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ons,

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—!. 7
CONTOUR AND GLACIAL MAP

OE THE

SCALE OF MILES = = BRITISH ISLES
ty 20 20 Cr =} =
ELEVATIONS, =
[5 From Sea Level to 250 Feet:
EBB] 250 to 500 Feet.
——— BBB 500 to 2,000 Feet.
HB Above.2,000 Reet.

HhrtbHH Track of Lake DistrictRocksother ||
than Shap Granite. H
‘Track of Ailsa Craig Granite.
‘Track of Galloway Granites.
++ + + +Shap Granite.
<1l=11—|/= Track of Welsh Rocks.
————Inilcate the Boundaries of Ice-

Streams or the position of
Moraines.

borough Head
Bridlington-
Si

TALE OF WIGHT -—zZ
pS

ee Z
Torquay —-y5~FATHOM LINE ii
q 20F (Oe

29-FATHOW.
S A,
Ve

BTAUTHERS & 60.W.¥. le
Longitude Greenwich

————

:

CONTOUR AND GLACIAL MAP

OF THE

BRITISH ISLES

— > =
>

THE INTERNATIONAL SCIENTIFIC SERIES

of | MAN AND
THE GLACIAL PERIOD

BY

G. FREDERICK WRIGHT
DD he DEB. GesrA.

PROFESSOR IN OBERLIN THEOLOGICAL SEMINARY
FORMERLY ASSISTANT ON THE UNITED STATES GEOLOGICAL SURVEY
AUTHOR OF THE ICE AGE IN NORTH AMERICA.

LOGIC OF CHRISTIAN EVIDENCES, ETC.

WITH AN APPENDIX ON TERTIARY MAN
By PROF. HENRY W. HAYNES

BU el Webi US ERATE nD

SECOND EDITION

NEW YORK
D. APPLETON AND COMPANY
1895

CopyRicHT, 1892, Fit
By D. APPLETON AND COMPANY.

ELECTROTYPED AND PRINTED
AT THE APPLETON PREsS, U.S. A.

TO

JUDGE C. C. BALDWIN

PRESIDENT OF THE WESTERN RESERVE HISTORICAL SOCIETY
CLEVELAND

THIS VOLUME IS DEDICATED

IN RECOGNITION OF
HIS SAGACIOUS AND UNFAILING INTEREST IN

THE INVESTIGATIONS WHICH HAVE MADE IT POSSIBLE

PREFACE TO THE SECOND EDITION.

SINCE, as stated in the Introduction (page 1), the
plan of this volume permitted only “a concise presenta-
tion of the facts,” it was impossible to introduce either
full references to the illimitable literature of the subject
or detailed discussion of all disputed points. The facts
selected, therefore, were for the most part those upon
which it was supposed there would be pretty general
agreement.

The discussion trpon the subject of the continuity of
the Glacial period was, however, somewhat elaborate (see
pages 106-121, 311, 324, 332), and was presented with
excessive respect for the authority of those who maintain
the opposite view ; all that was claimed (page 110) being
that one might maintain the wnity or continuity of the
Glacial period “ without forfeiting his right to the respect
of his fellow-geologists.” But it already appears that
there was no need of this extreme modesty of statement.
On the contrary, the vigorous discussion of the subject
which has characterized the last two years reveals a de-
cided reaction against the theory that there has been more
than one Glacial epoch in Quaternary times; while there
have been brought to ight many most important if not
conclusive facts in favour of the theory supported in the
volume.

In America the continuity of the Glacial period has
been maintained during the past two years with impor-

Vill MAN AND THE GLACIAL PERIOD.

tant new evidence, among others by authorities of no less
eminence and special experience in glacial investigations
than Professor Dana,* Mr. Warren Upham,t and Profess-
or Edward H. Williams, Jr.{ Professor Williams’s inves-
tigations on the attenuated border of the glacial deposits
in the Lehigh, the most important upper tributary to the
Delaware Valley, Pa., are of important significance, since
the area which he so carefully studied lies wholly south of
the terminal moraine of Lewis and Wright, and belongs
to the portion of the older drift which Professors Cham-
berlin and Salisbury have been most positive in assign-
ing to the first Glacial epoch, which they have main-
tained was separated from the second epoch by a length
of time sufficient for the streams to erode rock gorges in
the Delaware and Lehigh Rivers from two hundred to
three hundred feet in depth.* But Professor Williams has
found that the rock gorges of the Lehigh, and even of its
southern tributaries, had been worn down approximately
to the present depth of that of the Delaware before this
earliest period of glaciation, and that the gorges were
filled with the earliest glacial débris.

A similar relation of the glacial deposits of the atten-
uated border to the preglacial erosion of the rock gorges
of the Alleghany and upper Ohio Rivers has been brought
to light by the joint investigations of Mr. Frank Leverett
and myself in western Pennsylvania, in the vicinity of

—

* American Journal of Science, vol. xlvi, pp. 327, 330.

+ American Journal of Science, vols. xlvi, pp. 114-121; xlvii, pp.
308-365 ; American Geologist, vols. x, pp. 339-862, especially pp.
361, 362; xili, pp. 114, 278; Bulletin of the Geological Society of
America, vol. v, pp. 71-86, 87-100.

+ Bulletin of the Geological Society of America, vol. v, pp.
13-16, 281-296 ; American Journal of Science, vol. xlvii, pp. 33-86.

# See especially Chamberlin, in the American Journal of Sci-
ence, vol. xlv, p. 192; Salisbury, in the American Geologist, vol. x1,
p. 18.

=

PREFACE TO THE SECOND EDITION. 1X

Warren, Pa., where, in an area which was affected by only
the earliest glaciation, glacial deposits are found filling
the rock channels of old tributaries to the Alleghany to a
depth of from one hundred and seventy to two hundred
and fifty feet, and carrying the preglacial erosion at that
point very closely, if not quite, down to the present rock
bottoms of all the streams. ‘This removes from Professor
Chamberlin a most important part of the evidence of a
long interglacial period to which he had appealed ; he
having maintained* that “the higher glacial gravels
antedated those of the moraine-forming epoch by the
measure of the erosion of the channel through the old
drift and the rock, whose mean depth here is about three
hundred feet, of which perhaps two hundred and fifty
feet may be said to be be rock,” adding that the “ exca-
vation that intervened between the two epochs in other
portions of the Alleghany, Monongahela, and upper Ohio
valleys is closely comparable with this.”

These observations of Mr. Leverett and myself seem
to demonstrate the position maintained in the volume
(page 218), namely, that the inner precipitous rock
gorges of the upper Ohio and its tributaries are mainly
pregiacial, rather than interglacial. The only way in
which Professor Chamberlin can in any degree break the
force of this discovery is by assuming that in preglacial
times the present narrow rock gorges of the Alleghany
and the Ohio were not continuous, but that (as Indicated
in the present volume on page 206) the drainage of various
portions of that region was by northern outlets to the
Lake Erie basin, leaving, on this supposition, the cols
between two or three drainage areas to be lowered in gla-
cial or interglacial time.

On the theory of continuity the erosion of these cols

* Bulletin 58 of the United States Geological Survey, p. 35;
American Journal of Science, vol. xly, p. 195.

x MAN AND THE GLACIAL PERIOD.

would have been rapidly effected by the reversed drainage
consequent upon the arrival of the ice-front at the southern
shore of the Lake Erie basin. During all the time elapsing
thereafter, until the ice had reached its southern limit, the
stream was also augmented by the annual partial melting
of the advancing glacier which was constantly bringing
into the valley the frozen precipitation of the far north.
The distance is from thirty to seventy miles, so that a
moderately slow advance of the ice at that stage would
afford time for a great amount of erosion before sufficient
northern gravel had reached the region to begin the filling
of the gorge.*

Mr. Leverett also presented an important paper before
the Geological Society of America at its meeting at Madi-
son, Wis., in August, 1893, adducing evidence which, he
thinks, goes to prove that the postglacial erosion in the
earlier drift in the region of Rock River, II]., was seven or
eight times as much as that in the later drift farther
north; while Mr. Oscar H. Hershey arrives at nearly the
same conclusions from a study of the buried channels in
northwestern Illinois. But even if these estimates are
approximately correct—which is by no means certain—they
only prove the length of the Glacial period, and not
necessarily its discontinuity.

At the same time it should be said that these investi-
gations in western Pennsylvania somewhat modify a por-
tion of the discussion in the present volume concerning
the effects of the Cincinnati ice-dam. It now appears that
the full extent of the gravel terraces of glacial origin in

* See an elaborate discussion of the subject in its new phases by

Chamberlin and Leverett, in the American Journal of Science, vol.
xlvii, pp. 247-288. :
_ +American Geologist, vol. xii, p. 314f. Other important evi-
dence to a similar effect is given by Mr. Leverett, in an article on
The Glacial Succession in Ohio, Journal of Geology, vol. i, pp. 129-
146.

PREFACE TO THE SECOND EDITION. xl

the Alleghany River had not before been fully appreciated,
since they are nearly continuous on the two-hundred-foot
rock shelf, and are often as muchas eighty feet thick. It
seems probable, therefore, that the Alleghany and upper
Ohio gorge was filled with glacial gravel to a depth of
about two hundred and fifty or three hundred feet, as far
down at least as Wheeling, W. Va. _ If this was the case, it
would obviate the necessity of bringing in the Cincinnati
ice-dam (as set forth in pages 212-216) to account direct-
ly for all the phenomena in that region, except as this ob-
struction at Cincinnati would greatly facilitate the silting
up of the gorge. ‘The simple accumulation of glacial
gravel in the Alleghany gorge would of itself dam up the
Monongahela at Pittsburg, so as to produce the results
detailed by Professor White on page 215.*

Of European authorities who have recently favoured the
theory of the continuity of the Quaternary Glacial period,
as maintained in the volume, it is enough to mention the
names of Prestwich,+ Hughes,{ Kendall,* Lamplugh, |
and Wallace,* of England; Falsan,( of France; Holst, {
of Sweden; Credner} and Diener,? of Germany; and

* Wor a full discussion of these topics, see paper by Professor
B.C. Jillson, Transactions of the Academy of Science and Art of
Pittsburg, December 8, 1893; G. F. Wright, American Journal of
Science, vol. xlvii, pp. 161-187; especially pp. 177, 178; The Popu-
lar Science Monthly, vol. xlv, pp. 184-198.

+ Quarterly Journal of the Geological Society for August, 1887.

¢ American Geologist, vol. viii, p. 241.

#* Transactions of the Leeds Geological Association for February
16, 1893.

| Quarterly Journal of the Geological Society, August, 1891.

4 Fortnightly Review, November, 1893, p. 633; reprinted in The
Popular Science Monthly, vol. xliv. p. 790.

) La Période glaciaire (Félix Alcan. Paris, 1889).

{ American Geologist, vol. viii, p. 242.

¢ Ibid., p. 241.

4 Ibid., p. 242.

xi MAN AND THE GLACIAL PERIOD.

Nikitin* and Kropotkin,+ of Russia.{ Among leading
authorities still favouring a succession of Glacial epochs
are: Professor James Geikie,* of Scotland; Baron de
Geer, || of Sweden; and Professor Felix Wahnschaffe,4
of Germany.

When the first edition was issued, two years ago, there
seemed to be a general acceptance of all the facts detailed
in it which directly connected man with the Glacial period
both in America and in Europe; and, indeed, I had stu-
diously limited myself to such facts as had been so long
and so fully before the public that there would seem to be
no necessity for going again into the details of evidence
relating to them. It appears, however, that this confi-
dence was ill-founded; for the publication of the book
seems to have been the signal for a confident challenge,
by Mr. W. H. Holmes, of all the American evidence, with
intimations that the European also was very likely equally
defective.) In particular Mr. Holmes denies the conclu-
siveness of the evidence of glacial man adduced by Dr.
Abbott and others at Trenton, N. J.; Dr. Metz, at Madi-
sonville, Ohio; Mr. Mills, at Newcomerstown, Ohio; and
Miss Babbitt, at Little Falls, Minn. ;

The sum of Mr. Holmes’s effort amounts, however, to

* Congrés International d’Archéologie, Moscow, 1892.

