueous sedi- 
ments. The Contchiching and Keewatin are everywhere in strict conformity, 
although at the base of the Keewatin in certain localities there are conglom- 
erates regarded as local and volcanic. 


The Archean Rocks West of Lake Superior. By W. H.C. Smiru. Bull. Geol. 
Soc. Am., Vol. IV., pp. 333-348. 


116 THE JOURNAL OF GEOLOGY. 


The Laurentian granites and gneisses are intrusive in the Ontarian, and 
are therefore younger, the relations between the two being the same as 
described by Lawson in the Rainy Lake district. 

Resting discordantly upon the Laurentian and Ontarian rocks, is the 
Steep Rock series, presumably of Archean age. This series is believed to be 
a folded syncline, rather than a monocline, as described by Smyth. As the 
Animikie series exhibits no such folding, the inference is strong that the Steep 
Rock series is older than the Animikie. While the unconformity between the 
Steep Rock series and Laurentian is undoubted, the unconformity between 
the Keewatin of the Seine river and the Steep Rock Lake series is not at all 
obvious. Lithologically the two series are strikingly similar, and could not be 
separated by the most careful study. It would seem that to the west of Steep 
Rock Lake this series hasbeen faulted up and swept away, so that it is really 
unconformably above the Keewatin. The Atic Oban series is an eruptive 
one probably belonging to the Keewatin. 

Comments.—Since the Steep Rock Lake series is almost identical in char- 
acter with the Keewatin, the assumption of profound faulting and erosion to 
explain the absence of the former series west of Steep Rock Lake seems 
purely gratuitous, the natural explanation being that the two are the 
same, and that the discordance at the base of the Steep Rock series is marked 
in other localities by the occasional conglomerates described by Lawson and 
Smith at the base of the Keewatin. That unconformities are partly obliterated 
or difficult to discover when the discordant series are closely folded is well 
known, and that a break, if such exists at the base of the Keewatin, should 
be so strongly marked everywhere as at Steep Rock Lake could not be 
expected. A conglomerate in itself is of course no evidence of unconformity, 
but the conglomerates at the base of the Keewatin are of such a character 
that Dr. Lawson, who has studied the district, believes that they mark, if not 
a real unconformity, a profound change of physical conditions between the 
Contchiching and Keewatin. Also he holds that these conglomerates are sedi- 
mentary, rather than volcanic. 

Fine and even lamination, it may be said, is not sufficient evidence that 
the rocks showing this structure are clastic. Such structures are found both 
in metamorphosed igneous and sedimentary rocks. Moreover, it cannot be 
assumed that such a structure corresponds with bedding, even if the rocks are 
clastic. Hence, until it is shown that the two do correspond, determinations 
of thickness based upon lamination can have little value. 


Buell* describes and maps the Waterloo quartzite areas. These are a 
series of detached outcrops resting unconformably under the Lower Silurian 


* Geology of the Waterloo Quartzite Area. By I. M. BuELL. Trans. Wis. Acad. 
Sci., Vol. [X., pp. 255-274. 


ANALYTICAL ABSTRACTS. 117 


of Southern Wisconsin. Within the quartzite are occasional layers of con- 
glomerate. The different outcrops are apparently parts of a synclinal fold. 
As a result of the shearing much of the quartzite has been crushed, and seri- 
cite has developed. 


Van Hise* considers the dynamic phenomena shown by the Baraboo 
quartzite ranges of Central Wisconsin. These rocks, indurated by cementa- 
tion, exhibit all stages between massive quartzite showing microscopically 
little evidence of interior movement, through a rock having in turn fracture 
and cleavage, to one which is apparently a crystalline schist, but in thin 
section still giving evidence of its fragmental origin. The schistosity pro- 
duced by the movement of the layers over one another is parallel to the 
bedding. In places Rezbungs breccias have developed. At one point minor 
faulting was noticed. These phenomena are more marked in the North Range 
than in the South Range, and thus bear in favor of Irving’s explanation of the 
structure as a part of a single great fold in a set of layers 12,000 feet thick, 
the North Range being on the leg of the fold, and thus requiring greater 
readjustment of the beds than those on the South Range, which are near the 
crown of the anticline. 


Winslow,? in 1893, places in the Archean the granites, porphyries, and 
felsites of Missouri, and in the Algonkian the associated conglomerates, one of 
them bearing the Pilot Knob iron-ore. 


Keyes,3 in 1893, holds that the granites of Maryland are eruptive, since 
these rocks indiscriminately cut across the other igneous rocks of the region, 
as well as the gneiss ; because they hold inclusions of the other rocks of the 
region ; because the rocks cut show contact phenomena, and because a micro- 
scopical examination shows that they possess all the characters of rocks cooled 
from fusion. 


Smyth,‘ in 1893, describes the rocks of Gouverneur, N. Y. The gneiss 
gives evidences of mechanical deformation in the shattering of the quartz and 


™Some Dynamic Phenomena Shown by the Baraboo Quartzite Ranges of Central 
Wisconsin, by C. R. Van Hise. Journ. of Geol., Vol. I., No. 4, pp. 347-355. 

?The Geology and Mineral Products of Missouri, by ARTHUR WINSLOW. From 
“Missouri at the World’s Fair.” (Official Publication of the World’s Fair Commission 
of Missouri). 

3Some Maryland Granites and Their Origin, by C.R. KEveEs. Bull. Geol. Soc. of 
Am., Vol. IV., pp. 299-304. 

4 Petrography of the Gneisses of the Town of Gouverneur, N. Y., by C.H. SMyTu, 
Jr. Contributions from the Geol. Dept. of Columbia College. Reprinted from Trans- 
actions of the New York Academy of Sciences, Vol. XII., pp. 203-217. 


118 LTE, OOKIVAL FOL ANGEOLOGN 


feldspar particles. Within the feldspar, along the cracks, microperthite has 
developed which does not show any dynamic action. The granite is much 
later than the gneiss, but like it has to some extent suffered from dynamic 
action. In general it is massive, or nearly so, but there are zones of shearing 
where granulite and gneiss have developed. Also in one portion there is a 
dark rock approaching a diorite, into which the granite grades, but this is 
regarded as a basic segregation from the original magma. The crystalline 
limestone is rather uniform in its character, but where intruded by the granite, 
it is more coarsely crystalline, and various metamorphic minerals have devel- 
oped. Near the base of the limestone is a pyroxenic rock which is schistose, 
highly contorted, and is of somewhat doubtful origin, in the field being 
regarded as sedimentary, and under the microscope having an appearance 
which suggests an igneous origin. In this pyroxenic gneiss occasionally 
scapolite is found. The Potsdam isa pure vitreous quartzite, indurated by 
the process of cementation. 


Nason,’ in 1893, describes the gneissic rocks bearing iron-ore in the 
Adirondack region as precisely like the Mt. Hope type of rock, bearing the 
New Jersey magnetites, and it is thought that the two are probably contem- 
poraneous, bedded deposits. These gneissic ores are non-titaniferous, and are 
to be discriminated from the titaniferous iron ores which are associated with 
the labradorite rocks or norites of the region. These in occurrence and 
association are wholly distinct from the ores belonging in the gneisses. 


Lawson? describes the Santa Lucia granite of Carmelo Bay as resting 
unconformably below the sedimentary rocks (Miocene) of the Carmelo series. 
At the base of the latter is a fine basal conglomerate. Across the Bay of 
Monterey, in the Santa Cruz range, granite without doubt of the same geol- 
ogical range bears a similar relation to rocks which are of not later age than 
Cretaceous. The granite is therefore, at the latest, of pre-Cretaceous age. 

C. R. VAN HisE- 


«Notes on Some of the Iron-bearing Rocks of the Adirondack Mountains, by F. L. 
Nason. Am. Geol., Vol. XII., No. 1, 1893, pp. 25-31. 

2The Geology of Carmelo Bay, by A.C. Lawson. Bull. Dept. Geol., Univ. of 
Cal., Berkeley, Vol. 1., pp. 1-59. 


ACKNOWLEDGMENTS. 


The following papers have been donated to the library of the Geological Depart- 
ment of the University of Chicago, mainly by their authors : 
BARLOW, ALFRED E. 

—Relations of the Laurentian and Huronian Rocks north of Lake Huron. 

314-332 pp.—Bull. Geol. Soc. Am., Vol. IV., Aug. 4, 1893. 
BARROIS, CHARLES. 
Légende de la Feuille de Dinan. 25-40 pp.—Extrait des annales de la 
société géologique du Nord, T. XXI., Feb., 1893. 


—Sur le Rouvilligraptus Richardsoni de Cabrieres. 107-112 pp., 2 Pl.—Ibid., 

March, 1890. 
BENECKE, E. W. Dr. 

—Mittheilungen der Geologischen Landesanstalt von Elsass—Lothringen. 72 

pp., 8 Pls.—Band. IV., Heft. 2. 
BLAKE, WILLIAM B. 

—The Mineral Deposits of Southwest Wisconsin. 11 pp.—Engineering Con- 
gress, Aug., 1893. 

—The separation of Blende Pyrites. 6 pp. 

Brown, H. Y. L., F.G.S. 

—Catalogue of South Australian Minerals, with the mines and other localities 
where found ; and brief remarks on the mode of occurrence of some of the princi- 
pal metals and ores. 34 pp.—1893, 

CALLAWAY, CHARLES, D.Sc., M.A., F.G.S. 

—The Origin of the Crystalline Schists of the Malvern Hills. Pp. 3908-42 5.— 

Quart. Jour. Geol. Soc., Aug., 1893. 
GEOLOGICAL SURVEY OF CANADA. 

—Catalogue of Section 1 of the Museum of the Geological Survey. 256 pp.— 
1893. 

—Catalogue of the Stratigraphical Collection of Canadian Rocks, prepared 
for the World’s Columbian Exposition. 131 pp. 

—Maps accompanying Annual Report. Vol. IV., 1888-9. 

CARPENTER, P. HERBERT, M.A. 
—On a New Crinoid from the Southern Sea. Pp. 919-933.,1 Pl.—Phil. Trans 
Roy. Soc., Part III., 1883. 
CARTER, OSCAR C. S. 
—Artesian Wells. 10 pp.—Proc. Chem. Soc. Franklin Inst., Sept., 1893. 
CHALMERS, ROBERT. 

—Height of the Bay of Fundy Coast in the Glacial Period Relative to Sea 
Level, as evidenced by Marine Fossils in the Bowlder Clay at Saint Johns, New 
Brunswick. Pp. 361-370.—Bull. Geol. Soc. Am., Vol. IV., Aug., 1893. 

119 


120 WEES, JKOWUAAIE OUP (HX OLOGY, 


CLARK, WILLIAM B. 

—On Tertiary Deposits of the Cape Fear River Region. Pp. 537—540.—Bull. 
Geol. Soc. Am., Vol. I. 

—A Revision of the Cretaceous Echinoidea of North America. 8 pp.—Johns 
Hopkins University Circulars, No. 86. ; 

—The Discovery of Fossil-Bearing Cretaceous Strata in Anne Arundel and 
Prince George Counties, Maryland. 6 pp.—lIbid., No. 69. 

—Third annual Geological Expedition in Southern Maryland and Virginia. 7 
pp.—lIbid., No. 81. 

—Ueber die Geologischen Verhaltnisse der gegend Nordwestlich vom Achen- 
See mit besonderer Beriicksichtigung der Bivalven und Gasteropoden des unteren 
Lias. 46 pp., 2 pl., 1 map colored. 

—A New Ammonite, which throws additional light upon the Geological Posi- 
tion of the Alpine Rhaetic. 4 pp.—Am. Jour. Sci., Feb., 1888. 

—On the Origin, Structure, and Sequence of Sedimentary Rocks. 45 pp. 

— Geological Features of Gay Head, Mass.—Johns Hopkins University Circu- 
lars, Dec., 1890. 

—Report of the Scientific Expedition in Southern Maryland. 3 pp.—lbid., 
June, 1891. 

—Reports upon short Excursions made by the Geological Department of the 
University during the autumn of 1891. 3 pp.—Ibid., Feb., 1892. 

—Eocene of the United States.—Ibid., Feb., 1893. 

——Mesozoic Echinodermata of the United States.—Ibid., Feb,, 1893. 

—Preliminary Report on the Cretaceous and Tertiary Formations of New Jer- 
sey. Pp. 169-445.—Annual Report of New Jersey, 1893. 

—Bibliographia Hopkinsiensis, 1876-93. Pp. 31-50. 

—Geology and Physical Features of Maryland. 67 pp., 16 pl., 1 Map colored. 

—World’s Fair Book on Maryland, 1893. 

—Surface Configuration of Maryland. Maryland State Weather Service, 
Monthly Report for March, 1893. 4 pp. 

—Leading Features of Maryland Climate. 6 pp.—lbid., May, 1893. 

—Public Water Supply in Maryland. 2 pp.—Ibid., July, 1893. 

—Correlation papers Eocene. 173 pp.,2 maps.—Bull. U.S.G.S., 1891, No. 83. 

—The Mesozoic Echinodermata in the United States. 102 pp., 49 pl.—Bull. 
U.S.G.S., No. 97. 

—On Certain Aspects of Local Geology.—The Vermont Phcenix, May 20, 1892. 

CLAYPOLE, E. W. 

—On Pteraspidian Fish in the Upper Silurian Rocks of North America. Pp. 

47—64.—Quart. Jour. Geol. Soc., Feb., 1885. 
DALL, W. H. 

—On some Fossil Unios and other fresh water shells from the drift at Toronto, 
Canada, with a review of the Distribution of the Unionidee of Northeastern 
North America (by Charles T. Simpson). Pp. 591-595.—Proc. U.S. Nat. Mus., 
Vol. XVL., 1893. 

Ets, R. W. 

—The Laurentian of the Ottawa District. Pp. 349-360.—Bull. Geol. Soc. Am., 

Vol. IV., Aug., 1893. 


ACKNOWLEDGMENTS. 121 


ETHERIDGE, R., JR. 
—On Additional Silurian and Mesozoic Fossils from Central Australia. 8 pp., 
1 pl.—Supplement to Parliamentary Papers, No. 158, 1891; No. 23, 1892. 
FROSTERUS, BENJ. 
—Ueber ein neues Vorkommnis von Kugelgranit unfern Wirvik bei Borga in 
Finland, nebst Bemerkungen tiber ahnliche Bildungen. 34 pp., 2 pl. 
GILL, A. CAPEN. 
—Beitrage zur Kenntniss des Quarzes. 35 pp., 2 pl.—Zeit fiir Krystallogr. u. 
Mineralogie, XXII. Bd. 2. Heft. 
GRANT, ULYSSES SHERMAN. 
—Field Observations on Certain Granitic Areas in Northeastern Minnesota. 
Pp. 35-110.—2oth Annual Report Minn. Geol. Surv. 
Ho.iMEs, Mary E. 
—The Morphology of the Carinz upon Septa of Rugose Corals. 31 pp., 26 
pls.—1887. 
LAWSON, ANDREW C. 
—The Geology of Carmelo Bay. 159 pp., 4 pls.—Bull. Univ. of Cal., May, 
1893. 
—Anorthosytes of the Minnesota Coast of Lake Superior. 
—The Laccolitic Sills of the Northwest Coast of Lake Superior. 48 pp., 5 
pls.—Geol. Surv. Minn.,; 1893. 
LERCH, OTTO, PH. D. 
—A Preliminary Report upon the Hills of Louisiana, south of the Vicksburg, 
Shreveport and Pacific Railroad, to Alexandria, La. Pp. 57-158. 
MERCER, HENRY C. y 
—WNotes taken in December, 1892, and March, 1893, at the Quaternary Gravel 
Pits of Abbeville, St. Acheul, and Chelles. Pp. 122-127.—The Archeologist, 
July, 1893. 
MarsH, O. C. 
—Description of Miocene Mamalia. 6 pp., 4 pls.—Am. Jour. Sci., Nov., 
1893. 
MarTIN, FRED. W., F.G.S. 
—Bowlders of the Midland District. 22 pp., 1 map.—Proc. Birmingham Phil. 
Soc., Vol. VII., Part I. 
MERRIMAN, MANSFIELD. 
—The Strength and Weathering Qualities of Roofing Slates. Pp. 331-349.— 
Am. Soc. of Civil Engineers, Vol. XXVIL., Sept., 1892. 
ORTON, EDWARD. 
—Ohio Geological Survey, 1869-70, Geology, 1873-78. Vols. 1, 2, and 3, with 
maps accompanying Vols. I and 2. 
PALACHE, CHARLES. 
—The Soda-Rhyolite north of Berkeley. 10 pp., 1 pl.—Bull. Univ. Cal., Vol. 
I. Pp. 61-72, May, 1893. 
PITTIER, HENRIQUE PROFESSOR. 
—Boletin Trimestral del Instituto Meterologico Nacional, Nos. 1, 2, 3, 4, 1888. 
—Annales de Instituto Fisico-Geografico Nacional. T. II., Part I., IL, 
1890. 


P22, THE JOURNAL OF GEOLOGY. 


SCHMIDT, C. 

—Metamorphose des roches alpines. 3 pp.—Extrait des Archives des Sciences 
physiques et naturelles. T. XXVIII., Noy., 1892. 

—NMittheilung tiber Moranen am Ausgange des Wehrathales. 2 pp.—XXV. 
Versammlung des Oberrheinischen geologischen Vereins zu Basel. 

—Ueber zwei neuere Arbeiten betreffend die Geologie des Kaiserstuhles om 
Breisgau. Pp. 255-277, Ill—Verhandlungen der Naturforschenden Gesell. in 
Basel, Vol. X., Heft. 2. 

SMITH, WILLIAM HENRY CHATTERTON. 

—The Archean Rocks west of Lake Superior. Pp. 333-348.—Vol. 4, Aug., 

1893. 
STEINMAN, G. 

—Die Moranen am Ausgange des Wehrathals. 5 pp.—XXV. Versammlung 
des Oberrheinischen geologischen Vereins zu Basel. 

—Ueber die Gliederung des Pleistocan im badischen Oberlande. Pp. 745-791. 

—Aus dem Mitt. der Grossh. Badischen Landesanstalt. II., Bd. XXI., 1893. 

TARR, RALPH S. 

—Notes on the Physical Geography of Texas. Pp. 313-347.—Proc. Acad. 
Nat. Sci., Phila., Aug. 29, 1893. 

—Glacial Erosion. 6 pp.—Am. Geol., Vol. XII., Sept., 1893. 

TOPINARD, PAUL, DR. 
—L’Anthropologie aux Etats-unis. Pp. 301-351.—Extrait de L’Anthropologie 
de May-June, 1893. 
UpHAM, WARREN. 
—A\ltitude as the Cause of the Glacial Period. 2 pp.—Science, Aug. 11, 1893. 
WoopworTH, J. B. 

—Attempt to estimate the thickness of the ice blocks which gave rise to lakelets 

and kettle-holes. Pp. 279-284.—Am. Geol., Noy., 1893. 


(Further acknowledgments of pamphlets already recetved will be made tn the next 
number.) 


\ 


THE 


JOWINN A OF GEOLOGY 


FEBRUARY-MARCH, 1894. 


THE GLACIAL SUCCESSION IN NORWAY. 


AS SCANDINAVIA was unquestionably the chief center of the 
great North European glaciation, it follows that Norway is a 
country of glacial denudation rather than of glacial deposition. 
A complete apprehension of its Quaternary history is, therefore, 
not possible solely through the study of the deposits. The 
great marks of erosion are to be taken into consideration. We 
thus come immediately upon the great problem: How far are 
we to go in our acceptance of glacial erosion? It is of course 
impossible here to enter into the whole vexed question. It 
is, however, necessary to briefly summarize some of the reasons 
which lead the geologist in Norway to admit an erosion of so 
great degree, that both our fjords and lakes fall wholly within its 
limits. The most convincing argument is, perhaps, the fact that 
the great North European diluvial plain contains Scandinavian 
detritus in such immense quantity that the rock basins in Scan- 
dinavia could be refilled and replenished many times with it. 
A. Helland has calculated that the German and Russian diluvial 
sheet could fill not only the Scandinavian lakes, but also the 
Baltic, and still heighten the whole peninsula 25 metres (80’). 
And besides, we have the enormous quantity of Norwegian rock 
detritus which forms the bottom of the North Sea and the broad 
submarine plateau to the west of northern Norway. Even if 
this estimate is not entirely correct, it is impossible to deny that 
such enormous quantities of drift have been removed from Nor- 
way in Quaternary time that we must look for marks of denu- 


dation of quite as great degree as our lakes and fjords. 
123 


L224, THE JOURNAL OF GEOLOGY. 


An estimate of the volume of rock matter which is carried by 
the glacial rivers of Greenland and Norway proves also that the 
glacier denudation in a few thousand years must reach great 
dimensions. 

When thus the capacity of the rock basins comes short of hold- 
ing the known glacial sediment (the quantitative element), the 
form of the basins (the qualitative element) is quite in harmony 
with those we find in other glaciated countries and xowhere else. 
Both the lakes and the fjords have a distinguishing trough shape, 
with flat bottoms and comparatively steep sides, in the transverse 
section, and, in the longitudinal section, a gradual deepening 
toward a point that is situated not very far from the outer end, 
against which it more suddenly shoals up. This form cannot be 
generated by any other possible eroding agent than glacier ice. 
- The fissure theory is out of the question, as exact sections specific- 
ally show. Faults and dislocations cannot account for their 
specific form and their relations to quite superficial topographical 
features. The admirable monograph on the Kristiania fjord, by 
Professor W. C. Brégger, makes it also quite clear that its dis- 
tinguishing fjord character can only be of glacial origin. Basins 
of this form, as is well known, are restricted to glaciated coun- 
tries ; and they can be deduced directly from the motion of the 
eroding glacier. The movement must accelerate towards the 
point where the ice surface intersects the snow line, where the 
surplus ice from the whole glacier must pass. Thence it must 
slacken because of the melting farther down. The erosion, which 
naturally must depend both on the movement and the pressure 
of the ice, will decrease accordingly. In this we find the explan- 
ation both of the longitudinal form of the glacial basins, and*of 
their evident dependence on the margin of the land ice. 

So much may be said about glacial erosion by way of intro- 
duction before entering into the study of the succession of glacial 
events in Norway. We must be somewhat prepared to face the 
greatness of the phenomena, which only glacial studies can make 
more familiar to us. 

When we try to realize the appearance of Norway in fre- 


GLACIAL SUCCESSION IN NORWAY. 125 


glacial time,—. ¢., before the Quaternary age—we have not much 
on which to -base our ideas. The immense denudation has so 
thoroughly altered the physiognomy of the country that we are 
quite at a loss to reconstruct it. Wecan only suppose that no 
great change in the relative heights of the mountain plateaus has 
taken place and that there are left, perhaps, in the mountain 
bosses remnants of the original surface. The coast line we are 
no doubt justified in putting farther outwards than now. The 
great slope to the ocean deep does not follow the present coast, 
but is up to 200 kilometers distant, the intervening bank not 
reaching beyond 400 meters. The flora and fauna of Spitzbergen 
and Iceland must have immigrated across this now sunken north- 
western foreland. Near Storeggen (about 62°) G. O. Sars found, 
by dredging at 100 to 200 fathoms (200 to 400M.), remains of a 
littoral fauna and beach shingle, which can only belong to a pre- 
glacial coast. It must therefore be a legitimate inference that 
the country in late preglacial times was, at least at the coast, 
200 to 400 meters higher than now. 

On the mountains in this high country there now began to 
gather great snow masses, the climate deteriorating owing to 
causes that cannot be treated here.t. The névés gradually coa- 
lesced and the glaciers flowed down to the lower land. If the 
present numerous fjords had a preglacial existence they must 
have represented themselves as a close series of deep lakes or 
fjords into which the glaciersoon crept. But beyond such a row 
of ready outlets no continuous ice margin could possibly grow. 
The depth of Sognefjord is 1,250 meters, of Hardangerfjord 800 
meters, though both are rather shallow at their mouth. If the 
whole country was elevated 200 to 400 meters, we still would have 
so deep waters, that any glacier, which could not at once move 
forward with a thickness of 1,000 meters, would get afloat and be 
dissolved into icebergs as fast as it could grow. So any advance 
of inland ice (which necessarily increases but slowly) must 


‘I have given my reasons for accepting a shifting of the pole as cause of the ice 
ages in a paper: Strandlinje-studier in Archiv for Mathematik og Naturvidenskab 
Kristiania, 1890-91, T. 9-10. 


126 THE JOURNAL OF GEOLOGY. 


needs be impossible farther out than at the innermost fjord heads 
The greatest distance between the heads of any two neighboring 
fjords on the whole Norwegian coast is only about 60 kilometers 
(less than 40 miles), and an ice stream driven out over this neck 
between Sognefjord and Nordfjord could not by any means reach 
a height of 510 meters at the isles in the mouth of Sognefjord, 
where we find glacial grooves and foreign boulders 1,760 meters, 
5,700 feet above the fjord bottom. With only 20 to 30 kilometers 
to discharging outlets on each side, its thickness would ever be 
small. The fact must be kept in view that the inland ice behind, 
from which the ice stream flowed, had only a very inconsidera- 
ble breadth. The distance from the fjord heads to the present 
watershed is nowhere more than 30 kilometers, and the want of 
boulders transported from the country more to the east proves 
that the ice-shed, the glacial divide at the glacial period, could 
not have been situated far from the watershed. Now a névé less 
than 30 kilometers broad could never have pushed a continuous 
margin beyond a close set row of deep fjords. As we now in 
southern Norway actually find the whole west coast, except the 
highest points, very strongly glaciated, we are forced to admit 
that the only state of things in which the ice could have advanced 
so far west is to be found in a country where depressions, of a 
volume in any degree comparable with the present fjord system, 
are wanting. We are obliged to ascribe the formation of our 
fjords to Quaternary forces—that is, glacial erosion. 

We know that boulders from the Kristiania fjord are found 
in the till as far away as North Netherlands and at Holderness, 
in England. We further know that the east-going ice flow in 
Scotland was turned back in Sutherland and that Orkney and 
Shetland were glaciated from the east, z. ¢., from Norway. A 
continuous inland ice could not have grown gradually across the 
deep Norwegian channel, which encircles southern Norway, the 
deep sea basin reaching 900 meters. As in the case of the fjords, 
we must also conclude that this fjord-like basin (which indeed 
does not reach the depth of some of the fjords) did not exist in 
preglacial times, but owes its origin to the ice stream that flowed 


GLACIAL SUCCESSION IN NORIWAY. 127 


outwards in it, following the line of least resistance for the ice 
overflow in central Scandinavia. This only need be 1,500 
meters thick to be able to erode the bottom when the maximum 
erosion was in progress. This ice stream turned round the Naze 
and left its bottom moraine also on the southwestern Norwegian 
coastland, e. g., on Jaederen, where boulders from the Kristiania 
territory are very numerous. 

While the extreme eastern margin of the first great inland ice, 
as demonstrated by the extension of the boulder clay, reached 
to Kiew and Petschora, we must thus place the western margin 
at the steep slope to the Norway deep in the North Atlantic 
Ocean. But we have reason to think that it did not remain there 
for a very long time. As the weight of the ice increased the 
land was obliged to szk below it. This follows not only from 
the general physics of the earth’s crust as demonstrated by O. 
Fisher, but can also be directly deduced from facts observed in 
all former glaciated countries. Invariably when there comes an 
inland ice there follows a depression; with the melting of it there 
is everywhere a re-upheaval; and everywhere the amplitude of 
the crust motion is in close accord with the thickness of the ice 
sheet.t Under the great first inland ice, Norway sank and there- 
with came a raising of the snow line in relation to the ice surface 
and an aggression on the ice from the rising sea. Under these 
circumstances the ice margin was forced back, and many things 
indicate that it at length took up its position at ab ut the present 
coast line and paused there while the great terminal glaciers 
flowed down preglacial depressions and made new ones and 
scooped out, by long continued action, our grand fjords. Judg- 
ing from their form and great dimensions, this erosion took place 
under very constant circumstances. The ice must have kept its 
place for a very long period constituting, in all probability, the 
greater part of the first great ice age. It might be objected that 
when the ice receded by the sinking of the land, the crust 
upheaval must have followed immediately. As the sea with its 


«This I have followed out from the known glaciated countries in my Strandlinje- 
studier, but cannot in this place re-state it more fully. 


128 LAE JOURNAL ZOR, GUOLOGNE 


greater specific gravity in a great degree replaced the melting ice 
margin, the consequence appears to have been that the land finally 
lost in height perhaps as much as 200 to 400 meters. We shall find 
analogous phenomena in other glaciated countries. 

The thickness of the inland ice in Norway at this time we are 
able to estimate by the upper limit of foreign boulders and by 
the lower limit of the rocks on mountain summits which were 
not reached by the ice sheet. Where a great continuous scoring 
ice sheet has worked we find in Norway, as in Greenland and 
elsewhere, the smooth undulating surface lines with fresh rock 
surfaces. Higher up, above the reach of ice, we find the nanatak 
formation with peaks and cirques (botner) and with highly 
weathered rocks and mighty talus and other debris. By such 
limits we can approximately determine that the maximum height 
-of the ice sheet in southern Norway was below 2000 meters, in 
northern Norway about 1200 to 1500 meters, these being reckoned 
from the present sea level. As the mean height of the Norwe- 
gian highland may be estimated at 800 to 1oco meters, and 
as only central Norway reaches more than 1200 meters, we 
get an ice sheet which, near its axis, will measure only about 
800 to 1000 meters. To this thickness of the ice the depres- 
sion of the land answers very well according to O. Fisher's 
theory. 
The first great Quaternary glaciation of Norway was followed 
by other great climatic changes. To get a more handy term- 
inology than the common periphrastic nomenclature, I have pro- 
posed, for the most pronounced periods, the names proteroglacial 
for the earlier great ice age as distinguished from the well-known 
last great glaciation that followed—the dewteroglacial. I have 
chosen and press for acceptance at the Congress terms implying 
the first and the second of fwo periods because these two glacia- 
tions seem to be demonstrable for all glaciated countries. The 
names cannot well be misunderstood, and if, perchance, as some 
American and German geologists assume, a third separate glacia- 
tion can be proved, it will be easy to give it a mame apart. So 
far we can only distinguish in Norway preglacial, proteroglacial, 


GLACIAL SUCCESSION IN NORWAY. 129 


interglacial, deuteroglacial, and postglacial periods, all very 
clearly denoted by these names. | : 

The proteroglacial period came at last to an end. The ice 
retired very much; an interglacial period followed. Of this 
warmer period we know very few certain traces in Norway. 
Almost every deposit referable to it has been swept out by the last 
—the deuteroglacial—ice sheet at least in the parts best studied. 
At Jaederen we certainly have some layers of gravel and sand 
between the undermost bottom moraine carrying boulders from 
the Kristiania territory, and the uppermost one bearing boulders 
from the mountains close by on the east, but these layers do not 
contain, as far as known, any fossils giving information about 
the climate, and it may very probably be that they must be 
referred to the retiring proteroglacial or the advancing deuter- 
oglacial ice. | | 

The part of the proteroglacial country which was not covered 
by the deuteroglacial ice sheet or sea—and which, therefore, might 
have retained interglacial deposits—is very poor in loose matter 
and it has, as yet, not been possibile to distinguish any interglacial 
debris. In the center of the country at Vage, near the highest 
mountains in Norway, there was some years ago found in river 
gravel a molar of the mammoth. It may now be said, that this 
tooth is certainly neither postglacial, protero- nor deutero- 
glacial, as the tract in these periods was quite ice-covered. There 
remains the assumption that it is preglacial or interglacial, and as 
it is not very probable that this molar has remained unmolested 
through the very long first glaciation by which the whole country 
was deeply eroded, it is perhaps permissible to take it for inter-- 
glacial. In this case we may conclude that the country in inter- 
glacial time was covered with forest up to the highest plateaus ; 
and, therefore, the proteroglacial inland ice was entirely gone. 

It is, however, more reliable to seek for support by a compari- 
son with neighboring countries. The peats in parts of Denmark 
not deuteroglaciated show an arctic flora with Dryas, Salix polarts, 
herbacea, and reticulata, which followed the great retreating protero- 
glacial ice sheet, and this was superseded by a vegetation char- 


130 THE JOURNAL OF GEOLOGY. 


acterized by Populus tremula, and this again by a Pinus sylvestris 
flora. 

Above the layer with Pinus comes a new one with oak and 
finally the surface stratum with recent forest trees. Now in the 
peats of deuteroglaciated Norway and Sweden we always find the 
oak layer on the bottom (with a layer of pine and birch above), 
which shows, without doubt, that the preceding vegetations in 
Denmark and Scania must be interglacial. To judge from the 
aspen and pine forests it might be concluded that the inter- 
glacial climate in Scandinavia was somewhat colder than the 
present, but the melting of the ice may have required a higher 
temperature and the fossils from layers between the two 
bottom moraines in the Baltic countries bear a rather southern 
stamp. 

Wecome to more reliable ground when we advance to the last 
great glaciation in the deuteroglacial period. Again the snow 
gathered on the high mountain plateaus, again glaciers pushed 
forward towards the lower ground accompanied bya severe climate. 
But the glaciers this time were met almost at the watershed by the 
deep proteroglacial fjords which necessarily must put an end to 
their advance westward. The continuous western ice margin 
could not reach beyond the fjord heads. To the east, however, 
the way was free for the growing inland ice. The consequence 
of this was that the zce sheet divide crept eastwards and reached 
a line up to 130 kilometers southeast of the land watershed. 
Here at last the resistance to the glacier motion was alike on 
both sides of it. We therefore find the boulders in deuteroglacial time 
—in contrast to the distribution in proteroglacial time—¢rans- 
ported across the watershed from lower ground in southeastern central 
parts up hundreds of meters to the divide and borne on as far 
west as the deuteroglacial ice and its icebergs went. 

To the west we find the ice margin determinated by the fjords, 
to the east it pushed forward out to the coast line by Skagerak. 
We find its margin, as in the case of the deuteroglacial ice in North 
America, marked by a long terminal moraine—raerne—from 
Arendal to the Kristiania fjord and thence to southeastern Sweden. 


GLACIAL SUCCESSION IN NORWAY. 131 


Also in Finland we find a terminal moraine near the south coast. 
But through this terminal moraine there crept out a very long 
Baltic ice tongue which reached down to Brandenburg and the 
eastern part of Schleswic. Behind the terminal moraine in Norway 
we find a series of lakes eroded, here as elsewhere, near the ice 
margin, but these lakes are rather small and have no relation to 
the present valleys behind. It is therefore reasonable to suppose 
that the inland ice did not have any very considerable thickness 
here when it reached this extreme limit and also that the valleys 
were not yet fully developed. 

As in proteroglacial time, the country again sank under the 
ice weight and again the ice sheet retreated with the relative 
raising of the snowline, and advance of the sea. The retreat is near 
Kristiania fjord marked by three or four discontinuous moraine 
lines with, in places, rather large lakes behind (Oiern, Tyrifjord, 
Norsj6). But in Norway—as in America—a final position was 
not reached before the great marginal glacier was settled in what 
was to become a fine row of great lake basins: Solér (filled up), 
Mjésen, Randsfjord, Sperillen, Kréderen, etc. This most constant 
phase of the deuteroglacial time deserves a particular name. I 
have called it the Epzglacial epoch, as it closes the great glacial 
series. It is parallel to the American Champlain epoch, but as 
American geologists (Dana especially) regard the Champlain 
epoch as postglacial, I have not ventured to accept the name. 

In southeastern Norway we find the terminal glaciers ending 
in the greatest lake basins in the country; in western and northern 
Norway the glaciers were, as above explained, stopped by the 
fjord heads. But here we also find that the glacier ends every- 
where once occupied smaller but yet deep lakes, with bottoms often 
below the sea level, just behind the fjord heads. When we in 
Norway have more than 100 such lakes cut in the rock just where 
the glaciers terminated, I cannot see how it is possible to evade 
the conclusion that these lakes must be of glacial origin. It will 
not do to suppose that this coincidence of so many lakes and 
glacier ends is the merest accident. The relation must needs be 
genetic. The form ofthe lakes is the typical trough with a longi- 


ie THE JOURNAL OF WG EOLOGYV, 


tudinal section in the best accordance with the probable distribu- 
tion of the erosive power in a glacier. 

The rock matter which was scooped out by the epiglacial 
glaciers was deposited partially as terminal moraines, but mostly 
as terraces in the fjords. We therefore now find the epiglacial 
lakes everywhere separated from the fjord heads by some kilo- 
meters of terrace land. These great upper terraces mark the 
level of the epiglacial sea. Their height differs very much in 
the different districts, and it was first by the study of the corre- 
sponding ancient sea beaches that I was able to find the correla- 
tion between them. In western and northern Norway, these 
ancient sea margins are very distinctly marked, often in the 
living rock. As might be expected, in accordance with the 
theory of isostasy of the earth’s crust, these lines are now raised 
towards the former center of the ice sheet, from which the max- 
imum ice load was taken away. Nearest this point the epigla- 
cial sea beach and terraces now reach 200 meters above the sea, 
with a gradual fall towards the outer coast, where their height 
is only some 20 meters or less. The gradient in the fall is much 
greater than in Lake Agassiz, reaching 1.2 meters (4’) per kilo- 
meter, against 0.10 meters (20"), but it is clearly the same 
cause that has been at work in both cases. 

The height of the deuteroglacial ice sheets seems to have 
been almost the same as in the proteroglacial—less than 2,000 
meters maximum above the present sea level. 

The epiglacial terraces contain in some places banks of 
shells with quite an arctic aspect. The deeper clay has Leda 
artica as its leading fossil. The climate must have been very 
like that at present in South Greenland, and the topographical 
physiognomy must also have been very much the same, with a par- 
tially alpine foreland (which constituted nunatak forms as in the 
proteroglaciated epoch), and with glaciers at the heads of the 
fjords, with great clay bars or deltas before them, and with 
small floating icebergs to score out the strandlinjer—the sea 
beaches in the rock. 

It is altogether probable that a meteorological map of Nor- 


GLACIAL SUCCESSION IN NORWAY. 133 


way in epiglacial time was very like a modern map of Green- 
land. The isotherm of o°C. for the year must have followed the 
southern coast perhaps as far up as to the polar circle. The 
lower isotherms must have enclosed a pronounced minimum to 
the east of the ice shed, where certainly — 20°C. must have 
reigned.*_ While the difference from the present mean tempera- 
ture at the coast was only 5 to 6° C., the difference near the pole 
of maximum cold must have been 15°C. at least. This great 
difference, which is a necessary consequence of the contrast 
between coast climate and the pronounced continental climate 
over the east side of the great ice field, is as yet not sufficiently 
noted by the students of glacial time. An exact consideration 
of the distribution of the meteorological elements above the 
inland ices will give the solution of many glacial problems. I[ 
shall here only remark that the snowfall in this continental 
region must have been almost imperceptible as in winter in 
Siberia now—and likewise the melting. Now, the power which 
keeps the glacier in motion is ever the surplus of snowfall. The 
whole continental side of the inland ice must thus be kept in quite 
a passive motion, be pushed as a rather thin ice plate out to the 
margin by the press from the greater snowfall on inside ice nearer 
the ice shed and the coast. The reliable measures of the ice 
sheet in the Baltic show really very small dimensions—less than 
200 meters—thus it will become intelligible why the greater ice 
masses to the west can keep the ice divide four to six times nearer 
the western margin. An ice plate of about 100 meters or less 
must be impotent to erode. The bottom moraine from the more 
powerful inner part must be gradually built up de/ow the outer 
thin marginal ice sheet. On the continental side we will have 
formed a regular boulder-clay or thick bottom moraine outside 
an area where denudation in the form of broad shallow basins or 
plains will still take place—all this against the deep rock basins 
with terminal moraines and terraces before them, on the coast 
side. The snowfall here will be very great. The surplus ice 


«Cf. H. MoHn’s meteorological map of Greenland in Wissenschaftliche Ergebnisse, 
von Dr. NANSEN’s, Durchquerung von Groenland, Gotha, 1892. 


134 THE JOURNAL OF GEOLOGY. 


will be carried with considerable speed by steep glaciers to the 
sea; the localized erosion will be very energetic; and we will 
get the fiords and the lakes—while the eroded matter will only 
be deposited defore the glaciers as terminal moraines and terraces. 

As the ice shed will be rather near the coastward margin of 
the inland ice, it follows that it is for a great part the enormous 
snowfall on the great western glacier’s own surface which 1s to be 
transported. Hence these glaciers can follow more irregular 
lines from the first, only deepening and widening the preéxist- 
ing valleys, and so we get the complicated fjord systems; while, 
on the continental side, where a more uniform vis a tergo pushes 
the ice plate forward, the eroded depressions must be more regu- 
lar. It is quite necessary to keep in view this great contrast 
between erosion and deposition on the part of the continental 
and the coast sides of the great ice sheets, respectively, in order 
to be able to understand many of the complicated glacial phe- 
nomena. 

We have seen that the deuteroglacial and especially the 
epiglacial inland ice had its ice shed far to the east from the 
watershed. Across this divide the ice must move and with 
somewhat accelerated speed in the narrow defiles. There must 
here originate passes or gaps (skar in Norwegian) across the 
watershed. Of these, we really have very many in Norway with 
a development in distinct relation to the distance between the 
ice-shed and the watershed and to the greatness of the epiglacial 
lakes and valleys on both sides. In not a few we have lakes 
with outlets on either side. 

When the ice stream through such a gap came out to the 
western edge of the high plateau, there resulted a sort of ice 
cascade, which, like a waterfall, receded with rather great speed. 
These receding icefalls evidently gave origin to most of our 
Jfjora-valleys, sack-valleys, culs de sac interior to the fjord heads. 
Also these must generally be of deuteroglacial origin, as only 
then the ice flowed in great streams across the watershed. 

The epiglacial stage of the deuteroglacial period must have 
had a very abrupt termination. The glaciers retired from the 


GLACIAL SUCCESSION IN NORWAY. 135 


epiglacial lakes without filling them up in any considerable 
degree. The ice melted so speedily away, and the crust swelled 
up so fast, that the deposits of the rivers just below the epi- 
glacial terrace level are very small. This could only occur with 
a climate more genial than the present in which an existing 
glacier as great as the epiglacial land ice would certainly assert 
itself with success. 

We must suppose a considerable uplift of the snow line in 
this time which followed the epiglacial period, and which I shall 
call the Boreal period. Such a genial climate in early post- 
glacial time we are forced to assume also on biological reasons. 
On the warm valley sides in the western interior fjords, we find 
many plants which can only prosper in a temperature more 
than 2°C. higher than now prevails in the intervening tract 
across which they must necessarily have immigrated. On the 
southwestern coast flourished a vegetation almost like the Irish 
coast flora, but separated from its main habitat by a temperature 
perhaps 4° C. lower in January than it will bear. These Boreal and 
Atlantic plants can only have spread to their isolated places in 
Norway in a climate some 3° C. warmer than the present. That 
this warmer time did occur in early post-glacial time is again 
proved by the stratification in the peats, where the plants most 
susceptible of cold (ash, oak, etc.) are found in the deepest 
layer or rather on the bottom itself—this also in places on the 
coast and in the mountains where now no forest tree grows. 

These 3-4° C. recorded by the vegetation would certainly 
have raised the snow line, which now is 1200 to 1800 meters above 
the sea in Norway, above almost the whole epiglacial ice sheet, 
which nowhere attained 2000 meters. The great inland ice must 
then have become a dead glacier, and must have melted rapidly, 
especially from the margins. The last remnants of it might be 
supposed to have been situated near its maximum elevation, 2. é., 
near the ice shed. This lay, as explained above, in deuterogla- 
cial time at some distance to the southeast of the land watershed, 
as the many boulders in the upper eastern valleys which were 
transported upwards prove. The ice remnant is then to be 


136 THE JOURNAL OF GEOLOGY. 


sought for as far as 100 kilometers to the east and south of the 
watershed. This southern position was moreover accentuated by 
meteorological facts. The western moist winds are intercepted 
by the broad western alpine foreland and the high land near the 
watershed, while the low country at the southeast would give the 
moist winds free access to the southern glacier side. The country 
close to the watershed on the southeast now gets almost all its 
humidity from the southeast winds, but these would, in early post- 
glacial time, be barred by the inland ice, which in this way would 
come to have a very dry north side, in contrast to a very moist 
south side. This would draw the last inland ice out to the south- 
east edge of the mountain plateau to a point not far above the 
great epiglacial lakes in southern Norway. 

_ But the melting of the inland ice did not go on uninter- 
ruptedly.. When the land had risen more than half the post- 
glacial uplift, and when, presumably, the ice was more than half 
gone, a new deterioration of the climate commenced. It is pos- 
sible it did not get worse than the present, but it was enough to 
stop the melting of the inland ice, which again arose above the 
snow line. The ice again assumed the character of a living gla- 
cier, and kept its position unaltered for a long time. Under the 
pressure of this constant ice load the land again was kept at a con- 
stant level. We find, especially in northern Norway, a new strand- 
linje (sea beach), occurring at about 4o per cent. of the epiglacial 
and great terraces, built up with a fauna quite like the modern. 
This new marked phase in postglacial time I have called the sué- 
glacial period, denoting its half glacial condition. In Sweden this 
epoch is also marked by a very distinct beach line, but in Scania 
and Gothland this low raised beach in places is built upon peat, 
which shows that the uplift of land in the Boreal period did 
exceed that in the following. For this reason, the Swedish geol- 
ogists speak of the post-glacial depression. The term post-glacial 
for this general phase is very unfortunate. It must necessarily 
literally denote all the time after the deuteroglacial-epiglacial 
period, for which time we have no other name. And as the 
constant level in Norway only represents a single phase in the 


— 


GLACTAL SUCCESSION IN NORWAY. Tiny 


general post-glacial upheaval, and as the depression in southern 
Sweden may be a quite local, peripheric phenomenon attached 
to the Baltic, I must insist upon the more significant, yet neutral, 
form swbglacial period for the age of the lower beach line. 

The inland ice was then, as explained, reduced to a zone 
(about 50 kilometers broad) across the middle of the eastern val- 
leys. This fact must have a curious consequence in the fact that 
these valleys must have been dammed up by the ice and filled with 
lakes whose outlets ran west and north through the gaps in the 
watershed. These glacial lakes have actually left very distinct 
marks in the greatest eastern valleys in Norway, Gudbrandsdal 
and Oesterdal. We not only find in their upper tracts enormous 
terraces of material brought by the glacier from the south, terraces 
without any parallel on the other side of the watershed, but we 
also find here very fine beach lines—se¢fer—partially cut in the 
rock, corresponding in height with the terraces and with the 
draining gaps, 620", 660" respectively—dquite like the famous 
Parallel roads of Lochaber, but very much more extensive. 
From these ice-dammed subglacial lakes there flowed great rivers 
across the present watershed filling up with their heavy sediment 
many of the epiglacial lakes on the northwestern coast, and 
building great subglacial clay terraces at the level of the lower 
ancient sea beach. 

The erosion of the marginal glaciers has set its mark also in 
the subglacial time in some inland lakes as Storsj6 and Sensjé, 
in Oesterdalen, Mésvatn and Totak, in Telemarken which have 
their greatest depth in the upper part and terminal moraines at 
the present upper end of the lakes. 

So far as I can see the subglacial period also prevailed in North 
America, without receiving yet, however, due attention from 
glacial students. I cannot here deal with all the raised beaches 
in the east formed by the sea and by the lakes which naturally 
can be referred to this period, but I shall use the occasion to 
point out that the apparently insoluble difficulty in harmonizing 
archeological and biologicai facts with the geological data con- 
nected with the ancient ‘“Quaternary”’ lakes in the Great Basin 


138 THE JOURNAL OF GEOLOGY. 


will immediately vanish when the two great humid periods are 
regarded not as proteroglacial and as deuteroglacial, but as 
deuteroglacial and subglacial or—what I think is more probable— 
as correlate with the two Norwegian post-glacial warm periods 
(before and after the subglacial), the climatic changes caused by 
a shifting of the pole westwards, which alone is able to account 
for the late glaciation of the Cordilleras in Atlantic post-glacial. 

At last also the subglacial remainder of the inland ice com- 
menced to melt away in the warm subboreal period. The coun- 
try rose farther above the sea, and finally, by some intermediate 
steps, attained its present position. The modern sea beach shows 
everywhere so great a development, and is so sharply built, that 
all alleged displacement in historical times must be received with 
the greatest distrust. We have, notwithstanding all such rela- 
tions, full reason to maintain that the seashore since the ice left 
has remained practically unchanged, as also the climate in histor- 
ical time. We have reached the constant recent period in the most 
rigorous sense, and therewith conclude our synopsis of the Qua- 
ternary history of Norway. 

There is, however, yet a problem of capital interest, which I 
cannot quite pass even in this short account. It is the question, 
When did man appear in geological history? The evidence 
given in Norway is, however, not very direct. We have seen 
that all traces of preglacial life were swept away, except the 
littoral find at great depth at Storeggen. We have also seen 
that the traces of interglacial life are very doubtful, and that 
we were obliged to go to Denmark to get better information 
about interglacial time. We have found that the Arctic flora 
here (with the reindeer) which flourished upon the protero- 
glacial bottom moraine, was superseded by the aspen vegeta- 
tion (with elk) when the reindeer had already disappeared (J. 
Steenstrup). Now we know that in central Europe paleolithic 
man was contemporaneous with the reindeer, which will date 
this reindeer period back to the close of the proteroglacial time, 
and probably yet higher up. But in Denmark, it is only with the 
next vegetation, with Pinus sylvestris, that the first traces of man 


GLACIAL SUCCESSION IN NORWAY. 139 


appear, represented by the well-known refuse heaps, the Loken 
moddinger, where, with shells and bones of Bos primigenius and 
Alca impennis, are found many rude instruments of horn, bone, or 
stone. This culture, which did not know any other domesticated 
animal than the dog, is by some archeologists called mesolithic. 
Kokken moéddinger and implements of the same type, “He coast 
jinds, are only discovered in non-deuteroglaciated places of Den- 
mark and Sweden, which fact alone goes far to prove the 
assumption that the Pinus sylvestris period really is interglacial, 
as I have advocated above. And the molluscs in the refuse 
heaps on the northern shores of the Danish isles are quite the 
same as in the (upper) Cygrina-clay on the southern shores, 
which overlies the proteroglacial moraine, and is here generally 
ploughed out by the rather feeble margin of the deuteroglacial 
Baltic ice tongue. This interglacial layer contains often a stratum 
with fresh water molluscs and in this supramarine deposit there 
was found in Langeland shells of Cardium edule and Nassa retic- 
ulata, in which I cannot but see a rudimentary kékken modding 
and a proof for the interglacial age of this mesolithic culture. 
From Norway we have only a few finds of implements of this 
type, as might be expected, because the habitable coast was so 
greatly depressed and covered in the following deuteroglacial 
period. But it is reasonable to suppose that it also was inhabited 
by a population akin to the Danish. When the latest ice sheet 
pushed forward to the great mostly-submarine terminal moraine, 
the retreat of this population on the western foreland was inter- 
cepted, and interglacial man was obliged to adjust his mode of 
life somehow to Esquimau fashion. But there is no reason to 
think him quite exterminated here on the shore of the life-giving 
Atlantic. And anthropologic studies have indeed proved that 
on the western margin, just so far east as the deuteroglacial ice 
left land outside, there lives yet a brachycephalic population, 
while everywhere else (even in the innermost western fjords) 
dolichocephals and mesocephals are in great majority. This 
distribution of anthropological types is quite unaccountable by 
any other supposition than that the brachycephals are descend- 


140 THE JOURNAL OF GEOLOGY. 


ants of the interglacial Norwegians and that the whole deutero- 
glaciated country was peopled by Aryan dolichocephals in early 
post-glacial, boreal time. We know that these new immigrants 
had at least four domesticated animals, and were in possession of 


the art of grinding their stone implements. Can we now date the © 


appearance of neolithic man by more direct geological means? 
There are found so many flint implements in such depth in 
probable subglacial terraces in Norway that it may be taken 
for granted that the country was populated, however sparsely, up 
to and beyond the polar circle in subglacial time. In Sweden 
polished implements have been discovered in the peat layers 
below the subglacial beach, so it will perhaps be reasonable to 
refer the first appearance of neolithic man also on geological 
dates to the genial Boreal period between epiglacial and sub- 
glacial time. Approaching our own culture, we find that the 
country in the dvonze age was still depressed. In Smalenene, to 
the east of Kristianiafjord, are observed about 150 rock sculp- 
tures from the bronze age which are situated at about 22 to 25 
meters above the sea; none at lower levels. As these sculptures 
almost always are made along a shore, we are justified in sup- 
posing that more than ten per cent. of the land yet was unfinished 
in early bronze age. From early zvon age we have barrows quite 
near the present constant sea level, so we may assume that the 
recent geological period coincides with the iron age and histor- 
ical time. 

If the theory of ice depression is correct, there must, even 
in the bronze age, have existed a remnant of the inland ice, 
which, as explained before, must be sought for across the mid- 
dle of eastern valleys. In this zone we could not expect to find 
implements from the stone age or bronze age. There has as 
yet been found only four stone hatchets in all the districts near 
the former ice shed, against many hundred stone implements in 
the districts on both sides of the same valleys, and these per- 
forated hatchets have been in use far down in metallic time. 

The ice zone must have stopped the immigration as the inland 
ice of Greenland does now. This is the reason together with the 


ee 


De 


enrerctisk 


GLACIAL SUCCESSION IN NORWAY. — 141 


depression of the coast land why neolithic man did not go farther 
up in Sweden than 61” northeast, while the Norwegian coast was 
free all along, and permitted his advance up to 70°. Another 
consequence is that the northern part of the long valleys in 
southeastern Norway must get its first population from the west 
coast. This is also proved to be the case, not only by the exist- 
ence of a well-marked anthropological boundary across these 
continuous valleys, but also by a singular contrast in dialects and 
traditions. Reversedly, this signifies that the present Scandi- 
navian race really was the first post-glacial occupant of the coun- 
try. In the administrative divisions we find traces of the old ice 
barrier as far down as only a century ago. It is thus possible to 
follow the effect of the ancient land ice in Norway down to our 
own day. 

In closing this hasty summary of the Quaternary history of 
Norway I cannot quite omit the doubtful question about the abso- 
lute chronology. We have seen that in the bronze age which the 
archeologists are able to date in Scandinavia from 1700 to 500 B.C., 
more than ten per cent. of the post-glacial upheaval was not yet 
accomplished. As the upheaval has not been uninterrupted, we 
cannot directly conclude that the whole elevation has had a dura- 
tion of about 30,000 years. The long time from early iron age 
in which the shore line has been constant enters into our standard. 
But we can draw a more reliable comparison between the ter- 
races from the different periods, when we take the greater eroding 
power of the old inland ice and its greater glaciers in due con- 
sideration. I cannot here specify my calculations, but will say 
that I regard myself-as on the safe side when I compute the 
time for forming the subglacial terraces and beaches to not more 
than double the last constant period, which may be reckoned at 
2,000 years. For these two constant post-glacial periods together 
we thus get about 5,000to6,000 years. The relatively small terrace 
deposits from the remainder of post-glacial time cannot by any 
means give more than half this value. We may, therefore, on 
this, as I think, very reliable estimate, calculate the whole post- 
glacial time to be 7,000 to 9,000 years. To about the same numbers 


142 THE JOURNAL OF GEOLOGY, 


I have come by calculating from the mean depth of neolithic 
finds in Norwegian peats, but this computation has not quite so 
much importance, though the fact that the generally adopted 
archeological chronology agrees as well with geological estimates 
certainly has some weight. 

I shall recall the fact that calculations on the length of post- 
glacial time based on the receding Niagara, St. Anthony Falls, or 
the Michigan lake shore, on boulder pedestals in Scotland, the 
denudation of the Somme, the Plum creek, or the Raccoon valley, 
deposition of the Tiniére or the Rhone, etc., delta, the thickness of 
glacial clay in New Hampshire and in Sweden, the rate of growth 
of peat in North America and Ireland, the atmospheric waste of the 
Parallel roads in Lochaber, the depth of some ancient neolithic 
finds, that all these give numbers of about the same value, 5,000 to 
12,000 years. Doubtful as some of these chronometers may be, 
all fair chances are against any supposition which differs in any 
considerable degree from those of about “urty independent esti- 
mates I have got together. With full regard to a legitimate cal- 
culation of probabilities, it may be predicated that the number of 
7,000 to 10,000 years is as nearly an exact estimate of the dura- 
tion of post-glacial time as can ever be expected. 

It is now tempting to try a comparison between the subglacial 
and the epiglacial terraces and lakes in Norway. When the 
much greater eroding force of the epiglacial glaciers is properly 
reduced, I do not think it can be very much at variance with the 
truth to compute the epiglacial period to be between five and 
ten times the duration of the subglacial, the smaller number being 
somewhat more probable. We would then get 70,000 Zo 20,000 
years for the epiglacial period and perhaps 15,000 to 25,000 for the 
whole deuteroglacial time. For the interglacial period, the Norwe- 
gian geology cannot as yet give any reliable measure but the depth 
of the aspen and pine layers in the Danish peats as compared with 
the post-glacial oak and birch layers does answer very well to the 
American estimates of one and one-half to two times the duration 
of post-glacial time—let us take about 15,000 years. We may 
next compare the proteroglacial fjords with the epiglacial lakes 


GLACIAL SUCCESSION IN NORWAY. 143 


and may by these means get some idea as to the length of the 
first great ice age. The farther we go from our own time the 
more wholly conjectural will our numbers become, of course. 
But as other more reliable measures as yet are wanting, I shall 
venture a first approximation, calculating the time in which the 
enormous proteroglacial marginal glaciers eroded our fjords, as five 
to ten times the epiglacial time in which our great epiglacial 
lakes were scooped out—the higher estimate in this case being 
somewhat more probable. This would perhaps make 700,000 ¢0 
Z50,000 years for the whole proteroglacial period, t.e., about five 
times the duration of the deuteroglacial time—a relation which, 
as far as I see, is in very good accordance with the general 
quantitative difference between the effects of the first and second 
great glaciations.. This will give for the whole Quaternary-post- 
tertiary time about 140,000—200,000 years. 

I see very well how precarious such computations may seem, 
especially as I here cannot give the detailed calculations—but I 
do not think it possible that any of these have given numbers 
five times too great or small. Under these circumstances 
they must be taken for a very good geological approximation. 
By getting parallel estimates from other glaciated countries, it 
will appear, I think, that we will have, on wholly geological ground, 
more positive and reliable data for the Quaternary chronology, 
than those derived from astronomical speculations. 

I add for greater ease in comparison my reading of the 
Quaternary history of Norway in a tabular form. 

Awnpr. M. HAnseEn. 


THE JOURNAL OF GEOLOGY. 


144 


‘NASNVH ‘W YaNV 


‘C6gI ‘IsnonYy ‘WAGaAL] ‘SAVN 


“OUIT} [BOTIO}SI 


‘2b | fade uoiy ‘Pv. suasaid ayy, ‘by | ‘yuesaid ayy ‘bh | ‘yuasordayy, ‘bh | yuosaidoyy, *y | “yuasoid ayy, *F ‘qu0y) *h | “yUR.ay “PY 
*yeavoydn *syead 943 Ul ‘ 
ayy Jo ‘jod o1je | ourg ~‘*SUIIO) Wa “1ay3ry *Sa0u1 ‘juasaid ayy | “ABME ic | ‘[e2roq 
ase ozuoig *€ | -yynos ouog ‘€ | wey MauOGg “tf | -193 [[eEuUSg *f ‘mou SY “Ef 0} suisny *£ sunley “t -qng °€ 
“6-4 *SO0B119} "Iajyag ARM *yoeaq yusIO *sAa][eA U1 *[e1oe[s\sog 
‘ue pueyur {30d ob | -10N [e1}UD9 | -ue ("30d OF) | ~sea 9Y}SSOIDe | *[eIDels 
€-2 | DYIT[OIN *z *MOU SW ‘Zz ‘mou SW ‘2 | je Sodvlay ‘2 | UI Saxe] ‘% | JamopayiyVW ‘2 | Jdaoxa qu0y *z -qns ‘z 
*so0el 
‘uOeIST UWI *(yse *IOWIIeEM # ‘saoe1 | -19} [e1oedida *ATpt *A[p! 
OYIT[OON ‘2 | ‘YeO) [easog ‘zr | ‘dQ .£ ogy “1 | -19} [[BUTG “Z| UT synooATy.T | -der Sursry ‘1 -derdun[ayl ‘I | *jeaiog ‘1 
*sAQT[BA 5 
yeVS “paysie} “speoy p1oy at} 
-eM ay} ye sdey puryaq soxe| 
“(Kel *so0e119} | “SPIO ay} Jesu “yoveq yus1d | ay} ur siaroR[s | “eles 
Sz |*oz (Avy ‘yuo 5 Q : o S era ig G *Te1oela 
“G5 lon 2 epa]) OV “2 | sod oy) ueys auleUu ysiP *@ | sayxey years) ‘z | -ue ssddyQ ‘2 | [eurusioy, ‘2 dq :z | [et A einaer 
TOMO] ‘d) .S-S*% ERED 
: ‘one ayy ‘souleioul | 0194} Teauyua | ‘andu0} on[eg 
punoiwmranip | purysq saxey| | -serd oy} mojeq | oureiour [euru 
todd ‘aureiou | 93e1pauriajzur | ‘py oSz ynoqe | -19}‘speay proy | *yoody 
[eulwdiay “rt | puesoyxel-eyrt | 0} suryurg ‘2 | 9430}SMOID) “I -By ‘1 
: sa[As snutg ) . 
Kem | .3rurrad sog C 
-ION ur ‘ydaoh eA : 3 (é)usrapoe f f 5 
oz-S1 -Yoeig U19}Sa Ay WEED (lo Mou UeYy 19 | ye siakey pues Se0T0F | (3) yuasaad ayy, (g) au0N ‘je1oe[ 319} UT 
‘ra3urppour uay | SUINdog “1a S “UHEMSIUINIV | yeipousrazuyz | }49Se1d eT % 
yoy ysrued ° seAiq |, 
Iaapursy a Ont 
: *}SBOO SOM *e10yosiag 
uvoul | 343 punoze outt (g) qua | eeu uy gieu 
yuasaid ay) -eul-qns ureyd 3 . ula}sea ‘spioy 
MOTD **)_O1- : said ay3 ynoqe oneyeyen 
oS 1-001 *so081} ON, ‘OILY 19d “DO 0°F-8 | aoetsay, ‘apis “SPIOY | 0, yuasaid ayy ayy ur sio19R[d [Be 
0} 209903SI9[q | feyuaurT}U0D | ye913 YT, *z H jeuUlWday, ‘z °Z - O19}01g 
IQWIVM Jy : aaoqe ‘JA 0oF ° 
wmory 3urpurg UO suTeIOULWIOY | -suueyo urd | -% Wor] SYUIS ‘ado[s uea00 
OAS <9 J0qSOUSPU/) | -amMION ‘Z 2 I 3Y} OFSMOID) ‘I Di 
*(s1A 0001 ) EOE are 
uojein ‘ue ‘ginje1odwa *syisoda *UOISOI 1 *JaayS 99 *yood “porto, 
aed W pue eune,y Nb i d TSOTY Jo uoneAsrq YS 2] yoooy POltod 


‘"AVMUON AO ANOLSIH ANVNUALVNO AO SISTONAS 


DUAL NOMENCLATURE IN GEOLOGICAL 
CLASSIFICATION: 


At the meeting of the American Association for the Advance- 
ment of Science, at Rochester, in 1892, while discussing a paper 
of Professor James Hall, read by Mr. Merrill, on the classifica- 
tion of the Devonian rocks in eastern New York, I ventured to 
express the opinion that the time was ripe for the recognition of 
the duality of the group of facts which geologists attempt to 
classify in what we call the geological column or scale of 
formations. 

Since that meeting, Mr. Darton has published a paper? restat- 
ing and commenting upon substantially the same facts reported 
by Hall and proposing a special use of the name Catskill. Still 
later papers have appeared by Professors Stephenson? and 
Prosser‘ discussing the proposition made by Mr. Darton, the 
one from the stratigraphical, the other from the paleontological 
point of view. There is also now going on the preparation of a 
revised geological map of New York state, containing the typi- 
cal paleozoic section for North America. These and other rea- 
sons have led me to think it not inopportune to ask the serious 
attention of geologists to the adoption of a dual method of 
nomenclature in the classification of the facts of historical 
geology. 

There is nothing novel in the proposition that there are both 
stratigraphical and chronological divisions in the geological 
classification, but it is only recently that practical geologists 

t Presented to the Geological Society at its meeting in Boston, December, 1893. 

? Oneonta and Chemung formation in Eastern Central New York. Am. Jour. Sci., 
III., Vol. XLV., p. 203. 

3 J. J. STEVENSON: On the Use of the Name Catskill, Am. Jour. Sci. IIJ., XLVI., 
330. 

4. S. PRossER: The Upper Hamilton and Portage Stages of Central and Eastern 
New York, Am. Jour. Sci., III., XLVL., p. 212. 

145 


146 TTL iO OKINAVET OL AG 19 OL, O\GNE 


have seen the importance of classifying /erranes and periods sepa- 
rately. 

James D. Dana," in 1855, set forth, with great clearness, the 
importance of the chronological classification of rocks, and in 
his manual? all geologists have been made familiar with the 
meaning of a chronological classification of stratified rocks, but 
the classification is a classification of rock strata, and the time- 
divisions are those determined by the strata, so that but one 
nomenclature has been needed or used. 

The International Congress of Geologists was the first to 
distinctly formulate a dual method of classification, but here, 
too, it was only two ways of classifying one set of facts that 
was proposed. The divisions of the scale have been identical 
and in the terms of strata. The Congress was organized for the 
purpose of unifying nomenclature, but one of the most impor- 
tant results of the Congress has been the discovery that uni- 
formity, in the sense first proposed, is not practicable. 

In advocating a dual nomenclature, I would carry the differ- 
entiation one step farther, and propose that we give a different 
nomenclature to the time-scale, and classify it independently from 
the terrane-scale, because the fossils by which its divisions are 
determined contain, inthemselves, the evidence of their time rela- 
tions. In an article in THE JOURNAL OF GEoLOGy3 I described 
the history of the elaboration of the system of nomenclature 
and classification now in use, and showed how the geological 
formation is the actual unit of classification in the present sys- 
tem. Having called attention to the fact that the geological 
formation and the geological period have become thoroughly 
differentiated, I remarked in closing that ‘the elaborating fur- 
ther and making more precise the geological time-scale must 
come from a direct study of the life history of organisms as 


t See Proceedings of the American Association for the Advancement of Science 
for 1855; also On American Geological History, Am. Jour. Sci., II., Vol. XXII., 
PP. 335-344- 

2 Dana: Manual of Geology, Ist edition 1863, 2d edition 1874, 3d edition 1879. 

3 The Making of the Geological Time-Scale. Jour. OF GEOL., Vol. I., pp. 180- 
196. See also Elements of the Geological Time-Scale, Vol. I., pp. 283-295, 1893. 


DUAL NOMENCLATURE. 147 


recorded in the stratigraphical formations” (p. 197). It is the 
carrying out of this thought which requires the adoption of a 
dual nomenclature in the classification. 

Perhaps the best thing that can be said in favor of such a 
proposition is, that it will enable us to record the facts of our 
science with greater precision, accuracy, and truthfulness; and 
nothing worse, I think, can be said against it than that it will 
cause confusion and difficulty in mapping and in the estimating 
of the relations and values of the old terms and system of class- 
ification, this simply because it is not the old system. Evolution 
has worked the same difficulty in the classifying of organisms, 
because, it has suggested that species are changing and not fixed 
quantities, and in the early part of this century the principle of 
identification of rocks by their fossils upset, in a similar way, 
the elaborate classification of the Wernerian school based upon 
the supposed natural sequence of particular kinds of rocks. 

Where new geology is being elaborated, the application of 
the dual method may be easily attained, and the adoption of the 
method by the United States Geological Survey ha’ therefore 
been found possible and practicable. But the greatest difficulty, 
and hence the real retardation of progress, is found in applying 
the method where standards have been established and used on 
the old basis. The New York rocks constitute, for North 
America, the standard section of Paleozoic geology. They were 
classified on the basis of unity and integrity of geological for- 
mations. 

By unity, I refer to the notion that a geological formation is 
an integral unit in the single geological stratigraphical column, 
which may be identified in distinct geographical regions by its 
fossils ; and by integrity, ] mean the notion that a formation is 
the same in its position in this column, wherever found, thicken- 
ing and thinning, and even changing somewhat in the character 
of its material from place to place, but always the same in its 
relation to other formations. 

Therefore, in discussing geology in North America, it has 
become a practice to use such terms as Oriskany, or Niagara, or 


148 THE JOURNAL OF GEOLOGY. 


Potsdam as names of geological divisions of the scale of which 
there are a definite number. These arranged in a definite order, 
according to English sequence of systems: Cambrian, Silurian, 
Devonian, and Carboniferous, etc., constitute ze standard geo- 
logical scale. 

These formations have also been called Epochs and Periods, 
and because the succession of time is continuous, the strict appli- 
cation of the method has required the filling of the whole inter- 
val, from the Cambrian to the Carboniferous, by these formations, 
except when unconformity gives marked evidence of break in 
the record. The old system requires that in all the sections, 
the lines separating the formations from one another shall coin- 
cide with the stratigraphical divisions, and progress has been 
checked by the authoritative rebuke, from those who are sup- 
posed to know, of any timid suggestion that the geology of a 
newly discovered section does not conform to the standard. 
We are already familiar with the proposition that there are such 
systems, groups and formations, on the one hand, and Ages, 
Periods and Epochs, on the other, but our whole nomenclature 
and classification is applied and used as if the divisions indicated 
by the two categories were strictly synonymous; in fact, the 
nomenclature of the International Congress went no farther 
than to propose that the names of the divisions of the one cate- 
gory, viz.: group, system, series, stage, should be applied to the 
same concrete geological facts as the corresponding names of 
the other category, era, period, epoch, age, and that these names 
of the categories should be universally used; as if, a century 
ago, zodlogists had proposed that class, order, family, genus, be 
used in a uniform manner by all naturalists. It is the essential 
idea contained in this differentiation of nomenclature, in two 
directions, which I would here emphasize and elaborate. 

When geologists consider the two scales, the time-scale and 
the formation-scale, it is found that the divisions are not synony- 
mous, but that there are two distinct sets of facts confused in 
our present nomenclature and classification. There is a geolog- 
ical time-scale, and, however we subdivide it, or however we 


DUAL NOMENCLATURE. 149 


mark or distinguish the divisions one from another, as a scale it 
is one and continuous, the parts or divisions of the scale come 
up to each other and are in aregular succession, but they cannot, 
from the nature of the scale itself, overlap or duplicate each 
other. Uniformity in nomenclature, and definite well-known 
standards and limits, and accepted means of recognizing each 
division for universal use, are essential to the perfection of this 
time-scale. In all geological literature only one name should 
be applied to each subdivision of the time scale, and there 
should be recognized for each of the grander divisions a prime 
standard, in some particular place on the earth, whose marks 
may be examined with closer and more minute discrimination as 
the science develops in precision. Further, in each continent 
we need separate standards which shall. be compared as accu- 
rately as possible with the prime standard, so that each conti- 
nent may have its typical geological time-scale, in concrete form, 
with which local formations may be corrected. 

The above applies, however, only to the time-scale; the list 
of geological formations is a totally different thing; there is no 
universal uniformity of geological formations; to attempt to 
apply a single set of names to them is always more or less to cramp 
and distort the facts. Geological formations are local affairs, and 
to restrict geological classification to a single formation scale is 
to hide-bind the progress of science. There may be as many for- 
mation scales as there are examined sections of stratified rocks, 
and we know that all the marks by which a formation may be 
defined constantly vary, so that the definition of a formation, 
small or great, is not alike for any ten miles of its extent, and 
often ten feet of extension will show clear marks of difference. 

Thus we see that there are two distinct sets of facts with 
which the geologist has to deal, and the United States Geolog- 
ical Survey has clearly recognized this truth in giving rules for 
the definition and naming of geological formations, independent 
of time relations, which are left for the more deliberate determi- 
nation of the paleontologists. It is not, however, in the new 
work so much as in the revision of old standards that the appli- 


150 LHE JOURNAL OF (GEOLOGY. 


cation of the dual system of nomenclature needs to be insisted 
upon. And when the occasion for revision of an accepted stand- 
ard, such as the geology of New York state, appears, it is more 
important to adapt the classification to the needs of the coming 
century than to preserve the imperfections of the one now clos- 
ing. It was a bold step when, over fifty years ago, the New 
York state geologists, Emmons, Mather, Vanuxem and Hall, dis- 
carded the then standard Wernerian classification to which 
McClure and Eaton had, with great pains, adjusted our Ameri- 
can geology, and, describing the New York rocks just as they 
found them, with new names and a new classification, formed 
the New York system. This New York system has become the 
standard formation-scale for American geology. 

But since the New York system was described, the fossils, 
which were then looked upon as mere marks by which to identify 
the formations, have come to be known as the evidences of the 
gradual evolution of species, each one holding its definite place 
in a continuous history of organism. As stratigraphy replaced 
the Wernerian lithology in classifying formations in 1840, so 
now paleontology comes forward to take the place of. strati- 
graphy as the true means of classifying geological periods. 

The case of the Catskill formation is in point. It has been 
a recognized fact, since the New York State Survey Reports 
were published, that the Catskill formation of New York was 
peculiar to the eastern parts of the state, and that it thins out on 
passing westward, and that the Chemung formation is well devel- 
oped in western New York, and becomes insignificant or is want- 
ing in the east. According to the single method of geological 
classification, it is necessary to call one above or below the 
other, and in our geological columns we have been accustomed 
to see the Catskill as the upper member of the Devonian lying 
above the Chemung, and because usage has vacillated between 
the time-scale and the formation-scale the confusion has been 
very difficult to formulate, or to bring to the minds of geologists. 

If we are discussing the formation-scale, it is true to the 
facts to speak of the Catskill formation as lying above the Che- 


DUAL NOMENCLATURE. I51 


mung formation, except that it does not express all the truth or 
the exact truth, for when the Catskill deposits are found in rela- 
tion to the Chemung deposits in a continuous section, some 
Catskill facies of sedimentation do succeed the marine Chemung, 
but it may not all succeed all the Chemung, as the testimony of 
numerous observers in Pennsylvania and further south shows. 

When, however, we are talking of the time-scale the confu- 
sion is more apparent; for it is clear that one period cannot 
both precede and follow a second period. Either the Catskill 
Period must follow the Chemung, or the Chemung must follow 
the Catskill, or else they are synonymous terms, and one is 
superfluous. When Mr. Darton proposes that Catskill be used 
in place of Chemung, he is reasonable on the old basis of the 
old method of classification, but the facts are not thus eluci- 
dated. The facts are that the Chemung period is synchronous with 
a part of the Catskill period, but that the Catskill formation is 
distinct from the Chemung formation, and when they occupy the 
same section the Catskill formation succeeds the Chemung. 

Those who have watched the discussion of the classification 
of the Upper Devonian, will remember that one of the greatest 
difficulties presented in the progress of field studies has been the 
fact that collectors have so frequently reported fossils where 
they ought not to be. Formations, classified as Catskill in the 
books, have yielded Chemung fossils, or, above so-called Catskill 
rocks, Chemung fossils have appeared, or above Hamilton rocks, 
in rocks regarded as Portage, have been found Hamilton fossils 
again. Geologists on the Pennsylvania Survey have met with 
serious rebuke for proposing Chemung-Catskill and similar names 
which have thrown discredit upon the integrity of the formations. 
These discrepancies have been interpreted to be evidence that 
the observers could not tell the two formations apart, or had 
been mistaken in their observations ; but the true interpretation 
is that the criteria for determining the divisions of the time-scale 
have disagreed with the criteria of the formation-scale. The 
latest phase of the discussion has appeared in the papers of 
Stevenson, Darton and Prosser, before cited. 


TZ LE JOURNAL OR IGHOLOG Y. 


In the discussion of Professor Hall’s paper at the Rochester 
meeting, the question came definitely before us as to the relative 
value of fossils and structure as means of determining or tracing 
equivalency of age of formations. In that discussion I main- 
tained that fossils are always the only certain means of carrying 
from one geological basin to another the evidence of time- 
relations of the deposits, that structure was indicative of equiva- 
lency only when actual continuity of a formation can be traced. 
Both of Mr. Stevenson’s* papers recognize the physical features 
of the formation to be of great importance in determining its 
position in the time-scale, and in his use of terms he appears to 
be classifying formations and yet using the language of the time- 
scale. In his presidential address he maintained, as quoted by 
himself, that the series of beds included within the Catskill and 
Chemung Periods should be grouped into one period, the 
Chemung, with three epochs, the Portage, the Chemung and the 
Catskill (page 320), and in his paper in 1893, he insists that the 
Chemung, and not the Catskill, is the epoch whose name should 
be applied to designate the whole group, while Catskill must be 
retained in its original signification only. 

Mr. Darton, on the other hand, is discussing the formation- 
scale alone. The principal purpose of his investigation is said 
to be to determine the relations and distribution of the Oneonta 
and Chemung formations (p. 203). In the passage on the status 
of the name ‘Catskill’ the author proposes to discontinue the 
use of Catskill as a co6rdinate formation term, and use the term 
“Catskill group,” to include the Portage and Chemung 
formations (p. 209). He maintains, correctly, I think, that the 
term Catskill has been applied in the past to beds of a certain 
lithologic character—the hard sandstones and red shales—and it 
has had no definite stratigraphic significance. The rocks of the 
Catskill Mountains and westward have no distinctive fauna of 
stratigraphic significance, and they cannot be correlated on 
paleontologic grounds (p. 208). 

*The Chemung and Catskill(Upper Devonian on the Eastern Side of the Appal- 


achian basin). A. A. A.S., Vol. 42. 
On the use of the name Catskill. Am. Jour. Sci., Vol. XLVI, p. 330. 


DUAL NOMENCLATURE. re 


On the assumption, which has been the common practice up 
to the present time, that the divisions of the time-scale and of 
the list of formations are synonymous, it is reasonable to insist 
that the Catskill and the Chemung are not correlative terms, and 
that, in case we apply them as formation names, the one must 
succeed the other, but I think we all know that this is not the 
case. We know, that is, that in western New York a continuous 
section takes us through Hamilton, Portage, Chemung, Con- 
glomerate and Carboniferous formations ;* that a like section in 
the meridian of Cayuga Lake takes us through Hamilton, an 
interval filled with Spiifer levis beds, the Ithaca group and 600 
feet with Portage fauna, then the Chemung, the Catskill, and 
finally the Carboniferous. Farther east the interval between the 
Hamilton and Chemung is filled by rocks with an advanced 
stage of the Hamilton fauna; then the Oneonta and next rocks 
with another stage of the Hamilton fauna, then the Chemung 
and the Catskill. Still farther east, Chemung drops out from 
the series ; and if we go on to Maine and Eastern New Bruns- 
wick, the Hamilton also falls out, and a long series with the 
latest marine fauna an Eodevonian Oriskany fauna, separated 
from the Carboniferous deposits by several thousand feet of 
deposits which, faunally and structurally, may be considered 
equivalent to the Catskill of New York. It is evident, thus, 
that at different localities the Catskill formation has a time 
value in one place equivalent to the closing part of the Chemung 
formation; at another place to the whole of the Chemung; at 
another to the upper part of the Chemung, and also an earlier 
stage during the formations of the Ithaca formation ; at another 
place it represents the whole upper Devonian, and, if we mean to 
extend the use of the name to Maine, to the whole of the upper, 
middle, and most of the lower Devonian. 

It is, therefore, clearly inappropriate to use the term Catskill 
as a name in the time-scale, because it has no common definition 
in that scale. It is an appropriate local formation name for 
deposits succeeding Hamilton or Chemung formations in Eastern 

tSee the table on p. 155. 


154 LETS WflON LIN AT OLN G OTE OG NA 


New York and farther southwest. It should not be applied to 
cover the three divisions of the Upper Devonian, because as a 
time indicator it is inappropriate, as just stated; and as a form- 
ation name it has already a use, and should not be used in two 
senses; and, thirdly, even if used in the more comprehensive 
sense, it is inapplicable because the Portage and Chemung are 
not represented, at least only imperfectly, in the geological area 
named Catskill. 

The Catskill is a distinct and well defined geological form- 
ation, but it is not a period or an epoch, nor does it represent 
any particular period of geological time. The classification of 
the Upper Devonian deposits is a very difficult matter when it is 
attempted to make a continuous series of the formations of New 
York alone. As I have previously shown, the succession of 
faunas in the sections of New York rocks at distances of not 
over fifty miles apart make plain this fact. At the Cayuga lake 
meridian, the section is Hamilton, terminating with Tully lime- 
stone and Genesee shale, then the Ithaca group, which has first 
a Portage fauna, then the Ithaca fauna, third, the Portage fauna 
again, and finally Chemung capped by Catskill and Carboniferous. 
A little further east of the Chenango valley, it is Hamilton; then 
a fauna intermediate between Hamilton and Ithaca (but no Tully 
or Genesee); then the Oneonta, a brackish and fresh water fauna; 
then the late Ithaca fauna, still with Hamilton types in it; no Port- 
age fauna, but Chemung fauna following the upper Ithaca fauna.* 

In this faunal succession there is a clear indication of the age 
of the Oneonta sandstones. It is clearly in the midst of the 
rocks characterized by the Ithaca fauna. As I have shown in the 
paper referred to,? the marine Brachiopod faunas occupying the 
place between the Hamilton and the Chemung faunas in Central 
New York, of which the Ithaca is the best known, are modified 
successors of the Hamilton, or Mesodevonian fauna, and the 
Oneonta group, with its fresh and brackish water fauna is in the 

WILLIAMS: The Classification of the Upper Devonian. Proc. Am. Assoc. Adv. 
Sci., Vol. XXXIV., p. 225, 1886. 
2Proc. A. A. A. S., XXXIV., 1885, pp. 222-3. 


DUAL NOMENCLATURE. 156 


midst of it; that is, the Ithaca fauna is both below and above it. 
Again, upon going further west, the same interval is filled by a 
non-brachiopod marine fauna, z. ¢., that of the typical Portage 
group of Genesee valley, and the Ithaca group of Ithaca is in the 
midst of the corresponding rocks of the Portage, as the Oneonta 
is in the midst of the Ithaca. This I interpreted, in the paper 
referred to, as indicating that the succession of faunas was con- 
trolled by oscillation of levels during the accumulation of the 
deposits, the eastern shores rising during the first half of the 
Portage (of the Genesee valley series) so that, during the par- 
ticular stage represented by the fossiliferous zone of the Ithaca 
group, Portage fossils were being accumulated in the Genesee 
valley sediments, Ithaca fauna at Cayuga lake meridian, and, from 
Chenango eastward to Oneonta, sands with fresh water Amnigenia 
and Holoptychius characteristic of the Catskill formation. 


THE FORMATIONS OF THE DEVONIAN SYSTEM IN THE APPALACHIAN 
REGION AND THEIR RELATIONS TO THE TIME-SCALE. 