+ Nineteenth Century, January, 1894, p. 151, note.

t The volume The Glacial Geology of Great Britain and Ireland,
edited from the unpublished MSS. of the late Henry Carvill Lewis
(London, Longmans, Green & Co., 1894), adds much important evi-
dence in favour of the continuity of the Glacial epoch; see especially
pp. 187, 460, 461, 466.

* Transactions of the Royal Society of Edinburgh, vol. xxxvii,
Part I, pp. 127-150. .

|| American Geologist, vol. viii, p. 246.

4 Forschungen zur deutschen Landes und Volkskunde von Dr.
A. Kirchhoff. Bd. vi, Heft i.

( Journal of Geology, vol. i, pp. 15-37, 147-163; American Ge-
ologist, vol. xi, pp. 219-240.

PREFACE TO THE SECOND EDITION. X1ll

little more than the statement that, with a limited amount
of time and labour, neither he nor his assistants had been
able to find any implements in undisturbed gravel in any
of these places; and the suggestion of various ways in
which he thinks it possible that the observers mentioned
may have been deceived as to the original position of the
implements found. But, as had been amply and repeat-
edly published,* Professor J. D. Whitney, Professor Lucien
Carr, Professor N.S. Shaler, Professor F. W. Putnam, of
Harvard University, besides Dr. C. C. Abbott, all expressly
and with minute detail describe finding implements in the
undisturbed gravel at Trenton, which no one denies to be
of glacial origin. In the face of such testimony, which
had been before the public and freely discussed for several
years, it is an arduous undertaking for Mr. Holmes to
claim that none of the implements have been found in
place, because he and his assistants (whose opportunities for
observation had scarcely been one twentieth part as great as
those of the others) failed to find any. ‘To see how care-
fully the original observations were made, one has but to
read the reports to Professor Putnam which have from
time to time appeared in the Proceedings of the Peabody
Museum and of the Boston Society of Natural History,
and which are partially summed up in the thirty-second
chapter of Dr. Abbott’s volume on Primitive Industry.

In the case of the discovery at Newcomerstown, Mr.
Holmes is peculiarly unfortunate in his efforts to present
the facts, since, in endeavouring to represent the conditions
under which the implement was found by Mr. Mills, he
has relied upon an imaginary drawing of his own, in which
an utterly impossible state of things is pictured. The
claim of Mr. Holmes in this case, as in the other, is that

* Proceedings of the Boston Society of Natural History, vol. xxi,
January 19, 1881; Report of the Peabody Museum, vol. ii, pp. 44-
47; chap. xxxii of Abbott’s Primitive Industry ; American Geolo-
gist, vol. xi, pp. 180-184.

1

X1V MAN AND THE GLACIAL PERIOD.

possibly the gravel in which the implements were found
had been disturbed. In some cases, as in Little Falls
and at Madisonville, he thinks the implements may have
worked down to a depth of several feet by the overturning
of trees or by the decay of the tap-root of trees. A suffi-
cient answer to these suggestions is, that Mr. Holmes is
able to find no instance in which the overturning of trees
has disturbed the soil toa depth of more than three or
four feet, while some of the implements in these places
had been found buried from eight to sixteen feet. Kven
if, as Mr. Chamberlin suggests,* fifty generations of trees
have decayed on the spot since the retreat of the ice, it is
difficult to see how that would help the matter, since the
effect could not be cumulative, and fifty upturnings of |
three or four feet would not produce the results of one up-
turning of eight feet. Moreover, at Trenton, where the
upturning of trees and the decaying of tap-roots would
have been as likely as anywhere to bury implements,
none of those of flint or jasper (which occur upon the sur-
face by tens of thousands) are buried more than a foot in
depth; while the argillite implements occur as low down
as fifteen or twenty feet. This limitation of flint and jas-
per implements to the surface is conclusively shown not
only by Dr. Abbott’s discoveries, but also by the extensive
excavations at Trenton of Mr. Ernest Volk, whose collec-
_ tions formed so prominent a part of Professor Putnam’s
Paleolithic exhibit at the Columbian Exposition at Chi-
cago. In the village sites explored by Mr. Volk, argillite
was the exclusive material of the implements found in the
lower strata of gravel. Similar results are indicated by
the excavations of Mr. H. C. Mercer at Point Pleasant,
Pa., about twenty miles above Trenton, where, in the
lower strata, the argillite specimens are sixty-one times
more numerous than the jasper are.

* American Geologist, vol. xi, p. 188.

PREFACE TO THE SECOND EDITION. XV

To discredit the discoveries at Trenton and New-
comerstown, Mr. Holmes relies largely upon the theory
that portions of gravel from the surface had slid down to
the bottom of the terrace, carrying implements with them,
and forming a talus, which, he thinks, Mr. Mills, Dr. Ab-
bott, and the others have mistaken for undisturbed strata
of gravel. In his drawings Mr. Holmes has even repre-
sented the gravel at Newcomerstown as caving down into
a talus without disturbing the strata to any great extent,
and at the same time he speaks slightingly of the promise
which I had made to publish a photograph of the bank as
it really was. In answer, it is sufficient to give, first, the
drawing made at the time by Mr. Mills,-to show the gen-
eral situation of the gravel bank at Newcomerstown, in
which the implement figured on page 252 was found ; and,
secondly, an engraving from a photograph of the bank,
taken by Mr. Mills after the discovery of the implement,
but before the talus had obscured its face. ‘The imple-
ment was found by Mr. Mills with its point projecting
from a fresh exposure of the terrace, just after a mass,
loosened by his own efforts, had fallen away. ‘The gravel is
of such consistency that every sign of stratification disap-
pears when it falls down, and there could be no occasion
for a mistake even by an ordinary observer, while Mr.
Mills was a well-trained geologist and collector, making
his notes upon the spot.*

I had thought at first that Mr. Holmes had made out
a better case against the late Miss Babbitt’s discoveries at
Little Falls (referred to on page 254), but in the American
Geologist for May, 1894, page 363, Mr. Warren Upham,
after going over the evidence, expresses it as still his con-
viction that Mr. Holmes’s criticism fails to shake the force
of the original evidence, so that I do not see any reason for
modifying any of the statements made in the body of the

* The Popular Science Monthly, vol. xliii, pp. 29-39.

Xvi MAN AND THE GLACIAL PERIOD.

book concerning the implements supposed to have been
found in glacial deposits. Yet if I had expected such an
avalanche of criticism of the evidence as has been loosened,
I should at the time have fortified my statements by fuller

Y°Y “11S ONV *O'd BEeoal
t tt a Seanad Ret
BRESERS0rnR
I: SHES ER So0oEo
AVNVO OIHO iE Hat

Paleolith was found 148% feet from surface.

=
<

i)
ts 3
wl =
= 3
= &

Height of Terrace exposed, 25 feet.

Cc
LEVELAND AND
§ Poates, Engr’s, N.¥.

y

A| Dradle,

references, and should possibly have somewhat enlarged
the discussion. But this seemed then the less necessary,
from the fact that Mr. McGee had, in most emphatic
manner, indorsed nearly every item of the evidence ad-

KV11

PREFACE TO THE SECOND EDITION.

duced by me, and much more, in an article which appeared

in The Popular Science Monthly four years before the pub-

‘quo diary orgyTpoOR Vy oy} puNos STA ‘O 'M CLO SuTMOYsS

‘UMOISLOULOOMO NT UL OOVLIOT,

le

rtic

1s a

, 1888). In thi

ember

ion of the volume (Nov

icat
he had gai

]

the aqueo-glacial gravels of the Delaware

is In

But it
River at Trenton, which were laid down contemporane-

XVlll MAN AND THE GLACIAL PERIOD.

ously with the terminal moraine one hundred miles farther
northward, and which have been so thoroughly studied by
Abbott, that the most conclusive proof of the existence of
glacial man is found” (p. 23). “ Excluding all doubtful
cases, there remains a fairly consistent body of testimony
indicating the existence of a widely distributed human
population upon the North American continent during
the later Ice epoch” (p. 24). “ However the doubtful
cases may be neglected, the testimony is cumulative, parts
of it are unimpeachable, and the proof of the existence of
clacial man seems conclusive ” (p. 25).

In view of the grossly erroneous statements made by Mr.
McGee concerning the Nampa image (described on pages
298, 299), it is necessary for me to speak somewhat more
fully of this important discovery. The details concern-
ing the evidence were drawn out by me at length in two
communications to the Boston Society of Natural History
(referred to on page 297), which fill more than thirty pages
of closely printed matter, while two or three years before
the appearance of the volume the facts had been widely
published in the New York Independent, the Scientific
American, The Nation, Scribner’s Magazine, and the At-
lantic Monthly, and in Washington at a meeting of the
Geological Society of America in 1890. In the second
communication to the Boston Society of Natural History
an account was given of a personal visit to the Snake River
Valley, largely for the purpose of further investigation of
the evidence brought to my notice by Mr. Charles Francis
Adams, and of the conditions under which the figurine
was found. Among the most important results of this in-
vestigation was the discovery of numerous shells under the
lava deposits, which Mr. Dall, of the United States Geo-
logical Survey, identified for me as either post-Tertiary or
late Pliocene ; thus throwing the superficial lava deposits of
the region into the Quaternary period, and removing from
the evidence the antecedent improbability which would

PREFACE TO THE SECOND EDITION. x1x

bear so heavily against it if we were compelled to suppose
that the lava of the Snake River region was all of Tertiary
or even of early Quaternary age. Furthermore, the eyi-
dence of the occurrence of a great deddcle in the Snake
River Valley during the Glacial period, incident upon the
bursting of the banks of Lake Bonneville, goes far to re-
move antecedent presumptions against the occurrence of
human implements in such conditions as those existing at
Nampa (see below, pp. 233-237).

Mr. McGee’s misunderstanding of the evidence on one
point is so gross, that I must make special reference to it.
He says* that this image “is alleged to have been pounded
out of volcanic tuff by a heavy drill, . . . under a thick
Tertiary lava bed.” The statement of facts on page 298
bears no resemblance to this representation. It is there
stated that there were but fifteen feet of lava, and that
near the surface; that below this there was nothing but
aiternating beds of clay and quicksand, and that the lava
is post-Tertiary. The sand-pump I should perhaps have
described more fully in the book, as [ had already done in
the communication to the Boston Society of Natural His-
tory. It was a tube eight feet long, with a valve at the
bottom three and a half inches in diameter on the inside.
Through this it was the easiest thing in the world for the
object, which is only one inch and a half long, to be
brought up in the quicksand without injury.

The baseless assertions of Mr. McGee, involving the
honesty of Messrs. Kurtz and Duffes, are even less fortu-
nate and far more reprehensible. “It is a fact,” says Mr.
McGee, “that one of the best-known geologists of the
world chanced to visit Nampa while the boring was in
progress, and the figurine and the pretty fiction were laid
before him. He recognized the figurine as a toy such as
the neighbouring Indians give their children, and laughed

* Literary Northwest, vol. li, p. 275.

ex MAN AND THE GLACIAL PERIOD.

at the story ; whereupon the owner of the object enjoined
secrecy, pleading: ‘ Don’t give me away; I’ve fooled a lot
of fellows already, and I’d like to fool some more.’”*
This well-known geologist, on being challenged by Profess-
or Claypole + to give “a full, exact, and certified statement
of the conversation ” above referred to, proved to be Major
Powell, who responded with the following statement: “ In
the fall of 1889 the writer visited Boisé City, m Idaho
[twenty miles from Nampa]. While stopping at a hotel,
some gentlemen called on him to show him a figurine
which they said they had found in sinking an artesian
well in the neighbourhood, at a depth, if I remember
rightly, of more than three hundred feet. . . . When this
story was told the writer, he simply jested with those who
claimed to have found it. He had known the Indians
that live in the neighbourhood, had seen their children play
with just such figurines, and had no doubt that the little
image had lately belonged to some Indian child, and said
the same. While stopping at the hotel different persons —
spoke about it, and 1t was always passed off as a jest; and
various comments were made about it by various people,
some of them claiming that it had given them much
sport, and that a good many tenderfeet had looked at it,
and believed it to be genuine; and they seemed rather
pleased that I had detected the hoax.” {

Thus it appears that Major Powell has made no such
statement, at least in public, as Mr. McGee attributes to
him. It should be said, also, that Major Powell’s memory
is very much at fault when he affirms that there is a close
resemblance between this figurine and some of the chil-
dren’s playthings among the Pocatello Indians. On the

* American Anthropologist, vol. vi, p. 94; repeated by Mr. Mc-
Gee in the Literary Northwest, vol. ii, p. 276.