% 


FORMATION SCALE. 
TIME SCALE. 
GENESEE RIVER.|CAYUGALAKE,| DELAWARE SON MAINE. 
co. RIVER. 
OCA OME KOUS seme ueer sl fitment eer) Dialllle' akc eee act lh gt pee meer Rance casera ye ty el eto pea ae 
( |\Conglomerate Catskill 
Chong ——————= Catskill 
a -—————— 
Chemung | Catskill 
| IPE H 
Neodevonian......... Pontene Teen Onan 
| IP# H? H? Catskill 
Genesee 
2 (S@MESSO' epee 
Tully 
: Hamilton | Hamilton | Hamilton | Hamilton 
BCS TO eh Iele a ear Marcellus | Marcellus 
f Corniferous |Corniferous} Onondaga 
Onondaga | Schoharie | Schoharie 
Eodevonian.......... Caudagalli |Caudagalli | __ 
Oriskany | Oriskany Oriskany 
Oriskany | Oriskany 
INAS RTO TEARS cores cocoa RD SAH OH OPE STC wets (aMareeae ee vertig fale tosssrbacnte Fe Ri ISy a! he rene et Ne nee 


156 VHE JOURNAL (OF “GHOLUOG VY. 


The table on page’'155 presents the facts regarding these forma- 
tions, and what I conceive to be the chief difficulties in attempt- 
ing to use a single nomenclature and classification. The question 
at once arises how will a dual nomenclature help us over these 
difficulties. 

On the left I have placed a part of the time-scale adjusting 
the formation-scales for the several sections, approximately as I 
think the fossils indicate their time relations to have been. 

Formations may be described for a particular geological section 
with precision as to kind of rock, stratigraphical sequence and 
thickness, and, as we compare one section with another, we are 
obliged to become more indefinite in our description and speak in 
generalities, or averages ; and therefore the wider we extend the 
use of a formation name, the less accurate and the more indefinite 
does it become. 

On the contrary, in the distinguishing of time-relations or 
position in the time-scale, the individual facts, the local handful 
of fossils are the more indefinite, indicating only, it may be, 
Paleozoic or Mesozoic age. The extension of the comparison to 
the study of fossils above and below, and to the comparison of 
fossils in adjoining sections, and to their geographical distribution 
for a wide extent, increases the precision in locating position in 
the geological time scale. 

It happens, therefore, that, while formation definitions are best 
constructed in the field in the presence of the actual rock section, 
the time definition becomes more accurate the more thorough the 
investigation of the fossils is made. Hence in constructing a 
time-scale, it begins properly with the grander divisions, and it 
is built up and perfected by subdivision, whereas the forma- 
tion-scales begin with the lesser strata and are elaborated and 
completed by adding together successive strata. 

The grander divisions of the time-scale are already in use. 
These are universally known as the Paleozoic, the Mesozoic, and 
the Cenozoic. The primary sub-divisions of these geological 
times are also very widely understood and used. They may be 
called evas, and are named Cambrian, Ordovician, Silurian, Devo- 


DUAL NOMENCLATURE. 157 


nian, Carboniferous (constituting the eras of Paleozoic time), 
Triassic, Jurassic, and Cretaceous (the eras of Mesozoic time), 
and Eocene, Neocene, and Recent (the eras of Cenozoic time). 
Each of these eras is known, not by the formations which repre- 
sent it, but by the fossils which characterize it. Proceeding in 
the same manner, I would propose that we subdivide the eras 
into Periods, according to the lines which paleontologists have 
generally come to recognize as convenient and natural, making a 
three-fold (or in some cases a two-fold division) of each era, and 
that they be distinguished by prefixing the syllables Zo, Meso and 
Neo, to the name of the era, thus : the Zocambrian, or the period of 
the Olenellus fauna, the Wesocambrian, or the period of the Para- 
doxides fauna, the Veocambrian, or the period of the Dikelloceph- 
alus fauna, and in the Devonian, the Lodevonian, Mesodevonian, 
and (Neodevonian, and in the same manner for each of the other 
eras. 

Although attempts have been made to make finer divisions 
of the time-scale, into Epochs and, lately, into Hemere,’ it is 
doubtful whether our knowledge of the history of organisms is 
sufficiently advanced to enable paleontologists to define the fauna 
of an epoch so that it can be made use of for more than a thou- 
sand miles of geographical extent, and the hemere of single species 
cannot be considered as precisely alike in two distinct geological 
provinces. 

In the application of this time-scale to any particular case the 
degree of minuteness of definition will depend upon the knowl- 
edge we have of the time relations of the contained fossils. Inthe 
case in hand, the fauna of the Catskill is not sufficiently definitive 
in itself to enable us to be more precise than to assign it to the 
Devonian Era. This is affirmed by the fact that, in England, the 
old Red Sandstone is known not as a part of, but as the represen- 
tative of the whole Devonian. If we attempt to define the age 
of the Catskill formation by faunas immediately preceding or 
succeeding it, the definition in time is equally indistinct, because 


tS. S. BUCKMAN: The Bajocian of the Sherborne Districts, its Relation to Subjacent 
and Superjacent Strata. Q.J.G.S., Vol. XLIX., p. 479-522, Nov., 1893. 


158 THE JOURNAL OF GEOLOGY. 


not alike for different sections which are geographically not 
greatly separated from each other. 

The Catskill formation is primarily a local formation exhibited 
in the Catskill mountain region of New York, distinguished phys- 
ically as a series of sandstones and shales with greater or less 
red-color, and by the absence of marine fossils, and the occasional 
presence of shells and fish believed to have been of fresh or 
brackish water habitats. It is the local expression of the broad- 
ening shore condition of the continental elevation which brought 
in the coal-making, or Carboniferous age of eastern North Amer- 
ica. Asa formation, it is separated from what went before by the 
reddening, or graying of the sandstones and shales, their coarser, 
more irregular structure, the departure of marine organisms, and 
the occasional appearance of brackish water shells, fishes, and 
some fossil drift-wood and plants. In relation to the me scale, 
the period of beginning of this formation varies with the regions 
in which it is exposed. At its extreme eastern extension, on the 
peninsula of Gaspe, and in eastern New England, it began in the 
Eodevonian Period. Along the Hudson River, it began at the 
beginning of the Neodevonian, or perhaps before the termination 
of the Mesodevonian. In the region of Oneonta and westward 
it began soon after the beginning of the Neodevonian Period, and 
then withdrew eastward, the marine conditions returning over the 
region leaving the Oneonta formation as its record, and later in 
the middle of the Neodevonian, it returned and continued on to 
the close of the Devonian era. In the region of Bradford County, 
Pennsylvania, it did not begin to be deposited till near the close 
of the Neodevonian Period. Farther west the Olean Conglomer- 
ate marks the final close of the Deyonian Era, and the formation 
in question did not begin till after the close of the Devonian. In 
the eastern Pennsylvania and more southern sections, its age varies 
with the locality. In general, it is terminated above by indica- 
tions of the presence of permanent land conditions, either massive 
beds of rounded pebbles or conglomerates, or thin beds of coal 
or carbonaceous shales, or, in the absence of actual change in 
formation, the line is arbitrarily set by the supposed tracing of 


ee 


DUAL NOMENCLATURE. 159 


equivalency of stratigraphical position by the structure from some 
region in which such marks are evident. 

The Pocono and the Mauch Chunk are, as formations, but the 
continuation of the Catskill formation upward and are of local 
value as formation-names, but of little or no value as elements of 
a time-scale. 

Thus the Catskill may continue to appear in the list of forma- 
tions of New York, and the Appalachian province, where it gener- 
ally appears as a Neodevonian formation, but it is useless to define 
or to discuss its more exact position in the time-scale, because its 
own time-criteria range through the whole Devonian Era, and its 
relations to formations whose time-criteria are more exact is indefi- 
nite and inconstant. 

If we grant the truth of the general principle here set forth, 
it is evident that the increase of formation names can be no more 
objectionable than the increase of the names of mountains; and 
that there is no more reason for applying the same name to two 
formations which are of the same age, but differ in position and 
structure, than there is in giving two names to mountain ridges 
of the same range. The classification of formations into groups 
or systems will depend upon considerations of geological structure, 
_ and only secondarily upon time considerations; and even in the 
latter case, only because the same general geological events have 
affected the sedimentation in a similar way for a wide extent 
geographically. 

On the other hand, the time-scale will depend for its classifi- 
cation upon the fossils and not upon structure. Stratigraphical 
sequence, of course, is important in reading fossils, but only as 
in a sentence, or on a page, the sequence of the words is impor- 
tant. 

An organic species, or a genus, or an order lived only during 
a particular period of time, and it is for this reason that the fossils 
have an intrinsic time-value, but a mineral, or a rock may have 
been formed under like conditions and present like characteristics 
at any period of geological time. I refer of course to clastic 
rocks, and those formed through processes of sedimentation. 


160 THE JOURNAL OF GEOLOGY. 


Marine invertebrates for the Paleozoic, and later marine verte-_ 
brates constitute the most satisfactory means for discerning geo- 
logic age, because the oceans, in which they live, are of world- 
wide extent and inter-communication. They are distributed 
around the globe, and from pole to pole, so far as the adaptation 
to conditions of environment will permit. Hence, we find it to 
be a fact that, at every period of geological time, there are repre- 
sentatives in all regions of the globe of the same species, or of 
closely allied species such as to mark the close correlation of time 
of their living. While this is true, it must be borne in mind that 
correlation cannot be made by fossils to a finer degree of dis- 
crimination than the facts of specific integrity allow. The life- 
period of species is not uniform, and the wider the distribution, 
the longer is, as a rule, the range; so we find, in practice, that 
with the present knowledge of fossils it is rarely possible to dis- 
criminate age to a finer degree than that indicated by the periods, 
Eocambrian, Mesocambrian, and Neocambrian, or similar periods 
for the other eras. Within such general limits, time relations can 
be discriminated by the fossils alone, and the progress of science 
will enable us to recognize more minute divisions of time as we 
proceed. 

On the other hand, formations, being local phenomena, are dis- 
criminated with greater precision locally, and the indefiniteness 
in application of formation names increases with the wideness of 
the territory covered. No classification cf terranes can be of 
universal application, for no formation, or formation character, or 
criterion of determination, is of world-wide extent. The time 
divisions are more precisely defined the larger they are ; the for- 
mation divisions are more precisely defined the smaller they are, 
and progress of knowledge will extend the precision in opposite 
ways for the two scales. 


HENRY SHALER WILLIAMS. 
YALE UNIVERSITY, 
NeEw HAVEN, CONN. 


ORIGIN AND CLASSIFICATION OF THE 
GREENSANDS OF NEW JERSEY. 


CONTENTS. 

INTRODUCTION. 

General Stratigraphical Features. 

Description of the Formations. 
Matawan Formation. 
Navesink Formation. 
Redbank Formation. 
Rancocas Formation. 
Manasquan Formation. 
Shark River Formation. 

Origin of Greensand. 

Genesis of the Deposits. 

Source of the Materials. 

Taxonomy. 

General Conclusions. 


INTRODUCTION. 


Dur1NG the past two years the writer has been carrying on 
investigations upon the Cretaceous and Tertiary formations of 
New Jersey under the joint auspices of the State and National 
Geological Surveys. A preliminary study of the whole area 
was followed by the mapping, with the aid of others,” of three 
United States Geological Survey atlas sheets in the northern 
portion of the district, and more recently by the critical exam- 
ination of five type sections across the state. The results of 
the earlier investigations have just been published, while the 
later work will appear in the next annual report of tine Seas 
Geologist. 

In an area which had received such full investigation by as 
competent a geologist as the late Professor Geo. H. Cook, for 

* Read before the Geological Society of America, at Boston, December, 1893. 


2 The writer had associated with him as assistants Messrs. C. W. Coman, H.S. 
Gane and R. M. Bagg. 
3 Rept. of the State Geologist of N. J. for 1892, pp. 167-246. 
161 


162 THE JOURNAL OF GEOLOGY. 


so many years the head of the State Survey, it was deemed 
advisable to act with great deliberation before proposing any 
important changes in the classification. Accordingly the first 
report to the State Geologist was limited to the fewest possible 
alterations in the accepted names of the formations, and the 
work made to conform so far as it was possible with the earlier 
results of the State Survey. As the work has progressed the 
necessity of modifying the classification hitherto adopted has 
become apparent, and such changes are presented at this time. 
The use of lithologic terms for the formations in the earlier 
nomenclature will be in the future discarded for place names, 
the older terms being retained to designate their economic 
equivalents. Local terms have been adopted, care being taken 
to select such as would characteristically represent the forma- 
tions. The names of rivers, hills, and towns, in the vicinity of 
which typical sections are found, have been generally employed. 
In this manner the results of the work in New Jersey are brought 
into conformity with methods generally adopted at the present 
time in other areas. 

The work carried on during the past field season in portions 
of the area never before studied to any extent on account of the 
thick covering of recent deposits, reveals the fact that the 
divisions established chiefly from an examination in the extreme 
north, are remarkably persistent. This knowledge has been 
gained to a large extent from recent well openings and borings 
made at frequent intervals by the writer and his assistants. The 
unconsolidated character of the sediments render it possible to 
pursue this method of investigation throughout the region with 


the hope of far reaching results. 


GENERAL STRATIGRAPHICAL FEATURES. 

The geological formations of the coastal area of New Jersey 
represent a nearly complete sequence from the Cretaceous to the 
Pleistocene. They forma series of thin sheets which are inclined 
slightly to the southeastward, so that successively later forma 


tions are encountered in passing from the northwestern portion 


THE GREENSANDS OF NEW JERSEY. 163 


of the district toward the coast. Oscillation in the position of the 
shore line, and later denudation have occasioned, in many 
instances, a marked divergence from these normal conditions, so 
that detached areas are frequently found far removed from the 
body of the main outcrop. 

The formations of the New Jersey coastal area and their 
economic equivalents are given in the following table : 


} Age. Formation. Economic Equivalent. 
Pleistocene - - Columbia Formation 
Lafayette U6 
Neocene - - y 


Chesapeake ‘“ 


Eocene - - - Shark River es Upper Marl Bed | 
Rancocas if Middle Marl Bed | rae 
; ; Redbank ss Red Sand EDN 
Cretaceous a Gauak: 


Navesink at Lower Marl Bed 
Matawan “s Clay Marls 
Raritan ue Plastic Clay 


‘ 
anasquan . \ 
i 
| 
| 


The greensands characterize all the deposits from the Mata- 
wan formation to and including the Shark River formation. The 
glauconite appears in varying amounts and under different con- 
ditions in these several formations, so that the lithologic features 
are often sufficiently distinctive and persistent to be of the 
greatest service in the determination of the horizons. The 
presence of greensand has not been observed in the Raritan for- 
mation which underlies, nor in the Chesapeake formation which 
overlies, this series of glauconitic deposits. 


DESCRIPTION OF THE FORMATIONS. 


Matawan formation (Clay Marls).—On account of the exten- 
sive and typical development of the Clay Marls on the shore of 
the Raritan Bay in the vicinity of Matawan Creek, and along the 
banks of the latter stream, the name Matawan formation is pro- 
posed for the deposits of this horizon, 

The greensand is a less pronounced feature than in the over- 
lying formations. The deposits consist for the most part of dark 
colored clays with interbedded layers of sand, the latter becom- 
ing very pronounced in the upper portion of the formation. At 
some points beds of greensand appear, but they are generally 


164 THE JOURNAL OF GEOLOGY. 


thin and of very narrow geographical extent. The deposits are 
largely fragmental, with here and there an admixture of carbonate 
of lime derived from the shells of organisms. 

The most extensive section is afforded by the bluffs on the 
shores of the Raritan Bay, between the mouth of Cheesequake 
Creek and the Navesink Highlands. From this point the forma- 
tion extends southwestward across the state, the best exposures 
being found along the stream channels entering the Delaware 
River from the east. Both along Crosswicks and Pensauken 
Creeks the strata are highly fossiliferous, at the latter locality 
over a hundred species having been identified. In the main the 
forms are the same as those in the overlying Navesink formation, 
although some are distinctive. 

From the surface outcrops the Matawan formation has been 
estimated to have a thickness of 275 feet. 

The most striking differences both in the character of the mate- 
rials and the thickness of the beds, are shown by well borings 
along the line of dip. A recent boring at Asbury Park pen- 
etrated the Navesink formation (Lower Marl Bed) at 400 feet, 
beyond which for a distance of over 400 feet typical Clay Marls 
were encountered. From 750 to 780 feet glauconitic layers were 
found, while the deposits in general are finer and more regularly 
stratified than in the surface outcrops to the westward. 

Navesink formation. (Lower Marl Bed).—The lower Marl 
Bed has an extensive development throughout the region of the 
Navesink Highlands, in the vicinity of the village of Navesink, 
and along the north bank of the Navesink River, so that the name 
of Navesink formation may be with propriety employed. 

Greensand forms the distinguishing feature of the deposits. 
The lower portion is frequently quite sandy, in this respect show- 
ing the change from the sandy layers of the upper portion of the 
Matawan formation, upon which it lies conformably, to the typical 
greensands of the Navesink formation. The upper portion again 
shows the presence of much land derived material; it is highly 
argillaceous and just at the top frequently arenaceous. The green- 
sands along the thinned out western edge of the Navesink forma- 


THE GREENSANDS OF NEW JERSEY. 165 


tion have been oxidized to so great an extent that their separa- 
tion from the red sands of the Redbank formation is often a dif- 
ficult matter. 

On account of the great economic importance of the green- 
sand beds of the Navesink formation frequent pits have been dug 
into it all along its line of outcrop from the northern to the 
southern end of the district. Asa result the strata may be studied 
to great advantage. 

A magnificent exposure is found in the great bluffs of the 
Navesink Highlands facing the Raritan Bay, while excellent sec- 
tions are to be found along many of the streams that cut through 
‘the formation. The beds are highly fossiliferous and the most 
varied fauna in the New Jersey Cretaceous is found at this horizon. 
Between 300 and 400 species have been described. 

The Navesink formation has a pretty constant thickness of 40 
feet, although locally ranging from 30 to 60 feet. The deposits 
have been found to be remarkably persistent in character both 
along the strike and dip, so far as they have been examined. 

Redbank formation (Red Sand).—The bright red sands of this 
formation afford one of the most striking features of the country 
throughout the marl district. They are extensively developed 
in the vicinity of Redbank, and on that account the name Red- 
bank formation is proposed for the deposits of this horizon. 

The strata are glauconitic throughout, although the great pre- 
ponderance of coarse arenaceous sediments has facilitated the 
oxidation of the greensand, changing the green color of the beds 
to red or brown. The lower portion of the Redbank formation 
is often composed of black sand or sandy clay, while at the top 
of the formation there is an indurated clayey layer generally of a 
distinctly greenish color. This hardened stratum has had an 
important influence in the development of the topography of the 
marl district, and especially in the extreme north the higher hills 
are largely due to its presence. The fossils are in the main the 
same as in the preceding formations, but on account of their poor 
preservation have not up to the present time been very fully 
studied. The indurated layers have afforded the greater number. 


166 MieS, ONAL (UI (GOMOENG, 


The formation has a rather constant thickness of 100 feet. 

Rancocas formation (Middle Marl Bed).—The Middle Marl 
Bed is not as prominent a feature in Monmouth county where the 
type localities for the other formations are found as farther south- 
ward. The Rancocas Creek in Burlington county cuts through 
the Middle Marl Bed exposing a full sequence of the deposits of 
that formation, while in the neighboring area extensive exposures 
of the strata are found: 

The formation is largely a greensand, although much more 
highly glauconitic in the lower than in the upper half of the for- 
mation. Although the lower half is largely a pure greensand, 
it becomes in some portions of the state very argillaceous 
toward the base, forming the so-called ‘‘chocolate marl,” while 
toward the top it becomes crowded with shells, the upper two 
feet characterized by the presence of Terebratula Harlant, the 
most persistent fossiliferous zone in the state. The upper half 
of the formation is highly calcareous, frequently appearing as 
limestone ledges, known as ‘yellow limestone,” and often contain- 
ing as much as 80 per cent. of carbonate of lime. It is extremely 
fossiliferous, and has afforded many beautifully preserved speci- 
mens of Bryozoa, Echinodermata and Foraminifera. The fossils 
are, in the main, different from those in the underlying forma- 
tions. 

The strata reach a thickness of about 45 feet. 

Manasquan formation (Lower portion of the Upper Marl Bed). — 
The name Manasquan Marl was in an earlier publication made to 
include the Yellow Sand, together with the “green sand” and “ash 
marl’ of the Upper Marl Bed of Professor Cook. For that hort- 
zon the term Manasquan formation is retained. It is typically 
developed in the valley of the Manasquan River and its tribu- 
taries. 

Like the preceding formation it is essentially a greensand 
throughout, although distinctly quartzose in the lower part, and 
at times argillaceous in the upper layers. The fossils so far as 
observed are confined exclusively to the more highly greensand 
member, but the number of species is not large. The high per- 


THE GREENSANDS OF NEW JERSEY. 167 


centage of soluble phosphates in the Manasquan marl has long 
given it a high reputation as a fertilizer. 

The thickness of the strata has been estimated at 65 feet. 

Shark River formation (Upper portion of the Upper Marl 
Bed).—The term Shark River Marl was earlier employed by 
the writer to embrace the “blue marl” of the Upper Marl Bed, 
which has been generally referred in recent years to the Eocene, 
although the beds are conformable with the underlying strata 
concerning whose Cretaceous age there is apparent unanimity of 
opinion. 

The Shark River formation is a characteristic greensand with 
a slight admixture of argillaceous materials, while a hardened 
and stony layer is found directly at the top. The fossils are 
numerous, but cannot be readily compared with those from the 
Eocene areas to the southward. The strata of the Shark River 
formation have not been found at any point to exceed 12 feet in 
thickness. 

The Shark River formation closes the series of greensand 
deposits. It is unconformably overlain by strata of a very dif- 
ferent character which show evidence of marked mechanical dis- 
turbances and rapid deposition. 

Throughout the entire sequence of deposits just described, 
the presence of greensand has been the most distinguishing 
feature. Its origin is therefore a matter of great importance to 
the understanding of the several formations, and will be briefly 
discussed. 

ORIGIN OF GREENSAND. 

Greensand has been found in greater or less amounts at 
nearly every geological horizon, from the Cambrian down to the 
present time. It is not an original deposit of clastic origin, but 
secondary in character. An examination into the conditions of 
production which surround those deposits forming upon the floor 
of existing seas will afford an explanation of the strata of past 
geological time. . 

Great light has been thrown upon this subject as a result of 

he deep-sea dredgings which have been made in recent years 


168 LTE DJ QOLINAL OL RGLAO IE OG NA 


by the vessels sent out on scientific expeditions by the various 
governments of Europe and our own. The most important of 
these expeditions has been that of the Challenger, sent out by 
the British government in the years 1872-76. In the report 
upon the Deep Sea Deposits recently published as a result of 
that expedition, Professors Murray and Renard, the authors, 
present the latest results upon the character and distribution of 
greensand, and, at the same time, propose a theory to account 
for the chemical changes which have taken place to produce the 
mineral glauconite which characterizes all greensand deposits. 

A typical greensand is composed of glauconite associated 
with greater or less amounts of land-derived material. Among. 
the more common minerals thus found are quartz, feldspar, horn- 

blende, magnetite, augite, zircon, epidote, tourmaline and garnet, 
together with fragments of the continental rocks, such as gneiss, 
mica-shist, granite, diabase, etc. A variable amount of calcareous 
matter derived from the shells of organisms is also present. 

The glauconite occurs in minute grains, seldom exceeding 1 
mm. in diameter, although they may become agglomerated into 
nodules several centimeters in diameter by means of a phos- 
phatic cement. The grains are always more or less rounded, 
and at times mammillated, with irregular surface outline. They 
are generally black or dark green in color, but become brighter 
green upon being crushed. The surface of the grains is some- 
times covered with fine punctures, while at other times it is 
smooth and shining. Some of these glauconitic grains are dis- 
tinct internal casts of foraminifera, and of other calcareous 
shells, but more often they only reproduce indistinctly the form 
of the chambers, or show no definite connection with the organ- 
isms in which they originated. 

It is estimated that greensand deposits cover approximately 
1,000,000 square miles of the sea floor. They are found limited 
to those portions adjacent to the coasts, and, for the most part, 
along the higher parts of the continental slopes where land-de- 
rived materials are deposited in perceptible, yet small amounts. 
The production of glauconite seldom reaches to greater depths 


THE GREENSANDS OF NEW JERSEY. 169 


than g00 fathoms, and most commonly takes place between 100 
and 200 fathoms. The entrance of large rivers into the sea or 
the prevalence of strong currents would tend to interfere with 
its formation, so that the area of distribution of greensand is 
seldom continuous for great distances. 

Although greensand is not known to be formed Except im 
the presence of land-derived materials its production is accom- 
plished through the intervention of foraminifera. Their connec- 
tion with the formation of glauconite was first shown by Ehren- 
berg* in 1855 as the result of a study of greensand from many 
deposits in Europe and America. Professor Bailey? the succeed- 
ing year stated that the formation of greensand is likewise taking 
place on the floor of existing seas, and under the same conditions 
that existed in past geological ages. 

According to Murray and Renard the chambers become 
filled with muddy sediment, and “if we admit that the organic 
matter enclosed in the shell, and in the mud itself, trans- 
forms the iron in the mud into sulphide, which may be oxidized 
into hydrate, sulphur being at the same time liberated, this sul- 
phur would become oxidized into sulphuric acid, which would 
decompose the fine clay, setting free colloid silica, alumina being 
removed in solution ; thus we have colloid silica and hydrated 
oxide of iron in a state most suitable for their combination.” 
The potash which is necessary to complete the composition of 
glauconite may be derived from the decomposition of the frag- 
ments of crystalline rocks or their common constituents, ortho- 
clase and white mica. 

Two conditions then are requisite for the production of glau- 
conite, first the deposition of mineral particles of land-derived 
origin; and second, the presence of foraminifera. In the 
absence of either the production of greensand will not take place. 
It is further seen that the formation of greensand is retarded 
and finally ceases altogether as the amount of deposition of 
land-derived materials increases adjacent to the coasts. Only 

* Abhandl. d. k. Akad. d. Wissenschaften zu Berlin, 1855, pp. 85-176. 

? Boston Soc. Nat. Hist., Proc., Vol. 5, 1856, pp. 364-368. 


( 


170 LTE SO CLI VALS OF NG LAOS OG A 


then within circumscribed limits, which are constantly subject to 
modification, is the production of greensand possible. 


GENESIS OF THE DEPOSITS. 


The opening of the Cretaceous period along the Atlantic 
border witnessed the deposition of large amounts of irregularly 
stratified sands and clays together with beds of gravel in the 
vicinity of the coasts. It was a period of great mechanical dis- 
turbance over the area of deposition, and both the physical and 
faunal characters of the strata point to the close proximity of 
land, while enclosed basins doubtless existed for a portion of the 
time. 

With the opening of the epoch of greensand deposition, as 
represented in the Matawan formation, much the same condi- 
tions at first prevailed. Alternating beds of sand and clay were 
laid down, but gradually the coarser elements disappeared, depo- 
sition became less rapid and greensand was locally developed. 
The conditions for greensand production were not widely 
extended nor long existent, for successive periods of rapid and 
slow accumulation of materials continued to the close ot 
Matawan deposition. 

With the advent of the Navesink epoch land-derived mate- 
rials became greatly reduced in volume and shortly ceased 
almost altogether, so that throughout the area of deposition 
there was formed at this horizon some forty feet of highly glau- 
conitic greensand. Toward the close of this period terrigenous 
deposits became more pronounced, but the production of giau- 
conite did not altogether cease. 

With the opening of the next epoch, represented by the Red- 
bank formation, dark sands in which the proportion of glauconite 
was very small were at first deposited. Throughout the whole 
series of beds glauconite is found distributed in greater or less 
amounts, but at no time did its production reach the prominence 
that it had during the previous epoch. The marked admixture 
of coarse elements throughout most of the deposits rendered 
them later subject to the ready percolation of water by which 


THE GREENSANDS OF NEW JERSEY. fA 


the complete oxidation of the glauconite was accomplished. 
Toward the close of the Redbank epoch finer sediments prevailed, 
and there is every evidence that land-derived materials found 
ingress to the area of deposition in gradually lessening amounts. 

The succeeding Rancocas epoch was a time of slow accumu- 
lation of continental materials so that the production of glau- 
-conite went on unhindered. During the latter portion of the 
epoch, however, there must have been a great profusion of animal 
life, for the deposits show a marked admixture of carbonate of 
lime, while in many instances the shells are still in an excellent 
state of preservation. The formation of glauconite was not 
interrupted, although its relative proportion is at times much 
diminished by the great amount of carbonate of lime which may 
in some instances reach eighty per cent. of the whole. 

The Manasquan epoch was characterized throughout by the 
constant formation of greensand beds, although land-derived 
materials in considerable amounts reached the area of deposition 
during the early portion of the period. 

No very marked changes apparently affected the region 
toward or at the close of the Cretaceous, but the same conditions 
persisted on into the Eocene, as shown in the Shark River forma- 
tion, during which period similar deposits with very different types 
of animal remains were accumulated. At the close of the Shark 
River epoch the conditions favorable for the formation of green- 
sand ceased, not to be again revived during the period of forma- 
tion of the coastal deposits in New Jersey. 

The succeeding epochs gave proof of much shallower waters, 
while the ancient Cretaceous-Eocene sea floor frequently stood 
above sea level and along its landward portions constantly lost 
as the result of erosion. As the land rose higher and higher in 
late geological history further inroads were made until the deeper 
portions of the ancient sea bottom were exposed by the forces of 
denudation. 

SOURCE OF THE MATERIALS. 

The source of the materials which constitute the several 

formations of the coastal region of New Jersey has not been 


172 THE JOURNAL OF GEOLOGY. 


altogether satisfactorily explained, although the deposits indicate 
that they were largely derived from crystalline rocks. 

That the red sandstones and shales of the Jura-Trias (Newark 
Formation) which adjoin the coastal series upon the landward 
side have not been the source of the materials is a striking fact, 
and one which has been largely commented on in the past. By 
some it has been supposed that an area of crystallines must have 
existed to the eastward to afford the materials for the deposits 
under consideration. A study of the drainage of the Jura-Trias 
belt which separates the coastal formations from the area of crys- 
talline rocks beyond, is of interest, however, in showing the prob- 
able extension of the coastal deposits quite over the red sand- 
stones and shales of the Jura-Trias to the border of the crystal- 
line region and at the same time affords a sufficient explanation 
for the absence of sediments derived from the Jura-Trias itself. 
The evidence for this has been recently presented by Davis* in 
the National Geological Magazine, and the reader is referred to 
the article for a fuller explanation of the subject. 

Accepting the explanation of Davis as highly probable we 
may look for the source of the land-derived materials out of 
which*the greensand deposits are formed, in northwestern New 
Jersey, eastern Pennsylvania and southeastern New York, in a por- 
tion of that tract of crystalline rocks which stretches along the 
eastern side of the continent. A separation of the mineral con- 
stituents of the greensand deposits shows a preponderance of 
both the constituent and accessory minerals which characterize 
those rocks. It seems conclusive, therefore, that the area men- 
tioned was the source of the materials for the greensand deposits 
of eastern New Jersey. 

_TAXONOMY. 

The geological formations of New Jersey early attracted the 
attention of geologists, and Professor Peter Kalm? of Sweden, 

™ Nat. Geog. Mag., Vol. II., No. 2, pp. 1-30, 1890. 


2En Resa til Norra America 8vo. 3 vols. 1753-61, Stockholm. Translations in 
English by J. R. Forster Ist. Ed. 1770-71, 2nd. Ed. 1772, another Ed. in J. Pinkerton’s 
Voyages, Vol. 13, 1812; in German by J. H. Murray, 1754-64; in French by L. W. 
Marchand, 18509. 


THE GREENSANDS OF NEW JERSEY. 78 


who was sent out in 1749 under the auspices of the Royal Acad- 
emy of Sciences to make a study of the various branches of nat- 
ural history in America, presents many interesting observations 
concerning the deposits under consideration. He spent much of 
his time in New Jersey. 

In 1777, Dr. Johann David Schoepf* of Germany, visited Amer- 
ica in order to study the geological features of the eastern portion 
of the continent. His observations and comparisons of the coastal 
plain formations, especially of New Jersey, mark considerable 
advance over those of Kalm. The importance of his investiga- 
tions have not been very generally recognized by later writers, 
but he showed a remarkably keen insight into the geology of 
eastern America which was lacking on the part of some of his 
successors. 

The first attempt at a correlation of the deposits of New Jer- 
sey with the geological column then established in Europe was 
made by William Maclure? in 1809, in his ‘Observations upon the 
Geology of the United States.” In this publication the coastal 
deposits of New Jersey are collectively referred to the “ Alluvial 
formation,” the fourth of the main divisions of geological strata 
proposed by Werner. The work was subsequently revised and 
enlarged, appearing in book form in 1817. 3 

Professor John Finch was the first to propose a division in the 
coastal plain deposits of New Jersey. In his ‘‘ Geological Essay 
on the Tertiary Formations in America” he states that what has 
been called the “Alluvial formation” by earlier writers ‘‘is identi- 
cal and contemporaneous with the newer Secondary and Tertiary 
formations’’ of other portions of the globe. 

A few years subsequent to this, Professor Lardner Vanuxem4 
through his friend Dr. S. G. Morton, presented the criteria for a 

« Beitrage zur mineralogischen Kenntniss des 6stlichen Theils von Nord Amerika 
und seiner Gebiirge. 8vo, 1787, 194 pp. Erlangen. 

2 Amer. Phil. Soc. Trans. Vol. 6, 1809, pp. 411-428. Translation in Journal de 
Physique, Vol. 69, 1809, pp. 204-213 and Vol. 72, 1811, pp. 137-165. 

3 Philadelphia, 8vo, 130 pp. Also in Amer. Phil. Soc. Trans. new series, Vol. 1, 
1817 pp. 1-92; and Leonard’s Zeitschrift, Band 1, 1826, pp. 124-138. 

4 Amer. Jour. Sci. Vol. 7, 1824, pp. 31-43. 


174 THE JOURNAL OF GEOLOGY. 


more complete and definite recognition of the several members 
of the coastal series in which both the Cretaceous and Tertiary 
formations were described in some detail. 

With the establishment of the official geological survey of 
New Jersey under the direction of Professor H. D. Rogers* the 
first attempt was made at a detailed differentiation of the local de- 
posits. The formations, beginning at the bottom, were designated 
as follows: Clays and Sands, Greensand, Limestone, Ferruginous Sand, 
and Lrown Sandstone. Although the various members were not 
clearly defined and widely different materials were included under 
the same division, yet the easterly dip of the strata was observed 
and the broader distinctions in the stratigraphy of the area were 
recognized. 

Dr. T. A. Conrad,’ in 1848, first suggested that the upper por- 
tion of the greensand series was of later age than the Cretaceous, 
a conclusion which he more fully elaborated at a later date. 

The second geological survey of New Jersey, organized in 
1854, under the direction of Wm. Kitchell, had as assistant 
geologist, George H. Cook, who a few years later became him- 
self State Geologist, a position he held for over twenty-five years, 
until his death in 1889. ~He devoted from the first much atten- 
tion to the greensands, and his classification of the strata has met 
with wide acceptance. It is elaborated in much detail in the 
Geology of New Jersey, published in 1868. The series of forma- 
tions as recognized by Professor Cook is as follows, beginning 
with the oldest: Plastic Clay, Clay Marls, Lower Marl Bed, Red 
Sand, Middle Marl Bed, Vellow Sand, and Upper Marl Bed. Subse- 
quently, Professor Cook considered that an unconformity existed 
between the Eocene and Cretaceous members of the Upper Marl 
Bed. 

There is no area in this country where the several formations 
have been studied more with reference to their own characteristics 


t Philadelphia Acad. Nat. Sci. Jour. Vol. 6, 1828, pp. 59-71. 


?Philadelphia Acad. Nat. Sci. Jour. new ser. Vol. 1, 1848, p. 129. Philadelphia 
Acad. Nat. Sci. Proc. Vol. 17, 1865, pp. 71, 72. 


3 Report of the State Geologist for 1883, pp. 13-19. 


THE GREENSANDS OF NEW JERSEY. 175 


and less with reference to the supposed similarity of faunas and 
deposits with other and particularly European horizons. 

The difficulties in the way of extended correlation are so great 
that for purposes of study it is often necessary to apply local 
names to the several formations of a particular district. There 
are, beyond a doubt, objections to the multiplication of names of 
geological horizons and already accepted terms should be employed 
as far as possible, but very frequently they prove to be inadequate 
for stratigraphical requirements. Such is the case in the New 
Jersey area. 

Outside of the major divisions of the geological column it is 
impossible to employ the terms of European authors. All such 
attempts have, upon critical examination, failed to stand the test. 
The lithological and faunal characteristics show such wide varia- 
tions that definite correlations of minor horizons are impossible. 
The geological formations of America must be studied first upon 
their own merits and only after a complete understanding of them 
has been gained can satisfactory comparisons be made with for- 
eign areas. A detailed correlation of the New Jersey formations 
with European will therefore not be attempted. 

Again the conditions under which the strata of the different 
portions of this country were deposited, are so varied that the 
same terms are not applicable over wide areas. The formations 
of the Interior are ina marked degree dissimilar from those of 
the Atlantic border, and even throughout the coastal plain very 
considerable differences are found in its various portions. Cor- 
relations of more satisfactory character can be made here than 
with foreign areas, but many obstacles debar the geologist from 
the full consummation of his task. It is possible to show in a 
general way the equivalency of the deposits upon the Atlantic 
border with those in the Gulf, the Interior, or on the Pacific coast, 
although in the case of individual formation$ such comparisons 
are of doubtful character. 

Dr. White* in his admirable essay upon the Cretaceous of 
North America, discusses very critically the evidence for the 


*Bull. U. S. Geol. Survey, 82, 1891, 273 pp. 


176 THE JOURNAL OF (GEOLOGY. 


correlation of the New Jersey greensands, but dees not attempt 
to separate the individual members of the series beyond the ref- 
erence of the upper member to the Eocene, as was also done by 
the writer? in’ his report. upon the’ Eocene. It is impossible 
however, to satisfactorily correlate this upper member of the 
greensand series with the Eocene elsewhere, and it is not known 
how much of that horizon is included init. It has been gener- 
ally thought to represent the Lower Eocene of other regions. 
Concerning the other formations of the greensand series there 
seems to be little doubt of their reference to the Upper Creta- 
ceous, although they probably do not include its earlier portions. 
Many of the same species have been found in the Cretaceous 
areas of the South Atlantic and Gulf States) “7Stanton= has 
recognized thirty-five species as identical in Alabama, eighty- 
six in Mississippi, and fifty-four in Texas. Some of the species 
which are very much restricted in the New Jersey area, appear 
to have a greater vertical range in the Gulf region. It is 
therefore very difficult to delimit equivalent horizons. It is 
not unlikely that a fuller knowledge of the formations may ren- 
der it possible to make more detailed correlations, but at present 
it is impossible. 

On these grounds, therefore, an independent classification of 
the New Jersey depositsis demanded. The objections to the use 
of lithologic terms have been already cited, as well as the 
grounds for employing the place names adopted. 


GENERAL CONCLUSIONS. 


The greensand strata of New Jersey constitute a conformable 
series of beds aggregating nearly 550 feet in thickness. During 
the Matawan epoch, when fully one-half of these deposits were 
being laid down, land-derived materials reached the sea in large 
amounts, frequently interfering with the formation of glauconite, 
which is much less prominent at this horizon than later. During 
the succeeding epochs the production of greensand was much 

*Bull. U. S. Geol. Survey, 83, 1891, 173 pp. 


? Bull. U.S. Geol. Survey, 82, 1891, p. 84. 


DLE GTREMINSAINDS OK NEW, JERSEY: 7 


more constant, although there were times when it became greatly 
reduced in amount on account of the advent of large amounts of 
sand and mud from the adjacent coasts. 

From the known conditions requisite for the srodhuatio’ of 
glauconite upon the bed of existing seas, and the possible 
position of the coast line in Cretaceous time, it seems likely 
that the greensands now outcropping at the surface were laid 
down from fifteen to thirty miles off the coast. Frequent 
changes of level no doubt took place, but the variations in the 
character of the deposits were probably quite as much due to 
fluctuations in the currents as to pronounced changes in the posi- 
tion of the coast line. . 

The marked thickening of the Matawan formation seaward, 
as shown by the well-boring at Asbury Park, is of interest as 
indicating the more permanent character of the deposition out- 
side the area of mechanical disturbance such as characterized the 
shallower portions of the Matawan sea floor. 

The alterations which have taken place in the exposed por- 
tions of the deposits are oftentimes widespread, and in the case 
of the indurated layers at the top of the Redbank formation 
have determined to a large extent the topography of the green- 
sand district. 3 

Many interesting problems are presented for further study, 
but it is hoped that this paper may contribute somewhat to a 
clearer understanding of greensand deposits in general, and those 
of the New Jersey area in particular. 


WILLIAM BULLOCK CLARK. 
GEOLOGICAL DEPARTMENT 
JoHNs HopxKINsS UNIVERSITY. 


IPISUE INVAINOIGS, Oe COIL, ISORMZONS), 


Tue Coal Measures of the Mississippi valley occupy an area 
of more than 120,000 square miles. They extend in an almost 
unbroken field from the western flank of the Appalachians on 
the east to beyond the Missouri river on the west. Separating 
the area into two somewhat unequal parts is the Mississippi 
river along the course of which are exposed older rocks. The 
Coal Measures may have been at one time continuous over the 
central portion, but the outcrops of the more ancient rocks along 
the borders of the Mississippi is probably not due entirely to 
unaided erosion but in part to slight folding, an anticlinal axis 
coinciding approximately with the line of the great river. 

The geological history of the eastern and western areas, 
which are sometimes called respectively the Central and the 
Western Interior coal fields, is probably similar, though in some 
particular phases there is a divergence which dates back prior to 
the close of the Lower Carboniferous. The northern portion of 
the Coal Measures west of the Mississippi forms a broad bay-like 
expansion opening to the westward. Beyond the Missouri river 
the strata are hidden from view by newer sediments. The most 
productive portion of the Western Interior coal field is a marg- 
inal zone extending from northcentral Iowa southeastward to 
northeastern Missouri, thence sweeping to the westward around 
the Ozark uplift into Indian Territory and continuing on into 
central Texas. The interior portion of the bay-like expansion 
of Coal Measures is as a general thing unproductive, though a 
few thin seams of coal do occur. 

Everywhere throughout the region the stratigraphical details 
present great simplicity, being almost free from the effects of 
orographic movements. The lithological characters of any one 


locality are repeated again and again in the same monotonous 
178 


INAMOTREN OM ACOA TE TTORLAONS,. 179 


succession. The faunal and floral features are practically identi- 
cal from one end of the great coal basin to the other. 

The greatest interest, economically and geologically, in the 
Carboniferous basin centers around the coal deposits. Their 
disposition perhaps comes first in importance, both from the 
standpoint of the operator and of the geologist. The subject is 
certainly one of wide-reaching import. 

There is now abundant evidence to show that the Western 
Interior coal field at the time of deposition was for the most 
part a broad, shallow basin opening to the westward into the 
great continental sea which then occupied most of what is now 
known as western North America. That the Coal Measures of 
the region were laid down during a period of gradual, prolonged, 
though often checked, subsidence is evidenced by all stratigraph- 
ical and lithological details, as well as by the characteristic 
faunal peculiarities. That the coal beds originated largely in 
coastal swamps of limited breadth but, with some interruptions, 
of very considerable length, stretching out near sea level for 
long distances and sending out minor extensions into the old 
rivers and estuaries is fully warranted by the facts disclosed 
everywhere. On the low, slowly sinking shores there prevailed 
at certain times a similarity of physical conditions especially 
favorable to coal formation. During these intervals unusual 
amounts of coaly material were allowed to accumulate and to be 
preserved in places, the period being preéminently one of coal 
growth, at least for a given province. The great stratigraphic 
plane marking each record may be appropriately termed a ‘Coal 
Horizon.” 

In stratigraphy, a geological horizon is a level recognizable 
over a considerable geographical extent, having a more or less 
well defined stratigraphical position, distinctive as to lithological 
features and characterized by a particular set of fossils. The 
term in a broad sense is almost equivalent to formation, and has 
been used as indefinitely. In its more limited meaning it is 
applied properly te a minor part or zone of the smallest strati- 
graphical unit having a commonly accepted specific name. Un- 


180 THE JOURNAL OF GEOLOGY. 


derstood in the same way, a ‘‘Coal Horizon”’ represents an even 
more limited expansion, where coal forming materials have 
accumulated. Practically it is one of the greater planes of sedi- 
mentation, marking a distinct episode in the deposition of a 
series of strata. Theoretically it represents not a phenomenon, 
but rather a set of conditions, a period during which the physical 
circumstances were similar over a considerable marginal portion 
of a geological province. From an economic standpoint it 
stands not for a continuous bed of mineral fuel, but a strati- 
graphical level where workable beds are more likely to occur 
than elsewhere, and where the coal is to be especially sought for 
in a wide belt fringing a great coal basin. It is not to be in- 
ferred, then, that the mineral is equally developed on a given 


BS OSR IS NAO Caio ys PE AIC a SF RIND 
ee Meroe oo SERS an 


Fic. 1. Coal Horizon at time of formation; parallel to shore line. 


horizon in all portions of this marginal border. In some places 
the accumulations of plant remains are much greater than in 
others; limited basins and troughs of unusual thicknesses are 
there found. Elsewhere the old vegetable materials are mea- 
gerly represented; only thin seams of coaly matter are there 
preserved. Wide intervals of sandstone and shale often separate 
adjoining basins, or ancient land elevations may cut off one area 
from another. (Figure 1). Yet, through all of the many irreg- 
ularities of deposition and subsequent deformation there are 
nevertheless discernible, certain leveis quite well defined at which 
coal beds are very much better developed than at others ; clearly 
marked coal horizons they are, broad in extent and capable, in 
the case of the greater ones under favorable circumstances, of 
being traced over a large part of a given Coal Measure province. 
The coal may not be present in a continuous seam over the whole 
border district and probably never is; but along much of the 


NATURE OF COAL HORIZONS. I8I 


margin of the coal horizon, which at one time must have stood 
near the sea level for a considerable period, are innumerable 
basins separated from one another perhaps, yet to all appear- 
ances formed contemporaneously. Now they may thicken into 
sharply defined lenticular beds; now thin out to mere films, or 
disappear altogether; and again further on they assume the 
form of extensive lens-shaped sheets. During deposition, as 
subsidence became too rapid or the sea too deep for the proper 
accumulations of vegetable material, sediments were carried in 
covering the plant beds. Or, if elevation ‘took place the old 
swamps, already shut off from free access to the sea, were sub- 
ject to the agencies of denudation and were partially or entirely 
removed. As favorable physical conditions again set in the 
same course of events might be repeated. 

In considering the relations of the different coal horizons to 
one another an approximate parallelism may be made out. Not 
a strict parallelism of the nature which Andrews’ claimed to be 
true in Ohio, and which Newberry? subsequently stated to be 
entirely unsubstantiated by facts, but an approximate parallel- 
ism in a broad way. 

There was apparently a germ of truth in the idea of the 
first named author, though he was probably unfortunate in the 
choice of a name for his theory. Moreover, none of his writings 
indicate that he understood the problem in the way that recent 
investigations reveal it. His statements all seem to show that, 
while he was manifestly on the right path, only one side of the 
subject had been presented to him, just as, quite recently, the 
question has been discussed from the opposite extreme. 
Andrews’ views are perhaps best expressed in the following 
paragraph taken from his paper? on the subject: 

“T have never found the slightest proof of the formation of 
a seam of coal over hills or high grounds. The parallelism of 
the seams, of which further mention will be made, forbids it. 


*Geol. Sur. Ohio, Vol. I, p. 348. Columbus, 1873. 
?Geol. Sur. Ohio, Vol. I, p. 169. Columbus, 1874. 
3Geol. Sur. Ohio, Vol. I, pp. 348-350. Columbus, 1873. 


182 THE JOURNAL OF GEOLOGY. 


So far as my observations go, I have never found 
an instance where two distinct seams of coal came together or, 
conversely, where a seam became divided and its parts continued 
to diverge for a long or indefinite distance. It is not uncommon 
to find, in a seam of coal, the proof that the coal marsh had in 
it local depressions, which were filled with sediments, making a 
soil on which new vegetation grew, and thus the seam shows 
two parts, separated by fire clay sometimes several feet thick; 
but in every instance when traced I have found the parts to 
reunite. The two parts never diverge indefinitely. From these 


Fic. 2. Stratigraphy of Coal Beds. 


statements we may infer a general law of parallelism. Such law 
is in harmony with the belief of the most careful observers, that 
our productive Coal Period was characterized by great quietness 
and freedom from violent local disturbances.”’ 

This describes the apparent condition of things in Ohio. The 
same with minor modifications and explanations may be regarded 
as according fairly well with the facts observed in the Iowa-Mis- 
souri coal field. 

On the other hand there are many who, with Newberry, have 
directly opposed any approach to the recognition of the paral- 
lelism of coal veins. Among the latest opinions on this side of 
the discussion is one expressed by Winslow," who in considering 


‘Geol. Sur. Missouri, Rep. Coal, pp. 28-30. Jefferson City, 1891. 


NATURE OF COAL HORIZONS. 183 


the stratigraphy of Missouri coal seams is led to believe that the 
different veins diverge from one another in a manner best 
explained by the preceding diagram, the dotted line representing 
post-Carboniferous erosion. (Figure 2). 

These conditions also accord in the main with the facts 
observed in all the Western coal fields. 

An attempt to harmonize the two seemingly very divergent 
and even contradictory theories is apparently fruitless. Buta 
more careful examination of the subject shows that the two the- 
ories are manifestly not based on facts taken from the same point 
of view, but from quite different positions. Andrews’ idea may 
be taken as representing a cross section of the coal bearing strata 
taken parallel to the general course of the shore ; Winslow’s a 
section at right angles. 

In districts where mountains are being elevated, orographic 
movements in the earth’s crust continue to be felt for long dis- 
tances from the line of maximum disturbances. Ifa great sea or 
an ocean occupies a region affected to a moderate extent by the 
oscillations, an extended shore line trends approximately with 
the axis of the mountain system, for the more important minor 
corrugations commonly run in similar parallel lines. The direc- 
tion of maximum change in the inclination of strata is therefore 
at right angles to the axes of the folds, and hence in a broad way 
perpendicular to the shore line. The direction of minimum 
change in tilting is, under ordinary conditions, the same as the 
axes, or parallel to the shore. Bearing these suggestions in mind 
geological cross sections, under favorable circumstances of exam- 
ination, would show a general parallelism of coal beds when 
made in one way; a decided tendency to non-parallelism when 
constructed in the other. 

Granting, then, an old, uneven land surface, such as is known 
to have existed in Carboniferous times in the upper Mississippi 
basin, with the waters of the sea and the marginal maritime flats 
gradually creeping inland, it would naturally be expected that in 
the case of any one of the marshy plains skirting the shores for 
any great distance there would be a very tortuous boundary on 


184 TTL Si OOTINATG OL NGHROROG NG 


the land side and a somewhat less sinuous line on the seaward 
side ; on the one hand were probably low hills and uplands send- 
ing out spurs here and there which cut off one marsh from 
another and often allowing long open stretches of low upland to 
reach out even to the waters of the sea itself; on the other hand 
were often narrow coastal plains rising scarcely above sea level, 
but, to a great extent, shutting off very effectually the saline 
waters from the swamps. Viewed areally, the productive por- 
tion of one of the great coal horizons is a wide irregular zone 
running in a tortuous course around a more or less extensive 
portion of the margin of a coal bearing basin included within 
the limits of a geological province. Examined at the present 
time coal horizons present, with all the irregularities of original 
deposition, subsequent change and deformation, a quite different 
aspect from the ideally perfect level of the ancient surface or 
zone which existed during the period of formation. In one 
direction, parallel to the shore, there is a series of minor. saucer- 
shaped basins strung along on about the same great stratigraphi- 
cal plane. They may rise or fall as the other strata change 
in inclination, They may be separated by wide stretches of 
sandstone or shale, or may come together in places. In the 
different basins the original vegetable materials in becoming 
compact shrink most in bulk in the middle, thus allowing the 
margins to remain considerably higher than the center. This 
is more noticeable in small basins than in large ones. Then, 
too, the fact that the direction of minimum movement in the 
changes of level was, as has been shown, parallel to the pre- 
vailing trend of the shore does not preclude even in this direc- 
tion a certain amount of tilting of the strata either by the rising 
or the sinking of one portion of the shore more rapidly than 
another; or by the passage of some of the minor folds in direc- 
tions not strictly harmonious with the general movement. 

When a new cycle of vegetable accumulation took place the 
coastal swamps would again spread out at sea level, but not neces- 
sarily on planes exactly parallel to the horizon previously formed, 
Horizons which were separated to very considerable distances by 


NANRCKE OF COAL HORIZONS. 185 


shales or other strata, probably are rarely exactly parallel to one 
another, or if so, the parallelism is purely coincidental. There 
are many causes which in places lead to the non-parallelism of 
the coal horizons. The original bottom of the sea may have 
been very uneven, as is well shown in the very irregular surface 
of the Saint Louis limestone on which the Coal Measures were 
1aid down. Or, in two different seams the inequalities may be 
great, the extremes often occurring in the same locality, and thus 
presenting a much greater apparent unevenness than really exists. 
Erosion or currents may have altered the position of the seams 
or parts of them. The top of the seams which were originally 
level became subsequently depressed in the center more than at 
the margins. There are also other causes tending to widen the 
seeming discrepancies. (Figure 3). 


Fic. 3. Coal Horizon as it now exists; parallel to shore line. 


In another direction, at right angles to the old shore, the 
minor basins along the different horizons may appear to show no 
tendency to parallelism at all. The approach to the parallel con- 
dition is inversely proportional to the amount of deformation 
occurring in the region at the time of the formation of the coal beds. 
Instead also of the seam being continuous for a considerable dis- 
tance across the coal basins, as may be inferred from Winslow’s 
graphic representation, the productive coal strata should be con- 
fined to a limited marginal area and the coal horizon would only 
extend into the interior as a great stratigraphical plane, not easily 
recognizable perhaps, nor with any of the mineral itself to mark 
iit (eb iteaunte 2) 

The conditions described apply particularly to the coal fields of 
Iowa and Missouri, where comparatively few disturbances of the 
strata have taken place. The relations are relatively simple. But 


186 THE JOURNAL OF GEOLOGY. 


in Ohio and Pennsylvania, as the mountains are approached, the 
structure increases rapidly in complexity, until in the highly 
folded and faulted districts attempts to follow out the original 
state of things may become utterly hopeless. 

The majority of the larger coal deposits of the Western 
Interior field may be considered then as having been formed in 
swamps skirting a great shallow gulf, the extent of the produc- 


Fic. 4. Coal Horizon viewed at right angles to shore line. 


tive portions of the different horizons being in a measure depend- 
ent upon the length of time the physical conditions were favora- 
ble to coal formation. Many short minor episodes doubtless 
existed between the larger ones, during which comparatively 
small accumulations of vegetable material took place. 

Another fact to be taken into consideration is that all the 
coal of the region was not formed in marine swamps, but that 
some of the minor basins were doubtless originally a very con- 
siderable distance from the sea, while certain others were formed 
where open sea conditions prevailed largely. A few seams also 
appear to have been formed as drift materials in estuaries at the 
mouths of streams. 

CHARLES ROLLIN KEYES. 


MWsWd, BIRIKAINS AS (COVE, MUSYAVSIONRUSS JON, TEU R US RDI 
HON MOM ACI CARBONE EROUS 
PROVINCE. 


CONTENTS. 


Introduction. 
Comparison with the Permo-Carboniferous of Kansas and Nebraska. 
Relations to the Texas Upper Carboniferous. 
Comparison with Foreign Upper Carboniferous. 
The Lo-ping Fauna, of China. 
The Salt Range Beds, India. = 
The Itaittba Fauna, Brazil. 
Classification and Age of the Arkansas Coal Measures. 
Provisional Classification. 
The Lower Coal Measures. 
The Upper Coal Measures. 
Paleobotanic Evidence. 
The Pacific Carboniferous Sea. 
Revolution in Devonian Time. 
The Carboniferous Sea. 
Upper Carboniferous in the West. 
The Pawhuski Limestone. 
Interchange of Life between East and West. 
Replacement of Limestones by the Coal-bearing Formations in Western 
Europe. 
Land Areas in the West. 
The Permian Pacific Ocean. 
The Triassic Pacific Ocean. 
Correlation table of the Arkansas Coal Measures with the Pacific Carboniferous 
Province. 


INTRODUCTION. 


Marine fossils of Coal Measure age were found by the Geo- 
logical Survey of Arkansas in eighteen places, fourteen in the 
lower division and four in the upper. These localities extend 
from Independence county westward to Indian Territory, and 

t From an unpublished report of the Geological Survey of Arkansas, by permis- 


sion of the Director, John C. Branner. 
187 


188 THE fOOKINA EVOL AGI OLOGN. 


give a total of 48 genera and 78 species, 31 species in the Lower 
Coal Measures, and 51 in the Upper, with 4 species common to 
both. 

It is not thought that this small number of species represents 
the entire fauna, or that only four species are common to the two 
divisions, for the collections were much too scattered and too 
meager to exhaust the possibilities. 

But the fauna is a poor one, such as one would expect to 
wander in from deeper waters, whenever a slight subsidence had 
made the shallow water a little more habitable. The fauna 
could not become well established, because the conditions soon 
reverted to their old state, and the inhabitants of the seas were 
forced to migrate or were exterminated. 

There is, therefore, no gradual transition here from the fauna 
- of the Lower Carboniferous limestone, since the presence of 
these fossils depends on the transgression of the sea on land 
areas, and the fossils of the Lower Coal Measures are just as 
different from those of the Lower Carboniferous as are those of 
the Upper Coal Measures. 

No successful division of the Coal Measures into zones has 
ever been carried out, and in the present state of our knowledge 
it cannot be done. This makes the correlation of distant local- 
ities difficult, since the vertical range of species in the Coal 
Measures is very little known. Therefore, the range of the 
species in Arkansas cannot be given any closer than the two 
great divisions of the Coal Measures. 


COMPARISON WITH THE PERMO-CARBONIFEROUS OF KANSAS AND 
NEBRASKA. 


The fauna of the Upper Coal Measures of Arkansas has a 
strong resemblance to that of youngest Paleozoic beds of Kan- 
sas and Nebraska, described as Permian by Professor Geinitz.* 

F. B. Meek redescribes this fauna,? and comes to the conclu- 
sion that the rocks in question are not to be referred to the Per- 

« “ Carbonformation und Dyas in Nebraska.” 


2 Final report U. S. Geol. Survey of Nebraska, etc., pp. 128 e¢ seg. 


THE ARKANSAS COAL MEASURES. 189 


mian, because he can find no paleontologic or stratigraphic break 
to separate them from the Carboniferous. He finds 16 genera 
characteristic of the Carboniferous, and 7 genera not thought 
to antedate the Permian in Europe, but associated with genera 
not thought tojjoceur later than the ‘Carboniferous. Micek: 
says that Husulina, which occurs in great numbers in the 
uppermost Carboniferous beds of Nebraska, is considered in 
Europe to be mainly if not exclusively a Lower Carbonifer- 
ous genus. In this, however, he was mistaken; his opin- 
ion dates from a time when most geologists were inclined to 
place all Carboniferous limestone in the Lower Carboniferous. 
But it is now known that the Carboniferous limestone occurs in 
the Upper Carboniferous about as often as in the Lower, and the 
Fusulina limestones of Sicily and Russia grade over into beds of 
undoubted Permian age. This is also true of corresponding 
beds in the upper part of the Carboniferous of Texas. In fact 
the /usulina beds are always either Upper Carboniferous or Per- 
mian, in eastern Europe and Asia, and nearly always in America. 

Although undoubtedly believing in continuity of life and 
formations, Meek seems to have based his reasoning on the old 
idea of catastrophies, since he thought that the absence of a 
paleontologic or stratigraphic break was a sufficient reason for 
calling the beds in question Upper Coal Measures rather than 
Permian. A large majority of the genera and species are char- 
acteristic of the Carboniferous, and this Meek thinks sufficient 
to offset the fact that several genera previously considered typi- 
cal of Permian? are present. 

In the Upper Coal Measures of Arkansas out of 51 species, 
there are 25 in common with the doubtful strata of Nebraska, 
and 6 other species are common to the Nebraskan Permo-Car- 
boniferous and the Lower Coal Measures of Arkansas, but have 
not yet been found in the Upper Coal Measures of the latter 


tPage 33, op. cit. 


2Tn the transactions of the Kansas Academy of Science, Vol. XIII., p. 38, Robert 
Hay announced that Professor H. S. Williams and Professor Tschernyschew had vis- 
ited the Fort Riley section, and agree that it was undoubtedly Permian. 


190 THE JOURNAL OF GEOLOGY. 


state. But of the genera mentioned’by Meek as being consid- 
ered not to antedate the Permian of Europé only two are found 
in the Arkansas strata, namely, Synocladia,* and Lima. 

There is therefore not sufficient reason for classing the 
Poteau mountain beds with the Permian, but their fauna, as well 
as stratigraphic position place them very high in the Coal 
Measures, since they agree in fauna and position with the Mis- 
sissippi valley Upper Coal Measures. These beds derive an 
additional interest from the fact that on Poteau mountain about 
one thousand feet of shales, in which no fossils were sought for, 
lie above the thin layer from which the entire collection was 
taken; thus the chances of finding true Permian beds in that 
region are very good. 


RELATIONS TO THE TEXAS UPPER CARBONIFEROUS. 


The only undoubted marine Permian in America has been 
described by Dr. C. A. White.? He finds the fauna of the upper 
Paleozoic beds of northern Texas, discovered by Professor W. 
F. Cummins, to be analogous to that of the /usulina limestone 
of Sicily, the Artinsk stage of the Ural mountains, and the 
upper part of the Productus limestone of the Salt Range, India. 
These strata all show that peculiar commingling of ordinary Coal 
Measure fossils with ammonite genera, such as VPopanoceras, 
Medhcotta, and Waagenoceras, which seems to be characteristic 
of open sea facies of the Permian. 

None of the characteristic ammonite genera were found in 
the Arkansas region, but nearly all the fossils found in the 
Arkansas Coal Measures are also foundin Texas. And in the 
Texas region nearly all the Permian species excepting the 
Ammonites were also found in the underlying Cisco division, 
which faunally and stratigraphically is the equivalent of the 
Upper Coal Measures of Arkansas. 

Gomiatites (Gastrioceras) baylorensis White is represented in 

t WAAGEN has shown, in Pal. Indica, Salt Range Fossils, I. Productus Limestone 


Fossils, p. 802, that Syzocladia is not found in America, the species described by 
Swallow as Synocladia biserialis being a Septopora. 


2 Bulletin 77, U.S. Geological Survey. 


THE ARKANSAS COAL MEASURES. IQ! 


Arkansas by the closely related species Gomatites globulosus Meek 
and Worthen. 

Orthoceras rushense McChesney, is found in both areas; the 
Endolobus is possibly the same in both, or closely related; Auom- 
phalus subquadratus Meek and Worthen, is common to both; 
Bellerophon crassus Meek and Worthen, is found in both areas ; 
Pleurophorus sp. is probably the same in both regions. 

Nearly all the Upper Carboniferous species of Texas and Arkan- 
sas are also found in Illinois, Iowa, etc., in beds that have never 
been thought to be other than Coal Measures. We are therefore 
safe in concluding, that while some of the beds in western Arkan- 
sas are very high up in the Coal Measures, none that belong above 
them are as yet certainly known, and the Poteau mountain syn- 
cline, across the line in Indian Territory, is the only place where 
there is any likelihood of finding Permian deposits. 


COMPARISON WITH FOREIGN UPPER CARBONIFEROUS. 


The Lo-ping fauna.—The descriptions of the fossils of the 
Lo-ping district of China, by Professor E. Kayser," throw great 
light on the relations of the American Carboniferous faunas to 
those of Asia. Near Lo-ping, in eastern China, are found in 
strata overlying the coal-beds, numerous marine fossils of Upper 
Coal Measure age. Kayser has described 55 species, 10 not spe- 
cifically identified, 15 cosmopolitan species, and 11 forms that 
are typically American, and belong chiefly to the Upper Coal 
Measures. 

The 15 cosmopolitan species are also nearly all found in the 
American Upper Coal Measures, so that of the entire Lo-ping 
fauna nearly all the species are either found in America, or they 
have their nearest relatives there. The two regions belong to 
the same zodlogical province, the Pacific Carboniferous sea. 

Many of these species that are very common in America and 
Asia are unknown or rare in Europe, which fact would tend to 
prove a connection with Asia by water, and the separation of the 
European and the American Upper Coal Measure deposits by a 
land barrier. 


tRICHTHOFEN: “China,” Vol. IV. 


192 ; THE JOURNAL OF GEOLOGY. 


The Carboniferous plants collected by Baron von Richthofen* 
numbered about 40 species and were nearly all identical with 
European Carboniferous plants. The natural inference is that in 
those times Asia was connected with Europe by land, and that 
the sea opened out to the east. 

Professor J.S. Newberry” described a small collection of Car- 
boniferous plants from China, and found nearly all of them to 
belong to well-known European species. This is in perfect agree- 
ment with the conclusions drawn above. 

The Salt Range beds—In the Salt Range, in northwest India, 
are found Upper Carboniferous deposits, some of which resemble 
those of Lo-ping, China; and the Lower Productus limestone of 
India is probably of about the same age as the beds of Lo-ping, 
and the western American Upper Coal Measures. These deposits 
and their fauna are described by Professor W. Waagen,3 and in 
the volume on “Geological Results” he draws parallels between 
the faunas of the upper Paleozoic in different countries. Many 
of the American species that are found at Lo-ping are also found 
in the Salt Range Lower Productus limestone. This same type of 
Carboniferous is found in Sumatra, where it has been described 
by Ferd. Roemer,‘ and on Timor, where it was described by E. 
Beyrich.s This is the furthest southward that the Indian or north- 
ern type of Upper Carboniferous is known, and indeed the deposits 
of Sumatra and Timor begin to show already a greater affinity 
for the Australian or southern type of Carboniferous. 

Waagen® divides the Carboniferous into two types, the north- 
ern or Asiatic, and the southern or Australo-African. The north- 
ern type is found in western Europe, Russia, the Himalayas, China, 
the Arctic regions and North America. The southern type is 
developed in South Africa and Australia, and extends into Penin- 


© RICHTHOFEN: China, Vol. IV., Abhandlung 9, Dr. A. Schenk. 

2 American Journal of Science, Vol. 126, 1883, pp. 123 ed seg. 

3 Paleontologia Indica. Salt Range Fossils. 

4Paleontographica, Vol. 27, 1880. 

5 Abhandlungen der Berliner Akademie der Wissenschaften, 1864. 


6Salt Range Fossils, Geological Results, p. 239. 


THE ARKANSAS COAL MEASURES. 193 


sular Indiaand Afghanistan. Brazil probably belongs to this type, 
but is to a certain extent transitional. 

The Itaitiba fauna.—A comparison of the Upper Carbonifer- 
ous fauna of Itaittiba, Brazil, as described in part by Professor O. 
A. Derby,' shows that of 27 species of Brachiopoda, 12 are iden- 
tical with American forms, although most of these are cosmo- 
politan. The genus Sérophalosia is common in these beds, and as 
Professor Derby? says, the species shows affinity with the Permian. 
Many of the new species described by Professor Derby are closely 
related to the European forms. Waagen? says that the beds of 
Itaittiba are of the same age as the Middle Productus limestone of 
India, that is of the Permo-Carboniferous transition beds. The 
Brazilian Strophalosia is closely related to Australian species, indi- 
cating a closer connection with the Australian or southern Car- 
boniferous region than with the Pacific province. Hence we infer 
that the Brazilian deposits may after all belong to the Upper Coal 
Measures, and that the difference between them and the northern 
Upper Coal Measures may be geographic instead of geologic. 


CLASSIFICATION AND AGE OF THE ARKANSAS COAL MEASURES. 


Provisional classification.—For the sake of convenience, the 
Coal Measures of Arkansas have been provisionally classified by 
the Survey as Upper or Productive, and Lower or Barren Coal 
Measures. This division is not based on any paleontologic or 
stratigraphic break, but merely on the occurrence or non-occur- 
rence of coal. 

The divisions that are recognized in Pennsylvania could not 
be recognized in Arkansas, but the strata of the two regions are 
correlated as far as possible with the scanty data now at hand. 

The Lower Coal Measures —Of the age of the Lower Coal 
Measures we have only stratigraphic evidence, their position 
above the limestone of the Lower Carboniferous, and below the 
coal-bearing beds of the Lower Coal Measures being unmistakable. 


‘Bulletin Cornell University, Vol. I., No. 2. 
2Op. cit., p. 60. 


3Salt Range Fossils, “Geological Results,” p. 207. 


194 THT. JOURNAL ORANGE OLOG Ve 


But their known fauna and flora have been too limited and 
too indecisive to enable us to correlate subdivisions with those 
of other Carboniferous areas, since collections have been made 
in but few places, and these chiefly in sandstones, where the 
preservation of fossils is usually unsatisfactory, and their deter- 
mination uncertain. 

But the Lower Coal Measures correspond in a general way 
to the Strawn and the Canyon divisions of Texas, the Pottsville 
conglomerate series, the Lower Productive Coal Measures, and 
part of the Lower Barren Coal Measures of Pennsylvania. 

The Upper Coal Measures—The Arkansas Upper Coal Meas- 
ures correspond to the lower part of the Cisco of Texas, and 
belong just at the top of the true Carboniferous, and below the 
transitional Permo-Carboniferous or Artinsk stage, to which latter 
age the uppermost Cisco beds of Texas, with Asumonites (Popan- 
oceras) parkeri* Heilprin belong. These may be the equivalents 
of the Poteau mountain marine beds. 

The lower Permo-Carboniferous strata of Kansas and Nebraska 
are probably also to be correlated with the Artinsk? stage, although 
Waagen classes the entire series with the ammonite-bearing 
beds of northern Texas, described by Dr. C. A. White in Bulle- 
tin 77 of the U. S. Geological Survey. The latter Texas beds, 
however, belong above the Artinsk stage, and in the true Per- 
mian, and are probably of the same age as the middle division 
of the Middle Productus \imestone of the Salt Range. 

Waagen, in “Salt Range Fossils, Geological Results,” p. 
238, gives a comparative table, showing the relationship of the — 
upper Paleozoic strata all over the world. While the position 
assigned some of the American deposits does not agree with 
that accepted by most American geologists, still the table is use- 
ful for comparison, and it has been freely used in compiling the 
comparative table at the end of this paper. 


«This horizon is at the top of the Cisco, and above the horizon of Gondatifes 
Marianus. 


2 KARPINSKY : “ Ammoneen der Artinsk-Stufe,” p. 92. 


3Salt Range Fossils, Geological Results, p. 204. 


THE ARKANSAS COAL MEASURES. 195 


The beds of Poteau mountain, Indian Territory, are probably 
of the age of the Lo-ping strata of China, while the yellow shales 
of Scott county, Arkansas, Township 1 N., Range 28 W., Sec- 
tion 4, southeast quarter of southeast quarter, are probably of 
the age of the Upper Carboniferous limestone of Moscow, and 
the west slope of the Ural Mountains, if we can judge by the 
occurrence of Gastrioceras marianum and Pronorites inthem. This 
would make them older than the Poteau mountain shales, which 
is very likely the case. 

Paleobotanic evidence.——-Our knowledge of the paleobotany of 
the Coal Measures of Arkansas has been up to the present time 
very limited, depending almost entirely on the publications of 
Lesquereux, in the “Second Annual Report of a Geological 
Reconnaissance of the Middle and Southern Counties of Arkan- 
sas,’ 1860, and in the Second Geological Survey of Pennsyl- 
vania, Report of Progress, P, ‘Description of the Coal Flora of 
the Carboniferous Formation in Pennsylvania, and throughout 
the United States,” 1884. 

The joint monograph of H. L. Fairchild and David White, 
on the ‘Fossil Flora of the Coal Measures of Arkansas,’’* 
throws much new light on the stratigraphic and regional dis- 
tribution of species, and has been of material aid in correlating 
the Arkansas strata with those of other regions. They prove 
that all the Coal Measure plants* published from Arkansas 
belong to the horizon of the Upper or Productive Coal Measures. 

The Van Buren plant bed is thought, from paleobotanic evi- 
dence, to belong above the horizon from which most of the coal 
of Arkansas is obtained, that of the Ouita coal, and this agrees 
with the evidence given by the stratigraphy and the marine fos- 
sils. The Van Buren plant bed occurs below the Poteau moun- 
tain marine beds, and above those in Sebastian county, Town- 
ship: oa Nance 2 VE Section 12; and these latter marine 
beds occur above the horizon of the Ouita coal. 


* An unpublished report of the Geological Survey of Arkansas. 


2The work of the Survey shows that the plants described by Lesquereux from 
Washington county as Sub-Conglomerate belong to the Lower Carboniferous. 


196 UIEUE JROGISINAWL, (QUE GIB OWL OG 3A, 


The Poteau mountain marine beds are of about the same age 
as the Wyoming valley limestones* of the Upper Productive Coal 
Measures of Pennsylvania, and these belong below the Dunkard 
creek series of the Upper Barren Coal Measures. The Dunkard 
creek? beds have lately been proved by Professor I. C. White to 
be of the same age as the Permian of northern Texas, on the 
basis of plant remains that also occur towards the top of the 
Wichita series of Texas, in which marine Permian fossils3 have 
already been found. 

But the paleobotanic evidence aids in establishing the age of 
the Upper Coal Measures only; plants are not reported from 
any horizons of the Lower Coal Measures, although they are 
known from a few localities. 

_ Owen‘ mentions Stgmaria ficoides as occurring at Patterson’s 
mill~near Bee Rock, on Witte Wedaniver,) White countya sin 
August, 1892, a few plants were found by the Survey in the Bee 
Rock sandstone, near the base of the series and below most of 
the marine fossils, but none of these could be identified. 

General D. McRae, of Searcy, informed the Survey that in 
Township 7 N., Range 7 W., Section 4, in White county, were 
found shales containing numerous Lefidodendra and ferns. These 
shales are above the Bee Rock sandstones. 

In a well at Dr. Griffin’s, Township 5 N., Range 10 W., Sec- 
tion 5, near El Paso, White county, specimens of Lepidodendron 
were collected by Dr. J. C. Branner, in micaceous flaggy sand- 
stone, thought to be of the same age as the shales of Searcy. 
About fifty feet above the flaggy sandstone was found a thin bed 
of coal, and thirty feet higher was another coal bed with 
numerous ferns and Calamites in the overlying shales. 

C. S. Prosser’ mentions plants supposed to be of Lower 

‘Second Geol. Sur. of Pa., An. Rep., 1885, pp. 437-458, C. A. ASHBURNER 
and A. HEILPRIN, “Report on the Wyoming Valley Limestone Beds.” 

2 Bul. Geol. Soc. America, Vol. III., p. 217. 

3 Dr. C. A. White, Bulletin 77, U. S. Geological Survey. 

4Second Geol. Recon. Ark., Vol. I., p. 68. 

5 Ark. Geol. Survey, An. Rep., Vol. III., 1890, p. 423. 


DHE ARIGANSAS COAL MEASURES. 1O7 


Carboniferous age, from Shinall mountain. In quarries in the 
sandstones of Big Rock, near the city of Little Rock, are found 
plant remains of indeterminable character. The stratigraphy of 
the Survey places both localities in the Lower Coal Measures, 
and probably above the fossiliferous sandstones of Bee Rock, on 
Little Red river. 

THE PACIFIC CARBONIFEROUS SEA. 


Revolution in Devonian time.—In Paleozoic times there have 
been many revolutions and alternations of continents and seas, 
and consequent readjustment of their inhabitants to new sur- 
roundings. One of the greatest of these was that which broke 
up a large zodlogical province, and put in direct connection 
regions that before were separated. 

Dr. A. Ulrich? has shown that in lower and middle Devonian 
the faunas of Bolivia, Brazil, the Falkland Islands, and South 
Africa were very similar to those of North America, and that 
they were very different from the faunas of Europe and Asia. 
This state lasted until the end of the middle Devonian, when 
the revolution began. Professor H. S. Williams? has shown that 
with the beginning of the upper Devonian in America there 
came in a fauna, many species of which were not the direct 
descendants of those immediately preceding them. This new 
fauna was, however, closely related to forms known in Europe 
and Asia, but unlike those of the southern regions. 

Professor Williams? afterwards elaborated this theory, and 
followed out closely the changes that were inaugurated towards 
the end of the Devonian. The culmination of these changes 
produced the Pacific Carboniferous sea. 

The Carboniferous sea—From chapter V., in Suess’ “ Antlitz 
der Erde,” Vol. II., we get many valuable suggestions as to the 
outlines of the Pacific Carboniferous ocean. The Subcarbonifer- 

*Beitrage zur Geologie und Paldontologie von Siidamerika, I., “ Palaozoische 
Versteinerungen aus Bolivien.” 

? Bull. Geol. Soc. America, Vol. I., “‘ The Cuboides Zone and Its Fauna. 


3 Proc. Amer. Assoc. Adv. Sc., 1892, Section E, Address, “ The Scope of Paleon- 
tology and Its Value to Geologists.” 


198 THE JOURNAL OF GEOLOGY. 


ous was the time of greatest transgression of sea over the pres- 
ent land areas, while the sea in which the Fusulina beds of Europe 
and America were formed was more circumscribed. 

The Waverly group when traced towards the west gradually 
takes on the character of deep water formations ; it is persistent 
through Nevada and California, * and is known, from unpublished 
investigations, to have a similar fauna in these two states. The 
Waverly probably persisted much longer in the west, than in the 
east, for in northern Missouri C. R. Keyes’ has observed that 
in the midst of an undoubted Burlington fauna a well marked 
Kinderhook or Waverly fauna reappears. This he explains by 
Barrande’s theory of colonies. It is probably an incursion of 
the inhabitants of a deeper western sea, where the Waverly had 
persisted longer, into the shallower eastern waters. The work 
of the Geological Survey of Arkansas shows that a similar phe- 
nomenon occurs in that state. The Fayetteville shale, which is 
probably of Keokuk age, contains a fauna that differs markedly 
from those of the limestones above and below it. An unpub- 
lished report by Professor Henry S. Williams shows the occur- 
rence in the Fayetteville shale of several species that occur in 
a doubtful upper Devonian or lower Carboniferous black shale 
in the White Pine district, Nevada. Along with these Devonian 
or Waverly species occur others that belong much higher, as 
Productus semireticulatus, and Goniatites conf. sphericus. Below the 
Fayetteville shale is the Boone chert, which at the base contains 
a decided Burlington fauna, and at the top probably belongs to 
the Keokuk. This has been observed in so many places that 
there is no possibility of mistake in the sequence of the strata. 

We have therefore in Arkansas an incursion similar to that in 
Missouri, except that in Arkansas the incursion came consider- 
ably later. This is evidence that somewhere in the west the 
Waverly fauna persisted throughout the Burlington, and at least 
a part of the Keokuk. This is in accordance with the phenome- 
non described by Professor C. D. Walcott in Monograph VIII., 

t Zoe, Vol. IIL., p. 274; Proc. Calif. Acad. Sci., Oct. 17, 1892. 


2 American Journal of Science, December, 1892, p. 447. 


THE ARKANSAS COAL MEASURES. ° 199 


U. S. Geological Survey, from the Eureka district, Nevada, where 
a Waverly fauna occurs 3000 feet above the base of the Carbon- 
iferous formation. The same thing has been observed by the 
writer in the Carboniferous of Shasta county, California. 

The Lower Carbaniferous limestones can be traced all 
through the west and the Mississippi Valley, to the base of the 
Appalachian Mountains, where they are replaced by conglomer- 
ates and other coarse sediments. 

Upper Carboniferous in the West——Of the Upper Carboniferous 
all that we know west of Indian Territory takes on a decidedly 
marine character, containing thick beds of limestones. 

There are however some thin beds of coal in Texas, and 
some carbonaceous seams with a few land plants in New Mexico 
and Nevada. The coal in Texas was probably deposited near 
the southern shore line of the Carboniferous sea, and the carbon- 
aceous seams in the far west probably belong to insular areas. 

The fossils described from the Western Carboniferous are all 
marine, with the slight exception that Walcott’ mentions a few 
specimens of pulmonate Gasteropoda, that were found along with 
brachiopods, corals, and land plants, evidently washed in from a 
distance, since no terrestrial Carboniferous deposits are known 
near the Eureka district. 

The Pawhuski limestone.—In the eastern part of Indian Terri- 
tory are found large deposits of coal in the Upper Coal Measures, 
but further west the same horizon is represented by marine lime- 
stone. In 1892 Mr. H.-C. Hoover, of the Geological Survey of 
Arkansas, found at the government lime-kiln, three miles north- 
west of Pawhuski, Oklahoma Territory, Osage Agency, a bed of 
massive limestone about 100 feet thick, lying horizontally on 
heavily bedded sandstones. The limestone is fossiliferous, but 
the sandstones are not. The fossils collected were placed at my 
disposal, and on examination they proved to be: 

Spuifer cameratus Morton. 

Athyris subtilita Hall sp. 

Productus semwreticulatus Martin sp. 

™Mon. VIII., U. S. Geol. Survey, p. 262. 


200 THE JOURNAL OF GEOLOGY. 


Productus nebrascensis Owen. 

Productus longispinus Sowerby. 

Streptorhynchus crassus Meek and Hayden. 

These are plainly of Upper Carboniferous age. The limestones 
cap the hills in that region, and spread over a great area, but fos- 
sils were collected at this place only. 

Interchange of life between East and West—The many beds 
of marine fossils in the Productive Coal Measures are simply trans- 
gressions from the western sea, and reach no further east than 
Pennsylvania and West Virginia. The Appalachian system was 
the western border of the ancient Atlantis’ which separated the 
European from the Pacific waters, while the great Indo-Austra- 
lian? continent bounded the Pacific ocean on the south. This 
ocean must have stretched from the American Coal Measures to 
eastern China, the Salt Range in India, the Ural Mountains on the 
borders of Russia, and into the Arctic regions, for we find related 
faunas in all these places. Whatever we have of western Euro- 
pean Coal Measure species must have migrated from this direc- 
tion, since on the east there was no direct communication with 
European waters. An example of this is Productus giganteus’ 
Martin, which is common in Europe, and is found in the Lower 
Carboniferous of the McCloud river, Shasta county, but is not 
found east of that place, unless P. datessimus Sowerby, from Mon- 
tana, west of the main chain of the Rocky Mountains, be an 
equivalent. 

On the other hand, many species seem to be confined to, or 
characteristic of, this ocean; among them may be mentioned 
Productus cora Ad’ Orbigny, which Waagen* says is not found in 
Europe, its nearest representative being Productus riparius Traut- 
schold; it was however first described from South America. 