+ The Popular Science Monthly, vol. xlii, p. 778.

} Ibid., vol. xiii, pp. 322, 328.

PREFACE TO THE SECOND EDITION. Parad

contrary, it would have been even more of a surprise to
find it in the hands of these children than to find it among
the prehistoric deposits on the Pacific coast.

To most well-informed people it is sutficient to know
that no less high authorities than Mr. Charles Francis
Adams and Mr. G. M. Cumming, General Manager for
the Union Pacific line for that district, carefully inves-
tigated the evidence at the time of the discovery, and,
knowing the parties, were entirely satisfied with its suffi-
ciency. It was also subjected to careful examination by
Professor F. W. Putnam, who discerned, in a deposit of an
oxide of iron on various parts of the image, indubitable
evidence that it was a relic which had lain for a long time
in some such condition as was assigned to it in the bottom
of the well—all of which is detailed in the papers re-
ferred to below, on page 297.

Finally, the discovery, both in its character and con-
ditions, is in so many respects analogous to those made
under Table Mountain, near Sonora, Cal. (described on
pages 294-297), that the evidence of one locality adds
cumulative force to that of the other. The strata under-
neath the lava in which these objects were found are all
indirectly, but pretty certainly, connected with the Glacial
period.* No student of glacial archeology, therefore, can
hereafter afford to disregard these facts from the Pacific
coast.

OBERLIN, OHIO, June 2, 1894.

* See below, p. 349.

fon ACh Or ht Shins E HOt TiON:

THE wide interest manifested in my treatise upon The
Ice Age in North America and its Bearing upon the An-
tiquity of Man (of which a third edition was issued a year
ago), seemed to indicate the desirability of providing for
the public a smaller volume discussing the broader ques-
tion of man’s entire relation to the Glacial period in Ea-
rope as well as in America. When the demand for such
a volume became evident, I set about preparing for the
task by spending, first, a season in special study of the
lava-beds of the Pacific coast, whose relations to the Gla-
cial period and to man’s antiquity are of such great in-
terest ; and, secondly, a summer in Europe, to enable me
to compare the facts bearing upon the subject on both
continents.

Of course, the chapters of the present volume relating
to America cover much of the same ground gone over in
the previous treatise; but the matter has been entirely re-
written and very much condensed, so as to give due pro-
portions to all parts of the subject. It will interest some
to know that most of the new material in this volume was
first wrought over in my second course of Lowell Institute
Lectures, given in Boston during the month of March
last.

Iam under great obligations to Mr. Charles Francis
Adams for his aid in prosecuting investigations upon the
Pacific coast of America ; and also to Dr. H. W. Crosskey,

XX1V MAN AND THE GLACIAL PERIOD.

of Birmingham, England, and to Mr. G. W. Lamplugh, of
Bridlington, as well as to Mr. C. E. De Rance and Mr.
Clement Reid, of the British Geological Survey, besides
many others in England who have facilitated my investi-
gations; but pre-eminently to Prof. Percy F. Kendall, of
Stockport, who consented to prepare for me the portion
of Chapter VI which relates to the glacial phenomena
of the British Isles. I have no doubt of the general cor-
rectness of the views maintained by him, and little doubt,
also, that his clear and forcible presentation of the facts
will bring about what is scarcely less than a revolution in
the views generally prevalent relating to the subject of
which he treats.

For the glacial facts relating to France and Switzer-
land I am indebted largely to M. Falsan’s valuable com-
pendium, La Période Glaciaire.

It goes without saying, also, that I am under the deep- |
est obligation to the works of Prof. James Geikie upon
The Great Ice Age and upon Prehistoric Europe, and to
the remarkable volume of the late Mr. James Croll upon
Climate and Time, as well as to the recent comprehen-
sive geological treatises of Sir Archibald Geikie and Prof.
Prestwich. Finally, I would express my gratitude for the
great courtesy of Prof. Fraipont, of Liége, in assisting me
to an appreciation of the facts relating to the late remark-
able discovery of two entire skeletons of Paleolithic man
in the grotto of Spy.

Comparative completeness is also given to the volume
by the appendix on the question of man’s existence during
the Tertiary period, prepared by the competent hand of
Prof. Henry W. Haynes, of Boston.

I trust this brief treatise will be useful not only in
interesting the general public, but in giving a clear view
of the present state of progress in one department of the
inquiries concerning man’s antiquity. If the conclusions
reached are not as positive as could be wished, still it is

PREFACE TO THE FIRST EDITION. XXV

both desirable and important to see what degree of indefi-
niteness rests upon the subject, in order that rash specu-
lations may be avoided and future investigations directed
in profitable lines. :

G. FREDERICK WRIGHT.
OBERLIN, Onto, May 1, 1892.

CONTENTS.
@HIMEPALBI Riel
PAGES
INTRODUCTORY 1-8
GHAPRTER If
EXIsTInG GLACIERS 9-42
In Europe; in Asia; in Oceanica; in South America;
on the Antarctic Continent; in North America.
CHIP AE ER ehh:
GLACIAL MorTion 43-50
CHARTHR Tv:
Signs oF PAST GLACIATION . 51-65
CEP AE Rave
ANCIENT GLACIERS IN THE WESTERN HEMISPHERE 66-128
New England; New York, New Jersey, and Pennsyl-
vania; the Mississippi Basin; west of the Rocky
Mountains.
CHAPTER VI.
ANCIENT GLACIERS IN THE EASTERN HEMISPHERE . . 129-192

Central and Southern Europe; the British Is}les—the
Preglacial Level of the Land, the Great Glacial Cen-
tres, the Confluent Glaciers, the Hast Anglian Glacier,
the so-called Great Submergence ; Northern Europe ;
Asia; Africa.

XXVIll MAN AND THE GLACIAL PERIOD.

CEAE UE Revell:
PAGES
DRAINAGE SYSTEMS IN THE GLACIAL PERIOD : ; . 193-241

In America—Preglacial Erosion, Buried Outlets and
Channels, Ice-dams, Ancient River ‘Terraces; in
Kurope.

CHAPTER VIII.

Rextics oF MAN IN THE GLACIAL PERIOD . f E . 242-301

In Glacial Terraces of the United States; in Glacial
Terraces of Europe; in Cave Deposits in the British
Isles; in Cave Deposits on the Continent; Extinct
Animals associated with Man; Earliest Man on the
Pacific Coast of North America.

CHAPTER IX.

THE CAUSE OF THE GLACIAL PERIOD . , ; : . 802-331
CHAPTER X.

THe Date oF THE GLACIAL PERIOD . ; : : . 802-364

APPENDIX ON THE TERTIARY MAN : : ; : . 369-374

INDEX . > : 4 x : : : ; ; . 370-3885

List OF ILLUSTRATIONS:

FIG.
1. Zermatt Glacier
2. Formation of veined crruehire :
3, 4. Formation of marginal fissures and veins
5. Fissures and seracs .
6. Section across glacial valley, showing ale lateral moraines .
7. Mont Blane glacier region
8. Svartisen Glacier .
9. Floating berg
10. Iceberg in the Matatcuie cern
11. Map of southeastern Alaska .
12. Map of Glacier Bay, Alaska .
13. Front of Muir Glacier . : :
14. Map of glaciers in the St. Elias Alps .
15. Map of Greenland .
16. Diagram showing the character of Sal motion
17. Line of most rapid glacial motion :
18. Diagram showing retardation of the Botton ofa Pace
19. Bed-rock scored with glacial marks
20. Scratched stone from the till of Boston
21. Typical section of till in Seattle, Wash.
22. Ideal section showing how the till overlies the stratified
rocks. :
23. Vessel Rock, a glacial boulder
24. Map of Rhone Glacier .
25. Conglomerate boulder found in Beans, Game ier
26. Mohegan Rock : :
27. Drumlins in Goffstown, N. H. :
_ 28. Map of drumlins in the vicinity of Boston .
29. Section of kame ; :
30. Map of kames in Andover, Mass, ; ‘
2

Xxx MAN AND THE GLACIAL PERIOD.

FIG.
. Longitudinal kames near Hingham, Mass. .
. Map showing the kames of Maine and southeastern New

Hampshire

. Western face of the Kettle Mannie near Horie Wi is,
. Section of the east-and-west glacial furrows on Kelly’s

Island

. Same as the preceding

}. Section of till near Germantown, on

. Moraines of Grape Creek, Col. :

. Map of North America in the Ice period

. Quartzite boulder on Mont Lachat

. Map showing glaciated areas in North ‘Awenien ane

Europe

. Maps showing lines of Tess Stowing tole ine tne sits

the plains of the Po.

. Section of the Cefn Cave

. Map showing moraine between Specton aa Hilembaranen
. Diagram-section near Cromer

. Section through the westerly chalk bluff ee Tsimin saat

Norfolk

. Section across Wales
. Section of cliff at Flamborough Heads §
. Enlarged section of the shelly sand and cdreounding As,

at B in preceding figure .

. Map showing the glaciated area of Barope :

. Map showing old channel and mouth of the Hudson .

. New York Harbor in preglacial times .

2. Section across the valley of the Cuyahoga River.

. Map of Mississippi River from Fort Snelling to Mines

apolis

. Map showing the effect of the Blacial acum at Gincimmats

. Map of Lake Erie-Ontario

. Map of Cuyahoga Lake ; A

. Section of the lake ridges near Sandusky: Ohio ; ;
. Map showing stages of recession of the ice in Minnesota .
. Glacial terrace on Raccoon Creek, in Ohio .

. Ideal section across a river-bed in drift region

. Map of Lakes Bonneville and Lahontan

62.
. Map showing glacial terraces on the Delaware ir Sehaagle

Parallel roads of Glen Roy .

kill Rivers F ; F : . 5 ‘ 3 :

PAGE

79

81
99

102
105
108
123
Mea
128

130

154
148
156
166

162
172
176

177
184
195
197
200

209
213
219
221
223
225
227
229
234
239

243

——

LIST OF ILLUSTRATIONS.

. Paleolith found by Abbott in New Jersey . :

. Section across the Delaware River at Trenton, N. J. .

. Section of the Trenton gravel

. Face view of argillite implement found de De Cc . IN

bott in 1876

. Argillite implement found by Dr. C, Oeuabars Maron

1879.

. Chipped pebble of black chene found by Dr. C, L. Metz,

October, 1885

. Map showing glaciated area in Ohio : ;
. Paleoliths from Newcomerstown and Amiens (ace view) .
. Hdge view of the preceding .

. Section across the Mississippi Valley a ibaille Falls, Minnis

. Quartz implement found by Miss F. E. Babbitt, 1878, at

Little Falls, Minn.

. Argillite implement found by H. T. Cresson, 1887
16. General view of Baltimore and Ohio Railroad cut, near

Claymont, Del.

. Section across valley of the Serie

. Mouth of Kent’s Hole .

. Engis skull (reduced)

. Comparison of forms of skulls

. Skull of the Man of Spy

. Tooth of Machairodus neogzeus

. Perfect tooth of an Elephas

. Skull of Hyena spelexa .

. Celebrated skeleton of marie in ey Dererburs Mu-

seum .

. Molar tooth of aioth

. Tooth of Mastodon Americanus .

8. Skeleton of Mastodon Americanus

. Skeleton of Rhinoceros tichorhinus

. Skull of ecave-bear

. Skeleton of the Irish elk

2. Musk-sheep .

. Reindeer

. Section across Table Maen enn: (valine County, Gal
. Calaveras skull

. Three views of Nampa image, drawn le eal

. Map showing Pocatello, Nampa, and the valley of Sn: ae

River 5 -

HH OO

w WLW 09

(0 OO ONO ONO SI@ 6)
y=

mW
Dm DPD
Omri 2

XXX1l MAN AND THE GLACIAL PERIOD.