Goniatites marianus Verneul is found in the Artinsk region of 

‘Suess: Antlitz der Erde, II., p. 17. 

2Suess: Antlitz der Erde, II., p. 316. 


3See Annual Report U. S. Geog. and Geol. Surv. Terr. 1883, Part I., p. 132, and 
Bull. Geog. and Geol. Surv. Terr. Vol. Il., No. 4, p. 354. 


4 Pal. Indica, Salt Range Fossils, Brachiopoda, p. 677. 


THE ARKANSAS COAL MEASURES. 201 


the Urals, probably in Sumatra, and in Arkansas. The genus 
Pronorites, while found in western Europe, is rare in it, and is much 
more common in the Pacific region. Pvonorites is found in the 
Artinsk region and in Arkansas, while the ammonite genus 
Medthcottia, the direct descendant of Pyonorites, is found in the 
Permo-Carboniferous strata of Sicily, the Urals, the Salt Range, 
and Texas. 

It is impossible to suppose that the same genus and species 
originated at different localities, and since we have both ancestors 
and descendants in places so widely separated, we can only sup- 
pose that there was free interchange of life between those places 
at that time, or in other words an open sea, on the borders of 
which these fossiliferous deposits were laid down, and through 
which the cephalopods and other marine animals could migrate. 

Replacement of Limestones by coal-bearing formations in western 
ELurope.-—On tracing the Upper Carboniferous deposits of the Ural 
region towards the west, we find the limestones thinning out, and 
the Coal Measures and Culm formations taking their places; we 
find also that the transgression of marine on terrestrial deposits 
takes place from the east, just the reverse of what is seen in 
America. ; 

Land areas in the West.—lIt is not thought that the Pacific 
Carboniferous sea was an unbroken expanse of water in western 
America; on the contrary there are many evidences of large iso- 
lated land areas and archipelagos. 

Dr. Joseph Le Conte* has argued that the Basin Range, during 
much of Paleozoic and Mesozoic time, was a continent, off the 
western shores of which the sediments that afterwards became the 
Sierra Nevada and Coast Range were laid down. Clarence King? 
thought that the great thickness of Paleozoic littoral deposits in 
the Great Basin region proved the existence of a large body of 
land further west; he thought that the eastern shore of this con- 
tinent was in Nevada, and east of this stretched the Carboniferous 
sea, which covered all but the island chain of the Rocky moun- 

*American Journal of Science, III., Vol. 16, p. 108. 

2U. S. Geol. Explor. Fortieth Parallel, Vol. I., p. 534. 


202 GEOR OU INAUL (QUI (CSB OIL OG IZ 


tain region. King* further concluded that the Carboniferous in 
California, west of the old shore line, indicated shallow bays that 
permitted the western extension of the upper Paleozoic deposits, 
while the bulk of them was stopped by the bold coast. There 
are evidences of land areas in the Rocky mountains, Wahsatch 
mountains, New Mexico, and Nevada, but from the facts now 
known it seems more probable that these were large islands or 
archipelagos, rather than continents. 


THE PERMIAN PACIFIC OCEAN. 


The outlines of the great western ocean can be traced in 
Permian times also, but with much more circumscribed limits. 
Open sea deposits of this age are known in Texas, in the Salt 
Range, on the west slope of the Urals, on the island of Sicily, 
and in scattering places in central Asia. In all these the genera 
are nearly the same, except that the Avcestes types are confined 
to the more southern regions. This similarity indicates plainly 
a connection of these deposits. 

Suess? argues that the open sea Permian fauna wandered in 
from the south, and that the Mesozoic types of Azmonites were 
foreign to the northern regions. 

Karpinsky,3 on the contrary, holds that they were autochtho- 
nous, at least in the Ural region, since he could trace the descent 
of all the Ammonites, except the Popanocerata from Gontatites that 
were found in the underlying Carboniferous. 

As has been already mentioned, the ammonite genus Medh- 
cottia is not a foreigner on this side of the Permian Pacific ocean, 
because its ancestor, Pronorites, is found here too. 

The Triassic Pacific ocean—Our knowledge of the Triassic 
Pacific ocean is based on the work of Mojsisovics, ‘‘ Arktische 
Triasfaunen.’’4 We find that in this period the American part of 
the great western ocean has mostly become land, and only on 


TOp. cit., p. 535. 
2 Antlitz der Erde, II., p. 316. 
3 Ammoneen der Artinsk-Stufe, p. 86. 


4 Mem. Acad. Imper. Sci. St. Petersbourg, Tome 33, No. 6. 


SS NS ee eae. 


THE ARKANSAS COAL MEASURES. 203 


the western border of America do we find marine Triassic beds, 
in Nevada, California, Idaho, and along the Sas region in 
scattering places from Alaska to Peru. 

These deposits, with similar fauna, can be traced on the 
other side of the Pacific, from New Zealand, Timor, New Cale- 
donia, to Japan and Siberia. This sea stretches out on one side 
over the Himalayas to the eastern Alps, forming what Neumayr? 
calls the ‘‘central mediterranean sea.’’ On the south side the 
sea stretched up to Spitzbergen, but did not reach the Atlantic 
region. The Triassic was a continental period for the greater 
part of the present continents. ? 

After the Trias the outlines of the western ocean had changed 
entirely, and no resemblance to the original boundaries can be 


traced. JAMES PERRIN SMITH. 
STANFORD UNIVERSITY, 
CALIFORNIA. 


* Denkschrift Wiener Akad., 1885, “ Die Geographische Verbreitung der Juraform- 
tion.” 


? Suess: Antlitz der Erde, IL, p. 147. 


. 


7, 


LTE WO OLINATC LO Fin G5 OLGOGH, 


204 


~ 
2 50 
= Za 
Loh@Z) Sy 
cq) Wuoseunry | euoisawry auoj}sowry S Do 2 i 
a sno sno sno auojysowry BD 25 
3) -deyruoqiey | -1ayruoquea S91I9G -rayTUOqies snolayluogies 2 Bo 
a IOMOT MoT jyuNYyD yoneyy| JsMoT UOISIAIG, pusg TOMO. | |i ci siento Wo} SMELT] Salone) AN CoTgnRAD) BeMNC AL le) ah 
IS Oz ie (e) 
ny B os s at ede) & ee. | os - . =, leotooocoogcte spag weg “oy eeg ‘Aorvas 9 ro) 
SPURNS Bere We J 3 Ses |e ere a enced spag ures, “yoy eaq ‘Aoreag | 2 > 
B CBG o:- To SAR ay eee ee [Pose sped suefg “Gunoy aya ‘osed ta | 25) 5 
oad Ss Zo $.8 COS. speg juelg ‘Ajunog ryse[ng ‘yoy sig | a= Zz 
(Oe Si Qt Oe os Bea [fetes erate Tee s[issog Pall Werle 
aS 4 a on By 4 3 9 Ue, YIM 31D duO}sT[TJA Ayun0D AemuoD | c Sia 
nd si eala! A ity alps. = =  WecénonsoaoogopeonnoGs speg euTe A, UO [OLY is ca 
y BO 2 zoe y $ , "| Sa 
ael| eB Sone Js —| 22 
oo 7 ie) pe 
a 99 oz arse 9 Ole | pestarseetereisrss SIILLOUIAT PUY SHUDIADUL ‘ ae 
seh iEe om 229 ID, Cig BU |sagzgv7u0y YM spag ‘AyunoD 09S ‘sajog | Zo 
» 3 o po. 7 (o) ho a sataats Ly a rs) 
5 () a a 5 a2< is = QYEi aS =| g aS este eee ars sjue[g YA uoz0F [kod BING | Zs 
as SS e a o 5c 33 aS 8 % Ss ae Bio cnoIg id nC OOOO Oicrordicic speg sulle yy, YIWIS 1104 a AS | 
a 3 77) ( n noes ae Aw 35 po eleteh-ekoPeleistadeleistelanataiatn Tens spegq jue[q uaing ue, a 2 
n| * lelquieazeaon| durd-o7 jo |g AEH Oe 5 i tee 5 Si i [scloryks aleictecss spog dUuliey] UleyUNOy nvaj}0g z 2 
“ssny ‘YMON|Speg eure yy} B mm | #7 Ou n $ fa ' 
: aD speg a sped 
sped S) [ eaEis podojeydad Bf thaysog Seah ee) 
LER fer eA vrey og 9 is: B 8 | svsasoungog d ae} 
gy oe ae : 
a8 UvIULIag Kad Bok "o}0 ‘sv499 S 
& & || evwonsoy ae BSS | -ouasvv yf = 
as) oe Z § |svsaz0ungog > 
ats zo Sm | ‘wzg0227 pay Z 
gee ee BS mya 
Ros BG |Sareg eryor Ay 
n 
a vIS 
any, VIGN] SS lw Si s1uva ye para SVX4], Gee ga *SVSNVNUY 
HLAOS vISSOy GEL -IASNNAg_ | IddISSISSIJL NVIGN] 


ADNIAOUd SNOMAAINOPAVD DIAIOVd 
AHL HLIM SVSNVXUV AO SAYNSVAW TVOD AHL AO ATAVL NOILVTAAAOD 


PSEUDO-COLS:: 


THE French term col is gradually coming into use to signify 
low passes or saddles on the watershed between drainage sys- 
tems. Its use is very convenient in the discussion of reversed 
or diverted drainage, particularly that caused by the intrusion of 
glacial or igneous obstacles. It not infrequently happens that, 
when a glacier enters the lower part of a drainage basin, it ponds 
back the waters, and causes them to pass over such a col into a 
neighboring basin. Sometimes the valley becomes permanently 
filled with glacial wash and morainic debris to such an extent as 
to cause the diverted stream to retain its new course after the 
retreat of the ice. In such cases the stream, in subsequently 
deepening its valley, forms a trench across the col, which grad- 
ually takes on the form of an ordinary valley. In time the col 
is only represented by a constriction of the new valley and by 
certain residual features of the old topographic configuration. 
The floor of the trench across the col obviously assumes the 
slope of the new stream that caused it, and has its highest part 
on the up-stream side of the former col. As the trench is cut 
deeper and deeper, the highest point in the rock floor is gradu- 
ally carried up stream. It may, in this way, be transferred some 
distance from the original col and may thus become entirely 
disassociated from its peculiar topographic relations. If, after 
this has been done, another glacial invasion takes place and the 
valley becomes again filled with glacial wash to some considerable 
height, the transferred summit of the rock floor is liable to lose 
its obvious connection with the old col and may perhaps seem 
to be associated with new and misleading topographic surround- 
ings. If, in such a case, the valley debris is penetrated by wells 
at only a few points, and the investigator ascertains thereby only 

* Presented in substance before the Geological Society of America at Boston, Dec. 


31, 1893. 
205 


206 THE JOURNAL OF, GEOLOGY. 


imperfectly the nature of the trench and the location of the rock 
summit in its buried floor, he is liable to mistake this obscured 
rock summit for a true col. It is, in fact, not a col at all in any 
proper sense. It never has been a watershed, and has never 
performed the functions or sustained the relations of a true col. 
As there is frequent occasion to refer to this phenomenon in the 
discussion of certain regions of reversed drainage along the 
border of the ancient glacial formations, I propose for it the 
distinctive name pseudo-col. The nature of the phenomenon has 
been more or less distinctly recognized by many geologists. 
The purpose of this note is merely to bring it forth into more 
definite recognition and to supply it with a convenient name 
which may be used in lieu of the cumbersome periphrastic 


phraseology now required. 
i T. C. CHAMBERLIN. 


NOGEVON iE EN GIErS Eis QUIN AIa Nain @is 
SCHUPPENSTRUKIUR: 


In a paper entitled ‘On the geological structure of the 
Housatonic valley lying east of Mt. Washington” (JOURNAL OF 
Groxoey, Vol. I. No. 8), I proposed the term (p. 791) weather- 
board structure as an equivalent of Suess’s term Schuppenstruktur 
to describe a structure caused by a series of small compressed 
overfolds finding relief through dislocation, and resulting in the 
production of a parallel series of overlapping plates. Mr. Ber- 
nard Hobson, of Manchester, England, has suggested to me that 
the term wnbricate structure would be better because of its Latin 
derivation and its use in botanical literature. The two terms are 
practically identical as regards the idea conveyed, and though 
the term first suggested would perhaps give a better mental 
picture to many minds, Mr. Hobson’s term would be more read- 
ily understood abroad, and has the added advantage of being 
the English equivalent of Margerie’s structure imbrique. I should 
therefore be glad to see wmbricate structure adopted rather than 


the term which I at first suggested. 
Witiiam H. Hoses. 


GEOLOGICAL SURVEYS IN MISSOURI. 


THE first geological survey of Missouri, having for its field 
of operations the whole state, exclusively, was provided for by 
an act of legislature just fifty-one years ago. A period of par- 
tial surveys by state and national governments had immediately 
preceded this, and a period of exploration and travel, and of 
primitive mining, was of still earlier date. 

The explorations of Joliet, of La Salle, and of Hennepin, in 
the last quarter of the seventeenth century, had transformed the 
Mississippi valley from ¢erra incognita to a promising field for 
adventure or profit, and, with the establishing of a settlement at 
the mouth of the Mississippi by Le Moyne d’Iberville in 1699, 
excursions up the river became frequent. In Le Sueur’s expedi- 
tion, in 1700, the existence of Missourilead ores became known. 
This served, a few years later, as one of the incentives leading to 
the settling of the country by the Company of the West under 
the Crozat patent. From this time to the end of the eighteenth 
century the lead deposits were almost continuously worked, 
sometimes on a large scale, but no record of any careful investi- 
gation has come down to us from these early days. 

With the beginning of the present century and the transfer 
of the territory to the United States, an era of somewhat closer 
observation seems to have been inaugurated. Among the earliest 
papers touching the geology of Missouri is Austin’s ‘“ Descrip- 
tions of the Lead Mines in Upper Louisiana,” written in 1804, 
covering a few pages of the American State Papers.t This ts 
almost entirely descriptive of the lead mines of southeastern 
Missouri, and treats principally of their superficial features and 
conditions of development. During the next thirty years, a 


*Public Lands, Vol. I., p. 188. Reprint Report Mo. Geol. Surv. 1873-74, p. 686. 
207 


208 TALE JOURNAL OFNGEOLOGY: 


number of similar short, descriptive reports appeared in these 
volumes. j 

Between the years 1804 and 1807 the Lewis and Clarke* and 
the Pike 3 expeditions were conducted for the United States gov- 
ernment. These expeditions added much to our knowledge of 
the geography* of the country traversed, but their geological 
results were meagre, and limited to a strip of country adjacent 
to the lines of travel. 

The year 1815 is worthy of noteas marking the beginning of the 
Land Office surveys in the state. These surveys continued until 
1850, and supplied an admirable basis for future areal work in 
geology. Of interest in this connection is the fact that, during 
the first two or three decades of operations, the surveyors were 
required to report to the Land Office, along with their other 
field notes, the presence or absence of mineral on the land 
traversed. Drusy quartz, known as ‘mineral blossom,” and 
other superficial phenomena of wide occurrence, were used as 
criteria, and, as these notes formed the basis for local classifica- 
tion, complaints soon became loud that so much land was being 
‘withdrawn from occupation on account of its being classed as 
‘‘mineral land,” that the settling of the country was seriously 
interfered with. This led eventually to the abandoning of the 
early, crude attempt at accomplishing some of the objects of a 
veological survey. 

Schoolcraft’s well known tours throughout the western coun- 
try were made between the years 1816 and 1819, and the three 
volumes 5 of his observations contain much excellent statistical 


t For specific references see Bull. No. 2, Geol. Surv. of Mo., 1890, Bibliography 
pp. 46 and 48. 

? Travels to the Source of the Missouri River. By Capts. Lewis and Clarke, 1809 
and 1814. 

3 Expeditions to the Sources of the Mississippi, etc. By Maj. Z. M. Pike, 1810 
and 1811. 

4Reference to the geographical results of this and other early explorations and 
surveys will be found in a paper by the writer entitled, “The Mapping of Missouri,” 
Trans. Acad. Science of St. Louis, No. 8, Vol. VI., 1893. 

5 Views of the Lead Mines of Missouri, etc., 1819. 

Journal of a Tour into the Interior of Missouri and Arkansas, etc., 1821. 

Scenes and Adventures in the Semi-Alpine Region of the Ozark Mts., etc., 1853. 


GEOLOGICAL SORVEYVS TN MISSO ORT. 209 


and descriptive matter relating to Missouri, and especially to the 
mines and topography. 

The Long expedition of 1819,’ similar in nature to the Lewis 
and Clarke and the Pike expeditions, was equally poor in geo- 
logical results. 

In the year 1821, Thomas Nuttal, the botanist, recorded cer- 
tain observations on the “ Geological Structure of the Valley of 
the Mississippi’’* in which he alludes to the limestones of the 
valley and correlates them with Martin’s Petrifacta Derbiensis. 
This, as Professor H. S. Williams has already pointed out,3 is 
probably the first recognition of ‘Carboniferous rocks” in the 
region. Soon after this, in 1822, Dr. Edwin James called atten- 
tion to the existence of a sandstone in the Ozark mountains of 
southeastern Missouri, with a clay slate, like the primitive slate of 
New England, intervening between it and the granite. This 
was the first suggestion of the presence of Cambrian or Lower 
Silurian rocks in Missouri. 

During the next ten and more years much attention was 
attracted to Missouriand other Mississippi valley states, through 
the extension of mining operations, especially in lowa and Wis- 
consin. In volume 12 of the American Journal of Sctence, 1827, 
there are a number of references to mines and descriptions of 
minerals found. - 

During the years 1834 and 1835, G. W. Featherstonehaugh 
made his well known trip through Missouri and other western 
states.> In his reports he frequently refers to the limestones 
along the Mississippi as of Carboniferous age, and to the abund- 
ance of fossils in the exposures between St. Louis and Hercu- 
laneum, some of which he has found identical with European 

t Account of an Expedition from Pittsburgh to the Rocky Mts., etc., 1823. 

2Jour. Acad. Sci., Philadelphia, 1821, Vol. 2. 

3 Bull. No. 80, U. S. Geol. Surv., pp. 25 and 137. 

4Jour. Acad. Sci., Philadelphia, 1822, Vol. 2. 

Also: C. D. Waicott, Bull. 81, U. S. Geol. Surv. 

5 Geol. Report of the Elevated Country between the Missouri and Red Rivers, 
1835. 


Reconnaissance to the Green Bay and the Wisconsin Territory, 1836. 


210 IEE I GUINEAVE, (OB (CHE OUL OE 


forms. From this and other statements it is plain that he did 
not discriminate between the different limestone formations 
which we now recognize in the Mississippi valley. He made a 
special examination of southeastern Missouri, and expresses the 
conclusion that the disseminated lead ore of Mine la Motte must 
necessarily have been deposited at the same time as the lime- 
stone ; also that the veins of this country undoubtedly descend 
very deep towards the central part of the earth ; and, finally, 
that the ore in these veins was ‘“‘ projected from below,” the lateral 
veins from a main lode being compared to the branches of 
trap dikes, while the red clay is paralleled by the red mud 
accompanying volcanic eruptions in Sicily. The iron ores of 
Missouri, he also states, are of direct subterranean origin and 
fill veins or fissures produced by dislocation. 

Though such ideas seem extravagant to us now, they were 
discussed and believed by scientific men of the day. Thus, in 
the proceedings of the fifth session of the American Association 
of Geologists and Naturalists, after a statement of Professor J. 
Locke’s, that the Trenton age of the rocks containing lead ores 
of the upper Mississippi had been determined, Dr. Houghton 
replied that he did not think the ores were confined to any spe- 
cial limestone, but that they had been sublimed and segregated 
through the heat of intrusive trap. R. E. Rogers expressed him- 
self in support of a similar explanation. In answer to this Dr. 
H. King sagaciously remarked that no volcanic or igneous 
action had taken place in Missouri or elsewhere in this lead 
region, and thus could not have influenced the segregation of 
the lead ; that the subjacent rocks were not traversed by dikes, 
and that the lead ore was imbedded in the rock, like masses of 
chert... Again Mr. J. T. Hodge, in 1842, in a long article on the 
Missouri and Wisconsin-lowa mining regions, after describing 
copper deposits of Missouri, concludes that the copper ore had 
apparently been projected from below, either melted by sub- 
limation or by slower electrical causes.” 

tSee Am. Jour. Sci., Series I., Vol. 47, 1844, p. 106. 

2Am. Jour. Sci., Series I., Vol. 43, 1842, p. 60. 


GEOLOGICAL SURVEYS IN MISSOURI. 211 


The year 1840 brings us to the date of publication of Owen's 
report on the Mineral Lands of the United States in portions of 
Iowa, Wisconsin and Missouri,’ following closely upon his report 
as state geologist of Indiana upon work of 1838 and 1839. In 
1844, a second and revised edition of his Mineral Lands report 
was issued, and, in 1852, his final report on Wisconsin, Iowa, and 
Minnesota appeared. These reports supplied the guiding lines 
along which later stratigraphic work in the Mississippi valley 
. was done. Without attempting here to present the history of 
this work,” its bearing upon the future work in Missouri calls for 
brief mention. In the Indiana reports Owen makes a separation 
of the rocks, in harmony with the English classification, into: 
(1) Bituminous Coal formation; (2) Mountain limestone , 
(3) Grauwacke ; (4) Crystalline and inferior stratified rocks. 
In the succeeding reports, as the results of wider observation 
and more thorough study, the classification was changed and 
differentiated until, in the final report, we find a classification 
which, not only in its general features, but in many of its 
details, is still adhered to in Missouri. The map accompanying 
this report attempts a representation of the areal geology of the 
northern half of the state. On this map the western margin, as 
far east as Wellington, is colored as belonging to the Upper 
Series of the Carboniferous limestone; along the Mississippi 
river a similar belt of both the Upper and Lower Series is 
represented ; while, along the Missouri river, from above Jeffer- 
son City to Tower Rock, is an area of Lower Magnesian lime- 
stone. Between these a broad stretch of Coal Measures is 
shown. 

The explorations and surveys thus far referred to were the 
results of private enterprise or were made under the auspices of 
the national government. The earliest record we have of action 
on the part of the state is in the message of Governor Lilburn 
W. Boggs in 1833. He there recommends an appropriation for 


= House Exec. Doc., No. 239, 26th Congress, Ist Session. 


2For summary concerning the Devonian and Carboniferous, see H. S. Williams, 
Bull. 80, U. S. Geol. Surv., p. 137 e¢ seq. 


22 RHE JOORNALVOP,GHOLOGY, 


a geological survey as an adjunct to a general system of internal 
improvement. Shortly after this a Board of Internal Improve- 
ments was formed, and, among other works, surveys of the 
Meramec, of the Salt, of the North Grande and of the Osage 
rivers were started. In connection with this, a geological exam- 
ination by Dr. Henry King was made along the Osage river, and 
a report of twenty pages was published in 1840." 

Much of this report is devoted to the topography and soils, 
and to a description of occurrences of ore. Dr. King assigns all 
of the rocks of the region to the Carboniferous formation and 
separates them into two series : (1) A lower Galeniferous or 
lead “series | (2) an) upper Coal series) By the former jhe 
plainly means the magnesian limestones and associated sand- 
stones, though the section given is very imperfect ; in the latter 
he includes the Encrinital or Lower Carboniferous limestones as 
well as the overlying coal beds, sandstones, and shales. The 
change between the two series is so marked, however, that he 
expresses the feeling that an entire separation of the two is 
almost justifiable. The lead ores of the region he assigns to the 
uppermost member of the lower series; the surface float ore, or 
‘patch mineral,’ as he calls it, he determines correctly to be 
residuary from the decay of the limestone. 

After this, further investigations by the state seem to have 
fallen into neglect for several years ; but, by 1846, the subject 
again excited public attention and the question of a geological 
survey called forth a number of memorials from cenventions, and 
of papers prepared by scientific associations, and was further 
recommended in the messages of several governors. Finally, 
by an act approved February 24, 1853, the First geological sur- 
vey of Missouri was authorized.?, The act controlling the First 
geological survey provided for the appointing by the governor 

1 Senate Journal, Appendix, Ist Session, 11th Gen. Assembly, 1840, pp. 506-525. 


? Additional information beyond what is given in the following pages, relating 
especially to the laws governing the various state surveys, their organization, and 
plans of work, wiil be found in an historical sketch of Missouri Geological Surveys, 
forming part of the writer’s Biennial Report to the 36th General Assembly, House 
Journal, 1891. 


GEOLOGICAL SURVEVS IN MISSOURT. ZA 


of a state geologist, who, in turn, was allowed the appointing of 
not more than four assistants, who were to be skilful chemists, 
and of such other subordinate assistants as he might deem nec- 
essary. The work of the survey was to include stratigraphic 
and structural geology and special studies of economic geology. 
Annual reports were required, and a final report, or a complete 
memoir on the geology of the state, was to be prepared on the 
completion of the survey. Specimens in triplicate were to be 
collected and forwarded to the Secretary of State; one set for 
a cabinet in the state capitol, another for the state university, 
and the last for the city of St. Louis. Ten thousand dollars 
annually for a term of two years were appropriated. 

Pursuant to the instructions of this law, Professor G. C. 
Swallow was appointed state geologist by the governor in 1853. 
Professor Swallow came directly from Maine, where he had been 
engaged in teaching. The survey continued in active operation 
until, June 1861, under the direction of Professor Swallow. The 
controlling plan of the work as laid down by him, in the letter 
of transmittal accompanying his second annual report, was to 
prepare: ‘‘ First, an outline of the geology of the state; second, 
a general view of the mineral wealth of the mining districts ; 
third, an exposition of the agricultural and manufacturing 
resources of the state; fourth, reports in detail upon as many 
counties as possible.” 

Five reports were published by this survey, but the second, 
of 447 pages (with which is printed the first, of but four pages) 
is the only one which embodies the results of field work, and 
this is the one generally known as the Swallow report. The 
others are very brief reports of administration and progress. 
Part I of this Second Annual Report contains chapters by Pro- 
fessor Swallow on the general geology of the state and two 
county reports; Part II contains a chapter by Dr. Litton on the 
lead mines of southeastern Missouri, and three county reports 
by Meek and Shumard, as well as several general cross sections 
and a short paper on paleontology. 

After the issue of this report the survey continued in active 


214 THE JOURNAL OF GEOLOGY, 


operation until 1861, during which time its labors seemed to 
have been centered upon systematic county work, leading to 
the production of special county maps and reports. A table 
contained in the fifth report of progress shows that, up to the 
end of 1860, field work had been completed in eighty counties, 
and of these, reports had been made upon thirty-three ; in a 
considerable number of other counties more or less work had 
been done. Five of these reports were contained in the Second 
Annual, and twenty more constitute a report issued in 1873; 
others were probably used in the preparation of the county 
descriptions of the other reports of 1873 to 1874. In addition to 
this work, during the period of the first survey, Professor Swal- 
low made an official report of ninety-three pages on the South- 
west Branch of the Pacific Railway. 

Reviewing, briefly, this work of the First geological survey, 
we must recognize as remarkable and excellent the classification 
of the rocks which are evolved, as well as the general accuracy 
with which the distribution of the formations was defined, espe- 
cially when the short time is considered; avowedly under the 
control of Hall’s New York classification and nomenclature, 
published in 1843, though undoubtedly assisted, yet not misled 
by Owen’s results, Swallow and his assistants established a table 
of formations, and outlined a geographical map of the state 
which remains to this day unchanged in its larger features. 

From 1860 to 1870, geological work was nearly at a stand- 
still in the state. During this period, however, Professor Swallow, 
as professor of geology at the state university, and various of 
his assistants in different capacities, extended their observations 
in the state, and published the results in scientific journals or in 
the proceedings of scientific societies.’ 

In March, 1870, an act was passed authorizing the Second 
geological survey. The provisions of this act were in the main 
similar to those of the’first, with the exception that the Bureau 
was placed under the control of a board of managers of nine 


‘For a Bibliography of the Geology of Missouri, see Bull. No. 2, Mo. Geol. Survey, 
1890. 


GEOLOGICAL SURVEYS IN MISSOURI. 215 


members. The state geologist was allowed to appoint one 
assistant state geologist, who was required to be a chemist, at an 
annual salary of $2,000; also other subordinate assistants at not 
more than $1.50 per day. Provision for the appointment by 
the Board of a state assayer was also made. For the “ general 
expenses’ of the bureau the sum of $7,500 was allowed annually 
Under this law Albert D. Hager, previously of the Vermont 
survey, was appointed state geologist. The law was amended 
in March, 1871. The number of the members of the Board was 
reduced to four, and the allowance for the annual expenses raised 
to $10,000. Mr. Hager held this position until August, 1871, 
and published one report of progress, twenty-one pages in 
length, in which he briefly notices the chief building stones and 
minerals of the state. After Mr. Hager’s resignation, Dr. J. C. 
Norwood was in temporary charge. In November, 1871, Mr. 
Raphael Pumpelly was appointed state geologist. He resigned 
from the position in May, 1873. 

Up to the time of Mr. Pumpelly’s appointment, very little 
had been made public of the results of the surveys, and the 
changes of management must necessarily have retarded and 
weakened the work. Notwithstanding this, however, Gover- 
nor B. Gratz Brown, in his message of December, 1871, com- 
mends the survey warmly to the Legislature, and, as a result, the 
law was amended in the following March, and the sum of $20,000 
was appropriated annually for the salaries and expenses of the 


b) 


Bureau. 

Two classes of work were provided for in the Pumpelly sur- 
vey, 2. ¢., (1) the study of the stratigraphy of the state; (2) the 
study of the mineral deposits. The stratigraphic work was 
divided into five departments covering different sections of the 
state; that of economic geology was divided into three, includ- 
ing a department of iron ores and metallurgy, a department of 
ores other than iron, and a department of fuels and materials of 
construction other than iron and wood. Under the Pumpelly 
management two reports were issued in 1873. The first was an 
octavo of 323 pages, already referred to as containing twenty 


216 THE JOURNAL OF GEOLOGY. 


county reports, prepared during the Swallow survey." The sec- 
ond volume was a large octavo of 655 pages? transmitted in 
Novell; 1373, — leaves JI consists, first, of a chapter on the geology 
of Pilot Knob and vicinity by Mr. Pumpelly; the second chap- 
ter embodies analyses of ores, fuels and pig irons; chapters II 
to IV, inclusive, constitute a partial report on the iron ores of 
Missouri by Dr. Adolph Schmidt. Part II consists of fifteen chap- 
ters and three appendices; of these, chapters I to VI contain 
general information relating to the coal fields of the state by 
Prof. G. C. Broadhead; chapters VII to VIII are on the geol- 
ogy of Lincoln county by Prof. W. B. Potter; chapters IX to 
XV consist of reports on seven counties by G. C. Broadhead ; 
appendices A, B and C relate to building stones and contain a 
list of Coal Measure fossils. 

After Mr. Pumpelly’s resignation, Prof. G. C. Broadhead was 
appointed state geologist and assumed charge in July, 1873. 
During this administration the examinations of the iron ores 
and of the lead and zinc deposits were continued, and sur- 
veys for a number of county reports were made. One volume 
was issued by the Broadhead survey.3 This is a large octavo of 
over 790 pages transmitted in August, 1874. Chapters I to VI, 
inclusive, are upon general topics relating to the history of 
exploration and the general geology of the state by Professor 
Broadhead; chapters VI to XXI, inclusive, consist of reports 
on fifteen counties; chapters XXII to XXXII, inclusive, and 
XXXIV, describe the lead and zinc deposits of the state from 
work done by Dr. Schmidt and Mr. A. Leonhard; chapters 
XXXIII and XXXV relate to the iron ores of southeastern 


«Reports on the Geological Survey of the State of Missouri, 1855-1871, by G. C« 
Broadhead, F. B. Meek and B. F. Shumard, Jefferson City, 1873, pp. 324 and iv. 


2Geological Survey of Missouri, Raphael Pumpelly, Director. Preliminary 
Report on the Iron Ores and Coal Fields, from the field work of 1872, with 190 
illustrations in the text and an atlas. New York: Julius Bien, 1873. P. xvi., 214 
and 441. 


3 Report of the Geological Survey of Missouri, including field work of 1873-74, 
with 91 illustrations and an atlas. Garland C. Broadhead, State Geologist, Jefferson 


City, 1874. . Pp. 734, L. 4, 50. 


GEOLOGICAL SURVEYS IN MISSOURI. 27 


Missouri. Appendices A, B, C and D contain much statistical 
and other matter of subordinate interest. 

The survey was discontinued after the year 1874, and most 
of its working material was transferred to the state School of 
Mines at Rolla, of which the president, Dr. Charles P. Williams, 
was made acting state geologist, with a nominal appropriation. 
Little field work seems to have been carried on under Dr. 
Williams, and, after the year 1876, no further .support was 
extended to the work by the state. One report was prepared 
by Dr. Williams, which consists of a small octavo of 117 pages. 
It contains a chapter on the ‘‘ Mineralogy and General Metal- 
lurgy of Lead,” one on the “Zinc Industry of Missouri,” one 
on the ‘Iron Industry,” and one on “Shannon County”’; in the 
appendices are given a few statistics of lead and zinc, and a 
‘““Note on the Occurrence of Gold in Northwestern Missouri.”’ 

Reviewing the results of the Second geological survey, its 
contribution to our knowledge of the geology of the state con- 
sisted principally : (1) of Pumpelly’s observations, too soon inter- 
rupted, upon the crystalline rocks, whose work threw much new 
light upon their nature and relations, though the report has left 
us in some doubt as to whether he considered the whole mass 
of the porphyries metamorphosed clastics, or whether he meant 
this to apply only to the Pilot Knob beds ; (2) of Broadhead’s 
detailed stratigraphic results in the Coal Measures which placed 
on record many new and valuable sections, added much con- 
cerning their correlation, and demonstrated the thickness of this 
formation to be much greater than had been formerly believed ; 
(3) of Schmidt’s report on the iron ores and lead and zinc 
deposits, especially strong in its treatment of the mineralogy, 
but deficient in its interpretations of structure, and lacking in 
suggestions as to origin and processes. The classification of 
the clastic rocks remained substantially the same as tabulated 
by Swallow and Shumard, the principal changes displayed in the 
chart opposite page 18 of the report of 1873-74 being in the 
subdivisions of the Lower Carboniferous; in the transference of the 
Chouteau, Vermicular and Lithographic stages to this series ; and 


218 THE JOURNAL OF GEOLOGY: 


in the assignment of the Third Magnesian limestone and all 
below it to the Potsdam period. 

Summarizing the products of both the First and Second 
surveys, we find that there were published six volumes, varying 
in length from ninety-three to over 700 pages, and four pam- 
phlets, aggregating about fifty pages. The appropriations for 
these two geological surveys, as given by Broadhead.* are as 


follows: 
APPROPRIATIONS. EXPENDITURES FOR 
PRINTING. | 
From 1853 to 1862 - - - $105,000 $5,000 
1870 and 1871 - - - 12,500 
Under acts of 1872, 1873 and 1874 60,000 19,320 
In 1876 and 1877, and by School of 
Mines 2 a ata 2 5,000 1,500 
Printing, 1873 - - - - 12,000 
Printing, 1876 - - - 1,500 
Total 2 = - - ¢196,000 $25,820 
Unexpended appropriations - 19,814? 
Total expended - - $176,185 
Balance for salaries and current ex- 
penses : - - - 150,365 


After the stoppage of the apology for a geological survey, 
for which provision was made under Professor Williams’ con- 
trol, no public geological work was conducted until the year 
1884, when topographic work was begun in the state by the 
United States geological survey. This was continued, until 
July, 1889, up to which time about one-third of the state was 
mapped on sheets of a scale of two miles to the inch, and with 
In addition Mr. W J McGee 


was detailed in 1887, by the national survey, to make a brief 


contour intervals of fifty feet. 


study of the geology of a portion of Macon county, the results of 


tMissouri Geological Surveys. Historical Memoir. Trans. Acad. Sci. of St. 
Louis. Vol. 1V. Pp. 611-614. 

2 We are informed by Professor Broadhead that the larger part of this unexpended 
appropriation belonged to the period of the Swallow Survey, though part of it also 
reverted during the Hager administration of 1870 to 1871. 


GEOLOGICAL SURVEYS IN MISSOURI. 219 


which are published in Vol. V. of the Transactions of the St. Louis 
Academy of Science. 

In May, 1889, the act authorizing the present, or Third 
geological survey, was approved. It was evidently framed 
upon the laws of the preceding surveys, though it differed from 
them in detail. The most noticeable differences are the absence 
of a requirement to collect specimens in triplicate, and the 
absence of a clause requiring county maps and reports to be 
prepared. The state geologist is, however, directed to have 
complete and detailed maps and reports of counties or districts 
prepared. The appropriation for the two years, 1889 and 1890, 
was $20,000; that for 1891 and 1892 was $40,000; out of this 
all salaries and expenses were to be paid, including cost of pub- 
lication. For the years 1893 and 1894, $20,000 have been appro- 
priated, though the paper for publications is furnished in addi- 
tion. 

The writer was elected state geologist in August, 1889, and 
entered upon the discharge of his duties the end of September 
following. The plan of work adopted for this survey was: (a) 
to prepare a series of monographic reports upon separate sub- 
jects, which may be called Subject reports, applying to the 
whole state; those subjects of direct economic importance to 
receive first consideration; (2) to prepare successively a series 
of detailed maps of different portions of the state, and to 
accompany these with special reports containing much descrip- 
tive detail, which we may call Area or Sheet reports. 

The subjects of work so far undertaken have been: the 
lead and zinc deposits; the coals and the Coal Measures; the 
clays; the iron ores, the mineral waters; the building stones ; 
the crystalline rocks; the Quaternary, or, more exactly, the 
glacial geology ; the paleontology ; the hypsometry ; general 
geologic mapping. Work has advanced on all of these subjects 
to varying extents. The study of the lead and zinc deposits 
was begun in codperation with the national geological survey, 
but has been carried to completion by the state survey, and the 
report is now nearly finished. A Preliminary Report of 226 


220 TLS JO OTLINAE VOR MG TAOM OG NA 


pages on the Coals of the state, by the writer, has been issued, 
but a great bulk of additional information has been gathered for 
a final report. The field work for the report on Clays was 
finished last year, and the report, by Prof. H. A. Wheeler, is 
now well advanced. A report on the Iron Ores of 391 pages, 
by Frank L. Nason, was published in 1892, together with one of 
280 pages on the Mineral Waters, by Paul Schweitzer. The 
building stones were studied first by G. E. Ladd and later by 
Hiram Philips, but the field work is not yet completed, and had 
to be suspended this year. The crystalline rocks were studied 
by Erasmus Haworth and the report is written, but is withheld 
from publication for lack of funds. Field work for a prelimi- 
nary report on the glacial geology, by J. E. Todd, was com- 
pleted last year, and the report will soon be ready for transmis- 
sion. An exhaustive review of the paleontology of the state by 
Charles R. Keyes is ready for publication. All available data 
relating to the hypsometry of the state have been collected and 
tabulated, and a few months additional work will put them in 
shape for publication. Along with the prosecution of work on 
these general subjects, many additional facts for more exact and 
detailed geological mapping have been collected; but in addi- 
tion to this, mapping of the formations has been specially done 
over certain important areas of the southwestern and northeast- 
ern portions of the state. 

For the Area or Sheet reports, fifteen sheets have been pre- 
pared, distributed over the central portion of the state along the 
margin of the Coal Measures, over the southwestern lead and 
zinc district, and over the southeastern lead district and Archean 
area. These sheets are on a scale of one mile to the inch with 
a twenty-foot contour interval, and cover each a quadrilateral 
of fifteen minutes of latitude and longitude. They include, in 
addition to the topography and general geology, much detail of 
special economic importance. Three of these sheets have been 
engraved, and the accompanying reports printed. The others 
are about ready for the engraver, and the reports are partly 
prepared. 


GEOLOGICAL SURVEYS [IN MISSOURI. 221 


Summarizing the official publications of the Third survey to 
date they are as follows: 
Reports published: 

Vol. I. A Preliminary Report on Coal, 8vo, 226 pages; 
Vol. Il. Report on Iron Ores, 8vo, 391 pages; Wolk, ILE. 
Report on Mineral Waters, 8vo; 280 pages; Five Bulletins, 
including a Bibliography of the Geology of Missouri, and arti- 
cles on the coals, building stones and clays, mineral waters, 
crystalline rocks, and paleontology, aggregating 470 octavo 
pages. Also two administrative Biennial Reports aggregating 
gO pages. 

Three sheets and accompanying reports as follows: No. I. 
Higginsville Sheet and large folio report, 18 pages; No. II. 
Bevier Sheet and octavo report, 90 pages; No. III. Iron 
Mountain Sheet and octavo report, 96 pages. 

Reports completed but not published: 

Report on Paleontology, 400 8vo pages (estimated); Report 
on the Crystalline Rocks, 300 pages (estimated). 
Reports nearly completed: 

Report on Lead and Zinc Deposits, 500 8vo pages (esti- 
mated); Report on Clays, 400 8vo pages (estimated); Report 
on Quaternary Geology, 150 8vo pages (estimated); Report on 
Hypsometry, 150 8vo pages (estimated). 

Reports only partly prepared: 

Final Report on the Coal Measures; reports on twelve 
sheets of detailed mapping. . 

ARTHUR WINSLOW. 


JE ION TIF OLR AILS. 


THE doctrine of isostasy has been tentatively accepted by many 
working geologists. It finds application in various departments 
of geology, but nowhere more conspicuously than in glaciology. 
Without passing judgment on the doctrine, and without attempt- 
ing to restrict the field of its application, attention is called to 
a misapprehension to which it has given rise. This misappre- 
hension is widespread in the popular mind, and has even found 
_a foothold among those who have given attention to glacial 
geology. 

Among the hypotheses which have gained more or less cur- 
rency in explanation of the Pleistocene glacial climate, is that of 
northward elevation. Whatever may be thought of this hypoth- 
esis from @ priori considerations, or whatever may be thought of 
the evidence which is adduced in support of it, it has come to 
have an appendix which we believe to be false. This appendix 
seems not to have accompanied the hypothesis at the outset, and 
some of the advocates of the hypothesis do not appear to have 
given their sanction to the appendix, though their names are 
sometimes connected with it. 

The hypothesis is, that northward elevation lowered the tem- 
perature of the region affected to such an extent as to occasion the 
accumulation of the Pleistocene ice-sheet. The appendix is, that 
the elevated area sank under the weight of ice for which it was 
responsible, until, as a result of the sinking thus effected, the cli- 
mate was so far ameliorated as to bring about the melting of the 
ice-sheet and the end of the glacial period. The appendix is 
sometimes stated in milder form, the depression resulting from 
the weight of the ice being looked upon as only one of the 
causes which brought about the dissolution of the ice-sheet. 


This view, both in its wider and in its more restricted sense, we 
222 


BP DITIORTALES: 223 


believe to be without foundation. Its fallacy appears when the 
quantitative elements of the problem are considered. 

Let it be assumed that northward elevation was the cause of — 
the cold climate which made the development of the Pleistocene 
ice-sheet possible. Let it be assumed further (and this is the 
assumption most favorable to the doctrine here opposed), that 
the elevated region was in isostatic equilibrium at the time the 
ice began to accumulate. Let it be assumed also, that the 
average specific gravity of the mass of snow and ice of the 
ice-sheet was one-third that of the rocks of the earth’s crust. 
On the doctrine of isostasy, depression should have accompa- 
nied the accumulation of snow and ice. When the central part 
of the snow-field had a depth of 300 feet, the maximum depres- 
sion which it could have caused, under the assumed conditions, 
was 100 feet. At the minimum, therefore, the surface of the 
central part of the ice-field must have been 200 feet higher than 
the surface of the land before the ice-field formed. Nearer the 
margins of the ice-field, where the ice was thinner, both the 
depression of the land surface and the accompanying elevation 
of the snow surface would have been less; but each point of the 
surface of the snow-field must have been higher than the corre- 
sponding point of the surface of the land at the time the ice 
began to accumulate, and the temperature at all points must 
have been correspondingly reduced. Instead of being amelio- 
rated by the depression of the land surface, the very conditions 
which brought about this depression were causing the climate to 
become progressively more severe. When the ice had attained 
a thickness of 3,000 feet, it might have occasioned a maximum 
depression of the subjacent land surface to the extent of 1,000 
feet, and therefore a minimum elevation of the ice surface at the 
same point, to the extent of 2,000 feet. While, as before, both 
the depression of the subjacent land surface and the correlative 
elevation of the surface of the ice-sheet would have been less near 
the margins of the snow-field than at its center, it still remains 
true that each point of the entire surface of the ice must have been 
higher than the corresponding point of the surface of the land at 


224 ULE J OOLINAL TOL NGLAOLO GN 


the time the ice began to accumulate, and higher than the corre- 
sponding point of the surface of the ice at every earlier stage. 
When 3,000 feet of ice had accumulated, and when this body of 
ice had caused its full measure of depression, the temperature 
over it must have been reduced at each point by an amount cor- 
responding to the actual increase of elevation of the snow surface | 
over the pre-existent land surface at that point. The force of 
the point here made is in no way lessened if the depression 
caused by the accumulation of the ice lags behind the accumula- 
tion itself. In so far as the sinking lags behind the loading, the 
temperature of the surface is reduced beyond the limits indicated. 
The principles here referred to will neither be reversed in their 
operation, nor rendered nugatory, by further accumulation of ice. 
So long as the ice thickens, it will remain true at all times that 
each point of the surface of the ice-field must be higher than the 
corresponding point at any earlier stage in the process of accumu- 
lation, isostasy alone being considered. The elevation of the ice 
surface (and this is the surface which determines the climate), 
will overbalance any depression of the land surface which the ice 
can cause by the disturbance of isostatic equilibrium. There 
is, therefore, not only no tendency to the amelioration of climate 
as the result of excessive snow accumulation, but there is a con- 
stant reduction of temperature. Whatever may have caused the 
dissolution of the Pleistocene ice-sheet, it was not the ameliora- 
tion of climate resulting from the depression caused by the weight 
of the ice itself, under conditions of isostasy. IRS IDSs 
Wir this number, THE JOURNAL OF GEOLOGy begins the pub- 

lication of a series of articles on the geological surveys of the 
various states of the Union. These articles will be prepared, so 
far as practicable, by the official geologists of the several states. 
Their purpose is to publish to the geological world the present 
condition of geological work in the various regions with which 
| they deal. They will indicate what has been done, and by 
whom. They will make known the various plans on which sur- 
vey work has been prosecuted in the several states. They will 


EDITORIALS. 225 


state the problems which still remain to be solved, and some- 
thing of their relative importance. They will bring out the sci- 
entific and economic advantages which have resulted, directly 
or indirectly, from the surveys already executed. They will 
indicate the general scope of the more important publications, 
both cartographic and textual, which have appeared, and while 
they are not intended to be bibliographic primarily, they will 
contain references to the more important publications and 
to such bibliographies as may have been compiled. In some 
cases, at least, they will give the cost of the work which 
has been accomplished. The plan also involves a series of 
articles on the surveys in foreign countries. It is hoped and 
believed that these papers will be of much value. A consider- 
able period of time will necessarily elapse before the series is 
completed, but in the end it is believed that it will constitute a 
valuable compendium of geological work throughout the world. 


Rae DES: 


REVIEWS. 


The Economic Geology of the United States. By R. S. Tarr, 
Assistant Professor of Geology at Cornell University. 8vo, 
509 pp. Macmillan & Co., 1894. 


Tus volume discusses the ore deposits and other minerals and 
rocks of commercial value found in the United States, as well as a few 
of the foreign deposits of a similar nature. The book is divided into 
three parts. Part I. treats of the general mineralogical, geological 
and technical subjects more or less directly related to the various 
‘mining industries. It gives, first, a chapter on ““Common Rock and 
Vein-Forming Minerals,” followed by chapters on the ‘Rocks of the 
Earth’s Crust,” the ‘‘ Physical Geography and Geology of the United 
States,” the “Origin of Ore Deposits,’ and ‘‘Mining Terms and 
Methods.” Part Il. treats of “ Metalliferous Deposits,” including 
the ores and deposits of the useful metals. Part III. treats of the 
““Non-metallic Mineral Products,” such as coal, petroleum, fertilizers, 
building stones, etc. In addition, the volume also contains a short 
appendix on the ‘Literature of Economic Geology.” The object of 
this volume, as stated by the author in the preface, is to supply the 
pressing need of a text-book to accompany a series of lectures given by 
him to a class of students in economic geology at Cornell University. 

The book is beautifully printed and neatly bound. The illustra- 
tions are well reproduced, and, in fact, all of the publishers’ work on 
the book is very good and reflects credit on Macmillan & Co. The 
book is written in good language, and the general scheme in the 
arrangement of the subject matter is logical, but the text is deficient 
and contains many erroneous statements. The chapters on the “ Rocks 
of the Earth’s Crust” and on the “ Physical Geography and Geology of 
the United States,” give a fair general idea of those subjects, although 
even here there are a number of inaccuracies. The chapter on 
“Common Rock and Vein-Forming Minerals” and parts II. and III. 
of the book, treating of “ Metalliferous Deposits” and “‘ Non-Metallic 
Mineral Products,” however, relate more especially to economic geol- 

226 


REVIEWS. 22y, 


ogy,and are the essential features of the volume. They, therefore, 
deserve consideration in some detail. 

The most important feature of a book of this kind is the discussion of 
ore deposits, yet at the outset a faulty definition of the term “ore” is 
given. The author says, on page 15, ‘‘an ore may be defined as a mineral 
with a metallic base.” Unless further qualified, this definition is, to 
say the least, vague, for though all ores have metallic bases, there are 
a number of important minerals with metallic bases which are not 
ores. Thus, oxide of iron, sulphide of lead, sulphide of copper and 
other materials have metallic bases, and under proper conditions are 
ores; but gypsum, calcite, baryta, mica, and many other minerals have 
metallic bases and are not ores. Moreover, though many ores are 
minerals, many others are not minerals at all, but are common rocks 
having some special metallic constituent as their only unusual feature. 
Thus the ore of the Calumet and Hecla copper mines is a cupriferous 
conglomerate, the Mansfeld copper deposits of Germany are cuprif- 
erous shales, and many other similar instances might be mentioned. 
The author adds that, “properly speaking, the metallic constituent 
should be a predominant constituent.” Though in some ores the 
metallic constituent is a predominant one, yet in some of the most 
important ores the metal forms only a small, and often an insignificant, 
constitutent. In most gold ores the metallic constituent forms but a 
fraction of one per cent. of the ore, and in most silver ores the silver 
forms but a slightly larger amount. In copper deposits, the copper 
rarely forms a large percentage of the ore, and in many other cases 
the metallic constituent is entirely subordinate. 

The author states that ‘“‘the miner considers an ore to be a mineral 
with a metallic base, occurring in sufficient abundance to be economi- 
cally valuable; but from the scientific standpoint, a grain of magnetite 
in a granite rock is as much an ore as a bed of this mineral.’’ The 
term ore is essentially a technical mining term, and has no scientific 
significance whatever. When a metal can be profitably extracted from 
a certain material, that material becomes an ore ; but other materials may 
contain just as much of the same metal, and yet, on account of their 
mineralogical or other features, they may not be commercially profitable 
sources of the metal, and then they are not ores. Whether a material 
is an ore or not, is dependent on commercial conditions, which may 
vary from time to time; and this very fact prevents the term from 
having a scientific meaning. 


228 THE JOURNAL OF *GELOLOGY. 


On page 16 the author says that “the group of silicates is 
extremely large, including many of the important rock-forming mine- 
rals, but as ores they are of little importance.” He has evidently 
overlooked the fact that calamine, a hydrous silicate of zinc, is an 
important ore, and that garnierite, a hydrous silicate of nickel and mag- 
nesia, is the source of a large part of the nickel of commerce. ‘The latter 
is the ore mined at New Caledonia, off the coast of Australia, one of the 
two largest nickel producing regions in the world. It also occurs in 
the United States. The author again overlooks this silicate when, on 
page 26, in enumerating the ores of nickel, he says, ‘‘nickel is obtainen 
from the two sulphides, millerite, niccoliferous pyrrhotite, and the arse- 
nide niccolite.” In other deposits also silicates form a minor but an 
important part of the ore, as in the case of chrysocolla in the copper 
ores of Arizona. 

- On page 18 the author states that, ““Sometimes, though not com- 
-monly, gold occurs in iron pyrites in invisible grains.” It is almost 
unnecessary to say that one of the most common modes of occurrence 
of gold is in intimate association with iron pyrites, so that this state- 
ment is extremely misleading. 

On page 20 the author says: ‘‘Gold occurs in the earth in only 
two mineralogical forms, so far as known, one in association with tel- 
lurium, the other native, the latter being its typical occurrence and the 
one from which the gold in use is obtained.” It is true that native 
gold is the source of most of the gold in use, but the telluride ores, far 
from producing no commercial gold, are in many mines an important 
source of that metal. At Cripple Creek, in Colorado, the tellurides 
form an important part of many of the ores, and this district produced 
between $2,500,000 and $3,000,000 in gold in 1893. In Boulder county, 
Colorado, tellurides are also of importance, and have been so for many 
years past, while tellurides frequently occur in still other places. 

On page 22 the author, in speaking of copper, says: “Its most 
common occurrence, however, is as the sulphide, cha/copyrite (CuF eS,), 
or copper pyrites, which is in reality a sulphide of iron and coppes 
combined, the proportion varying from an exceedingly cupriferous 
variety (chalcopyrite) to pure iron pyrites.” The sulphide of copper 
known as copper pyrites is a definite chemical compound, with pro- 
portions of iron and copper in a definitely fixed ratio, so that the 
mineral cannot vary from an exceedingly cupriferous variety to pure 
iron pyrites. [he same may also be said of other sulphides of copper. 


REVIEWS. 229 


Copper pyrites is often, and even usually, when found in nature, 
mechanically mixed with iron pyrites, and the relative amounts of cop- 
per pyrites and iron pyrites in a deposit may vary considerably. Dif- 
ferent analyses of this mixture of the two minerals may, therefore, 
show varying proportions of copper and iron, but the composition of 
the copper pyrites itself is constant. 

On page 23 the author speaks of the “pale yellow rust” of lead 
ores, and by ‘‘rust”” he means doubtless the carbonate of lead formed 
by the action of surface agencies on the superficial parts of certain 
lead deposits. This product is often stained yellow or brown by the 
oxidation of iron pyrites, which is frequently associated with galena, 
the common ore of lead; but the normal color of the “rust,” or 
carbonate of lead, is white. An oxide of lead of a yellow color may. 
be formed when certain lead minerals are highly heated under suitable 
conditions, but this process would obviously be a very unusual one in 
nature, and the common product of the superficial alteration of galena 
ores is first the sulphate and then the carbonate of lead. 

On page 132 the author, in speaking of iron ores, says: ‘The 
carbonate, siderite, may be considered to be a combination of iron and 
calcite in which the percentage of iron varies even to the point of 
complete replacement of the calcium.” Siderite is a definite chemical 
compound containing iron protoxide and carbonic dioxide in fixed pro- 
portions, while calcite is also a definite chemical compound containing 
calcium oxide and carbonic dioxide in fixed proportions. Both siderite 
and calcite are isomorphous carbonates, and the two crystallize together 
in various proportions. The carbonate of iron, however, can in no 
way be called a ‘‘combination of iron and calcite.” 

The Lake Superior copper and iron districts, which, taken together, 
form one of the most important mining regions in the world, are dis- 
cussed very briefly, but even the descriptions given are inaccu- 
rate. On page 210, in speaking of the Lake Superior copper ores, 
the author says that “in some of the mines, mineralized ores of copper 
are the source of the metal, but the most common ore is native copper 
frequently associated with native silver.’ The fact is that none of the 
copper produced in the Lake Superior region is derived from ‘ mineral- 
ized” * ores of copper, but all of it is obtained from native copper. 
The native copper is sometimes slightly stained green by the forma- 


*By “mineralized ores” it is supposed that the author means the ores in which 
the copper is combined with other elements, forming sulphides, carbonates, oxides, etc. 


230 THE JOURNAL OF CGCHOLOGY. 


tion of a thin crust of carbonate of copper on its surface, but even this 
does not always happen, and one of the remarkable features of the 
Lake Superior region is the very extensive occurrence of copper in its 
native state. Copper sulphides are disseminated through the region, 
and are probably the source from which the native copper was derived 
in nature; but they have not been found to be themselves concentrated 
in commercially important quantities, and are therefore not mined. 
Small quantities of oxide of copper also occur, but are likewise not of 
present importance. 

On page 125 Professor Tarr, in describing a section by Van Hise, 
showing the mode of occurrence and formation of the iron deposits 
in the Penokee-Gogebic range in the Lake Superior region, states that 
Irving and Van Hise have shown that the hematite deposits of that 
region were formed by a replacement of ‘‘ beds of dolomitic limestone.” 
It may be said here that the iron deposits of the Penokee-Gogebic 
"range occur in the Upper Huronian series, which, in this district, con- 
tains no dolomitic limestones. A dolomitic limestone occurs near the 
base of the Lower Huronian of the district, but it has no connection 
whatsoever with the Penokee-Gogebic iron deposits. Van Hise clearly 
states, in his various publications on this subject, that the iron deposits 
of the Penokee-Gogebic range represent a replacement of a siliceous 
rock containing carbonate of iron and other carbonates, and desig- 
nated by him as cherty iron carbonate. One of the principal points 
which Van Hise brings out in the discussion of his theory for the for- 
mation of these deposits is that the change has been largely an oxida- 
tion of the iron carbonate and a replacement of silica by oxide of 
iron. Professor Tarr also gives a geological section illustrating the 
occurrence of the Penokee-Gogebic ores, and designated by him as 
*‘modified from Irving and Van Hise.” In the legend below the sec- 
tion, the iron deposits are referred to as “iron ore, replacing ferru- 
ginous chert’’—a statement not at all in accord with Professor Tarr’s 
text just cited. It is, moreover, difficult to understand on what basis 
an author, who has never studied a region, has “modified” the geo- 
logical sections of other authors who have spent years in investigating 
that region. 

The errors in this book that have already been pointed out are only 
a few among the many that might be mentioned, but they serve to 
show the want of familiarity with the subject and the inaccuracies 
prevalent throughout the volume. 


REVIEWS. 231 


In a work of this kind, brief and concise statements are necessary 
in order to confine the volume to its proper size, but the different 
subjects should receive discussion more or less briefly according to 
their importance, and the more important subjects should not be 
neglected while the less important are treated in detail. The latter 
course not only prevents a book from containing as much useful infor- 
mation as it might otherwise do, but it also makes it extremely mis- 
leading to the student, for it gives him an erroneous idea of the rela- 
“tive importance of the different branches of the subject. Thus, in the 
present volume, the discussion of iron covers 27 pages. Of this num- 
ber only 18 pages are given to the description of iron deposits proper, 
while nine pages are given to the enumeration of statistics which might 
have been condensed into a third of that space. Moreover, the great 
iron region of the Lake Superior country, which supphes more than 
two-thirds of the iron ore used in the United States, receives only 
three pages of treatment. The copper region of the Lake Superior 
country receives only four pages, and the copper and silver region of 
Butte City, Montana, one of the most celebrated mining localities in 
the world, receives only two pages; while other much less important 
subjects receive many pages. Such inequalities might be justifiable 
if the geology of certain regions were so simple that it could be 
described in a few words, even though the commercial features might 
be of great importance. In the instances cited, however, this is not 
the case. 

Economic geology, including both the subject of ore deposits and 
other subjects which properly belong to this branch of geology, is in 
much need of accurate geological work and careful discussion. This 
is especially true in the United States, which is preéminently the 
mining region of the world; and it is unfortunate that a treatise 
relating mostly to the ore deposits of this country should have failed 
to give the subject thorough treatment. The volume, though in some 
parts it need not be severely criticised, shows in most parts an ex- 
tremely superficial knowledge of economic geology, and contains many 
the errors in statements regarding the mineralogical nature of ores and 
geological nature of ore deposits ; it shows a want of knowledge of the 
commercial features of the various mining industries, and it bears evi- 
dence of a lack of the sense of proportion in the amount of space 
given to different subjects. 

R. A. F. PENROSE, JR. 


DAD 
“3+ 


THE JOURNAL OF GEOLOGY. 


The Canadian Ice Age. 
Canada, with Especial Reference to the Life of the Period 
and its Climatal Conditions. By Sir J. Witit1am Dawson, 
GOVEGe Ie Dy ER Seek Gs ete. sMontreally Walliams 
Dawson, 1893. 301 pp., 8vo. 

The work opens with a chapter of historical notices, embracing a 
sketch of the tenets held by the author during the long period of his 

Among these are the following : 


Notes on the Pleistocene Geology of 


studies on Pleistocene phenomena. 
1. The phenomena are not to be explained by any one cause, or by 
any one all-embracing hypothesis. 2. The astronomical changes that 
have been invoked are incapable of fully explaining the facts. 3. 
There has not been, at any time, a polar ice cap. 4. The phenomena 
indicate local mountain glaciers codperating with floating ice in various 
forms. 5. Thecold climate was mainly the result of peculiar geograph- 
ical conditions and of a different distribution of oceanic currents. 6. 
The author quotes freely 
from his previous writings in elucidation of these views, and cites cer- 
tain recent tendencies that seem to him to indicate a drift of opinion 


The close of the period was not very remote. 


towards the views he has held so long. 
In the second chapter he gives the succession of Pleistocene depos- 


its in Canada, as he correlates them, as follows: 


Montreal and Lower St. 
Lawrence. 


J. Wm. Dawson. 
1. 
Surface soil, post-glacial 
alluvia, and peat. 
ia 


boulders, 
and 


Surface Sax1- 


cava sand gravel. 


Boulders in and below sand. 


Ill. 

Upper Leda clay, marine 
shells and drift plants. 
Lower Leda clay, marine 
shells and drift plants. 


IV. 

Lower boulder clay or till. 
Many native and some trav- 
eled boulders. 
ine shells of arctic svecies. 


A few mar- 


North Shore of Lake 
Ontario. 


J. G. Hinde. 


Me : 
Surface soil, stratified sand 
and gravel. 


Il. 
Boulders, sand, etc. Lam- 
inated clay. Upper boulder 
deposit. 


Il. 
Stratified sand and clay, 
with fresh-water shells and 
plants. 


IV. 
Lower boulder clay or till. 
Native and traveled bould- 
ers. 


Belly River, Northwest 
Territory. 
G. M. Dawson. 
It, 


Surface soil and prairie 
alluvium. 


Il. 
Upper boulder clay. 


JOO 
Gray sand with iron-stone 
nodules. Brownish sandy 


clay. Carbonaceous layers 


and peat. Gray sand iron- 
stone. 
IV. 
Lower boulder clay. 


Many traveled boulders. 


REVIEWS. 228 

This is followed by a general view of the entire series of deposits 
of eastern Canada and a discussion of these, in the course of which he 
states the views of the origin of the deposits which are set forth more 
fully in a subsequent part of the book. In the course of the chapter 
he presents a scheme of correlation of the phenomena of the glacial 
period in the Cordilleran region conjointly with those of the region of 
the great plains (in ascending order), in which epeirogenic movements 


constitute the leading feature. 


Cordilleran Region. 


Cordilleran zone at a high elevation, 
severe glaciation; maximum develop- 


ment of Cordilleran glacier. 


Gradual subsidence of Cordilleran re- 
gion; boulder clay of interior plateau and 
Yukon basin ; lower boulder clay of coast 
region; interglacial silty beds at later stage. 


of Cordilieran 
maximum of second glaciation. 


Re-elevation region ; 


Partial subsidence Cordilleran region ; 
formation of white silts; upper boulder 
clay of coast region, probably. 


Cordilleran 
region; general amelioration, closing gla- 


Renewed elevation of 


The following is an abbreviation : 


Region of the Great Piains. 
Correlative subsidence and submergence 
of the great plains with possible contem- 
poraneous elevation of Laurentian axis 
and maximum development of the ice 


_upon it. 


Correlative elevation of western part of 
great plains, probably irregular; forma- 
tion of extensive lakes; interglacial de- 
posits, including peat beds. 


Correlative subsidence of plains; sub- 
mergence to base of Rocky Mountains; 
formation second boulder clay. 


Correlative elevation of plains, proba- 
ble formation of Missouri Coteau along 
shore line. 


Simultaneous elevation of great plains 
to present levels; exclusion of the sea; 


cial period. formation of Lake Agassiz ; 


into present period. 


gradation 


Sir William Dawson would make three subdivisions of the Pleistocene 
period embracing (a2) Harlier Pleistocen: ; irregular depression of the 
continents, with cold climate and great local glaciers; (4) Mrddle 
Pleistocene ; submergence of coasts and re-elevation of interior plateaus, 
with milder climate—interglacial period; and (c) Later Pleistocene ; 
submergence of plains and general ice drift with local glaciers in moun- 
tains. The succeeding thirty pages of the chapter are devoted to the 
description of the deposits. 

“The third chapter is devoted to physical and climatal conditions. 
In the course of this the author introduces a map to show the distribu- 
tion of glaciated and unglaciated land, and of ice-laden and of ice-free 


234 LTE JOURNAL OF GHOLOGY. 


water during a typical stage of the Pleistocene period. Greenland, the 
Laurentian tract, the Adirondack, the northern Appalachian, and the 
northern Cordilleran regions are represented as glacial land. <A broad 
tract sweeping around the Laurentian belt covering the Great Lake 
region and a large portion of the great plains of Canada is represented 
as submerged beneath an ice-laden sea. So also is a large area embrac- 
ing Hudson’s Bay and the adjacent straits. ‘The Central American 
region is represented as extensively submerged and the equatorial waters 
of the Atlantic are represented as passing through to the Pacific. 

Under the head of causes of glaciation, the author rejects with 
emphasis the prevalent glacial hypothesis, insisting strongly upon the 
impossibility of so great an ice sheet reaching to so low a latitude. He 
quotes extensively from Woeickoff in support of his position. The ter- 
minal moraines of most American writers he refers to deposition “at 
the margin of a sea laden with vast fields of floating ice,” and thinks 
’ that some of the anomalies in their levels are due to differential eleva- 
tion. He explains the striation (in regions not occupied by glaciers, 
under his view) by referring them largely to the action of “pan ice” 
aided by tides, especially on sinking coasts, and subordinately to ice- 
berg action proper. His views on this point are well known. The 
very peculiar climatic conditions of the age are attributed to geograph- 
ical changes, but the discussion is not carried into detail, and we have 
been unable to form a definite conception of the supposed method of 
causation. 

The most valuable chapter, in our judgment, is that which relates. 
to Pleistocene fossils. There is an admirable collection of data in 
detaii, especially from the Lower St. Lawrence region—the richest of 
American fields in glacial paleontology. In regard to the relations of 
man to the glacial formations, Sir William Dawson apparently inclines 
to the interpretations of Professor Holmes. 

At the close of the work complimentary reference is made to How- 
orth’s book, ‘The Glacial Nightmare,” and the similarity of views there 
expressed to those of the present work approvingly noted. ‘Tactically 
we think this is an error, since conclusions associated with field experi- 
ence such as those of Dr. Dawson will be likely to be placed by geolo- 
gists in quite a different category from the dialectic lucubrations of a 
mere academic treatment. Support must be scant when “The Glacial 
Nightmare” is counted in. 


REVIEWS. 235 


The present writer dissents radically from the author’s fundamental 
conclusions and from his estimate of the present drift of opinion, but 
finds the book interesting and suggestive, and its contributions to Pleis- 
tocene paleontology notably valuable. T. C. CHAMBERLIN. 


The Post-Pliocene Diastrophism of the Coast of Southern Califorma. By 
Anprew C. Lawson. Bulletin of the Department of Geology, 
University of California Vol.1,No.4,pp. 11 5-160, plates 8-9. 


In this bulletin, Professor Lawson presents the results of some of 
his studies on the west coast of California. The essay concerns itself 
especially 1° with the coasts of San Diego and Los Angeles counties, 
and with the islands of San Clemente and Santa Catalina which lie 
a few miles to the west; and 2° with the coastal region from Santa 
Cruz to the Golden Gate. So far as concerns the southern region, 
the data are drawn principally from four localities. These are: a) the 
coastal slope of San Diego county,—the San Diego mesa; b) San 
Pedro Hill; c) San Clemente Island; d) Santa Catalina Island. 

The San Diego mesa is a terraced plain having a breadth of from 
twelve to eighteen miles. It is characterized as a Pliocene delta, made 
up principally of Pliocene sands and sandstones, but covered by a 
thin sheet of river gravels. The evidence for the statement that these 
gravels are of fluviatile origin is not given. The gravels are thought 
to have been deposited approximately at sea level. They now stand 
at a maximum elevation of nearly eight hundred feet. The inference 
is that an elevation of eight hundred feet has taken place along the 
coast of San Diego county since Pliocene time. Various marine ter- 
races at levels of seven hundred feet and less characterize the mesa. 

San Pedro Hill is an abrupt headland on the coast of Los Angeles 
county. Its slopes likewise show a series of marine terraces and sea- 
cliffs. The highest terrace on this headland stands at an elevation of 
1240 feet. There are many lower terraces on the San Pedro Hill, the 
lowest mentioned having an altitude of 120 feet. Through the higher 
terraces the streams have cut for themselves cafions ; but they flow over 
the lower terraces in shallowchannels. ‘This is evidence of the recency 
of the elevation marked by the lower terraces. Molluscan borings in the 
old sea-cliffs, up to an elevation of 1240 feet, may still be seen. 

From the relations of the Miocene to the Pliocene formations of 
the headland, it is inferred there was an “important interval of denu- 


236 TTT, OTK ALE TOT NG TE OMOGWe 


dation between the Miocene uplift and the depression which permitted 
the deposition on the lower flanks of the hill of the formations which 
paleontclogists recognize as of Pliocene age. ‘The recovery from this 
Pliocene depression is the uplift which is registered in the elevated 
strands of the hill.” The uplift following the Pliocene depression is 
regarded as Pleistocene. This conclusion is of course warranted, if 
the Pliocene strata involved are known to belong to the closing stages 
of the Pliocene period. Otherwise it does not appear that the con- 
clusion is a necessary one. Pleistocene strata are referred to as over- 
lying the Pliocene, and as belonging to a recent stage of the uplift. 
Between the Pliocene and the Pleistocene no evidence of subaérial 
denudation exists. . 

On the west side of San Clemente Island seventeen well marked 
terraces occur, the highest at an elevation of 1320 feet. These ter- 
races are from 200 to 1500 feet in width. ‘There are less distinct ter- 
races up to a height of 1500 feet. ‘The total amount of horizontal 
sawing which has been effected on the slopes of the island by wave 
action during its elevation through the last 1320 feet,” is more than 
two miles. 

Santa Catalina Island is of about the same size, trend, and height 
as San Clemente. It has a position midway between San Pedro Hill 
and San Clemente; but on Santa Catalina ‘“‘there is no trace of an 
elevated wave-cut terrace, sea-cliff, or strand line of any kind observ- 
able.” Furthermore, “The stream topography of the island is very 
much more advanced, z. ¢., much more ancient than that of either San 
Pedro Hill or San Clemente.” 

The absence of terraces and sea-cliffs cannot be attributed to the 
character of the rock, and their absence is in harmony with the con- 
dition of the stream valleys, which indicate that the island has not 
been below the sea in recent times; that is, “‘Santa Catalina has not 
been subjected to the uplift which has affected the two prominent 
insular masses, one twenty-five miles to the north of it, and the other 
twenty-five miles to the south of it.” Not only has Santa Catalina not 
been elevated while San Pedro and San Clemente were undergoing 
the great uplifts which have been mentioned, but it is believed to have 
actually sunk while these other land masses were being lifted. The 
evidence of sinking is found in the drowned valleys of certain parts of 
the coast, and in the falls and rapids which mark the termini of the 
streams of other parts. Santa Catalina would appear to be situated in 


REVIEWS. 237 


the trough of a syncline which has been actually sinking while the 
lands on either side were rising. 

The coast of the Bay of Monterey is also marked by a series of 
terraces. Four of them, the highest of which reaches an elevation of 
712 feet, are very distinct, and abut against sea-cliffs. Higher terraces 
extend up to an elevation of 1201 feet. ‘The river valleys also of the 
Santa Cruz region are found to afford evidence in harmony with that 
already cited from the regions further south. The general tenor of 
the evidence presented by this part of the coast is therefore in harmony 
with that presented by the more southerly region. Here also there 
has been a marked epeirogenic movement in recent times. 

On the peninsula of San Francisco, marine Pliocene rocks, having 
a thickness of more than one mile, are said to exist. It is believed 
that subsidence accompanied the accumulation of this great series. 
These strata now occur at an elevation of over 700 feet. Not only 
this, but the strata have been so tilted, and subsequent erosion 
has been so great, that the base of the series, as well as the top, is 
exposed at this elevation. The elevation is said to have been post- 
Pliocene. Of course this is true, if the uppermost Pliocene strata 
involved represent the close of the Pliocene period. 

According to the author, the relations of the Pliocene strata indi- 
cate great orogenic as well as epeirogenic movements in this region 
since their deposition. Montara Mountain is believed to have been 
produced during the orogenic event by which the Pliocene rocks 
(Merced series) were lifted into their present position. The granite 
axis of the mountain is regarded as the up-thrust base on which the 
Pliocene strata were laid down. All the adjacent younger strata dip 
away from this granite axis quaquaversally. While, therefore, the 
general structure of the mountain is comparable to that of a laccolite, 
it is, according to Professor Lawson, very different from it genetically. 

On the basis of the facts given in the paper, there would appear to 
be no ground for doubt concerning the main conclusions at which Pro- 
fessor Lawson arrives concerning the movements of the coast in recent 
times. On the basis of evidence presented, there might be some question 
as to the post-Pliocene date of all these changes of level, did not Pro- 
fessor Lawson define the Pleistocene so as to include them. He says 
(p. 159), “It is not an easy matter to delimit the Pliocene and Pleisto- 
cene epochs so that they shall correspond to the same divisions of the 
geological scale in the eastern part of the continent.... . The rea- 


238 TH JOURNAL OF GEOLOGY. 


son for this is that there has been no distinct break in the continuity 
of marine conditions throughout the epochs, only a gradual transition 
of conditions. In this gradual transition there was, however, a reversal 
of the epeirogenic movement of the coast from a process of depression 
to a process of uplift. This turning point of the disastrophic pendu- 
lum .. . . is believed to correspond well with the beginning of the 
Pleistocene.”” With this definition of the Pleistocene, of which we 
are not disposed to complain, there can be no doubt as to the age of the 
remarkable changes of level which Professor Lawson describes. It is 
to be hoped that at some future day he may give us an account of the 
corresponding phenomena along a greater and connected stretch of 
the California coast. The results announced in this paper purport 
to be no more than the results of a general reconnaissance of the 
regions described. 
Rouuin D. SALISBURY. 


ANALYTICAL ABSTRACTS OF CURRENT 
LITERATURE. 


Lin typisches Fyordthal. von Erich von Drygalskt. z. Z. GRONLAND. 
T4’ Pp. 


Dr.-Drygalski describes in detail a valley on the west coast of Greenland, 
one peculiarity of which is that there are three considerable depressions along 
its axis. These are occupied by lakes, some of which certainly, and all of 
which probably, have rock basins. Another peculiarity of the valley is that 
it crosses a narrow highland between two fjords. One end lies at the sea level, 
the other 211 m. above it, the slight drainage through the valley having a fall 
of this amount at the end of the valley. This latter point is nearly 100 m. 
‘below the divide in the valley, from which drainage flows in opposite direc- 
tions. The valley is about 5% km. long, about 1 km. wide, and has an aver- 
age depth of about 336m. While the valley is well above sea level, and 
therefore no fjord, it is pointed out that, with a relatively higher sea, it would 
become a fairly typical fjord. In the judgment of the author, the situation is 
such as to preclude the idea that the valley is a river valley, or that it isa 
river valley modified by ice action, and the author is ‘very much inclined to 
extend this conclusion to the fjords”” he hasseen. Dr. Drygalski advocates the 
view that this valley owes its origin primarily to the weathering of the gneiss 
in which it lies, and suggests that joint-planes, by determining the position of 
greatest weathering, determined also the position of the valley. Subsequently, 
after the valley had come into existence by weathering, the ice removed the 
weathered products, and an undetermined depth of solid rock below. The 
author leaves it to be understood that this is, in his judgment, a principal, if 
not the principal method by which the fjords with which he is familiar have 
originated. IXo IDs Sy 


A Preliminary Report on the Cretaceous and Tertiary Formations of New 
Jersey. By WiLLiaM BULLOCK CLARK, Annual Report of the 
State Geologist of New Jersey, 1892. 

This report presents the results of investigation conducted by Professor 
Clark and his assistants during the year 1892 upon the coastal plain forma- 
tions of New Jersey. The report, with a new geological map, covers the area 
of the U. S. Geological Survey atlas sheets of New Brunswick and Sandy 

239 


240 THE JOURNAL OF GEOLOGY. 


Hook. The text contains an historical sketch in which the work of past inves- 
tigators is briefly cited, and reference made to the various views upon the 
classification and correlation of the several formations. A second chapter 
is devoted to a consideration of the physical features of the coastal plain, fol- 
lowing which is an extended statement in regard to the stratigraphical char- 
acteristics of the formations foundthere. Although an attempt is made to make 
the classification of the deposits coincide, so far as it is possible, with the inves- 
tigations of the late Professor Cook, yet some changes of importance are con- 
sidered to be necessary. The name Raritan formation is proposed in place of 
the wholly inadequate term Plastic Clay, and the Upper Marl bed, which is in 
part Cretaceous and in part Eocene, is divided into Manasquan Marl and 
Shark River Marl respectively. The division of Yellow Sand proposed 
by Professor Cook is not held to be an independent formation, but is included 
under the Manasquan Marl. The Miocene is considered to be extensively 
developed in New Jersey. Although fossils have been found at only a few 
points, they are thought to be sufficient in number to indicate a series of depos- 
its several hundred feet in thickness and many square miles in surface exposure. 

In summing up his statements in regard to the relation of the several 
formations, Professor Clark says, “the deposits of the coastal series of New 
Jersey show complete conformity from the bottom of the Raritan formation to 
the top of the Upper Marl bed, while no wide-reaching dislocations of the 
strata have been observed at any point. The strike follows a nearly continu- 
ous trend of N. 50 E., while the dip is twenty-five to thirty feet in the mile to 
the southeast. Overlying the Upper Marl bed unconformably is the Miocene, 
which possesses the same general structural and stratigraphical features as the 
earlier members of the series.”’ 

The origin of greensand, which characterizes so many of the coastal plain 
formations of New Jersey, is fully considered, the results by Professors Murray 
and Renard, of the Challenger Expedition, being given with much fullness. 
The geological distribution of greensand is briefly reviewed, and the character 
of the New Jersey deposits more fully considered. Three colored plates are 
reproduced from the Challenger Expedition report on Deep-Sea Deposits, to 
illustrate the mode of formation of glauconite. IoD Ss 


The Pleistocene Rock Gorges of Northwestern Llinois. By Oscar H. 
HersHey. American Geologist, November, 1893. 


The object of this paper is to ascertain the length of the “deglaciation inter- 
val and perhaps interglacial epoch.” The ice of the maximum period of gla- 
ciation affected this region but slightly. In some cases the glacial sand and 
gravels were deposited in ridges transverse to the streams’ courses, thus dam- 
ming the streams and producing small lakes. Sometimes the barriers were so 


ANALYTICAL ABSTRACTS. 241 


high that the course of drainage was altered. The new valleys were cut in 
Galena limestone. The amount of cutting in the limestone since maximum 
glaciation is about equal to that in the newer drift in the vicinity of Lake 
Michigan. The later work has been going on, it is believed, about 7000 
years. It is estimated that erosion in the limestone of northwestern Illinois 
took place one tenth as fast as in the drift. On this basis 70,000 years 
have been required for the erosion accomplished in northwestern Illinois 
since the maximum period of glaciation. Long after the withdrawal of the 
maximum ice-sheet, a mantle of loess was spread over northwestern Illinois. 
The writer thinks that something like four fifths of the erosion accomplished 
since the withdrawal of the maximum ice-sheet was accomplished before the 
deposition of the loess. Fifty thousand years are considered a minimum, 
and perhaps twice that time not too great an allowance of time, for the erosion 
that took place between the time of the formation of the drift sheet in north- 
western Illinois and the deposition of the loess. Ilo Zo 18), 


LVotes on the Sea-Dikes of the Netherlands. By Pror. J. C. Smocx. 
(Annual Report of the State Geologist of New Jersey, 1892, pp. 
315-329). 

These notes are descriptive of the dikes at the Helder and at Petten 
in North Holland, and at West Kappele in Zealand. The breaks in the coastal 
dune ranges are occupied by them. The whole sea-front is protected by a sys- 
tem of jetties also. They are built on the strand and in front of the dikes— 
and check the currents which carry away the beach sands and tend to under- 
mine the dune hills at these localities. The dikes are essentially enormously 
thick walls of sand whose outer slope is at a low angle, and is faced with stone 
and further protected by rip-rap and by piling. The descriptive notes of the 
construction are illustrated with plans and vertical cross-sections. 

The application of a modified system of sea-dikes for the protection of the 
bluffs at Long Branch, New Jersey, follows. The reclamation of the tidal 
lands of the state is referred to, and the reclamation of the low-lands of Hol- 
land affords an instructive example. 

lo Co Se 


THE AMERICAN ANTHROPOLOGIST. 


An Illustrated Magazine of ninety-six pages, published quarterly 
under the auspices of the Anthropological Society of Washington. 

Among its recent Contributors are: Ad. F. Bandelier, Alex- 
ander Melville Bell, James H. Blodgett, Franz Boas, John G. Bourke, 
Daniel G. Brinton, Swan M. Burnett, A. F. Chamberlain, Frank Hamil- 
ton Cushing, J. Owen Dorsey, J. Walter Fewkes, Robert Fletcher, 
George Bird Grinnell, Albert S. Gatschet, John M. Gregory, W. T. 
Hams, J. N.S 7blewitt,) MW. dodge, Walter ij) Elotiman ) Werle 
Holmes, Walter Hough, D. S. Lamb, F. A. March, Otis T. Mason, 
Washington Matthews, W. J. McGee, J. D. McGuire, James Mooney, 
James C. Pilling, J. W. Powell, A. R. Spofford, A. M. Stephen, Cyrus 
Thomas, William Wallace Tooker, Lester F. Ward, James C. Welling. 

A Quarterly Bibliography of Anthropologic Literature, compiled 
by Robert Fletcher, is a valuable feature of each issue. 


SUBSCRIPTION, $3.00 PER ANNUM. 


AMERICAN ANTHROPOLOGIST, 
1315 CORCORAN STREET, WASHINGTON, D.C. 


Prominent among the many valuable fea- 
tures of THE BIBLICAL WORLD for 1894 
will be 


PRESIDENT HAREER'S 
IWELV EEE CTURES 
ON GENESIS 


which are now being delivered Saturday even- 
ings at the Memorial University Extension 
Centre, Oakwood Boulevard and Cottage 
Grove Avenue, and before the Faculty and 
students of the University Sunday afternoons. 
The first lecture appeared in the issue for 
January, 1894, and the others will follow in 
order of delivery in the successive issues of 
THE BIBLICAL WORLD through the year. 