FIG.

98.
99.
100.
101.
102.

103.
104.
105.
106.

107.
108.

Section across the channel of the Stanislaus River

Diagram showing effect of precession . .

Map showing course of currents in the Aden: Oceana

Map showing how the land clusters about the north pole.

Diagram showing oscillations of land-surface and ice-
surface during the Glacial epoch

Diagram of eccentricity and precession

Map of the Niagara River below the Falls

Section of strata along the Niagara Gorge.

Map showing the recession of the Horseshoe Falls since
1842

Section of kettle- Hole near Pomp" S Bond Andy eG Mase

Flint-flakes collected by Abbé Bourgeois .

MAPS.

TO FACE PAGE
Contour and glacial map of the British Isles . Frontispiece.
Map showing the glacial geology of the United States
Map of glacial movements in France and Switzerland

66
182

MAN AND THE GLACIAL PERIOD.

CEA EEiiy

INTRODUCTORY.

THAT glaciers now exist in the Alps, in the Scandi-
navian range, in Iceland, in the Himalayas, in New Zea-
land, in Patagonia, and in the mountains of Washington,
British Columbia, and southeastern Alaska, and that a
vast ice-sheet envelops Greenland and the Antarctic Con-
tinent, are statements which can be verified by any one
who will take the trouble to visit those regions. That, at
a comparatively recent date, these glaciers extended far
' beyond their present limits, and that others existed upon
the highlands of Scotland and British America, and at
one time covered a large part of the British Isles, the
whole of British America, and a considerable area in the
northern part of the United States, are inferences drawn
from phenomena which are open to every one’s observa-
tions. That man was in existence and occupied both Eu-
rope and America during this great expansion of the
northern glaciers is proved by evidence which is now be-
yond dispute. It is the object of the present vclume to
make a concise presentation of the facts which have been
rapidly accumulating during the past few years relating
to the Glacial period and to its connection with human
history.

Before speaking of the number and present extent of
existing glaciers, it will be profitable, however, to devote a
little attention to the definition of terms.

9 MAN AND THE GULACIAL PERIOD.

A glacier is a mass of ice so situated and of such size as
to have motion in itself. The conditions determining the

Fie. 1.—Zermatt Glacier (Agassiz).

character and rate of this motion will come up for state-
ment and discussion later. It is sufficient here to say that
ice has a capacity of movement similar to that possessed
by such plastic substances as cold molasses, wax, tar, or
cooling lava.

The limit of a glacier’s motion is determined by the
forces which fix the point at which its final melting takes
place. his will therefore depend upon both the warmth
of the weather and upon the amount of ice. If the ice
is abundant, it will move farther into the region of warm
temperature than it will if it is limited in supply.

Upon ascending a glacier far enough, one reaches a

—

INTRODUCTORY. 3

comparatively motionless part corresponding to the lake
out of which a river often flows. Technically this is
called the névé. }

Glacial ice is formed from snow where the annual fail
is in excess of the melting power of the sun at that point.
Through the influence of pressure, such as a boy applies
to a snow-ball (but which in the névé field arises from the
weight of the accumulating mass), the lower strata of the
névé are gradually transformed into ice. This process. is
also assisted by the moisture which percolates through the
snowy mass, and which is furnished both by the melting
of the surface snow and by occasional rains.

The division between the névé and the glacier proper is
not always easily determined. The beginnings of the glacial
movement—that is, of the movement of the ice-stream
. flowing out of the névé field—are somewhat like the begin-
nings of the movement of the water from a great lake
into its outlet. The névé is the reservoir from which the
glacier gets both its supply of ice and the impulse which
gives it its first movement. ‘There can not be a glacier
without a névé field, as there can not be a river without a
drainage basin. But there may 3
be a névé field without a glacier—
that is, a basin may be partially
filled with snow which never melts
completely away, while the equi-
librium. of forces is such that the
ice barely. reaches to the outlet
from which the tongue-like pro-
jection (to which the name glacier
would be applied) fails to emerge Fie. 2.—Illustrates the forma-

tion of veined structure by
Omlye because OLetine lack Oi mates). = mesure ay thegunetionjor

two branches.
rial.
A glacier is characterised by both veins and fissures.
The veins give it a banded or stratified appearance, blue
alternating with lighter-coloured portions of ice. As these

4. MAN AND THE GLACIAL PERIOD.

bands are not arranged with any apparent uniformity in
the glacier, their explanation has given rise to much dis-
cussion. Sometimes the veins are horizontal, sometimes
vertical, and at other times at an angle with the line of
motion. On close investigation, however, it is found that
the veins are always at right angles to the line of greatest
pressure. This leads to the conclusion that pressure is
the cause of the banded structure. The blue strata in the
ice are those from which the particles of air have been
expelled by pressure ;
the hghter portions are
those in which the par-
ticles are less thorough-
ly compacted. Snow is
but pulverized ice, and
,; differs in colour from
ee tas ide eee pear the compact mass for
Figs. 3, 4.—Illustrate the formation of mar- the same reason that al-
ginal fissures and veins. :

most all rocks and min-

erals change their colour when ground into a powder.

The fissures, which, when of large size, are called
crevasses, are formed in those portions of a glacier where,
from some cause, the ice is subjected to slight tension. This
occurs especially where, through irregularities in the bot-
tom, the slope of the descent is increased. The
ice, then, instead of moving in a continuous

stream at the top, cracks open
e along the line of tension, and

ae wedge-shaped
lp ge-shap
HG EM Ma

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fissures are
formed ex-
Fie. 5.—c, c, show fissures and seracs where the glacier tending from
moves down the steeper portion of its incline; s, s,
show the vertical structure produced by pressure on the top down
the gentler slopes.
to a greater
or less distance, according to the degree of tension. Usu-

ally, however, the ice remains continuous in the lower

INTRODUCTORY. 5

strata, and when the slope is diminished the pressure re-
unites the faces of the fissure, and the surface becomes
again comparatively smooth. Where there are extensive
-areas of tension, the surface of the ice sometimes becomes
exceedingly broken, presenting a tangled mass of towers,
domes, and pinnacles of ice called seracs.

Like running water, moving ice is a powerful agent in
transporting rocks and earthy débris of all grades of
fineness; but, owing to the different consistencies of ice
and water, there are great differences in the mode and
result of transportation by them. While water can hold
in suspension only the very finest material, ice can bear
upon its surface

rocks of the great- 4 eee es Te the
est magnitude, and :
ean roll or shove “lp Ste ee ane see
along under it ON

boulders and peb- : ~ = =
bles which would ”», ho

be unaffected eX- fe. 6.—Section across Glacial Valley, showing old
cept by torrential Lateral Moraines.

currents of water. We find, therefore, a great amount of
earthy material of all sizes upon the top of a glacier, which
has reached it very much as débris reaches the bed of a
river, namely, by falling down upon it from overhanging
cliffs, or by land-slides of greater or less extent. Such
material coming into a river would either disappear be-
neath its surface, or would form a line of débris along the
banks; in both cases awaiting the gradual erosion and
transportation which running water is able to effect. But,
in case of a glacier, the material rests upon the surface of
the ice, and at once begins to partake of its motion, while
successive accessions of material keep up the supply at any
one point, so as to form a train of boulders and other
débris, extending below the point as far as the glacial
motion continues.

6 MAN AND THE GLACIAL PERIOD.

Such a line of débris is called a moraine. When it
forms along the edge of the ice, it is called a lateral
moraine. It is easy to see that, where glaciers come out
from two valleys which are tributary to a larger valley,
their inner sides must coalesce below the separating prom-
ontory, and the two lateral moraines will become united
and will move onward in the middle of the surface of the
glacier. Such lines of débris are called medial moraines.
These are characteristic of all extensive glaciers formed by
the union of tributaries. There is no limit to the number
of medial moraines, except in the number of tributaries.

A medial moraine, when of sufficient thickness, pro-
tects the ice underneath it from melting; so that the
moraine will often appear to be much larger than-it really
is: what seems to be a ridge of earthy material being in
reality a long ridge of ice, thinly covered with earthy dédris,
sliding down the slanting sides as the ice slowly wastes
away Large blocks of stone in the same manner protect
the ice from melting underneath, and are found standing
on pedestals of ice, often several feet in height. An in-
teresting feature of these blocks is that, when the pedestal
fails, the block uniformly falls towards the sun, since that
is the side on which the melting has proceeded most
rapidly.

If the meteorological forces are so balanced that the
foot of a glacier remains at the same place for any great
length of time, there must be a great accumulation of
earthy débris at the stationary point, since the motion of
the ice is constantly bearing its lines of lateral and medial
moraine downwards to be deposited, year by year, at the
melting line along the front.

Such accumulations are called ferminal moraines, and
the process of their formation may be seen at the foot of
almost any large glacier. The pile of material thus con-
fusedly heaped up in front of some of the larger glaciers
of the world is enormous.

ne

INTRODUCTORY. 7

The melting away of the lower part of a glacier gives
rise also to several other characteristic phenomena. Where
the foot of a glacier chances to be on comparatively level
land, the terminal moraine often covers a great extent of
ice, and protects it from melting for an indefinite period
of time. When the ice finally melts away and removes the
support from the overlying morainic dédris, this settles
down in a very irregular manner, leaving enclosed depres-
sions to which there is no natural outlet. ‘These depres-
sions, from their resemblance to a familar domestic uten-
sil, are technically known as kettle-holes. The terminal
moraines of ancient glaciers may often be traced by the
relative abundance of these kettle-holes.

The streams of water arising both from the rainfall
and from the melting of the ice also produce a peculiar
effect about the foot of an extensive glacier. Sometimes
these streams cut long, open channels near the end of the
glacier, and sweep into it vast quantities of morainic mate-
rial, which is pushed along by the torrential current, and,
after being abraded, rolled, and sorted, is deposited in a
delta about its mouth, or left stranded in long lines be-
tween the ice-walls which have determined its course. At
other times the stream has disappeared far back in the
glacier, and plunged into a crevasse (technically called a
moulin), whence it flows onwards as a subglacial stream.
But in this case the deposits might closely resemble those
of the previous description. In both cases, when the ice
has finally melted away, peculiar ridge-like deposits of
sorted material remain, to mark the temporary line of
drainage. ‘These exist abundantly in most regions which
have been covered with glacial ice, and are referred to in
Scotland as kames, in Ireland as eskers, and in Sweden as
osars. In this volume we shall call them ames, and the
deltas spread out in front of them will be referred to as
kame-plains.

With this preliminary description of glacial phenome-

8 MAN AND THE GLACIAL PERIOD.

na, we will proceed to give, first, a brief enumeration and
description of the ice-fields which are still existing in the
world; second, the evidences of the former existence of
far more extensive ice-fields; and, third, the relation of
the Glacial period to some of the vicissitudes which have
attended the life of man in the world.

The geological period of which we shall treat is vari-
ously designated by different writers. By some it is simply
called the “ post-Tertiary,” or “ Quaternary ”; by others
the term “ post-Pliocene ” is used, to indicate more sharply
its distinction from the latter portion of the Tertiary
period; by others this nicety of distinction is expressed
by the term “ Pleistocene.” But, since the whole epoch
was peculiarly characterised by the presence of glaciers,
which have not even yet wholly disappeared, we may
properly refer to it altogether under the descriptive name
of “ Glacial” period.

CitA PE UE.
EXISTING GLACIERS.

In Europe.—Our specific account of existing glaciers
naturally begins with those of the Alps, where Hugi,
Charpentier, Agassiz, Forbes, and Guyot, before the mid-
dle of this century, first brought clearly to light the reality
and nature of glacial motion.

According to Professor Heim, of Ziirich, the total area
covered by the glaciers and ice-fields of the Alps is up-
wards of three thousand square kilometres (about eleven
hundred square miles). The Swiss Alps alone contain
nearly two-thirds of this area. Professor Heim enumer-
ates 1,155 distinct glaciers in the region. Of these, 144
are in France, 78 in Italy, 471 in Switzerland, and 462 in
Austria.