SUBSCRIPTION PRICE $2.00 A YEAR. 
Send your subscription TO-DAY to 


THE UNIVERSITY PRESS OF CHICAGO, 


CHICAGO, ILL. 


THE 


(OCI AE OFC E OLOGY 


PoE VA Ve SSO. 


Wsus, QL, SVs VATS Ol Wells SiCOMUS Is 
CARBONE NOUS: Soir Wvr 


THE Lower Carboniferous Rocks of the east of Scotland have 
within the last quarter of a century attained great economic and 
geological interest from the oil-bearing shales they have been 
found to contain. The district around Edinburgh is one of 
great complication, and until the operations of the shale mines 
began large parts of the ground which is usually deeply covered 
with glacial drift were geologically but imperfectly explored. It 
is only recently that the chief oil shale districts have been 
mapped correctly, and the new edition of the geological map of 
the Edinburgh district, on which I have been engaged for sev- 
eral years tracing out the oil shale outcrops, etc., has only been 
published within the last six months. A detailed account of 
the structure of this area has not yet been published, and 
beyond a few short papers by myself and others in various sci- 
entific journals, nothing of importance has been written on this 
interesting subject. 

The Carboniferous system of Scotland is broadly divisible 
into the following groups: 

. Coal Measures, with the most important coals. 
. Millstone grit, chiefly barren sandstones. 


ty SW 


. Carboniferous Limestone Series, with beds of limestone above 
and below, and shales, sandstones, etc., interbedded with seams 
of excellent coal in the center. 

I. Calciferous Sandstone Series, with sandstones, estuarine lime- 

stones, marls, seams of oil shale and occasional impure coal, the 

243 


244 TLE JOOKINAL VOT ANGIOL OG: 


base of the series consisting of coarse red sandstones, shales and 
marls resting on the Old Red Sandstone. 

The oil shales of Scotland are confined almost exclusively to 
the ‘Calciferous sandstone” strata in the Edinburgh district, 
and the principal seams occur in West Lothian, where the most 
important oil works are situated, about twelve miles west of the 
Scottish metropolis. 

Broadly speaking, Edinburgh is situated on a great anticline, 
in the center of which there rises a ridge of Silurian and Old 
Red Sandstone rocks, partly igneous and partly sedimentary, 
whose general strike is northeast and southwest. The hard vol- 
canic strata and igneous intrusions in these older rocks have 
produced most of the pictureque ranges of hills in the vicinity 
of Edinburgh, and the softer beds in the higher parts of the series 
dip away, with many complications, from either side of the 
central axis. To the east of the Pentland ridge the inclination 
of the beds is very high, and comparatively regular, and conse- 
quently the whole thickness of the calciferous sandstone series 
can be traversed in a short time. There is also here a large 
fault running along the base of the hills which conceals the low- 
est of the calciferous series of rocks and brings up the old vol- 
canic beds against the upper parts of the oil-bearing strata, and 
indeed at one place the dislocation has been so great that the 
calciferous rocks with their oil shales are almost entirely hidden, 
and the upper beds of the Old Red Sandstone abut almost 
directly on the base of the marine limestone series. 

The Carboniferous limestones along this line, with their 
interbedded coal seams, are inclined for long distances at the 
same high angle and plunge at places almost vertically down- 
wards beneath the long and regular trough of Dalkeith Coal 
Measures, from which they emerge five or six miles farther 
east at a much lower inclination. 

To the west of the Edinburgh anticlinal the structure of the 
district is much more complicated. The Calciferous rocks 
spread out for fifteen or sixteen miles in a tumultuous sea of 
undulations, basins and folds cut up by multitudes of faults, and 


OIL SHALES—SCOTTISH CARBONIFEROUS SVSTEM. 245 


traversed by numerous necks, sheets and dykes of intrusive 
igneous rock, to map which, even with the aid of copious 
mining information, is often a task of the greatest difficulty. 
The rapid thinning and thickening of some of the members of 
the series also adds an element of difficulty to the elucidation 
of the structure of the district, and although many hundreds 
and even thousands of borings have been made in search of 
oil shale and other rocks, there are places where, in the absence 
of surface exposures, the structure of the area has still to be 
ascertained. 

The total thickness of the Carboniferous Limestone series 
of Mid and West Lothian is about 2,000 feet, and that of the 
upper or oil shale division of the underlying calciferous series is 
a little over 3,000 feet. Beneath the oil shale series there is a 
group of shales, fire clays and gray sandstones, one of which, 
formerly quarried very extensively at Craigleith, supplied nearly 
all the celebrated freestone from which a large part of the New 
Town of Edinburgh was built. Owing to its great hardness 
and cost of working the Craigleith stone has now been nearly 
given up and is only used where great strength is wanted in 
house architecture, or for export to America, where it appears 
to be used occasionally for special work. This middle division 
of the Calciferous Sandstone series appears to be about 3,000 
feet thick, and the red beds which lie below cannot be much 
thinner, so that 9,000 feet may be taken as the approximate 
distance from the top of the Old Red Sandstone to the highest 
part of the Oil shale series in this locality. 

Dealing now in greater detail with the Oil shale group of 
rocks, it may be noted, first, that the whole series has a fresh 
water or estuarine character, and contains few or no strata of a 
marine type. There are numerous thin bands of concretionary 
unfossiliferous limestone, and one well-marked bed of richly 
fossiliferous estuarine limestone of workable thickness. This 
rock—the Burdiehouse Limestone—in addition to fresh water 
shells, contains fish plates, teeth, etc., and many plant remains 
such as lepidodendron and sphenopteris, and is at places directly 


240 THE JOURNAL OF GEOLOGY. 


covered by a bed of black bituminous shale of inferior oil- 
producing quality. The series is also characterized by numer- 
ous well-marked beds of unfossilferous red, green and gray 
marl, the origin of which is not very clear, but as the marl is 
seen at places to contain pieces of felspathic volcanic ash, it 
seems reasonable to suppose that it may be made up in part at 
least of impalpable mud derived either from volcanic dust or 
from the disintegration of some old volcanic area which has now 
disappeared from view, but which formed part of the ancient 
mainland from which the other sediments were derived. There 
is no distinct evidence of volcanic action during the greater part 
of the Oil shale period in the Lothians, and the numerous ash 
necks which pierce the strata were probably connected with the 
extensive outbursts which took place during the subsequent Car- 
boniferous Limestone period. Many beds of gray and yellow 
sandstone are found interbedded with the oil shales as well as 
impure coals, fire clays, and non-bituminous carbonaceous shales 
—the ‘‘blaes” of the Scottish mines, in which plant remains, and 
fresh-water molluscan forms are at places found in abundance. 

The Scottish Oil shales are simply beds of very fine impalpa- 
ble clay shale highly impregnated with hydrocarbon, easily dis- 
tinguished in the field by their resistance to the disintegrating 
action of the weather, thin brown streak, and the facility with 
which they can be cut and curled up with a sharp knife. The 
texture is at times tough, almost leathery, and thin pieces are 
slightly flexible and easily distinguishable from ordinary black 


5) 


carbonaceous ‘“‘blaes”’ with which they are often closely asso- 
ciated. When lit with a match oil shale burns, as a rule, brightly, 
leaving a finely laminated skeleton of ash after all the hydrocar- 
bon has been exhausted. On distillation the yield of oil varies. 
Good shales should give, per ton, at least thirty gallons of crude 
petroleum, as well as enough ammonia to produce, when neu- 
tralized with sulphuric acid, from ten to fifty pounds of sulphate 
of ammonia. This product is often as valuable as the oil, and 
much skill has been employed in the construction of retorts to 
extract it completely. The crude oil when refined gives various 


OIL SHALES—SCOTTISH CARBONIFEROUS SYSTEM. 247 


products, such as tar, naphtha, paraffin, light illuminating and 
heavy lubricating oils, and the oil industry of the Lothians was 
for more than a quarter of a century a source of great profit and 
employment to the capitalists and operatives of the district, but 
of late years the severe competition with foreign producers has 
made most of the works quite unremunerative. The thickness 
of the oil shale beds varies considerably from place to place, 
and it is quite common to find a good seam thinning out in 
one district and passing into ordinary carbonaceous shale, or 
disappearing altogether, while another seam above or below it 
may improve in quality in proportion as the first deteriorates. 
The Broxburn shale—the richest seam in the Broxburn district 
—varies in thickness from about two and a half to eight feet, 
and the Dunnet shale reaches at places a workable thickness of 
thirteen feet. 

An interesting phenomenon is observable at some places 
where the strata have been heated by igneous intrusions. In 
these cases if an oil shale bed has been affected by the heat, 
partial distillation has followed, and the surrounding rocks, 
including the eruptive sheet itself, have become impregnated 
with the hydrocarbonaceous ingredients expelled from the 
shales. In a recent diamond boring a core of the eruptive 
dolerite was brought up from a depth of over 600 feet, trav- 
ersed by veins of solid paraffin, which melted when the rock was 
laid in the sun, and at the outcrop of this intrusive sheet it is 
found to contain cavities filled with tarry matter and to 
give off a strong bituminous odor when freshly broken with the 
hammer. This eruptive sheet has forced its way for miles 
through strata adjoining the Broxburn shale, and whenever it 
has touched or even approached the shale the seam has of 
course become quite worthless economically. The well-known 
sandstone of Binney, which is located some fathoms below the 
Broxburn shale, has long been known to contain veins of ozoce- 
rite or an allied hydrocarbon, and the quarrymen used formerly, 
when the rock was extensively worked for building and monu- 
mental purposes, to make black candles of the substance, some 


248 THE JOUKNAL OF GHOLOGV: 


of which are still preserved in the Science and Art Museum in 
Edinburgh. There can be little doubt that this ‘‘mineral’’ owes 
its origin to the distillation of the bituminous matters by the 
igneous intrusions in the vicinity of the overlying oil shale. 

The oil shales occur within an area roughly twenty miles in 
diameter. On the north shore of the Firth of Forth only one 
seam of workable quality is known, and all the others have 
apparently disappeared and become replaced by more arena- 
ceous rocks, while in the Lower Carboniferous deposits in other 
parts of Scotland no oil shales of any value have been yet dis- 
covered. These valuable deposits appear to, have been found 
in broad lagoons into which vegetable matter was brought in a 
very fine state of division, and laid down along with a small 
quantity of inorganic silt under conditions of great tranquillity. 
That the hydrocarbon is however sometimes of animal origin is 
clear from the quantity of cyprids that make up some of the 
shales. Large plant remains are rare, but beautifully preserved 
fronds of sphenopterts affints, and other ferns are abundant in 
some of the beds of oil shale. There cannot have been currents 
of any strength sweeping through the lakes of the Scottish oil- 
shale period, otherwise the light organic particles would have 
been at once swept away, and this order of things must, with 
periodical interruptions, have obtained within the shale region 
for a long succession of ages, during which deposits accumu- 
lated to a depth of over 3,000 feet. 

Liquid petroleum has been occasionally found exuding in 
small quantities from the joints of these sedimentary rocks, and 
there is at St. Catherines, about three miles south of Edinburgh, 
a spring situated on the line of the great fault east of the Pent- 
land axis already referred to, known for many centuries as the 
Balm Well, whose surface is covered by a film of mineral oil 
derived no doubt from the slow distillation of the oil shales on 
the downthrow side of the dislocation. We cannot, however, 
boast of anything like the famous oil wells of Pennsylvania, 
which I had the pleasure of visiting in 1891, and even were 
there rich oil sands among the Califerious sandstones of the 


OIL SHALES—SCOTTISH CARBONIFEROUS SVSTEM. 249 


Scottish Lothians, the exceeding faulted and disturbed nature of 
the Carboniferous system in this locality would effectually pre- 
vent the circulation underground of any quantity of fluid hydro- 
carbons except within extremely limited areas. 

The following is a general section of the oil shale series west 
of Edinburgh: 


FEET. 
Strata below base of Carboniferous Limestone series about 400 
Raeburns Shale, 3 to 4 feet strata, = - - - 190 
Mungals Shale, about 1 ft. g ins. strata, - - = 170 
Coal and Gray cypride Shale 2 ft. ‘‘ Houston Marl” group 200 
Strata laminated sandstones, - - - - - 240 


Fells Shale, 3 to 5 feet, “ Broxburn Marl”’ group, 80 to 270 
Broxburn Shale 2% to 8 feet, ‘‘ Binney Sandstones” and 
strata, = = S = - 2 - = 450 
Dunnet Shale, 6 to 13feet, strata chiefly shales, fire clays, etc. 400 
Barracks Shale, resting on the estuarine Burdiehouse Lime- 
stone, Io to 50 feet thick at places, strata about - 780 
Pumpherston Shales, about 6 feet worked. 


Apparent thickness of Oil shale series, —- - = BOO 


Henry M. CapeE.t. 


Weld, CISIVANCIOWS III Ole Isls IOAN lENULILS = 


As 1s well known, the Black Hills District was surveyed by 
the party in charge of Professor W. P. Jenney in 1875, the geo- 
logical report being written by Professor Henry Newton, whose 
death occurred two years later. The report, edited by Mr. G. 
K. Gilbert, was published in 1880 by the U. S. Geographical and 
Geological Survey of the Rocky Mountain Region in charge of 
Major J. W. Powell. The peculiar and interesting geological 
features of this remarkable outlier of the Rocky Mountain range 
need not be set forth here further than to say, that on all sides 

-atter leaving the central nucleus of eruptive rocks sedimentary 
deposits occur with diminishing dip in an ascending geological 
order. First, there is a narrow ring of Potsdam sandstone; then 
a wide belt of Carboniferous limestone je Mext/ an! eneirelmns, 
trough, aptly compared by Professor Newton to a moat, of red 
sandy gypsiferous clays, in which is included a purple limestone 
terrace, all of which is supposed to be Triassic and to be the 
equivalent of the ‘“‘ Red Beds” of more southern regions; skirting 
this is a very narrow border of highly fossiliferous light colored 
Jurassic clays or marls; then come the foot-hills, which consist 
of Cretaceous sandstones and shales referred by Professor New- 
ton to the Dakota, No. 1, of Meek and Hayden’s section; these 
slope back to the dark shales of the Fort Benton group, which 
are succeeded by higher Cretaceous beds that extend to the 
plains and pass under the Bad Lands of the White River forma- 
tion. 

The belt of Cretaceous, which lies outside the Red Beds and 
Jurassic and forms the foot-hills, constitutes an elevated rim 
with an escarpment at its inner margin rising abruptly above 
the Triassic trough, the Jurassic exposures being often confined 
to the lower part of the escarpment. This cannot be better rep- 


‘Published with the permission of the Director of the U. S. Geological Survey. 
250 


TDD OT RACE OOS MMM OF LHI BEACK I/ILES: 251 


resented than in the following figure copied from Professor 
Newton’s report :? 

At that date the opinion widely prevailed that there was no 
Lower Cretaceous in North America. The Shasta, Kootanie, 
and Comanche groups were unknown, the Potomac of Virginia 
was supposed to be ‘Upper Oolite,” and the Iron Ore Clays of 
Maryland and Plastic Clays of New Jersey were classed as Weal- 
den and referred to the Jurassic. Meek and Hayden had 
been unable to find any Cretaceous deposits lower than No. 1 of 


Fred Valley. 


area 
2 WAN HRN 8 


Fic. 1.—Ideal section across Red Valley on Amphibious Creek. 
Carboniferous. 
Red sandstones and clay (Red Beds). 
Purple limestone (Red Beds). 
Red clay with gypsum (Red Beds). 
Jura. 


! 


Dm Bw DN H 
Sides te ered Rate oy 


Cretaceous sandstone capping the foot-hills. 


their famous section, and this was believed to be the oldest Cre- 
taceous deposited on this continent, which was supposed in some 
way to have been out of water during the entire period that sep- 
arated this from the Jurassic. 

My attention was first attracted to the Black Hills by a letter 
received at the Smithsonian Institution in February, 1893, from 
a resident of Hot Springs, South Dakota, inclosing photographs 
of certain petrifactions found in that vicinity which he said had 
beenmycalled \Gycadsy? ihe letter and photographs were 
referred to me on the presumption that these objects were of 
vegetable origin. I at once perceived that they were fossil 
cycadean trunks closely resembling those collected by Tyson in 
1860 in the Iron Ore Clays of Maryland and named by Professor 
Fontaine Zysonia Marylandica, and, therefore, also similar to the 
forms found by Mantell and others in the early part of the cen- 


*Geol. Black Hills of Dakota, p- 141, fig. 20. 


252 Wield. JOLIN AE (OW? CIROIL/OEG LS, 


tury in the Purbeck beds on the Isle of Portland and at other 
points in the South of England. Being greatly interested in the 
discovery, I recommended that the proprietor be requested to 
send on a specimen for examination. The request was complied 
with, and the specimen proved to be all that I had expected. I 
therefore made the further recommendation that negotiations be 
entered into with a view to the purchase of the collection of six 
specimens which were offered for sale. This was also successful 
and the collection arrived in May.* One of the chief features of 
these specimens is the great size of some of them, the largest 
measuring 30 inches in height, 2 feet in its longest diameter, and 
weighing goo pounds, thus far exceeding anything of the kind 
hitherto known from any other part of the world. 

Fossil remains of cycadean trunks range from the Upper 
Trias to the Lower Cretaceous. A number have been found in 
the clay shales of Italy which have been referred to the Ceno- 
manian, but will probably be found to be lower. Hot Springs is 
located on the Red Beds in the valley of the Minnekahta creek, 
or Fall River, and it would have been natural to suppose that 
they cycead: truni<s) hade come either! trom) hese wor iromumeme 
Jurassic which borders it, had it not been stated that they were 
found ‘‘on a high hill.” My interest was of course strongly 
aroused to know the stratigraphical position of the beds in which 
they occurred, and therefore early in September I made an expe- 
dition to the region for the purpose of determining it if possible. 
I had previously corresponded with Mr. F. H. Cole, of Hot 
Springs, from whom the specimens had been purchased. I had 
also written to Professor Jenney, who was then at Deadwood, 
and who kindly consented to join me on my arrival and aid me 
in the investigation. After considerable search and some diffi- 
culty the locality was at length found. It is some four miles 
southwest of Minnekahta Station, about two miles west of 
Minnekahta Creek, which here has a northward course, on foot- 
hills one and a half miles east of the divide between that and 
Red Valley. A deep cafion lies to the south, which has an east 


tSee Science, Vol. XXI., No. 543, June 30, 1893, p. 355. 


TLE CTE ANCHO S Kil, OFs HE BLACK HHIEES: 253 


course and opens into the Minnekahta Valley. The locality is 
on the southeast slope, just below the top of the flat-topped 
spur-ridge and near the abrupt descent into the cafon. From 
this point northwest to near the crest of the divide the slope is 
moderate and nearly uniform. 

The accompanying sketch-map (Fig. 2) showing the drain- 
age of the region north of the south fork of the Cheyenne river, 
the Minnekahta Valley, and part of the Red Valley, will enable 
the reader to understand the general character of the country 
covered by this reconnaissance. 


&S 
v& 


t i 
= Ae ae % and 


: AC. ! 
a OT SPRINGS] *3. 44 
sy 332 Minneka hte Nee . = SUG 
S y 
S25 | PARKERS PK. ( 


ud r, 


Mt 
fe, 


\.CHe e ne Fall's ; 


Cascade Springs 
s 


Fic. 2.—Sketch-map of a portion of Fall River County, South Dakota. 


AB. Section No. I. CD. Section No. II. 
I. Cycad bed. 4. Upper leaf bed. 
2. Fossil forest. 5. Lower leaf bed. 
3. Plant bed. 


At the foot of this crest on the same (southeast) side, and 
about one and a half miles northwest of the cycad locality, occurs 
an extensive fossil forest. The wood is all completely silicified, 
and consists of prostrate trunks of various sizes and lengths and 
an abundance of smaller fragments, many of which are scattered 
about on the sloping plain a long distance below the actual hor- 
izon at which they were petrified. At that horizon many still 
remained apparently undisturbed, and in one place a trunk eight 
inches in diameter was seen projecting several feet from beneath 
the massive sandstone ledge. To the south of this point is a 


254 THE JOURNAL OF GEOLOGY. 


saddle, beyond which the crest of the divide is lower, and here 
the forest is seen to the best advantage. The most prominent 
object is an immense trunk, thirty inches in diameter and twenty 
feet long, lying where it fell at no very remote date, having 
broken from its roots at the surface of the ground, leaving por- 
tions of the stump still exposed. The entire root could proba- 
bly be exhumed. About the present trunk the lines of splinters 
and smaller fragments clearly indicate the character of its 
branches and show that these branches remained attached at the 
time it fell. A considerable amount of silicified wood occurs 
also at the same locality as the cycads, obviously preserved by 
the same influences that preserved the latter. The slope from 
the fossil forest to the cycad bed is about the same as the dip of 
the strata. It is therefore probable that both occur approxi- 
‘mately at the same horizon. The whole of this region, includ- 
ing the entire crest of the divide and extending to the bottom of 
the cafion below the cycad bed and far to the southeast, consists 
of the series of sandstones that have been treated in the Black 
Hills report as the “Dakota Group.” 

The great improbability that the cycads could have lived in 
the Dakota period, or Upper Cretaceous, led us to undertake an 
investigation of these rocks with a view to the possible discovery 
of additional evidence of their age. No other fossil remains 
than the wood and cycad trunks could be found in the immedi- 
ate vicinity or anywhere on the outer slope of the Cretaceous 
rim. The crest above the fossil forest consists of harder sand- 
stones, chiefly massive, which may be traced far around the 
Hills, and which form the upper part of the abrupt escarpment 
above the soft Jurassic and Red Beds. Passing over this to the 
northwest we descended into the first lateral cafon entering Red 
Valley from the northeast. The Jurassic is passed through and 
the Red Beds fairly entered in the descent. Fifty to seventy- 
five feet above the Jurassic contact and 175 to 200 feet below 
the summit of the crest, argillaceous shales with some carbon- 
aceous matter occur interstratified with the sandstones, and at 
this level, partly in the shales and partly in the rocks, a few fos- 


THE CRETACEOUS RIM OF THE BLACK HILLS. 255 


sil plants were found and a small collection made. They bore 
no resemblance whatever to the flora of the Dakota Group, but 
consisted chiefly of ferns with a few coniferous twigs and possi- 
bly cycadean remains. In short the flora, so far as I could 
judge, was rather that of the Lower Cretaceous. 


Fic. 3.—Section across the divide between Red Valley and Minnekahta Creek. 


I. Red Beds. 12. A, Cycad Bed. B, Fossil Forest. 
2-7. Jurassic. 13. Equivalent of Quarry Sandstone in Section No. II. 
g. Plant Bed. 


The entire section, from the Red Beds at the bottom of the 
cafion to the summit of the crest forming the divide, was care- 
fully measured, the position of the fossil forest bed, the cycad 
bed, and the plant bed, fixed as nearly as the circumstances 
would permit, and all the variations in the nature of the strata 
indicated. The section, as determined on the spot, is as follows: 


SECTION NO. I. 
Dakota of Newton. 275 Feet. 


13. Massive pinkish sandstone approaching a quartzite locally.............. 75 feet 
12. Grayish white sandstone with silicified wood and cycads................ 30 feet 
Tit, IPM eraGl jelllonvisln Sone SarnGlstomns 55 o56a00cssccdcsuc0cgdcnaas sodc 75 feet 
LO, Clays wrt sinebi@aibioins Or COBll s.c¢ ccgc0gc0d0c0oune neo aa00 buGD sO0E OE 20 feet 
g. Soft pink and gray sandstone with ferns and other plants............... 25 feet 
8. Reddish, pinkish, and yellowish brown massive cross-bedded sandstone.. 50 feet 
Jurassic. 220 Feet. 
To Olinne grax Clas ancl seunclsiwome singles 5545 60h0 00600000 00000004 anne adac 50 feet 
Onmleichtenedesottesand Stomepaye ta cals cys sere ernst a tace nce eidihne sae 60 feet 
5. Olive gray clays and gray sandstone shales........................... 40 feet 
Ane Olive rdialo ucla. vant ciara rete els) yobs ieilsigs cst aie iettsareneiie nese lslelainy lapels Wile cela eee 20 feet 
Beuellowesandstometshaleswysreirse siaecccsa cree icic/oeneletoy ecole forget eee cau ale 20 feet 
2, Olline cheald Clanie|bcd comnts norco mes oetean 600 boo ub op oboo OM once Ob mE 30 feet 
Red Beds (Trias). 
1. Red marls, conformably exposed at bottom of cafion.................. 20 feet 


This section may be represented diagrammatically in Fig. 3. 


256 IVES JOU AN ALL, (UP CIR OWMOGA, 


The Minnekahta Creek, or this southern fork of it, after 
flowing north through the Cretaceous, enters the Red Beds a 
little south of the Minnekahta Station, after which it bends to 
the eastward and follows the strike to Hot Springs. Below this 
point it takes a southeasterly course, and soon reénters the Cre- 
taceous, cutting entirely through the sandstone and entering the 
dark Fort Benton Clays a short distance below the cataract at 
the électric light plant nearly five miles from Hot Springs at 
Evans Siding. Evans Quarry is just above this point on the left 
bank. At the last named place Professor Jenney had formerly 
obtained dicotyledonous leaves, and it was his impression that 
these might have come from near the horizon of the cycad bed. 
This region presents an admirable opportunity for measuring a 
_section of the Cretaceous, which it was very desirable to do for 
comparison with the one last given. 

The distance at the bottom of the valley from the Jurassic 
contact to the Fort Benton is about three miles, and the dip, as 
the section shows, is over 100 feet to the mile. The quarry is 
about one-half mile from the point where the sandstones pass 
under the Fort Benton shales. It has a thickness in workable 
stone of about 60 feet, and is immediately capped by 40 or 50 
feet of softer material. It dips very rapidly to the southeast so 
as to come down to the stream at the electric light plant, and 
constitute the rock over which the cataract flows and through 
which the water has here worn deep longitudinal grooves. Imme- 
diately over these rocks and resting upon them there is a bed 
some Six or eight feet in thickness of dark clay and argillaceous 
shales with carbonaceous matter and some impure coal. In this 
bed was found a great abundance of more or less comminuted 
vegetable matter, with short fragments of culms or reed-like 
plants not determinable. There also occurred in certain of 
the shales a few tolerably well preserved dicotyledonous 
leaves, some of which are determinable. They were at least 
sufficient to indicate with practical certainty that this stratum 
belongs to the Dakota Group of Meek and Hayden (QN@, 1). 
A small collection was made at this point, viz., at the cataract 


IIE MCKIS ICA CIZOUUS, KIM SOV ISSR. SICA OK a ILI OS, 257 


over the hard sandstones on the right bank of the stream above 
the electric light plant (5, Fig. 2). 

This bed was easily followed to the quarry, where it consti- 
tutes the overlying mass which it is necessary to remove in order 
to uncover the workable sandstone below. At this point the bed 
also contains layers of soft white sandstone more or less massive. 
Large blocks of this had been thrown down and lay strewn at 
the foot of the quarry. On the surfaces of these and more or 
less scattered through their mass were impressions of dicotyle- 
donous leaves of Dakota types. The shales were also found in 
places above the quarry, and some of these yielded very good 
Soeoumems (41 lie, 2). 

The massive sandstone of the quarry is entirely barren so 
far as could be ascertained, and no fossils were found at any 
point lower than the bed that overlies it. For a long distance 
on both sides of the cafion it forms the crest of the ridge, pre- 
senting a more or less abrupt escarpment of from 25 to 75 feet. 
Below it, higher up the stream, beds of softer sandstone, argil- 
laceous shales, and carbonaceous layers with impure coal seams, 
all highly charged with gypsum, come down to the bed of the 
stream, and are finally seen resting upon the Jurassic clays, which 
in turn overlie the Red Beds. Some distance below Hot Springs 
the Cretaceous can be seen at the summit of the cliffs, with the 
whole thickness of the Jurassic below them and the Red Beds at 
the base. At and about Hot Springs there are some heavy beds 
of conglomerate about which little seems to be known. 

The following is the Cretaceous section as measured: 


SECTION NO. II. 
Fort Benton. 


11. Grayish black clays with layers of ferruginous concretions, extending to 
the south Fork of the Cheyenne River—contact conformable. 


Dakota of Newton. 339 Feet. 


10. Pink sandstone, mostly thin-bedded, with ripple-marks and fucoid-like 
BUTANE SST OMS rene meer eter cntieenl a erica se Shee ampere matali ebah st acate akausit aide 30 feet 

g. Soft black shales with traces of carbonized plant remains and some frag- 
MIKE TIESHO MphOSSUIM WOO Gen red vay secee ta ile ie: cago Sa RI es Aa esede fe mate ates 15 feet 
Smbinkwandyonayrsamadstomes suse am ci tenes a aman s siata onayayi niece eke 30 feet 


258 -_ THE JOURNAL OF GEOLOGY. 


7. Clay shales and sandstones, the latter sometimes white, all plant bearing, 
much comminuted vegetable matter, matted beds of swamp plants, and 


well-preserved dicotyledonous leaves of Dakota types, determinable... 10 feet 
6. Black clay full of carbonaceous matter, with locally six inches of impure 

(OO EaN ca al aerate ntigel Na etn get ete deta A teers Sal ite ata tear esta tact abet os AN cs 4 feet 
5. Quarry sandstone, massive, light pink, soft, weathering iron-brown...... 60 feet . 
4. Sott, yellowish and) reddishysandstomes) 52-4). s ee see ae a 100 feet 
3. Drab-colored clays with carbonized vegetable matter and gypsum crystals, 

nierdoecleleGl \yialtln yelllon? SEINGISKOINES 5454 4050 6000 0050 0da0 00805000000 30 feet 
2. Soft yellow and reddish sandstones with some clay layers.............. 60 feet 

Jurassic. 


I. Olive gray, drab or bluish clays with reddish and yellowish sandstones, to 


Fic. 4.—Section through Minnekahta Caiion. 


I. Jurassic. 

. Equivalent of plant bed in Section No. I. 

. (Upper portion). Equivalent of cycad bed in Section No. I. 
. Quarry sandstone. 

. Dakota leaf bed. 

. Fort Benton. 


aN Mm B 


It will be seen by a comparison of these sections that they 
are in substantial agreement, although no effort was made to 
make them so. The crest of the divide in section I represents 
the Quarry sandstone of section II, which was probably consid- 
erably thicker at this point, fifteen feet more being found, exclu- 
sive of erosion, but these rocks were often much harder in section 
I, and no quartzitic rocks were seen in the quarry. On account of 
the debris thrown down from the quarry and other obstructions, 
it was not possible to examine the next member below with as 
much care as was desirable in view of the fact that it seems to 
be the equivalent of the cycad and fossil forest horizon of section 


LiL Oe OR OTS IMM OM TEV BISA CK FILE E SI 250 


I; z.¢., No. 12 of section I corresponds to the upper 30 feet of 
No. 4, section II. 

At Minnekahta Station, in an ornamental heap of various min- 
erals and rocks from the Black Hills, there were a number of 
fragments of cycads and fossil wood. We were told that these 
came from a ridge two miles to the southeast of the station that 
rises above the Red Beds and shows at its base low buttes and a 
considerable thickness of Jurassic. This was not visited, but it 
was evident that the summit of this ridge was formed by the hard 
sandstone No. 1 of section I (No. 5 of section II), which is con- 
tinuous to Evans Quarry. The position of the cycad and fossil 
forest bed here is doubtless the same as on the opposite side of 
the valley where it was studied. 

The occurrence of two other specimens of cycadean trunks, 
though apparently belonging to a different species, in the same 
general horizon on the east side of the Black Hills, and of silici- 
fied wood in the northern districts, seems to indicate that the 
same relations obtain on all sides, and this will probably be found 
to be the case. 

The fossil plants of the lower horizon were sent to Professor 
Fontaine for determination, and the following extracts from his 
report upon them will show that my interpretation of their sig- 
nificance at the time of their discovery was for all practical pur- 
poses correct. 

“The best preserved fragments are scattered leaflets, and the 
summits of the ultimate pinnze of ferns, which are the parts of 
those plants which have great value in fixing species. The fol- 
lowing are the plants: 

“7, The summits of ultimate pinne of a fern, which is decid- 
edly like Asplenium Dicksonianum Heer, from the Kome beds of 
Greenland. It has also something of the character of the widely 
diffused Potomac plant, 7hyrsopteris rarinervis, but is, I think, 
nearer Heer’s plant. 

“2. Some ends of the ultimate pinne of a small fern with the 
facies of a Gleichenia. This is nearest to Heer’s Gletchenia Zippet, 
from the same Kome beds, but the pinnules are rather more acute 


260 TLLLL A /[O) SLAN ALSO LING TA OIGO GM 


than most of those of that plant, and indicate that those on this 
plant, lower down, are somewhat larger than those of G. Zippez. 
The form is also something like Aspzdium heterophyllum, of the 
Potomac, but seems to be smaller and more delicate. It may 
however be the same. 

‘2. The most common fossils are fragments of detached leaf- 
lets and one entire leaflet, of a plant which is strikingly like a 
Neuropteris of the coal measures (V. flexuosa). Jam pretty sure, 
however, that it is a Glossozamites, a form of cycad that has leaf- 
lets which, in form and nervation, closely resemble Neuropteris. 
This, if a Glossozamites, has leaflets proportionately broader and 
shorter than any known to me, and it is probably new. 

“4. There are a number of imprints left by organisms which 
in shape, dimensions, etc., would agree with fragments of the 
leaves of Pinus, or of Leptostrobus, but as nothing of the nerva- 
tion is shown, it is not possible to say which they are. Some of the 
imprints are too deep and open, apparently, to have been formed 
by leaves. They seem to have been straight, slender stems. 

“Tt will be seen from this account that the plants, so far as one 
can judge from such imperfect material, indicate a lower Creta- 
ceous and Neocomian age, with rather more resemblance to the 
Kome than Potomac phase or grouping, but it is by no means cer- 
tain that the Potomac grouping is not nearest to that here shown.” 

Thin sections of some of the silicified wood have been made 
and microscopically studied by Professor F. H. Knowlton. He 
reports the results as follows: 

“The structure of this wood is very finely preserved, and a 
glance suffices to show that it possesses the Araucarian type 
and represents, with little question, an undescribed species 
of the genus Araucarioxylon. The wood-cells are provided 
with two rows of alternating hexagonal pores on the radial 
walls, which nearly, or in some cases, quite cover the walls. The 
medullary rays are composed of a single layer of thin, short cells, 
each of which is covered on the radial side with numerous fine 
dots or punctations. The rays are from one to bout twenty 
cells high, the average number being perhaps eight or ten. A 


IEE (CIID WA CIROUS. IMM (HE Sie EB Sif LOG SaG Posy. 261 


large number are composed of only one or two cells. The annual 
rings are rather indistinct, yet can be made out. 

‘‘As faras I now know, only two species of Araucarioxylon have 
been described from the United States, A. Avzzonicum Ka., from the 
Triassic or Lower Jurassic of New Mexico and Arizona, and A. 
Virgimanum Kn., supposed at first to belong to the Potomac 
formation, but now known to be from the Trias of Virginia. 
These species differ markedly from the one under discussion. © 
With the A. Avizzonicum it has almost no points in common, while 
it differs from the A. Vzrgintanum in important particulars.” 

The only sections of the fossil wood that have yet been made 
were cut from a specimen taken from the cycad bed proper and 
not from the principal fossil forest, but it often happens that 
only one species can be found in such a forest. It is therefore 
probable that the same structure would be shown by the other 
specimens. I confess to a little surprise at finding that this 
structure represents the Araucarian rather than the Sequoian 
type of conifers, since, in the east at least, these two types char- 
acterize the Trias and Potomac respectively, no Araucarian speci- 
mens having been found in the Potomac and no Sequoian speci- 
mens in the Trias. And generally the Araucarian type is more 
ancient. This evidence therefore points to a lower instead of a 
higher horizon. 

I have made a somewhat careful study of the specimens from 
the plant bed above Evans Quarry, and have asked Professor 
Knowlton to assist me, his experience in recently editing Les- 
quereux’s Flora of the Dakota Group having familiarized him 
with the forms of thatage. The result of our joint investigation 
may be summed up as follows : 

The specimens are few and fragmentary, and the only species 
that can be even approximately determined are: 

Asplenium Dicksonianum Heer. 
Quercus Wardiana Lx. ? 
Lindera venusta Lx. 

Avrallia, Tomei JLsx, & 

Virbunites Evansanus n. sp. 


262 THE JOURNAL OF GEOLOGY. 


The first of these was described by Heer from the Kome 
beds of Greenland (Gault or Urgonian), but it also occurs in the 
Atane beds, which are correlated with the Cenomanian and have 
been supposed to be nearly equivalent to the Dakota Group. It 
has been found in the Kootanie deposits of British America, in a 
supposed Neocomian deposit at Cape Lisbourne, Alaska, and in 
the Amboy Clays at Woodbridge, New Jersey. It is also one of 
the few ferns that have been found in the Dakota Group, where, 
however, it is rare. Its evidence, therefore, considered by itself, 
would be to put even this uppermost deposit in the Lower Cre- 
taceous, but this is overcome by that of the remaining forms. 
The specimens are the best in the collection, good and character- 
istic, leaving no doubt on the score of identity. 

Quercus Wardiana Lx., is an exclusively Dakota form, but the 
specimens are too imperfect to make the determination sure. 

Lindera venusta x., is a characteristic Dakota species, and 
one of the specimens leaves no doubt as to identity. 

Aralia Townert Lx., is also confined to the Dakota Group, but 
the specimens, though tolerably good, do not exactly agree, the 
lobes being too short. They most resemble the specimen figured 
by Lesquereux in his Flora of the Dakota Group, pl. xxxi, fig. 3, 
which he doubtfully refers to Sterculta Snow Lx., but which 
does not at all resemble the type specimens of that species, and 
probably belongs to Avaha Townert. 

The leaf which I name V2burnites Evansanus* is one of the 
best preserved in the collection, but it differs specifically from all 
the forms known to me. It is clearly of the type of Viburnites 
crassus Lx., and V. Masoni Lx., of the Dakota Group (FI. Dak. 
Gr., pp. 124, 125; pl. xlv), but is longer in proportion to its width 
with a larger number of secondary nerves, which are irregularly 
disposed, the angle differing on the two sides of the midrib, as 
do also their number and proximity. The branching is strictly 
dichotomous and the finer nervation is distinct. The margin is 
only preserved near the summit, but here it is that of V. crassus. 


t For Mr. Fred. Evans, proprietor of Evans Quarry, founder and leading citizen of 
Hot Springs, who greatly aided and facilitated the expedition. 


Wee CLIETACIZOWS TIME 1 TIEIE IIGACIS JEHILES, 20 


It thus appears that the flora of the beds above Evans Quarry 
is distinctly that of the Dakota Group, while all the plants found 
below that horizon as distinctly indicate a Lower Cretaceous age. 
The force of this evidence is to my mind irresistible, and it is 
safe to predict that if any other paleontological evidence is ever 
found it will confirm this conclusion. The question still remains 
as to where the dividing line is to be drawn. Between the cycad 
and fossil wood horizon and that of the Dakota leaves there are 
some hundred feet of sandstones and shales. Sixty to seventy- 
five feet of this consists of the massive or heavy-bedded building 
stone, which in places becomes flinty and very hard. As the 
thin shaly layer which separates this from the leaf bed may be 
safely put with the latter into the Dakota proper, and there seems 
no reason for separating the similarly constituted layer that inter- 
venes between the cycad horizon and the base of the sandstone 
from the one upon which it rests, the question is narrowed down 
to that of the position of the quarry sandstone. That question I 
will leave to the stratigraphical geologists. 

As to where in the Lower Cretaceous series the basal portion 
of the Cretaceous rim of the Black Hills should be located, it 
can only be said that the cycadean trunks elsewhere found in 
North America have all come from well down in that series or 
else from the Upper Trias. Leaving the latter cases out of the 
account we have the Maryland specimens and the one from 
Kansas. It was long supposed that the Maryland specimens 
were derived from the Iron Ore Clays, which were referred by 
McGee and Fontaine to an “ Upper Clay Member.” This is now 
known not to be the case, and it has been demonstrated that the 
cycads occur in the basal sands at the same horizon as the 
Sequoian trunks, and probably the same as the Rappahannock 
freestone, which has yielded more fossil plants than any other 
horizon. Whether this is the same horizon as that of the James 
river, where cycads and conifers prevail and no dicotyledonous 
leaves have been found, or a somewhat higher one, need not now 
be discussed, as the whole subject will soon be thoroughly pre- 
sented along with the evidence. Certain it is that the Potomac 


204 LEE JOULNALETORNGHOLOGNE 


cycads belong to the lower part of that formation. The Kansas 
specimen is confidently referred by Professor Cragin to the 
Trinity Group of the Comanche series of Hill, which forms the 
lowest division of that series. Professor Hill is disposed to 
accept this conclusion, and Professor Prosser of Washburn Col- 
lege, Topeka, sees no reason to doubt its accuracy. 

The other plants, as has been seen, occur about one hundred 
feet below the cycad bed. Professor Fontaine’s report above 
quoted places their significance in its true light and leaves little 
to add. The occurrence of Asplenium Dicksontanum shows simply 
that this common form persisted in the same area through a long 
period. But this it was already known to do. Should it, how- 
ever, prove to be the 7hyrsopteris rarinervis Font., it would be a 
characteristic lower Potomac species. 

The forms that Professor Fontaine refers to Glossozamites 
argue entirely for a Lower Cretaceous or even earlier age. Eight 
species of that genus are known, ranging from the Upper Trias 
to the Urgonian. Some are from the Lias, but most of them are 
found in the Wealden and Neocomian. They had a wide geo- 
graphical range, occurring in Greenland (Kome beds), India 
(Damuda series), and in various parts of Europe. One species, 
G. distans, is from the lower Potomac of Fredericksburg, Virginia. 

Gleichenia Zippei (Corda) Heer was first described by Corda, 
who referred it to Pecopteris, from the Gosau formation of 
Bohemia, supposed to be above the Cenomanian. It has since 
been found in the true Cenomanian of Bohemia and in the 
Quadersandstein of Germany. Heer found it in all the Cre- 
taceous beds of Greenland (Kome, Atane, Patoot), also in the 
Cretaceous of Spitzbergen. Newberry detected it in the Amboy 
Clays. It varies considerably, and the name may include more 
than one species. Fontaine compares the Black Hills specimens 
only with Heer’s Kome forms, and is not certain that they may 
not rather represent his own Aspidiam heterophyllum from the 
Lower Potomac of Fredericksburg. The evidence afforded by 
this species, therefore, is not strong, but it certainly does not 
occur in the Dakota Group elsewhere so far as known. 


THE CRETACEOUS RIM OF THE BLACK HILLS. 265 


Leaves of Pinus and Leptostrobus occur quite frequently in 
the Potomac formation in Virginia, Alabama and New Jersey, 
but have never been found in the Dakota Group. So far, there- 
fore, as these forms from the Black Hills go they favor the view 
that the bed in which they occur is Lower Cretaceous. 

The chief argument from the plants is that they were all of 
humble types, no dicotyledonous leaves occurring among them. 
The force of this argument may be appreciated when it is remem- 
bered that the flora of the Dakota Group, one of the richest fos- 
sil floras of the world, consists, as now published, of 460 species, 
of which 429 are Dicotyledons. There are only 6 ferns, 12 
cycads, 15 conifers and 8 monocotyledons. The cycads are only 
known by fragments of fronds or pinnae, and a few doubtful 
fruits. The chances are hundreds to one that any plant bed of 
that age will contain dicotyledonous leaves in profusion, and the 
lower forms very sparingly, if at all. This was found to be the 
case at the real Dakota plant bed above Evans Quarry. Only 
one fern was obtained, while leaves were abundant though diffi- 
cult to secure entire with the insufficient appliances with which 
we were provided. 

A closing word on the bearing of these facts upon the Lower 
Cretaceous of North America may be permitted. It would seem 
probable that a considerable portion of the deposits underlying 
the marine Cretaceous of the Rocky Mountain region which have 
heretofore been referred to the Dakota Group on purely strati- 
graphical evidence may really be much older. When in 1883 I 
descended the Missouri River from the mouth of Sun River to 
Bismarck, most of the way in a ‘‘mackinaw,” and in company 
with Dr. C. A. White, that able geologist was of the opinion 
that the rocks at the Great Falls of the Missouri belonged to the 
Dakota Group. They were seen distinctly passing under the 
Fort Benton shales below, and there were no more indications of 
a division line at any point in the series than Professor Newton 
found in the same section of the Black Hills. As no Cretaceous 
older than the Dakota Group was at that time supposed to exist 
in that region, it was natural to refer all below the Fort Benton to 


266 THE JOGKNAL OF GEOLOGY: 


that group. But when a rich plant bed was at length discovered 
at Great Falls it was found to belong to the Kootanie group of 
Dawson, as developed in regions nearly north of this point. 
Here then is another series in which the dividing line between 
the Upper and Lower Cretaceous has to be found. 

It would, perhaps, be rash to predict that like conditions will 
be found to prevail at most points along the slopes of the Rocky 
Mountains, but the facts are sufficient to constitute a good work- 
ing hypothesis, and a systematic search at various points in the 
rocks that overlie the Red Beds and the Jurassic wherever these 
occur may result in further valuable discoveries. One additional 
fact that points in this direction may be noted. There was 
picked up on the surface within the Laramie terrane at Golden, 
Colorado, a segment of a small cycadean trunk which Lesquereux 
called Zamiostrobus mirabilis, but which has been sent to Count 
Solms-Laubach, Professor of Botany at the University of Stras- 
burg, and the leading authority on the subject, and pronounced 
by him to be a trunk and not a cone (as, indeed I had myself 
previously stated),’ referable to the genus Cycadeoidea. This 
region, as most geologists know, lies at the foot of the Front 
Range, and marine Cretaceous passes under the Laramie at 
Golden. The several members of the Cretaceous, in descending 
order, would naturally be found in passing up the adjacent slope, 
and if a horizon yielding cycad trunks occurs here it would be 
very natural that some of these cylindrical trunks should roll 
down the steep escarpment and be arrested on the plain below 
where this specimen was found. This explanation is far more 
probable than that this form could have grown in Laramie time, 
though no one can say that this is impossible, especially as the 
specimen is a diminutive one and may represent the degenerate 
descendants of the robust forms of the Lower Cretaceous. 

Whatever future consequences may grow out of the discov- 
eries recorded in this paper they at least, in and of themselves, 
constitute a fresh contribution to our rapidly growing knowledge 
of one of the hitherto least known periods of North American 


geology, to wit, the Lower Cretaceous. 
LESTER F. Warp. 
™Science, Vol. IIL., p. 533 (1884). 


ON DIPLOGRAPTIDA, Larwortu.? 


In the fall of 1888, H. Munthe brought from Bornholm a 
piece of Baltic sea limestone? [Ostseekalk | with graptolites, 
which he kindly gave me, as I was at work on the Silurian region 
of the Bothnian sea. From this piece, half the size of one’s fist, 
I have obtained, by the aid of muriatic acid and vinegar, several 
hundred pieces of a Diflograptus. As this compact limestone is 
excellently qualified to preserve the very finest details, the frag- 
ments, which consist mainly of proximal-ends and sciculz, fur- 
nish excellent material for the examination of the inner organi- 
zation of this particular Diplograptus. 

These remains are of a half-carbonized, chitinous substance, 
and after separation were dark brown and almost opaque, there- 
fore I treated them with Schulze’s maceration medium by which 
their color was changed to light brown or yellow. After care- 
ful washing with water, they were further treated with alcohol 
and oil of cloves, and were then preserved in the ordinary way 
in Canada balsam. 

According to the present acceptation, as recorded in general 
hand-books of paleontology,? and in the main the same as that 
given by Lapworth‘ as early as 1873, the family Diplograptide, 
Lapw., is characterized as follows: Hydrozoma, consisting of 
two branches united dorsally, between which the scicula is 
imbedded, its broadest portion forming the proximal end of the 
hydrozoma. 


«Extract from Bulletin of the Geological Institute of Upsala, Vol. I, No. 2, 1893. 
Translated from the German by CHARLES SCHUCHERT. 

2C.WIMAN: Ueber das Silurgebiet des Bottnischen Meeres, I, p. 73, Bull. Geol. 
Instit., of Upsala, Vol. I, No. 1, 1893. 

~3K. A. ZiTTEL: Handbuch der Palzontologie, Abtheilung I, Band I, 1876-1880. 

H. A. NIcHoLson and R. LyDEKKER: A Manual of Paleontology for the use of 
students, Part I, Third Edition, 1889. 

4Notes on British Graptolites and their Allies, I—On an improved Classification 
of the Rhabdopora, Parts I and II, Geol. Mag., Vol. X, pp. 500, 555, 1873. 

267 


268 THE fOOKNAL OL’ GH OLOGY. 


Since in fact the graptolites are generally compressed and 
altered into a metallic sulphide, or are otherwise poorly pre- 
served, and as this was also largely the case with the material 
examined by Lapworth, the genus Diflograptus was referred to 
the Dipriomde, mainly by a comparison with other forms, partic- 
ularly Didymograptus and Dicranograptus. 

In 1876, Lapworth’ described two species of a new genus, 
Dimorphograptus, and, because of these, doubted the existence of 
any diprionidian forms. ‘ The proper view, he believed, was that 
the scicula in all graptolites develops but one bud. This view (an 
opinion founded on fact) that a monoprionidian scicula which at 
first gives off a monograptus-like hydrosoma could really give 
origin to a complete diplograptus-like distal end, has in later 
literature never been considered, but the older idea has been 
persistently retained to the present time. . 


The Scicula. In the present material, this is represented by 
168 specimens, and of these 85 are separate. The form of the 
scicula is given in Pl. II., fig. 1-5 and 7-9. It is divisible into 
two essentially different parts, the distal one having a very thin 
and transparent wall, while the proximal is thicker and less 
transparent. Along the wall of the distal part are longitudinal 
thickenings or lines which branch and anastomose basally, and , 
are lost near the boundary with the proximal portion. They 
unite, however, in the point of the scicula, and form the distal 
portion of the virgula to which I will again refer. Between the 
two parts of the scicula there is no septum. 

In the proximal part of the scicula can be seen closely 
arranged diagonal lines, which I regard as growth lines. These 
have the same appearance as the often described thecal lines, 
_ differing only in the fact, that at a certain distance from the vir- 
gula, they gradually bend downward to join it at a sharp angle. 
In the very oldest part of the proximal portion of the scicula, the 
lines round regularly (Pl. II., fig. 1), since the virgula, when these 
were forming, was not yet present. Very soon, however, they 
begin to exhibit a slight downward bending, and this increases 

On Scottish Monograptide. Geol. Mag., Decade II, Vol. III, p. 544, 1876. 


ON DIPLOGRAPTIDA, LAPWORTH. 269 


line for line until the virgula begins to show, and practically 
absorbs the lines. The angle at which the lines and the virgula 
unite diminishes with age. The mature scicula is provided with 
three spines at its aperture, one of which is the cylindrical vir- 
gula. The other two are flat, and should probably be termed 
lobes. They have that appearance, as shown in figure 5, and 
are situated opposite the virgula on each side of a shallow emar- 
gination of the aperture, joined by a slight swelling of the border 
of the indentation. 

The form and completion of the aperture gives the scicula 
a particularly conspicuous -bilateral symmetry, on account of 
which the animal at this stage recalls a bryozoan rather than a 
modern hydroid polyp. 

The Theca. Before the scicula has matured, there forms, at the 
point illustrated in Pl. II., fig. 4, the beginning of a second tube, 
which is also provided with growth lines. The circular perfora- 
tion by which it communicates with the cavity of the scicula has 
been observed in forty-one examples. This opening is not pro- 
duced by absorption of the wall as shown by the slight irregu- 
larity of the scicular growth lines at the origin of the second 
tube (PI. II., fig. 4). This tube does not develop into a general 
canal or similar part, but forms the first theca. Then from this 
one chamber of habitation there simply develops a second. 

The first theca (PI. II., figs. 4, 5) at once leans closely on the 
scicula, widens very rapidly, approaches toward the virgula, and 
in bending around the scicula passes it, so that the theca comes to 
lie on the back (dorsal) side* of the scicula, and eventually both 
increase at an equal rate towards the proximal end. The growth 
lines of the first theca like those of the scicula, although ina 
less degree, are also drawn along, so to speak, by the virgula. 
As soon as the theca, which clings closely to the virgula, has 
grown a little further than the scicula towards the proximal end, 
it again changes its direction, and bends outward and eventually 
upwards. Where it begins to grow upwards, it gives off from 
one to three spines in succession, which start with a slight emar- 


*] have named that side the front which in figures 4 and 7, faces the observer. 


270 THE JOURNAL OF GEOLOGY. 


gination of the wall, and appear to develop like the spines of 
mollusks. In one example (Pl. II., fig. 6), two approximate 
spines are joined by a thin skin. Therefore there are from four 
to six spines on the proximal end of this Dzplograptus. 

A second large hole opens on the first theca towards the front 
side (Pl Il), fig: 4), On the back side (PIF Il) fig. 5) the lines 
are disposed parallel with its margin; on the front, however, 
they converge. From this opening comes the second theca 
(PI. II., fig. 7), on the right side in front ot the scicula. Shortly 
after it has left the first theca, the turning of the hydrosoma 
must have taken place; 7. ¢., both thece now begin to grow in 
an opposite direction and thereby change the direction of the — 
aperture towards the distal end. Further scicula growth probably 
ceases at this stage of development. The newly-formed theca 
fastens itself to the forward spine on the right side of the scicula. 

The second theca hardly has left the first when it gives ort- 
gin to the third, which also lies on the first, and is therefore 
situated on the left side. The pore uniting the third theca with 
the second is situated a little more proximally than that which 
joins the second with the first. The earliest budding of the third 
theca, therefore, occurs between the origin of the second and 
the turning of the hydrosoma. Its lower part fills the space in 
the bend of the first theca (PI. II., fig. 8). 

In my material occur many specimens having only the scic- 
ula, the first two thecz, and the proximal portion ‘of the third. 
If such an example were pressed flat without relief, and changed 
into pyrite, it would be recognized as a scicula having two buds 
with a common canal. The third theca increases only at the dis- 
tal end. From it, the fourth theca takes its origin, and is situ- 
ated in front of the scicula on the right side of the hydrosoma 
(Cele 1G, lee 3). 

Even if the openings between the first and second and the 
second and third thecze were not apparent, but only the origin 
of the first theca from the scicula and the fourth from the third 
were observed, the following law for the formation of the thece 
could be deduced: Each theca has its origin in the next on the 


ON DIPLOGRAPTIDZ, LAPWORTAH. 271 


opposite side of the hydrosoma. The alternating of the theca, 
therefore, is not only governed by the greater space attainable, 
but by the age and origin of the thece as well. In certain 
respects this law is also true for the scicula which may be 
regarded, if desirable, as the primary theca. 

The growth lines meet on the outer edge of the hydrosoma in 
such a way as to produce a zig-zag line (Pl. IL, fig.7). This is 
probably produced by the same cause as the marking of the lobes 
ofthe scicula. Analogous to these, also, are the well-known paired 
spines of the thecal apertures of certain diplograptids, which are 
likewise an expression of the bilateral symmetry of the thece. 

The partition wall between two adjoining or opposite thecz 
is naturally double, and exhibits a slight thickening on the prox- 
imal inner edge. 

The angle between the median line of the hydrosoma and the 
double partitions of the thece is greater in the distal portion, 
(25°-30°) than in the proximal, where it is occasionally zero. 

An examination of figures 8 and 9 shows that the scicula 
originally lies outside of the hydrosoma, except for the loose 
adherence of the thece, being united to it only at the termina- 
tion of the first theca. Nevertheless the earliest thece are 
indented on the dorsal side and partly enclosing the scicula, so 
that it appears to lie in a depression of the outside of the hydro- 
soma. The thecze extend more and more over the scicula until 
the central space is nearly transformed into a tube encircling the 
scicula, and when the fifth theca, z. ¢., the third on the same side 
as the first, finally opens, the scicula then disappears into the 
hydrosoma (PI. II., fig.g). The place where the scicula comes in 
contact with the perforated wall of the hydrosoma lies beneath 
the boundary between the two parts of the scicula (Pl. II., fig. 9). 

The Virgula. As the virgula has been observed to occur 
within, and protrude from, both ends of the hydrosoma, it has 
been naturally concluded that the virgula passed without inter- 
ruption through the entire hydrosoma. This, however, is not 
the case (Pl. II., figs. 1-3). The origin of that portion of the 
virgula which lies in the left wall of the proximal part of the 


27:2 THE JOURNAL OF GEOLOGY. 


scicula has been already described. This part like the scicula 
grows towards the proximal end. The distal portion of the 
virgula does not begin to develop until the scicula has been 
taken into the hydrosoma. It is likewise stouter the further it is 
removed from the point of the scicula. As it has its origin in 
the union of the longitudinal lines of the distal portion of the 
scicula, it appears very probable that the entire distal part of the 
scicula, also, first had its inception when the scicula is taken into 
the hydrosoma. Accordingly, the scicula, when it was yet free, 
would have been either open on the distal end or it had a very 
thin wall which disappeared later. The first shell-layer, there- 
fore, was a small simple ring. 

Here and there, quite irregularly, the virgula fastens itself to 
the above-mentioned swellings on the proximal ends of the thecal 
partitions (Pie mgs ii 12)).) winetigine solic mismentinelhyannecs 
In diagnoses of diplograptids, it is often mentioned that the vir- 
gula extends beyond the distal end. This need not be accidental 
in a species of this nature, since in forms where the virgula is not 
fastened to the diagonal swellings, it has a greater chance of 
being preserved, even if the periderm is broken away. If the 
virgula is regularly attached to every partition, it can only 
become protruding under very favorable circumstances. In this 
species, I did not see the virgula protruding. 

A common canal as progenitor for all theca does not exist. 
The partition walls between the theca, moreover, join so closely 
on the center of the hydrosoma that the virgula hardly has suf- 
ficient space to straighten itself. 

A longitudinal septum is not present. 

In summing up the results of my investigations, the follow- 
ing points are shown : 

1. The scicula consists of two parts, is basally open, and 
bilaterally symmetrical. . 

2. From the scicula there sprouts but ove bud. This Dzplo- 
graptus is therefore monoprionidian. 

3. This bud does not develop into a canal, but into a theca. 

4. Each theca comes forth from the next more proximally 


ON POZO GIA EMMY AE VGA PMV ORIEL: 273 


situated theca of the opposite side, and not from a common 
canal. 

5. The hydrozoma including the virgula has grown in two 
opposite directions. 

6. The scicula is not imbedded between two branches grown 
together, but is free originally, and later is incorporated within 
the periderm. 

7. The virgula is not double, and has two quite distinct 
phases of development. 

8. To the virgula are occasionally attached the bases of the 
thecal partitions. 

g. A common canal as progenitor of the thece does not exist. 

10. A double longitudinal septum is not present. 

It is not now my intention to assert that this organization is 
repeated in all the representatives of the family Diplograptide, 
for so little of their internal structure is yet known, they may 
have a collection of remotely related forms with thece arranged 
in two rows, but since this family is entirely or in the maina 
natural one, the deviation from the general plan of structure 
cannot be very great. 

Hight days after I had announced the above before the geo- 
logical section of the Student’s Natural History Society, and 
after I had nearly finished writing it, I received from S. L. Torn- 
quist a copy of his work “Observations on the structure of some 
Diprionde.”’ Sartryck af Kongl. Fysiografiska Salls Kapets 
Handlingar. Ny foljd 1892-3, Bd. 4, Lund, 1893. Lund Univ. 
Arsskrift, tom XXIX. 

The ‘connecting canal,’ which, according to Tornquist, 
unites the scicula with the ‘‘common cavity of the rhabdosoma,”’ 
is that part of the first theca which grows downwards. The 
proximal end of Chmacograptus scalaris, Lin., figs. 7-15, and 
18-20, C. internexus, Tqt., fig. 25, Diplograptus palmeus, Barr., 
figs, 29, 33-35, and Cephalograptus cometa, Gein., figs. 39-41, 
show the identical structure which I have just described. The 
groove illustrated in figure 17 and mentioned on page 6 as ‘‘a 
narrow longitudinal groove as to the nature of which I am not 


274 THE JOURNAL OF \GEROLO GY. 


5) 


able as yet to offer any satisfactory explanation,” can be, since it 


terminates before it reaches the point of the scicula, nothing else 
than that portion of the virgula which lies in the wall of the 


scicula. 

Tornquist nowhere says that the described species are mono- 
prionidian, but this can be clearly seen in the figures 39-41 of 
Cephalograptus cometa, Gein., and if those just cited are compared 
with my own, there can be no doubt that the species above men- 
tioned are also monoprionidian. 

It is particularly interesting to note that the presence of a 
longitudinal septum does not depend on the diprionidian charac- 
ter of the Diplograptide as generally accepted. 


EXPLANATION OF PLATE. 


The figures have been drawn about twice the size of the scale, with Zeiss 
and Abbe’s drawing apparatus. The shading was obtained by still greater 
enlargement, and by various accessories to the microscope. The given scale 
does not apply to figure Io. 

Fig. 1. Young scicula; dorsal side. X 37. 

Figs. 2-3. Adult scicula; front view. The thecz are removed. 37-1. 

Fig. 4. Form and place of the first theca and the perforation from which 
the second will come; front view. X 37. 

Fig. 5. The same; dorsal view. X 37. 

Fig. 6. The first theca with three spines, two of which are united by a 
thingskinge ea. ; 

oes 7 Form and position of the second and third thece ; front view. X 37. 

Fig. 8. Form and position of the fourth theca and imbedded scicula. X 37. 

Fig. 9. Incorporation of the scicula in the hydrosoma. X 37. 

Fig. 10. Distal portion. The transparency partially made use of. The 
virgula is wholly free. X 13. 

Figs. 11-12. Attachment of the proximal edges of the partitions to the 
virgula. X 37. 

The material is in the collection of the Geological Institute at Upsala. 

CarL WIMAN. 


oh Ieee) IU 


JOUR. GEOL. VOL. I1., 1094. 


yes Se ett 


i 


eas D 


GEOLOGICAL SURVEYS IN ALABAMA. 


Furst Survey. 

Upon the appointment of Professor Michael Tuomey, in 1847, 
to the professorship of Geology in the University of Alabama, 
it was made a part of his duty to spend such portions of his 
time, not exceeding four months in each year, in exploring the 
state in connection with his proper department, as the Trustees 
might consider for the advantage of the state. Professor 
Tuomey, in accordance with these instructions, began imme- 
diately his explorations, and thus the first systematic examina- 
tion of the geology of Alabama was instituted. Such extracts 
from his reports to the Trustees upon this work as were con- 
sidered of general interest, were published from time to time in 
the newspapers of the city of Tuscaloosa, and in January, 1848, 
the state legislature made recognition of this effort by appoint- 
ing Professor Tuomey State Geologist, and requesting him to 
lay before them the results of his explorations, to be published 
by the state. Thus was begun the first geological survey of 
Alabama. From 1848 to 1853 Professor Tuomey continued 
these explorations at the expense of the University of Alabama, 
the state having made no appropriation tor the purpose, and in 
1849 he presented to the legislature his first biennial report, 
which was published in 1850 by the state. The geological map 
was not ready, however, for distribution with the report, and 
appeared separately. When we consider the great number of 
observations recorded in this volume, and the accuracy with 
which the limits of the various geological formations were laid 
down upon the map, after only two years’ exploration, in a state 
about whose geology almost nothing was previously known, we 
cannot fail to recognize the genius of the man. 

In 1854 the legislature passed a law appropriating $10,000 
for the support of the Geological Survey, and an additional sum 

275 


276 THE JOURNAL OF GEOLOGY. 


of $2,500 per annum for the salary of the state geologist. Under 
this law Professor Tuomey was appointed State Geologist by 
Governor Winston, resigned his position in the University, and 
devoted his whole time to the survey till about 1856. During 
the two years, however, of his service to the state he still kept 
his office at the University of Alabama, and delivered lectures to 
some of the classes of that institution. During this time he was 
assisted by Professor E. Q. Thornton, O. M. Lieber and others, 
and in 1855 Professor John W. Mallet was appointed Chemist 
to the survey. The results of the labors of Professor Tuomey 
and his assistants were brought together by him in a report which 
was submitted to the legislature in November, 1855, but, by the 
negligence of the state printers, and for other reasons, the pub- 
lication of this report was delayed for more than two years. 
The appropriation for the survey being exhausted, Professor 
Tuomey resumed his work at the University in 1856, intending 
to devote his leisure time as before to the survey, and especially 
to the elaboration of his notes. The summer of 1856 was 
devoted to field work, but his death occurred the following year 
1857, on March 30. 

Upon the death of Professor Tomy Dr. Mallet undertook 
the task of editing and bringing out the long delayed report 
It was found that part of the manuscript had been lost, some of 
it was incomplete, and thus a large amount of valuable material 
was lost to the state and to science. In September, 1858, this 
Second Biennial Report at last appeared, accompanied by another 
map of the state, more detailed than the first. After the death 
of Professor Tuomey, in 1857, the survey was discontinued. 


From 1868 to 1876 a Commissioner of Industrial Resources 
was one of the regular officers of the state government, and four 
small pamphlets were issued from that office, but the Legislature 
of 1874-5 practically abolished the office by making no appro- 
priation for the salaries of the Commissioner and his Assistant, 
and in the code of 1876 no provision was made for the continu- 
ance of the Bureau. 


GEOLOGICAL SURVEYS IN ALABAMA. Bay 


Second Survey. 

Furst Decade.—In the meantime, upon the reorganization of 
the University of Alabama, in 1871, after a “reconstruction” 
régime of five years, the Board of Regents of that institution 
again took the initiative in re-establishing the Survey by requir- 
ing the Professor of Geology to devote as much time in traveling 
over the state, in making examinations and collections in geology, 
as would be consistent with his duties at the University. 

In pursuance of this ordinance, the present writer, who at 
that time filled the chair above mentioned in the University, 
spent a part of his vacation in 1871, at his own expense, in the 
examination of certain marine Tertiary deposits in Clarke, Wash- 
ington and Choctaw counties. 

The subject of the Geological Survey was brought before the 
legislature of 1872-3, and an act was passed by them in 1873, 
reviving the survey, naming Eugene A. Smith, State Geologist, 
and making an appropriation of $500 per annum for the expenses 
of the survey, and an additional appropriation of $3,000 for an 
outfit for chemical laboratory, and traveling and camp equip- 
ments. In 1877 a bill was passed making a biennial appropria- 
tion of $200 for the purpose of preparing maps and other illus- 
trations for the geological reports. Another special appropriation 
of $250 was made in 1879 for the same purpose. 

During the ten years from 1873 to 1882 inclusive, the writer 
devoted the greater part of the three months of each summer 
vacation to geological excursions, receiving no compensation 
therefor in the way of salary. The actual traveling expenses were, 
however, defrayed out of the annual appropriation of $500, 
which also paid the other contingent expenses of the survey. In 
the summer of 1878 Mr. Henry McCalley, at his own expense, 
accompanied the writer in the field, and during the following 
years, from 1879 to 1882, he undertook independent field work, 
without compensation from the survey beyond the payment of 
his expenses while in the field. At this time he held the position 
of Assistant in the Chemical Department of the University, then 
also under the charge of the present writer. There were other 


278 THE JOURNAL OF GEOLOGY. 


volunteer assistants during this time; the two whose contribu- 
tions are to be found in the survey reports being Professor W. C. 
Stubbs, who made a number of chemical analyses, besides taking 
part in the field work, and Mr. T. H. Aldrich, who prepared a 
valuable sketch of the early history of coal mining operations 
in Alabama, published in the report for 1875. Pi 
Publications. —During this period of ten years there were pub- 
lished four annual reports, viz., for 1873, 1874, 1875, and 1876, 
and three biennial reports, viz., for 1877-8, 1879-80, and 1881-2. 
With the exception of the Agricultural report of 1881-2, these 
were of the nature of preliminary or reconnoissance reports, and 
they deal chiefly with the economic features of the state. The 
report for 1873 was a mere statement of the plan of the work 
proposed. That of 1874 is concerned with the crystalline region, 
and particularly with the copper-bearing strata. At the time 
when the examinations were made there, the whole section was 
greatly interested in the subject of copper, just as now it is 
interested in gold. A part of the next report, 1875, treated of 
the same subject, but the greater part of it was devoted to the 
examination and classification of the Valley formations, of Jones’ 
Valley and the great Coosa Valley region. Professor Tuomey 
recognized the occurrence in these valleys of the Silurian, Dev- 
onian, and Subcarboniferous formations, without undertaking the 
subdivision of the same, except in the case of the Clinton and 
Trenton. During the summer of 1875, it was possible for the 
writer to establish the practical identity of these formations with 
what had already been so clearly described for Tennessee by 
Professor Safford, and he established the fact of the existence in 
Alabama of the Ocoee, Chilhowee, Knox Sandstone, Shale and 
Dolomite, the Lower and Upper Subcarboniferous with their 
respective minor divisions. The report for 1875 contained also 
the sketch of the early history of Coal Mining in Alabama, to 
which reference has already been made above, and there were 
also presented the records of the borings by diamond drill in the 
different parts of the Warrior Field together with an attempt at 
correlating the same. The report holds also many details of the 


GEOLOGICAL SURVEYS [N ALABAMA. 279 


occurrence and composition of iron ores and limestones of this 
district. The report for 1876 continued the examination of the 
valley regions, and contained a paper on the Alabama fresh water 
shelis by Dr. James Lewis, contributed by Mr. Aldrich. 

In 1877-8 attention was turned to the Warrior Coal Field, till 
then comparatively unknown, and maps were published of Walker, 
Fayette, Marion, and Winston counties, which were practically 
underlaid with Coal Measures. Notwithstanding the fact that no 
coal was mined at that time in all this region, and it was not 
possible with the means at the disposal of the survey to open 
the seams so as to show their true value, the publication, espec- 
ially of these maps, turned the attention of investors to these 
counties, and the next few years witnessed marvellous develop- 
ments there. 

In 1878-9 a movement was set on foot to secure an appro- 
priation from Congress for the purpose of making navigable the 
Upper Warrior river to develop the coal seams along its course, 
and the writer, with Mr. McCalley and Mr. Jos. Squire, ran a line 
of levels from the forks-of the Warrior down to Tuscaloosa, and 
made special re-examination of the coal seams within available 
distance from the river. The expense of this survey was borne 
chiefly by the War Department, but the map and report were 
published by the survey. In this document the details of the 
coal seams were given with a much greater degree of fullness 
than heretofore, together with many facts bearing upon their 
stratigraphical relations. In this volume was also a continuation 
by Mr. McCalley of the description of the Tennessee valley, 
begun the year before by Mr. McCalley and myself; together 
with the analyses of some 50 specimens of coal from the Warrior 
field. 

In 1880 the writer was requested by Dr. Hilgard to prepare 
for the Tenth Census a report on Cotton Culture in Alabama 
and Florida, and in 1883 was published the state report, embrac- 
ing the results of these observations in Alabama. In addition to 
the special descriptive matter, this report contains a general dis- 
cussion of the composition, mode of formation, and properties of 


280 THE JOURNAL OF GEOLOGY. 


soils and of the changes produced by cultivation. The maps 
showing the agricultural divisions of the state, and showing the 
relations between the area cultivated in cotton and the total area, 
were prepared for the Tenth Census, but the survey had the 
privilege of using the plates. The other illustrations were pre- 
pared by the survey. This report deals in some detail with the 
agricultural divisions of the state, and contains many analyses of 
soils and marls, made partly by the Census and partly by the 
geological survey. 

In the case of the two reports last named, advantage was 
taken of opportunities in which work done by the writer for 
other organizations could be turned to the direct benefit of the 
survey, thus securing much fuller reports and better illustrations 
than would have been at all possible with the survey funds alone. 

Cost.—The printing of these reports was paid for out of the 
general printing fund of the state, at a cost of $6,750, and this, 
added to the $8,000 directly appropriated to the survey for 
equipment, field work, and all other purposes, gives $14,750 as 
the total cost of the survey during these ten years; an average 
of $1,475 per annum. 


Before going further it may be well to consider what was 
accomplished during this decade, to point out the advantages 
derived from this long period of preliminary work, and to call 
attention to some of its manifest disadvantages. 

1) Every county in the state was visited, and the main fea- 
tures of the geology and resources of each were ascertained ; 
descriptions were published of each of these counties, in some 
cases giving much detail; the main subdivisions of the geolog- 
ical formations in the state were established ; the mode of occur- 
rence and general distribution of the most important mineral 
resources were described and illustrated by many analyses; and 
the agricultural features of the entire state were given with an 
approach to completeness, thanks to the coéperation of the Tenth 
Census. 

2) The experience and the knowledge of the territory acquired 


GEOLOGICAL SURVEYS IN ALABAMA. 281 


by the state geologist during this long period, have unquestion- 
ably since been of benefit to the state, for without such exper- 
ience on his part the disbursing of large sums and the directing 
of the work of the enlarged survey, so as to secure the best 
results and to avoid injudicious expenditures, would have been 
attended with many perhaps insurmountable difficulties. I might 
add further that the cost to the state of this preliminary work, 
as shown above, was small. - 

3) On the other hand, while at the beginning of the work 
these preliminary reports supplied in a measure the information 
then demanded, it cannot be denied that the progress of the state 
in the development of its great resources, especially in the lather 
part of this period created a demand for much more detailed and 
special information in certain directions than the survey could 
supply without some greater expenditure of money. 


Second Decade-—Accordingly, a bill was brought before the 
General Assembly of 1882-83, providing for an annual appropria- 
tion of $5,000 for the ensuing ten years, and this bill became a 
law in February, 1883. Before the expiration of this ten-year 
limit the amount of the annual appropriation was increased in 
1891 to $7,500; to continue till otherwise ordered by the General 
Assembly, thus avoiding the necessity of renewed legislation at 
every meeting. Under these laws assistants were appointed and 
work assigned as follows. Henry McCalley, in the Warrior Coal 
Field and subsequently in the Valley regions; Jos. Squire, in the 
Cahaba Coal Field; A. M. Gibson, in Murphree’s Valley and the 
Coal Measures adjacent thereto, and afterwards in the Coosa Coal 
Field; the State Geologist, with D. W. Langdon, @ Be Aldrich, 
and L.C. Johnson, undertook the examination of the Cretaceous 
and Tertiary formations of the Coastal Plain. Administrative 
work, the editing of reports, and the preparation of the Geolog- 
ical Map, have however engrossed a great part of his time. aber, 
Dr. George Little made an examination of the clays of the Lower 
Cretaceous; Dr. W. B. Phillips began the investigation of the 
Gold region, and Mr. K. M. Cunningham has demonstrated 


282 THE JOURNAL OF GEOLOGY. 


the existence of true chalk deposits in our Cretaceous forma- 
tion. 

Geological Reports published or in preparation Departing from 
the strict chronological order we shall state briefly the work 
accomplished and in hand in each of these divisions. 

In 1886 was published McCalley’s Report on the Warrior Coal 
Field, containing detailed sections of all the exposures of coal 
seams in the basin division of this field, together with Mr. Gib- 
son’s account of part of the plateau division. This report also 
contains the first approximately full columnar section of the meas- 
ures of this field. In 1891 appeared McCalley’s report on the 
Plateau region of the Warrior Field with map and colored sec- 
tions. Mr. Gibson also contributed to this volume. 

Active work has also for the past three years been going on 
and is still in progress under Mr. McCalley’s direction in the 
Warrior Basin, in locating accurately the surface outcrops of the 
important coal seams. His examination of the Valley regions 
and their economic products, including iron ores, limestones, 
building stones, and bauxites, has been in progress for the past 
five or six years, and his report thereon is in great part written up. 

In 1890 was published Mr. Squire’s Report and Map of the 
Cahaba Coal Field. This document is the outcome of about thirty 
years’work, during which time Mr. Squire has been continuously 
engaged in this field either in active mining or in making instru- 
mental surveys for individuals or corporations, all the results of 
which have been incorporated in his report. The map shows accu- 
rately the surface outcrops of all the important seams of coal, and 
a number of carefully constructed vertical and horizontal sections 
of the field. It exhibits also the geology of the adjacent valleys, 
compiled mainly from Mr. McCalley’s notes by the present writer, 
who has also added a description of these formations and a sketch 
of their accumulation and subsequent history. 

In 1884 the existence of phosphatic nodules and marls was 
discovered. The distribution, quality, and quantity of these mate- 
rials were pretty thoroughly investigated by Mr. Langdon and 
myself, to form part of the coastal plain report; but the holding 


GEOLOGICAL SURVEYS IN ALABAMA. 283 


back of this report for the map, and on account of active work in 
progress in the lower part of the state which it was desirable 
to incorporate therein, led us to issue in 1892, as Bulletin No. 2, 
an account of these marls in separate form. 

In 1893 appeared Mr. Gibson’s report on the Geology and 
Resources of Murphree’s Valley, the publication of which had 
been delayed on account of the lack of a suitable map for its 
illustration. His report on the Coal Measures of Blount Moun- 
tain has just been published, 1894, and he is at work upon a pre- 
liminary report on the Coosa Coal Field. 

Dr. Wm. B. Phillips, in 1891, undertook the examination of 
the gold region, spent part of one summer in the field work, and 
prepared a partial report thereon, but was unable to complete 
this work, and it was taken up in 1893 by myself and Mr. W. M. 
Brewer. It has been conclusively shown that these fields, with 
suitable methods of extracting the gold, can be worked in many 
places at a profit. The great activity now prevailing there leads 
us to think that the mining of gold will soon take an important 
place among the industries of the state. 


Cooperation of the U. S. Geological Survey. Soon after the con- 
solidation of the United States Geological Surveys into one organ- 
ization in 1879, propositions were made by the director for codp- 
eration with the state surveys, in accordance with which it was 
agreed that the U. S. Survey should make in Alabama accurately 
measured sections of our Paleozoic formations at two points 
selected after full consultation. This plan was afterwards slightly 
modified, and the results were published in 1892 as Bulletin No. 
4 of the State Survey, a Report on the Geology of Northeast- 
ern Alabama and the adjacent parts of Georgia, by C. W. Hayes. 
This region in Alabama had already been pretty closely examined 
by the state survey, so that the change in the original plan caused 
some degree of duplication of work, but the mode of treatment 
of the subject and the map showing the connection with Georgia 
make this an exceedingly acceptable contribution. 

Another result of this coéperation was a trip in 1883 down 


284 THE JOURNAL OF GEOLOGY. 


the Warrior and up the Alabama rivers, made by L. C. Johnson 
and myself at the joint expense of the State and National Sur- 
veys, during which we collected the data for the first attempt at 
the stratigraphy of the Cretaceous and Tertiary formations of our 
Coastal Plain. The greater part, however, of the material after- 
wards brought together by the writer and published as Bulletin 
No. 43 of the U. S. Survey was collected in the following seasons, 
1884—5—-6, by the Alabama survey alone, by Messrs. Langdon, 
Aldrich and myself. Mr. Langdon afterwards carried these exam- 
inations across the state to the Georgia line, and thence down the 
Chattahoochee to Bristol, Fla., when he made the discoveries of 
the Chattahoochee and Alum Bluff series of Miocene formations, 
which have since become famous localities. 

Although the joint trip of the present writer and Mr. John- 
son, above mentioned, occupied only two weeks’ time, Mr. John- 
son was afterwards assigned by the U. S. Survey to independent 
work in this territory, especially in the examination of the post- 
Eocene formations, and it is to his work that we owe the greater 
part of our knowledge of the Grand Gulf and Pascagoula Mio- 
cene of this state. Mr. Johnson was also for one season in the 
employ of the state survey in completing the work thus begun. 
The present writer has also spent an additional season in this 
territory in 1891, and the coastal plain report above alluded to 
will contain the notes from all these sources. 

It was feared by many that the extension of the U.S. Survey 
into the territories of the older states would have the effect of 
preventing the organization of new state surveys, and of causing 
the discontinuance of those already in existence, but the con- 
tinuance or completion of existing surveys in New Jersey, Min- 
nesota, Illinois, Indiana, Pennsylvania, Kentucky, Alabama and 
Wisconsin, and the organization of new surveys in Texas, Arkan- 
sas, Missouri, Georgia, North Carolina and Iowa show that these 
fears have not been fully realized. The national and state sur- 
veys occupy practically somewhat different ground, and so far 
from being antagonistic, they should be mutually helpful. In 
the case of Alabama it may be asserted that the codperation of 


GEOLOGICAL SURVEYS IN ALABAMA. 285 


the U. S. Survey has been very distinctly advantageous. In 
retrospect one can, however, easily see how these benefits might 
have been materially increased by more frequent conferences and 
consequently more thorough mutual understandings and adjust- 
ments. 

Paleontology and Natural Fiistory—Wiith the small amount 
appropriated for the survey it would have been injudicious to 
use any of it on paleontology, but Mr. T. H. Aldrich contributed, 
without cost to the state, Bulletin No. 1, published in 1886, con- 
taining descriptions of new Tertiary fossils, with nine plates of 
illustrations. This is the first installment of what is designed to be 
a complete and illustrated account of our Tertiary paleontology. 

So also Professor Herrick, of Denison University, contributed 
a List of the Fresh Water and Marine Crustacea of Alabama, 
with Descriptions of New Species, which was published by the 
Survey in 1887, as Bulletin No. 1 of Vol. V. This paper, which 
also appeared as a Memoir of the Denison Scientific Association, 
is illustrated by eight plates of figures of the species described. 

From the beginning of the survey collections have been 
made by myself of the native plants of the state, and these col- 
lections, combined with those of Dr. Charles Mohr, of Mobile, 
were by him arranged and mounted, and the joint herbarium 
deposited in the cabinet of the University of Alabama. A pre- 
liminary list of the Alabama flora was printed in 1880, and Dr. 
Mohr is now engaged in preparing for the survey a report on 
the Botany of the state, in which every known indigenous 
phenogamous plant and fern will be listed, and full accounts 
given of the timber, forage, useful and noxious plants. The geo- 
graphical distribution of the Alabama flora and the mapping of 
the botanical provinces of the state will be a valuable feature of 
this report, which is now far advanced towards completion. 

In the progress of the work a new species of Croton of 
shrubby habit, C. Alabamensis, has been discovered, and many 
rare plants have been found growing upon our soil. 

Geological Map.—tLastly, the preparation of the geological 
map of the state has engrossed a large part of the time and 


286 THE JOURNAL OF, (GEOLOGY, 


attention of the state geologist for several years. The first 
difficulty to be overcome was the lack of a suitable base map. 
In this we had the aid of the U. S. Survey, in which office was 
compiled the first base map printed by the survey. As the work 
progressed numerous alterations and corrections became neces- 
sary, and not until 1893 was a satisfactory base map prepared. 
This map, on a scale of ten miles to the inch, with colors to show 
the geology; will be ready for distribution ina short time. It 
will be accompanied by a chart exhibiting the main lithological, 
economic, topographic and agricultural characters of each of the 
formations represented, and will embody the results obtained 
during the past twenty-one years. 