Desor describes fourteen principal glacial districts in
the Alps, the westernmost of which is that of Mont Pel-
voux, in Dauphiny, and the easternmost that in the vicin-
ity of the Gross Glockner, in Carinthia. The most im-
portant of the Alpine systems are those which are grouped
around Mont Blane, Monte Rosa, and the Finsteraarhorn,
the two former peaks being upwards of fifteen thousand
feet in height, and the latter upwards of fourteen thou-
sand. The area covered by glaciers and snow-fields in the
Bernese Oberland, of which Finsteraarhorn is the culmi-
nating point, is about three hundred and fifty square kilo-
metres (a hundred square miles), and contains the Aletsch
Glacier, which is the longest in Europe, extending twenty-
one kilometres (about fourteen miles) from the névé-field

10 MAN AND THE GLACIAL PERIOD.

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See ev

EXISTING GLACIERS. te

to its foot. The Mer de Glace, which descends from Mont
Blanc to the valley of Chamounix, has a length of about
eight miles below the névé-field. In all, there are esti-
mated to be twenty-four glaciers in the Alps which are
upwards of four miles long, and six which are upwards of
eight miles in length. The principal of these are the Mer
de Glace, of Chamounix, on Mont Blanc; the Gorner
Glacier, near Zermatt, on Monte Rosa; the lower glacier
of the Aar, in the Bernese Oberland; and the Aletsch
Glacier and Glacier of the Rhéne, in Vallais; and the
Pasterzen, in Carinthia.

These glaciers adjust themselves to the width of the
valleys down which they flow, in some places being a mile
or more in width, and at others contracting into much
narrower compass. ‘The greatest depth which Agassiz
was able directly to measure in the Aar Glacier was two
hundred and sixty metres (five hundred and twenty-eight
feet), but at another point the depth was estimated by
him to be four hundred and sixty metres (or fifteen hun-
dred and eighty-four feet).

The glaciers of the Alps are mostly confined to the
northern side and to the higher portions of the mountain-
chain, none of them descending below the level of four
thousand feet, and all of them varying shghtly in extent,
from year to year, according as there are changes in the
temperature and in the amount of snow-fall.

The Pyrenees, also, still maintain a glacial system, but
it is of insignificant importance. ‘This is partly because
the altitude is much less than that of the Alps, the cul-
minating point being scarcely more than eleven thousand
feet in height. Doubtless, also, it is partly due to the
narrowness of the range, which does not provide gathering-
places for the snow sufficiently extensive to produce large
glaciers. ‘The snow-fall also is less upon the Pyrenees
than upon the Alps. As a consequence of all these con-
ditions, the glaciers of the Pyrenees are scarcely more

12 MAN AND THE GLACIAL PERIOD.

than stationary névé-fields lingermg upon the north side
of the range. The largest of these is near Bagnéres de
Luchon, and sends down a short, river-like glacier.

In Scandinavia the height of the mountains is also
much less than that of the Alps, but the moister climate
and the more northern latitude favours the growth of
glaciers at a much lower level North of the sixty-second
degree of latitude, the plateaus over five thousand feet
above the sea pretty generally are gathering-places for
glaciers. From the Justedal a snow-field, covering five
hundred and eighty square miles, in latitude 62°, twenty-
-four glaciers push outwards towards the German Sea, the
largest of which is five miles long and three-quarters of a
mile wide. The Fondalen snow-field, between latitudes
66° and 67°, covers an area about equal to that of the
Justedal; but, on account of its more northern position,
its glaciers descend through the valleys quite to the ocean-
level. The Folgofon snow-field is still farther south, but,
though occupying an area of only one hundred square
miles, it sends down as many as three glaciers to the sea-
level. The total area of the Scandinavian snow-fields is
about five thousand square miles.

In Sweden Dr. Svenonius estimates that there are,
between latitudes 67° and 684°, twenty distinct groups of
glaciers, covering an area of four hundred square kilo-
metres (one hundred and forty-four square miles), and he
numbers upwards of one hundred distinct glaciers of small
size.

As is to be expected, the large islands in the Polar
Sea north of Europe and Asia are, to a great extent,
covered with névé-fields, and numerous glaciers push out
from them to the sea in all directions, discharging their
surplus ice as bergs, which float away and cumber the
waters with their presence in many distant places.

The island of Spitzbergen, in latitude 76° to 81°, 1s
favourably situated for the production of glaciers, by

=

EXISTING GLACIERS. 13

reason both of its high northern latitude, and of its rela-
tion to the Gulf Stream, which conveys around to it an
excessive amount of moisture, thus ensuring an excep-

—___—_-—_-_----

Fig. 8.—The Svartisen Glacier on the west coast of Norway, just within the Arc-
tic circle, at the head of a fiord ten miles from the ocean. The foot of the
Glacier is one mile wide, and a quarter of a mile back from the water. Ter-
minal moraine in front. (Photographed by Dr. L. C. Warner.)

tionally large snow-fall over the island. The mountainous
character of the island also favours the concentration of
the ice-movement into glaciers of vast size and power.
Still, even here, much of the land is free from snow and
ice in summer. But upon the northern portion of the
island there is an extensive table-land, upwards of two
thousand feet above the sea, over which the ice-field is
continuous. Four great glaciers here descend to tide-wa-
ter in Magdalena Bay. The largest of these presents at the
front a wall of ice seven thousand feet across and three
hundred feet high; but, as the depth of the water is not

‘uh MAN AND THE GLACIAL PERIOD.

great, few icebergs of large size break off and float away
from it.

Nova Zembla, though not in quite so high latitude,
has a lower mean temperature upon the coasts than Spitz-
bergen. Owing to the absence of high lands and moun-
tains, however, it is not covered with perpetual snow,
much less with glacial ice, but its level portions are
“carpeted with grasses and flowers,” and sustain exten-
sive forests of stunted trees.

Franz-Josef Land, to the north of Nova Zembla, both
contains high mountains and supports glaciers of great
size. Mr. Payer conducted a sledge party into this land
in 1874, and reported that a precipitous wall of glacial
ice, “of more than a hundred feet in height, formed the
usual edge of the coast.” But the motion of the ice is
very slow, and the ice coarse-grained in structure, and it
bears a small amount only of morainic material. So low
is here the line of perpetual snow, that the smaller islands
“are covered with caps of ice, so that a cross-section
would exhibit a regular flat segment of ice.” It is in-
teresting to note, also, that “many ice-streams, descend-
ing from the high névé plateau, spread themselves out
over the mountain-slopes,” and are not, as in the Alps,
confined to definite valleys.

Iceland seems to have been properly named, since a
single one of the snow-fields—that of Vatnajokull, with
an extreme elevation of only six thousand feet—is esti-
mated by Helland to cover one hundred and fifty Nor-
wegian square miles (about seven thousand English square
miles), while five other ice-fields (the Langjokull, the
Hofsjokill, the Myrdalsjoktll, the Drangajokiill, and the
Glamujokill) have a combined area of ninety-two Nor-
wegian or about four thousand five hundred English
square miles. The glaciers are supposed by Whitney to
have been rapidly advancing for some time past.

In Asia.—Notwithstanding its lofty mountains and its

EXISTING GLACIERS. 15

great extent of territory lying in high latitudes, glaciers
are for two reasons relatively infrequent: 1. The land in
the more northern latitudes is low. 2. The dryness of the
atmosphere in the interior of the continent is such that it
unduly limits the snow-fall. Long before they reach the
central plateau of Asia, the currents of air which sweep
over the continent from the Indian Ocean have parted
with their burdens of moisture, having left them in a
snowy mantle upon the southern flanks of the Himalayas.
As a result, we have the extensive deserts of the interior,
where, on account of the clear atmosphere, there is not
snow enough to resist continuously the intense activity of
the unobstructed rays of the sun.

In spite of their high latitude and considerable eleva-
tion above the sea-level, glaciers are absent from the Ural
Mountains, for the range is too narrow to afford névé-
fields of sufficient size to produce glaciers of large ex-
tent.

The Caucasus Mountains present more favourable con-
ditions, and for a distance of one hundred and twenty
miles near their central portion have an average height of
12,000 feet, with individual peaks rising to a height of
16,000 feet or more; but, owing to their low latitude, the
line of perpetual snow scarcely reaches down to the 11,-
000-foot level. So great are the snow-fields, however,
above this height that many glaciers push their way down
through the narrow mountain-gorges as far as the 6,000-
foot level.

The Himalaya Mountains present many favourable con-
ditions for the development of glaciers of large size. The
range is of great extent and height, thus affording ample
gathering-places for the snows, while the relation of the
mountains to the moisture-laden winds from the Indian
Ocean is such that they enjoy the first harvest of the clouds
where the interior of Asia gets only the gleanings. As is
to be expected, therefore, all the great rivers which course

16 MAN AND THE GLACIAL PERIOD.

through the plains of Hindustan have their rise in large
glaciers far up towards the summits of the northern
mountains. The Indus and the Ganges are both glacial
streams in their origin, as are their larger tributary
branches—the Basha, the Shigar, and the Sutlej. Many
of the glaciers in the higher levels of the Himalaya
Mountains where these streams rise have a length of
from twenty-five to forty miles, and some of them are
as much as a mile and a half in width and extend for
a long distance, with an inclination as small as one de-
gree and a half or one hundred and thirty-eight feet to a
mile.

In the Mustagh range of the western Himalayas there
are two adjoining glaciers whose united length is sixty-
five miles, and another not far away which is twenty-one
miles long and from one to two miles wide in its upper
portion. Its lower portion terminates at an altitude of
16,000 feet above tide, where it is three miles wide and
two hundred and fifty feet thick.

Oceanica.— Passing eastward to the islands of the Pa-
cific Ocean, New Zealand is the only one capable of sup-
porting glaciers. ‘Their existence on this island seems
the more remarkable because of its low latitude (42° to
45°); but a grand range of mountains rises abruptly from
the water on the western coast of the southern island,
culminating in Mount Cook, 13,000 feet above the sea,
and extending for a distance of about one hundred miles.
The extent and height of this chain, coupled with the
moisture of the winds, which sweep without obstruction
over so many leagues of the tropical Pacific, are specially
favourable to the production of ice-fields of great extent.
Consequently we find glaciers in abundance, some of
which are not inferior in extent to the larger ones of
the Alps. The Tasman Glacier, described by Haas, is ten
miles long and nearly two miles broad at its termination,
“the lower portion for a distance of three miles being

EXISTING GLACIERS. 17

covered with morainic detritus.” The Mueller Glacier is
about seven miles long and one mile broad in its lower
portion.

South America.—In America, existing glaciers are
chiefly confined to three principal centres, namely, to
the Andes, south of the equator; to the Cordilleras, north
of central California; and to Greenland.

In South America, however, the high mountains of
Ecuador sustain a few glaciers above the twelve-thousand-
foot level. The largest of these are upon the eastern slope
of the mountains, giving rise to some of the branches of
the Amazon—indeed, on the flanks of Cotopaxi, Chimbo-
razo, and Illinissa there are some glaciers in close proximity
to the equator which are fairly comparable in size to those
of the Alps.

In Chili, at about latitude 35°, glaciers begin to ap-
pear at lower levels, descending beyond the six-thou-
sand-foot line, while south of this both the increasing
moisture of the winds and the decreasing average tem-
perature favour the increase of ice-fields and glaciers. Con-
sequently, as Darwin long ago observed, the line of per-
petual snow here descends to an increasingly lower level,
and glaciers extend down farther and farther towards the
sea, until, in Tierra del Fuego, at about latitude 45°, they
begin to discharge their frozen contents directly into the
tidal inlets. Darwin’s party surveyed a glacier entering
the Gulf of Penas in latitude 46° 50’, which was fifteen
miles long, and, in one part, seven broad. At Hyre’s
Sound, also, in about latitude 48°, they found immense
glaciers coming down to the sea and discharging icebergs
of great size, one of which, as they encountered it floating
outwards, was estimated to be “at least one hundred and
sixty-eight feet in total height.”