Cost—The cost of the survey during this period of eleven 
years, 1883-1893 inclusive, has been as follows: 


Eight annual appropriations of $5,000............--.-- $40,000.00 
hee annualeappropriatlons Ol M5 OOnm rn ete cr ence 22,500.00 
Printing, binding, illustrating, and distributing reports.. 13,347.00 


$75,847.00 


the entire cost averaging about $6,900 per annum. For the 
whole period of 21 years during which this survey has been 
active, the aggregate cost of the survey for all purposes has 
been $90,597, an average of $4,314 per annum. 

Economic results—Since the organization of the survey, the 
tax rate has been reduced over 50 per cent., without diminishing 
the revenues. The increase in the value of property in certain 
sections of the state that has rendered this possible, has been due 
in the main to the development of the mineral wealth of the 
state, and to this the survey publications have contributed a 
certain share, but how much it would of course be impossible to 
estimate. In this connection, however, it may be proper to say 
that some of the regions of the state in which the mining of coal 
and iron have since assumed vast proportions, were practically 
untouched by the pick of the miner, when our earlier reports 
directed attention by maps, analyses, and otherwise to their great 
resources : and very recently the survey has demonstrated the 


GEOLOGICAL SURVEYS IN ALABAMA. 287 


existence, within the Coal Measures, of certain areas heretofore 
untried, in which the mining of coal will undoubtedly be profit- 
able ; it has pointed out a source of wealth in the phosphatic 
marls of certain sections ; it has shown that gold may be mined 
with profit at many points within our limits ; it has demonstrated 
the fact that clays suitable for the manufacture of fine porcelain 
ware, fire-brick, tiles, and other articles, occur in practically 
limitless quantity in many sections ; it has pointed out the local- 
ities where good marbles and building stones may be had for the 
quarrying ; all these have as yet not been turned to account. 

Unsolved problems —Of the problems of geological interest, 
developed in the course of the survey but not yet settled, I may 
mention the following: The stratigraphic relations of some of 
our Lower Cambrian formations are still uncertain; the relations 
between the formations of unquestioned Cambrian age, and the 
gold-bearing semi-crystalline strata adjacent to them and in some 
instances interlocking, are yet to be definitely fixed ; the correla- 
_ tion of the seams of our three coal fields is still an unsolved 
problem, at least in its details. 

Work yet to be done.—After the issue of the publications now 
in hand, the most important items of work proposed, are i) Woe 
accurate mapping of the outcrops of all the coal seams of eco- 
nomic importance. The finishing of two or three of the sheets of 
the U.S. topographical survey will render this comparatively 
easy. 2) The preparation of county maps on the scale of half 
an inch to the mile, with accurate locations of all mineral 
deposits, mines, etc., as well as of the geological formations. 3) 
A republication, or rather a new edition, of the Agricultural 
report, with a map showing the distribution of the soil varieties. 
4) An investigation of the water supply of the Coastal plain 
region, with special reference to Artesian borings. Much of the 
material for this is already in hand and in part published. 

EUGENE ALLEN SMITH. 


INS0S, SUSUMU IAVE, PAVE INDIAN Que QUIS, IDJAAOSIIUS 


GENERAL FEATURES. 


Scope of the subject—The modern idea of ore deposits teaches 
that formations of this kind represent a process of concentration 
of mineral matter, either by chemical or physical means; in other 
words, that they are unusual localizations of certain minerals 
which are often found disseminated in smaller quantities in many 
common rocks, and that they differ from the same minerals situ- 
ated in other conditions, only in their degree of concentration. 
These concentrations may take place at different times in the 
history of the rocks in which the deposits occur. If they occur 
in sedimentary rocks, they may sometimes be formed during the 
deposition of the rocks with which they are associated, as in the 
cases of placer gold, stream tin, and sometimes of other ores; 


t The superficial alteration of ore deposits is a recognized principle of geology, in 
the same way as is the superficial alteration of any of the common rocks. Its impor- 
tance in some classes of ore deposits is also well understood, as in many precious 
metal deposits; while in other classes, its importance has been proved in, individual 
cases, as in the Lake Superior iron deposits. The causes and effects of superficial 
alteration in many classes of deposits, however, are not so generally understood, and 
it is the object of the present paper to show that such changes almost invariably give 
rise to exceedingly important chemicai and physical phenomena, while in many 
deposits, the question as to whether they can or cannot be profitably worked, depends 
largely on the extent and character of this alteration. 

The various treatises on ore deposits published in the United States and Europe 
make frequent mention of superficial alteration, but have not treated the subject 
fully. As early as 1854, however, before which time but little accurate informa- 
tion was had on the geologic nature of ore deposits, Professor J. D. Whitney in his 
classic volume, The Metallic Wealth of the United States, describes the alteration 
products, or gossans, in certain deposits and mentions others. On the more purely 
chemical side of the question, the work of Bischof, Daubrée, Roth, Rose, Hunt, 
Breithaupt, Blum, Julien, Deville, Debray, Volger, Moissan, Fremy, Lévy, Fouqué 
and others have afforded much valuable information and many useful suggestions. 
The chemical principles brought out by these various authors have been applied, to a 
certain extent, to the solution of the phenomena of the origin of ore deposits, but 
have not as yet been applied to anything like their possible extent to the solution of 
the phenomena of the alteration of ore deposits. 

288 


iO en Ol aes Deh MLON, OF ORE DEPOSTIM|S:. 289 


while if they occur in igneous rocks, they may sometimes be the 
result of concentration by differentiation from fused magmas.* 
More usually, however, ore deposits are a result of a concentra- 
tion after the formation of the enclosing rock, whether the latter 
be of sedimentary or of igneous origin. The mineral matter 
represented in this concentration may be derived from the enclos- 
ing rocks or closely adjacent rocks, as in the case of many, if 
not most, iron ore deposits; or it may be derived from more dis- 
tant sources, often from greater or less depths, as in some of the 
precious metal deposits. Occasionally, both these sources may 
be drawn on for mineral matter in one deposit. In this subject 
of the original source of an ore, we enter a field concerning which 
there has been much dispute of late years between the advocates 
of the lateral secretion theory and those who favor the idea of a 
deep-seated source for many ore deposits. It is not, however, 
the purpose of the present paper to enter into this discussion, 
and the following remarks are confined to what happens in the 
superficial parts of ore deposits, and to a less extent of allied 
formations, after the materials forming them have been brought 
into their present, or approximately their present, positions. 
Relation of alteration in ore deposits and in country rocks.—Ore 
deposits are generally more or less changed in their upper parts 
by atmospheric influences, so that very rarely do the same min- 
eralogical and physical features that are found in these parts, 
continue to very great depths. In considering this superficial 
alteration, we discuss a subject analogous to the secular decay of 
rocks. The latter, however, involves usually but a limited num- 
ber of common rock-forming minerals, while the secular decay 
of ore deposits involves a great variety of minerals, not only the 
oxides, carbonates and silicates common in most rocks, but also 
sulphides, arsenides, tellurides, selenides, antimonides, chlorides, 
bromides, iodides, fluorides, sulphates, phosphates, tungstates, 
molybdates, and numerous other classes of minerals, many of 


* This has been shown by J. H. L. Vogt (Zeitschrift fiir praktische Geologie, Jan- 
uary, 1893) to be true of certain titaniferous iron ores and other deposits in the eruptive 
rocks of Norway. It may also be true of certain titaniferous iron ores in the United 
States. 


290 THE JOURNAL OF GEOLOGY. 


which, under surface influences, give rise to intricate chemical 
changes. In discussing the subject of the superficial alteration 
of ore deposits, therefore, we treat a similar, but much less 
understood, subject than the superficial alteration of rocks. 

Technical names of alteration products —The altered surface out- 
crop of ore deposits is known by various names in different 
regions. Among the Cornish miners of England it is known as 
gossan, a name which has also been adopted into American 
mining nomenclature, though other special names are given in 
special classes of deposits. In France it is known as chapeau de 
fer; in Germany as eisener hut; among the Spanish Americans 
as pacos or colorados. As almost all deposits contain more or 
less iron minerals, the outcrops are usually stained brown from 
their oxidation, and hence the reference to iron in the French 
and German names. Sometimes, however, the outcrops are 
stained black by the oxidation of manganese carbonate or sili- 
cate, or green by copper minerals, or other colors by the forma- 
tion of other compounds. 

Agents of alteration—The superficial alteration of ore deposits, 
as of any rock, results from a combination of mechanical and 
chemical disintegration, brought about by the combined action 
of the atmosphere, surface waters, changes in temperature, and 
the various organic and inorganic materials contained in the air 
and water. In nature, we never deal with perfectly pure water, 
but different waters contain different ingredients derived from 
the air and from the different materials with which they come in 
contact. Among the most important of these ingredients are 
oxygen, numerous organic acids like carbonic, oxalic, malic, 
citric, formic, propionic, butyric, acetic acids, etc., certain inor- 
ganic acids, such as sulphuric, nitric, hydrochloric, hydrobromic, 
etc., etc. Some of the acids mentioned occasionally occur in the 
free state, but most of them are generally combined with some 
of the bases present, such as the alkalies, lime, magnesia, iron, 
alumina, etc. These various ingredients, of course, are not all 
contained in the same waters, but are found in various associa- 
tions in different waters. The organic acids mentioned represent 


SUPERFICIAL ALTERATION OF ORE DEPOSITS. 291 


various stages of oxidation of materials from organic matter, but 
they all eventually, if allowed to become completely oxidized, 
pass into carbonic acid; while if they are in combination with 
different bases, these salts are eventually converted to car- 
bonates. 

Method and chemical effects of alteration—Surface waters thus 
charged with various chemical ingredients percolate down into 
ore deposits, and there meet various materials which are even 
less stable under their influence than most of the common rocks. 
The alteration, therefore, is comparatively rapid, and, though 
only superficial, generally extends to much greater depths than 
in the surrounding country rock. From a chemical standpoint, 
the first effect of this superficial influence is usually the oxida- 
tion or hydration, or both, of certain ingredients, followed gen- 
erally by the formation of other chemical combinations and by the 
leaching of certain materials. In the formation of these other 
chemical combinations, however, the base usually remains the 
same, and the alteration consists generally in a change of the 
materials associated with the base, that is, in the acidic portion 
of the mineral or the part that represents the acidic portion. 
Thus, iron sulphides are oxidized to iron sulphate, and then this is 
converted by further oxidation and by hydration to the hydrous 
sesquioxide. Copper sulphides may be oxidized to copper sul- 
phate ; and from the sulphate, by the agency of materials in sur- 
face waters, may be formed copper carbonates, haloid com- 
pounds, silicates, oxides, and even metallic copper; while from 
some of these, still other compounds may be produced. Similar 
reactions occur in many lead, zinc, silver, gold, and other deposits. 

Occasionally, chemical changes may occur without previous 
oxidation, and sometimes, though rarely, surface influences 
under peculiar conditions may havea reducing effect, as in the 
formation of iron pytites and copper pyrites from the sulphates 
of iron and copper, or in the formation of native copper by the 
action of a ferrous salt on certain copper salts, or in the forma- 
tion of native silver in surface outcrops. In many of such cases, 
however, the chemical action is primarily one of partial oxida- 


292 THE JOURNAL OF GEOLOGY. 


tion, and the reducing action follows as the effect of one of the 
partially oxidized compounds on the other, as in the case of 
copper just mentioned. In deposits, such as gypsum, a reduc- 
tion, due sometimes to superficial influences, is seen in the occa- 
sional formation of sulphur from gypsum. 

An important chemical effect of surface influences is the 
removal in solution of certain ingredients of the ore deposit 
which are soluble in surface waters ; as the removal of the cal- 
cite gangue of many silver and other deposits; the oxidation and 
removal of the sulphur in various silver, lead, zinc, copper, and 
other deposits; the oxidation and removal of both the iron and 
sulphur of iron pyrites in auriferous quartz veins ; the removal 
of silica from certain iron deposits, such as those in the Lake 
_ Superior region, etc. Probably many phosphate deposits are 
formed by the superficial leaching of carbonate of lime from cal- 
careous beds, and the corresponding concentration of phosphate 
of lime once finely disseminated in the same beds. 

Another chemical effect of superficial alteration is seen in the 
occasional formation of mineral deposits of importance by cer- 
tain materials carried from outside sources and deposited in a 
rock of otherwise no commercial value. Thus certain phosphate 
deposits of the South Pacific Ocean, the West Indies and possi- 
bly of Florida, are formed by the leaching of soluble phosphates 
from guano, their transportation down into underlying limestone 
or coral reefs, and the precipitation of the phosphoric acid as 
tribasic phosphate of lime, which, being almost insoluble, arrests 
further escape of the phosphatic materials. 

Again, another chemical effect is seen in the incrustations, 
and even extensive beds, of saline materials, like borax, nitre 
and the various alkaline salts of the western arid regions, formed 
by precipitation from water rising by capillary action through 
the soil, becoming evaporated on the surface and depositing the 
saline materials which they have dissolved from below. Many 
saline deposits are formed by the simple evaporation of surface 
waters, such as lakes, seas, etc., but certain deposits undergo 
only an initial concentration in this way, and are laid down with 


SUPERFICIAL ALTERATION OF ORE DEPOSITS. 293 


clay, sand, and gravel, while further concentration is due to this 
capillary action. In the case of nitre, indeed, the saline material 
is very often, if not generally, formed in soils or guano beds and 
undergoes its first concentration by this capillary action. 

In the various chemical changes mentioned above, the class 
of salts that remains, whether oxides, carbonates, haloid 
compounds, etc., varies with the nature of the bases affected. 
Thus, iron sulphides and copper sulphides are both oxidized 
and form sulphates. But here the similarity of their behavior 
ends, for the iron sulphate probably passes then into a basic sul- 
phate and then into a hydrous sesquioxide, while the copper sul- 
phate takes up carbonic dioxide and water and forms basic car- 
bonates. The iron sulphate might, under certain conditions, 
form a carbonate in a similar manner, but this compound would 
be very unstable under the conditions existing in the alteration 
of sulphide deposits and would quickly go into the form of the 
hydrous sesquioxide, while the carbonate of copper is stable 
under existing conditions and remains. 

In the same way, if silver sulphide and iron sulphide are both 
oxidized and then affected by waters carrying common salt or 
other chlorides in solution, the silver is converted to chloride, 
which is insoluble and remains; while the chlorides of iron are 
much less liable to be formed, as they are soluble, and some of 
them unstable, compounds, and even if they were formed, they 
would be leached out or oxidized. Hence, though chloride of 
silver is a common product of alteration in silver deposits, chlor- 
ide of iron is never found, at least to any extent, as a product of 
alteration of iron deposits. 

Again, it is frequently found that unaltered auriferous iron 
pyrites contains a certain amount of silver, while the altered part 
often carries almost none. In such cases, the gold has remained 
stable during the alteration, while the silver, in the absence of a 
chloride or other reagents to convert it to an insoluble compound, 
has been dissolved and carried away in solution by the acid 
materials generated during alteration. 

Hence, the materials in surface waters affect different bases 


294 THE JOURNAL OF GEOLOGY. 


differently, and, therefore, there is a great difference in the 
classes of salts formed by the same surface waters on the ores of 
different metals. In the same deposit there may be formed an 
oxide of one metal, a carbonate of another, a chloride of another, 
etc. In fact, in some of the silver deposits of southern New 
Mexico, there can be found hydrous sesquioxide of iron formed 
from iron sulphide, carbonates of copper formed from copper 
sulphides, and chloride of silver formed probably from silver 
sulphides, and yet in all probability the same surface waters pro- 
duced all these changes practically simultaneously. 

Asa result of these various changes, certain materials are 
sometimes leached from the upper parts of ore deposits, which 
have become porous by alteration, and carried down to the less 
_ pervious unaltered parts. Here they are precipitated by meet- 
ing other solutions or in other ways, and hence the richest 
bodies of ore in a deposit often occur between the overlying 
altered part and the underlying unaltered part. This is not 
always the case, but it is true of some copper, silver, iron and 
other deposits. 

Physical effects of alteration —F¥rom a physical standpoint, the 
effect of superficial alteration is generally to make the deposit 
more open and porous, to cause it to shrink, and, in some cases, to 
convert it to a loose material of the consistency of sand and clay. 
In some cases, however, especially where considerable hydration 
goes on, an expansion may be caused. This is well seen in the 
formation of gypsum by the hydration of anhydrite, often caus- 
ing an expansion sufficient to brecciate and fold the associated 
rocks,, and amounting to about 33 per cent. of the original 
material.? In the conversion of carbonate of iron to the hydrous 
sesquioxide of iron, or limonite, it has been found that there isa 
contraction of 19.5 per cent., giving the deposit the loose porous 
structure characteristic of limonite and forming the familiar 

TELIE DE BEAUMONT, Explic. Carte géol. de France, Vol. Il., p. 89. R.A. F. 
PENROSE, JR., Arkansas Geol. Survey, 1890, Vol. I, pp. 535-538. 

2 A. GEIKIE, Text Book of Geology, 3d Edition, p. 345. 

3T,. STERRY HuNg, Mineral Physiology and Physiography, 1889, p. 262. 


SUPERFICIAL ALTERATION OF ORE DEPOSITS. 295 


limonite geodes.* In this case carbon dioxide has been removed 
from the iron, but oxygen and water have been added. A poros- 
ity is also produced by the removal of certain ingredients in ‘an 
ore deposit without the addition of others, as in the oxidation 
and leaching of iron pyrites in veins of auriferous quartz, leaving 
a loose, porous, spongy quartz mass. 

Surface decomposition has also, in many places, not only 
affected the ore deposit itself, but also the country rock in the 
immediate vicinity, and has converted it into a loose material of 
a sandy or clayey consistency, as at Iron Mountain, Missouri, in 
the Batesville manganese region of Arkansas and in other local- 
ities described beyond. In the iron and manganese deposits of 
the Cambrian and Lower Silurian rocks in the Appalachian 
region, the limestones and shales, which once enclosed the ore 
bodies, have often been converted to clay in the same way as in 
the Batesville region; and, in fact, the common mode of occur- 
rence of these deposits is as residual clays carrying irregular 
bodies and nodules of ore. 

This decay of the country rock in immediate association with 
ore deposits, is generally more extensive than in similar rocks 
not associated with such deposits, and, therefore, requires further 
explanation than the simple action of ordinary surface waters. 
The explanation is, doubtless, in many cases, that the rock has 
decayed under the influence of the same waters that originally 
concentrated the ore; and as these waters differed from most 
waters in character and in the materials they held in solution, 
they often had an abnormal effect. Moreover, when subsequently 
the ore body is affected by surface influences, sulphuric acid is 
liberated from sulphides and carbonic acid from carbonates, as 
well as other acids from other minerals, and all these materials 
have an active effect on most rocks. Moreover, the porous nature 
of many ore deposits, after they have been altered on the surface, 
allows a freer percolation of surface waters than elsewhere in the 
same country rock, and, hence, a correspondingly greater decay. 


™R. A. F. PENROSE, JR., The Tertiary Iron Ores of Arkansas and Texas, Bulletin 
Geological Society of America, Vol. 3, 1891, pp. 44-50. 


296 THE JOURNAL OF GEOLOGY. 


Another physical effect of surface influences on ore deposits 
is seen in certain forms of brecciation due to physical or chemi- 
cal causes, such as expansion by hydration, etc. Such breccia- 
tion, however, has usually occurred in the country rock before the 
concentration of the ore deposit; in fact its existence, by offer- 
ing favorable conditions for deposition, has often been the cause 
of the formation of the ore deposit ina given place. Though 
brecciation, therefore, is very important as a factor in the con- 
centration of ore deposits, it does not belong, to any large extent, 
in a discussion of the surface alteration of ore deposits after their 
formation, and, therefore, it will not be treated further in this paper. 

Depth of alteration.—Having thus discussed briefly the means 
by which superficial alteration in ore deposits is produced, and 
the results of this alteration, the next feature to be taken up is 
the depth to which it extends. As already shown, the alteration 
is primarily one of oxidation and generally of hydration; and, 
though either may occur without the other, they both very often 
occur together. When surface waters percolate into the rock, 
their influence is more active near the surface, because they carry 
large quantities of oxygen, and because the oxygen of the air 
itself also has some influence. As they sink deeper, the effect 
of the oxygen of the air becomes less active, and the oxygen 
dissolved in the water is consumed in oxidizing various materials 
which it meets on the way, until finally most of the oxygen is 
lost and active oxidation ceases. Theoretically, this oxidizing 
action may extend down as far as, and sometimes below, the level 
of the drainage of the surrounding country, which is called also 
the zone of permanent saturation. Above that level, there is a 
constant circulation of water from the surface downwards, thus 
affording means of active oxidation; but when the water reaches 
that level, not only has most of the oxygen contained in solution 
generally been used up, but also the circulation of the water is 
much more sluggish, so that oxidation is less active." 


tIt is possible that the oxidation near the surface is due largely to free oxygen in 
the waters, while, when this becomes exhausted at a depth, the oxidation may be due to 
the abstraction by mineral matter of the oxygen in combination with materials in 
solution. 


SUPER CIAL AE RE RATHON OF ORE DEPOSITS. 297 


The process of hydration, when the materials affected do not 
require oxidation before they can become hydrated, may extend 
down indefinitely below the limit of oxidation; but when oxida- 
tion is necessary before hydration is possible, the latter process 
of course can extend no deeper than oxidation. Thus the silicate 
of alumina in feldspar may become hydrated and form kaolin 
without the intervention of oxygen. This is brought about by 
the action of carbonic acid and water, which react on the feldspar 
and form alkaline carbonates, kaolin and free or hydrous silica. 
Theoretically, therefore, kaolinization ought to go on to any 
depth that can be reached by water and its almost universal 
accompaniment, carbonic acid. In this case, however, the base 
in question is already in its peroxide condition (Al, O,), but 
when a base is not in this condition, it frequently requires oxida- 
tion previous to hydration. Thus sulphide of iron does not 
become hydrated until it is peroxidized, and this mineral, there- 
fore, requires oxidation previous to hydration.* 

The various materials other than oxygen in surface waters 
have a very important effect on the mineral matter with which 
they come in contact, and their action sometimes takes place 
before that of oxidation, though it often requires at least a par- 
tial previous oxidation. The effect is both to form new chemical 
compounds with the materials involved, and to dissolve and 
bodily remove certain materials. As with oxygen, however, so 
with these other agents of alteration, they are more active above 
the drainage level of the country than below it, and an additional - 
reason for this is that many of the materials affected require a 
primary oxidation before they enter into other chemical combi- 
nations. Thus sulphide of lead is oxidized to sulphate of lead 
before it can take up carbonic acid and form carbonate of lead; 
while on the other hand, carbonate of lime can be converted to 
sulphate of lime (gypsum) by the action of sulphuric acid or 
certain sulphates without any change in the degree of oxidation 
of the lime. 


t For a full discussion of this subject see H. Rose, Ueber den Einfluss des Wassers 
bei chemischen Zersetzungen, Pogg. Ann. der Physik und Chemic, 82 et seq. 


298 THE JOURNAL OF GEOLOGY. 


It will thus be seen that in going from the surface downwards, 
we pass from a zone of active oxidation into a zone in which oxi- 
dation practically ceases. Below the level of permanent satura- 
tion, the waters may sometimes gradually sink to very great 
depths, even deep enough to become intensely heated and possi- 
bly dissociated. Such water may have a very important effect in 
the formation of ore bodies, though in a manner quite different 
from their action on the surface. The present discussion, how- 
ever, relates not to this, but to only superficial influences. 

Though theoretically, therefore, alteration of one kind or 
another may extend down to, and in some cases much below the 
level of permanent saturation, and if given sufficient time would 
actually go to such depths; yet in many, if not most, cases it 
has not yet reached that level. The actual depth to which alter- 
ation does extend varies with the topographic conditions of the 
region, the chemical nature and the porosity of the deposits 
affected, the character of the climate, and other minor con- 
ditions. 

The topography of a region affects the depth of alteration, 
because it is one of the principal features in determining the 
depth of permanent saturation. The chemical nature of the 
deposit affects the depth of alteration because on this depends 
the degree of resistance it will offer to the chemical effects of 
percolating waters. The porosity of the deposit affects the depth 
of alteration because, in deposits of similar kind but of different 
porosity, the more porous will be more accessible to surface influ- 
ences, and will, therefore, be more affected, in a given time, than 
the less porous deposit. 

The climatic conditions, such as the amount and manner of 
occurrence of rainfall and other forms of atmospheric moisture, 
and the rate and degree of variation in temperature have a large 
influence on superficial alteration. On the amount of rainfall 
and other forms of atmospheric moisture depends the amount of 
moisture available as an agent of alteration ; while on their mode 
of precipitation depends, other things being equal, the amount of 
water which would sink into the deposit, thus effecting alteration, 


SUPERFICIAL ALTERATION OF ORE DEPOSITS. 299 


and the amount that would immediately run off the surface or be 
evaporated and thus have but little altering effect. The rate and 
degree of variation in temperature affect the amount of breaking 
in the rock by expansion and contraction, and, therefore, the 
accessibility of the rock to surface influences. The character of 
the climate also influences, to a certain extent, the nature and 
amount of vegetation, and from the vegetation are obtained many 
organic acids which assist the action of surface waters. In other 
ways, also, such as in the generation of nitric acid in the atmos- 
phere, the character of the climate influences the agents of alter- 
ation. 

As a result of all these influences, surface alteration is found 
to extend in different ore deposits to depths varying from only a 
few inches, or in fact only a fraction of an inch, to several hun- 
dred and even a thousand or more feet. In glaciated regions 
the products of decay have often been swept away by glacial 
action, and the time which has elapsed since then has not been 
sufficient for alteration to have extended to any great depths; 
while in regions of moist climates, the erosion sometimes, though 
not always, keeps pace with the alteration, so that the depth of 
the.change is shallow. In those regions, however, which have 
not been recently glaciated and which have dry or only moder- 
ately moist climates, so that erosion is slight, or in places which 
have moist climates, but which, on account of their topography, 
are not subjected to very active erosion, the products of altera- 
tion collect, and the changes are traceable downwards often to 
great depths. 

In the copper regions of Michigan, the deposits have been 
exposed to glaciation, and are still exposed to the active effects 
of erosion in a moist climate, so that here, though the native 
copper of the region is a material very easily affected by surface 
alteration, yet the only change observable is a slight stain of cop- 
per carbonate or oxide on the surface of some of the native 
copper, and even this is not always present. On the other hand, 
in the arid region of the west, most of which has not been 
recently glaciated and which has an exceedingly dry climate, the 


300 THE JOURNAL OF GEOLOGY. 


residual products of alteration have accumulated to great thick- 
nesses. This region, however, had once a much more moist 
climate than now, and some of the alteration may have occurred 
then. Many of the Arizona copper deposits in this region 
originally contained their copper in the form of copper pyrites, 
which, under similar conditions, is probably more resistant to sur- 
face alteration than the native copper.of. Michigan, and yet it has 
been changed to various other copper minerals for depths often 
feaching; {rom LOO" to over ool feet. In Chile some or) the 
copper sulphide deposits are said to have been altered to a 
depth of 1,500 feet, but it is very rare that much alteration 
extends in any ore deposits to greater depths than this. In the 
more moist climate of Tasmania, the results of alteration are also 
_very marked. 

The depth of alteration of ore deposits in unglaciated regions in 
the United States varies from a few feet to over 1,000 feet. In the 
Appalachian region, many of the deposits of auriferous quartz, iron 
pyrites, copper pyrites, etc.,are altered to depths varying from less 
than one to a hundred feet or more. Many of the Clinton iron ore 
deposits are altered to still greater depths. The depth of altera- 
tion in these Appalachian deposits is usually much greater, other 
things being equal, south of the limit of glaciation than north of 
it. In the silver, lead, gold, and copper deposits of the Rocky 
Mountains and the western arid region, such as at Butte City, 
Leadville, Central City, Cripple Creek, Silver City, Lake Valley, 
Eureka, Virginia City, Park City, the Coeur d’Alene district, and 
elsewhere, the alteration has reached depths ranging from 50 to 
600 or 700 feet, and in some rare cases still more. At Granite 
Mountain in Montana, signs of alteration are seen in the argen- 
tiferous quartz deposits of that region, even at depths of goo feet, 
though of course at such depths the alteration is slight as com- 
pared with that nearer the surface. 

Complete alteration rarely extends to these greater depths, 
and usually parts of a deposit which have as yet escaped altera- 
tionappear comparatively near the surface. These are at first very 
few and may be entirely enclosed by altered products, but with 


SUPERFICIAL ALTERATION OF ORE DEPOSITS. 301 


increased depth they become more numerous and continuous, until 
they predominate over the altered products, and finally, when the 
limit of alteration is reached, they entirely replace them. The 
planes of contact between an ore deposit and the country rock, 
that is the walls, afford, when well defined, easy passages for the 
downward percolation of surface waters, and therefore alteration 
frequently continues down along these lines for considerable dis- 
tances after the limit of alteration in the main part of a deposit 
has been reached. Any other possible channels, such as the 
planes of contact of different minerals in banded deposits or the 
series of drusy cavities often found in the central parts of ore 
deposits, may act in the same way as passages for water. Hence 
the not infrequent abundance of alteration products, such as 
hydrous sesquioxide of iron, and native copper and silver, along 
the walls and elsewhere in certain deposits. 

Classification of the products of alteration—TYhe products of 
superficial alteration may be divided into two general classes: 
(1) Those which occupy the same position as the materials from 
which they were derived, or are only slightly removed, and 
possess the same general environment. Thus the altered out- 
crops of auriferous quartz and iron pyrites, of argentiferous 
galena, of sulphides of copper and many other similar deposits, 
represent alteration-products occupying the same general posi- 
tion as the original sulphide ores ; while the iron ore bodies of 
the Lake Superior region represent alteration-products changed 
somewhat in position from that occupied originally, but yet in 
the same series of rocks and sometimes with somewhat similar 
environment. (2) In the second class are included those deposits 
which have been entirely removed from their original position 
and redeposited under totally different environments. Thus, 
placer gold deposits, stream tin, most of the deposits carrying 
platinum and the allied metals, magnetic and chromite sand, 
the gravels and sands carrying precious stones, and many other 
similar deposits represent this class. They have been derived 
by the decay and erosion of veins, dikes or country rocks carry- 
ing the materials now concentrated in these fragmental deposits. 


302 UES, JOURNAL OF GEOLOGY. 


The materials in their original environment may or may not 
have been sufficiently concentrated to serve as commercial 
sources of supply, but the fragmental deposits mentioned almost 
always represent a further concentration. This class of deposits 
is of great importance, but the present discussion relates more 
especially to the superficial alteration of deposits that remain 
zn situ, and therefore these will be treated more in detail than 
the other class, (No. 2), though the latter will be mentioned as 
occasion requires. 


SUPERFICIAL ALTERATION IN DIFFERENT DEPOSITS. 


Alteration tn tron deposits—It was once generally believed that 
most iron deposits were the result of direct precipitation from 
aqueous solution, or in rarer cases, were igneous masses. It has 
long since been shown, however, that most workable iron depos- 
its are the result of a concentration subsequent to their deposi- 
tion, while very few are due to a direct precipitation during the 
formation of sedimentary rocks, though some may be due to a 
process of differentiation in the cooling of eruptive magmas. * 
The original presence of the iron in sedimentary rocks was doubt- 
less due to a direct precipitation during the formation of the 
enclosing rock, but it was then in a finely disseminated condi- 
tion, and it was only by being subsequently taken into solution 
again by percolating waters and concentrated, that it was con- 
verted into bodies of greater or less purity. Generally, though 
possibly not always, this process is superficial, and though it may 
extend to a depth of several hundred or even a thousand feet or 
more, it can be traced directly to surface influences, and its 
effects are seen to decrease gradually with depth. Shaler,? in 
1877, showed that some of the limonites of Kentucky, Ohio and 
elsewhere were concentrations of iron derived in solution from 
shales and other rocks and reprecipitated in underlying lime- 
stone. 


t See foot note on second page of present article. 


2N. S. SHALER, Kentucky Geol. Survey, Report of Progress, Vol. III., New 
Series, 1877, p. 164. 


SUPERFICIAE ALTERATION OF ORE DEPOSITS. 303 


Van Hise,’ in 1889, showed that the iron deposits of the Lake 
Superior region are concentrations of iron formerly disseminated 
in a siliceous rock containing carbonate of iron and other carbon- 
ates, and called by him cherty iron carbonate. This dissemin- 
ated iron was taken into solution by surface waters, carried down 
until its passage was obstructed or impeded by less pervious 
rocks, often dikes, and there precipitated by meeting with other 
solutions of a different nature. These other solutions contained 
oxygen, while the iron-bearing solutions had been largely robbed 
of their oxygen and had been freed from silica by the large 
amount of carbonic acid they contained. When, therefore, the 
two solutions met, the iron in solution was oxidized and pre- 
cipitated ; while the silica, in the spot where this precipitation 
occurred, was, on account of the dilution of the carbonated 
waters with the other waters, and through the agency of alkaline 
carbonates, dissolved and carried off, thus gradually increasing 
the amount of iron and removing the silica. By this theory, the 
iron is largely a replacement of the silica of the cherty iron car- 
bonates, and has been derived from the parts of the strata 
exposed to superficial influences. The deposits are, therefore, 
of only superficial extent, though they may reach over 1,000 
feet below the surface, yet when they pass below the action of 
surface influences, the iron has not been concentrated and they 
are of too low grade to be mined for iron ore. The methods of 
local concentration proposed by Professor Van Hise for these 
Lake Superior iron deposits, are equally applicable to certain 
other iron deposits, and are a most valuable addition to our 
knowledge of chemical geology. They also bring out in a most 
prominent manner, the fact that even rocks composed of mate- 
rials like silica, which are very resistant to surface influences, may, 
under proper conditions, be replaced on a large scale. 

*C. R. VAN HisE, The Iron Ores of the Penokee-Gogebic Series in Michigan and 
Wisconsin, Amer. Jour. Sci., 3d series, Vol. 37, 1889, pp. 32-47; The Iron Ores of 
the Lake Superior Region, Trans. Wisconsin Acad. Sci., Vol. VIII., 1891. For a 
fuller discussion by Van Hise on this subject see United States Geol. Survey, Tenth 


Annual Report, 1888-89, Pt. I., pp. 409-422; Monog. U.S. Geol. Survey, No. XIX., 
1892. 


304 THE JOURNAL OF GEOLOGY. 


The iron deposits of the Mesabi Range in Minnesota, which 
have lately been described by H. V. Winchell? are supposed to 
have had a somewhat similar origin to that given for the Michi- 
gan and Wisconsin ores by Van Hise. Winchell believes that 
they are due to the concentration by surface agencies of iron 
disseminated as oxides in a highly siliceous rock, and that in this 
concentration the silica has been replaced by iron. 

The red hematites of the Clinton horizon of the Upper Silu- 
rian in the Appalachian region have been at least partly formed 
by superficial concentration which extends to only limited depths. 

The iron deposits in other geologic horizons of the Appala- 
chian valley, especially in the Cambrian, Lower Silurian and 
Carboniferous rocks, are also often much changed by the action 
_of surface influences. Many of the deposits in the Cambrian 
and Lower Silurian can be clearly shown to be due to a super- 
ficial replacement of limestone, or even of more siliceous rocks 
like shales, by iron dissolved from ferruginous rocks in the neigh- 
borhood. In such cases, the iron in the original rock has been 
dissolved and carried off in carbonated surface water, and re-pre- 
cipitated in the other rocks, all these stages being directly due to 
surface influences. Many of the carbonate iron ores of the Car- 
boniferous rocks are rendered not only of higher grade, but also 
more easy to treat, by the oxidation of the carbonate to the 
sesquioxide and the removal of the carbonic acid. Moreover, 
these carbonate ores often occur as nodules, ‘‘ kidney ores,” in 
shale, and, on the surface, this shale has been softened by atmos- 
pheric conditions, thus facilitating mining; while away from the 
surface, the shale becomes harder and makes mining more expen- 
sive. 

Surface influences on carbonate of iron have been made use 
of artificially in Styria, where a very hard spathic iron ore has 
been mined and spread out ona hill side for from 20 to 25 years. 
By this process the ore was oxidized and made more porous, and 
thus became very much more cheaply treated.” 

* Minnesota Geological Survey, Twentieth Annual Report, pp. 136-148. 

* Letter from Mr. CHARLES E. SMITH, Philadelphia, Pennsylvania. 


SUPERFICIAL ALTERATION OF ORE DEPOSITS. 305 


At the celebrated Iron Mountain in Missouri, a large part 
of the ore came from conglomerates composed largely of frag- 
ments of iron ore, which had been weathered out of the pre-Cam- 
brian rocks that had originally contained them. These conglom- 
erates lie at the base of the Cambrian strata which overlie the 
pre-Cambrian rocks, and even in the latter rocks, where exposed, 
the original ore has been made much more easy to work by the 
decay of the enclosing material and its conversion to clay. 

In the iron region of eastern Texas, the limonite ores are often 
a result of the solution of iron from the superficial oxidation of 
iron pyrites, iron carbonate and glauconite. Sometimes the 
sequel of this process is the downward passage of the solution to 
an underlying laminated clay, and the gradual replacement of 
this bed, forming a hard limonite,! which still preserves the lam- 
inated structure of the clay. 

In Mexico certain hematite deposits described by R. T. Hill? 
as occurring in Lower Cretaceous limestone at or near the con- 
tact with intrusive masses of diorite, and sometimes even in the 
diorite itself, may, as Hill suggests, be the result of superficial 
concentration from the limestone. 

Very large deposits of hematite also occur in Grant county, 
New Mexico, at the contact of limestone and an eruptive: >) he 
origin of this ore is as yet somewhat obscure, but is probably 
due to a concentration after the original deposition of the iron. 

The iron deposits in the lakes of Sweden and Norway are 
most striking instances of a concentration of iron ore due to sur- 
face influences and going on at the present time. The iron is 
derived from the oxidation of the neighboring rocks, carried by 
carbonated surface waters to the lakes, and there, by further oxi- 
dation and hydration, precipitated as hydrous sesquioxide (lim- 
onite). The iron ore is dredged up and used, but the processes 
of nature gradually replace it, and, in the course of years, the 
lakes again accumulate a considerable thickness of ore. 

*R, A. F. PENROSE, JR., Geological Survey of Texas, First Annual Report, 1890, 
pp. 72-76, 79-81; also Bulletin Geological Society America, 1892, pp. 47-50. 
? Amer. Jour. Sci., Vol. XLV., 1893, pp. I11—120. 


306 LHE JOURNAL OF GEOLOGY: 


Many other similar cases of superficial enrichment in iron 
deposits might be mentioned, but the above are enough to illus- 
trate the point in question, and it will be seen that, of the regions 
which are the active producers of iron ore in this country, almost 
all, if not all, owe the existence, or at least the availability of 
their large bodies of ore, to superficial concentration. 

Alteration in manganese deposits.— Manganese deposits are 
affected by superficial influences in much the same way as iron 
deposits. Many of the manganese deposits in the Cambrian and 
Lower Silurian rocks of the Appalachian Valley were concentrated 
in a manner somewhat similar, though not always so, to the iron 
deposits in the same regions." 

In the Batesville manganese region of Arkansas, the ore 
_ originally occurred in irregular masses in Silurian limestone, but 
surface decay has leached the carbonate of lime out of the lime- 
stone, leaving a red siliceous clay, which represents the less solu- 
ble part of the original rock. This clay now lies in hollows on 
the surface of the limestone and contains the masses of ore once 
disseminated through that rock. The removal of the carbonate 
of lime has concentrated the ore masses in the clay, and has also 
rendered them more easily mined ; in fact, the only manganese 
ore that can now be profitably mined in this region is that in the 
residual clay.? 

The frequent occurrence of deposits of bog manganese ore 
in the areas of crystalline rocks, generally represents a concen- 
tration of manganese resulting from the oxidation of dissemin- 
ated carbonate and silicate of manganese in the country rock. 
This oxidation product is taken into solution in surface waters, 
and transported until subjected to such conditions that it is oxi- 
dized and precipitated as a hydrous oxide. 

Alteration in copper deposits —In many copper deposits super- 
ficial alteration has produced very remarkable chemical and 
economic results, and this is especially well seen in the copper 


TR. A. F. PENROSE, JR., Journal of Geology, No. 4, Vol. I., 1893, pp. 356-370. 


2R, A. F. PENROSE, JR., Manganese: Its Uses, Ores, and Deposits; Arkansas Geol- 
ogical Survey, 1890, Vol. I., pp. 166-209. 


SUPERFICIAL ALTERAFION OF ORE DEPOSITS. 307 


sulphide deposits of Arizona, Chile and elsewhere. In Arizona 
the upper parts of the deposits are composed of brown or black 
ferruginous masses, with brilliantly colored oxidized copper min- 
erals, as cuprite, malachite, azurite, chrysocolla, etc.; while below, 
at depths varying from a few feet to several hundred feet, the 
deposits usually pass into a mixture of copper pyrites and iron 
pyrites, the latter usually being far in excess. Sometimes other 
copper sulphides occur, either mixed with copper pyrites or free 
from it, and they may or may not have been derived from it. 
Here the carbonates and some of the other alteration minerals 
contain not only more copper than the unaltered copper pyrites, 
but they are also in a much more concentrated condition than 
the sulphide which is disseminated through iron pyrites. The 
total amount of copper has not been increased, in fact it may 
be decreased by leaching, but it is in a more concentrated 
form, and therefore the ore obtained from these concentrations 
averages from eight to thirty per cent. or more in copper, while 
the mixture of unoxidized copper pyrites and iron pyrites below 
averages only about five per cent. in copper. Moreover, the 
altered ores are much more cheaply treated than the unaltered 
ones, and are therefore still more desirable. It will thus be seen 
that the economic value of the deposits as a whole has been 
greatly increased. 

In the surface alteration of these deposits, the copper sul- 
phides have first been converted to copper sulphate and then, by 
the action of surface waters and the materials contained in solu- 
tion in them, they pass into the forms of copper carbonates, 
oxides, silicates, and occasionally to the chlorides and bromides, 
and sometimes to native copper. The iron sulphide is first con- 
verted to sulphate and then this, through other stages, is 
converted into the hydrous sesquioxide (limonite), though 
the iron sometimes now occurs in the form of the anhydrous 
sesquioxide (hematite). This may have been derived from 
the limonite by dehydration, or, under certain conditions, 
may have been formed directly by the oxidation of iron 
pyrites. The oxidized copper minerals in the upper part of 


308 LE JOURNAL OM NGHOEOGN: 


the ore deposit have been concentrated partly by segregation 
during alteration, and partly by the leaching of the asso- 
ciated materials. As a result of this, these minerals occur as 
seams, pockets or irregular bodies, often a hundred feet or more 
in diameter, generally enclosed by, and often intimately asso- 
ciated with, the oxidized iron materials which represent the 
gangue. 

In the case of the Arizona deposits, alteration has progressed 
just far enough to increase greatly the value of the deposits with- 
out to any extent injuring it. Such products of alteration, how- 
ever, are more or less soluble in surface waters containing various 
organic and inorganic compounds, so that in a moist climate there 
is a constant tendency to leach them out and leave only the less 
_ soluble parts of the gangue. In Arizona, this stage has not yet 
progressed to a noticeable degree, and one reason for this may 
be the extreme dryness of the climate, which affords opportunity 
for only comparatively slight percolation of surface waters. 

In the copper deposits of Montana and the Appalachian 
region, however, a further stage of alteration is often observable. 
The copper deposits at Butte City, Montana, are composed 
largely of chalcocite, with copper pyrites, bornite, enargite, iron 
pyrites and other minerals in a siliceous gangue. On the surface 
the copper in these deposits has been almost entirely oxidized 
and leached out, and the ore consists of a porous, rusty, siliceous 
mass which was once mined for the small percentage of silver it 
contained. As depths were reached, the oxidized copper min- 
erals began to appear, and eventually the sulphides formed the 
mass of the veins. In this case, a further stage of alteration is 
seen than that in Arizona. 

At Ducktown in eastern Tennessee,’ deposits of mixed iron 
and copper pyrites occur and have been altered in a somewhat 
similar manner on the surface. The copper minerals have been 
leached out of the ferruginous gangue in the upper parts of the 
deposits, and for a depth of from 20 to 80 feet or more, the 
deposits are composed simply of a porous mass of more or less 


tJ. D. WuHitNneEy, The Metallic Wealth of the United States, pp. 322-324. 


SUPERFICIAL ALTERATION OF ORE DEPOSITS. 309 


hydrous sesquioxide of iron. Below this a part of the copper, 
which has been leached from above, has been carried down and 
deposited as a dark material, probably composed largely of 
oxides and sulphides of copper, and averaging sometimes 20 to 
25 per cent. or more in metallic copper. This material immedi- 
ately overlies the unoxidized mixture of copper and iron pyrites, 
which averages only from 2 per cent. to 4 or 5 per cent. in cop- 
per. The commercial copper mined in this region came from 
the part of the deposit below the iron capping and above the 
unoxidized sulphides. When this was exhausted, the mines had 
to be closed, for the unaltered sulphides were too poor to be 
utilized. 

In Chile, Peru, and elsewhere in South America, changes in 
copper deposits, somewhat similar to those described in the 
United States, frequently occur. In fact, the great reputation 
which Chile once had as a copper producer, was largely due to 
this surface alteration, for the oxidized ore once supplied a rich 
and easily treated source of copper, but when the mines reached 
the unoxidized sulphides, the ores became poor in copper and 
more difficult to treat, so that the copper industry of Chile began 
to decline. In that region, however, the oxidation has in some 
places extended down as far as 1,500 feet. 

Alteration in lead deposits —In the case of lead deposits, the 
mineral galena, which is the commonest ore, is frequently more 
or less altered on its surface outcrops and converted to the sul- 
phate (anglesite) and the carbonate (cerussite). The first 
product of oxidation is anglesite, but this is a soluble compound 
and readily unites with carbonic acid or soluble carbonates in 
surface waters, forming the carbonate of lead, or cerussite. In 
rarer cases, other lead minerals, like phosphates, may also be 
formed. 

Alteration in silver deposits —Galena deposits often contain sil- 
ver, possibly sometimes in the same condition of sulphide as the 
galena, and this material is altered at the same time as the lead, 
_ with the formation of native silver, chloride of silver (cerargyr- 
ite), bromide of silver (bromyrite), iodide of silver (iodyrite), 


310 THE JOURNAL OF GEOLOGY. 


and various other minerals. The native silver is formed, proba- 
bly, only after a preceding oxidation of the sulphide. Deposits 
carrying other unaltered silver-bearing minerals, such as the 
various silver sulphides, arsenides, antimonides, tellurides, etc., 
are, when exposed to surface influences, affected in much the 
same way as the silver in argentiferous galena. 

Alteration of zinc deposits —In the case of zinc, the most com- 
mon ore is the sulphide known as blende. This mineral, like 
galena, is generally oxidized on the surface, and forms by other 
chemical changes the carbonate (smithsonite), the basic car- 
bonate (hydrozincite), and the basic silicate (calamine), in a 
manner similar to that described in copper and lead ores. 

In the cases of both lead and zinc, oxidized ores are very 
desirable for metallurgical purposes, and are much sought after. 
To be sure, the carbonates, sulphates, etc., of lead and zinc con- 
tain less of these metals than the pure sulphides, but they occur 
in a more concentrated form than the sulphides, and, therefore, 
the ores containing them frequently carry as much or more of 
the metals than the ores containing the sulphides. Moreover, 
the oxidized ores are much more easy to treat and, therefore, 
have an additional value over the sulphide ores. 

Alterationin gold deposits—In the case of gold deposits, sur- 
face alteration has a most marked effect, and probably in no class 
of deposits is the change of more geologic and economic impor- 
tance. The typical unaltered condition of gold in nature is in 
association with iron pyrites in quartz, the gold being some- 
times in such association with the pyrites that it cannot be sep- 
arated by mechanical means, while in rarer cases, it can be so 
separated. The effect of surface oxidation on such a deposit, 
is first to convert the iron pyrites into a hydrated sesquioxide of 
iron, which premeates the white quartz, with which the pyrites 
is usually associated, and turns it into a rusty brown mass. The 
next stage is the gradual leaching out of the hydrous sesquiox- 
ide by the action of surface waters. The iron is, in this way, 
finally removed altogether, and the remaining product is a pure 
white quartz, containing the gold which was originally in the 


SiC MN OLALE PAT AR ATLON OP. ORE DE POSITS. 311 


iron pyrites, and which has remained stable during the oxidation 
and leaching of that mineral. Such quartz is usually porous and 
spongy, and is filled with cavities which represent the shapes of 
the original crystals of iron pyrites, and which, during an inter- 
mediate stage, have been partly filled with hydrous sesquioxide. 
This leaching, however, is rarely complete, and the quartz is 
usually stained brown on the surface. 

In gold deposits of this kind, other minerals, such as copper 
pyrites; galena, blende, etc., frequently occur, and when the 
deposit is affected by surface influences, these minerals act in 
the manner already described under copper, lead, and zinc. It 
is not uncommon to see gold-bearing quartz stained green by 
oxidized copper minerals, or black by manganese minerals. 
Sometimes, especially in the Rocky Mountain region, gold 
occurs in the form of a telluride instead of in iron sulphide, 
and in such cases, the telluride is oxidized and the gold set free 
from its combined state. The gold, in being freed from pyrites 
or other minerals, is not only concentrated by the removal of 
certain ingredients of the deposits, but it is brought into a condi- 
tion in which it is much easier to treat than the unaltered part of 
the deposit, and, therefore, the upper parts of most gold- 
bearing veins are greatly enhanced in value. The ore from 


b) 


these parts is known as “‘ free milling”’ ore, because it can gen- 
erally be ground and the gold extracted by direct amalgamation 
with mercury ; while the ore in the unaltered parts of the deposit 
cannot usually be thus easily extracted, but must be smelted or 
treated by chlorination or some other more or less expensive 
process. 

When such deposits as those described are eroded, the parti- 
cles of gold separate from the quartz and are concentrated in the 
streams as placer gold. These detrital deposits are the source 
of a large part of the gold of commerce, and, in fact, were once 
the source of most of it. Now, however, many of the richest 
placer deposits known have been exhausted ; and besides, the 
methods of treating the ores in the original deposits are better 
understood, so that the latter are supplying yearly a larger and 


312 THE JOURNAL OF GEOLOGY. 


larger percentage of the gold production of the world. Hence, 
it will be seen, that in gold deposits, surface alteration not only 
plays an important part in freeing the gold from the iron pyrites, 
but also in forming placer deposits. Detrital deposits similar to 
gold placers and carrying various other materials are not at all 
uncommon, as in the cases of the platinum group of metals, cas- 
- siterite, diamonds and many other gems, chromite and magne- 
tite sands, and, in fact, even with some of the more common ores, 
as with the iron conglomerate at Iron Mountain, Missouri. 
Alteration in tin deposits.—In tin deposits, the typical mode of 
occurrence of the metal is in veins, dikes, or country rocks, in 
the form of the oxide known as cassiterite. Cassiterite is not 
easily affected chemically by surface influences, so that it is not 
much changed by superficial alteration, but for this very reason, 
its concentration is most markedly affected by surface alteration, 
for in the erosion of tin-bearing deposits the masses of cassiter- 
ite are broken up and carried off mechanically by surface waters, 
to be deposited somewhere else in the form of gravel beds, 
instead of being dissolved and possibly disseminated. In this 
transition, the fragments of cassiterite are largely separated from 
the accompanying materials by reason of their greater specific 
gravity, and hence, gravel deposits rich in cassiterite frequently 
occur. These represent the stream tin of the miner, and have 
been formed in much the same manner as have the placer gold 
deposits. Some chemical action, however, has gone on in the 
tin ore itself, but this seems to have been simply a process of 
solution and redeposition, as is seen in the pseudomorphs of 
cassiterite after other minerals and in the impregnations of 
animal remains in Cornwall, such as antlers, with oxide of tin.? 
Alteration in antimony deposits—In many antimony deposits, 
alteration similar to that described in some of the deposits already 
mentioned frequently occurs. The metal occurs most commonly 
as the sulphide known as stibnite. By alteration, however, this 
passes into the oxides valentinite, senarmontite, cervantite, 
stibiconite, etc., or into the combined sulphide and oxide known 


tJ. H. CoLiins, Mineralogical Magazine, Vol. IV., 1882, p. 115. 


SUPERFICIAL ALTERATION OF ORE DEPOSITS. 313 


as kermesite. Valentinite and senarmontite have the same 
chemical composition but differ in their crystalline forms. Native 
antimony sometimes occurs, and this also, by alteration, gives 
rise to the oxides. 

Alteration in bismuth deposits —The allied metal bismuth occurs 
most commonly as native bismuth, though the sulphide (bis- 
muthinite), the selenide (guanajuatite), the telluride (tetrady- 
mite), etc..also occur. Native bismuth, by alteration, forms the 
carbonate (bismutite) and probably also the oxide (bismite) and 
the silicate (eulytite). 

Alteration in mercury deposits—In the case of mercury the 
metal commonly occurs as the sulphide (cinnabar), though other 
mercury minerals also occur. By the alteration of cinnabar and 
some of the other mercury minerals, metallic mercury is set free 
and occurs as globules or filling cavities in the ore. 

Alteration in molybdenum deposits—Another case of surface 
alteration in metalliferous deposits is that seen in molybdenite. 
This mineral is the sulphide of the metal molybdenum, and often 
occurs in quartz or calcite veins in the crystalline rocks of parts 
of Canada, and in many ore deposits of the Rocky Mountains 
and elsewhere. By surface oxidation, molybdenite passes into a 
brilliant yellow oxide of molybdenum, commonly known as 
molybdite or molybdic ocher, which, in the Canadian region, 
occurs aS a powdery coating on the cleavage planes of the 
molybdenite. 

Alteration in other deposits —Superficial alteration like that 
already described in various deposits, occurs also in many others 
not yet mentioned, as in aluminum, nickel, cobalt, chromium, 
tungsten, and many rarer deposits, but the changes already 
described show the general features of the subject. It may be 
said, however, that one of the important ores of aluminum, known 
as bauxite, is probably derived from the alteration of feldspar 
under certain conditions ; and its source, therefore, is not alto- 
gether unlike that of the hydrous sesquioxide of\iron derived 
from the alteration of certain silicates. The conditions during 
formation, however, were probably quite different. 


314 LTE: fOORNAL OR (GLROLOGY. 


THE FORMATION OF HALOID COMPOUNDS IN ORE DEPOSITS 
IN ARID REGIONS. 

The formation of chlorides and other haloid compounds 
has already been mentioned as one of the phenomena of super- 
ficial alteration in ore deposits. As soluble chlorides and some- 
times other haloid compounds are common in surface waters, 
chlorides and the allied compounds are not at all uncommon as 
alteration products, especially in such cases as that of silver, 
where the chloride, bromide and iodide are insoluble compounds, 
and are not leached out. For this reason, chloride ores of 
silver are found to a greater or less extent in almost all silver 
districts in America, Europe, and elsewhere, but the occur- 
rence of such compounds in very large quantities in certain 
parts of North and South America deserves special explana- 
tion. 

Over a large part of the arid region of the west, lying between 
the Rocky Mountains and the Sierra Nevada, ores containing 
chloride of silver (cerargyrite ) are abundant,and sometimes the 
bromides and iodides also occur ; in fact, parts of this region are 
characterized by chloride ores. They are especially well devel- 
oped in parts of New Mexico, Arizona, Utah, Nevada and other 
states and territories, and it seems probable that their abundance 
can be traced to the effect of the peculiar climatic conditions 
which have prevailed in that region in late geologic times. 
Most of this arid country was once covered with numerous bodies 
of water, some of them of great size. In late geologic times, 
however, these began to dry up, until their waters no longer rose 
high enough to have outlets, and then, as a natural result, they 
became highly impregnated with salt and other saline matter. 
Finally, they became desiccated, leaving deposits of various 
earthy and saline materials in their old basins, and among the 
most common of these was common salt. It seems probable 
that the abundance of chloride ores is due to the action of 
this salt on the pre-existing ore deposits of the region, in the 
basins of the lakes, and that the smaller quantities of bromides 
and iodides were formed by a similar action of the soiuble 


SOPERPUCIAL hE LiRALTON, OF \OKRE DEPOSTLS: 315 


bromides and iodides in association with the salt. Such ores, in 
some of the mines that have gone to sufficient depths, have 
passed into various other silver compounds, such as the sulphide 
(argentite), argentiferous galena, etc., which represent the 
original condition of the ores. This transition proves the 
chlorides and other haloid compounds to be of only superficial — 
extent. 

This transition to haloid compounds is not confined to silver 
ores, for the basic chloride of copper (atacamite) occurs at 
Jerome in Arizona, and both chlorides and bromides of copper 
occur in the Bloody Tanks district west of Globe in Arizona, 
though here, as elsewhere in Arizona, the other copper minerals 
already mentioned, such as carbonates, sulphides, etc., form the 
bulk of the copper deposits. 

In parts of Mexico, Chile, and Peru, where saline materials 
have collected in a manner somewhat similar to that in the arid 
regions of the United States, the chloride of silver is one of 
the important ores mined, and it sometimes occurs intimately 
mixed with chloride of sodium, or common salt, forming the 
mineral huantajayite or the lechedor of the miners. The brom-- 
ides of silver are also abundant in Chile, and, in fact, at the . 
mines of Chanarcillo, a common ore is the double chloride 
and bromide known as embolite. Again, the atacamite, or. 
basic chloride of copper, from the Desert of Atacama is well 
known. 

It seems probable that this transformation of the silver and 
copper minerals did not necessarily occur exclusively while the 
deposits were covered by saline lakes, but may have occurred 
even more actively afterwards, when the surface waters were 
highly impregnated with chlorides from the residue left by the 
lakes, and when oxidation in the ore deposits was much more ° 
active than when they were covered by water. This seems all 
the more likely when we consider that the original silver and 
copper minerals probably had to be oxidized before they were 
converted to chlorides, etc. Of course the oxidation may have 
partly occurred before, or during, the existence of the lakes, but 


316 THE JOURNAL OF GEOLOGY. 


in many cases it probably also occurred after they were desic- 


cated.? 
SUMMARY. 


It will be seen from the above discussion that: 

(1) After the deposition of ore deposits and their subsequent 
exposure to surface influences, such as air, water and the mate- 
rials contained in it, changes of temperature, etc., chemical and 
physical alterations occur which cause a total change in the min- 
eralogical condition, and generally in the economic value, of the 
ore deposit. : 

(2) The process of this alteration is primarily one of oxida- 
tion and generally of hydration, and both of these actions may 
go on alone, but generally both have their effect on the same 

material. The other materials in solution in surface waters also 
react on the substances in the ore deposit, either before or after 
the oxidation of the latter, though generally after at least partial 
oxidation, and form various compounds different from those 
originally in the deposit. The difference, however, with few 
exceptions, is not in the metal or other base which forms the 
important feature of the deposit, but in the acidic portion or 
material representing this portion of the mineral. Thus, sulphide 
of copper may be altered to carbonate of copper, but the base 
remains the same. The action of surface influences is in rare 
cases one of reduction, which, however, often follows-a previous 
oxidation. The process of alteration also frequently causes a 
leaching of certain ingredients of the ore deposit, either with or 
without previous oxidation, as in the removal of iron pyrites, 
calcite, etc. It also sometimes renders a hitherto worthless 
material valuable by the introduction of a valuable constituent, 
as in the replacement of carbonate of lime by phosphate of lime. 
It also causes the concentration, by capillary action in soils, of 
certain deposits like nitre, etc. The compounds formed with 
different ore deposits vary with the ores affected and the sta- 

* Chlorides of other materials than silver and copper may also have been formed 


by a similar process, but the solubility of many metallic chlorides would prevent their 
being accumulated in any but very dry regions. 


SUPERFICIAL ALTERATION OF ORE DEPOSITS. Sul 


bility of the compounds formed by the action of the materials in 
the surface waters on the constituents of the ores. 

(@)) Mine physical effect of superficial alteration is generally 
to make the deposit more open an porous, to cause it to shrink, 
and, in some eases, to convert it to a loose material of the con- 
sistency of sand and clay. In some cases, however, especially 
where hydration is active, and expansion may be caused. 

(4) Superficial alteration extends downwards as far as sur- 
face influences are able to act, though generally alteration is not 
complete down to the possible limit. The depth of alteration 
depends on the topography of the region, the nature of the 
rocks, and on the climate. In glaciated regions, the glacial 
action has swept away the products of alteration, and sufficient 
time has not yet elapsed since then for alteration to have gone 
on to any great extent, but in many other regions the products 
of alteration have accumulated to considerable depths. The 
depth of alteration, under different conditions, varies from a frac- 
tion of a foot to 1,500 feet, or possibly more. 

(5) Superficial alteration is well illustrated in iron, man- 
ganese, copper, lead, zinc, silver, gold, tin, and many other 
deposits. For special descriptions see text. 

(6) The accumulation of soluble saline materials, like salt, 
on the surface has a very important effect in converting certain 
materials in underlying ore deposits to chlorides, etc. 

R. A. F. PENROSE, JR. 


S 2UDIES TORS GO Dinas: 


EROSION, TRANSPORTATION, AND SEDIMENTATION 
PERFORMED BY THE ATMOSPHERE. 


In dynamical geology there is one line of inquiry which has 
received, comparatively speaking, but little attention from Ameri- 
can geologists. Our text-books discuss in a thorough manner 
the work performed by water, and they also tell us much about 
the work of earthquakes, of volcanoes, and of glaciers. Some 
of these phenomena appear so striking as always to challenge 
our attention. Others are so common in their occurrence and so 
obvious that they suggest themselves to our study and to our 
reflection everywhere. The work performed by the winds in 
the atmosphere appears hardly to have received its due share of 
attention. The transportation of solid materials by the air is 
one of those subtle operations in nature, which are apt to escape 
our observation. The process is of an unobstrusive nature, and 
only in certain localities becomes at all obvious. There are, 
however, some scientists who have understood and urged the 
great importance and efficacy of aerial transportation in geologi- 
cal dynamics. Ehrenberg, Von Richthofen and Pumpelly will be 
remembered first in this connection. Blake, Gilbert, Hayden, 
N. H. Winchell, Chamberlin, Merrill, and others have described 
instances of erosion and transportation by the atmosphere. But 
it will be conceded, I think, that the subject has not received 
any general and searching attention from geological students in 
this country. This is the only excuse for presenting at this 
time a few considerations bearing on the topic. I take the lib- 
erty to state in a dogmatic way what appear to me to be some 
laws governing aerial erosion, transportation and sedimentation 
in general. It is not claimed that these statements contain 
much that is new in substance. 


As an agent of erosion air ts far less efficient than water. 
318 


EROSION PERFORMED BY THE ATMOSPHERE, 319 


The chief circumstance on which this inefficiency depends is 
the small weight of the air, which is only about g+, as heavy as 
water. Moving with the same velocity it will strike with a force 
only y+, as great as that with which water will strike. The 
effectiveness of the impact, however, or the striking force, 
increases as the square of the velocity and thus when the veloc- 
ity of the wind is 28 (—813=28) times greater than that of a 
current of water, the impinging force of the two currents is the 
same. Velocities 28 times greater than those of many rivers dre 
not uncommon in the air asmall distance above the ground. But 
the lightness of the air enables even a scanty vegetation to 
greatly slacken the speed in the currents immediately in contact 
with the ground. This slackening of the impinging current 
is apparently sufficient to effectually protect even loose soil 
from wind erosion under ordinary circumstances. Such is 
at least the case where the soil is moist and where the land 
is level. 

As an erosive agent, the atmosphere is at a disadvantage also 
in another respect. Lakes never erode their bottoms below the 
plane of wave action, and even in rivers erosion is greatest at the 
shores where this plane meets the land surface. Were it not for the 
wave action, the erosion by continental waters, as well as by the 
waters of the oceans, would be greatly reduced in its efficacy. 
In fact we generally look at that part of the surface of the earth 
which is under water, as being an area of deposition and sedi- 
mentation, and at the land above water and the coast lines alone, 
as being areas of erosion. Whatever be the height of the atmos- 
phere, it does not appear likely that its upper limit is a well 
defined plane with waves as on the sea. But evenif it be, this wave 
plane would be high above the most elevated point on the earth’s 
surface. There is, therefore, no plane of wave-erosion in the atmos- 
pheric sea. Such work of this kind as is performed by the air 
can only be compared with that which takes place in the ocean 
far below its plane of wave-action, and rather in its abysmal 
region. Evidently this is not very great, if of any consequence 
at all. 


320 THE JOURNAL OF GEOLOGY. 


Wind erosion becomes geologically important only in certain local- 
ties, and the conditions favoring it are a ary climate and a topography 
of abrupt and broken relefs. 

On plains where the ground is dry and vegetation scanty or 
absent, ordinary strong winds are apt to slowly wear into the 
soil, where the roots of plants do not protect it. If such soil 
contains sand which is too coarse to be lifted up and carried 
away, dunes are formed, and the uneven topography thus devel- 
oped still more favors wind erosion; for it is evident that the slopes 
of the dunes will be struck with greater force than the even sur- 
face of a level plain. In such places the sand grains are tritura- 
ted and worn, and the abraded material is promptly removed. 
It is also evident that where a country is traversed by vertical 
escarpments and cliffs, and steep slopes, strong eddies are set up 
as the wind strikes these reliefs. Where the rocks are of fine 
materials and but little indurated, like most of the Mesozoic and 
Cenozoic beds of the west, it would be singular if such eddies 
did not erode the bare surfaces of their outcrops. It does not 
appear practicable to estimate separately the erosion produced 
by impact of the air alone, and the abrasion produced by the 
materials carried. The ratio between the two will, of course, 
vary with the quantity of the load. Where this is considerable, 
abrasion is no doubt proportionally greater than in water, for the 
speed of the impinging particles is here much higher, and their 
striking force consequently greater. Occasionally this circum- 
stance greatly intensifies aerial erosion and produces a natural 
sand-blast, which is very effective in its action on solid rock. 
That such abrasion becomes appreciable and important along the 
escarpments of ‘‘mesas”’ in dry regions appears not to admit of 
a doubt. In such places the driven sand may sometimes be felt 
smiting the exposed skin of the traveler. 

The speed of the wind being lowest near the surface of the ground, 
materials must by some means be lifted through this zone of low veloc- 
ity in order to be transported any considerable distance by the atmos- 
phere. 

According to some observations made by Stevenson, the aver- 


EROSION PERFORMED BY THE ATMOSPHERE. 321 


age velocity of the wind increases very fast and apparently not 
according to any definite law upwards for the first fifteen feet 
above the ground. Above this height it increases as the bisected 
chords of parabolas having their vertices in a horizontal line 72 
feet below the surface. The parameters of these parabolas 
increase directly in the ratio of the squares of the velocities of 
the different winds. With a velocity of ten miles per hour at an 
elevation of fifty feet above the ground there will then be a veloc- 
ity of about one hundred miles per hour one mile above the 
ground, but of less than one mile per hour near the surface. 
Observations made on the movements of clouds verify these 
calculations as to high velocities some distance up in the atmos- 
phere. Whatever is to be transported any great distance must 
be lifted up to some considerable height above the surface of the 
earth, where the winds attain high velocities. 

Over level plains, under ordinary circumstances, the condi- 
tions seem to be unfavorable for effecting any such upward 
transference, and little or no removal of material is apt to take 
place. But when a strong wind runs up against a vertical cliff, 
such as are seen in the bad lands or in the country of the pla- 
teaus and ‘“‘mesas,” eddies are no doubt set up which rise high 
above these vertical reliefs. A short valley or a reéntrant exca- 
vation in such a cliff will gather the wind and start it with 
increased force obliquely upwards, as it enters from the open end. 
In such a mobile element as the atmosphere an eddy like this 
may fise a considerable distance. No less effective in this 
respect are the whirlwinds in arid regions, which have been 
described by nearly every traveler in such countries." During 
the warm part of the day these can be seen, it is said, at almost 
any time in some direction of the horizon. They often rise toa 
ereat height, carrying with them the loose materials of the desic- 
cated soil and giving them up to the incessant and steady run of 
the winds above. 

The explosive outburst of a volcano similarly launches enor- 
mous quantities of minute fragments of pumice on the currents 


1 Gro. P. MERRILL, Engineering Magazine, Vol. I1., p. 599 é7 seg. 


322 THE JOURNAL OF GEOLOGY. 


of the atmospheric ocean, throwing them upwards sometimes 
over 10,000 feet. Small quantities of incombustible matter are 
raised to the horizon of translation above by heated currents of 
air from chimneys and fires, and perhaps still smaller quantities 
by birds and other animals of flight. 

Aside from these instances there are no important means by 
which the atmosphere is loaded, and for this reason, among 
others, its importance as a geological agent issmall. The load to 
be carried must be raised before it is borne away. In water the 
contrary is almost always the case. The material to be trans- 
ported is supplied at the water’s surface and from the start to 
the end of the transport the sediments are allowed to slowly 
sink. They are transported forward and downward; in the 
atmosphere they must be transported first upward, and then 
forward. 

To be subject to transportation by the atmosphere, rock matertals 
must be finely comminuted, the average largest size of quartz particles 
that can be sustained in the air by ordinary strong winds being about 
I mm. in diameter. 

This statement is based on a number of measurements, which 
have been made on sand and dust transported by the air. Among 
these are measurements of dust and sand raised by the wind from 
roads and streets in dry weather; of dust which fell on the ground 
at Kansas City, Mo., after a severe west wind on the plains; of 
dust collected after dry storms on the window-sills in residences 
in the central part of Kansas; of sand taken in crevices and cor- 
ners in railroad cars in various parts of the country. It agrees 
with measurements made on volcanic dust known to have been 
carried several hundred miles in the atmosphere. Corroborating 
results have also been obtained by some simple experiments. 
- The constituent materials of a coarse loam were separated into 
groups of different grades of fineness. These separations were 
thrown into the air and observations made on their behavior. 
- The velocity of the wind was about eight miles per hour, and 
the observations may be tabulated as follows: 


EROSION PERFORMED BY THE ATMOSPHERE. 323 


A verage Behavior of the particles when thrown 
diameter of into the air 
particles. 


.75 mm. Described a path diverging about 10° from a vertical line. 
.37 mm. Described a path diverging about 45° from a vertical line. 
.18 mm. Described a path diverging but a few degrees from a horizontal 
line, were blown upward by eddies. 
.o8 mm. Could scarcely be noticed to settle in transport. 
.o4 mm. Apparently completely borne up by the wind. 
.007 mm. Completely borne up by the wind. 
.0ol mm. Completely borne up by the wind. 


It is hardly necessary to add that the average size of the largest 
particles carried varies greatly with the velocity of the wind. 
Sand grains will occasionally be found to have been thus carried, 
which have a diameter many times larger than the average maxi- 
mum here stated. The presence of such large grains can readily 
be accounted for by the chances for becoming entangled in spe- 
cifically lighter objects, such as fragments of leaves and other 
vegetation, and thus to be carried by them. It will be under- 
stood, also, that the statement made above does not apply to 
that phase of wind-transportation which takes place on the sur- 
face of a sand-dune, where the sand is as if rolled forwards, nor 
to that in the very lowest part of the atmosphere generally, 
where materials are thrown forwards short distances at a time by 
eddies due to the contact of the atmosphere with the more or 
less irregular surface of the land. 


The capacity of the atmosphere for transporting particles of quartz 
below the size of .I mm. in diameter, 1s very great. 


Disregarding the occasional transference of matter by vol- 
canic forces and by living organisms, there are only three prin- 
cipal agents known to be at work removing materials from place 
to place on the surface of the globe: lineseyane water, ice, and 
air. It is believed that, with the above limitation as to the fine- 
ness of the material, the transporting power of the atmosphere, 
as compared with that of water and ice, is very great. The trans- 
porting capacity of the water in our continental rivers is better 
known than that of glaciers or of ice fields, and it makes our best 


324 THE JOURNAL OF GEOLOGY. 


standard of comparison. Let us take, for instance, the work 
of transportation which is performed by the Mississippi river. 

The efficiency of any transporting current is determined by 
three factors, viz) (1) thevarealot its) tramsverse) section, §(2)) 
the velocity of its motion, and (3) its capacity for holding a 
load. In the case of the Mississippi basin we may say that the 
products of disintegration and erosion within its boundaries may | 
be removed by principally two agents, water and air. What is 
removed by water all passes out through the channel of the 
lower Mississippi. The size of this current in transverse section 
is less than) =~, Oba Square, mille; itris evident thatrallljeme 
materials removed by this river from its great basin, whether 
taken from the Rocky mountains or from the Appalachian high- 
lands, must pass through the same narrow circumscribed limits 
‘of ;1, of a square mile.in the lower course of the river. Now, 
the atmosphere may also be regarded as a current. The width 
of this current will be the average width of the entire drainage 
basin of the Mississippi, and in its height this current equals the 
height of the atmosphere. Taking this to be ten miles, which 
cannot very well be too much, and taking the average width of 
the Mississippi basin as one thousand miles—it is at least one 
hundred miles more—the transverse section of the atmospheric 
current will be ten thousand square miles. The ratio of the 
sizes of these two currents as shown in their sections is thus 
I : 1,000,000, 2. ¢., the cross section of the Mississippi current is 
TOO 0y of that of the atmosphere. If velocity and capacity 
for carrying a load were the same in both currents, the relative 
transporting power of the greater one would be 1,000,000 times 
that of the smaller. 

In respect to velocity the Mississippi is also less effective in 
its work than the atmosphere above it. The average velocity of 
the wind over the interior basin is not less than eight miles per 
hour, while the average velocity of the lower Mississippi is about 
.7 mile per hour. The ratio of the velocities is therefore repre- 
sented by the fraction ,4, which is a little less than ~). lt, 
therefore, the two currents were equal as to their cross sec- 


EROSION PERFORMED BY THE ATMOSPHERE. 325 


tions and as to their capacity for sustaining a load, the current 
with the greater velocity would be able to remove ten units of 
sediments, while the slower current would remove one. Multi- 
plying the fraction expressing the ratios between the cross sec- 
tions of the two currents (;op}o07) by the fraction expressing 
the ratio between their velocities (15), we obtain a fraction 
which expresses their relative carrying power, if their capacities 
for sustaining a load were the same. This fraction is zgqgqyqa0- 
If every cubic foot of air in the atmosphere held in suspen- 
sion as much of sediments as every cubic foot of water in the 
Mississippi, then the atmosphere would have the power to 
transport in a given time ten million times the quantity of mate- 
rial transported in the same time by the Mississippi river. 

With regard to the capacity for holding solid particles in 
suspension the air is, however, greatly inferior to water. It is 
evident that the load which can be carried by the air at ordinary 
and even in high velocities, is a great deal smaller than that 
which can be carried by water. The capacity in this respect of 
any current depends on chiefly three factors: (1) the density 
of the medium, (2) its velocity, and (3) its viscosity. As to 
the comparative densities of the two fluids, the air is only ,+, 
times as heavy as water. Another circumstance also comes into 
consideration. When the particles of a material like quartz are 
suspended in water, they lose about $4 of their weight in the air, 
and the force with which they make their way downwards 
through the water is thus reduced to $8 of what it would be in 
the air. This still more increases the relative carrying power of 
water making it 1321 times as great as that of the air (813(26)= 
321) a Oni eaccountor thie greater average velocity of the 
atmosphere and also by reason of the consequent greater magni- 
tude of its convection currents, this again has the advantage over 
water. But exactly to what extent these considerations affect 
the comparison, data are not at hand to determine. It would 
appear that the advantage connected with these greater convec- 
tion currents more than outweighs the disadvantage due to the 
lesser viscosity of air, when compared with water. At such low 


326 BE VOOKINALNOFAGEOLROGN. 


velocities and temperatures this difference in viscosity can per- 
haps be altogether disregarded. The relative power of the 
atmosphere to sustain a load of fine sediments would, therefore, 
appear to be no more than, say 37>: of that of river water. 
But to be certain that this estimate shall not be too high, let us 


make the fraction ¢ of this value and call it 75175. This means 
that if a cubic foot of water, e. g., in the Mississippi, will hold in 
suspension 15.48 grams of solid particles’, then the atmosphere 
above it can hold in the same manner in a cubic foot zpiop of 
this quantity, or about .0015 gram. It will be remembered that 
this is true only for material of a certain coarseness. If it is too 
coarse, the atmosphere cannot hold it at all; while if it is very 
fine, considerably more can no doubt be sustained. In order to 
ascertain approximately the effect of the variation of the size of 
‘the particles on the quantity of materials which can be thus sus- 
pended in the air, and also to make sure that the above estimate 
of the total load of sediments which can be sustained is not too 
high, some simple experiments have been made. These con- 
sisted in introducing dust of varied degrees of coarseness into a 
receiver, and then keeping the air in the receiver in constant agi- 
tation at a velocity of about five miles per hour. A certain 
quantity of dust would in this manner be kept floating in the cir- 
culating air, and this quantity was found to vary with the nature 
of the material introduced. The results may be tabulated as 


follows: 
Average diameter of Quantity sustained in one cubic foot of air 
particles. agitated to an average velocity 
of 5 mt. per hour. 
FOSuenmmials - - - = .020 gram. 
ov igahog, 9 = - = = On 
.007 mm. - - - - RET Oy ames 
.ool mm. (and below) - - (05 3ipeuue 


This apparently amply justifies the above estimate as to the 
quantity of dust which can be sustained in a certain bulk of 
atmospheric air. It is not supposed that the table gives exact 
determinations for the different materials, for the conditions of 

* Humphreys and Abbott. 


EROSION PERFORMED BY THE ATMOSPHERE. 327 


the experiment are of the most delicate kind and a slight change 
in the velocity will cause a considerable variation in the quantity 
of the load. 

If then the ratio of the sections of the two currents is 
zostoss the ratio of their velocities 4, and the ratio of their 
loads per unit of bulk of the two media is *°;*°, the ratio of 
their respective transporting powers is as the products of these 
fractions, or ;;/yy- This is the same as to say, that if a cubic 
foot of air can hold in suspension ;ptpy of the quantity of fine 
dust held in the same way by the water in the Mississippi river, 
and if the velocity of the winds in the atmosphere is on the aver- 
age not less than ten times as great as the rapidity of the current 
in the river, and if the area of a vertical section of the atmos- 
phere over the valley is 1,000,000 times as large as the area of a 
cross section of the lower stream,—then the capacity of the 
atmosphere to transport dust is 1,000 times as great as that of 
the river. 

Atmospheric currents being loaded, mostly, only to the extent of an 
insignificant fraction of their capacity, their sediments will be better 
sorted than deposits in water-currents, which are more often loaded to 
their full capacity. 

It is evident that the greater the load carried by any current, 
the shorter is the average distance from particle to particle while 
in transport. This increases the chances for the particles to be 
affected by each others’ movements through the medium and 
thus for coming together to form clusters. This process, which 
has been called flocculation, causes more rapid sedimentation, 
for such a cluster of particles will fall faster through the medium 
than will the separate grains of which it is composed. Floccula- 
tion takes place among particles of all sizes, and small particles 
which would otherwise be retained in the supporting medium, 
will easily settle when collected into these clusters. Sediments 
which have been formed under such circumstances will hence 
contain a proportionally greater quantity of fine material than if 
flocculation had not taken place. But flocculation increases with 
the quantity of the load, and since the load of the atmosphere is 


328 THE JOURNAL OF GEOLOGY: 


at least 1,000 times (under ordinary circumstances perhaps nearer 
100,000 times) less per unit of bulk of the carrier than in most 
waters where sedimentation occurs, it is likely true that floccula- 
tion in aerial sediments is not as great as that which takes place 
in aqueous sediments. Thus the finest materials carried by the 
air are not deposited in so great a proportion with the coarse 
material, as they would be if the atmosphere carried a greater 
load. The finest sediments, say particles below .002 mm. in 
diameter, settle only during extreme calms, if not first caused to 
gather in flocculi. This extremely fine material is retained by 
the atmosphere and must be carried everywhere over the entire 
surface of the globe, and must also be deposited everywhere, but 
in such small quantities as not to be noticeable. No small part 
of it, it may be surmised, is carried from the land and precipi- 
tated into the sea. But the coarser sediments, say particles 
between .002 and .I mm. in diameter, are less easily retained in 
the air and therefore occasionally deposited in favorable localities 
in such quantities as to become an object of geological signifi- 
cance. It is maintained that in these deposits from the atmos- 
phere there should be a scarcity of the finest materials. 

It should be remembered, however, that there are great 
differences in the prevailing wind velocities and that this circum- 
stance will naturally bring together materials ranging through 
great differences in coarseness. It has lately been shown* that 
such differences are great, even within the limits of a minute of 
time. As aresult there will be a chance for a considerable range 
in size of particles composing the bulk of any aerial sediment, a 
range which it is believed might be expressed for the diameters 
of such particles by the numbers 1 and 100. Of course the 
range of the extremes will be much greater. 

Deposition of dust will take place where wind is caused to slacken 
ats speed. ‘ 

This is so self-evident that it appears superfluous to mention 
it.. It may be presumed that such a slackening will take place 
over continental basins, where the general direction of the wind’s 

1S. P. LANGLEY: Internal Work of the Wind. 


EROSION PERFORMED BY THE ATMOSPHERE. 329 


progress is transverse to the bounding highlands. It may also 
be presumed that the wind retards its velocity, when going down 
an inclined plane. The greater depth of the atmospheric ocean 
in these instances ought to have the same influence on the gen- 
eral current as the widening or deepening of a river channel. If 
this be the case with extensive continental depressions, valleys 
of rivers and smaller depressions of the earth’s surface ought to 
produce somewhat similar effects in retarding the passing wind 
and inducing it to give up a part of the dust it may happen to 
carry along. On the other hand, when the wind passes over 
land covered by a growth of timber or only tall grass, its lowest 
part will be held comparatively still and will drop its load. Did 
the same air remain among the vegetation all the time this 
unloading process would stop with the first deposit, but as the 
eddies no doubt keep up a slow but constant exchange with the 
air above, the accumulation continues as long as there is any 
aust tert: 

Several important deductions can be drawn from the forego- 
ing considerations. 

The velocities in the atmosphere being so much greater than 
those obtaining in rivers, lakes, and seas, the distances over which 
materials may be transported in it will be correspondingly 
greater. In the sea sediments are carried'out 200 miles and 
even farther. In the atmosphere, where the velocities often are 
100 times greater than those in the sea, dust may, no doubt, be 
transferred a distance of several hundreds, if not a few thousands 
of miles. The very finest particles may be borne round the 
earth, as shown by the dust of Krakatoa, or may, indeed, circle 
about it for some time. 

The greater depth of the aerial ocean renders it but little 
dependent in its movements on smaller elevations of the land. 
In a sea five miles deep an elevation of the bottom 8,000 feet 
high would interpose no serious obstacle to a general forward 
movement of the whole body of the fluid. Few of our mountain . 
ranges exceed this height, and it would not seem impossible, 
therefore, that dust in some notable quantities should be carried 


330 LTE, fOOKINAL VOT NG OL OGM. 


across a mountain range, provided there be a favorable current 
in the upper part of the atmosphere. 