In Tierra del Fuego, where the mountains are only
from three thousand to four thousand feet in height and
in latitude less than 55°, Darwin reports that “ every val-

18 MAN AND THE GLACIAL PERIOD.

ley is filled with streams of ice descending to the sea-
coast,” and that the inlets penetrated by his party pre-
sented miniature likenesses of the polar sea.

Antarctic Continent.—Of the so-called Antarctic Con-
tinent little is known; but icebergs of great size are fre-
quently encountered up to 58° south latitude, in the direc-
tion of Cape Horn, and as far as latitude 33° in the di-
rection of Cape of Good Hope. Nearly all that is known
about this continent was discovered by Sir J. C. Ross

Fie. 9.—Floating berg, showing the proportions above and under the water.
About seven feet under water to one above.

during the period extending from 1839 to 1843, when,
between the parallels of 70° and 78° south latitude, he
encountered in his explorations a precipitous mountain
coast, rising from seven thousand to ten thousand feet
above tide. Through the valleys intervening between the
mountain-ranges huge glaciers descended, and “ projected
in many places several miles into the sea and terminated.

EXISTING GLACIERS. 19

in lofty, perpendicular cliffs. In a few places the rocks
broke through their icy covering, by which alone we could
be assured that land formed the nucleus of this, to appear-
ance, enormous iceberg.” *

Again, speaking of the region in the vicinity of the
lofty voleanoes Terror and Krebus, between ten thousand
and twelve thousand feet high, the same navigator says:

“We perceived a low, white line extending from its
extreme eastern point, as far as the eye could discern,
to the eastward. It presented an extraordinary appear-
ance, gradually increasing in height as we got nearer to
it, and proving at length to be a perpendicular cliff of
ice, between one hundred and fifty and two hundred feet
above the level of the sea, perfectly flat and level at the
top, and without any fissures or promontories on its even,
seaward face. What was beyond it we could not imagine;
for, being much higher than our mast-head, we could not
see anything except the summit of a lofty range of moun-
tains extending to the southward as far as the seventy-
ninth degree of latitude. These mountains, being the
southernmost land hitherto discovered, I felt great satis-
faction in naming after Sir Edward Parry. . . . Whether
Parry Mountains again take an easterly trending and
form the base to which this extraordinary mass of ice is
attached, must be left for future navigators to determine.
If there be land to the southward it must be very remote,
or of much less elevation than any other part of the coast
we have seen, or it would have appeared above the barrier.”

This ice-cliff or barrier was followed by Captain Ross
as far as 198° west longitude, and found to preserve very
much the same character during the whole of that dis-
tance. On the lithographic view of this great ice-sheet
given in Ross’s work it is described as “ part of the South
Polar Barrier, one hundred and eighty feet above the sea-

* Quoted by Whitney in Climatic Changes, p. 314.

0) MAN AND THE GLACIAL PERIOD.

level, one thousand feet thick, and four hundred and fifty
miles in length.”

A similar vertical wall We ice was seen by D’Urville, off
the coast of Adelie Land. He thus describes it: “ Its ap-
pearance was astonishing. We perceived a cliff having a
uniform elevation of from one hundred to one hundred
and fifty feet, forming a long line extending off to the
west. . . . Thus for more than twelve hours we had fol-
lowed this wall of ice, and found its sides everywhere per-
fectly vertical and its summit horizontal. Not the small-
est irregularity, not the most inconsiderable elevation,
broke its uniformity for the twenty leagues of distante
which we followed it during the day, although we passed
it occasionally at a distance of only two or three miles, so
that we could make out with ease its smallest irregulari-

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Fie. 10.—Iceberg in the Antarctic Ocean.

ties. Some large pieces of ice were lying along the side
of this frozen coast; but, on the whole, there was open
sea in the offing.” *

North America.—In North America living glaciers

* Whitney’s Climatic Changes, pp. 315, 316.

EXISTING GLACIERS, 21

begin to appear in the Sierra Nevada Mountains, in the
vicinity of the Yosemite Park, in central California. Here
the conditions necessary for the production of glaciers are
favourable, namely, a high altitude, snow-fields of consid-
erable extent, and unobstructed exposure to the moisture-
laden currents of air from the Pacific Ocean. Sixteen
glaciers of small size have been noted among the summits
to the east of the Yosemite; but none of them descend
much below the eleven-thousand-foot line, and none of
them are over a mile in length. Indeed, they are so small,
and their motion is so slight, that it is a question whether
or not they are to be classed with true glaciers.

Owing to the comparatively low elevation of the Sierra
Nevada north of Tuolumne County, California, no other
living glaciers are found until reaching Mount Shasta, in
the extreme northern part of the State. This is a volcanic
peak, rising fourteen thousand five hundred feet above
the sea, and having no peaks within forty miles of it as
high as ten thousand feet; yet so abundant is the snow-
fall that as many as five glaciers are found upon its north-
ern side, some of them being as much as three miles long
and extending as low down as the eight-thousand-foot
level. Upon the southern side glaciers are so completely
absent that Professor Whitney ascended the mountain
and remained in perfect ignorance of its glacial system.
In 1870 Mr. Clarence King first discovered and described
them on the northern side.

North of California glaciers characterise the Cascade
Range in increasing numbers all the way to the Alaskan
Peninsula. They are to be found upon Diamond Peak,
the Three Sisters, Mount Jefferson, and Mount Hood, in
Oregon, and appear in still larger proportions upon the
flanks of Mount Rainier (or Tacoma) and Mount Baker,
in the State of Washington. The glacier at the head of
the White River Valley is upon the north side of Rainier,
and is the largest one upon that mountain, reaching

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Fie. 11.—Map of Southeastern Alaska. The arrow-points mark glaciers.

EXISTING GLACIERS. 23

down to within five thousand feet of the sea-level, and
being ten miles or more in length. All the streams which
descend the valleys upon this mountain are charged with
the milky-coloured water which betrays their glacial origin.

In British Columbia, Glacier Station, upon the Cana-
dian Pacific Railroad, in the Selkirk Mountains, is within
half a mile of the handsome [Illicilliwaet Glacier, while
others of larger size are found at no great distance. The
interior farther north is unexplored to so great an extent
that little can be definitely said concerning its glacial phe-
nomena. The coast of British Columbia is penetrated by
numerous fiords, each of which receives the drainage of
a decaying glacier; but none are in sight of the tourist-
steamers which thread their way through the intricate
network of channels characterising this coast, until the
Alaskan boundary is crossed and the mouth of the Stick-
een River is passed.

A few miles up from the mouth of the Stickeen, how-
_ ever, glaciers of large size come down to the vicinity of
the river, both from the north and from the south, and
the attention of tourists is always attracted by the abun-
dant glacial sediment borne into the tide-water by the river
itself and discolouring the surface for a long distance be-
yond the outlet. Northward from this point the tourist
is rarely out of sight of ice-fields. The Auk and Patter-
son Glaciers are the first to come into view, but they do
not descend to the water-level. On nearing Holcomb
Bay, however, small icebergs begin to appear, heralding
the first of the glaciers which descend beyond the water’s
edge. Taku Inlet, a little farther north, presents glaciers
of great size coming down to the sea-level, while the whole
length of Lynn Canal, from Juneau to Chilkat, a distance
of eighty miles, is dotted on both sides by conspicuous
glaciers and ice-fields.

The Davidson Glacier, near the head of the canal, is
one of the most interesting for purposes of study. It

24 MAN AND THE GLACIAL PERIOD.

comes down from an unknown distance in the western in-
terior, bearing two marked medial moraines upon its sur-
face. On nearing tide-level, the valley through which
it flows is about three-quarters of a mile in width; but,
after emerging from the confinement of the valley, the
ice spreads out over a fan-shaped area until the width of
its front is nearly three miles. The supply of ice not be-
ing sufficient to push the front of the glacier into deep
water, equilibrium between the forces of heat and cold is
established near the water’s edge. Here, as from year to
year the ice melts and deposits its burdens of earthy dédris,
it has piled up a terminal moraine which rises from two
hundred to three hundred feet in height, and is now coy-
ered with evergreen trees of considerable size. From
Chilkat, at the head of Lynn Canal, to the sources of the
Yukon River, the distance is only thirty-five miles, but
the intervening mountain-chain is several thousand feet in
height and bears numerous glaciers upon its seaward
side.

About forty miles west of Lynn Canal, and separated
from it by a range of mountains of moderate height, is
Glacier Bay, at the head of one of whose inlets is the
Muir Glacier, which forms the chief attraction for the
great number of tourists that now visit the coast of south-
eastern Alaska during the summer season. ‘This glacier
meets tide-water in latitude 58° 50’, and longitude 136° 40’
west of Greenwich. It received its name from Mr. John
Muir, who, in company with Rey. Mr. Young, made a
tour of the bay and discovered the glacier in 1879. It
was soon found that the bay could be safely navigated by
vessels of large size, and from that time on tourists in
increasing number have been attracted to the region.
Commodious steamers now regularly run close up to the
ice-front, and lie-to for several hours, so that the passen-
gers may witness the “calving” of icebergs, and may
climb upon the sides of the icy stream and look into its

EXISTING GLACIERS. 25

deep crevasses and out upon its corrugated and broken
surface.

The first persons who found it in their way to pay
more than a tourist’s visit to this interesting object were

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Fie. 12.—Map of Glacier Bay, Alaska, and its surroundings,
Arrow-points indicate glaciated area.

Rey. J. L. Patton, Mr. Prentiss Baldwin, and myself, who
spent the entire month of August, 1886, encamped at the

296 MAN AND THE GLACIAL PERIOD.

foot of the glacier, conducting such observations upon it
as weather and equipment permitted. From that time

Fie. 13.—Shows central part of the front of Muir Glacier one half mile distant.
Near the lower left hand corner the ice is seen one mile distant resting for
about one half mile on gravel which it had overrun. The ice is now retreat-
ing in the channel. (From photograph.)

till the summer of 1890 no one else stopped off from the
tourist steamers to bestow any special study upon it.
But during this latter season Mr. Muir returned to the
scene of his discovered wonder, and spent some weeks in
exploring the interior of the great ice-field. During the
same season, also, Professors H. F. Reid and H. Cushing,
with a well-equipped party of young men, spent two
months or more in the same field, conducting observa-
tions and experiments, of various kinds, relating to the
extent, the motion, and the general behaviour of the vast
mass of moving ice.

The main body of the Muir Glacier occupies a vast

EXISTING GLACIERS. Q7

amphitheatre, with diameters ranging from thirty to forty
miles, and covers an area of about one thousand square
miles. From one of the low mountains near its mouth I
could count twenty-six tributary glaciers which came to-
gether and became confluent in the main stream of ice,
Nine medial moraines marked the continued course of as
many main branches, which becoming united formed the
grand trunk of the glacier. Numerous rocky eminences
also projected above the surface of the ice, like islands in
the sea, corresponding to what are called “ nwnataks” in
Greenland. The force of the ice against the upper side
of these rocky prominences is such as to push it in great
masses above the surrounding level, after the analogy of
waves which dash themselves into foam against similar
obstructions. In front of the nunataks there is uni-
formly a depression, like the eddies which appear in the
current below obstacles in running water.

Over some portions of the surface of the glacier there
is a miniature river system, consisting of a main stream,
with numerous tributaries, but all flowing in channels of
deep blue ice. Before reaching the front of the glacier,
however, each one of these plunges down into a crevasse,
or moulin, to swell the larger current, which may be
heard rushing along in an impetuous course hundreds of
feet beneath, and far out of sight. The portion of the
glacier in which there is the most rapid motion is char-
acterised by innumerable crags and domes and pinnacles
of ice, projecting above the general level, whose bases are
separated by fissures, extending in many cases more than
a hundred feet below the general level. These irregu-
larities result from the combined effect of the differential
motion (as illustrated in the diagram on page 4), and
the influence of sunshine and warm air in irregularly
melting the unprotected masses. The description given
in our introductory chapter of medial moraines and ice-
pillars is amply illustrated everywhere upon the surface

98 MAN AND THE GLACIAL PERIOD.

of the Muir Glacier. I measured one block of stone
which was twenty feet square and about the same height,
standing on a pedestal of ice three or four feet high.

The mountains forming the periphery of this amphi-
theatre rise to a height of several thousand feet; Mount
Fairweather, upon the northwest, from whose flanks prob-
ably a portion of the ice comes, being, in fact, more than
fifteen thousand feet high. The mouth of the amphi-
theatre is three miles wide, in a line extending from
shoulder to shoulder of the low mountains which guard
it. The actual water-front where the ice meets tide-water
is one mile and a half.* Here the depth of the inlet is
so great that the front of the ice breaks off in icebergs of
large size, which float away to be dissolved at their leisure.
At the water’s edge the ice presents a perpendicular front
of from two hundred and fifty to four hundred feet in
height, and the depth of the water in the middle of the
inlet immediately in front of the ice is upwards of seven
hundred feet; thus giving a total height to the precipitous
front of a thousand feet.

The formation of icebergs can here be studied to
admirable advantage. During the month in which we
encamped in the vicinity the process was going on con-
tinuously. There was scarcely an interval of fifteen
minutes during the whole time in which the air was not
rent with the significant boom connected with the “ ealy-
ing” of a berg. Sometimes this was occasioned by the
separation of a comparatively small mass of ice from near
the top of the precipitous wall, which would fall into the
water below with a loud splash. At other times I have
seen a column of ice from top to bottom of the precipice
split off and fall over into the water, giving rise to great
waves, which would lash the shore with foam two miles
below.

* These are the measurements of Professor Reid. In my former
volume I have given the dimensions as somewhat smaller.

EXISTING GLACIERS. 29

This manner of the production of icebergs differs
from that which has been ordinarily represented in the
text-books, but it conforms to the law of glacial motion,
which we will describe a little later, namely, that the
upper strata of ice move faster than the lower. Hence
the tendency is constantly to push the upper strata for-
wards, so as to produce a perpendicular or even projecting
front, after the analogy of the formation of breakers on
the shelving shore of a large body of water.

Evidently, however, these masses of ice which break
off from above the water do not reach the whole distance
to the bottom of the glacier below the water; so that a
projecting foot of ice remains extending to an indefinite
distance underneath the surface. But at occasional in-
tervals, as the superincumbent masses of ice above the
surface fall off and relieve the strata below of their weight,
these submerged masses suddenly rise, often shooting up
considerably higher than they ultimately remain when
coming to rest. The bergs formed by this latter process
often bear much earthy material upon them, which is
carried away with the floating ice, to be deposited finally
wherever the melting chances to take place.

Numerous opportunities are furnished about the front
and foot of this vast glacier to observe the manner of the
formation of kames, kettle-holes, and various other irregu-
lar forms into which glacial débris is accustomed to ac-
cumulate. Over portions of the decaying foot of the
- glacier, which was deeply covered with morainic dédris,
the supporting ice is being gradually removed through the
influence of subglacial streams or of abandoned tunnels,
which permit the air to exert its melting power under-
neath. In some places where old mouwdins had existed, the
supporting ice is melting away, so that the superincumbent
mass of sand, gravel, and boulders is slowly sliding into a
common centre, like grain ina hopper. This must pro-
duce a conical hill, to remain, after the ice has all melted

30 MAN AND THE GLACIAL PERIOD.

away, a mute witness of the impressive and complicated
forces which have been so long in operation for its pro-
duction.

In other places I have witnessed the formation of a
long ridge of gravel by the gradual fallmg in of the roof
of a tunnel which had been occupied by a subglacial
stream, and over which there was deposited a great amount
of morainic material. As the roof gave way, this was
constantly falling to the bottom, where, being exempt
from further erosive agencies, it must remain as a gravel
ridge or kame.

In other places, still, there were vast masses of ice
covering many acres, and buried beneath a great depth of
morainic material which had been swept down upon it
while joined to the main glacier. In the retreat of the
ice, however, these masses had become isolated, and the
sand, gravel, and boulders were shding down the wasting
sides and forming long ridges of débris along the bottom,
which, upon the final melting of the ice, will be left as a
complicated network of ridges and knolls of gravel, en-
closing an equally complicated nest of kettle-holes.

Beyond Cross Sound the Pacific coast is bounded for
several hundred miles by the magnificent semicircle of
mountains known as the St. Ehas Alps, with Mount Cril-
lon at the south, having an elevation of nearly sixteen
thousand feet, and St. Elias in the centre, rising to a
greater height. Everywhere along this coast, as far as the
Alaskan Peninsula, vast glaciers come down from the
mountain-sides, and in many cases their precipitous fronts
form the shore-line for many miles at a time. Icy Bay,
just to the south of Mount St. Elias, is fitly named, on
account of the extent of the glaciers emptying into it and
the number of icebergs cumbering its waters.

In the summer of 1890 a party, under the lead of Mr.
I. C. Russell, of the United States Geological Survey,
made an unsuccessful attempt to scale the heights of

EXISTING GLACIERS. 21

Mount St. Elias; but the information brought back by
them concerning the glaciers of the region amply repaid

IRVINO S157

Aaa gens
Cook 12370 p

UBBARD 7103

LEGEND
Route of the N.Y. Times Expedition 1886______
» «= » Topham c 1888 ...-
» = » Nat.GeogSocy., 1290
Campsie imintietetiane - o

SCALE OF STATUTE MILES
4 o é 10 i2 44 16 +R 20

Fic. 14.—By the courtesy of the National Geographical Society.

them for their toil and expense, and consoled them for
the failure of their immediate object.

Leaving Yakutat Bay, and following the route indi-
cated upon the accompanying map, they travelled on gla-
cial ice almost the entire distance to the foot of Mount
St. Khas. The numerous glaciers coming down from the

- summit of the mountain-ridge become confluent nearer
the shore, and spread out over an area of about a thousand
square miles. This is fitly named the Malaspina Glacier,
after the Spanish explorer who discovered it in 1792.

It is not necessary to add further particulars concern-

32 MAN AND THE GLACIAL PERIOD.

ing the results of this expedition, since they are so similar
to those already detailed in connection with the Muir
Glacier. A feature, however, of special interest, pertains
to the glacial lakes which are held in place by the glacial
ice at an elevation of thousands of feet above the sea. One
of considerable size is indicated upon the map just south
of what was called Blossom Island, which, however, is not
an island, but simply a nwnatak, the ice here surrounding
a considerable area of fertile land, which is covered with
dense forests and beautified by a brilliant assemblage of
flowering plants. In other places considerable vegetation
was found upon the surface of moraines, which were prob-
ably still in motion with the underlying ice.

Greenland.—Vhe continental proportions of Green-
land, and the extent to which its area is covered by glacial
ice, make it by far the most important accessible field for
glacial observations. The total area of Greenland can not
be less than five hundred thousand square miles—equal in
extent to the portion of the United States east of the Mis-
sissippi and north of the Ohio. It is now pretty evident
that the whole of this area, except a narrow border about
the southern end, is covered by one continuous sheet of
moving ice, pressing outward on every side towards the
open water of the surrounding seas.

For a long time it was the belief of many that a large
region in the interior of Greenland was free from ice, and
was perhaps inhabited. It was in part to solve this prob-
lem that Baron Nordenskiéld set out upon his expedition
of 1883. Ascending the ice-sheet from Disco Bay, in
latitude 69°, he proceeded eastward for eighteen days
across a continuous ice-field. Rivers were flowing in
channels upon the surface like those cut on land in hori-
zontal strata of shale or sandstone, only that the pure deep
blue of the ice-walls was, by comparison, infinitely more
beautiful. These rivers were not, however, perfectly con-
tinuous. After flowing for a distance in channels on the

EXISTING GLACIERS.

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34 MAN AND THE GLACIAL PERIOD.

surface, they, one and all, plunged with deafening roar
into some yawning crevasse, to find their way to the sea
through subglacial channels. Numerous lakes with shores
of ice were also encountered.

“On bending down the ear to the ice,” says this ex-
plorer, “we could hear on every side a peculiar subter-
ranean hum, proceeding from rivers flowing within the
ice; and occasionally a loud, single report, like that of a
cannon, gave notice of the formation of a new glacier-
cleft. . . . In the afternoon we saw at some distance from
us a well-defined pillar of mist, which, when we approached
it, appeared to rise from a bottomless abyss, into which a
mighty glacier-river fell. ‘The vast; roaring water-mass
had bored for itself a vertical hole, probably down to the
rock, certainly more than two thousand feet beneath, on
which the glacier rested.” *

At the end of the eighteen days Nordenskiéld found
himself about a hundred and fifty miles from his starting-
point, and about five thousand feet above the sea. Here
the party rested, and sent two Eskimos forward on skidor
—a kind of long wooden skate, with which they could
move rapidly over the ice, notwithstanding the numerous
small, circular holes which everywhere pitted the surface.
These Eskimos were gone fifty-seven hours, having slept
only four hours of the period. It is estimated that they
made about a hundred and fifty miles, and attained an
altitude of six thousand feet. The ice is reported as rising
in distinct terraces, and as seemingly boundless beyond.
If this is the case, two hundred miles from Disco Bay,
there would seem little hope of finding in Greenland an
interior freed from ice. So we may pretty confidently
speak of that continental body of land as still enveloped
in an ice-sheet. Up to about latitude 75°, however, the
continent is fringed by a border of islands, over which

* Geological Magazine, vol. ix, pp. 393, 399.

SS He

EXISTING GLACIERS. 35

there is no continuous covering of ice. In south Green-
land the continuous ice-sheet is reached about thirty miles
back from the shore. }

A summary of the results of Greenland exploration
was given by Dr. Rink in 1886, from which it appears
that since 1876 one thousand miles of the coast-line have
been carefully explored by entering every fiord and at-
tempting to reach the inland ice. According to this au-
thority—

We are now able to demonstrate that a movement of
ice from the central regions of Greenland to the coast
continually goes on, and must be supposed to act upon
the ground over which it is pushed so as to detach and
transport fragments of it for such a distance. ... The
plainest idea of the ice-formation here in question is given
by comparing it with an inundation. . . . Only the mar-
ginal parts show irregularity ; towards the interior the sur-
face grows more and more level and passes into a plain
very slightly rising in the same direction. It has been
proved that, ascending its extreme verge, where it has
spread like a lava-stream over the lower ground in front
of it, the irregularities are chiefly met with up to a height
of 2,000 feet, but the distance from the margin in which
the height is reached varies much. While under 683°
north latitude it took twenty-four miles before this eleva-
tion was attained, in 724° the same height was arrived
at in half the distance. .. .

A general movement of the whole mass from the cen-
tral regions towards the sea is still continued, but it con-
centrates its force to comparatively few points in the most
extraordinary degree. ‘These points are represented by
the ice-fiords, through which the annual surplus ice is
carried off in the shape of bergs. . . . In Danish Green-
land are found five of the first, four of the second, and
eight of the third (or least productive) class, besides a
number of inlets which only receive insignificant frag-

36 MAN AND THE GLACIAL PERIOD.

ments. Direct measurements of the velocity have now
been applied on three first-rate and one second-rate fiords,
all situated between 69° and 71° north latitude. The
measurements have been repeated during the coldest and
the warmest season, and connected with surveying and
other investigations of the inlets and their environs. It
is now proved that the glacier branches which produce
the bergs proceed incessantly at a rate of thirty to fifty
feet per diem, this movement being not at all influenced
by the seasons. .. .

In the ice-fiord of Jakobshavn, which spreads its enor-
mous bergs over Disco Bay and probably far into the At-
lantic, the productive part of the glacier is 4,500 metres
(about 24 miles) broad. ‘The movement along its middle
line, which is quicker than on the sides nearer the shores,
can be rated at fifty feet per diem. The bulk of ice here
annually forced into the sea would, if taken on the shore,
make a mountain two miles long, two miles broad, and
1,000 feet high. The ice-fiord of Torsukatak receives
four or five branches of the glacier; the most productive
of them is about 9,000 metres broad (five miles), and
moves between sixteen and thirty-two feet per diem. The
large Karajak Glacier, about 7,000 metres (four miles)
broad, proceeds at a rate of from twenty-two to thirty-
eight feet per diem. Finally, a glacier branch dipping
into the fiord of Jtivdliarsuk, 5,800 metres broad (three
miles), moved between twenty-four and forty-six feet per
diem.”