While the conditions requisite for much aerial erosion are 
limited to rather small areas on the land of the globe, there can 
be little doubt that deposition is much more general and wide- 
spread. For dust is carried everywhere. And if it be conceded 
that the atmosphere is never entirely free from dust, it follows 
that sedimentation occurs wherever and whenever there is a com- 
parative calm. In places in the ocean, where sedimentation is 
known to be very slow, atmospheric dust may be supposed to 
form an appreciable part of the deposits. 

The areas of deposition being much greater than the areas of 
erosion, it is evident the accumulations of atmospheric sediments 
as a rule are insignificant, only exceptionally exceeding on the 
land the secular erosion by water, and therefore accumulating 
only in such exceptional cases. 

From a dynamical point of view the wind-theory would 
appear to furnish an adequate explanation of the occurrence of 
the loess in the Mississippi valley, at least as to most of its 
phases. The recent denudation of the western plains, of the 
bad lands, and of the Cordilleran plateau is extensive enough to 
furnish the materials many times over. The different rocks in 
these regions and the changeability of the atmospheric currents 
would combine to bring together and thoroughly mix a variety 
of materials, like those of which the loess is composed. The 
winds would naturally distribute over wide areas the heterogene- 
ous but uniform mixture thus produced. When not taken close 
to exposures of other materials ninety-nine per cent, by weight, 
of the loess is composed of particles below the size of .1 mm. 
and it contains only a small proportion of the finest materials 
common in clays and residuary earths, just as must bes themecase 
in an atmospheric sediment. In the United States, lying in the 
zone of westerly winds, we find the loess in the continental basin 
east of the arid regions. It is best developed along the western- 
most north-and-south drainage valley, that of the Missouri-Mis- 
SiSSippi river. Almost everywhere it is heaviest nearest the. 


EROSION PERFORMED BY THE ATMOSPHERE. 331 


watercourses. In northeastern Iowa its distribution shows such 
remarkable coincidences with the distribution of the primeval 
forests, as to only leave the uncertainty whether the loess is the 
cause of the growing of the forest or the forest the cause of the 
accumulation of the loess.” 


J. A. UDDEN. 


AUGUSTANA COLLEGE, 
Rock Island, Il. 


t See Pl. XXII and XLIV, Eleventh An. Rep. U.S. Geol. Survey. MCGEE. 


2 DIMORI AES. 


THE circular of information regarding the Sixth International 
Congress of Geologists, to be held at Zurich from August 29th 
to September 2d, presents a most inviting programme of excur- 
sions, which may be taken by members of the Congress, in the 
picturesque and geologically famous regions of the Swiss Alps 
and the neighboring Jura Mountains. It is proposed to organize 
two groups of excursions conducted by geologists, many of whom 
have devoted the better part of their lives to the investigation of 
the country visited. The first group will be offered immediately 
before the meeting of the Congress, and is so arranged that those 
participating in them will arrive at Zurich a day or two before the 
opening of the Congress. These excursions will be devoted to 
various portions of the Jura Mountains. They will be organized 
in different towns, where those intending to take the excursions 
are to join the conductors of the parties. The second group of 
excursions take place immediately after the Congress adjourns, 
and will start from Zurich on September 3d, and will traverse the 
Alps by various routes, terminating at Lugano, about September 
16th, where the Congress will be formally closed. There will be 
two classes of excursions. One class will be made on foot, in 
order that the geology of the country may be more carefully 
examined. The other will be by means of conveyances. The 
pedestrian excursions will necessarily be open to a limited number 
of persons, and warning is served that a certain amount of quasi- 
military discipline will be required by the leader, from which 
appeal may be made to the whole body of participants. The 
expediency of such a regulation will be apparent to all who have 
attempted to conduct similar tours. The second class of excur- 
sions will make use of railways, steamboats and carriages, and 
will aim to reduce to a minimum the distance to be gone over on 

332 


EDITORIALS. 353 


foot. The management of the details of transportation of these 
excursions will be entrusted to the agency of Messrs. Ruffieux 
and Ruchonnet at Lausanne ; their scientific direction will be 
undertaken by Professor Renevier and Professor Golliez, of the 
University of Lausanne, The first excursion of this sort will 
start from Geneva, where those participating in it will assemble 
on the 15th of August, and will spend thirteen days visiting 
localities in or near the Jura, including the environs of Geneva, 
Lausanne, Neuchatel, Bale, and the Falls of the Rhine. The 
second of these ‘‘ voyages en zig-zag” will start from Zurich 
on September 3d, and will spend thirteen days in the most 
delightful parts of the Alps, visiting, among other points, the 
Rigi, St. Gothard, the Lake of the Four Cantons, the Jungfrau, 
the Matterhorn, and the Italian lakes. The cost of the first 
excursion is to be $60, and of the second $80. 

Of the pedestrian tours, five are to take place before the 
meeting at Zurich. One, under the direction of Professor 
Schardt, of Montreux, will devote six days to the French Jura 
in the neighborhood of Geneva, the rendezvous being at Geneva, 
August 21st. The second, conducted by Professor Jaccard, of 
Neuchatel, will spend five days in the Jura of Vaudois and in the 
neighborhood of Neuchatel. The rendezvous is to be at Pont- 
arlier, August 22d. The third excursion, in charge of M. Rollier, 
of Bienne, will spend six days in the Bernese Jura, the rendez- 
vous at Delémont, August 21st. The fourth, under the direction 
of Professor C. Schmidt, of Bale, will devote five days to the 
vicinity of Bale and the country east of the Argovian Jura ; the 
rendezvous at Bale, August 21st. The fifth excursion, under 
Professor Mihlberg, of Aarau, will spend five days in the 
Argovian Jura and in the neighborhood of Soleure. The rendez- 
vous will be at Aarau, August 23d. 

There will be four pedestrian tours after the meeting of the 
Congress, one under the leadership of Professor Heim, of Zurich, 
who will conduct a party over the eastern Alps of Switzerland 
from St. Gallen to Tessin, studying the compressed folds in the 
Santis, and crossing the great Glarner double fold. Professor C. 


334 THE JOURNAL OF GEOLOGY. 


Schmidt will conduct a party over the central Alps from Zurich 
to Lugano, visiting the “ cliffs” of the Mythen and following the 
Gothard route across the crystalline axis of the Alps. Professor 
Baltzer, of Bern, will conduct another party over the Bernese 
Alps, from Lucerne to Tessin, examining the intricately plicated 
strata of the Gstellihorn, passing over the Grimsel and visiting 
the glaciers of the Unteraar and the Rhéne. Professor Schardt 
will lead a party over the western Swiss Alps from Bulle, study- 
ing the complicated structure of the Alps of Freiburg, and cross- 
ing the Téte-Noire to Domo-d’ Ossola. These excursions will 
furnish foreign geologists the best possible opportunity of 
becoming acquainted with the complex structure and widespread 
metamorphism which have become classic through the untiring 
energy and intelligent investigation of the Swiss Geologists. It 
goes without saying that all who can find the time and means at 
their command will avail themselves of these exceptional oppor- 
tunities, and that the Sixth International Congress of Geologists 
will surpass its predecessors both in the number of members 
attending and in the benefits derived from the meeting. 
isda 


REVIEWS. 


Geological Survey of Georgia: The Paleozoic Group: The Geol- 
ogy of Ten Counties of Northwestern Georgia, and Re- 
sources. By J. W., Swaine, Va Wl5 lei. ID, CAS, (UG, aie! 
A.), State Geologist. Published by Authority. Atlanta, 
Ga. Geo. W. Harrison, State Printer, 1893. 


The state of Georgia has been somewhat unfortunate in the matter 
of Geological Surveys. That under the direction of Dr. George Lit- 
tle was discontinued before the publication of any extended report 
upon the work accomplished, and thus the results of a number of 
years of field work by competent geologists were lost to the state. The 
survey under Dr. Spencer was from the first heavily handicapped by 
the action of the Advisory Board in appointing the assistants without 
consultation with the State Geologist. It seems probable that this 
action of the Board will have the result of causing the loss to the state 
of all the work of the assistants so appointed.. It is very much to be 
hoped that the Advisory Board will profit by past experience, and 
under the new organization will leave the choice of his assistants to 
the State Geologist, Professor Yeates, who is the successor of Dr. 
Spencer in this important position. Under no other conditions could 
a geologist with any justice be held responsible for the conduct and 
results of a survey. 

The present volume records the work of Dr. Spencer in the Paleo- 
zoic terrane of Georgia, and a previously published report has dealt 
with the Tertiary and newer formations of the southern part of the 
state. 

In chapter I, there is a general sketch of the geological structure 
of northwestern Georgia, in which are discussed in general terms, and 
in non-technical language, the formation and destruction of rocks; 
the effects of terrestrial movements on the growth of strata; the dis- 
turbances and dislocations of the original beds; the origin of valleys. 
In chapter II, the formations of northwestern Georgia are given in 
tabular form, with their equivalents in other states; in general the 
names first proposed by Dr. Safford for Tennessee find acceptance in 

835 


336 TELE JlOUKNALVORNGEOEOGWV: 


this report, as they must with all who have to do with the Paleozoic 
formations of the states adjacent to Tennessee, for the descriptions 
and classifications of Dr. Safford are remarkably true to nature. 
Chapters III to VI inclusive are devoted to a general description of 
the lithological and other characters of the different formations 
which make up the area under consideration in Georgia. ‘The Ocoee 
group, which Dr. Safford places at the base of the Cambrian in Ten- 
nessee, or beneath the oldest of the fossiliferous strata, is mentioned 
by Dr. Spencer, but he does not enter into its detailed description. 
This group of semi-crystalline slates, often designated as hydro-mica 
schists, talcoid schists, and formerly as talcose schists, and which bears 
the greater part of the auriferous quartz veins in Georgia and Alabama, 
is extremely difficult to assign to its proper place in the series, in Ala- 
bama at least, for we find in the southeastern part of the Alabama Paleo- 
zoic terrane, some of the Knox or Montevallo shales slightly altered 
into partially crystalline slates, which we have not yet been able to 
discriminate from the unquestioned Ocoee. It has therefore seemed 
to us at least possible that the Alabama representatives of the Ocoee of 
Tennessee may be, in part at least, altered Cambrian shales. In chap- 
ter VIII the river alluviums and other formations later than the Car- 
boniferous are mentioned, and it is interesting to find that remnants 
of the Lafayette, in the form of pebbles and red loam, are to be found 
in many places in the Coosa Basin at elevations of 100 to 150 feet 
above the present level of the waters in those regions. These same 
beds have been traced by the Alabama survey up the Coosa valley to 
the Georgia line, and they are also to be found extending from the 
west, for a good many miles within the Alabama line along the Ten- 
nessee river. 

In chapter IX, dealing with the general physical features of the 
region, Dr. Spencer directs attention to the ancient character of the 
streams, and concludes that they long ago reached their base level of 
erosion, and have since been engaged in widening their valleys. In 

comparatively modern times (Lafayette), there has been a depression 
which has allowed the deposition of pebbles and loams at altitudes 80 
to 150 feet above the present stream level, and of course a still more 
recent movement of elevation which has brought the streams to their 
present position. Probably the most striking memorial of these move- 
ments is to be found in the “ flatwoods” of the Coosa Valley. This 
chapter is illustrated by a number of sections. Chapters X to XX 


REVIEWS. I Bao? 


inclusive, are devoted to the detailed description of the local geology 
of each of the counties embraced in this region. 

Part II (chapters X XI—XL inclusive) deals with the Economic Re- 
sources of the Paleozoic group, which are limonite, hematite, manga- 
nese ores, beauxite, coal, limestones, sandstones, and clays. The mode 
of occurrence of these materials, their distribution both geographical 
and geological, their analyses, etc., are shown forth in sufficient detail, 
and a commendable feature of Dr. Spencer’s treatment is found in the 
explanations and suggestions as to the origin of these various ores, 
expressed in terms which are easy of comprehension even by those 
who have not had any special geological or chemical training. In this 
way the book has a direct educational value apart from the great amount 
of information as to local occurrences which it contains. The chapter 
on beauxite is of special interest, because of recent developments in 
the mining and shipping of this valuable substance from the Georgia 
and Alabama mines. The occurrence and general character of the ore 
in the two states are identical, in fact the ores belong practically to a 
continuous deposit, in close connection with the strata of the Knox 
Dolomite. On account of competition with the foreign beauxites, only 
the higher grades of the ore. containing from 55 per cent. and upwards 
of alumina, are shipped, and by far the greater part of this goes to the 
making of alum. This seems a wanton waste, since the inferior grades 
would answer for alum, and the higher grades should be reserved for 
the manufacture of the metal. 

The coal of Georgia is confined to an area of about 200 square 
miles on the plateaus of Sand and Lookout Mountains. It is furnished 
almost entirely by two or three seams lying between the Upper and 
Lower Conglomerates near the base of the Coal Measures, as is the 
case also in Tennessee and the Plateau region of Alabama. In all this 
territory, these seams and the strata by which they are separated, are 
exceedingly variable in thickness. The most widely distributed of 
these is the Castle Rock seam just below the Upper Conglomerate 
(Main Etna and Cliff seams of Alabama and Tennessee). In Georgia 
the Dade seam, some 30 feet or more below the preceding, appears 
to be more extensively worked, and, in the sections given, of greater 
average thickness. This seam also has been worked in Alabama, where 
it is known as the Eureka seam. Still below this in all the states men- 
tioned is another seam of great importance locally, the Red Ash seam. 

In one locality, Round Mountain, which rises above the Lookout 


338 THE JOURNAL OF GEOLOGY. 


Table land as a prominent eminence, an important seam is described 
by Dr. Spencer, which lies many feet higher up in the measures, and 
which so far as we know does not occur in that part of Lookout Moun- 
tain that extends into Alabama. 

The clays described are of severai kinds, (1) the kaolin-like clays, 
(2) the residual clays from the decomposition of limestones and cal- 
careous shales, (3) the clays formed from the disintegration of shales, 
and (4) the alluvial clays. The first variety occurs in “ horses” or in 
sheets or pockets in the residual earths from the decomposition of the 
strata of the Knox Dolomite and Fort Payne series. These are often 
quite pure and white, and have nearly the theoretical composition of 
kaolin. Although they occur in the residual matters they are not, 
according to Dr. Spencer, zesedua of the limestones, but are derived 
from the rocks of the metamorphic series. 

The residual clays produce sometimes fairly good brick, but they 
are generally too rich in fusible materials to make fine products. Of 
greatest promise are the clays derived from the disintegration of shales 
and slates, some of which have given beautiful vitrified brick, such as 
would probably be well suited to serve as paving brick. The alluvial 
clays, especially such as belong to the Second Bottom deposits, in 
Georgia as well as in Alabama and Mississippi, furnish by far the 
greater part of the material for the manufacture of ordinary building 
brick, and it is of interest to note that the best quality of building 
brick along the whole Appalachian region is made from deposits of 
this character. 

In chapters XL and XLI we have a plea for better roads, with 
numerous illustrations of country roads in Europe and America, which 
emphasize sufficiently well the contrast between good roads and bad 
ones. ‘This is a seasonable chapter in view of the great interest now 
being awakened in the subject of better roads throughout the southern 
states. 

Part III, chapters XLII to XLIV, is devoted to the discussion of 
the origin and characteristics of the soils derived from the various 
Paleozoic formations, and the composition of these soils is shown also 
by a number of chemical analyses. 

An appendix containing acknowledgments and an account of the 
progress of the Survey, a classified table of contents and a full index 
conclude the volume. ‘The base of the map has been compiled chiefly 
from the topographic sheets of the U. S. Geological Survey, and in the 


REVIEWS. 339 


mapping of the geological formations, Dr. Spencer acknowledges the 
valuable aid which he has had from the previous work of Dr. C. W. 
Hayes in this territory. The map shows in a very clear and satisfac- 
tory manner the areal distribution of the formations. We cannot, 
however, speak so much in praise of the cross sections, in which the 
vertical scale is so greatly exaggerated as to be quite misleading. 

We consider this the most important of the official documents yet 
issued by the State of Georgia, and it is to be regretted that during 
his term of office Dr. Spencer did not have that complete control of 
the Survey that would have insured the publication of other reports of 
equal importance, especially one on the Crystalline Schists of the state. 

By. A. SMITH. 


Annual: Report of the Geological Survey of Arkansas for 1890; 
J. C. BRANNER, State Geologist ; Volume IV., Marbles and 
Other Limestones, by TY. C. Hopxins, 8vo., 443 pp., illus- 
trated by cuts and plates, and accompanied by an atlas con- 
taining six sheets. 


Tuis volume is the latest of the series of volumes published by the 
Geological Survey of Arkansas. It is separated into three divisions, 
which are sub-divided into twenty-eight chapters. The first division is 
the introductory chapter on the “General Description of the Marble 
Area.” After this comes Part I., which treats of limestones, including 
the following topics: ‘Composition and Origin of Limestone,” 
“Varieties of Limestone,” “Geologic and Geographic Distribution 
of Limestones,” “Limestone as a Building Stone,” “ Miscellaneous 
Uses of Limestone,” ‘“‘The Carboniferous Limestones of North Arkan- 
sas,” “The Silurian Limestones of North Arkansas,” ‘Carboniferous 
Limestones South of the Boston Mountains,” and ‘The Lime Indus- 
try of Arkansas.” 

Part II. treats of marbles, including the following topics: ‘The 
Origin and Uses of Marbles,’ ‘Marble in the United States,” 
“Marble in Other Countries,’ ‘Marbles of Arkansas,” ‘St. Clair 
Marblew2 1 ihe Distribution of the St Clair Marble; ~ St.) joe 
Marble,” “Distribution of the St. Joe Marble,” ‘Other Marbles found 
in Arkansas,” “Quarrying, and Cutting, Dressing and Polishing Mar- 
ble.” In addition to this there is an appendix treating of the “ Faults 
of the Marble Area of Northern Arkansas.” Like many of the other 


- 


340 THE JOURNAL OF GEOLOGY. 


reports of the Arkansas Survey, this volume does not confine the dis- 
cussion of the subject to Arkansas alone, but treats it also as a general 
proposition, thereby adding greatly to the usefulness of the report. 
The general synopsis of the volume, given above, defines its scope. 
The marbles and other limestones of Arkansas are very properly dis- 
cussed more in detail than any others, but a general description of 
these materials in other parts of the United States, as well as in the 
more important foreign localities, is also given. ‘The author has not 
only given his own experience and investigations in the subject in 
Arkansas and other regions, but has collected in a systematic inanner 
a large amount of useful information published elsewhere. He dis- 
cusses also very fully the geology and chemistry of marble and lime- 
stones in general, as well as their various uses for ornamental and 
structural purposes, for making cement, burnt lime, etc. The discus- 
sion of the best methods of working and utilizing marbles and lime- 
stones, together with the plates illustrating these processes, will be of 
much use to the people of Arkansas, as well as elsewhere, in devel- 
oping industries of this kind. ‘The volume is really to be considered 
a text-book on marbles and other limestones, and not a report on the 
occurrence of these materials in Arkansas alone, though the treatment 
of the subject as related to that state is of course given prominence. 
One of the most remarkable points brought out in the volume is 
the immense amount of marble contained in the state. In a belt of 
country lying north of the Boston Mountains and extending from near 
the Black River on the east to beyond Eureka Springs on the west, a dis- 
tance of more than 125 miles, the marble is continuous, and the length 
of its winding outcrops as mapped is z,812 miles. The combined area 
of the six maps necessary to represent this marble region is 4,450 square 
miles. This area extends east and west along the north slope of the 
Boston Mountains, on both sides of the White River and its tributaries, 
which run southeasterly in a general direction parallel with the moun- 
tains. ‘The rocks are approximately horizontal, or dip gently to the 
south, and the marbles, which occur in both Silurian and Lower Car- 
boniferous horizons, are exposed where they have been cut through by 
the creeks and rivers. The marbles vary greatly in quality and color, 
but many of them have been proved by practical tests made under the 
direction of the Geological Survey, to be of great strength and excel- 
lent quality. In color they vary from white to gray, pink, red, brown, 
and black, the gray, pink, red, and brown colors being the most com- 


REVIEWS. 341 


mon. In texture they vary from close grained, compact and granular to 
coarsely crystalline. 

In spite of the large quantity and good quality of much of this 
marble, very little of it has been utilized and practically none of it 
has been shipped for outside consumption. The country is only very 
sparsely settled, and this fact doubtless accounts for the limited local 
use of the marble; while the lack of shipments to outside localities is 
explained by the want of transportation facilities, the ignorance of the 
existence of this marble among those who use such materials, and by 
the fact that many people have obtained a bad impression of the stone 
in general on account of a certain very poor grade of Arkansas marble 
used in building at Eureka Springs. ‘The whole marble region is des- 
titute of railroads, except at Batesville on the eastern end, and Eureka 
Springs on the western end, so that the use of a poor grade of this 
marble at a much visited locality like the latter place, was an unfortun- 
ate occurrence. ‘The present volume will, therefore, do much good 
in removing these several difficulties. It will show some of the bene- 
fits to be derived by those who will introduce railroads into this coun- 
try, which, indeed, is full of other resources besides its marble; it will 
bring the marble to the attention of builders and architects and all 
others interested in ornamental and structural materials; and it will 
also tend to overcome the bad impression given by the use of an 
inferior marble at Eureka Springs. Even without further railway facil- 
ities, the marble, as shown by Mr. Hopkins, could be cheaply shipped 
by water on the White River. 

The chapter on ‘Carboniferous Limestones South of the Boston 
Mountains,” is by Mr. J. H. Means, and is a careful discussion of the 
subject involved. 

In’ conclusion, it may be said that the volume, besides containing 
a full discussion of the subject of marbles and other limestones, also 
gives much information on the geology of North Arkansas, and repre- 
sents a large amount of careful geological work. ‘The report is of 
much scientific and economic value, and reflects great credit on both 
Mr. Hopkins, through whose labors the great amount of work repre- 
sented in the volume and the accompanying maps has been accom- 
plished, and on the State Geologist, Dr. Branner, by whose liberal and 
broad minded policy, as well as by whose kindly interest in all inves- 
tigations carried on under his supervision, such work is possible. 

IR. Bi. Id; IPEINROS, JR, 


ACKNOWLEDGMENTS. 


The following papers have been donated to the library of the Geological Depart- 
ment of the University of Chicago, mainly by their authors: 


CALIFORNIA STATE MINING BUREAU. 
—Eleventh report of the State Mineralogist for the two years ending Sept. 15, 
1892. 612 pp. with plates and maps. 


CHAMBERLIN, T. C. 
—Annual report of the Wis. Geol. Survey, 1878, 52 pp., 1879, 72 pp. 


DAWSON, SIR J. WILLIAM. 

—On new Trees and other Fossils from the Devonian. 7 pp., 1 pl.—Quart. 
Jour. Geol. Soc., Aug., 1871. 

—Note ona Specimen of Diploxylon pom the Coal-formation of Nova Scotia. 
7 pp., ll.—lIbid., Nov., 1877. 

—Mobuis on Eozoon Canadense. 7 pp., Ill.—Am. Jour. Sci., March, 1879. 

—Comparative View of the successive Paleozoic Floras of Canada. 2 pp.— 
Proc A. A. A. S:, Aug., 1882. 

—On the results of recent Explorations of Erect Trees containing Animal 
Remains in the Coal-formations of Nova Scotia. 39 pp. 9 pl.—Phil. Trans. Royal 
Soc., pp. 621-659, 1882. Part II. 

—On the Cretaceous and Tertiary Floras of British Columbia and the North- 
West Territory. 20 pp., 8 pl.—Trans. Roy. Soc., Canada, 1883, pp. 15-34. 

—On some Relations of Geological Work in Canada and the Old World. 5 pp. 
—Trans. Roy. Soc., Canada, 1884. 

—The Geological History of the North Atlantic. 50 pp.—B.A.A.S., Sept. 
1886. 

—On the Fossil Plants of the Laramie Formation of Canada. 14 pp., 2 pl.— 
Trans. Roy. Soc., Canada, 1886. 

—On Rhizocarps in the Palzeozoic Period. 8 pp. 

—On Sporocarps Discovered by Prof. E. Orton in the Erian Shale of Columbus, 
Ohio. 4 pp.—Canadian Record of Science. 

—On the Superficial Geology of British Columbia. 34 pp., I map.—Quart. 
Jour. Geol. Soc., 1878. By George M. Dawson. 

—Presidential Address: Some Points in which American Geological Science is 
indebted to Canada. 8 pp.—tTrans. Roy. Soc., Can., 1886. 

—Note on Fossil Woods and other Plant Remains, from the Cretaceous and 
Laramie Formations of the Western Territories of Canada. 7 pp.—Ibid 1887. 

—On the Eozoic and Paleozoic Rocks of the Atlantic Coast of Canada, in Com- 
parison with those of Western Seno and of the Interior of America. 21 pp.— 
Quart. Jour. Geol. Soc., 1888. 

—Specimens of Eozoén Canadense and their Geological and other Relations. 
106 pp., I pl.—Peter Redpath Museum, 1888. 

—On Nematophyton and Allied Forms from the Devonian of Gaspé, by D. P. 
Penhallow, with Introductory notes by Sir William Dawson. 21 pp., 2 pl.—Trans. 
Roy. Soc., ‘Canada, 1888. 

—New ‘Species of Fossil Sponges from the Siluro-Cambrian at Little Metis, on 
the Lower St. Lawrence. 25 pp.—lIbid, 1889. 

—QOn New Plants from the Erian aml Carboniferous, and on the Characters and 
Affinities of Paleeozoic Gymnosperms. 28 pp., Ill.—Peter Redpath Museum, 1890. 

—On the Pleistocene Flora of Canada.—Bull. Geol. Soc, Am.—Vol. I., pp. 311- 
334. (1890). 

3H 


ACKNOWLEDGMENTS. 343 


—Note on a Fossil Fish and Marine Worm. 4 pp.—Canadian Record of 
Science, Vol. IV., April, 1890. 

—Note on a Shark and Ray obtained at Little Metis, on the Lower St. Law- 
rence. 7 pp., 1 pl.—Ibid, April, 1891. 

—New Species of Cretaceous Plants from Vancouver Island. 20 pp., 10 pl.— 
Trans. Roy. Soc., Canada, 1893. 

Notes on Useful and Ornamental Stones of Ancient Egypt. 18 pp.—Victoria 
Institute. 

—On Fossil Plants from the Similkameen Valley and other places in the 
Southern Interior of British Columbia. 17 pp., Ill.—Trans. Roy. Soc., Canada, 
1890. 

“On the Mode of Occurrence of Remains of Land Animals in Erect Trees at 
the South Joggins, Nova Scotia. 2 pp.—lbid, 1891. 

—Parka Decipiens. Notes on Specimens from the Collections of James Reid, 
Esq., of Allan House, Blairgowrie, Scotland. 14 pp., I pl.—Ibid, 1891. 

— The Correlation of Early Cretaceous Floras in Canada and the United States, 
and on some new plants of this period.—Ibid, 1892. 

The Canadian Ice Age, being notes on the Pleistocene Geology of Canada, 
with especial reference to the Life of the Period and its Climatal Conditions. 301 
pp., Ill.—Peter Redpath Museum. 

—New Species of Cretaceous Plants from Vancouver Island. 20 pp., 10 pl.— 
Trans. Roy. Soc., Canada, 1893. 

—Canadian and Scottish Geology. I1 pp. 

—On Rhizocarps in the Erian (Devonian) Period in America. 16 pp., I pl.— 
Bull. Chicago Acad. Sci. 

—Some Recent Discussions in Geology. 16 pp.— Bull. Geol. Soc. Am. Vol 5, 
pp. 101-116, 1894. 


DuMBLE, E. T. ‘ 

—A Preliminary report on the Vertebrate Paleontology of the Llano Estacado, 
by E. D. Cope. 87 pp., 23 pl.—Fourth annual report of the Geol. Survey of 
Texas, 1892. 

__A Contribution to the Invertebrate Paleontology of the Texas Cretaceous, by 
F, W. Cragin. 206 pp., 13 pl.—lbid. 

—Report on the Rocks of Trans-Pecos Texas, by A. Osann. 16 pp.—Trans- 
Pecos, Texas, by W. H. Streeruwitz, 34 pp., 1 pl.—Ibid. 

—Notes on the Geology of Northwest Texas, by W. F. Cummins. 50 pp., ll. 
— Ibid. 

—Report on the Colorado Coal Field of Texas, by N. F. Drake and R. A. 
Thompson. 125 pp. with plates and maps.—Ibid 

—Report on the Cretaceous Area north of the Colorado river, by J. A. Taff. 
pp. 241-354, with maps.—Ibid. 


GRESLEY, W.S., F. G. S. ; 
—Notes on “Cone-in-Cone” Structure. 6 pp., Ill—Geol. Mag. Jan. 1887. 


GRIESBACH, C. L., F. G. S. 

—Memoirs of the Geological Survey of India, Vol. XV., pt. 2, Vol. XVIII, pt. 
1, Vol. 23. 

—Report on the Geology of the Takht-I-Suleman. WO [Ode A jl, % waeyos— 
Records, Geol. Surv. India Vol. 17, pt. 4, 1884. 

—Afghan Field Notes. 8 pp.—lIbid, 1885. 

—Field Notes from Afghanistan: (No.3), Turkistan. 33 pp.—lbid, 1886. 

—Afghan and Persian Field Notes. 19 pp.—Ibid, 1886. 

—Field Notes: (No. 5), To accompany a Geological Sketch Map of Afghani- 
stan and North-eastern Khorassan. 10 pp., 1 map.—Ibid, 1887. 

—Notice of J. B. Mushketoff’s Geology of Russian Turkistan.—Ibid, pp. 
125-128. 

—Field Notes from Afghanistan: (No. 4), from Turkistan to India. 10 pp.— 
Ibid, 1887, pp. 17-26. 


( 


344 THE JOURNAL OF GEOLOGY. 


—Geological Notes. 10 pp.—Ibid, 1889, pp. 158-167. 

—The Geology of the Saféd Koh. 51 pp., 2 pl.—lIbid, 1892, pp. 59-109. 

—Geological Sketch of the Country North of Bhamo.—lIbid, 1893, pp. 127-130 

—Notes on the Earthquake in Baluchistan on the 20th of December, 1892.— 
Ibid, 1893, pp: 57-61, 3 pl. 

—Notes on the Central Himalayas.—Ibid, 1893, pp. 19-25, 2 pl. 

IppDINGS, J. P. 

—Microscopical Physiography of the Rock-making minerals. 367 pp., 26 pl.— 
Third Edition. 

KINAHAN, G. HENRY, M.R.I.A., F.R.G.S.1. 

—On the Formation of the ‘Rock Basin” of Loughs Corrib, County Galway. 
7 p., 2 pl—Geol. Mag., Vol. III., No, 19, 1876. : 

—Cyclopean Churches of Loughs Corrib, Mask, and Carra. 15 pp.—Univ. 
Press, Dublin, 1879. 

—Notes of Ancient Church and Toberkeelagh of Lough Mask (by Joseph 
Nolan). With notes on Ancient settlements in Galway (by G. H. Kinahan).— 
Jour. His. & Arch. Assoc. of Ireland, 4 pp., 1871, 

—Antiquities in Yar Connaught.—Roy. His. & Arch. Assoc. of Ireland. 4 pp., 
1871. 

—Type of Clochaun and a remarkable cross southward of Louisburg. 2 p., I 
pl., 1871. 

—/folian drift or blowing sand. 4 pp.—Geol. Mag., 1871. 

—Notes on some Megalithic structures. 4 pp.—Jour. Roy. Hist. & Arch. Assoc. 
of Ireland, 1872. 

—General Glaciation of Yar Connaught (assisted by M. H. Close, Dublin). 20 
pp., Map., 1872. 

—The Valley of Loch Lomond. 7 pp.—Trans. Geol. Soc. of Glasgow, Vol. 
Wr, 1PEnAE 2, 

—TInscribed stones, County Mayo. 21 pp.—lIll.—Proc. Roy. Irish Soc., Vol. 
Weg 4897/3 

—Water Basin of Lough Derg, Ireland. 8 pp.—Geol. Mag. Vol. XI., 1873. 

—Microscopical structure of Rocks. 72 pp., 5 pl.—Proc. Roy. Irish Acad., 2d 
Slo, Woll, WW, 137/50 

—Geology of West Galway and S. W. Mayo, Ireland. 10 pp.—Geol Mag., 
Oct., 1874. 

—Re-arranged Glacial Drift. 13 pp.—lIbid, April, 1874. 

—On antiquities in the neighborhood of Drumdarragh, County Antrim. 7 pp.— 
Jour. Roy. Hist. & Arch. Assoc. of Ireland, April, 1875. 

—The estuary of the River Slaney, County Wexford. 10 pp. 

—The drifting power of tidal currents, versus that of wind waves. 15 pp. 

—The lagoons on the southeast coast of Ireland. 13pp.,1 pl. Proc. Instit. 
Civil Engin., Vol. XLIV., Part 2, 1875-6. 

—TIrish tide heights and raised beaches. 4 pp., Geol. Mag., Feb., 1876. 

—lrish drifts. 15 pp. 

—The rocks of the Ballymoney Series, County Wexford. 7 pp. 

—Quartzite (quartz-schist), quartz-rock (greissen). 11 pp.,1 pl. 

—On the Chesil Beach, Dorsetshire, and Cahore Shingle Beach, County Wex- 
HOG; 1B jojo, i jl. 

—Cambro-Silurian and Silurian rocks of the southern and the western parts of 
Ireland. 4 pp., 1 pl.—Scientific Proc. Roy. Dublin Soc. 

—The old red sandstone (so-called) of Ireland in its relations to the underlying 
and overlying strata. 8 pp., 2 pl. Scientific Proc. Roy. Dublin Soc. 

—QOn a submarine crannog (discovered by R. J. Ussher), at Ardmore, County 
Waterford. 5 pp., I pl.—Proc. Roy. Irish Acad., 2d Ser., Vol. II., Dec., 1880. 

—Diagram of the Irish Paleozoic rocks, showing a nearly continuous sequence 
from the coal measures to the Cambrian. 4 pp., t diagram. 

—Dingle and Glengariff grits. 5 pp., 1 pl—Proc. Roy. Dublin Soc. 

—On the Arklow Beach and Rivers. 5 pp., 3 pl.—Proc. Royal Dublin Soc. 


ACKNOWLEDGMENTS. 345 


—Supposed Upper Cambrian rocks in the Counties of Tyrone and Mayo. 4 
pp.—Proc. Roy. Irish Acad., 2d Ser., Vol. I. (Science), No. 5, Dec., 1880. 

—Report on the rocks of the Fintona and Curlew Mountain districts. (With 
Paleontological remarks by W. H. Baily). 25 pp., 2 pl.—Proc. Roy. Irish Acad., 
2d Ser., Vol. III. (Science), No. 7, Dec., 1881. 

—Anniversary address to the Royal Geological Society of Ireland. 10 pp.— 
Proc. Royal Dublin Soc. 

— Possible Laurentian Rocks in Ireland. 3 pp.—Geol. Mag., Vol. VIII., 
Sept., 1881. 

—Anniversary address to the Royal Geological Society of Ireland. i) jO}O— 
Proc. Roy. Dublin Soc., Vol. III. 

—Sepulchral and other pre-historic relics, Counties Wexford and Wicklow. 8 
pp., 2 pl. 

—Megalithic structures, Counties Wicklow and Carlow. 3 pp., 4 pl. 

—Notes on Fault-rock. 4 pp. 

—Palzeozoic rocks of Galway and elsewhere in Ireland, said to be Laurentian. 
10 pp., 3 pl.—Proc. Roy. Dublin Soc., Vol. III. 

—On acircular structure at Cumber, County Wexford. 4 pp., I pl. 

—Glacial moraines on Mount Leinster, Counties Wexford and Carlow. 2 pp., 
3 pl.—Proc. Roy. Dublin Soc., Vol. III. 

—Inscribed stones, County Donegal. 2 pp., I pl.—Proc. Roy. Irish Acad., 2d 
Ser., Vol. II., No. 5, Feb., 1883. 

—Crude suggestions on the nomenclature of rocks. 5 pp-—Trans. Edin. Geol. 

Soc.--Notes on the Cervus Megaceros (Megaceros Hibernicus). 3 pp.—Ibid. 

—On the Killary Bay and Slieve Partry Silurian Basin, also notes on the meta- 
morphic or Northwest Galway (Yar-Connaught). 21 pp. 

—The Laurentian rocks and metamorphism. 4 pp. 

—Notes on the apatite of Buckingham, Ottawa County. 2 pp.—Proc. Roy. 
Dublin Soc. 

—Notes on the classification of the bowlder clays and their associated gravels. 
4 pp.—Ibid. 

—Metamorphic action. 5 pp.—Proc. Roy. Trish Acad., 2d Ser., Vol. IV., No. 4 
(Science), Feb., 1885. 

—Notes on some of the Irish crystalline iron ores. 19 pp.—Proc. Roy. Dublin 
Soc. 

—Canadian Archzean, or Pre-Cambrian: rocks; with a comparison with some 
of the Irish metamorphic rocks. 14 pp.—lbid. 

—On a possible Genesis of the Canadian apatite. 10 pp. 

—Trish and Canadian rocks, compared. 10 pp.—Geol. Mag., April, 1885. 

— Table of the Irish Lower Palaeozoic rocks, with their probable English 
equivalents. 6 pp.—Proc. Roy. Dublin Soc. 

—The terraces of the Great American Lakes and the Roads of Glenroy. 3 pp. 

—Notes on the coal seams of the Leinster and Tipperary coal-fields. 8 pp., I 
pl.—Proc. Roy. Dublin Soc. 

—On Loch Betha, County Donegal. 4 pp.—Proc. Roy. Irish Acad., 2d Ser., 
Vol. IL., No. 8, Jan., 1886. 

—Oldhamia. 5 pp.—Proc. Roy. Dublin Soc. 

—Marsh (Natural) Gas. 10 pp. 

—Deal Timber in the lake basins and peat bogs of Northeast Donegal. 9 
pp.—Proc. Roy. Dublin Soc. 

—On geological unconformabilities. 6 pp.—Ibid. 

—On an inscribed rock surface at Mevagh, Rosguile, County Donegal, Ire- 
land. 2 pp., 1 pl. 

—Barnes’ inscribed Dallaus, County Donegal. 1 p. 

—The Mevagh inscribed stones and other antiquities. II pp. 4 pl.—Jour. Roy. 
Hist. & Arch. Assoc. of Ireland, No. 76, Oct., 1888. 

—A new reading of the Donegal rocks. 20 pp., 6 pl.—Proc. Roy. Dublin Soc. 

—Quartzite and Quartz-rocks. 5 pp.—lzish Naturalist, Vol.1., No. 8, Nov. 1892. 


346 THE JOURNAL OF GEOLOGY. 


—Quartzite and Quartz-rock. 5 pp.—Ibid, Vol. I., No. 9, Dec. 1892. 

—On a pre-historic road, Duncan’s Flow, Ballyalbanagh, County Antrim. 5 pp. 

—Laccolites. 2 pp.—Geol. Mag., Dec. 2, Vol. VIII., No. 3, March, 1881. 

—Report on the microscopical structure of rocks; (No. 4). Igneous rocks. 
3 pp.—Proc. Roy. Irish Acad., 2d Ser., Vol. I1., July, 1875. 
By KINAHAN, GERARD H. 

—Eurites or Basic Felstones of Silurian Age. 5 pp.—Proc. Roy. Irish. Acad., 
Dec. 1880. 

—“Black Sand” in the Drift north of Greystones, Co. Wicklow. 4 pp.—Proc. 
Roy. Dublin Soc. 

—Report on the Clearing of Peaty Waters. 9 pp.—Roy. Irish Acad., Dec. 1882. 

—On the Mode of Occurrence and Winning of Gold in Ireland. 23 pp., 2 pl. 
Proc. Roy. Dublin Soc., Vol. 3, part 4. 

—Some Notes on the Geology of Bray Head, with a Geological Map and Sec- 
tions. 5 pp., 3 pl.—Ibid, Vol. 3, part 6. 

—Note on the Coal Deposits of the Northwest Territories of Canada. 4 pp.— 
Ibid, 1884. 

—Lisbellow Conglomerate, County Fermanagh, and Chesil Bank, Dorsetshire. 
3pp-, 1 pl. 

—Journal of the Royal Geological Society of Ireland, Vol. 8, parts 1, 2 and 
3, (1886 to 1889). 

—A Handy Book on the Reclamation of Waste Lands, Ireland. 141 pp., I pl. 
1882. 

—Manual of the Geology of Irelnad. 444 pp., I map. 

—Valleys and their relation to Fissures, Fractures and Faults. 240 pp., 1 pl.— 
1875. 


THE 


OW RENE we Or GhOLOGY 


MAY-JUNE, 1894. 


THE NORWEGIAN COAST PLAIN. 
A NEW FEATURE OF THE GEOGRAPHY OF NORWAY. 


THE western part of the Scandinavian peninsula is generally 
spoken of in geographical descriptions as simply sloping down to 
the sea. This is not exactly true, for there are, along the coast 
low, almost level tracts which I propose to unite under the term, 
The Norwegian Coast Plain. This plain begins on the seaward 


Fic. 1. Mount Siggen rising above coast plain. 


side with small, naked islands surrounded by shallow water ; far- 
ther towards the land, it forms a low rim around the higher 
islands, or constitutes, of itself, rather considerable islands; still 
farther on, in the outer parts of the fjords, it may be observed 
along their sides. This coast plain generally rises towards the 
land. The height is varying; probably one hundred meters may 
be the uppermost limit. This feature in the geography of our 
country has previously been noted by the author, and by other 
347 


348 THE JOURNAL OF GEOLOGY. 


observers, so far as regards portions of the coast, but the obser- 
vations have not before been brought together as a unit, and 
viewed as a general feature. The annexed little map (1:400,000) 
shows one of the coast islands to the south of Bryan, encircled 
by many other smaller islands and skerries (Fig 2). The coast 
plain is made black, and the parts rising above it are marked 
with hachures. In the middle of the large island, one will 
remark a small white cross. If a person were to stand there 
and look towards the south- 
east, he ‘would see the land- 
scape represented in the ac- 
companying sketch (Fig 1), 
in which the mountain Siggen, 
and some smaller mountains 
(GO) tlaxS SoOwiclnvesic Oe ie ace 
seen rising above the coast 
plain. The next picture (Fig 
3) is probably still more char- 
acteristic. It gives a view of 
some islands at a little dis- 
tance north of the town, 
Bergen. The island, which 
looks “like a hat, is Alden, 
1,500 feet high. The name 
of the island group with the 
three small knolls is Varoc. 
The low tracts, here repre- 
sented, are not built of loose 


anti iit. 


il 


= 


materials as one might sup- 
Fic. 2. Region of Bommeloe. PS from the SN PIOSEU ENS but 
are almost all carved from 
solid rock, and hard rock too, viz., crystalline schists of different 
kinds, dioritic rocks and conglomerates. The region of Bommeloe, 
illustrated above, also has a very complex geological structure. 

These are some instances of the mode of occurrence of the 
remnants of the coast plain. The plain may be traced along our 


whole western coast from 50° north latitude to the extremest 


THE NORWEGIAN COAST PLAIN. 349 


frontier towards Russia. A map of it will be communicated to 
the ‘Year-book of the Geological Survey of Norway for the 
years 1892-3. Kristiania, 1894.” 

The coast plain is rather rough and uneven, with small val- 
leys, and often with innumerable small crags. This roughness 
of the coast plain, which is partly covered by the sea, has pro- 
duced the myriads of islands, large and small, and the skerries, or 


Fic. 3. Mount Alden and the Varoc Islands. 


insulated rocks, which are scattered along the greater part of the 
Norwegian coast. On this coast plain lie the towns of Havanger, 
Bergen, Tromsoe, and others. Here live hundreds of thousands 
of people out of our two millions. It is thus seen to be of great 
importance to our nation. Without it, the whole western coast 
would be like the bare region east of North Cape, where the 
coast plain is generally wanting. 

_ The coast plain is a plain of denudation, or a base-level. 
“Tt marks a sea-level, to which the land has been reduced by 
sub-zrial forces.” It is glaciated and, in the author’s opinion, it 
has been worked out in periods previous to the glacial period, 
and in the intervals of that time, when the land was free from 
ice. The time that has elapsed since the ice-age is too short to 
be of any importance for the great work performed. 

In comparison with the great geographical phenomena here 
treated, the present strand-lines are small things, though they 
give evidence that the forces, which made the coast plain, are 
still working. It has occurred here, as so often elsewhere, that | 
one remarks the small things before the great ones. 

Hans REUvSCH. 


GLACIAL CANONS. 


Historical Note-—This paper was presented before the Ameri- 
can Association for the Advancement of Science at the Minne- 
apolis meeting, where it was kindly read by Mr. Warren Upham 
in the absence of the author. A brief abstract was printed in 
the proceedings of that body for 1883, page 238. Subse- 
quently, Dr. J. E. Hendricks, long editor of Zhe Analyst, did the 
favor of reviewing the mathematical portions, and his sugges- 
tions are embodied in a note. 

The paper is the fruit of field studies in the Sierra Nevada, 
mainly in the region about Lake Mono, and of subsequent office 
work in Salt Lake City, under the direction of I. C. Russell, then 
of the United States Geological Survey, in 1882 and 1883. The 
paper was not published because it was recognized that one of 
the most important phases of ice work (7. é., the work at the bot- 
tom of the Bergschrund involved in the formation of cirques 
and rock basins) was not adequately treated. It was then, as 
it is now, the opinion of the author that ice work is concentrated 
and culminates in effectiveness in cirques, whether at the heads 
of water-carved tributaries (cyms or coombes) or in amphitheatres 
below ice-falls due to varigradational irregularities in the ante- 
cedent water-cut profiles, and that this concentration is proved 
and the correct analyses of the process suggested by the Bergs- 
schrund in the one case and by seracs in the other; but the 
analysis is difficult, and neither then nor later have opportunities 
occurred for working it out. Recently this phase of ice work 
has been taken up by Mr. Willard D. Johnson, who brings to the 
work a rich fund of observation and an acute and vigorous mind, 
while at the same time the author finds the promise for the desired 
opportunity for further study fading away; so it is deemed 
best to publish in the present form, leaving extension and appli- 
cation to others. It may be observed that, while the treatment 
350 


GLACIAL CANONS. 351 


of the subject in this paper is analytic, the work was primarily 
synthetic and based directly on field observations and inferences 
in the magnificent field of the southern Sierra. 


lle 


Glacial cafions are characterized by several peculiar features : 
1. They are U shaped rather than V shaped in cross-profile ; 
2. Small tributary gorges usually enter at levels considerably 
above the cafion-bottoms; 3. In longitudinal profile the cafion- 
bottoms are irregularly terraced—z. ¢., made up of a series of 
rude steps of variable form and dimensions,—and some of the 
terraces are so deeply excavated as to form rock-basins occupied 
by lakelets; 4. The cafions are sometimes locally expanded into 
amphitheatres; 5. The cafion-bottom is not always obdurate rock, 
but may consist of coarse fragmental debris in which individual 
blocks are as deeply striated and as smoothly polished as are 
the most solid ledges, though they may rest so insecurely in their 
positions that a hand can overthrow them; and 6. The volume 
of glacial debris in moraine and valley deposits is but a small 
fraction of the cubic content of the cafion from which it was 
derived. 

Of these features the first four suggest that glaciers are most 
effective engines of erosion, while the last two indicate that 
glacial erosion is inconsiderable. The source of the apparent 
discrepance may be sought through analysis of the agencies 
involved in the development of the four features first enumer- 
ated. 


Me 


Whatever be the physical cause of ice-flow, the motion of a 
glacier is unquestionably determined by (1) the weight of the 
ice, (2) the declivity of the channel, (3) the share of potential 
energy not expended in overcoming internal cohesion, and hence 
available in producing mass motion, and (4) the friction against 
bottom and sides of the channel; of which factors the last two 
(one of which is positive and the other negative) are indeter- 
minate. The united effect of all—z. ¢., the total sum of potential 


352 THE JOURNAL OF GEOLOGY. 


energy available in generating movement—may be denominated 
the down-stream impulse of the glacier. Such impulse, in com- 
bination with the simple wezght of ice at any point, constitutes 
the zntensity of glacial action at that point. 

But, ceteris paribus, the measure of rock-grinding is the friction 
between the glacier and its bed. Now such friction is a complex 
function of the weight and down-stream impulse, and varies with, 
but probably less rapidly than, their product. The general law of 
friction, applicable under wide ranges of pressure and velocity, 
has never, indeed, been clearly formulated; and where the con- 
tiguous surfaces are so unlike as rock and ice the friction is 
scarcely known even in the simplest case." In case of such 
substances, too, if detached rock-fragments intervene, they will 
-project into the more yielding material and thereby increase 
the frictional surface; when the slip may either (1) occur in 
part on each side of the fragments (2. ¢., the ice may flow over 
the fragments, while they themselves move at a slower rate 
‘over the valley-bottom, as has, indeed, been observed by 
Niles), or (2) may be confined to the inosculating rock-surfaces. 
Also, if a continuous sheet ot comminuted debris intervene, 
the movement may be divided between its upper and lower sur- 
faces ; and if the intercalated sheet be thick, several planes of slip 
may exist within it and its own motion become differential. 
Again, if fragments of large angles and not greatly different diam- 
eters project into the ice or lie within a differentially-moving 
ground moraine, the unequal flow will most rapidly carry for- 
ward their summits, initiate rolling, and thus diminish friction 
(and at the same time, perhaps, produce ‘“ fluxion-structure’’). 
It follows that the friction in any given case cannot be even 
approximately evaluated; and its expression must, therefore, 
include an indeterminate factor of considerable moment. 

But, again, the disposition to attack the glacier-bed is 


* Tylor found that with a pressure of two pounds to the square inch the co-efficient 
of friction of ice upon ice was between 0.1 and 0.2, and concluded that glacier motion 
would be impossible without water to lubricate the bottom. Geol. Mag., Dec. IL, 
Vol., II., 1875, p. 280. 


GLACIAL CANONS. 3513 


(ceteris paribus) measured by the ratio between weight and down- 
stream impulse; for manifestly, if the weight be in excess, the 
predominant tendency must ever be to fix and retain in their 
places all bowlders, pebbles, sandgrains, and smaller particles ; 
when the weight and impulse are as w and vin the diagram 
(fig. 1) their resultant will tend to retain rather than remove 


Fic 1. 


such fragments, and transportation will be limited to that due 
to friction and sub-glacial water; when the factors are equal, as 
are w’ and v’, their resultant will tend equally to retain and to 
remove particles, and the effects of friction and flowing water 
will be counteracted by the greater specific gravity of rock than 
ice; and when the ratio is as w" to v", the disposition will be 
to overturn and sweep forward all fragments. Also, the weight 
of ice tends to produce crushing of the rock in a degree probably 
increasing increasingly with its value. Finally, with increased 
weight will go increased pressure-liquefaction of the ice, and 
from this will result the antagonistic effects of reduced fric- 
tion and augmented transportation. The last two agencies are 
variable, only very roughly determinate in the ordinary case, and 
generally of inconsiderable value. They may be thrown together 
as an unknown factor which, in conjunction with the predominant 
first agency, constitutes the effectiveness of glacial erosion at any 
point. 

The three elements of znéensity, friction, and effectiveness, there- 
fore, determine the rate of glacial erosion. To more succintly 
express their relations, let-— 


w—weight of ice at any point ; 

v=down-stream impluse at any point. 

s=rock-surface in contact with any vertical prism of ice ; 
2x=unknown factor in friction term; and 

z=unknown factor in effectiveness term. 


354 | THE JOURNAL OF GEOLOGY. 


Then, denoting the three elements by their initials : 
A= SOs 
_ WUX 


I= ainda 
s 


U 


Obviously, these elements are of unlike value in different 
parts of the cross-section of a glacial valley, and the rate of 
erosion is hence differential ; but since important unknown factors 
are involved, no reliable expression either for the absolute rate 
of erosion at any point, or for the ultimate form of the glacial 
bed, can be directly deduced. The general tendency of glacial 
action may, however, be learned from separate consideration of 
the individual tendencies of the several agencies comprehended. 


*In the above statement, it has been the purpose to eliminate what is thought to 
be an element of uncertainty in the extension of the customary formula for friction to 
quantities so great and so peculiarly conditioned as those involved in the move- 
ments of great glaciers. It might be simpler also, as Dr. Hendricks points out, 
to reduce the determinants of glacier motion to those of positive action—viz., 
(1), the weight of the ice, (2), the declivity of the channel, and (3), the potential 
energy available in producing mass motion—by excluding the negative determinant, 
friction. The down-stream impulse might also be represented by zw sinO, x being 
an unknown factor depending on molecular force, and hence involving temperature, 
etc. Then, making «x the co-efficent of friction, the equations would become: 


J=w X nw sin; 


F=w x cosO,; and 


Paid se. 
w x cosO 
Or, introducing the factor f (v) to represent the influence of velocity of flow in 
determining the friction; the last two equations would become : 
F=w x cosO X f (v);-and 
vy + F 
i= (2) oun ee 
wx cos? X f (v) 
It will be observed that this modification of the equations for zzéensity, friction, and 
efficiency do not materially affect the discussion, and do not in any way detract from 
the conclusions reached. ‘The original equations are retained, however, in the opinion 
that they suggest, if they do not actually present, the more direct and serviceable mode 
of analysis. 
It is a pleasure to acknowledge obligation to Dr. J. E. Hendricks, of Des Moines 
for working out the expressions in this note (January 25, 1885). 


CLAGIATERGAINONS: 355 


In such consideration let the ice be assumed to occupy a 
previously-formed gorge of the typical V form of water-cut 
canons. 


The weight of the ice varies directly with its thickness, and 
accordingly increases progressively from sides to center of the 
gorge. The tendency of this factor is hence to continually 
deepen the cafion and to perpetuate the V form. 

Three of the four factors into which down-stream impulse 
may be resolved are of unequal value in different portions of the 
width of the glacier, and from such inequality the differential 
flow of ice-streams results; for from sides to center the weight 
increases uniformly, the available energy increases increasingly, 
and the friction probably increases less rapidly than the thickness ; 
whence the impulse at the center must ever remain predominant. 
But if the ice-stream be conceived to consist of a parallel series 
of longitudinal vertical laminze (for in the present discussion the 
vertical variation of flow is immaterial), it is evident that those 
at the edges will be retarded by the valley-sides, that the medio- 
lateral laminze will be equally retarded and accelerated by their 
unequally flowing neighbors, and that the central lamina will be 
retarded by the more slowly moving ice on either side; and if 
the mutual interaction of the various laminz be considered, that 
the platted ordinates of flow will form a curved figure, and 
not a triangle homologous with the cross-section of the gorge 
(fig. 2). Such indeed is the case of differential ice-flow, as 
empirically established by Forbes, Agassiz, Tyndall, and other 
observers; though inthe V gorge the curve would unquestionably 
be less flattened than in the U gorges within which the measured 
glaciers lie. On the whole, the disposition of the second factor 
must be to most energetically attack the valley-bottom, but at the 
same time to develop concavity of the valley-sides. 

Summarizing, it appears that the general tendency of the inten- 
sity element is preéminently to deepen the canon and slightly 
to transform the V to a U profile. 


350 Wel JKONGHRINAUL (OF (CSR OVL OG IE 


Of the factors peculiar to friction, that of indeterminate value 
doubtless suffers increasing relative diminution as the depth of 
ice increases, and its platted ordinates (expressed in terms of the 
valley-profile) will hence form a curve of materially less depth 
than the triangle formed by the tangents to its extremities (fig. 
2). The disposition of the factor is accordingly to widen the 
gorge and develop the U profile. 


Fig 2. 


With the less lateral velocity common to ice-streams will go 
reduced lateral friction, and hence erosion, in a ratio correspond- 
ing to the velocity curve; and for a second reason, there- 
fore, will concavity of the valley-sides be engendered and 
developed; though the concurrent disposition will be to deepen 
the gorge. 

Whenever concavity of the valley-sides obtains, the contact 
surface of the vertical prism will become variable. If, now, fric- 
tion vary approximately with the pressure of the incumbent ice, 
the consequent erosion will diminish with the increasing slope 
toward the edges of the glacier; when the disposition will be to 
deepen the gorge and restore the V form; but if the friction vary 
more nearly with the contact-area, it will increase with the slope, 
and the resulting erosion will tend to widen the gorge and, in 
another manner, to restore the V profile. Whichever tendency 
obtains will, however, be secondary and ever subordinate to that 
of the principal factors of friction. (Subglacial water will at 
once reduce friction and promote transportation directly and 
corrasion indirectly; also it will tend, ceterts paribus, to form a 
continuous film between ice and rock reaching upward to 0.92 
of the thickness of the glacier, or, if the glacial surface be highly 
convex, perhaps quite to its margins. On the whole, then, its 


CRAGTAIN GANOINS: 357 


influence in any direction must be slight, and its effect may be 
disregarded). 

Combining the several antagonistic factors, it appears uncer- 
tain whether the general tendency of the friction element is to 
widen or deepen the gorge, but certain that it is to develop con- 
cavity of the valley sides and the U form of canon. 


Since the third and fourth factors in down-stream impulse 
(available potential energy and friction) are indeterminate, the 
problem as to the declivity required to render such impulse equal 
to the weight at any point in a given glacier, or even as to 
whether such equality ever obtains in nature, cannot be analyt- 
ically solved; and very few observations showing the relative 
value of these components have ever been made. Niles,* how- 
ever, found that in the Great Aletsch glacier the ice usually rides 
upon projecting rugosities and seldom fills the intervening 
depressions of its bed, and that a bowlder (itself slowly moving) 
three feet high had formed an inverted trough thirty feet long 
in the base of the incumbent ice; whence the down-stream 
impulse must have exceeded ten times the weight. Bonney,’ 
also, in the Glacier des Bois and the Glacier d’ Argentiere, found 
all broad and gentle depressions in the glacier beds filled with im- 
pressed ice, the narrower depressions not quite filled, the lee of 
projecting knobs protected for a distance equal to their height, and 
bowlders lying zm setw beyond the present terminus of the ice gla- 
ciated above and below (showing that here also motion took 
place along the two planes), all of which phenomena indicate 
that, in these glaciers, the down-stream impulse is in excess of 
weight, but in a less degree than in the Great Aletsch. The 
several observations then demonstrate (1), that down-stream 
impulse may greatly exceed weight, and (2), that the relation 
is variable. All were in the upper portions of the valleys where 
the declivity is great (15° to 20° in the examples described by 
Bonney ), and where the office of the glaciers is preéminently one 

*Proc. Boston Soc. Nat. Hist., XIX., 1878, 330; Am. Jour. Sci., XVI., 1878, 366. 
? Geol. Mag., Dec. II., Vol. III., 1876, 197. 


358 THE JOURNAL OR GHOLOGY: 


of erosion. Now ordinary valleys, whether occupied by streams 
or glaciers, are of progressively diminishing declivity from source 
to terminus; ordinary glacial valleys exhibit successive zones of 
active erosion, feeble erosion, slight deposition, and abundant 
deposition in passing from their upper reaches to the broader 
valleys into which they embouch or upon the plains with which 
they merge; and in such cases the down-stream impulse must 
wane to practically nothing at the extremities of the glaciers, and 
must hence greatly fail of the weight. It follows that at some 
point (or at diverse points) in every extended glacier-course 
the components weight and impulse are equal at the centre of 
the glacier. 

Since glacier ice but slightly approaches perfect fluidity and 
the flow of the center is greatly retarded by the sides, the ratio 
of impulse to weight (and with it the effectiveness) continually 
and largely increases from center to sides: if the central effec- 
tiveness be just zero, that at the sides will nevertheless remain 
important; if it be minus centrally, it may still be considerable 
laterally ; and however great may be its value at the center, it must 
have far greater value at the sides. The disposition, then, will ever 
be to protect the bottom and equally to attack the sides of the 
valley ; and since the down-stream impulse of the several parallel 
laminz forms a curve when platted, so will the disposition also 
be to form concave valley-sides. 

Of the unknown factor in the effectiveness term, the first 
component (rock-crushing) can be but trivial in the ordinary 
case, while the second (pressure-liquefaction) exercises antagon- 
istic influences. It may, accordingly, be safely neglected. 

Collectively, the tendencies of the third element of glacial 
erosion are (a0) to effectually protect the valley-bottom through- 
out a considerable portion of the glacier course, (2) to develop 
the U form of canon, and (3) to materially increase the relative 
width of the gorge. 

The fifth feature of glacial cafions is explained by the opera- 
tion of this element, and in turn establishes the importance of 
the element. 


GLACIAL GANONS: 359 


Recapitulating, it appears that of the several elements 
involved in glacial erosion, the first tends to deepen the gorge 
and slightly to develop the U form, the second to develop the U 
form, and perhaps very slightly to deepen the gorge, while the 
third and predominant one tends strongly to widen the gorge 
and protect its bottom, and less strongly to develop the U form. 
It follows that the general tendency of glaciers must be to widen 
rather than deepen the valleys they occupy, and to transform 
V to Ucafions. Also, since the typical U gorge is just such as 
would result from temporary occupancy of a V gorge by a 
glacier, while the ordinary ratio of width to depth is less than 
would obtain were the gorge eroded by glacial action exclusively, 
it follows again that the characteristic glacial cafions must be 
only modified stream-cafions. 

This conclusion explains, and is equally and directly corrob- 
orated by, the first and sixth features of glacial cafions. It also 
fully warrants the assumption, in the following as in the forego- 
ing discussion, of originally V shaped glacier-beds. 


JUU. 


As elsewhere shown,! corrasion of a stream is a function of 
its volume, and, ceteris paribus, varies with, but less rapidly than 
that element. In a region of rapid corrasion then, the main 
stream must (unless the declivity be materially unlike) more 
rapidly corrade its channel than does its minor tributary ; and the 
tributary cafion must accordingly enter its principal over a rapid 
or at least a convex curve in longitudinal profile. 

If now the main cafion become filled with ice and be trans- 
formed from the V to the U type by its action, the distal 
extremity of the tributary will be cut off and the original stream- 
formed declivity replaced by the precipitous side-wall of the 
normal glacier valley (fig. 3); and this result will follow whether 
the tributary be filled with or free from ice, provided corrasion 


*“VThe Formation of River Terraces” (recently published in Eleventh Annual 


Report U. S. Geological Survey, 1891, pp. 259-272). 


360 TALES JO TAN ALE OLN GIAOLO GNA 


at the cafion-mouth be not relatively increased in a’considerable 
degree. ; 

It follows that the second feature of the typical glacial 
cafions may naturally result from temporary occupation of water- 
cut cafions by ice, and that it does not necessarily argue profound 
glacial erosion. 


IY 


In obedience to the law of varigradation,* all and particularly 
smaller streams tend to depart ina minor degree from uniform 
gradient, and to develop in their channels a longitudinal profile 


PIG. 3: 


of slightly variable declivity ; this law finding expression in the 
alternating pools and rapids of mountain brooks and in the 
always perceptible and often conspicuous alternations of greater 
and less declivity in the courses of water-cut cafions. 

If now an otherwise uniform V canon of irregular gradient 
become occupied by a glacier, the flow, varying as it does with 
the declivity, will become unequal and the ice will tend to accu- 
mulate on the planes of low declivity until it approaches a uni- 
form surface slope; when the weight of ice at different points in 
the medial or other longitudinal plane of the glacier will become 
variable, and will reach a maximum over the greatest depression 
(fig. 4). With such increased weight will go (a) direct increase 
of intensity with the augmentation of its principal factor, (0) 
indirect increase of intensity in virtue of the office of weight asa 
function of the down-stream impulse, and (c) direct diminution 


‘Op. cit, p. 295. 


GLACIAL CANONS. 361 


of intensity in consequence of the absolutely reduced down-stream 
impulse; also (2) material increase of friction with the augmen- 
tation of its principal factor, and (¢) less material diminution of 
friction in consequence of the reduced impulse; and finally (/), 
direct diminution of effectiveness with the absolute decrease of 
impulse, (g) indirect diminution of effectiveness in consequence 
of the relative decrease of the same factor, and (Z) direct but 
slight increase of effectiveness in virtue of the operation of the 
obscure factor of rock-crushing and pressure-liquefaction; or, 
summarily, increase in intensity, slight increase in friction, and 
decrease in effectiveness. 

Now, in view of the obscure and antagonistic though inter- 


Ie 


a 


1 
\ 


i. 
fi 
/ 
oleae Soe ee 


Fig. 4. : 

dependent relations involved, it is evident that without exhaust- 
ive quantitative investigation (impossible in the present absence 
of knowledge concerning friction between ice and other substan- 
ces) it cannot be determined in the ordinary case whether the 
disposition will be to erode the more rapidly where weight 
increases at the expense of declivity, or where the reverse occurs ; 
but it appears quite certain that where the surface declivity 
materially exceeds that at the base, and where, accordingly, the 
impulse is not reduced proportionally to the declivity of the 
channel, erosion must progressively increase with the weight. If 
so, the tendency of glaciers must be to cumulatively intensify 
the irregularities in gradient normal to water-cut cafions. 

But corrasion and transportation in any part of a glacier-bed 
are limited directly by flow of ice and indirectly by coincident 


362 THE JOURNAL OF (GEOLOGY. 


flow of subglacial water. Now, loss of effectiveness through 
absolute and relative increase of weight must eventually become 
potent in retarding direct excavation of the depression; also, 
whenever the depression becomes so considerable as to possess 
reverse slope toward its distal extremity, gravity will no longer 
enhance, but instead oppose, direct transportation of detritus; 
again, with increased depth of depression will go increased cross- 
section and concomitant and material diminution of velocity and 
eroding capacity in the ice-stream; and finally, the longitudinal 
perimeter of the depression must continually increase until the 
fricton along it approaches and ultimately equals the shearing 
strength of the ice along its chord, whence the movement of the 
basal segment.must concurrently diminish and gradually cease. 
In like manner, when the normal slope becomes reversed, gravity 
will oppose and not enhance transportation by subglacial water ; 
also, as the reverse slope increases, the flow of such water will 
become sluggish and its capacity diminished; and finally, when 
the depth of depression below its distal rim reaches 0.92 of the 
maximum depth of ice (or when 6-c equals 0.92 a-c, fig. 4), the 
subglacial water will assume static equilibrium, the incumbent ice 
will suffer flotation, and both corrasion and transportation will 
practically cease. Thus the excavation of depressions by direct 
ice-action has a definite though indeterminate limit, and can prob- 
ably never exceed a moderate fraction of the depth of the ice; 
and thus also indirect glacial erosion in depressions through the 
coéperation of subglacial water alike in corrasion and transporta- 
tion will remain effective until the depth of excavation approaches 
the thickness of the incumbent ice; whence, in the general case, 
the measure of maximum excavation of rock-basins is a large 
fraction of the depth of the glacier. 

(Evidently embouchures of valleys, zones of abrupt diminu- 
tion in declivity, points at which for any reason glaciers termi- 
nate for considerable periods, broad cross-valleys beneath 
continuous ice-sheets, and all localities where the surface slope 
of the ice materially exceeds the slope of its base, will form as 
definite loci of active excavation as do the ordinary planes of 


ECLACIML CANONS, 1% 363 


low declivity developed by varigradation; and at such localities, 
accordingly, glacial lakes, the submerged rock-basins characteris- 
tic of fjords, and other evidences of energetic ice-action remain 
after the melting of the ice.) 

It follows, then, that the third feature of glacial caMons may 
result simply from glacial occupation of water-cut cafions; and 
since in the common mountain region from which the glaciers 
have completely disappeared the irregularities of gradient pecu- 
liar to such cafions are not greatly intensified, while glaciated 
rock-basins are comparatively rare and of slight depth, it equally 
follows that the occupation was only temporary, and the sum of 
glacial erosion relatively inconsiderable. 


Vv. 


The immediate effect of the origin of a tributary cafion ina 
developing drainage-system is the exposure of a greater length 
of canon-wall to degradation; from which effect in turn results 
(under certain conditions of homogeneity of terrane and uni- 
formity of altitude in the region, and hence of repeated bifur- 
cation and wide dispersal of the branches of the nascent tributary ) 
the formation of an amphitheatre opening into the main cafion. 
Then, after the considerable development of the tributary, its 
disposition will be, as shown by Warren,” to dam the main stream 
and diminish the declivity above its confluence ; whereby lateral 
corrasion will increase at the expense of vertical corrasion there. 
Thus, by increased lateral corrasion the amphitheatre will ever 
tend to expand within certain limits immaterial in this discussion. 
Such amphitheatres, exhibiting the tortuous outlines character- 
istic of fluvial erosion, have been well illustrated by Dutton,? and 
are common features in many mountain regions. 

If now a glacier enter and fill such an amphitheatre, its rate 
of flow and similarly its rate of erosion on the given area will be 

1“ An Essay Concerning Important Physical Features Exhibited in the Valley of 
the Minnesota River,” 1874-7; and elsewhere. 


2“ Tertiary History of the Grand Cafion District,” 1882, Chapter IX, and maps 
accompanying. 


364 THE JOURNAL OF GEOLOGY: 


reduced by increase of width and depth; though if (as is prob- 
able) erosion varies more nearly with the weight than the veloc- 
ity, its amount will increase absolutely, and the expanded valley 
will tend in a Stronger degree than that measured by the ratio 
of the inverse volumes to assume the general form characteristic 
of contracted glacial gorges. As in the contracted gorge, too, 
lateral effectiveness will remain predominant; but the effective 
energy of the glacier will be mainly concentrated upon the ob- 
structive angles, spurs, and cusps of the irregular water-carved 
walls, and the removal of these and the rounding out of the am- 
phitheatre will be in the first work of the glacier. Again, the 
partial rigidity of the ice-mass will lead to culmination of pres- 
sure about the distal extremity of the amphitheatre, and to 
consequent extension of its boundaries beyond the confluence of 
the tributary by which its water-fashioned prototype was origin- 
ated. 

It follows that glaciated amphitheatres may be merely water- 
carved valley expansions modified by temporary ice-action into 
regularity of contour (as are, for instance, those of the Faerée 
Islands" ), and that they do not necessarily argue profound glacial 
erosion. 


Wal 


Summarizing the chief effects of the several agencies involved 
in the development or the characteristic features of glacial 
cafions, it appears that temporary occupancy of a typical water- 
cut cafion by glacier ice will (1) increase the width, (2) change 
the V to a U cross-profile, (3) cut off the terminal portions 
of tributary cafions, and thus relatively elevate their embouch- 
ures, (4) intensify certain irregularities of gradient in the cafion- 
bottom, (5) excavate rock-basins, (6) develop amphitheatres, 
and, in general, transform such cafion into an equally typical 
glacial cafon. It follows that these features do not necessarily 
imply extensive glacial excavation or indicate that glaciers are 
superlatively energetic engines of erosion. 


W J McGee. 
tJ. GEIKIE, “ Geology of the Faerde Islands,” Trans. Roy. Soc., Edin., 1882. 


HOSS RU NNUSe Ase AN TAID LO) GROLOGY: 


Paleobotany, together with all the other branches of paleon- 
tology, admits of subdivision into two lines, or fields of study— 
the biological and the geological—depending upon the promi- 
nence that is given to the one or the other of these subjects. 
The biological study concerns itself with the evolution of the 
vegetable kingdom, that is, with the tracing of the lines of 
descent through which the living flora has been developed. The 
geological side of paleobotany has two phases, one of which 
concerns itself with the associations, time relations, and distribu- 
tion of the plant forms which constitute the successive floras of 
the geological ages and form an important element in the life ~ 
history of the earth, while the other is concerned principally with 
the use of fossil plants as stratigraphic marks, but also with any aid 
that may be rendered in elucidating the many intricate problems 
which geology presents. The latter, or geological aspect, is 
almost exclusively the phase of the subject to which the present 
paper is devoted. 

Before passing to an elaboration of the claims that paleo- 
botany may have as an aid to geology, it may not be out of 
place to call attention to the fact that the successful use of 
fossils as stratigraphic marks is, or at least may be, entirely 
independent of their correct biological interpretation. It makes 
not the slightest difference to the stratigraphic geologist whether 
the fossils upon which he most relies are named at all, so long 
as their horizon is known and they are clearly defined and 
capable of recognition under any and all conditionsss hey, 
might almost as well be referred to by number as by name, 
although, of course, every paleontologist seeks to interpret to 
the best of his knowledge the fossils that he studies. He 
may, probably often does, make mistakes in his attempts to 

365 


366 THE JOURNAL OF GEOLOGY. 


understand them, but from the very nature of the case this 
must be so. They must all be studied in the light of recent 
forms, which, in the case of wholly extinct groups, is a matter 
of great difficulty. 

On the other hand, to the historical geologist who makes use 
of fossils in unravelling the succession of geological events, the 
correct biological identification is of the greatest importance, for 
upon this rests his interpretation of the succession of faunas and 
floras that have inhabited the globe. These principles are 
tersely stated by Dr. C. A. White in one of his essays on ‘The 
Relation of Biology to Geological Investigation.”* He says: 
“Tf fossils were to be treated only as mere tokens of the 
respective formations in which they are found, their biological 
classification would be a matter of little consequence, but their 
broad signification in historical geology, as well as in systematic 
biology, renders it necessary that they should be classified as 
nearly as possible in the same manner that living animals and 
plants are classified.” 


PRINCIPLES OF PALEOBOTANY. 


There are certain broad, fundamental principles upon which 
the science of paleobotany rests. Some of these are so simple 
as to be almost axiomatic, while others are less evident and have 
only recently been recognized. It has been disregard of these 
principles that, in the past, has often brought paleobotany into 
disrepute. Each of the departments upon which geology calls 
for aid has to acknowledge limitations, and so paleobotany has 
bounds beyond which it can not be legitimately asked to go. But 
it is confidently predicted that when the evidence has been 
sifted, and the limitations, as well as the just claims, have been 
properly adjusted, the evidence derived from fossil plants 
will be as reliable as that supplied by other branches of 
paleontology. 

One of the most important principles has been admirably 


«Ann. Rept. U. S. National Museum, 1892, p. 261. 


LOSSIL PLANL SAS AN AID TO GEOLOGY. 367 


expressed by Professor Ward.t It is that ‘Great types of 
vegetation are characteristic of great epochs of geology, and it 
is impossible for the types of one epoch to occur in another.” 
For example, the presence of a dicotyledonous leaf, no matter 
how fragmentary, is proof positive that the stratum containing it 
is Mesozoic dr younger. It can not possibly be older. Again, 
the presence of a single scar of Lepidodendron or Sigillaria, 
when not in-redeposited strata, is just as strong evidence that 
they came from a Paleozoic horizon, since not a single specimen 
has ever been found later than the Permian. 

The application of this principle is often of the greatest aid 
in geology, for, as frequently happens, the strata of a region 
have been much displaced and distorted, and it is no uncommon 
thing to find Paleozoic rocks occupying the positions that should 
seemingly, normally be taken by Cretaceous or Tertiary strata. 
The stratigraphy may be so exceedingly complicated as to render 
it quite impossible to distinguish Paleozoic from Mesozoic strata. 
Nor can petrography be always depended upon to supply dis- 
tinguishing marks. In such cases, which are by no means purely 
hypothetical, a single fossil plant may serve to set at rest all 
possibility of dispute. 

An example of this kind is furnished by the well-known case 
of the beds of Chardonet in France, “studied by Elie de Beau- 
mont in 1828 and positively referred to the Mesozoic, but in 
which fossil plants of the genera Calamites, Sigillaria and Lepido- 
dendron were identified by Brongniart.”? At that time the 
principle under discussion had not been recognized and Bron- 
gniart was “inclined to admit’ that these genera might have 
occurred in the Mesozoic, although long before his death he 
recognized it and realized that the genera indicated beyond 
question a Paleozoic age. 

Another important principle, bearing upon the limitations of 
paleobotany, is what has been called the law of homotaxis. 

t Principles and Methods of Geologic Correlation by means of Fossil Plants. Am. 
Geol., Vol. IX., 1892, p. 36. 

2 Ward, l.c. 


368 THE JOURNAL OF GEOLOGY. 


As long ago as 1853 Pictet, in his then celebrated Tvrazté de 
FPaléontologie, presented a number of general principles, among 
them being one, the so-called eighth law, which bears directly 
upon the present question. It is as follows: ‘‘Contemporaneous 
deposits, or those formed at the same epoch, contain identical 
fossils. Conversely: deposits which contain identical fossils are 
contemporaneous.”” This was modified by Schimper, the cele- 
brated French paleobotanist, who added that deposits ‘formed 
at the same epoch, contain floras, if not completely identical, at 
least homologous, and consequently deposits that contain iden- 
tical or homologous floras are contemporaneous.” But Huxley 
appears to have been the first (1862) to formulate clearly the 
objections to this law. He pointed out that while the succes- 
sion of life in widely separated localities may be shown to have 
been similar, it by no means follows that the identical elements 
in these widely separated localities were strictly contemporane- 
ous. To this he applied the term /omotaxis, which implies that 
the plants and animals of widely separated places may have 
had practically the same process of development or succession, 
yet when the element of time is considered they may have been 
far from identical. As an example it may be mentioned that 
the most abundant and typical genus of plants in the Carbonifer- 
ous rocks of Australia and Tasmania is Glossopteris, a genus 
which is not represented in rocks of similar age in Europe, but 
occurs in Upper Mesozoic beds of that region. 

This, it will be readily understood, applies to localities widely 
separated, as for example between continents that are not inti- 
mately connected, or that are now and have been for a long 
geological period separated by insurmountable barriers to immi- 
gration, such as oceans and mountain chains. The plants origin- 
ating within a given area or the ones inhabiting a locality adapt 
themselves to the environment, and these can only extend their 
distribution readily to areas in which the conditions are similar. 
Hence if the particular locality in which a species has been 
developed is separated from other areas, perhaps as well suited 

tTraité de Pal. Vég., Vol. I., 1869, p. 100. 


JROSSIOL, JPILAIW TES. AUS) AUN ZUG) TIO) CIS OVGOUG IZ. 369 


to its growth, by a natural barrier such as a lofty, unbroken 
mountain chain or a broad expanse of water, the chances are 
against the species finding its way quickly to the remote areas. 
As an example of this may be cited the flora of the Hawaiian 
Islands. This flora, exclusive of the species introduced since 
the discovery of the Islands by Cooke in 1779, embraces 860 
species of phanerogams and vascular cryptogams. Of this num- 
ber no less than 653, or 75.93 per cent. are endemic or peculiar 
to the Islands. On account of the vast expanse of the Pacific 
by which the Hawaiian Islands are separated from the nearest 
land, the flora has been unable to extend its distribution. 

It is but reasonable to suppose that similar conditions existed 
in past geologic ages, but by the obliteration of barriers, such as 
the shallowing of the water or emergence of direct land connec- 
tion, the plants may have been enabled to invade new territory, 
and thus extend from area to area or from continent to conti- 
nent. If now an examination is made of the remains of vegeta- 
tion in two or several widely separated areas, the succession will 
be found to have been the same, but they may not have been 
strictly contemporaneous. 

What now is the deduction to be made since the formulation 
of this principle regarding the value of paleontologic evidence? 
Does it immediately follow that all correlations based upon sim- 
ilarity of fossil remains fall to the ground? By no means. It 
has simply introduced an additional element of caution into the 
problem of correlation between widely separated areas. And 
even here it has been, and must continue to be, of the greatest 
importance, for, as Professor Ward has well said,* ‘‘What we 
possess is the general fact that a similar flora once existed in 
two parts of the world very widely separated, and until some 
other facts are discovered which complicate and vitiate such a 
conclusion, it is both safe and useful for the geologist to regard 
the two deposits as belonging to the same geologic age. There 
are certain limitations within which this must be true, and when 
these limitations are recognized the paleontologist may as safely 

= N0C, Gitin ]Ds Ao 


370 THE JOURNAL OF GEOLOGY: 


draw his conclusions as he could before the law of homotaxis 
had been formulated.” 

Thus, while admitting the possibility of homotaxial relations 
existing between the floras of widely separated areas, certain cor- 
relations, on the basis of simultaneity, of extensive series of beds 
in different countries, have stood the test of time. On this sub- 
ject Sir William Dawson has given important evidence. He 
says: ‘I desire, however, under this head, to affirm my convic- 
tion that, with reference to the Erian and Carboniferous floras 
of North America and Europe, the doctrine of ‘homotaxis,’ as 
distinct from actual contemporaneity, has no place. The suc- 
cession of formations in the Palzeozoic period evidences a similar 
series of physical phenomena on the grandest scale throughout 
the northern hemisphere. The succession of marine animals 
implies the continuity of the sea-bottoms on which they lived. 
The headquarters of the Erian flora in North America and 
Europe must have been in connected or adjoining areas in the 
North Atlantic. The similarity of the Carboniferous flora on 
the two sides of the Atlantic, and the great number of identical 
species, proves a still closer connection in that period. These 
coincidences are too extensive and too frequently repeated to 
be the result of any accident of similar sequence at different 
times, and this more especially as they extend to the more mi- 
nute differences in the features of each period, as, for instance, 
the floras of the Lower and Upper Devonian, and Lower, Middle, 
and Upper Carboniferous.” 


USE OF FOSSIL PLANTS IN RESTRICTED AREAS. 


Turning now from the correlation of strata in widely separated 
localities, we come to that part of the field in which geology is 
likely to receive its most valuable aid from paleobotany, viz. : 
the identification of horizons and their correlation within 
restricted areas. While the phase of the subject which has just 
been discussed may be of much importance when the final 
volume of the geology of the world comes to be written, it can 


* Geological History of Plants, p. 262. 


FOSSIL PLANTS AS AN AID TO GEOLOGY. evil 


never, if we are to judge by the recent trend of attempts at wide- 
spread correlation, hold the position of importance that correla- 
tion within circumscribed areas does. The minor subdivisions of 
the geological time-standard established for Europe, for example, 
is found to be of only limited application in North America, and 
attempts to bring them into complete harmony are little short of 
wasted energy. But with limited or natural areas the case is far 
different. 

Organic remains are unquestionably of first importance in 
identifying formations. The study of the mineral composition 
and lithqlogical characteristics of formations must be abandoned 
as the sole means necessary for their identification. Recourse 
must be had to the fossils to set the stratigraphist aright, for as 
Professor J. W. Judd has said,? ‘We still regard fossils as the 
‘medals of creation,’ and certain types of life we take to be as 
truly characteristic of definite periods as the coins which bear the 
image and superscription of a Roman emperor or of a Saxon 
king.” Of thé various kinds of such remains fossil plants occupy 
relatively as important a position as those afforded by most of 
the other biological groups. 

It is by no means uncommon to find that fossil plants are 
almost the only organic remains present ina formation, but if 
they are not, the evidence they afford, when properly interpreted, 
confirms that obtained from other groups of organic life, as the 
following examples will show. 

As an illustration of the first mentioned condition, viz. : that 
in which plants only are present in numbers sufficient to entitle 
them to exclusive consideration, the Dakota group offers an 
exceptionally fine example. This formation is four or five hun- 
dred miles wide, more than a thousand miles long and of consid- 
erable thickness, yet not a single vertebrate fossil, and hardly ten 
species of invertebrates have thus far been detected throughout its 
vast extent. The Dakota flora, however, is one of the most exten- 
sive and thoroughly known fossil floras. According to Lesquereux’ 

tNature, Vol. XXXVIL., 1888, p. 426. 
2 Flora of the Dakota Group, p. 14. 


372 THE JOURNAL OF GEOLOGY. 


460 species have been described from this formation, of which 
number no less than 394 are peculiar, that is, have never yet 
been found outside of it. A very large number of these plants 
are so characteristic that their discovery in strata of unknown age 
would settle at once their reference to this horizon. An illustra- 
tion of this is just at hand. A single dicotyledonous leaf was 
some time ago described,’ under the name of Sterculia Draket, 
from the upper sandstone of the Tucumcari beds near Big 
Tucumcari Mountain, New Mexico. This plant has lately” been 
referred to as the only dicotyledon known from the Trinity beds 
of the Comanche series, a reference that is, so far as we know, 
highly improbable, for Fontaine, in his descriptions of all of the 
plants now known from these beds? finds no trace of dicotyledons. 
A glance at the figure of the Tucumcari plant suffices to show that it 
is Sterculia Snowii, a well-known, very abundant, and characteristic 
plant of the Dakota group. This leaf, together with what is now 
known of the position of the rocks containing it, is amply suffi- 
cient to settle the age of this portion of the Tucumcari sandstone, 
a conclusion agreeing perfectly with the results several times set 
forth by Professor R.T. Hill from stratigraphic and paleonto- 
logical grounds. The Potomac formation furnishes a parallel 
example. This series of beds, extending in almost unbroken 
line from New Jersey to Alabama, contains a known flora of 737 
species, over 80 per cent. of which are peculiar. 

An example of the complete accord existing between fossil | 
plants and other organic remains in determining age is offered by 
the Trinity Division of the Comanche Series of Texas, the flora of 
which, so far as known, has recently been worked out by Fontaine.‘ 
The particular beds in this series, from which the plants came, have 
been named the Glen Rose or alternating strata, by Professor 
R. T. Hill, and their age determined by marine invertebrates, as 
Neocomian or basal Cretaceous. The flora consists of twenty- 


*Geol. Survey of Texas, 3d Ann. Rept., 1891, p. 210. 

? Am. Geol., Vol. XII., 1893, p. 327. 

3 Proc. U. S. National Museum, Vol. XVI., 1893, p. 261-282. 
Op. cit., p. 281. 


PHOSSVUL, IPILAUINIGS AlS) AUN AIUD) TRO) (GIR OILOG YZ. 373 


three species of plants characteristic of the lower Cretaceous, 
and appears to find its closest resemblance in the older portion 
of the lower Potomac. Professor Fontaine’s results are summed 
up as follows: ‘The Glen Rose or alternating strata, in which 
the fossil plants are found, contain an abundant marine fauna, 
from the evidence of which Professor Hill had concluded that 
its age was Neocomian or basal Cretaceous. No fossil plants 
had hitherto been found in the Comanche series, and the evidence 
of its age was derived wholly from the animal remains. The 
discovery of plants in it was, then, of special importance, for it 
enabled us to compare the evidence of the plant-life with that of 
the animal life. It is interesting to find so close an agreement. 
This agreement adds one more proof of the value of fossil floras 
in fixing the age of the strata in which they are found.” 

The age of the strata exposed at Gay Head, on the western 
end of Martha’s Vineyard, has been the subject of discussion 
and speculation by geologists for nearly or quite a hundred years, 
and the question has only recently been settled. In general the 
strata have been correlated with the similarly appearing strata of 
Alum Bay in the Isle of Wight, the position of which is fixed as 
middle Eocene. It is true that certain Cretaceous shells had 
been found, but they were not in place, and so intermingled with 
recent forms, that it was concluded that the age could hardly be 
other than lower or middle Tertiary. As late as 1889 Professor 
N. S. Shaler* decided, upon purely stratigraphic grounds, that 
“this part of the Tertiary series is certainly of later Miocene or 
Pliocene age. 

In 1890 Mr. David White visited Martha’s Vineyard, and was 
fortunate enough to find and collect a considerable series of fossil 
plants from the strata in question. The results of this study? 
showed beyond all doubt that they were of Cretaceous age, 
many being identical with the plants of the Amboy clays of New 
Jetseye ihe Gay lead flora,” Mr) White concludes, ““indi- 


*Seventh Annual Report U. S. Geol. Survey, 1885-6, p. 332. 
2Cf. Am. Jour. Sci., Vol. XXXIX., 1890, pp. 93-101. 


374 THE JOURNAL OF GEOLOGY. 


cates an age certainly Cretaceous, and probably middle Cre- 
taceousin 

Here, then, is an example of the value of a few fossil plants 
in determining the age of a series of beds where a hundred years 
of study from the stratigraphic side had failed to accomplish 
conclusive results. 

The flora of the so-called Laramie beds of the Rocky Moun- 
tain region has also been the subject of much discussion and 
controversy. By certain of the older writers it was referred to 
the Tertiary, by others to the Upper Cretaceous. Recent investi- 
gation has shown, however, that several distinct horizons were 
embraced in what has been known as the Laramie. The tend- 
ency appears to be to restrict the term ‘‘Laramie,” at least in 
the Colorado district, to the lower or older beds, and accordingly 
the Post Laramie beds have been differentiated and given inde- 
pendent names. As fossil plants are the most abundant organic 
remains present in this series of strata, their bearing on the ques- 
tion of the age and differentiation of the beds is important. No 
dependence can be placed on the earlier determinations of the dis- 
tribution of the plants, for the reason that the different horizons 
had not then been distinguished, and the plants are often recorded 
from a locality at which several of the horizons are present and 
plant-bearing. It has been necessary to go over all the original 
material and determine by studying the matrix, and by duplicate 
collections, the actual horizon to which they belong. In this 
way the status of 285 species now known to occur in these beds 
has been settled. In Colorado and New Mexico, the only area 
in which the interrelations have yet been worked out, it appears 
that there is a flora of 165 species, of which number 62 belong to 
the true Laramie and 103 to the Denver beds, and with only 7 
species common to both. This proves beyond question that the 
Laramie and Denver beds are distinct, and that they possess, in 
certain clearly defined species of fossil plants, readily recogniz- 
able stratigraphic marks. 

The deductions made from this datum point, viz.: the 
thorough study of the flora of the Colorado Laramie and allied. 


HOS SUES ZANE SIEA SA NieALD LTO'GHROLOGY, 375 


formations, are already important. Of these two or three 
examples may be cited. 

The Post-Laramie beds of Middle Park, Colorado, have been 
made the subject of an investigation by Mr. Whitman Cross. 
After reviewing historically the opinions of various writers as to 
the age of these beds, he discusses exhaustively the results of 
recent work in this field. He reviews the fossil flora at length, 
correcting many obvious errors of locality and horizon into 
which the early collections had fallen, and finally presents a 
revised list of the plants known certainly to have come from the 
Middle Park beds. In the light of the revisions of the Laramie 
and Denver floras, nearly 75 per cent. of the species enumerated 
in this list are found to be common to the Denver beds. The 
complete agreement of the paleobotanical with the other geol- 
ogical evidences is well shown in conclusions of Mr. Cross, 
which are as follows: ‘‘ The unconformable relationships, lithol- 
ogical constitution, and fossil flora all indicate the equivalence of 
the Middle Park and Denver beds. No evidence seems to 
indicate any other correlation.” * 

The Laramie and Post-Laramie beds of Montana have been 
studied by Mr. W. H. Weed.? His paper gives an account of a 
‘series of beds heretofore embraced within the Laramie, and 
covering the greater portion of the State of Montana east of the 
Rocky Mountains. It is shown stratigraphically that the thick- 
ness of some 13,000 feet of strata belong to three formations : 
the Laramie, the overlying Livingston, and the higher Fort 
Union beds. 

Fossil plants occur in all three of these formations, and from 
their study it is made clear that the Livingston beds occupy the 
same position in Montana, with reference to the Laramie, as do 
the Denver beds in Colorado. Of 22 species of plants found in 
the Livingston beds no jess than 17 are found either exclusively 
in the Denver, or have their greatest development in this 
formation. 


*Proc. Colorado Scientific Soc., 1892, p. 26 of reprint. 
? Bull. U. S. Geol. Survey, No. 105. 


370 THE JOURNAL OF GEOLOGY. 


Large numbers of huge vertebrate remains, only known from 
“The Laramie of Wyoming,” fortunately have fragments of 
fossil plants adhering to them, from the study of which impor- 
tant light will be thrown on the age of the beds in which they are 
contained. 

Along the Missouri river in the vicinity of Great Falls, Mon- 
tana, there is exposed a considerable thickness of mainly brown, 
sandstone rocks. They have been eroded by the river into more 
or less of a cafion, and are the material in which the falls have 
been developed. From their lithologic appearance, but mainly 
upon stratigraphic grounds, these rocks have been referred by 
geologists to the Dakota group. On going down the river they 
disappear under the Fort Benton shales, and are consequently in 
the stratigraphic position of the Dakota, but the recent discovery 
of plant-beds near Great Falls has shown the impossibility of 
such reference. The plants are typically lower Cretaceous, and 
have been positively identified by Newberry with the Kootanie 
of Canada. By this a part at least of the so-called Dakota goes 
to the lowest Cretaceous. 

In a similar way a part of the supposed Dakota of the Black 
Hills has been shown by Professor Ward,’ purely on paleo- 
botanical evidence, to belong to the lower Cretaceous. 

The Foreman beds in the Taylorville region, Plumas county, 
California, were determined to be of Rhetic age from the fossil 
plants, a determination agreeing perfectly with the stratigraphy.’ 

The copper mines near Abiquiu, New Mexico, were identi- 
fied as Triassic by the plants found in and about the roof of the 
openings.3 

The employment of fossil plants in practical mining exploita- 
tion is well shown by the results obtained by Grand’ Eury and 
Zeiller in Southern France. 

In the Department of Gard the mining of coal is one of 


tJournal of Geology, Vol. II., No. 3, pp. 250-266. 
2 DILLER : Bull. Geol. Soc. Am., Vol. 3, p. 373. 


3FONTAINE & KNOWLTON: Proc. U.S. Nat. Mus., Vol. XIII., 1890, p. 282-285. 
NEWBERRY: Rep. Expl. Ex. in 1859 under Macomb. Wash., 1876, p. 140. 


FOSSIL PLANTS AS AN AID TO GEOLOGY. A077 


the most important industries. In this district there are a num- 
ber of veins of workable coal which have been formed at 
different epochs. These veins are separated from each other by 
barren strata of varying thickness, and are always accompanied 
by certain characteristic plants, especially ferns and allied forms. 

In the valley of the Grand’ Combe there are a number of 
coal openings, among which may be more especially distin- 
guished those of the Sainte Barbe and Grand’ Combe. M. 
Zeiller, the engineer-in-chief of the mines, from a study of the 
fossil plants which accompany the two layers, determined that 
the first deposit, viz.: that of Sainte Barbe, was older than the 
other. With this knowledge in his possession, M. Zeiller did 
not hesitate to counsel the company that by sinking a shaft at a 
place called Richard, just outside of the valley of the Grand’ 
Combe, they would reach a new seam of coal corresponding to 
the Sainte Barbe. The shaft was sunk for 400 meters, but as 
only barren strata were encountered it was abandoned, and it was 
reserved for Grand’ Eury to prove the correctness of Zeiller’s 
prediction. 

Grand’ Eury, in a general study of the coal basin of Gard 
by means of fossil plants, determined that the coal of Sainte 
Barbe was deposited at the same epoch as that of Besseges, from 
the fact that the same plants occurred at both localities. In the 
same manner he proved that the coal of Grand’ Combe was of the 
same age as that of Gangiéres, but he also found that between 
the beds of Bességes and Gangiéres there was a barren series of 
strata approximating 600 meters in thickness. It therefore 
became evident that the shaft at Richard had been abandoned too 
hastily, and work was again prosecuted, and at a depth of 731 
meters the vein of coal, 4.80 meters thick, corresponding to the 
Sainte Barbe, was reached. 


STUDY OF FOSSIL PLANTS BY MEANS OF INTERNAL STRUCTURE. 


By far the larger proportion of fossil plants are preserved in 
the form of impressions or casts of leaves, fruits, stems, etc., only 
comparatively few having the internal structure so preserved as 


378 THE JOURNAL OF GEOLOGY. 


to admit of their study under the microscope. The parts usu- 
ally exhibiting internal structure are stems, branches, roots, and 
other normally hard organs, yet in exceptional cases every part 
of the plant, including the leaves, buds, and flowers, are so per- 
fectly preserved that they may be as successfully studied as 
though living. An example of this kind is afforded by the Car- 
boniferous groups of Cordaites, found in a state of silicification 
in central France. 

Plants that are so preserved as to retain their internal struc- 
ture, admit of closer study and characterization than is usually 
attained for other plant organs. So valuable is this method that 
Professor W. C. Williamson, the distinguished English paleo- 
botanist, was led to say* “that no determinations respecting 
fossil plants can have much absolute value save such as rest 
upon internal organization ; that is the basis upon which all sci- 
entific recent botany rests, and no mere external appearances can 
outweigh the positive testimony of organization in fossil types.” 
Therefore, when it is possible to obtain plant remains with the 
internal structure preserved, it may be safely set down that they 
will afford valuable and reliable data for stratigraphic identifica- 
tion. 

The study of the internal structure of fossil plants is yet 
young in North America, and while a broad field remains for 
future investigation, enough has already been accomplished to 
show its value. A few examples may be cited: 

In 1888, Avaucarioxylon Arizonicum was described from the 
Trias (Shinarump group of Powell) of New Mexico. The same 
species has been found characteristic of the Trias of North 
Carolina? and of the copper mines near Abiquiu, New Mexico.3 

In his paper on the geology of Skunnemunk Mountain, 
Orange county, New York,‘ Professor C. S. Prosser relies upon 

«On the Organization of the Fossil Plants of the Coal Measures. Roy.Soc., Lon- 
don. Phil. Trans.. Vol. 161; 1871; p. 492. 

*? RUSSELL: The Newark System, p. 29. 

3 FONTAINE and KNOWLTON: Notes on Triassic plants from New Mexico. Prec. 
U.S. Nat. Mus., Vol. XIII, 1890, pp 281-285. 

4Trans. N. Y. Academy Science, Vol. XI., June, 1892. 


FOSSIL PLANTS AS AN AID TO GEOLOGY. 379 


the fossil plants, especially NMematophyton crassum known from 
the study of its internal structure, to prove the Middle Devonian 
age of that part of the geological section. 

Certain well-defined species of fossil wood are characteristic 
of particular horizons, as for example Cordaites Ouangondianus 
(Dn.) Gépp., which is confined to the Middle Erian (Devonian); 
C. Halli (Dn.) Kn., and C. Newberryi (Dn.) Kn., are confined to 
the Hamilton Group; Dadoxylon annulatum Dn., found only in 
the middle coal-measures, etc. 


SUBSIDIARY USE OF FOSSIL PLANTS. 


Among the many relatively subsidiary problems connected 
with the application of paleobotany to geology, the use of fossil 
plants as tests of past climate occupies an important place. 
Plants are unable to migrate like animals when the temperature 
of their habitat becomes unfavorable, and they must either give 
way, or adapt themselves gradually to the changed conditions 
of environment. Hence, fossil plants have always been accorded 
first place as indices of past climates. ‘‘ They are,’ as Dr. Asa 
Gray has said, ‘“‘ the thermometers of the ages, by which climatic 
extremes and climate in general through long periods are best 
measured.” 7 

The wide geographical distribution and similarity of appear- 
ance of Paleozoic plants, especially coal-measure plants, argues 
beyond question a uniformity of climatic conditions. The 
absence of rings of growth in the Carboniferous conifers shows, 
as long ago pointed out by Witham, that the seasons, if such 
they could have been called, were either absent or not abrupt, 
and it is not until the Trias is reached that the clearly defined 
rings of growth bear indisputable evidence of the existence of 
seasons. 

‘Heer, as a result of his examination of the Swiss Tertiary 
plant-beds, is led to the interesting conclusion that in certain 
cases it is possible to detect the regular recurrence of seasons 
by the constant association in the same strata of fruits or leaves 


*The Nation, No. 742, September 18, 1879. 


380 THE JOURNAL OF GEOLOGY. 


of plants whose living representatives are known to agree closely 
in their period of vegetation.’”* 

Fossil plants may also, in certain cases, be used to indicate 
the character of the water in which the depcsits were laid down. 
Thus, the finding of an abundance of marine diatoms in an undis- 
turbed formation is proof that they were deposited in salt water, 
and the finding of diatoms only known in connection with hot 
springs is equal proof of former thermal activity. As an exam- 
ple of the last may be mentioned the finding of a large number 
of species of diatoms in beds of infusorial earth in Utah that are 
now found living in a hot spring (temperature 163° F.) in 
Pueblo Valley, Humbolt County, Nevada, showing that the fossil 
specimens must have been accumulated in a hot lake of about 
the same temperature.’ 

It is quite commonly argued that during Carboniferous time 
there was present such a large amount of carbon-dioxide that it 
produced athick veil, hiding or at least largely obscuring the direct 
sunlight. This extreme view is not wholly sustained by fossil plants, 
for the presence of strongly developed palisade parenchyma in 
certain leaves, as in Cordaites and many ferns, which can only 
be formed in direct sunlight, shows conclusively that there 
must have been at least gleams of sunlight penetrating the so- 
called veil. 


LEGITIMATE FIELD OF PALEOBOTANY. 


Before leaving the subject it may be well to point out some 
of the responsibilities resting with the geologist who would avail 
himself of paleobotanical aid in the determination of horizons. 
In the first place, if it is worth while to ask an opinion of the 
paleobotanist, it is surely worth while for the geologist to spend 
time enough when making the collection he would submit, to 
procure at least a fair representation of the fossil flora of that 
horizon. To expect the paleobotanist to unravel a stratigraphic 
problem that has perhaps puzzled the trained stratigrapher and 


tA.C. Seward. Fossil Plants as Tests of Climate, p. 20. 


2 Am. Journ. Sci., 3d ser., Vol. IV., 1872, p. 148. 


POSSIE PEANDS AS AN AID TO. GEOLOGY. 381 


petrographer, by the examination of a mere handful of speci- 
mens gathered hastily as a “ last thought,” is asking too much! 
There is a limit to what can legitimately be expected of paleo- 
botany, just as there is a limit to all knowledge. 

Again, it has frequently been a practice among geologists to 
submit a collection of fossil plants without indication of the 
specific information desired or even of the locality whence the 
specimens came. This is done presumably with the idea that the 
paleobotanist, being unembarrased with previous information, 
would be the better able to give an unbiased opinion. This 
again is wrong, and under such circumstances the paleobotanist 
would be amply justified in declining to express an opinion. 
Unless he can be placed in possession of all the information known 
to the geologist, or, what is better, have an opportunity of exam- 
ining the relations of the horizons himself, he should hesitate 
before passing judgment. Of course, as pointed out under the 
discussion of principles, certain broad conclusions may be made 
instantly, such as the presence of dicotyledons proving an upper 
Mesozoic age, or Lepidodendra and Sigillaria arguing a Paleozoic 
age. These, however, are not usually the problems presented, 
but close questions of age, as, for example, the Miocene or 
Pliocene age of the auriferous gravels of California. 

It has been argued by many, especially botanists and geolo- 
gists, that it is undesirable to give names to fragmentary and 
seemingly indeterminable plant remains. When a definite name 
is given it implies, it is argued, a more exact knowledge than is 
often times possessed; a view that in many cases is undoubtedly 
correct. But the name is given, when the fossil cannot be made 
out satisfactorily, for purely practical reasons. It embodies, or 
should, the best possible judgment as to its nature and syste- 
matic position, and serves as a convenient basis of future men- 
tion of it without tedious circumlocution. 

The foregoing examples have been given somewhat in detail, 
for the purpose of showing what has already been done with 
fossil plants, and to indicate the lines along which, it is hoped, 
increased assistance will be rendered geology inthe future. These 


382 THE JOURNAL OF GEOLOGY. 


examples have designedly been confined almost exclusively to 
North America, and while additional ones might have been given 
within this area, but more particularly in other countries, enough 
has been presented to indicate that paleobotany may be relied 
upon to supply a series of stratigraphic marks in every way as 
reliable for the cases they cover as those supplied by any of 
the other branches of paleontology. 
F. H Know trton. 


WAVE-LIKE PROGRESS OF AN EPEIROGENIC 
URE T 


To the ancient Greeks the word epeiros, specially applied to 
the land lying next north, signified also, in general, any mainland 
or continental area, as contrasted with islands or their own 
peninsular country. From this word Gilbert has recently sup- 
plied to our science the terms eperrogeny and epetrogenic, to desig- 
nate the broad movements of uplift and subsidence which affect 
the whole or large parts of continents and of the oceanic basins.’ 
Previously the correlative terms ovogeny and orogenic had come 
into use, denoting the process of formation of mountain ranges 
by folds, faults, upthrusts and overthrusts, affecting compara- 
tively narrow belts and lifting them in great ridges, while the 
epeirogenic movements of the earth’s crust produce and maintain 
the continental plateaus and the broad depressions which are 
covered by the sea. 

During the closing part of the Tertiary era and the present 
Quaternary or Psychozoic era, both epeirogenic and orogenic 
changes have been in progress on many portions of the earth, 
and on a scale of grandeur probably never before surpassed. 
Where these movements have raised continental regions or 
mountain districts to much greater altitudes than they now 
retain, if they were situated within the range of prevailing air 
currents abundantly laden with moisture and were at latitudes 
so far from the equator that the precipitation was chiefly snow 
throughout the year, they became for a time enveloped by ice- 
sheets, which have left the surface strewn with glacial and modi- 
fied drift. Fjords, and now submarine continuations of river 


« Presented before the World’s Congress on Geology, auxiliary with the Columbian 
Exposition, Chicago, August 25, 1893. This paper is an attempt to answer, by a 
definite example, a portion of the inquiries in an editorial of the JOURNAL OF 
GEOLOGY, Vol. 1, page 298, April-May, 1893. 

“Take Bonneville,” Monograph I., U. S. Geological Survey, 1890, p. 340. 

383 


384 THE JOURNAL OF GEOLOGY. 


valleys, attest for the northern two-thirds of North America 
such late Tertiary and Quaternary epeirogenic uplift at least 
2,000 to 3,000 feet above the present height of this continent ; 
for the British Isles, Scandinavia, and probably the greater part 
of Europe, an uplift 1,000 to 4,000 feet higher than now ; and 
for the western side of Africa within a few degrees both north 
and south of the equator, 3,000 to 6,000 feet.* Attending the 
subsidence of these areas, greatly increased altitudes have been 
given by folding, rifts, and upthrusts, to large portions of the 
highest mountain systems of the world, as the Alp-Himalayan 
and Andes-Cordilleran belts.2, The most recent of all mountains, 
excepting volcanic cones, probably is the lofty St. Elias range, 
according to Russell’s observations ; and the belt in which this is 
a part has an extent of two-thirds of the circumference of the 
globe, from Cape Horn to Alaska, the Aleutian Islands, Kamt- 
chatka, the Kuriles, Japan, and the Philippine islands, intersect- 
ing the eastern part of the Alp-Himalayan belt near Krakatoa, 
in the earth’s most volcanic and seismic district. 

The drift-bearing areas in North America, in Europe, and in 
Patagonia, which at the end of their epoch of gradual elevation 
and fjord erosion had become deeply covered by land-ice, sank 
under its weight until] when the ice melted away they mainly 
stood somewhat lower than now. The shores of the sea at that 
time in the St. Lawrence and Ottawa valleys, in the basin of 
lake Champlain, and about Hudson bay, have been again uplifted, 

tJ. W. SPENCER, Bulletin, Geol. Soc. Am., Vol. 1., 1890, pp. 65-70 (also in the 
Geol. Magazine, III., Vol. 7, 1890, pp. 208-212). J. D. Dana, Am. Jour. Sci., IIT., 
Vol. 40, pp. 425-437, Dec., 1890, with an excellent map of the Hudson submarine 
valley and fjord. G. Davipson, Bulletin of the California Academy of Sciences, Vol. 


2, 1887, pp. 265-268. ‘T.F, Jamirson, Geol. Mag., III., Vol. 8, pp. 387-392, Sept., 
1891. J. Y. BUCHANAN, Scottish Geographical Magazine, Vol. 3, 1887, pp. 217-238. 
2H. B. MEpLICOTT and W. T. BLANFORD, Manual of the Geology of India, 
Calcutta, 1879, Part 1., pp. lvi, 372; Part Il., pp. 569-571, 667-669, 672-681. 
J. Le Conve, Am. Jour. Sci., III., Vol. 32, pp. 167-181, Sept. 1886; Bulletin, Geol. 
Soc. Am., Vol. 2, 1891, pp. 323-330; Elements of Geology, third edition, 1891, pp. 
250-266, 589. J. S. Dirier, Eighth An. Rep., U.S. Geol. Survey, for 1886-87, pp. 
426-432; JOURNAL OF GEOLOGY, Vol. 2, pp. 32-54, Jan.—Feb., 1894. I. C. RUSSELL, 
National Geographic Magazine, Vol. 3, 1891, pp. 172, 173. _W. UPHAM, Appalachia, 
Vol. 6, 1891, pp. 191-207 (also in Pop. Sci. Monthly, Vol. 39, pp. 665-678, Sept. 1891). 


WAVE-LIKE PROGRESS OF AN EPEIROGENIC UPLIFT. 385 


but only to a comparatively small amount, from 200 to 500 or 
,600 feet, after the departure of the ice-sheet. In Scandinavia, 
according to the investigations of Baron de Geer, the postglacial 
uplift has varied from a minimum of roo feet or less at the 
southern extremity of Sweden, toa maximum exceeding 1,000 
feet in the central part of the peninsula.’ Likewise in South 
America, along a distance of 1,200 miles, from the Rio Plata to 
Tierra del Fuego, the land has been elevated since its glaciation, 
the general extent of this movement in Patagonia, as observed 
by Darwin, being between 300 and 400 feet.” 
The special case of an epeirogenic movement progressing like 
a wave, which it is the purpose of this paper to consider, is this 
latest, moderate uplift of North America, and especially of its 
central belt comprised in the Mississippi and Nelson river basins, 
from its depression at the close of the Glacial period. While the 
‘ice-sheet was retreating, this great area was rising ds fast as its 
burden was removed. Close upon the wasting ice-border there 
followed a wave of permanent uplift of the land on which it had 
lain. First the loess district along the Mississippi and the upper 
part of this basin were elevated ; next, the southern half of the 
area of the glacial lake Agassiz ; later, its northern half; and last 
of all, the country enclosing Hudson bay, with which also was 
probably associated, as very late in its uplift, the region of the 
great Laurentian lakes, including lake Champlain, and of the 
Ottawa and the St. Lawrence. From south to north and north- 
east the wave of elevation advanced, and, according to Dr. 
Robert Bell, the rise of the land has not yet ceased about James 
and Hudson bays, where, in the central part of the glaciated 
region, we must suppose that the ice-sheet had its greatest 
thickness and was latest represented by lingering remnants. 
Having thus outlined our theme, let us return and look more 
x Bulletin, Geol. Soc. Am., Vol. 3, 1891, pp. 65-68, with map of the late glacial 
marine area in southern Sweden; Proceedings of the Boston Society of Natural 


History, Vol. 25, 1892, pp. 456-461 (also in the Am. Geologist, Vol. 11, pp. 23-29, 
Jan., 1893). 


2 “Voyage of H.M.S. Beagle,” chapter vill. 


336 THE JOURNAL OF GEOLOGY. 


fully at the evidence of this progressive earth movement in the 
chronologic and geographic order of its successive portions. 

Between the chief time of deposition of the Mississippi loess 
and the formation of the prominent moraines east of the Wis- 
consin driftless area, there intervened an uplift of the upper 
Mississippi region to a vertical extent estimated by Chamberlin 
and Salisbury as probably 800 to 1,000 feet. On the western 
portion of the driftless area and southward to the Gulf of Mexico, 
the loess had been spread by very slowly flowing river floods, 
and partly in temporary lakes, due to the greater depression of 
the basin toward the north, while in the opposite direction the 
subsidence was insufficient to carry the low southern part of the 
valley beneath the sea level. The ensuing uplift probably 
scarcely increased the altitude of that southern area about the 
mouth of the Mississippi, but thence it extended northward as a 
differential epeirogenic movement, raising the depressed country 
of the central and northern portions of this great river basin 
several hundred feet. As a result of the changed slope, in the 
former place of the quiet water whose sediment was the loess, 
strong currents, bearing sand and gravel, flowed down the valleys 
from the ice-front when it amassed the moraines mentioned in 
Wisconsin. The duration thus represented has been supposed to 
comprise a long interglacial epoch, but the observations on 
which this belief rests seem to me to admit a different interpre- 
tation. 

On the drift border, in some parts of southern Illinois and 
Indiana, the loess was deposited, according to Salisbury, imme- 
diately after the till which immediately underlies it, and was in 
part contemporaneous with the till. As soon as the ice-sheet 
retired from the positions where this relationship exists, the 
glacial drift was covered by this finer silt of the modified drift 
supplied by streams that flowed from the melting and retreating 
ice.?, In the northeastern part of lowa, McGee similarly finds the 

™“ Preliminary Paper on the Driftless Area of the Upper Mississippi Valley,” 
Seventh An. Rep., U. S. Geol. Survey, for 1884-85, pp. 199-322. 


2“The Geology of Crowley’s Ridge” (1891), Geol. Survey of Arkansas, An. Rep. 
for 1889, Vol. 2, pp. 228, 229. 


WAVE-LIKE PROGRESS OF AN EPEIROGENIC UPLIFT. 387 


loess to have been deposited while the ice-sheet that spread the 
upper portion of the early till was melting away. The very 
remarkable paha of that district, which are eskers of loess, were 
accumulated while the waning ice-sheet walled them in at each 
side.t That the later part of the loess deposition was contem- 
poraneous with the formation of the Altamont moraine, belong- 
ing to the later drift and marking its limits, I ascertained in 
northwestern Iowa, where this moraine along a distance of seventy- 
five miles, from Guthrie county northwestward to Storm Lake, is 
bordered on its west side by an expanse of loess as high as the 
crests of the morainic hills, while its elevation above the expanse 
of till eastward is from fifty to seventy-five feet. During the 
time of deposition of this part of the loess the ice-sheet reached 
to the Altamont moraine and was a barrier preventing the waters 
by which the loess was brought from flowing over the lower area 
of till that reaches thence east to the Des Moines river.? On 
three widely separated tracts the loess, as elsewhere the coarser 
portions of the modified drift forming sand and gravel plains, 
was in progress of deposition upon successive areas as fast as the 
ice-sheet supplying these stratified drift beds receded. Imme- 
diately after the land was bared by the retreat of the ice, and 
even while the ice itself occupied the adjoining land, the loess 
was being laid down, contemporaneous successively with the 
early till on the southern border of the drift, with the till of 
intermediate age in northeastern Iowa, and with the later till 
enclosed by the Altamont moraine. The loess deposition I be- 
lieve to have been mainly continuous, accompanying the gradual 
and widely extended but wavering departure of the ice-sheet 
from its farthest boundary to this outermost of the conspicuous 
morainic belts.3 

_*U.S. Geol. Survey, Eleventh An. Rep. for 1889-90, pp. 435-471. 

?Geol. and Nat. Hist. Survey of Minnesota, Ninth An. Rep. for 1880, pp. 307- 
314, 338. 

3 The interpretation of the loess and glacial history of the Mississippi basin which 
I here present differs widely, it must be acknowledged, from the opinions of Professors 


Chamberlin and Salisbury, and Messrs. McGee and Leverett, to whom we owe so much 
of the critical investigation of this area. These observers have been led by their 


388 WEI, Sf OUMIN AUG (QU, (CIS OUSOG JZ 


_ While the ice was retreating and supplying the loess, the land 
thus uncovered and relieved from the ice weight had been grad- 
ually rising, until it had attained approximately its present height 
in Wisconsin, Iowa, and southern Minnesota, before the formation 
of the moraines. This altitude has endured, excepting minor 


studies to conclude that between the deposition of the early till in southeastern Illinois, 
with its accompanying loess, and that of the till and attendant paha or eskers of loess 
in northeastern Iowa, there intervened a very long and diversified history of glacial 
recessions and re-advances, including at least one prolonged interglacial epoch. A 
summary of these views in relation to the glacial succession in Ohio is well stated by 
Mr. Frank Leverett in this JOURNAL OF GEOLOGY, Vol. 1, pages 129-146, Feb.-March, 
1893. From my early study, “Modified Drift in New Hampshire” (Geol. of N. H., 
Vol. 3.,1878, chapter i., pp. 3-176, with maps and sections), and from my later work on 
the Glacial Lake Agassiz, 1 am strongly impressed with the conviction that the depo- 
sition and ensuing erosion of the drift, both till and stratified beds, as the loess, went 
forward very rapidly. What these authors have ascribed to interglacial epochs, one or 
“more of them of great length, seems to me to be more probably referable to geologically 
very short stages of fluctuation of the mainly waning ice-sheet. 

Professor Salisbury, in the report cited, shows that there were two successive de- 
posits of till, and a corresponding division of the loess, on and near to the boundaries 
of the drift; these seem to me probably due to two closely consecutive stages of ice 
advance, instead of the long time interval which he thinks to be indicated. Again, in 
the report on northeastern Iowa, to which reference was given, Mr. McGee clearly 
shows, chiefly by the forest bed intercalated between two sheets of till, that likewise 
there the ice advanced twice, with a considerable intervening time, which he supposes 
to have been far longer than the Postglacial epoch. To my mind, however, the forest- 
covered borders of the’Malaspina glacier or ice-sheet in Alaska leave no doubt that 
forest beds enclosed in till may be due to oscillations of the ice-front within distances 
of no more than a few miles or even less than one mile, and that they may have 
required no longer interval than a few tens of years or at most a century, sufficient for 
the forest growth, between the times of ice retreat and re-advance. 

When the depression of the ice-loaded land brought it down to so low altitude 
that the borders of the ice-sheet began to be melted more rapidly than they received 
increase by snowfall and onflow from the thicker central portion of the ice, a general 
recession of the glacial margin ensued. On the southern part of the drift in the 
Mississippi basin no continuous moraines were accumulated, and I attribute their 
absence principally to the attenuated condition of the ice there and its lack of a steep 
border. During the glacial retreat, wherever the wavering climate caused the mainly 
waning ice-border to remain nearly stationary during several years the vigorous outflow 
of the ice to its then steep frontal slope brought much drift, forming belts of irregular 
morainic hills and ridges, and leaving many hollows which enclose lakes. The fluctu- 
ations of the general glacial retreat seem to me to have been due principally to varia- 
tions of snowfall, some long terms of years having much snow and prevailingly cool 
temperature, therefore allowing considerable glacial re-advance, while for the greater 
part other series of years favored rapid melting and retreat. 


WAVE-LIKE PROGRESS OF AN EPEIROGENIC UPLIFT. 389 


and unimportant oscillations, from that time until now. The 
beginning or earliest known stage of the progressive elevatory 
wave probably thus raised the northern half of the Mississippi 
basin to a variable amount ranging from 100 feet or less to 500 
feet or more. It was practically completed, for this area, previous 
to the accumulation of the outer and earlier moraines in the series 
of many which mark pauses in the further recession of the ice- 
sheet. Thenceforward the glacial melting appears to have been 
more rapid than before, giving to the ice steeper frontal gradients 
whereby its drift was amassed more commonly in hills, ridges, 
and lake-enclosing hollows, and especially in the very irregularly 
knolly and hilly moraine belts. 

The rapidity of the glacial recession and of this ensuing 
epeirogenic uplift in its wave-like advance upon the area of the 
glacial Lake Agassiz, extending nearly 700 miles from south to 
north in the basin of the Red river and of Lake Winnipeg, sur- 
passes all previous knowledge in what it reveals concerning the 
mobility of the earth’s crust. The postglacial duration of Lake 
Michigan and its companion great lakes of the St. Lawrence 
has been shown, by numerous independent but well agreeing 
observations and estimates, to be no longer than 6,000 to 10,000 
years. Now the amount of wave erosion on the shores of Lake 
Michigan and the resulting accumulation of beach sand, heaped 
into dunes upon large areas about the south end of the lake, 
MUSEMEXCECG, DV a) rato OL NO 21 Of 20.41, the cormesponding 
wave action in its total amount at all the successive levels held 
by Lake Agassiz during its history, which accordingly must be 
_ comprised within some such time as 1,000 years or perhaps less." 
During this geologically very short time, the ice was melted 
away upon the distance of 700 to 1,000 miles from the middle 
of the west side of Minnesota to James and Hudson bays, and 
the Lake Agassiz basin was differentially uplifted mostly 300 
to 500 feet, to the height which it has ever since retained with- 
out appreciable later change. To understand the wave-like devel- 


*Geol. and Nat. Hist. Survey of Canada, An. Rep., new series, Vol. 4, for 1888- 
89, pp. 50, 51 E. 


390 THE JOURNAL OF GEOLOGY. 


opment of this uplift, it will be needful to consider it first for the 
southern half and afterward for the northern half of the glacial 
lake area. 

About thirty successive levels of Lake Agassiz have been 
‘recognized by its beaches. A considerable number were due to 
the gradual erosion and lowering of the outlets, and to their 
changes of place and direction, first toward the south and later 
toward the northeast ; but probably more than half of this whole 
series of lake levels are distinctly exhibited only upon the cen- 
tral and northern portions of the lacustrine area, being due 
chiefly to its differential uplift increasing from south to north, ~ 
and in a small degree to the decrease in the gravitative attraction 
of the waning ice-sheet. The five well defined beaches near the 
south end of this ancient lake, named in descending order the 
Herman, Norcross, Tintah, Campbell, and McCauleyville beaches, 
formed at the successive levels of southward outflow as the chan- 
nel was deepened, are each found to be represented, when they 
are followed northward, by two, three, or more, so that near the 
international boundary and in Manitoba, they become subdivided 
into no less than seventeen beaches, marking the stages of the 
subsidence of the lake and in larger proportion of the differen- 
tial elevation of the land. Nearly as many other lower shore 
lines record the stages of the lake while it outflowed northeast- 
ward. My surveys of these shores, with exact mapping and 
leveling, extend more than 300 miles from the south end, to 
lakes Winnipeg and Manitoba and the Riding Mountain. * 

In this southern half of the whole extent of Lake Agassiz, 
the shore of its highest or Herman stage, as represented at the 
north by the uppermost of its divided beaches, has now a north- 
ward ascent of about 35 feet in the first 75 miles north from 
Lake Traverse, which lies in the old channel of southward outlet, 
about 60 feet in the second 75 miles, and about 80 feet in the 


* Geological and Natural History Survey of Minnesota, Eighth An. Rep., for 1879, 
pp. 84-87; Eleventh An. Rep., for 1882, pp. 137-153, with map; Final Report, Vol. 1 
(1884), and Vol. 2 (1888). U.S. Geol. Survey, Bulletin No. 39 (1887), pp. 84, with 
map. Geol. and Nat. Hist. Survey of Canada, An. Rep., new series, Vol. 4, for 
1888-89, Part E, pp. 156, with maps and sections. 


WAVE-LIKE PROGRESS OF AN EPEIROGENIC UPLIFT, 391 


third distance of 74 miles to the international boundary. Its 
whole ascent thus in 224 miles is 175 feet, by a slope which 
increases from slightly less than a half of a foot per mile in its 
southern third to slightly more than one foot per mile in its 
northern third. This beach extends only a short distance far- 
ther north, having been formed when the ice-sheet lay there as 
the northern boundary of the lake; but the second of the Her- 
man beaches, slightly lower and later, reaches as far northward 
as to the limit of my exploration, in the vicinity of Gladstone, 
Manitoba, and Riding Mountain, and in this distance of 308 miles, 
from Lake Traverse to the latitude of Gladstone, it has an ascent 
of 265 feet. In the four successive nearly equal parts of its 
extent from south to north, namely, 75 miles, again 75 miles, 
then 74 miles, and lastly 84 miles, it rises respectively about 35, 
50, 80, and 100 feet; and almost the whole of this change of the 
old beach, from its horizontality at the time of formation, has 
been produced by the gradual uplifting of the lake basin while 
the ice-sheet was retreating from it. i 

The considerably later upper Norcross beach rises in these 
distances about 25, 35, 55, and 70 feet, amounting to 185 feet in 
the entire 308 miles. The upper Campbell beach has ascents of 
about 10, 15, 30, and 35 feet, or 90 feet in all; and the lowest 
of the three McCauleyville beaches, marking the latest stage of 
southward outflow of Lake Agassiz, ascends about 5, 10, 15, and 
20 feet or a total of 50 feet. It is thus seen that far the greater 
part of the uplift of this area had been accomplished before the 
formation of the Campbell and McCauleyville beaches. 

Beyond the limits of my leveling, portions of nearly all the 
shore lines of Lake Agassiz below those of the Herman series 
have been observed and mapped by Mr. J. B. Tyrrell, of the 
Canadian Geological Survey, at localities in northwestern Mani- 
toba and eastern Saskatchewan, bordering the northern half of 
this lacustrine area.’ From a careful comparison of the eleva- 

1 Geol. and Nat. Hist. Survey of Canada, An. Rep., new series, Vol. 3, for 1887- 


88, Part E, pp. 16, with map; Vol. 5, for 1889-90, Part E, pp. 240, with map, sec- 
tions, and illustrations from photographs. 


392 THE JOURNAL OF GEOLOGY. 


tions of the beaches noted by Mr. Tyrrell with those determined 
by my surveys at the south, I am enabled to correlate very sat- 
isfactorily the two sets of shore lines. The northern continua- 
tions of the successive lake levels from the upper Norcross beach 
to the Niverville beaches, which mark the latest stages of the 
glacial lake, just before the recession of the ice-sheet from the 
district crossed by the Nelson river permitted it to be reduced 
to the Lake Winnipeg, are thus identified upon a region lying 
50 to 200 miles beyond the area examined by me. 

Along the base of the escarpments of Riding and Duck 
mountains, where Mr. Tyrrell has traced the beaches and deter- 
mined their heights for a distance of fifty miles between Valley 
and Duck rivers, that is, between latitudes 51° 15’ and 52° N., 
it is found that a very important differential elevation, increasing 
from south to north about three feet per mile, took place after 
the Campbell and McCauleyville beaches were formed, since 
they are thus remarkably changed from their original horizontal- 
ity. It is clearly shown here that the uplifting was not uniformly 
proportionate and regular for the whole area of Lake Agassiz. 
The chief movements of elevation of its southern and central 
part, as far to the north as Gladstone, seem not to have extended 
farther, at least in their full proportion. The district next to the 
north along an extent of 120 miles, to the north end of Duck 
mountain, was perhaps only so far disturbed by these movements 
as was necessitated to connect the rise of the country on the 
latitude of Gladstone with the continuing condition of maximum 
subsidence on the latitude of the lower part of the Saskatchewan 
and the north end of Lake Winnipeg. But there ensued in this 
district, after the date of the Campbell beach, a great differen- 
tial elevation, giving to these late shore lines two or three times 
more northward ascent than that of the Herman beach from 
Lake Traverse to Gladstone; and the total change in level of 
the highest observed beach, probably representing the upper 
Norcross stage, situated at Pine river, on latitude 51° 50’ to 52° 
N., is approximately 400 feet, as compared with this shore line 
at Lake Traverse, about 420 miles distant to the south. Nearly 


WAVE-LIKE PROGRESS OF AN EPEIROGENIC UPLIFT. 393 


the whole uplift of the northern part of the basin was accom- 
plished, however, while the ice-sheet was still a barrier of the 
lake, for the Niverville beach at the Grand Rapids of the Sas- 
katchewan is only slightly higher than on the Red river, 250 
miles to the south. 

The southern and central part of the lake basin, reaching 
north to Gladstone, had been raised nearly to its present height 
during the first third or half of the period of the entire duration 
of Lake Agassiz. Then followed a time, during the second 
third of the lake’s existence, in which the district that includes 
Riding and Duck mountains and extends north to the mouth of 
the Saskatchewan was being rapidly uplifted. But this later 
northward and northeastward advance of the wave of upheaval 
had passed beyond the Saskatchewan before Lake Agassiz was 
lowered to Lake Winnipeg, as is shown by the nearly level Niv- 
erville beaches. The rise of the land approximately to its pres- 
ent height is thus known to have followed close upon the glacial 
recession by which the land was relieved of the ice weight. 

Latest of all, when Lake Winnipeg and the Nelson river had 
come into existence, the shores of Hudson and James bays were 
raised 300 to 500 feet from their late glacial marine submer- 
gence." The remnants of the ice-sheet in that region were not 
melted away until much later than the glacial retreat from the 
northern United States and Manitoba. Moving onward with the 
departure of the ice, the uplifting wave of the earth’s crust has 
raised the basin of Hudson bay 300 to 500 feet since the sea 
was admitted to it, and the upheaval there is not yet completed. 
Though doubtless slower than at first, it is still in progress, 
according to Dr. Bell’s observations, at a probable rate of five to 
seven feet per century. During this last portion of the epeiro- 
genic uplift of our continent from its Champlain depression, the 
whole area of Lake Agassiz, as shown by the still horizontal 


* Dr. RoBERT BELL, Geol. and Nat. Hist. Survey of Canada, Reports of Pro- 
gress, for 1871-72, p. 112; for 1875-76, pp- 340; for 1877-78, pp. 7 and 32 C and 25 
CC; for 1878-79, p. 21 C; for 1882-84, pp- 26-32 DD; Annual Reports, new series, 
Vol 1. for 1885, p. 11 DD; Vol. 2, for 1886, Pp: 27, 34, and 38 G. 


394 LEE, JOURNALVOR GEOLOGY, 


Niverville beaches, lay undisturbed. The loess region of the 
Mississippi valley, having been earliest and permanently uplifted, 
suffered no further change during the progressive elevation of 
the Lake Agassiz basin ; and that in its turn was at rest while 
the great area of Hudson bay has been undergoing elevation. 

Having already shown that the entire duration of Lake Agas- 
siz was about 1,000 years, we must conclude that the uplift of its 
area, probably to heights ranging from 100 feet to mainly about 
500 feet, occurring first at the south and later at the north, took 
place, when in most rapid movement upward, at rates of a halfa 
foot to one foot per year. A century, therefore, would comprise 
an elevation of 50 to 100 feet. The movement, however, was 
evidently more or less intermittent, with pauses of slower uplift 
or stages of rest, when the successive beach ridges were formed. 
- Nowhere else in the records of present or past epeirogenic move- 
ments of any region have so rapid changes of level of large 
tracts been ascertained ; and these changes seem clearly to have 
occurred through a gradual deformation of the earth’s crust by 
quiet flexure, not by faulting and earthquakes, which would 
break the regularity and continuity of the ascents of the beaches 
when traced long distances. The preglacial epeirogenic uplifts 
of drift-bearing areas, also apparently taking place without fault- 
ing, was probably much slower; but their final depression 
beneath the ice-sheet may have been even considerably more 
rapid. Very sudden and great, yet not seismic, uplifts of exten- 
sive areas, as supposed by Prestwich for southern England and 
Wales, to account for the ‘“‘head”’ or “rubble drift,”* and by 
Shaler for the coastal border of New England, to explain the 
origin and preservation of the kames, ” seem, at least in my opin- 
ion, to be physically impossible. 

The probable nature of epeirogenic movements, in their 
dependence on conditions of the earth’s crust and interior, 

t Quart. Jour. Geol. Soc., Vol. 48, 1892, pp. 263-343, with many sections and a 
map. 


2U. S. Geol. Survey, Seventh An. Rep., for 1885-86, pp. 310, 320, 321; Bulletin 
No. 53, 1889, “‘ The Geology of Nantucket,” pp. 44, 45. 


WAVE-LIKE PROGRESS OF AN EPETROGENIC UPLIFT. 395 


remains to be briefly noticed. Between the epochs of mountain- 
building by plication, the diminution of the earth’s mass pro- 
duces epeirogenic distortion of the crust, by the elevation of 
certain large areas and the depression of others; and these 
effects have been greatest just before relief has been given by 
the formation of folded mountain ranges. Two epochs have 
been preéminently distinguished by extensive mountain plication, 
one occurring at the close of the Paleozoic era, and the other 
progressing through the Tertiary and culminating in the Quater- 
nary era, introducing the Ice age. During the last, besides pli- 
cation and overthrust faulting of the Coast range, the St. Elias 
range, the Alps, and the Himalayas, a very extraordinary devel- 
opment of tilted mountain ranges, and outpouring of lavas on an 
almost unprecedented scale, have taken place in the Great Basin 
and the region crossed by the Snake and Columbia rivers. With 
the culminations of both of these great epochs of mountain- 
building, so widely separated by the Mesozoic and Tertiary eras, 
glaciation has been remarkably associated, and indeed the ice 
accumulation appears to have been caused by the epeirogenic 
and orogenic uplifts of continental plateaus and mountain ranges. 
These processes are well consistent with Dana’s doctrine of the 
general permanence of the continents and oceanic basins; for 
upheaval of an ocean bed would not diminish but increase the 
earth’s volume. The late glacial and postglacial uplift of North 
America from its Champlain depression, by the wave-like move- 
ment which has been here described, seems an effort of the earth 
to regain the state of isostasy, or flotation of the crust on the 
heavier mobile interior, which is capable of flow, whether it be 


solid or molten. 
WARREN UPHAM. 


THE OCCURRENCE OF ALGONKIAN ROCKS IN 
VERMONT AND THE EVIDENCE FOR 
THEIR SUB-DIVISION. 


Published with permission of the Chief Geologist, United States 
Geological Survey. 


CONTENTS. 
Geography. 
Topography. — 
Geology. 
Outline of the views previously held regarding the structure and age of the 
Green Mountains. 
The Problem Outlined. 
Reasons fer Refering these Rocks to the Algonkian. 
The Upper or Mendon Series of the Algonkian. 
The Lower or Mount Holly Series of the Algonkian. 
Evidence of Discordance Between Mount Holly and Mendon Series. 
Lithological Differences. 
Structural Differences. 
The Conglomerate-Gneiss Horizon. 
Review. 


GEOGRAPHY. 


Tue area of the Pre-Cambrian rocks forming the subject of 
this paper* is quite limited in comparison with the probable extent 
of these rocks in Vermont. Personal reconnaissance work has 
detected them existing from the town Stratton on the south to 
Rochester on the north, a distance of fifty miles. In only a part 
of this area has detailed work been done, viz.; from Weston to 
Chittenden. On the east the district is bounded by Plymouth 
Valley; on the west by Rutland Valley, an area of about 240 

tThe work, of which this paper forms a partial result, was done under the 
immediate supervision of Mr. Raphael Pumpelly, then in charge of the Archzean 
Division of the United States Geological Survey, to whom my greatest thanks are due 


for useful counsel and advice. It is not to be understood that he is necessarily in per- 
fect accord with me in any views advanced here. 


396 


ALGONKIAN ROCKS [N VERMONT. 397 


square miles. This area has a maximum width on the south of 
ten miles and a minimum width on the north of four miles. The 
delimitation of the Pre-Cambrian as just given is only approxi- 
mate, as in many localities data for its separation from overlying 
rocks are lacking. 

TOPOGRAPHY. 

The Geological Survey has lately issued topographic maps 
of nearly all the territory embraced in the above-outlined area; 
‘in them the pronounced relief of the country is well shown. 
These maps are the Rutland and Wallingford sheets. An 
inspection of the topography reveals a line of high elevations on 
the west, with steep slopes to the east, and steeper slopes com- 
monly on the western side. This line of mountains extends from 
the southern limit of the Wallingford sheet to the northern limit 
of the Rutland sheet, and is only broken by narrow transverse 
valleys where lateral streams come in from the east or southeast 
and join Otter creek in the Rutland valley. On the east side 
of the area a similar range of high mountains extends the same 
distance, but coalesces with the western line in the northern part 
of the Rutland sheet. The convergence of the two lines is geo- 
logically dependent on a narrowing of the series of folds, which 
originally mantled over the central part of the area. North of 
Ludlow mountains an offset to the east occurs which carries the 
line slightly to the east of the Wallingford sheet. 

It will be noticed on the Wallingford sheet that there is a 
central area between the border line of mountains of relatively 
much lower elevations. From Copperas hill in Shrewsbury one 
observes that the mountains appear to encircle him with a line of 
much higher elevations. In a country of strong relief one is 
always impressed with a sense of being in the centre of a series of 
elevations of greater height than those in the immediate vicinity. 
But from Copperas hill the impression is borne out by a glance 
at the topographic maps. On the east and west are the two lines 
of mountains just described; to the south, but farther away, the 
country begins to rise towards the high peaks of Stratton and 
Somerset; to the north, just north of the town of Shrewsbury 


398 THE JOURNAL OF GEOLOGY. 


the high summits of Mendon, Killington and Shrewsbury extend- 
ing east and west shut off the view in this direction. The lowest 
part of this amphitheatre is just northwest of Cuttingsville where 
Mill Creek has cut down to an elevation of 1000 feet above the 
sea. Killington Peak marks the highest point to the north, 4241 
feet. The Central Vermont Railroad finds the lowest pass in the 
southern part of the range through this amphitheatre at Summit 
Station, 1500 feet above the sea. 

Standing on the summit of Killington a wilderness of moun- 
tains meets one’s view; the Taconic Mountains on the west and 
southwest ; the Adirondacks to the northwest; far away north- 
east the White Mountains are plainly visible and the sharp out- 
lying peaks, Monadnock, Kearsarge and Wachusett are seen to 
the southeast. The summits of all these mountains, with the 
-multitude of peaks in Vermont, have the appearance of a remark- 
ably uniform height about which numerous narrow valleys are 
seen; their relatively uniform height can safely be referred to 
an ancient base-level plain, in which upon elevation the north 
and south gently-flowing streams were quickly cut along the 
linear limestone belts, hastening and causing the development of 
the torrential lateral streams that flow east and west from the 
Green Mountain divide. It is to this torrential character of the 
streams and the schistose nature of the rocks that the sharp, 
angular topography in large part seems to be due. Rutland and 
Plymouth valleys, some twelve miles apart on either side of the 
range, are deeply cut in limestone—the former at Rutland to a 
depth of 500 feet above the sea. The great cutting power of the 
streams flowing into this valley from the east is thus seen to be 
due to a fall of over 3000 feet in a distance of six miles. The 
Green Mountain divide is about midway between these two val- 
leys. Relatively less pronounced topographical features charac- 
terize the amphitheatre; sharp, high elevations occur, which 
are capped by more resistant rocks than those making up 
the main central area. It is between the lower rocks of this cen- 
tral depression and the formation along the east and west bor- 
ders and to the north that an unconformity separating the rocks 


ALGONKIAN ROCKS IN VERMONT. 399 


below the Olenellus quartzite into two periods is thought to 


OCCUr. 
GEOLOGY. 


Outline of the views previously held regarding the structure and 
age of the Green Mountains—As far back as 1845, Adams in his 
first Annual Report on the Geology of Vermont? referred to the 
“Primary” system the rocks of the main range of the Green. 
Mountains as far as the state boundary, and eastward. Among 
the rocks mentioned under this head which occur in the area 
studied by me are Green Mountain Gneiss, Mica Slate and Tal- 
cose Slate. In this report these horizons are placed below the 
Stockbridge limestone and the associated quartzite of the Taconic, 
but their relative age is confessedly unknown. In his second 
annual report,? however, he leaves the problem as to whether these 
ane “Ieicomie,” Cem,” Orr Metamorphic,” an open question, 
but still inclines towards a belief in their primary origin. This belief 
is inferred from his statement that the evidence goes to show that 
the limestone and quartzite of Plymouth valley on the east side 
of the range is equivalent to the Stockbridge limestone and quarz- 
ite on the west side, making the core of the Green Mountains the 
older. Adams in no place makes the statement that the belt of 
primary rocks represents the axis of the range, and it is doubted 
if he had any clear conception of the relations of the rocks on 
the east and west sides of the Green Mountain divide. In 1847, 
however, Edward Hitchcock gave two sections in his text book of 
Geology? of the Green Mountain anticline partially and com- 
pletely folded as we see it to-day. The anticline is represented 
as overturned slightly to the west, with a flat crest and a rude fan- 
shaped cross-section; the text* mentions that the strata grow 
newer as one goes westerly, although apparently the series is 
descending. Such a conclusion reached at that time is the 
happy result of a coincidence of schistosity and stratification at 

“Ds OZ: 

*Second Annual Report on the Geology of Vermont. Adams, 1846, p. 168. 
3 Elementary Geology, Edward Hitchcock, 1847, figs. 27 and 28, Dasve 
4Opus. cit., p. 36. 


400 LTTE FOOKINATNOLT NGS OL OGVA 


the localities examined by him ; in a general way the structure is 
that of an overturned series of folds, of an extremely compli- 
cated nature. These sections were made particularly to illustrate 
the structure of Hoosac Mountain, and the structure suggested 
in 1847 finds its verification in 1889’ in Massachusetts, as far as 
the overturning of the anticline to the west is concerned. At 
that time little reference was made to the age of the rocks 
exposed along the axis, but they were mentioned as_ probably 
older than the Lower Silurian, while their relation to the younger 
rocks was not considered. 

Zodack Thompson, in 1856, in considering the ‘Taconic 
System,” makes reference to the structure of the rocks along the 
Green Mountain range’. 

He remarks that ‘‘one of the most marked peculiarities in 

the geology of Vermont is found in the general dip of the strati- 
fied rocks, which is, with a few trifling exceptions, toward a 
synclinal axis extending north and south near the center of the 
Green Mountain range.” He notes a general westerly dip on the 
east side of the range, and an easterly dip on the west side. 
However, the question as to whether the Green Mountain rocks 
are really primary or post-Taconic was with him still in doubt, 
but he states that the weight of the evidence points towards the 
latter view, or more recent age. 

In 1868, T. Sterry Hunt, after a study of the literature, while 
discussing Vermont geology, comes to much the same conclusion 
as Thompson.3 To use his own words: “All the evidence, 
paleontological and stratigraphical, as yet brought forward, 
affords no proof of the existence in Vermont of any strata (a 
small spur of the Laurentian excepted) lower than the Potsdam 

tSee part 3, ‘‘Geology of the Green Mountains in Massachusetts,’ by R. 


Pumpelly, J. E. Wolff, T. Nelson Dale, and Bayard T. Putnam. Monograph U. S. 
Geol. Survey. Submitted in 1889. Not yet issued. 

2 Preliminary Report on the Natural History of the State of Vermont. Augustus 
Young. 1856. Extract from Zodack Thompson’s address on the Natural History 
of Vermont. App. 6, p. 67. 

3On some points in the geology of Vermont, T. Sterry Hunt, Am. Jour. Sci., 
2d series, Vol. XLVI., 1868, p. 229. 


ALGONKIAN ROCKS IN VERMONT. 401 


” 


formation * * * .” The gneiss of the Green Mountains is by 
him and by the geological survey of Canada referred to the 
Quebec group anda synclinal structure is assigned to the range 
probably largely on the basis of the views of Thompson. It is 
thus seen that Adams’ suggestion of the anticlinal nature of the 
mountains and their “‘ primary’ age are passed over, as well as 
the more recent work of the elder Hitchcock, to which reference 
is made below. 

Anything like a close study of the Green Mountains was 
not attempted until 1861, when the two Hitchcocks finished 
their work on the geology of the state. Under the head 
or Awoie IRodks,? Cleimes del, lalitvelicoecls  jolaees tims Wer 
mont rocks occurring east of the Stockbridge limestone as 
far as the Connecticut river, and includes therein the basal 
quartzite of Emmons’ Taconic systern, although the elder 
Hitchcock admits finding therein traces of life in the shape of 
Scolithus and a species of Lingula3 which were not deemed 
sufficient evidence to warrant classifying this horizon with the 
fossiliferous rocks. The younger Hitchcock divided the azoic 
rocks as follows: Gneiss (Adams’ Green Mountain Gneiss) 
hornblende schist, mica-schist, clay-slate, quartz-rock, talcose 
schist, serpentine and steatite and saccharoidal limestone. 
The most western member, the quartz-rock or quartzite with its 
associated conglomerate is mapped as extending the whole 
length of the state. Just north of the area studied by me it is 
represented as thinning out and giving place to ‘‘talcose con- 
glomerate.” 4 On the east side of the mountains a narrow strip 
is colored in extending through the towns of Plymouth and 
Ludlow. Lithological similarity is used as a basis for the cor- 
relation of the conglomerate, which underlies the ‘‘ quartz-rock ”’ 
at Wallingford with the Shawangunk Grit or Oneida Conglomerate 
of New York. The quartzite or quartz-rock is referred for 


Geology of Vermont, 1861, 2 volumes. 

2Opus. cit. Vol. I., pp. 452 to 453. 

3 Opus. cit. Vol. I., p. 500. 

4Opus. cit. See geological map of Vermont. Pl. I., Vol. I. 


PA02 THE JOUKNAL OPSGEOLOGYV: 


paleontological reasons to the Medina, and the hypothesis is 
advanced that by the removal of silicates by circulating waters 
metamorphosis of the quartz-rock to the conglomerate has taken 
place. Reference will be made again to this conglomerate in 
the following pages. Under the head of Gneiss, rocks of great 
variation are grouped. Eight principal varieties dependent on 
accessory minerals such as hornblende and epidote are enumer- 
ated. The gneiss is represented as a slightly curving band, 
extending from the Massachusetts line nearly to the north end 
of the state, gradually narrowing to a point. In the south-eastern 
part of the state another shorter lense is mapped, but this has 
not been explored by the writer. The relations of the gneiss to 
the conglomerate or quartz-rock are not dwelt upon, but many 
phases are assigned to metamorphosed Lower Silurian rocks, 
while the probability that even older rocks may be exposed 
along the anticlinal axis in the range proper, or to the east is 
regarded as a possibility. A deficiency of feldspar is remarked 
upon; because of this peculiarity, according to Hitchcock, 
Adams called it ‘Green Mountain Gneiss to distinguish it from 
rule omeiss:4") WSeven, years later (1863) (Cane aitcheoel 
abandoned his theory as to the age of the quartzite,’ and in a new 
classification refers it to the Potsdam group. The Talcose con- 
glomerate is placed in the “Lauzon” group of the Lower 
Silurian, while to the Eozoic system the Green Mountain gneiss 
is assigned. Inplacing the gneiss in the Eozoic he does not 
infer that it necessarily is older than the Cambrian or Huronian. 
Several reasons are enumerated for referring it to this system, the 
strongest one being the evidence afforded by the occurrence of 
pebbles in the Talcose comglomerate at the base of the Pots- 
dam derived from gneissic rocks. An unconformity beneath the 
Potsdam points to the Eozoic age of the lower rocks.3 

The suggestion made by Adams (above mentioned) that 
the Green Mountains are an anticlinal fold, is followed, in 

‘Opus. cit. Vol. L., p. 454. 

2 The Geology of Vermont, Proc. Amer. Asso., 16th meeting, 1868, p. 120. 


3 Opus. cit. p. 122. 


ALGONKIAN ROCKS IN VERMONT. 403 


1861, by the statement of the elder Hitchcock that such is 
the structure. Numerous sections across the range are given 
in which its anticlinal nature is brought out. Much evi- 
dence is adduced in the text pointing to the same conclu- 
sion based mainly on the occurence of a quartzite and con- 
glomerate on both sides of the range associated with limestones. 
Edward Hitchcock, in 1847, had published sections which 
represented the range as an anticline slightly inverted by 
overturning towards the west. Adams, in 1845, had somewhat 
disconnectedly stated that the ‘granular quartz-rock ” of the 
Taconic had an inverted dip,’ but did not include in the Taconic 
rocks east of the quartz rock. 

In all, the geology of Vermont (1861), contains twelve 
sections east and west across the State. Of these, eleven 
traverse the Green Mountain gneiss; the four southern ones 
show several synclines and anticlines in the gneiss; section 
V, one broad anticline; sections VI, VII, and VIII represent 
the anticline overturned to the west; and in sections IX, X, 
X?, and XI the gneiss is given a simple anticlinal struc- 
ture. On the west side of the range, in all sections except 
the fifth, the quartz rock is given an easterly dip of varying 
angle due to inversion. With one exception, at North Ben- 
nington, where the quartzite dips easterly at an angle of 
5° to 20°, nearly in the position it was laid down, the writer 
has not seen an easterly dip in the rock along this belt as far 
north as Pittsford. The rock is usually quite massive and flinty, 
and bedding is not discernible. An easterly-dipping jointing is 
easily mistaken for stratification. Rocks immediately below 
have a lamination that dips easterly at a high angle, and the 
inversion argued is based largely upon observation on this struc- 
ture ; the coincidence of lamination and bedding along the western 
border has already been spoken of as the probable reason of the 
elder Hitchcock’s accurate decipherment, in 1847, of the real 
altitude of the main axis of the mountains in Massachusetts. 
In 1868 the younger Hitchcock reiterated the interpretation 


« First Annual Report on the Geology of Vermont, 1845, p. 61. 


404 THE JOURNAL OF GEOLOGY. 


of his father, as to its anticlinal structure, and cites as proof the 
supposed equivalence of the ‘‘Potsdam” and ‘Levis” rocks on 
both sides of the range in Wallingford and Plymouth.? 


THE PROBLEM OUTLINED. 


From the opinions held as to the age, character, and structure 
of the Green Mountain axis just given, the main facts that stand 
out most prominently are that the centre of the mountains is 
occupied by strata to which the name gneiss is universally given, 
and that bordering this, on the west, occurs a terrane variously 
called ‘granular quartz,” “quartz rock,” and “quartzite,” by differ- 
ent authors, together with an associated conglomerate. These last 
two rocks have been referred to various horizons from the Azoic 
to the Medina sandstone. Most geologists have grouped the 
central gneiss among the oldest, although Thompson considered 
it more recent than the Stockbridge limestone. 

The relations of the conglomerate to the quartzite are by no 
means so simple as the older geologists were disposed to believe. 
Between the conglomerate and the quartzite there is an extensive 
series of metamorphosed sedimentary rocks which have been over- 
looked in the past, and which are in part the subject of this paper. 
Beneath the conglomerate horizon the gneisses and other rocks 
occurring in the amphitheatres, with their interstratified limestones 
and quartzites make a second series composed wholly cr partly of 
sedimentary rocks separated from the first, of which the con- 
glomerate is the base, by an unconformity sufficiently well iden- 
tified to warrant a sub-division of the Pre-Cambrian Algonkian 
terranes into two series. 


REASONS FOR REFERRING THESE ROCKS TO THE ALGONKIAN. 


It is due to the labor of Mr. Walcott that the age of the 
quartzite on the western border of the range has finally been 
determined definitely. Upon paleontological evidence he refers 
it to the Lower Cambrian horizon and makes it equivalent to the 
red sand rock of Georgia, Vermont; the latter being an off- 
shore, and the former a near-shore deposit. In his Cambrian 


* The Geology of Vermont, Proc. Amer. Assoc. 16th meeting, 1886, p. 121. 


ALGONKIAN ROCKS IN VERMONT. 405 


correlation paper’ Mr. Walcott represents, probably hypothetic- 
ally, the quartzite lying unconformably upon Pre-Cambrian 
(Algonkian) strata. The evidence for a time-break at Clarksburg 
Mountain in Massachusetts is undoubted, but farther north the 
relation of the quartzite to the subjacent rocks is much more 
obscure. As to the age of the subjacent terranes in Rutland 
County, Mr. Walcott refers them to the Archzan.? Since the 
Olenellus fauna, as determined in Vermont, delimits the base of 
the Cambrian horizon, all the sedimentary rocks below (adopting 
the classification of the U.S. Geological Survey ) must be referred 
to the Algonkian. As mentioned above, the quartzite along the 
border is considered a near-shore deposit, and as such, it is evi- 
dence in itself of an approximate subjacent delimitation of the 
Cambrian sediments. On lithological grounds alone it would be 
correlated at once with the Potsdam on the eastern border of the 
Adirondacks, not thirty-five miles west of Wallingford, where 
the base of the Upper Cambrian is plainly seen resting uncon- 
formably upon the lower gneisses. The Potsdam is only faintly 
conglomeratic at the bottom, and the same is true of the quartz- 
ite in Vermont; so that in Vermont, at least, we are apparently 
without a true basal conglomerate in the Cambrian. The Lower 
Cambrian lies directly upon granitoid gneiss twenty-five miles 
south of Wallingford, where the contact is depositional with no 
conglometate whatever. These occurrences indicate that we are 
not obliged to postulate still lower members of the Olenellus 
horizon on the ground that the baseas there shown 1s not delimited 
by a conglomerate. In all the localities in Vermont examined 
by mea reversed dip in the quartzite on the west side of the © 
range has not been observed; in the stratified series just below 
overturns occur along this line. This may be cited as evidence 
of discordance at the base of the Olenellus quartzite, as it is 
extremely unlikely that pronounced overturning could have taken 
place without involving the quartzite in its folds. That a thick 

‘Correlation Papers, Cambrian; Bulletin U. S. Geological Survey, 1890, Pl. II, 
theoretical cross-section at bottom of page. 


2 See Geologic column No. 8, opus. cit. p. 366. 


406 THE JOURNAL OF GEOLOGY. 


bed of massive quartzite might not be affected by minor folds is 
recognized, as it is well known to be among the most resistent 
rocks. The series below, however, possesses quartzites still more 
massive and flinty, rocks which have been involved in close flex- 
ures as sharp as those in fissile associated beds. Through Mas- 
sachusetts and southern Vermont the quartzite is remarkable 
for its persistence. The series immediately beneath is extremely 
variable in character and thickness due to original deposition 
and to the metamorphism that it. has suffered. This series may 
be wanting, as on Clarksburg Mountain and at North Bennington, 
Vermont, where the quartzite lies unconformably upon crystalline 
gneisses. 

In Walcott’s hypothetical section across this continent, the 
Cambrian ocean is represented as sending a long arm up the 
Rutland Valley not covering the Green Mountains or the Adi- 
rondacks. Careful search through the Green Mountains proper 
has not resulted in finding any traces of the quartzite, there is no 
evidence that it once mantled over the range, although it is not 
unlikely that the Plymouth Valley was once occupied by Cam- 
brian waters. There are abundant occurrences, however, of the 
lower series in the heart of the range, where many of the high- 
est peaks are capped by one member or another. There is strati- 
graphical and microscopical evidence that this series has under- 
gone repeated disturbances; the quartzite exhibits but one. 
This fact cannot be used legitimately as evidence of disparity in 
age, as it is probable that the thick bed of quartzite stood 
like a bulwark among more variable, less-resistant strata, not 
taking part in and not recording orographic movements unless 
of extreme intensity. It should not fail to be stated that in 
many localities the quartzite lies directly upon fissile mica schist, 
the upper member of the series below in apparent conformity 
therewith, and the difficulty of referring the schist to the Lower 
Cambrian or the Algonkian is apparent. I am disposed to believe 
it of the latter age and to make it the uppermost member of an 
upper series with the metamorphic conglomerate delimiting the 
series below. There are many reasons for this view, some of 


ALGONKIAN ROCKS IN VERMONT. 407 


which have been given. The limits of this paper will not per- 
mit anything like a full analysis of the evidence, which must be 
reserved for some future time. It seems generally, however, to 
be accepted that sedimentary rocks below the Olenellus horizon 
shall be considered to belong to the Algonkian. But few 
forms of the characteristic fauna of the Lower Cambrian are 
known to extend below this horizon; no fossils have been dis- 
covered in the big Cottonwood section in Utah, where 12,000 feet 
of silicious states and sandstone lie conformably below the olenellus 
zone. It is safe to assume that through such a vertical extent of 
rock the typical Olenellus fauna will not range, and consequently 
part at least must be placed with the Algonkian. That a part of 
the Vermont rocks immediately below the quartzite may be 
proven in the future to belong with the quartzite above is recog- 
nized, but the trend of the evidence collected by me points toward 
its classification in part at least with the Pre-Cambrian sedimentary 
rocks. Without commenting, the reasons for and against this 
view may be concisely stated, as follows: 1. Extreme diversity 
of the metamorphic series, or great lithological difference, as 
compared with the quartzite horizon. 2. Evidence of profound 
orographic movements in the latter not observed in the former, 
the folds often occuring overturned to the west. 3. Occurrence of 
the quartzite reposing discordantly upon granitoid gneiss not far 
south of the area under discussion and also near by in New York. 
4. The near-shore character of the quartzite. 5. The fact that the 
quartzite does not occur in the heart of or to the east of the 
range, whereas the series below has been traced across the 
mountains. 6. In general, the converging of the gneiss-area 
shown on Hitchcock’s map of the State’ indicating a northerly- 
pitching anticline, and in detail shown in small flutings, while 
the quartzite does not exhibit this feature. 8. The occurrence of 
undoubted Algonkian rocks near by, south of Hoosac Mountain 
in Massachusetts identified by Mr. Emerson,’ who finds Lower 


™ Geology of Vermont, 1861. 


2 See Geological Atlas of the United States, Hawley Sheet, 1892, B. K. EMERSON. 
Members of the Algonkian Period are briefly described on Sheet No. 4. 


408 LE YPOURNALVOLGGLOLOGN: 


Cambrian conglomerate gneiss resting unconformably upon the 
upturned edges of a coarse gneiss associated with coarsely- 
crystalline limestone (Emerson’s Hinsdale limestone). A line 
of Algonkian rocks extends southward from Hoosac Mountain 
(including the Stamford gneiss forming the core of the 
mountain) in a belt of oval areas across the Berkshire County 
Plateau. On lithological grounds these rocks would be cor- 
related with some members of the Mount Holly series: of 
Vermont to be described below. They may, however, be 
equivalent to the upper series of the Algonkian which has suf- 
fered less metamorphism to the north. The lack of fossil 
remains in the lower series cannot be used as evidence, since 
metamorphism has probably obliterated all traces of them. A 
disparity between induced structures in the two belts is also of 
‘no value as the quartzite has not recorded the regional cleavage 
owing to its massive character. Rocks stratigraphically above 
it, however, may have had the cleavage developed. The evi- 
dence against this delimitation is furnished by the apparently 
conformable mica schist, which, as a rule, accompanies the 
quartzite, and more locally other members of the series as well, 
which may have contained the Olenellus fauna. It must be left 
for future work to determine beyond dispute the relations of the 
series immediately below the Olenellus zone to the quartzite, 
whether the rocks are conformable or unconformable; if the 
former, whether the delimitation of the Lower Cambrian shall 
be placed above the mica schist or below it. Tentatively, the 
series just below the quartzite, the mica schist at the top and 
the conglomerate at the bottom, will be considered wholly 
or in part of Algonkian age. The separate members of this 
series with estimated thicknesses will now be described. 


THE UPPER OR MENDON SERIES OF THE ALGONKIAN. 


As far as known the best section of these rocks occurs in 
the town of Mendon, one mile north of Mendon village, on the 
west slope of Blue Ridge Mountain (Rutland Sheet). All the 
members identified occur here, although no single section thus 


ALGONKIAN ROCKS IN VERMONT. 409 


far examined has all the members developed characteristically 
or of maximum thickness. Each member thins out and thickens 
along its ‘strike in the most remarkable manner. On Nickwacket 
Mountain, just north of the Rutland Sheet, for example, the peb- 
bly, micaceous quartzite member attains its greatest thickness, 
and the pebbly limestone as well; while in the heart of the range, 
east of the Chittenden flats the lower quartzite - conglomerate 
horizon attains its maximum development. The mica schist is 
best seen along the Mendon section. Provisionally, therefore, 
for descriptive purposes the name Mendon Series will be given 
these rocks. 

That the relations of the different members of this series 
could be worked out seemed for a time a hopeless task, as it was 
subject to such great variations in character, and was so inti- 
mately folded, but the order given below, from less disturbed 
localities is correct within narrow limits. The thickness of the 
different beds is estimated, such estimates being based upon 
great familiarity with them in widely-separated localities, and 
under various habits due to metamorphism. The estimates are 
well within the limits of maximum variation. 

Beginning with the Olenellus quartzite which strikes N. 5 W. 
tO IN, Boy tle WEE TOES, BIS mentioned above, descending 
geologically, is a mica schist. It occurs along the west base of 
the hill, situated in the northwest corner of Mendon. Near the 
quartzite it appears conformable, but as one ascends the hill, 
going east, the rock becomes more crumpled; two hundred 
feet from the quartzite the stratification has been practically 
destroyed, while the regional schistosity, characteristic of the 
Appalachian range in New England, takes its places ins 
induced structure, along the borders of the range strikes quite 
uniformily N. 10° to 15° E., dipping commonly between 60° 
and 80° easterly, although westerly dips are noticed. The 
structure of the schist consists of minute plications and larger 
ones many feet across, closely folded and often overturned to 
west. Minute faulting along the axis of the crenulations has 
produced the schistosity .(ausweisungschiefer) which has been 


410 Iig6h GO OLKINATL, (OG (IROL OE WY, 


mistaken for the dip by the early workers in this region. A line 
drawn tangentially across the apices of the serratures shows the 
dip to be some 45° westerly in the upper (westerly) part. In this 
section the schist may be safely assumed to have a thickness of 
800 feet. In some localities it is not over 50 feet thick, but 
_ just south of Chittenden village more than 1000 feet occur. All 
through the area the schist carries abundant lenses of secondary 
quartz introduced along the bedding and cleavage planes. These 
are considered genetically to be the excess of silica, resulting 
in great part from the decomposition of silicates originally in the 
rock, the alumina and potassium going to form the muscovite. 
Phases of the rock are without such lenses and are nearly free 
from quartz; other phases are largely quartz layers with thin 
folds of mica between. Some phases carry secondary feldspars, 
-but they are exceptional. Under the microscope the normal 
constituents of the schist are seen to be a varying percentage of 
chlorite, a great deal of muscovite in slender, closely-packed 
plates and quartz in thin layers and scattered through the rock. 
Biotite in larger flakes is also universally present, with occasional 
feldspar grains. 

Beneath the schist is the micaceous quartzite horizon, poorly 
represented in this section, but on Nickwacket Mountain having 
a thickness of 500 feet at least, and carrying several thin beds of 
crystalline limestone. Here there are not over 100 feet, with no 
interstratified limestone beds. It has scattered through it 
abundant pebbles of feldspar (microcline and orthoclase) besides 
quartz. The pebbles are small and have undoubted clastic out- 
lines. Owing to their occurrence, this horizon is particularly 
easy to identify. Its strike is a little west of north, and the dip 
80° easterly. Going east from the Olenellus quartzite the dips 
have grown continually steeper and now we find the rocks over- 
turned to the west. This horizon presents many phases traced 
south five miles it becomes a muscovitic schist, highly contorted, 
in which there is no evidence of detrital material ; traced east- 
ward towards the heart of the range, when caught in synclinal 
folds it is a granular, micaceous gneiss. Secondary feldspars 


ALGONKIAN ROCKS IN VERMONT. AII 


have been developed, but the larger clastic feldspar may be still 
detected in a fine-grained ground mass. On White Rock Moun- 
tain its place is occupied by a well-marked sandstone carrying © 
some biotite. Microscopically the rock is made up essentially of 
small grains of clastic quartz. The larger pebbles of quartz and 
feldspar varying much in abundance in different localities. In 
the heart of the range a gneissose phase is produced by granula- 
tion and by development of pale-green, pleochroic muscovite 
and glassy plagioclase from the feldspar pebbles. The mica in 
the most massive phase is also green muscovite. 

Immediately below the quartzite are fifty feet of pebbly, 
crystalline limestone, the pebbles being largely feldspar, like 
those in the quartzite. A narrow valley occurs here in this sec- 
tion due to the relatively rapid removal of the limestone. Nick- 
wacket Mountain along its northern peak exhibits the best 
development of this rock, where its thickness may be safely esti- 
mated at 400 feet. It is only locally pebbly there in contact 
with quartzose layers or the main body of the quartzite above. 
Lack of persistence characterizes this work as one would expect. 
This seems to be due to want of, or to differences in, original 
deposition in many localities; to its alteration to other minerals ; 
to its removal by solution, and to its being squeezed out during 
folding. The rock is locally graphitic and usually quartzose, 
especially where it occurs in thin beds in the micaceous pebble- 
bearing quartzite. Phlogopite is common in little flakes in some 
dolomitic varieties. All through the mountains of the Rutland 
Sheet it forms an easily-recognized horizon. Near the summit 
of Pico peak, just north of Killington, it occurs, and by its rapid 
removal it has given rise to escarpments on the southwest slope 
of the mountain. : 

Some fifty feet of green muscovite schist occurs next below, 
which may be considered a laminated phase of the micaceous 
quartzite which usually appears below the limestone. This 
grades downward into a flinty quartzite along this section. 
Locally the quartzite carries pebbles of quartz and as one goes 
east it is seen to grade into the metamorphic conglomerate that 


412 THE JOURNAL OF GEOLOGY. 


has become so classic through the contributions of the elder 
Hitchcock. This horizon is one of extreme variability and no 
one name can be given it that will have anything like a general 
descriptive application. Further south Mr. Wolff has described 
it as a conglomerate-schist,’ but there the percentage of feld- 
spar, both secondary and original is large and the rock hasa 
marked schistosity. Another phase from the Mendon section is 
a well-developed conglomerate in which the pebbles vary in size 
from a pea up to small boulders. The larger ones are nearly all 
of vitreous quartz, many of a fine blue color. At East Clarendon 
nearly all detrital material is obliterated by the shearing action 
that has developed the perfect lamination observed there. 
Exposed south of Mendon village this horizon is a vitreous mas- 
sive quartzite, probably 500 feet thick, devoid of all evidence of 
stratification. Three miles south of there, the quartzite has dis- 
appeared and a well-laminated muscovitic gneiss, similar to that 
occuring at East Clarendon and Bald Mountain east of Rutland, 
takes its place. One mile north of Chittenden a remarkable phase 
occurs; the rock as a whole is still a vitreous quartzite, but it is 
made up almost entirely of angular and rounded boulder-like areas 
of the same material. The boulders seem to represent in part 
an original conglomerate. If boulders of a composite nature were 
deposited with those of quartz, the silicates have been converted 
into what little ground-mass the rock now possesses. After the 
rock was cemented into a vitreous quartzite, brecciation took 
place, and today we see a mixture of genuine boulders, some 
having a diameter of several feet, and pseudo-boulders of larger 
dimensions, some angular and others having rounded outlines. 
imitating genuine clastics. The former are identified by their 
occasional occurrence in a matrix or cement that has protected 
them from distortion or granulation. East of Chittenden flats 
an even greater development of quartzite occurs where its thick- 


™ Metamorphism of Clastic Feldspar in Conglomerate Schist, Bull. Museum Comp. 
Zool. Whole series Vol. XVI., No. 10, Plate II, shows two excellent microphoto- 
graphs of this phase of the conglomerate where the clastic material is nearly 
obliterated. 


ALGONKIAN ROCKS [IN VERMONT. 413 


ness is not less than 700 feet. Where an excess of shearing 
motion has operated, a well-laminated schist has resulted, 
examples of which may be seen‘at the base of the con- 
glomerate in the Mendon section and extending north and 
south from there; on the summits of Pico, Killington, Men- 
don, Little Killington, and Blue Ridge Mountains, and in count- 
less other localities. ; 

Many phases of this schist occur characterized by acces- 
sories such as chlorite, biotite, and magnetite. An important 
and wide-spread variety carries ottrelite in prisms and radiat- 
ing bundles.* Muscovite predominates over other micaceous 
minerals, both colorless and green varieties occurring, while 
feldspar is only sparingly present. All the varieties of this 
horizon occur in great confusion, grading into one another ver- 
tically and along the strike. In my notes the most schistose 
variety has been called Killington schist, and this with the green 
gneissose phase are the two most common occurrences of the 
rock. It seems preferable to adopt the name conglomerate- 
gneiss for this horizon as it is descriptive of its present mineral 
constitution and suggestive of its past history. All the evidences 
of profound dynamic movement observed in this series are 
observable in the quartzite along the Mendon section. In fact, 
no rock in the Mendon series bears evidence of so great dis- 
turbances. 

Considering 350 feet to represent the thickness of the quartz- 
ite and conglomerate at this point, the total thickness of the 
section is approximately 1,300 feet. It is probable that in some 
localities there may be 2,000 feet of strata, and in the northern 
part of the State no doubt the formation is much more greatly 
developed. Asa whole it is subject to great variations in thick- 
ness, and may decrease to two or three hundred feet, as on the 
south end of Bear Mountains in Wallingford. The relations of 
the conglomerate-gneiss horizon to the underlying rocks will be 


« This phase was described by the writer in the American Journal of Science, Vol. 
XLIV., Oct., 1892.—An Ottrelite-Bearing Phase of a Metamorphic Conglomerate in 
the Green Mountains. 


414 THE JOURNAL OF GEOLOGY. 


considered after a general description of the rocks comprising 
the second or lower division af the Algonkian terranes has been 
given. 


THE LOWER OR MOUNT HOLLY SERIES OF THE ALGONKIAN. 


In the amphitheatre already described, the rocks of this 
series occur well-developed in the towns of Mount Holly and 
Shrewsbury and extend south probably to near the Massachusetts 
line. They are perhaps no more characteristically developed in 
Mount Holly than elsewhere to the south, or possibly to the 
north, but they are best known to me there of anywhere in the 
State. It seems best, therefore, to designate the rocks of this 
central area, or core of the Green Mountains, the Mount Holly 
series. 

In nearly every way the core rocks are contrasted with the 
Mendon series; these differences will be emphasized below when 
the question of the relations of the two series will be discussed. 
A description of the different consecutive members of the series 
cannot be given, as the rocks are too variable in character, and 
dynamic action has involved them in such complications. No 
approach has been made in the determination of the order of 
their occurences, and it is doubtful if such a sequence will be made 
for years to come, unless more discriminating criteria are forth- 
coming. Many unlike members there are, but they are charac- 
terized by no presistence of horizon, or if they are, metamorphism 
has obliterated all distinguishing features. The area appears as 
a multitude of patches of different kinds of rocks, whose rela- 
tions with one another seem impossible of solution. Unlike the 
Mendon series, there is no pronounced northerly lamination 
agreeing in the main with the genuine strike of the stratification. 
The structure here is in part due to zones of unlike mineralogical 
composition; most of the igneous rocks have been well lami- 
nated and the gneisses and schists have their characteristic 
arrangement of constituent minerals. 

A detailed description of all the varieties of rock occurring will 
not be attempted here; some of the more noteworthy areas will be 


ALGONKIAN ROCKS IN VERMONT, 415 


briefly mentioned. Along the south slope of a hill just south of 
Mechanicsville, a section is exposed showing fine-grained biotite 
gneiss at the base, passing imperceptibly into a sugared quartz- 
ite above. This in turn is overlain by coarse saccharoidal lime- 
stone ; anda muscovitic, garnetiferous schist overlies this, capping 
the summit of the hill. These rocks strike in general east and 
west and dip northerly. A section on the southwest slope of 
Ludlow Mountain, two miles southeast of here, exhibits at least 
two beds of coarse limestone grading into tremolite and green 
hornblende, interstratified with layers sol schists ihiese rocks 
strike west of north and dip easterly. On the southwest slope 
of Saltash Mountain a bed of tremolitic limestone interstratified in 
biotitic gneiss trends northwest. At Northam village, a similar 
coarse limestone occurs associated with a vitreous quartzite, a lam- 
inated eruptive rock and a rusty muscovitic schist. All through 
the core there are patches of these coarse limestones in a great 
variety of association, such as with coarse augen-gneisses (a 
common occurrence), quartzites, schists, and other rocks. Fine- 
grained, blue marbles are present in two or three localities. In 
all cases the limestones are in irregular lenses, and are extremely 
local; their occurrence with coarse gneiss affords no evidence of 
structure ; these scattered, irregular outcroppings and differences 
of association make them impossible of correlation. There may 
be two horizons of limestone in the core. or there may be a dozen. 
The same is true of the quartzites and other sedimentary rocks. 
Limestone belts are, however, frequently identified by their meta- 
morphosed equivalent, tremolite, or in rare instances, serpentine 
replaces the limestone. The Mount Holly series has scattered 
all through it these undoubted areas of sedimentary rocks recog- 
nizable where from manifold causes they have escaped destruc- 
tion or metamorphism, and their clastic characters have not been 
obliterated. They probably represent remnants of a once great 
sedimentary series older than the Mendon series. 

The rocks associated with the evident clastics present a 
great variety of texture and mineral composition. Thin sections 
show, however, that the differences are mainly due to variations 


416 THE fOCKNAL ORV GLOLOGY: 


in grouping of the component minerals rather than to differences 
of composition. Gneisses are most common, occurring as fine- 
grained, chloritic rocks or coarse biotite, augen-gneisses. A 
brownish coarse gneiss with porphyritic crystals of orthoclase 
extends in intermittent outcrops from Wilcox Hill on the north 
to Button Hill on the south, a distance of eight miles. This 
rock carries both biotite and muscovite, the latter evidently 
derived from the feldspar. In Eastham, Northam, and east of 
Bear Mountain, there are areas of coarse biotite gneiss with inter- 
stratified beds of quartzite and limestone. Fine-grained, chloritic 
schists and gneisses are abundant, as on the summit of Saltash 
Mountain. 

The area immediately about Mount Holly village on the 
Central Vermont Railroad, is characterized by a great number 
of amphibolites. These occur as schists, either intrusive or 
extrusive, and as dikes, cutting one another, and the country 
rock. They occur interlaminated with various rocks—quartzites, 
gneisses and schists, and possess the local schistosity of the 
enclosing rock. This is as true of the dikes as of the sills, afford- 
ing a conception of how far removed from any key to the real 
stratification is the lamination of these rocks and how faulty 
geological interpretation must be when deciphered on the basis of 
induced structures. Aside from the interest one naturally feels 
in eruptives as old as these, their importance as evidence in 
separating the Mendon from the Mount Holly series cannot be 
overestimated. Modern basic dikes of camptonite and other 
igneous rocks traverse the core rocks, but they are younger than 
the last disturbance of the Green Mountains, cutting Algonkian 
and Cambrian rocks alike. 

Following the accepted definition of the Algonkian rocks, 
this lower series as well as the upper must be grouped as Algon- 
kian. Although possessing many rocks undoubtedly igneous, 
and others whose origin is problematical, there is a considerable 
development of genuine sedimentary rocks, warranting us to 
place the whole series among the Algonkian. The evidence for 
this sub-division, which is based upon manifold differences between 


ALGONKIAN ROCKS. [N VERMONT. 417 


the Mendon and Mount Holly series and their associated phenom- 
ena, will now be considered. 


EVIDENCE OF DISCORDANCE BETWEEN THE MOUNT HOLLY 
AND MENDON SERIES. 


Lithological adifferences—These are many, and furnish im- 
portant data for the classification of the two series into two 
divisions. A hasty description has already been given of the 
upper series and a still more imperfect one of the series below, 
which, owing to its vast variety of rock phase, hardly warrants a 
detailed description of each rock. Ina large way it may be said 
that the upper series is prevailingly schistose; the lower prevail- 
ingly gneissic. The rocks of the upper series can all be referred 
indisputably to a sedimentary origin; part, at least, of the 
lower are of igneous origin, and a still larger part afford no 
criteria which will enable us to assert their origin. Coarsely 
crystalline limestones occurring in the core have in no case been 
detected in the upper rock, and pebbly limestones or quartzites 
are never met within the Mount Holly series. Along the western 
border of the range, from Sunderland to Chittenden, none of 
the core rocks are seen interstratified with the Mendon series. 
An association sometimes occurs, but only when there is evidence 
for a faulted relationship. In the amphitheatre, where the lowest 
rocks occur, none of the upper series have been found. Farther 
north the lower terrane makes up but a small part of the surface 
rocks; the Mendon series capping all the prominent mountains as 
far north as Nickwacket Peak. The chaotic occurrence and lack 
of discoverable sequence in the core rocks find no parallel in the 
relatively persistent and orderly arrangement of the upper series. 
To the eye the core rocks have an older look; they are commonly 
loose-textured when weathered, crumbling often in the hand. 
Under the microscope, the cause for this is readily seen in the 
universal granulation that the rocks have suffered, a phenome- 
non strongly in contrast to the more coherent, less-sugared rocks 
of the border. Other differences in the two series are found in 
their mineralogical composition as a whole. Such differences 


418 TLE OCKINALD OL GHAOLEO GN 


may well be due to unlike environment making deductions in 
favor of unconformity to a certain extent misleading, but the 
contrasts noticed are too strongly marked to admit of dispute 
as to cause. 

The gneisses and schists of the older rocks are characterized 
by a wide-spread development. Colorless muscovite, chlorite, 
orthoclase, biotite, and quartz occur as essential constituents ; 
epidote, zoisite, titanite, and garnets occur as accessories. Of 
these, the first four minerals occur much more sparingly in the 
upper series; the last three are not remembered to occur at all. 
Phases of the lower limestones carry tremolite or serpentine, while 
dark hornblende occurs in abundance. Orthoclase is relatively 
much less abundant in the border rocks where it occurs fre- 
quently as pebbles. Pale-green, pleochroic muscovite, secondary 
plagioclase, magnetite, and ottrelite, so common in the upper 
series, are much less abundant in the lower series; green-mus- 
covite and ottrelite are not known to me in the central area. 
The limestones of the two belts may also differ as to the per- 
centage of carbonate of magnesium present. No investigation of 
this subject has been attempted. 

Reference has already been made to the metamorphosed 
basic igneous rocks, amphibolites, of the central area. One of 
the best sections of these rocks is displayed in the railroad-cut 
at Summit station, where they are exposed for nearly half a mile. 
Numerous separate members can still be distinguished in the 
mass by textural variations. They are cut by dikes of the same 
material and also by more modern dikes of camptonite. Such 
a series of amphibolites probably represents a period of volcanic 
activity, antedating the Cambrian, of great areal extent. Nearly 
everywhere, where these lower rocks are exposed, amphibolites 
are present also. To the north they occur only in scattered 
patches associated with granitoid gneiss; to the south reconnais- 
sance work has not detected them, but they probably occur 
there. Mr. Wolff has described an amphibolite from a hill situ- 
ated about one mile south of Mount Holly station, and he refers 


ALGONKIAN ROCKS IN VERMONT. 419 


it with probability to an original diabase.t. Remains of an orig- 
inal bisilicate (augite) can still be found in the rocks. Whether 
diabase or basalt their Occurrence in sheets traversed by dikes 
of the same material and their great abundance lead me to con- 
sider them surface flows or intrusives. Their abundance may be 
cited as evidence of extrusive origin since it is extremely unlikely » 
that any area, reasoning from analogy, would be traversed by so 
large a number of intrusives. This view is also sustained by the 
fact that diabases and basalts are prevailing surface flows. Such 
regions as the Triassic (Newark ) of the eastern United States, Kew- 
eenaw Point, the western plateau, and the Deccan being examples. 
Their restriction to the Mount Holly series not only points to 
their extrusive origin, but whatever their origin they afford 
almost positive evidence of an unconformity at the top of the 
series; if intrusive, we should naturally expect to find them 
occurring in the Mendon series, which is not the case; if extru- 
sive, their occurrence only in the core rocks iseven more in favor of 
the proposed subdivision. As to the importance of the evidence 
afforded by these rocks no better confirmation can be found than 
the following from Van Hisez “« Eruptive rocks are often an 
important guide in determining structural discordances. These 
are valuable when the older series has passed through an epoch 
of eruptive activity before the newer series was deposited. In 
such cases, bosses, contemporaneous or intrusive beds, volcanic 
fragmental material or dikes may occur in the older series which 
nowhere are associated with the newer. It is possible, of course, 
that eruptives may penetrate the inferior members of a series and 
never reach the higher formations ; but if it is found that the 
supposed inferior series is associated with abundant material of 
igneous origin which never passes beyond a certain line, it is 
almost demonstrative evidence of the later age of the newer 
series.” 


™ Geology of the Green Mountains in Massachusetts, by R. Pumpelly, J. E. Wolff, 
T. Nelson Dale, and Bayard T. Putnam, Monograph U. S. Geol. Survey, Part 3, sub- 
mitted in 1889. 

‘Correlation Papers—Archzean and Algonkian, Bull. No: 86, U.S. Geol. Survey, 
p. 520. 


420 IVE J (ONQIIMAUL, (OF (GIRO OGG. 


Structural differences. — Evidence afforded by a study of 
the structure in the two series, both original and induced, 
has an important bearing upon the separation of the two 
terranes. Of first importance may be mentioned the relatively 
orderly strike of the lamination and bedding of the upper 
series in comparison with the strike and disordered succes- 


Fic. 1. Initial development of strain-slip cleavage, dipping to the right in a 
schistose phase of the conglomerate-gneiss horizon. The fluted bedding planes are 
seen dipping to the left. Under the microscope the faulting of the sharp crenulations 
is plainly visible with secondary formation of muscovite along slipping planes. 


sion of the core rocks. The Mendon series in many local- 
ities is flexed into minute puckerings and minor folds hav- 
ing northerly pitching axes overturned to the west. Along 
the western line of the folds, and in synclinal troughs, sharp 
crenulations are developed; on the backs of folds stretching and 
consequent schistosity are best shown. When the sides of the 
crenulations are forced to move over each other strain-slip clear- 


ALGONKIAN ROCKS IN VERMONT. 421 


age is produced. A beautiful example of this is seen in 
Fig. 1, from the schist phase of the conglomerate gneiss two 
miles north-east of East Clarendon, near its contact with a coarse 
underlying gneiss. Blue Ridge and Pico Mountains are now 
capped by schist produced upon the back of folds. Close fold- 
ing with axes striking nearly north and south only occurs in the 
amphitheatre near the summit of the greatest elevations, as on 
Mount Holly—a hill about a mile south of the station by that 
name—and near the contact with the Mendonseries. The rocks 
of the core have no presistent strike and dip, neither of schistosity 
nor bedding ; east and west strikes are as numerous as those trend- 
ing north and south and the dips are as variable. Throughout the 
core the gnarled and tortuous folding of the strata represents the 
effect produced by the operation of repeated periods of mountain- 


building action of enormous force, directed not always from the 
east and west as in the Mendon series, but from the north and 
south as well. 

A careful study of the Mendon series recognizes but two 
periods of orographic disturbance, the second acting along 
approximately the same lines as the first. This is well-indicated 
under the microscope, and in the field it is beautifully shown at 
North Sherburne where the strike of the rock (a conglomerate ) 
is N. 25° W.—a trend produced by the first period of folding. 
The schistosity of the Green Mountains traverses this obliquely, 
making an angle of 35°—qo°, striking N. 10° to 15° E. Both 
structures dip easterly at a variable angle. Forces that induced 
the regional lamination of the range could not have produced 
the great variety of trend observed in the folding of the Mount 
Holly series. The question of difference of environment of the 
central or lower parts of anticlines as compared with the outer 
must not be overlooked. All the phenomena go to show that 
the superior or Mendon series was above the neutral zone and 
that great slipping, stretching and crumpling took place therein 
dependent upon position in this belt. Below the neutral zone 
during the folding of the Mendon series undoubtedly most of 
the core rocks were placed where crushing would largely 


422 THE JOURNAL OF GEOLOGY. 


exceed shearing and the development of the regional schistosity 
would not be expected. It is nevertheless true that the core 
rocks, although as a whole more massive than the border series, 
have in most localities a pronounced lamination not always due 
to the formation of micas, as inthe Mendon series, but frequently 
the result of a rearrangement of the chemical combinations of 
the rock brought about by metasomatic and dynamic agencies. 
This is shown by the formation of amphibolites from some 
basic eruptive rock and by banding produced by the parallel 
injection of pegmatitic veins along the schistosity. If the core 
rocks were below the neutral zone during the folding that induced 
the regional clearage in the border series, then manifestly the 
intricate flexing of the inferior rocks was developed before the 
deposition of the Mendon series; if the core rocks were above 
‘the neutral belt they should have the normal lamination and 
characteristic folding universally occurring in the upper series, 
which is not the case. 

A coarse granitoid gneiss and some associated quartzose sedi- 
mentaries occurring at North Sherburne are characterized by 
hundreds of minute faults to the square foot, having most diver- 
gent trends. That this was an area below the zone of neutral 
motion, thus permitting compensation by faulting or crushing is 
not tenable since the rocks are not more than 300 feet below a 
metamorphosed conglomerate, in which no faulting of this nature 
has taken place. In this phenomena we have more evidence 
pointing to the conclusion that the core rocks have under- 
gone many mutations not participated in by the overlying 
Mendon series and must therefore be separated by an uncon 
formity. 

The conglomerate-gneiss horizon.— On the west side of the 
range, the Hitchcocks have colored in this horizon extend- 
ing in scattered patches beneath the “quartz-rock” trom 
Sunderland on the south to the Canadian boundary, thicken- 
ing toward the north. A patch is shown at Sunderland and 
another at Wallingford. Beginning in the town of Ripton, 
if this interpretation be correct, it extends continuously across 


ALGONKIAN ROCKS [IN VERMONT. 423 


the State. Between the areas indicated upon their map,’ the 
writer has observed it or its metamorphosed equivalent, so it is 
known to extend in an unbroken line from near North Benning- 
ton the entire length of the State as a persistent characteristic 
horizon. At the Massachusetts line it is wanting where the 
Olenellus quartzite reposes discordantly upon a granitoid gneiss. 
On the east side of the range it is described by the above- 
mentioned authors as occurring in a narrow band running across 
the towns of Plymouth and Ludlow, and is correlated with the 
conglomerate horizon of the Rutland Valley. It is largely upon 
this eastern occurrence of the conglomerate that the anticlinal 
nature of the Green Mountains was hypothecated by them. The 
phenomena of stretching of quartz and gniess pebbles in this 
horizon and their destruction thereby, furnished the elder Hitch- 
cock with the necessary confirmatory data for his then revolu- 
tionary ideas concerning the production of gneisses from con- 
ylomerates by metamorphism. About one mile north of 
Tyson’s Furnace in Plymouth and on the south slope of Bear 
Mountain in Wallingford occur the now classical localities where 
the conglomerate was most carefully studied by him and where 
nearly all his illustrations were obtained. It is doubtful if two 
areas can be found in metamorphic regions where the change of 
sedimentary rocks to crystalline gneiss is better or more satis- 
factorily shown. It was with fear and hesitancy that the ques- 
tion of this new effect of metamorphism was discussed, but the 
carefully-elaborated arguments advanced show that a keen appre- 
ciation of the proper interpretation of the phenomena revealed 
there was felt by the author of this most valuable contribution 
to the science of geology. 

The first area described (the Wallingford locality >) is situ- 
ated about where the 1500 feet contour makes a sudden jog to 
the south. Here the elongation and flattening of the pebbles, 
their contorted character and the transition of the rock to gneiss 
are remarked upon. 

tOpus. cit. Pl. I., Vol. II. 

2 Opus. cit., Vol. I., pp. 32 to 44. 


424 THE JOURNAL OF GEOLOGY. 


In Rhode Island the Newport conglomerate with its indented 
and elongated pebbles was a starting point in the series of changes 
from an unchanged conglomerate to a gneiss, the Wallingford con- 
glomerate being an intermediate stage of metamorphism, while 
the Plymouth occurrence represented the completed alteration. 


Fic. 2. Longitudinal cross-section of stretched conglomerate-gneiss. The 
pebbles in the upper half of the figure are mainly gneiss. In the longest pebble near 
the center the original lamination can still be made out. The more feldspathic clastics 
are now seen as thin linear films of crushed quartz and feldspar between more 
resistant pebbles of quartz and quartzose gneiss. From Edward Hitchcock’s Green 
Mountain locality, one mile north of Tyson’s Furnace, Plymouth, Vt. Size of block 
photographed 13 x 8 inches. 


Much more interest was felt in this last-discovered locality where 
gneissic and quartz pebbles are flattened and pulled out into 
alternating, 
sugared condition, but still clearly possessing their deformed 


clastic outlines. Although not directly pertinent to the subject 


non-persistent bands of these minerals ina highly 


of this paper, it seems desirable to reproduce here a photograph 
of a block of this conglomerate, cut in longitudinal cross-sec- 


ALGONKIAN ROCKS IN VERMONT. 425 


tions, now in the geological exhibit of the Agassiz Museum, 
Cambridge, Massachusetts, Fig. 2. A fair percentage of the 
pebbles are of a composite nature (gneiss) and as would 
be expected, they have yielded most easily to the deforming 
forces. They now form in large part with secondarily-developed 
green muscovite, feldspars and cement of the pebbles, the more 
schistose folia of the rock. Stretching and flattening have resulted 
from a force operating along the plane of bedding in the direc- 
tion of dip. The pebbles have been elongated most in an east 
and west direction, and their perceptible flattening indicates that 
this elongation took place under enormous load ; an environment 
unlike that of the pebbles at South Chittenden, which have 
undergone elongation without marked lateral yielding. The 
environment factors here were probably extreme load, a force 
tending to push the rock as a whole towards the west, and the 
presence of water charged with inorganic compounds that pro- 
moted the alteration of the clastic feldspar material, already 
weakened by sub-aérial decay to more stable compounds under 
the changed environment, and at the same time cementing the 
mosaic of quartz and feldspar grains resulting from the enforced 
granulation into a coherent rock. It seems unnecessary to pos- 
tulate a high degree of temperature to account for these phe- 
nomena; nor has plasticity, as properly defined, played any 
part in the deformation of the quartz and gneissic pebbles. 

At North Sherburne a conglomerate occurs of considerable 
thickness and extends south to Ludlow, a distance of twenty-five 
miles. It is fully as persistent on the east side of the range in 
the area under discussion, as on the western, and, although some 
phases are unlike the western belt as a whole, it may be safely 
correlated with the conglomerate-gneiss horizon making, as first 
suggested by Adams, an anticlinal axis between Plymouth and 
Rutland valleys. 

The question of the relations of the conglomerate-gneiss to 
the lower or Mount Holly rocks, has been most carefully studied 
onthe western side of the range where the country is more open. 
At East Clarendon; just north of South Chittenden, and at Hitch- 


426 THE JOURNAL OF GEOLOGY. 


cock’s Bear-Mountain locality, are three of the most instructive 
sections, where the contact relations of the two series are shown. 
All these sections show the relations of the two series in apparent 
structural conformity brought about by dynamic movements 
exercised throughout the rocks as a whole, but having a maxi- 
mum obliterative effect immediately at the base of the conglom- 
erate, since at this point the underlying rocks were best condi- 
tioned to record such action. Speaking of the transitional beds 
on Hoosac Mountain, between the Lower Cambrian quartzite- 
conglomerate horizon and the granitoid gneiss, Mr. Pumpelly 
writes as follows:? ‘This unabraded zone of crystalline rock,” 
(reference is made here to the zone of semi-disintegrated rock on 
which the conglomerate was deposited unconformably) ‘‘ which 
had its rigidity weakened by beginning disintegration, would, 
~under folding, pressure, and metamorphism, show on the one 
hand a perfect and true transition into the parent crystalline rock, 
and on the other hand pass into the much younger beds through 
the similarity of the constituents derived from it; and an appar- 
ent conformity would be forced upon the whole series, and the 
time break would be masked by the foliation induced by the 
shearing action due to a slipping movement.’”’ An interpretation 
which so satisfactorily accounted for the transition obtaining on 
Hoosac Mountain can be as well applied to the transitions in 
Vermont at the base of the conglomerate, only here the terranes 
below are of a very variable character, and in a great part were al- 
ready possessed of a gneissic habit which by-rearrangement would 
even more readily take on the lamination of the rocks above. 
Wherever the conglomerate gneiss is found on the west side of 
the range a perfect transition to the lower rocks always exists, 
and all evidence of a discordance, such as obtains in more 
modern rocks of necessity must have been obliterated. It is 
thus seen that criteria applicable for the detection of more recent 
time-breaks have but little value where the rocks have been 
subjected to such powerful and repeated orographic disturbances, 


* The Relation of Secular Rock-Disintegration to Certain Transitional Crystalline 
Schists, R. Pumpelly, Bull. Geol. Soc. of America, Vol. II., p. 215. : 


ALGONKIAN ROCKS IN VERMONT. 427 


unless the conglomerate itself be taken as sufficient proof of an 
unconformity. 

A practical difficulty was first met in finding a source for the 
abundant pebbles of blue quartz which occur so plentifully in the 
rock, and although sources for them are known, the proportion 
of such material seems to bear no proper relation to the known 
extent of rocks in the Mount Holly series that would be likely 
to yield pebbles of this mineral. Reference has already been 
made to a coarse phase of the conglomerate near South Chitten- 
don where its clastic quartz best deserves the name of boulders. 
Such coarse phases are exceptional. An unusually coarse variety 
occurs one mile north of Mendon village. With the quartz peb- 
bles there is a plentiful sprinkling of gneiss pebbles, varying in 
size from small grains up to two feet in diameter. Clastic areas 
of orthoclase are also numerous; pebbles two inches in diameter 
being the largest. Under the microscope abundant small grains 
of detrital feldspar can be detected. At this locality the 
original character of the rocks seems best preserved of anywhere 
that it is known to me, and a careful comparison of its gneissic 
clastics with the gneisses of the lower series immediately subjacent 
was made in hopes of being able to refer the pebbles to their 
sources. Macroscopically there appears to be no doubt that most 
of the pebbles were derived from the complex of gneisses to the 
east, and in the days before microscopical methods were used such © 
a source would have been unhesitatingly affirmed. But today the 
microscope instead of simplifying one’s difficulties apparently only 
adds to them. It is seen that the conglomerate here has recorded 
the evidence of dynamic action to a somewhat less extent than 
in many localities, but still an evident effect of metamorphism is 
observed. The micro-study of the lower gneiss shows them to be 
coarse to fine, irregularly-laminated orthoclase rocks in which both 
quartz and feldspar are badly crushed and distorted. About the 
resulting mosaics have been developed abundant epidote and 
titanite crystals and patches of biotite, colorless muscovite and 
chlorite. In the clastic gneiss little or no epidote or titanite can 
be detected, while there is always present more or less pale-green 


428 THE JOURNAL OF GEOLOGY. 


pleochroic muscovite, that characterizes the conglomerate-gneiss 
horizon and give to it its greenish color, the result of alteration of a 
potassium feldspar during dynamic movement. Its other con- 
stituents seem to be identical with the neighboring gneisses, but 
on so slim a basis it is not deemed safe to refer the clastics to 
any particular gneiss area in the Mount Holly series. The feld- 
spar clastics appear to have been derived from the pegmatite 
veins that are very abundant in the lower rocks to the east. 

The Bear Mountain locality in some respects is more import- 
ant in its bearing on the question of non-conformity than the one 
above described; no one area furnishes the data for all the con- 
clusions to be drawn from the horizon. Attention was first called 
to the abundance of small clastic pebbles of feldspar oceurring 
there, by Edward Hitchcock in Nool.. and) im Tsoi = bya vie 
Wolff.2. As remarked by Mr. Pumpelly,? there seems to be ‘“‘no 
other source than the débris of the deeply decayed Mantle” on 
which the conglomerate was lain down, and as such they point 
to a land surface close at hand where sub-aéreal decay had weak- 
ened the cohesion of the rocks, permitting a positive movement 
of the sea to build the more superficial mantle containing the 
feldspar grains, and a lower semi-disintegrated zone of gneiss and 
loosened blocks of gneiss into’a conglomerate. The phenome- 
non of false bedding is well shown here, and was figured by 
Hitchcock‘; transitions from coarse sediments, when the pebbles 
of quartz attain a diameter of nearly a foot, to fine material, 
point to the ordinary conditions obtaining along our coast. So, 
too, the outlines of the clastics are those that are characterist- 
ically produced by wave action, unless deformation has taken 
place, which is usually the case at this locality. All these facts 
are subordinate in their value compared to the conclusion to be 
drawn from the conglomerate-gneiss horizon as a whole, extend- 
ing as it does across the State of Vermont, and presenting in one 

‘Opus. cit. p. 34. 

2Metamorphism of Clastic Feldspar in Conglomerate Schist. Bull. Comp. 
Zool., Vol. XVI., pp. 173 to 183. 

3Opus. cit., p. 211. 

4 Opus. cit., p. 32. 


ALGONKIAN ROCKS IN VERMONT. 429 


place or another all the eminent characteristics of a basal con- 
glomerate. 

An apology may be in order for dwelling so long upon the 
evidence detailed in support of the conclusion that an uncon- 
formity occurs at the base of the conglomerate, when, to many, 
the evidence afforded by the conglomerate alone would he con- 
sidered amply sufficient ; but in an area so greatly disturbed and 
metamorphosed as this, it seems best to enumerate all possible 
criteria that can be legitimately advanced tending to sustain the 
above conclusion. 

SUMMARY. 

To summarize briefly, this paper is hoped to have substan- 
tiated essentially the following facts: 

1. That immediately beneath the Lower Cambrian quartzite 
in Vermont there is a series of more or less metamorphosed 
clastic rocks of no inconsiderable thickness; the upper member 
of this series being a dark chloritic mica schist ; the lower mem- 
ber a highly metamorphosed conglomerate, and between these 
several pebbly limestones and pebbly micaceous quartzite strata. 
Evidence for and against an unconformity at the top of the 
schist is presented, but no satisfactory data are advanced to sus- 
tain either interpretation. The evidence for a time-break at the 
base of the conglomerate is thought to have been established, 
and the data in support of this conclusion are discussed in some 
detail. These rocks are referred to the Algonkian Period and 
are provisionally called the Mendon series. 

2. That below the Mendon sedimentary rocks, a still older, 
more metamorphosed and more variable series of stratified rocks 
of Algonkian age occurs, together with gneisses and schists, 
whose origin is unknown, and abundant metamorphic equivalents 
of old basic igneous rocks. Many of the varieties of rocks 
7 occurring in this series are enumerated, and, together with their 
structure are contrasted with the rocks of the Mendon series, 
whose basal member, the conglomerate, delimits the series above. 
From their typical development in the town of Mount Holly, 
Vt., it is suggested that these rocks be called the Mount Holly 
Series. CHARLES Livy WHITTLE. 


JE IDI TORI AIOS. 


THE protracted ill health of Major J. W. Powell has led 
to his resignation of the office of Director of the United 
States Geological Survey, and to appointment, with his hearty 
endorsement, of Professor Charles D. Walcott who has had 
charge of much of the executive work of the Survey for the past 
year or more. Although Major Powell has suffered much from 
other forms of ill health for several years, the immediate cause 
of his resignation, we understand, was a renewal of trouble from 
his amputated arm, which had reached a stage requiring re-am- 
putation. As is well known, Major Powell lost his right arm on 
the evening of the first day of battle at Shiloh, while he was gal- 
lantly trying to hold his battery’s position till night should come 
to the relief of the sorely pressed army. We are glad to learn 
that the re-amputation has already been successfully performed, 
and that there is every prospect of a speedy recovery. The 
probability of a measurable restoration to health has been 
regarded sufficient to warrant Major Powell in retaining the less 
exacting directorship of the Bureau of Ethnology, and to give 
encouragement that he may be able to finish the important eth- 
nological studies upon which he has been engaged for several 
years. It is earnestly to be hoped that this may be realized, 
and that he may be permitted to add to his record as an execu- 
tive the more distinctively scientific fruits of a very original and 
philosophical mind. 

The appointment of Mr. Walcott meets with the hearty 
concurrence of his associates, and will be approved, we are sure, 
by scientific men generally. Though a comparatively young 
man, he has shown both investigative and executive ability of 
an unusual order and possesses in high degree the personal qual- 
ities which the position requires. 

430 


EDITORIALS. 431 


Major Powell’s administration has been a very notable one, 
and will doubtless stand forth even more distinctively as we 
recede from it in time and see it in perspective when its greater 
outlines will be better defined and its details will fall into their 
places as parts of the whole. From a comparatively small corps 
of workers, with an inadequate appropriation, trammeled by leg- 
islative restrictions and uncertainties, and embarrassed by unto- 
ward inheritances from three inharmonious territorial surveys, 
the organization has grown to be perhaps the largest and most 
productive of official geological surveys. Its very strength has 
indeed been an occasion of criticism on the part of some who 
have conceived themselves to be unfavorably affected by its 
great influence. 

One of the most notable characteristics of the administration 
has been the large consideration given to the differentiation of 
investigative work. Toa degree perhaps never before equaled 
in governmental work facilities have been afforded for the care- 
ful and broad investigation of special subjects of a fundamental 
nature. A portion of the results of these studies have appeared 
in the special papers of the annual reports, in the monographs, 
and in the correlation papers, but a considerable portion are yet 
to be issued. 

Externally, perhaps the most conspicuous feature of Major 
Powell’s administration has been the great prominence given to 
topographic work. If this work be conceived as subserving no 
other function than that to which topographic maps were usually 
put previous to the current decade, it might well be doubted 
whether so large a proportion of the resources at the command 
of the Survey were wisely given to this part of the work, and 
the question of ratio and proportion may be a pertinent one in 
any case, but it is necessary to a proper interpretation of the 
policy of the Survey to note that an important evolution of geo- 
logical science has been in progress, and that topographic and 
physiographic factors now play a part in good geological work 
that they have never played before. Physiographic geology has 
had a new birth, and has taken an important place among the 


432 THE JOURNAL OF GEOLOGY. 


essential branches of the science. Major Powell has himself, as 
an individual investigator, been one of the pioneers in this new 
departure, and the doctrine of the base-level, which we owe so 
largely to him, taken with its corollaries, constitutes one of the 
most important contributions of recent decades. In so far as 
the topographic work of the Survey has become an adjunct and 
antecedent of the new physiographic phases of geology, it mer- 
its the highest commendation. In so far as it has fallen short of 
this, it perhaps expresses the practical difficulty of at once ren- 
dering topographical work geological, a difficulty not to be won- 
dered at since topographical work has been so largely regarded 
as a function of some other science than geology, some science 
in which the mere hypsometrical factors of relief, mechanically 
represented, have been chiefly considered instead of the genetic 
factors that give meaning to the topography. Until a genera- 
tion of geological topographers can be trained up, topographic 
work cannot be expected to be other than mechanical and rela- 
tively expressionless. It may be questioned whether some of 
the topographic effort that has taken the eatenstonal form might 
not better have taken an zzfenszeve form in the interest of trans- 
muting mechanical topography into geological topography, or, 
in other words, the substitution of genetic expression for mean- 
ingless mechanicalism. But, withal, the great development of 
the topographical side of the Survey has been in the line of 
progress and the needed transformation in the fundamental 
nature of the work should grow out of it through persistence in 
the educative process already begun. We have no sympathy 
with the geologist who looks upon topographic work as an 
alien function to be performed by those whose profession does 
not lead them to know how topographic relief was produced or 
what it means, and who carps at the Survey for an alleged inva- 
sion of fields outside its domain. 

Under Major Powell’s administration, the physical and philo- 
sophical phases of the Survey have received a more marked im- 
petus than the palzontological, though an able and active corps 
of paleontologists have always formed a large division of the 


EDITORIALS. 433 


staff, and have made most important contributions. This ratio 
of development has been, perhaps, duly proportionate to the 
demands of the growing science, for the paleontological side of 
the governmental work was previously, we think, the more 
advanced and occupied a relatively larger part, and might well 
advance less rapidly and permit the physical wing to come 
abreast of it. 

The administration has had a good degree of success in the 
very delicate and difficult task of codrdinating the work of the 
general government with that of the states and in securing 
friendly and helpful codperation. Very notably excellent results 
are being worked out by the joint effort in some cases. 

Not to unduly lengthen this notice by dwelling upon other 
salient features of Major Powell’s administration, suffice it to say 
that it has been marked by originality and boldness of concep- 
tion, by good judgment in organization, by unusual skill in 
securing favorable legislative action, by large liberty to col- 
leagues in the prosecution of their work and the publication of 
their results, by broad and comprehensive views of the functions 
of the Survey, and by great courage and tenacity of purpose in 
the endeavor to compass them. 

The administration goes into the hands of a chosen colleague 
in whom the retiring Director will find a worthy successor. We 
predict for Mr. Walcott a brilliant administration. ne Cs 


% OK 
* 


WE very much regret that the difficulties connected with the 
Missouri Geological Survey, to which we have once before made 
allusion, culminated recently in the abrupt termination of Mr. 
Winslow’s directorship. This unfortunate result finds some miti- 
gation, however, in the fact that the Survey is not altogether to 
be abandoned, as seemed at one time not unlikely, and that it 
has been placed in so excellent hands as those of Dye KG. IRE 
Keyes, of the Iowa Geological Survey. It is also gratifying to 
learn that Mr. Winslow has been engaged to complete his report 
on the lead and zinc deposits, and that thus a very important 


434 DT fi. OWCLINALE OLN GTS CHL OGN 


part of the Survey’s work will be saved from loss, though the 
report will doubtless not be brought to the degree of complete- 
ness it would have reached under better conditions. 

Dr. Keyes will be embarrassed at the outset by severe finan- 
cial limitations, but we trust that his abilities and tact will win a 
large success in the end. 


fey (Ce 


IR IBV IIE MWES. 


The Lafayette Formation. By W. J. McGee. Twelfth Annual 
Report of the U. S. Geological Survey, pp. 347-521, 5 maps, 
5 plates, 45 text cuts. 


Tuts brochure almost opens a new chapter in geological history ; 
for although the formation is essentially a surface feature over an area 
of 100,000 square miles, and only thinly-covered by a mantle of 
Columbia sands extending over another 150,000 miles, yet the 
knowledge of these deposits was fragmentary, and they were not 
correlated as a unit—or interpreted in their bearing on the phys- 
ical history of the continent, until the appearance of this work.‘ The 
investigation of the formation was commenced in Mississippi by Pro- 
fessor E. W. Hilgard, who gave it the above name, though the later 
appellation of “Orange Sand,” given by Professor J. M. Safford, in 
Tennessee, was commonly accepted. Subsequently, McGee’s researches 
along the Atlantic border made known the Appomattox formation, 
which the author afterwards found to be a northern continuation of 
Hilgard’s Lafayette, or the “‘Orange Sand.” Confusion also arose in 
the application of the latter name, and by consent of all the authors, 
Hilgard’s original name was adopted. 

The report is written in a narrative form in only a few chapters, which 
are unfortunately not sufficiently subdivided under topical headings to 
make the arrangement most favorable as a work of reference. On the 
other hand, the set of maps is particularly clear and explanatory of the 
text. ; 

“The Lafayette formation may briefly be described as an extensive 
sheet of loams, clays, and sands of prevailing orange hues, generally mas- 
sive above, generally stratified below, with local accumulations of gravel 
along the water-ways’, (p. 489). The physical structure is peculiar, 
although the deposit resembles certain residuary clays derived from the 
Archean, and from lower Paleozoic limestones, from which it is not 
always easily distinguished when the gravels are absent, while the gravels 

*The author had published several advance notices prior to the appearance of the 


present report. 
435 


436 THE JOURNAL OF GEOLOGY. 


may resemble those of the sometimes-underlying Potomac, or Tuscaloosa 
series. Again, the physical features of the whole formation are often 
reproduced in the overlying Columbia formation. Although the 
Lafayette is remarkably persistent in its characters, over the enormous 
area, yet care must be exercised in its study. In exposed sections, the 
surfaces become case-hardened, and stand as vertical walls, on which 
often the shades of ferruginous oxidation can be seen. ‘The subjacent 
formations give rise to local variations in the amount of sand, clay, or 
calcareous matter, which is particularly shown in the agricultural feat- 
ures. This formation once covered the entire coastal plain of both 
the Atlantic and Gulf margins from Maryland to Mexico, and extended — 
up the Mississippi embayment as far as the mouth of the Ohio, cover- 
ing a belt extending from the sea margin 50 to 200, or even 500 miles 
into the interior of the continent. Often, the deposits form only a 
thin mantle, and away from the valleys ten or twenty feet may be 
_regarded as an average thickness. In the valleys, the accumulations 
reach 120 feet, and toward*the mouth of the Mississippi, 200 feet or 
more. But the formation has been degraded to an enormous extent by 
erosion, which has removed it from broad areas, leaving only patches 
to mark its former extension. 3 

In an introductory chapter, the author has given us an excellent 
description of the physiography of the coastal plain and of the various 
geological series in contact with the Lafayette formation. On the Atlan- 
tic border, the interior of the coastal plain is sharply defined by the 
margin of the Piedmont plateau, generally characterized by Archean 
rocks. This margin is the “fall line,” or location of the last great 
rapids in the descent of the rivers to the sea. Below this line, the 
streams, which generally cross the plains, are more or less navigable. 
The interior margin of the Gulf coastal plain is less sharply defined, as 
it trends across the termination of many different formations of vary- 
ing characteristics. This same coastal plain extends seaward to the margin 
of the continental shelf, which is now submerged and extends far sea- 
ward of the present coast. . ; 

The geology of this plain presents a varied study. Generally 
speaking, the Potomac (or Tuscaloosa) or later Cretaceous deposits 
form the interior margin of the belt. This basement is succeeded by 
many stages of the higher Cretaceous, Eocene, and Miocene accumu- 
lations, although the succession is not everywhere complete. No 
marine fossils higher than the middle Miocene are known on the 


REVIEWS. 437 


coastal plain, except at two or three localities. The topography of all 
of these formations was greatly modified by erosion during interven- 
ing periods of high level of the land, but in general, the successive 
formations were planed: nearly to base level before the succeeding 
deposits were laid down. ‘This was the condition before the Lafayette 
epoch, and the seaward slope of the country was more gradual than 
at present, although the continent was high enough to allow the 
submerged continental shelf to be a sub-aérial plain. Then came 
the extensive subsidence and seaward tilting, which allowed the 
invasion of oceanic waters over the coastal plain, so as to permit of 
the deposition of the loams even upon the margin of the Piedmont 
plateau. This subsidence was unequal, least in the region of Cape 
Hatteras, greater along the South Carolina axis, again diminished in 
the Gulf region, and greatest along the Rio Grande. The author 
regards all of these Lafayette deposits as having accumulated at sea 
level from the land wash brought down by the rivers. Although 
devoid of marine life, so far as known, this seems the most rational 
explanation, although the physical characters are very different from 
those of the earlier Tertiary or Mesozoic deposits, which were laid 
down after submergence with less decided seaward tilting. 

Mr. McGee regards the duration of the epoch of subsidence as 
short. The succeeding elevation, which carried the country from 100 
to 1,000 feet above tide, he regards as much longer. This uplift 
was not uniform, probably only 100-300 feet at Cape Hatteras, and 
1,000 feet at the mouth of the Mississippi, but in undulations such 
as characterized the previous subsidence; where the greatest depres- 
sion had taken place, there the greatest elevation followed along the 
same axes. Moreover, it is apparent from the intensity of erosion that 
the elevation was greater along the Appalachian and Cumberland 
plateaus than along the coast, giving greater slope to the rivers than at 
present. This elevation was unquestionably of long duration and the 
erosion enormous, removing from the valleys a large proportion of 
the accumulations of the preceding epochs and cutting through them 
to depths of 150 feet and upward, and to widths of 10 and 20 miles, 
even 100 miles in the case of the Mississippi. ‘This the author empha- 
sizes, giving great prominence to the geomorphy from which the 
post-Lafayette elevation is deduced. 

After this long-continued period of degradation, the continent 
subsided, but not so much as during the Lafayette days, and during 


438 THE JOURNAL OF GEOLOGY. 


this subsidence the Columbia formation was deposited. Some of its 
characters are similar to those of the Lafayette, and indeed the latter 
deposit may often be mistaken for the earlier, where unconformity is 
not apparent. The Columbia formation covered the lower half of the 
coastal plain, and partly filled the great valleys which thus became 
estuaries. ‘These deposits form the ‘‘ second bottoms” of many of the 
coastal rivers, particularly on the Gulf slope. In short, the Columbia 
formation of the South is largely the Lafayette made over, though in 
the North its materials grade into those of the glacial period. 

Following the Columbia submergence the continental margin again 
rose, even to an altitude above that of modern times, to such an extent 
as to permit of the clearing out of the valleys to a considerable extent ; 
including those now submerged along the oceanic plateau. Then fol- 
lowed a subsidence to modern conditions. This post-Columbia eleva- 
tion did not last nearly so long as the post-Lafayette, for 90 per cent. 
-of the accumulations still remain. 

The altitudes at which the Lafayette deposits are now found 
vary. In Maryland they occur at 500 feet; southward they decline 
so that. at Hatteras they occur at roo—200 feet. Along the axis of 
greatest oscillation in South Carolina the formation rises to 800 feet, 
but again descends southward so that north of Mobile Bay they rise 
only 500 feet above tide. Again in Illinois and Arkansas, the loams 
rise to only 350 and 250, whilst they culminate at 1,000 feet along the 
Rio Grande. But as river terraces of the streams emptying into the 
Lafayette sea, the reviewer has met with the extension of the formation 
in the southern Appalachian at 1,500 to 2,000 feet, thus supporting the 
author’s conclusions as to the greater magnitude of terrestrial undula- 
tion in the mountain regions than along the coast. 

At Cape Hatteras, the Columbia deposits now rise only 25 feet 
above tide, but they increase to 300 feet in altitude to the north and 
again southward, so that in South Carolina they rise to 650 feet. 
Again they decline to 25 feet above the Gulf in Mobile Bay. Farther 
southwestward their present elevation is from 100 to 200 feet. 

The meager flora of the Lafayette has both Cretaceous and Pleisto- 
cene features, and the more meager fauna represents the entire 
Neocene. The Columbia is regarded as the earliest Pleistocene, and 
the Lafayette as the later Pliocene, though the author groups it with 
the Miocene and small areas of marine Pliocene, the whole making the 
American Neocene. Its biological relations are not known ; it is by 


REVIEWS. 439 


its physical characters that the Lafayette formation has been investi- 
gated and largely explained. 

The author of ‘The Lafayette Formation” has made one of the 
most important recent contributions to geological science. Besides 
his contribution to the geology of an enormous area, the principles 
of geomorphy are emphasized, and the interpretation of the conti- 
nental changes of the later Tertiary days are set forth in an original 
manner, forming one of the most interesting chapters in dynamical 
geology. 

The maps are particularly worthy of attention. The first repre- 
sents the physiography of the coastal plain, and its relations both with 
the higher land area and deeper oceanic depression. ‘The next is a 
colored map showing the distribution of the Lafayette formation and 
the overlying Columbia. The third map shows the continental area 
during the Lafayette subsidence ; it is both a topographical and hydro- 
graphical chart of the physical features of land and sea when 250,000 
square miles of the southeastern part of the continent was submerged. 
It is of special interest. Then follows the topographical map of the 
high continent during the post-Lafayette elevation, when the conti- 
nental region was expanded by 100,000 miles or more in excess of 
that of modern times. The last map shows the continental contraction 
during the Columbia period—and a very strange looking map it is 
with the land margin dissected by numerous estuaries, scores or 
hundreds of miles in length, resulting from the submergence of the 
great valleys of the south in connection with the tilting of the land 
toward the South Carolina axis of oscillation. 

Although this work was commenced by others, yet the extension 
and digestion of the whole belongs to the author, and it is a remark- 
ably meritorious work. But in the study of geomorphy, and of the 
most interesting continental changes, the work is almost entirely 
original. The whole forms one of the most complete, yet peculiar, 
chapters of American geology. This review is only sufficient to call 
attention to a very suggestive report in which, hqwever, there are still 
some questions left open. The author is to be congratulated on having 
taken up such an important and interesting but little known subject, 
and for working it out to such a degree of completion. 

J. W. SPENCER. 


440 THE JOURNAL OF GEOLOGY. 


Elementary Meteorology. By Wtti1AM Morris Davis, Pro- 
fessor of Physical Geography in Harvard College. Bos- 
Odes lWls Sey DANG Ginnica Coy Eublishers,) S18 o47mmpp: 
XII.+355. 


THE announcement, made some months ago, that Prof. Davis was 
about to publish a work on meteorology, was hailed with satisfaction 
by all those interested in this branch of natural science. The book, 
which has recently been issued by Ginn & Co., presents the condensed 
results of the author’s reading, observation, and teaching during the 
last fifteen years. Since it has been prepared by one who is not only 
eminent as an original investigator, but also as an experienced teacher, 
it is scientific in its treatment, fully in accord with the latest advances in 
meteorology, and, at the same time, well fitted for the use of college 
students of the more advanced years. In so far as the experience of 
-the writer goes, this book would seem to be better adapted to the 
abilities of juniors and seniors of the majority of our colleges than 
to the “later years of a high-school course, or the earlier years of a 
college course,’ as the author suggests in the preface. 

The plan of the book is stated by the author at the outset, as fol- 
lows: ‘The origin and uses of the atmosphere are first considered, 
with its extent and arrangement around the earth. Then, as the winds 
depend on differences of temperature over the world, the control of 
the temperature of the atmosphere by the sun is discussed, and the 
actual distribution and variations of temperature are examined. Next 
follows an account of the motions of the atmosphere in the general 
and local winds; in the steady trades of the torrid zone, and in the 
variable westerly winds of our latitudes. The moisture of the atmos- 
phere is then studied with regard to its origin, its distribution, and its 
condensation into dew, frost, and clouds. After this, we are led to 
the discussion of those more or less frequent disturbances, which we 
place together under the name of storms; some of them being large, 
like the great cyclones or areas of low pressure on our weather maps ; 
some of them very small, like the destructive tornadoes. The effect of 
these storms and of other processes in the precipitation of moisture as 
rain, snow, and hail is next considered. Closing chapters are then 
given to the succession of atmospheric phenomena that ordinarily fol- 
low one another, on which our local variations of weather depend, 
together with some account of weather prediction; and another on 


REVIEWS. 441 


the recurrent average conditions that we may expect, in successive 
seasons, repeated year after year, which we call climate.” 

The above statement gives an idea of the scope and method of 
treatment of the subject. There are a few points, however, which 
deserve more particular mention. In chapter III., the distribution 
over the earth of the insolation, or radiant energy received by the earth, 
is discussed, and by means of a very ingenious diagram, the amount 
of insolation for all latitudes for each month of the year is graphic- 
ally shown. A detailed discussion of the various processes of absorb- 
tion, conduction, radiation, and convection, by means of which the 
atmosphere gains and loses heat, is given. In the course of this the 
author takes exception to the statement, so common in most physical 
geographies, in which the atmosphere is “compared to a trap which 
allowed sunshine to enter easily to the earth’s surface, but prevented 
the free exit of radiation from the earth.” In reality, the coarse- 
waved radiation from the earth passes out readily without great absorb- 
tion, either by the clear air or the water-vapor, which has been proved 
to be as poor an absorber as pure dry air. 

Again, the exact processes, by which convectional circulation is set 
up, are clearly brought out, and the incorrectness of such loose state- 
ments, as “the air is heated and rises, and the cold air rushes in from 
either side to fill the vacuum thus formed,” is emphasized. 

A general review of the distribution of pressures and the circula- 
tion of the winds shows the student two particulars, in which the 
expected arrangement of pressures and motions according to the 
theory of convection, as applied to the origin of winds, are contra- 
dicted by the facts. The polar pressures are high, not low, the high- 
est pressures occur around the tropics, where intermediate pressures 
were expected, and the winds do not follow the gradients, but are 
systematically deflected. Either the convection theory is fundament- 
ally wrong as an explanation for the winds, or it needs to be supple- 
mented by some factors up to this time unconsidered. This fact the 
author brings clearly to the mind of the pupil, who is then led to see 
that, perhaps, the oblique course of the winds may account for the 
distribution of pressures at the poles and the tropics. The cause 
of the oblique course is found in the deflecting influence of the 
earth’s rotation. It is proportionate to the velocity of motion, and 
increases from zero at the equator to a maximum value at either pole, 
but it does zo¢ depend upon the direction in which the body is mov- 


442 THE JOURNAL OF GEOLOGY. 


ing. In this connection, the author points out another error found in 
many text-books, namely that the oblique course of the winds is due 
to a lagging behind, as they move from regions of less to those of 
greater rotary velocity, and, therefore, that winds traveling due east 
would not be deflected at all. As was clearly shown by Ferrel, many 
years ago, both the explanation and its corollary are wrong, although 
they have appeared in many text-books, even of recent date. 

Following the discussion of a competent theory for the general cir- 
culation of the winds, there is given a systematic account of the dif- 
ferent members of the circulation, and a classification of winds accord- 
ing to cause into (1) planetary, (2) terrestrial, (3) continental, (4) land 
and sea breezes, (5) mountain and valley breezes, (6) cyclones and 
other storms, (7) eclipse winds, (8) landslide and avalanche blasts, (9) 
tidal breezes, (10) volcanic storms. 

Chapter X., treating of cyclonic storms and winds, is one of the 
* most interesting and valuable in the book. ‘The tropical cyclones are 
first considered. ‘The evidence of convectional action in these cyclones 
is considered, and it is shown that their distribution both in time and 
place points strongly to the theory that they originate through the 
overturning of great masses of air, due to unequal heating. But it is 
clearly pointed out to the pupil that it has not yet been directly shown 
that the temperature of the cyclonic mass is higher than that of the 
surrounding atmosphere at corresponding altitudes, a condition which, 
of course, must be satisfied before convection can take place. If this 
shall, hereafter, be shown zo¢ to be the case, the convectional theory 
will have to be abandoned. 

In points like this, Prof. Davis’ book is particularly good, for, all 
along, he has stated clearly not only what is certainly known, what is 
probable, and what is doubtful, but also what is not known. ‘This 
prevents the student from forming misconceptions of the subject, or 
dropping into loose habits of thought. 

The extra-tropical cyclones are closely compared with the tropical 
cyclones, and their points of likeness and difference shown. ‘Two 
theories for their origin are discussed, and lines are indicated along 
which the rival theories may, some day, be tested, but here again, the 
fact is emphasized that much is not yet known, and that positive didactic 
statements are to be avoided. 

Space will not permit even a brief mention of many other points 
to which we should like tocall attention. The subjects of thunderstorms, 


REVIEWS. 443 


rainfall, weather, and climate receive careful consideration. The text 
is illustrated by many maps and diagrams, of which a number are 
original. ‘The generalized charts, showing the winds of the Atlantic 
and Indian Oceans, taken from the atlas of the German Naval Obser- 
vatory, are particularly valuable. But a few of the diagrams, although 
showing clearly what they were intended to represent, fall short of 
the standard of artistic excellence set by the others. 

The value of this book lies, if in some things more than in others, 
in the logical treatment of the subjects, the frequent turning aside 
from the discussion for the purpose of introducing additional facts in 
order to correct, modify or substantiate hypotheses, and the clear 
discrimination, between facts, well-established theories, and working 
hypotheses. The pupil, who uses this book intelligently, will learn, 
not only many things about meteorology, but what is far more valu- 
able, true scientific methods of thought, study, and work. 

HENRY B. KUMMEL. 


ANALYTICAL ABSTRACTS OF CURRENT 
LITERATURE. 


SUMMARY OF CURRENT PRE-CAMBRIAN NORTH 
AMERICAN LITERATURE." 


Lawson? gives a résumé of the geology of Northeastern Minnesota adjac- 
ent to Lake Superior. Surrounding the Lake there are four geological prov- 
inces, from the top downward, the Potsdam, Keweenian, Animikie, and 
Archean. 

The Rocks of the Potsdam are flat-lying shaly sandstones, generally of a 
red color. 

The Keweenian occupies the entire Minnesota coast from Duluth to Grand 
Portage. The series consists in this area of a well stratified series of volcanic 
flows, having a gentle lakeward dip,which does not generally exceed 10°. 
The sedimentary formations are represented in the series, but occupy less 
than one-half per cent of the coast line. The lavas are largely vesicular or 
amygdaloidal in character, and in those of acid composition in which the 
vesicular structure is not so well developed are numerous irregular joints. 
The series has been invaded by many later intrusive masses, which occur as 
nearly vertical dikes, or more commonly as injected sills which coincide with 
the planes of stratification of the bedded flows. Since the time of the out- 
flow of the Keweenian rocks, the strata have suffered comparatively little dis- 
turbance, the prevalent lakeward dip being probably due to the attitude of the 
slopes upon which the lavas flowed, rather than entirely to a differential move- 
ment of once horizontal strata. The pre-Keweenian labradorite rocks exposed 
at a number of points were profoundly eroded before the Keweenian was 
deposited upon them, and they were presumably Archean. 

The Animikie rocks occupy the shore of the Lake from Grand Portage to 
Port Arthur. The series is composed altogether of sedimentary strata, and 
consists mainly of fine-grained sandstones, which are locally quartzites, car- 
bonaceous shales or slates, and in small part of cherts and jaspers, beds of 
carbonate of iron, hematite and magnetite, conglomerate, and occasional 
lenses of ‘non-ferruginous carbonate in the slates. Except in local instances 


tContinued from p. 118. 


2Sketch of the Coastal Topography of the North Side of Lake Superior with 
Special Reference to the Abandoned Strands of Lake Warren, by A. C. Lawson. In 
20th Annual Rep. Geol. & Nat. Hist, Sur., Minn. pp. 181-289. 


444 


AUINCSTIE VOT OAUIG, ABS IRA CIOS. 445 


the rocks have been disturbed very little from the horizontal, the average dip 
of the strata being in a southeasterly direction at an angle probably not 
exceeding 5 degrees. Intrusive rocks are abundantly present as sills lying 
parallel to the stratification, resembling contemporaneous beds, and as vertical 
dikes, some of which have been observed in continuity with the sills. Fault- 
ing is a common occurrence in the Animikie, many scarps being due primarily 
to this cause. 

The Archean shares the coast line with the Animikie and Keweenian from 
the vicinity of Port Arthur to the eastern end of Nipigon Bay, and beyond 
this point to the outlet of the lake is the dominant series. This complex con- 
sists of two divisions: 1) a great volume of profoundly altered sedimentary 
and volcanic rocks, characteristically schistose or in the form of massive green- 
stones, which have suffered intense disturbance, and which correspond to 
what has been designated the Ontarian system, and 2) immense batholites of 
irruptive gneiss and granite, which have invaded the rocks of the Ontarian 
system from below in the most irregular fashion, corresponding to that division 
of the Archean which is commonly recognized as Laurentian. These Lauren- 
tian rocks exhibit only to a very subordinate extent those evidences of dis- 
turbances and deformation which are so abundantly apparent in the schists 
which they have invaded. The Laurentian gneisses and granites occupy much 
more of the shore than do the metamorphic and schistose rocks of the Ontarian. 
Both divisions of the formation are cut by basic dikes, which, asarule, do not 
exceed 100 feet in width, and are vertical or nearly so. The Archean forms the 
basement upon which the Animikie rests in glaring unconformity, the actual 
superposition being observed at several points, with the Keweenian lying flat on 
the latter. Very frequently, however, the Keweenian reposes directly upon 
the Archean. 


Van Hise’ gives an historical sketch of the Lake Superior region to Cam- 
brian time. The five divisions of this region are the Basement Complex or 
Archean; The Lower Huronian, Upper Huronian and Keweenawan, the last 
three together constituting the Algonkian, and the Lake Superior Cambrian 
Sandstone. Each of these divisions are separated by unconformities. 

The Basement Complex consists mainly of granites, gneissoid granites, and 
of finely foliated dark colored banded gneiss or schist. The relations which 
obtain between the two divisions are frequently those of intrusion, the granites 
and gneissoid granites being the later igneous rocks. There is no evidence 
that any of the dark colored schists are sedimentary, but it is certain, if a 
massive granular structure be proof of an igneous origin, that a part of them 
are eruptive, for between the two are gradations. 


*An Historical Sketch of the Lake Superior Region to Cambrian Time, by C. R. 
Van Hise. In JOURN. OF GEOL., Vol. I, No. 2, pp. 113-128. With geological map. 


446 THE JOURNAL OF GEOLOGY. 


The well known characteristic rocks of the Lower Huronian are 1) con- 
glomerates, quartzites, quartz-schists, and mica-schists, 2) limestones, 3) 
various ferruginous schists, 4) basic and acid eruptives, which occur both as 
deep seated and as effusive rocks. The order given, with the exception of 
the eruptives, is the order of age from the base upward. In the Lower 
Huronian are placed the Lower Vermilion, Lower Marquette, Lower Felch 
Mountain, Lower Menominee, the cherty limestone formation of the Penokee 
district, and also probably the Kaministiquia series of Ontario, and the Black 
River Falls series of Wisconsin. 

The formations of the Upper Huronian are 1) a basement slate and 
quartzite, frequently bearing basal conglomerates, 2) an iron-bearing forma- 
tion, consisting originally of lean cherty carbonate of iron, calcium and mag- 
nesium, and 3) an upper slate. Associated with the sedimentaries in the 
Michigamme, Crystal Falls, and other districts, are great volcanic series, com- 
prising greenstones, agglomerates, greenstone conglomerates, volcanic ash, 
and amygdaloids. Where these occur the orderly succession is destroyed. 
Included in the Upper Huronian are the Penokee, Mesabi, Animikie, Upper 
Marquette, Upper Menominee, and Upper Felch Mountain districts. 

The Keweenawan consists of interstratified lavas, sandstones and con- 
glomerates. The lavas are prevalent at the lower part of the series; inter- 
stratifications of the two occur in the middle portions ; and the pure detritals 
exclude the volcanics in the upper portion of the series. 

The Lower Huronian is largely crystalline, the Upper Huronian semi-crys- 
talline, and the Keweenawan simply cemented. Locally along axes of intense 
plication, both the Lower Huronion and Upper Huronian have been trans- 
formed into completely crystalline schists. The Cambrian of Lake Superior 
is a horizontal sandstone, and rests unconformably upon all the preceding. 


Smyth™ describes a contact between the lower quartzite of the Lower 
Huronian and the underlying granite at Republic, Michigan. Below the 
lowest exposures of magnetite-actinolite-schist are, exposures of the lower 
quartzite, and below this, hanging upon the northern flank of the granite, is a 
conglomerate containing very numerous well rounded bowlders of granite 
and gneiss, identical with the rocks immediatiately below. It is concluded 
that this conglomerate from its position can not possibly belong to the Upper 
Huronian, and that it is a true basal conglomerate of the Lower Huronian. 


Winchell, N. H.,? gives the following as the general consensus of opinions 


™A contact between the Lower Huronian and the Underlying Granite in the 
Republic Trough, near Republic, Mich, by. H. L.. Smyth, JourN. oF GEOL., Vol. L., 
No. 3, pp. 268-274. 

2The Crystalline Rocks, by N. H. Winchell. In 20th Annual Rep. Geol. & Nat. 
Hist. Sur., Minn., 1891, pp. 1-28. 


ANALYTICAL ABSTRACTS. 447 


of several geologists as to the descending succession of the rocks of North- 
eastern Minnesota. 

1. Keweenawan or Nipigon series unconformably beneath rocks bearing 
the “ Dikellocephalus” fauna, and consisting of fragmental and eruptive beds, 
the upper portions being almost entirely red sandstones. 

2. Alternating beds of eruptive sheets and fragmental rocks. The frag- 
mentals are thin bedded slates, actinolite-schists, magnetitic jaspers, cherts and 
quartzites. The sheets are ordinary eruptives or pyroclastics. 


3. Immense quantities of true gabbro often bearing Titaniferous magnet- 
ite, are associated with contemporaneous felsites, quartz-porphyries and red 
granites. This gabbro includes several masses of the next older strata, par- 
ticularly the Pewabic quartzite. 

4. The Animikie. This series is characterized by a great quartzite associ- 
ated with the iron ores and cherts. The quartzite (Pewabic) lies unconform- 
ably on all the older rocks. It often is conglomeratic, bearing debris of the 
underlying formations. Within it is mingled volcanic tuffs from contempora- 
neous eruptions. The Pewabic quartzite includes that of Pokegama Falls 
on the Mississippi River, and of Pipestone County. In the vicinity of con- 
temporaneous volcanic disturbances its grain is fine, like jaspilite, and some- 
times it has acquired a dense crystalline structure from contact with the 
gabbro. 

5. The Keewatin. This isa volcanic series of great thickness, being com- 
posed mainly of volcanic tuffs, presenting more or less evidence of aqueous 
sedimentation, but conglomerates, graywackes, quartzitic schists, and glossy 
serpentinous schists are present. The Kawishiwin formation, apparently the 
upper member of the series, embraces the great bulk of the greenstones, 
chloritic schists, jaspers, and hematites. The iron ores are in lenticular lodes, 
and stand upright conformable with the general position of the rocks. 


6. The Keewatin series becomes more crystalline towards the bottom, and 
passes conformably into completely crystalline mica-schists and hornblende- 
schists, which are named the Vermilion series. The rocks are usually strati- 
form, contain magneticiron ore, and embrace some dark massive greenstone 
belts, in which no stratification bands are visible. 


7. The Laurentian. When not disturbed by upheaval the Vermilion 
schists pass into Laurentian gneiss, there being a gradual increase in the 
feldspathic and siliceous ingredients. Even after the Laurentian characters 
are apparently fully established, conformable bands of Vermilion schists 
reappear : from which it is plain that the base of the Vermilion is an uncer- 
tain plane, which can not be located exactly. This normal passage from the 
Vermilion to the Laurentian is frequently disturbed by the intrusion of 
numerous dikes of light colored granitic and basic rocks. These were both 
in a fluid state, the only non-fluid rocks being the schists which are embraced 


448 DHE, JOURNAL OF (GEOLOGY. 


within them in isolated pieces. Ina similar manner small areas of Lauren- 
tian granite, sometimes directly in contact with the schists, have the imper- 
fectly crystalline condition of the Keewatin. 

Nos. 3 and 4 are separable from No. 2 by divergence in dip and strike, 
as well as by a marked difference of lithology. There is consequently some 
evidence of unconformity between them. Below No. 4 is a great physical 
break, which separates Nos. 1, 2, 3, and 4 from 5, 6 and 7 throughout the Lake 
Superior region. This break is the greatest erosion interval which has been 
discovered in Palzozoic geology. 1, 2, 3, and 4 together constitute the 
Taconic, Nos. 5, 6, and 7 constitute the fundamental complex or Archean, 
which is a unit in its grander features. 

The structure and origin of the foregoing series are considered in some 
detail. It is concluded that stratification can always be discriminated from 
schistosity or slaty cleavage by the varying shades of color bands which sweep 
across the surface of the rocks, and by gradations in the kind and size of 
grains across the bands. These layers may vary from 1-16 of an inch to 
several inches or several feet across. 


Comments.—As used by the United States Geologists, Nos. 1, 2 and 3, are 
included inthe Keweenawan. These divisions and the break between 2 and 
3 are recognized by Irving, so that the difference is merely one of nomencla- 
ture. No. 4 is Upper Huronian; No. 5 is Lower Huronian; and Nos. 6 and 
7 are the Basement Complex or Archean. The break between the Lower 
Huronian and the Basement Complex is perfectly clear on the south shore of | 
Lake Superior, and is found by Lawson at the base of the Keewatin in 
Ontario. In Minnesota, Professor Winchell, on the contrary, regards the 
Keewatin as grading down into the underlying series. Many geologists would 
disagree with the statement that stratification can always be discriminated 
from schistosity or slaty cleavage by either of the criteria mentioned or by 
both combined. 


Grant,’ in 1893, publishes his note book, made on a trip in Northeastern 
Minnesota. The areas visited were those of the Kawishiwi river, Snow 
Bank lake, Kekequabic lake, and Saganaga lake. In the study of these 
areas there was no evidence found of a transition from semi-crystalline 
and crystalline schists into granite. On the other hand, abundant evidence 
was found of the eruptive nature of the granite rocks into the surrounding 
sediments. The gneissic and so-called bedded structure in the granitic rocks 
is not aS common as has been supposed, the structure usually being truly 
granitic. The Kawishiwi river and Snow Bank lake massive rocks are horn- 
blende syenites. The Saganaga rock is a coarse hornblende granite. That 


t Field Observations on Certain Granitic Areas in Northeastern Minnesota, by U. S. 
GRANT. In 20th Annual Rep. Geol. and Nat. Hist. Sur. Minn., pp. 35-110. 


ANALYTICAL ABSTRACTS. 449 


around Kekequabic lake is a pyroxene granite, and associated with it is 
peculiar pyroxene-granite-porphyry. The intrusive character of the granite is 
particularly well shown between Sec. 31 and 32, T. 63 N., R. 10 W., near 
Clearwater lake, and in the S. E. &% of the S.W. ¥% Sec. 26, T. 64 N., R. 9 
W., on the west shore of Snow Bank lake. Along the Kawishiwi river, the 
rocks mapped comprise gabbro, syenite, mica-schist, graywacke, etc.; green- 
stone and quartz-porphyry. The gabbro is the most recent, and covers part 
of the older rocks. The syenite is older than the gabbro, and is younger than 
the greenstone and mica-schist, both of which it cuts. The mica-schists, 
graywackes, etc., are vertical, and have a general east northeast strike. These 
have been formerly mapped as belonging to the Vermilion series, but there 
seems to be good reason for putting all of this type of, rock in the area 
mapped into the Keewatin. The greenstone is presumably of Keewatin age, 
and is probably younger than the mica-schists, graywackes, etc. Quartz 
porphyry dikes are found cutting the greenstones in several places, but they 
have not been seen in the other rocks in the immediate vicinity. 

Comments.—The conclusions of this report differ from the general succes- 
sion given by Professor Winchell in the fundamental point that there is no 
gradation between the granitic rocks and the metamorphosed sedimentary 
rocks. Also all of the metamorphosed sedimentary rocks are regarded as 
belonging to the Keewatin (Lower Huronian ?) while the Vermilion schists are 
not found. If there now exists in this area the original basement upon which 
the sedimentary rocks were deposited, this has not been found. It is of course 
possible that such a Basement Complex does not exist in the Kawishiwi river 
area, the one which was most closely studied, nor even in the entire region, 
but this is not thought probable. 


Winchell (H. V.)' describes the Mesabi iron range of Minnesota. The 
range extends from the Canadian boundary, a little south of west to the 
Mississippi river, a distance of 140 miles or more, but is concealed for a part 
of this distance by the later gabbro overflow. The succession of the Mesabi in 
descending order is: 


1. Gabbro unconformably on all the following................ Taconic. 
2, lilac slates Amini s500060606600000 5¢0000 800500 G0000c Taconic. 
3. Greenish siliceous slates and cherts...................--. Taconic. 
4. Iron ore and taconyte horizon..........------+.++ esses Taconic. 
5. Quartzite unconformable on 6 and 7................. 045. Taconic. 
6. Green schists of the Keewatin......................--%-- Archean. 
7. Granite or syenite of the Giant’s Range.................. Archean. 


The granite of the Giant’s Range is bounded on the north by a belt of 
crystalline mica-schists and hornblende-schists, and on the south seems to 


1The Mesabi Iron Range, by H. V. WINCHELL. In 20th Annual Rep. Minn. Geol. 
Sur., pp. 11-180. 


450 THE JOURNAL OF GEOLOGY. 


have a direct transition into the green schists of the Keewatin. The green 
schist has a nearly vertical cleavage. The schists do not always follow 
the course of the granite range. They are unconformably covered in many 
places by the quartzite. The quartzite never has a high dip. Near 
the base it contains peobles of quartz and granite, as well as jasper and 
greenstone, This quartzite is correlated with the Pewabic quartzite of the 
Gunflint lake, the Pokegama quartzite of the Mississippi river, that of Sioux 
Falls, South Dakota, and that of Baraboo, Wisconsin. Conformable with the 
quartzite is the iron ore and taconyte horizon. The strata are siliceous and 
calcareous, and are banded with oxide of iron in beds of variable length and 
thickness. The ore is sometimes magnetite and sometimes hematite. To the 
banded jaspery quartzite associated with the ore the term taconyte is applied. 
The greenish siliceous slates or cherts constitute a transition stage between 
the rocks of the iron horizon and the black slates. There is a considerable 
mixture of greenish material, apparently of eruptive origin. The greater part 
of the rock is a red, yellow, black, white, or green chert, sometimes having a 
thickness of 200 or 300 feet. It often has a peculiar brecciated appearance, 
having been shattered into angular fragments, and recemented by the same 
amorphous silica. The same fracturing is also visible in the iron ore. The 
siliceous slates and cherts pass upward into a carbonaceous argillite of great 
thickness, having a dip varying from the horizontal to 20° to the south or 
southwest. Locally the dip is as high as 45°, in which case the ore deposits 
lie close to the green schists. The gabbro flow is over all of the previous 
strata. The effect of the heat on the molten gabbro was to make the iron ore 
which already existed in the rocks hard and magnetic. There is good reason 
to believe that the iron ore deposits in their present condition have been prin- 
cipally formed since the gabbro overflow. The ore deposits occur as regular 
beds, which lie in almost their original positions, usually having a dip of less 
than 30° and passing into the jaspery quartzite or taconyte in three directions, 
and occasionally on all sides. The theory of Irving as to the origin of the 
Gogebic ores is partially adopted. The quartzite is impervious to surface 
infiltration. The ore is regarded as produced by chemical replacement of 
some mineral, chiefly silica, by oxide of iron. As evidence of this, all stages 
of the process may be seen. Iron carbonate is found in the Mesabi rocks, but 
it does not appear in sufficient quantity to permit the assumption that the 
source of the ore was originally a carbonate. The solvent for the silica was 
probably carbon dioxide, and its source may have been the atmosphere, the 
black slates, recently decaying vegetation, or the ore deposits higher up the 
hill. The silica removed from the location of the iron ores has been added to 
the grains of quartz in the quartzite, has been deposited as chalcedonic and 
flinty silica, and has been deposited in cracks and fissures in the slate, which 
lie at a lower elevation, but stratigraphically above the ore. The source of 


< ANALYTICAL ABSTRACTS. 451 


the iron is believed to have been chemical and mechanical oceanic deposits, 
which have simply concentrated in the present situation, perhaps from rocks 
now completely removed by erosion. The water which brought in the iron 
ore to supply the place of the silica taken away in solution followed the natural 
drainage courses, either the drainage slopes or else the joints. The Giant’s 
Range is regarded as having been uplifted at the time of the gabbro outflows, 
and to have been caused by them. 


Comments.—The succession of the Mesabi range is almost identical with 
that given by the reviewer for the Penokee-Gogebic district. At the base of 
the Penokee series constituting the basement complex are granite, syenite, 
and various green schists. These correspond to Nos. 6 and 7 of the Mesabi. 
Resting unconformably upon this basement complex is the quartz slate mem- 
ber, consisting largely of quartzite, corresponding to Winchell’s No. 5. Rest- 
ing conformably on the quartzite is the iron-bearing member, which has two 
main horizons, the lower carrying the ore bodies, and the other free from ore 
bodies. This iron-bearing formation of non-fragmental origin consists of 
cherts, slates, and jaspers, all more or less ferruginous. It evidently corres- 
ponds exactly to Winchell’s Nos. 3 and 4, his “‘taconyte”’ being a new name 
proposed for ferruginous chert, or what the miners call “soft ore jasper.” 
Overlying the iron-bearing member is the upper slate member, which is iden- 
tical in character with Winchell’s Animikie black slates. Unconformably 
upon the black slates is the Keweenawan series, which, in the Penokee area, 
has different characters in different places, but to which Winchell’s No. 1 
gabbro belongs. There thus appears to be absolute identity as to succession, 
and also the structural breaks occur in precisely the same horizons in the 
Penokee and Mesabi districts. The facts given as to the iron ores, apart from 
theory, correspond in nearly every respect with the occurrences in the Penokee 
district. The differences are that the basement impervious formation in the 
Mesabi range is not a dike rock, but the pitching quartzite alone. The source 
of the iron ore is said to be an oceanic deposit, but while the presence of iron 
carbonate is asserted, it is denied that it can be assumed that it has been 
present in sufficient quantity to furnish ore beds. The cherty iron car- 
bonate of the Gogebic range, the source of the ore, was a water deposited 
sediment. 

The presence of three like unconformable series in the Penokee and 
Mesabi districts, the identical succession of the iron-bearing series, the 
remarkable similarity of the rocks of each of the corresponding formations, 
and the nearly identical history of the ore-deposits, is a remarkable instance 
of like conditions prevailing simultaneously in a geological basin throughout 
a wide area. 


452 THE JOURNAL OF GEOLOGY. 


Hulst? gives a resumé of the general geology of the Menominee district as 
explained by Brooks, and gives detailed sections of several of the mines. 
The descending succession at the Millie Ore Body and Chapin Mine is as fol- 
lows : : 


Jasper 

Quartzite 

Quartzite and jasper K 

Quartzite, slate, and jasper 

Slate 

Quartzite and slate 

Quartzite and jasper 

Banded ore, containing Mil- 
lie Ore Body 

Quartzite and slate 


Quartzite | 


2 140 feet. 


- 300 feet 


Sine 5 = 55 feet. 


Jasper - - - - - - 170 feet. 
Ore body 

Gray slate - - = - - - 75 feet. 
Ore | 

Gray slate 

Jasper | 

Gray slate 

Jasper G r - - 185 feet. 
Gray slate 

Jasper | 


Ore 
Gray slate 
Limestone 


The descending succession in the Pewabic Mine is as follows: 


Jasper and ore, containing : < 215 feet. 


Pewabic Ore Body 
Gray slates - - - = - - 112 feet. 
Quartz 
Gray slate 
Quartzite - - - - - - Titec ts 
Quartz and slate 
Slate conglomerate - - - - 50 feet. 
Red slate - - - - - Te ete 
Quartz and gray slate 
Quartzite 
Quartz and sand 
Slate conglomerate ’ 
Quartz conglomerate - - - = 116 feet. 
Red slate 
Jasper 
Red, gray slate 
Limestone. 


«The Geology of that Portion of the Menominee Range East of Menominee river, 
Nexson P. Hurst. In Proceedings Lake Superior Mining Institute for March, 1893, 


pp. 19-29. 


ANALYTICAL ABSTRACTS. 453 


The ore bodies are found in beds of banded lean jasper, which is 
always an invariable associate of the richer ore, and it may occur anywhere 
within the jaspery horizon. The rich ore often appears to be a part and par- 
cel of the general stratification of the lean ore encompassing it. Not infre- 
quently one finds spots which are apparently in the transition state from the 
lean jaspery ore, as though the ore body was charged with a solution, which 
was gradually dissolving out the silica from the adjacent jasper. There is 
invariably a notable pitch to the ore bodies, and it is generally to the west at 
an angle of from 30° to 50°. Connected with some of the ore bodies are well 
defined hanging or foot-walls of so-called soapstone, but often when there are 
no well-defined walls, the ore body being found in the jasper, the ore is quite 
sure to carry aminimum of phosphorus, as exemplified at the Millie, Pewabic, 
Cyclops, Aragon, and S. E. Vulcan mines. The productive portions of the 
range appear to be located at the points where the formation has been faulted, 
eroded deeply, or sharply folded. 


Comments.—The sections give additional evidence that in the Menominee 
district, as in the Marquette, there are two unconformable series. The Chapin, 
Ludington, and Hamilton appear to belong to the Lower Huronian. The 
horizon of quartzite, slate and conglomerate is evidently the basal conglomerate 
of the Upper Huronian. The Mille, Pewabic, and similar ore bodies, are in 
the Upper Huronian. That the ore bodies occur in disturbed areas, and fre- 
quently rest upon soapstone or other impervious formations, accords perfectly 
with what has been previously ascertained as to the manner of concentration 
of the Lake Superior iron ores. 


Van Hise? gives the following as the ascending succession in the iron-pro- 
ducing part of the Marquette district : (1) Basement Complex, consisting of 
granites, gneisses, schists, and greenstone-conglomerates, the whole intricately 
intermingled, and the schists intruded by the granites and gneissoid granites ; 
unconformity : (2) Lower Marquette series, having at its base-a conglomerate 
and quartzite formation, upon which rests an iron-bearing formation; uncon- 
formity ; Upper Marquette series, which looked at broadly is a great shale, 
mica-slate and mica-schist formation, but it often has at its base quartzites and 
conglomerates, and several hundred or a thousand feet from its base an iron- 
bearing formation similar to that of the Lower Marquette series. Included 
within both the Lower and Upper Marquette series are many basic intrusive 
dikes and bosses of diabase, and also contemporaneous volcanics, which are 
largely tufaceous 

At the east end of the Marquette district is the Mesnard series, the position 
of which has not as yet been determined. 


The Succession in the Marquette Iron District of Michigan, by C. R. VAN HISsE. 
Bull. Geol. Soc. of Am., Vol. V., 1893, pp. 5-6. 


ASA THE JOURNAL OF GEOLOGY. 


Van Hise’ describes the Huronian volcanics south of Lake Superior. 
These include both lavas and tufas interstratified with each other and with 
contemporaneous clastics. Among the lavas are amygdaloids, the amygdules 
of which are in certain cases jasper similar to that of the iron formation 
adjacent, and believed to have been formed at the same jasper forming period. 
The volcanics are much more altered than those of the Keweenawan. They 
are found in various places, but the most extensive areas are in the Gogebic 
district west of Gogebic lake, and in the Michigamme district north of Crystal 
Falls. In the first locality the series is 7,000 or 8,000 feet in thickness. This 
great mass of material was piled up, while to the west 700 to 800 feet of the 
sediments of the iron-bearing formation were accumulating. In this district, 
therefore, at the same time there was being deposited the ordinary sediments 
of the area and locally a volcanic series of a wholly different character. 


"Bayley describes actinolite-magnetite-schist from the Mesabé range of 
Minnesota. This rock differs from the corresponding schists of the Penokee 
_ series only in that quartz is rare and hematite is absent. 

C. R. VAN HISE. 


tThe Huronian Volcanics South of Lake Superior, by C. R. VAN HisE. Bull. 
Geol. Soc. of Am., Vol. IV., pp. 435-36- 


2 Actinolite-magnetite-schists from the Mesabé Iron Range, in Northeastern Min- 
nesota, by W. S. BAyLEy. Am. Jour. of Sci. Vol. XLVI., No. 273, Sept., 1893, pp. 
176-180. 


219 


NIAN INSTITUTION LIBRARIES