The principal part of our information concerning the
glaciers of Greenland north of Melville Bay was obtained
by Drs. Kane and Hayes, in 1853 and 1854, while con-
ducting an expedition in search of Sir John Franklin and
his unfortunate crew. Dr. Hayes conducted another ex-

* See Transactions of the Edinburgh Geological Society for Feb-
ruary 18, 1886, vol. v, part 11, pp. 286-293.

—————

EXISTING GLACIERS. 37

pedition to the same desolate region in 1860, while other
explorers have to some extent supplemented their obser-
vations. The largest glacier which they saw enters the
sea between latitude 79° and 80°, where it presents a pre-
cipitous discharging front more than sixty miles in width
and hundreds of feet in perpendicular height.

Dr. Kane gives his first impressions of this grand gla-
cier in the following vivid description :

“T will not attempt to do better by florid description.
Men only rhapsodize about Niagara and the ocean. My
notes speak simply of the ‘long, ever-shining line of cliff
diminished to a well-pointed wedge in the perspective’;
and, again, of ‘ the face of glistening ice, sweeping in a
long curve from the low interior, the facets in front in-
tensely illuminated by the sun.’ But this line of cliff
rose in a solid, glassy wall three hundred feet above the
water-level, with an unknown, unfathomable depth below
it; and its curved face, sixty miles in length from Cape
Agassiz to Cape Forbes, vanished into unknown space at
not more than a single day’s railroad-travel from the pole.
The interior, with which it communicated and from
which it issued, was an unsurveyed mer de glace—an ice-
ocean to the eye, of boundless dimensions.

“Tt was in full sight—the mighty crystal bridge which
connects the two continents of America and Greenland.
I say continents, for Greenland, however insulated it may
ultimately prove to be, is in mass strictly continental. Its
least possible axis, measured from Cape Farewell to the
line of this glacier, in the neighbourhood of the eightieth
parallel, gives a length of more than 1,200 miles, not ma-
terially less than that of Australia from its northern to its
southern cape.

“Tmagine, now, the centre of such a continent, occu-
pied through nearly its whole extent by a deep, unbroken
sea of ice that gathers perennial increase from the water-
shed of vast snow-covered mountains and all the precipi-

38 MAN AND THE GLACIAL PERIOD.

tations of its atmosphere upon its own surface. Imagine
this, moving onwards lke a great glacial river, seeking
outlets at every fiord and valley, rolling icy cataracts into
the Atlantic and Greenland seas; and, having at last
reached the northern limit of the land that has -borne it
up, pouring out a mighty frozen torrent into unknown
arctic space !

“Tt is thus, and only thus, that we must form a just
conception of a phenomenon like this great glacier. I
had looked in my own mind for such an appearance,
should I ever be fortunate enough to reach the northern
coast of Greenland; but, now that it was before me, I
could hardly realize it. I had recognized, in my quiet
library at home, the beautiful analogies which Forbes and |
Studer have developed between the glacier and the river.
But I could not comprehend at first this complete substi-
tution of ice for water.

“Tt was slowly that the conviction dawned on me that
I was looking upon the counterpart of the great river-
system of Arctic Asia and America. Yet here were no
water-feeders from the south. Every particle of moisture
had its origin within the polar circle and had been con-
verted into ice. 'There were no vast alluvions, no forest
or animal traces borne down by liquid torrents. Here
was a plastic, moving, semi-solid mass, obliterating life,
swallowing rocks and islands, and ploughing its way with
irresistible march through the crust of an investing sea.” *

Much less is known concerning the eastern coast of
Greenland than about the western coast. For a long time
it was supposed that there might be a considerable popu-
lation in the lower latitudes along the eastern side. But
that is now proved to be a mistake. The whole coast is
very inhospitable and difficult of approach. From lati-

* Arctic Explorations in the Years 1808, 1854, and 1855, vol. i,
pp. 225-228.

EXISTING GLACIERS. 39

tude 65° to latitude 69° little or nothing is known of it.
In 1822-23 Scoresby, Cleavering, and Sabine hastily ex-
plored the coast from latitude 69° to 76°, and reported
numerous glaciers descending to the sea-level through
extensive fiords, from which immense icebergs float out
and render navigation dangerous. In 1869 and 1870 the
second North-German Expedition partly explored the
coast between latitude 73° and 77°. Mr. Payer, an ex-
perienced Alpine explorer, who accompanied the expedi-
tion, reports the country as much broken, and the glaciers
as “ subordinated in position to the higher peaks, and hav-
ing their moraines, both lateral and terminal, like those
of the Alpine ranges, and on a still grander scale.” Peter-
mann Peak, in latitude 73°, is reported as 13,000 feet
high. Captain Koldewey, chief of the expedition, found
extensive plateaus on the mainland, in latitude 75°, to be
“ entirely clear of snow, although only sparsely covered with
vegetation.” The mountains in this vicinity, also, rising
to a height of more than 2,000 feet, were free from snow
in the summer. Some of the fiords in this vicinity pene-
trate the continent through several degrees of longitude.
An interesting episode of this expedition was the ex-
perience of the crew of the ship Hansa, which was caught
in the ice and destroyed. The crew, however, escaped by
encamping on the ice-floe which had crushed the ship.
From this, as it slowly floated towards the south through
several degrees of latitude, they had opportunity to make
many important observations upon the continent itself.
As viewed from this unique position the coast had the ap-
pearance everywhere of being precipitous, with mountains
of considerable height rising in the background, from
which numerous small glaciers descended to the sea-level.
In 1888 Dr. F’. Nansen, with Lieutenant Sverdrup and
four others, was left by a whaler on the ice-pack border-
ing the east of Greenland about latitude 65°, and in sight
of the coast. For twelve days the party was on the ice-

40 MAN AND THE GLACIAL PERIOD.

pack floating south, and so actually reached the coast only
about latitude 64°. From this point they attempted to
cross the inland ice in a northwesterly direction towards
Christianshaab. ‘They soon reached a height of 7,000
feet, and were compelled by severe northerly storms to
diverge from their course, taking a direction more to the
west. The greatest height attained was 9,500 feet, and
the party arrived on the western coast at Ameralik Fiord,
a little south of Godhaab, about the same latitude at which
they entered.

It thus appears that subsequent investigations have
confirmed in a remarkable manner the sagacious conciu-
sions made by the eminent Scotch geologist and glacialist
Robert Brown in 1875, soon after his own expedition to
the country. “I look upon Greenland and its interior
ice-field,” he writes, “in the light of a broad-lpped,
shallow vessel, but with chinks in the lips here and
there, and the glacier like viscous matter in it. As
more is poured in, the viscous matter will run over the
edges, naturally taking the line of the chinks as its line
of outflow. The broad lips of the vessel are the outlying
islands or ‘ outskirts’; the viscous matter in the vessel
the inland ice, the additional matter continually being
poured in in the form of the enormous snow covering,
which, winter after winter, for seven or eight months in
the year, falls almost continuously on it; the chinks are
the fiords or valleys down which the glaciers, represent-
ing the outflowing viscous matter, empty the surplus of
the vessel—in other words, the ice floats out in glaciers,
overflows the land in fact, down the valleys and fiords of
Greenland by force of the superincumbent weight of snow,
just as does the grain on the floor of a barn (as admirably
described by Mr. Jamieson) when another sackful is emp-
tied on the top of the mound already on the floor. ‘The
floor is flat, and therefore does not conduct the grain in
any direction; the outward motion is due to the pressure

ee

EXISTING GLACIERS. Al

of the particles of grain on one another; and, given a
floor of infinite extension and a pile of sufficient amount,
the mass would move outward to any distance, and with a
very slight pitch or slope it would slide forward along the
incline.’ ‘To this let me add that if the floor on the mar-
gin of the heap of grain was undulating the stream of
grain would take the course of such undulations. The
want, therefore, of much slope in a country and the ab-
sence of any great mountain-range are of very little mo-
ment to the movement of land-ice, provided we have snow
enough.” On another page Dr. Brown had well said that
“the country seems only a circlet of islands separated
from one another by deep fiords or straits, and bound to-
gether on the landward side by the great ice covering
which overlies the whole interior. . . . No doubt under
this ice there lies land, just as it lies under the sea; but
nowadays none can be seen, and as an insulating medium
it might as well be water.”

In his recently published volumes descriptive of the
journey across the Greenland ice-sheet, alluded to on page
39, Dr. Nansen sums up his inferences in very much the
same way: “I'he ice-sheet rises comparatively abruptly
from the sea on both sides, but more especially on the
east coast, while its central portion is tolerably flat. On
the whole, the gradient decreases the farther one gets into
the interior, and the mass thus presents the form of a
shield with a surface corrugated by gentle, almost imper-
ceptible, undulations lying more or less north and south,
and with its highest point not placed symmetrically, but
very decidedly nearer the east coast than the west.”

From this rapid glance at the existing glaciers of the
world we see that a great ice age is not altogether a
strange thing in the world. The lands about the south
pole and Greenland are each continental in dimensions,
and present at the present time accumulations of land-ice
so extensive, so deep, and so alive with motion as to pre-

49 MAN AND THE GLACIAL PERIOD.

pare our minds for almost anything that may be suggested
concerning the glaciated condition of other portions of
the earth’s surface. The vera causa is sufficient to accom-
plish anything of which glacialists have ever dreamed. It
only remains to enquire what the facts really are and over
how great an extent of territory the actual results of gla-
cial action may be found. But we will first direct more
particular attention to some of the facts and theories con-
cerning glacial motion.

CHAPIE I Ii.
GLACIAL MOTION.

THAT glacial ice actually moves after the analogy of a
semi-fluid has been abundantly demonstrated by observa-
tion. In the year 1827 Professor Hugi, of Soleure, built
a hut far up upon the Aar Glacier in Switzerland, in
order to determine the rate of its motion. After three
years he found that it had moved 330 feet; after nine
years, 2,354 feet; and after fourteen
years Louis Agassiz found that its

: GL 0d sig
motion had been 4,712 feet. In 1841 | ¢--0---0--0~-9---o--0
° ° Alou ee [ee Osa
Agassiz began a more accurate serles | o-.°~ ee
: : en Deaoste oe Oe BE
of observation upon the same glacier. |%e" ° >
Boring holes in the ice, he set PCR oe
oring holes in the ice, he set across - ee
: . 0. OFI0 *O-- 202-7
it a row of stakes which, on visiting cf pp elt
in 1842, he found to be no longer in
a straight line. All had moved down-
Fie. 16.

wards with varying velocity, those
near the centre having moved farther than the others.
The displacements of the stakes were in order, from side
to side, as follows: 160 feet, 225 feet, 269 feet, 245 feet,
210 feet, and 125 feet. Agassiz followed up his observa-
tions for six years, and in 1847 published the results in
his celebrated work System Glaciére.

But in August, 1841, the distinguished Swiss investi-
gator had invited Professor J. D. Forbes, of Edinburgh, to
interest himself in solving the problem of glacial motion.
In response to this request, Professor Forbes spent three
weeks with Agassiz upon the Aar Glacier. Stimulated

44 MAN AND THE GLACIAL PERIOD.

by the interest of this visit, Forbes returned to Switzer-
land in 1842 and began a series of independent investiga-
tions upon the Mer de Glace. After a week’s observa-
tions with accurate instruments, Forbes wrote to Professor
Jameson, editor of the Edinburgh New Philosophical
Journal, that he had already made it certain that “the
central part of the glacier moves faster than the edges in
a very considerable proportion, quite contrary to the
opinion generally maintained.” This letter was dated
July 4, 1842, but was not published until the October fol-
lowing. Agassiz’s results, so far as then determined, were,
however, published in Comptes Rendus of the 29th of
August, 1842, two months before the publication of
Forbes’s letter. But Agassiz’s letter was dated twenty-
seven days later than that of Forbes. It becomes certain,
therefore, that both Agassiz and Forbes, independently
and about the same time, discovered the fact that the
central portion of a glacier moves more rapidly than the
sides.

In 1857 Professor Tyndall began his systematic and
fruitful observations upon the Mer de Glace and other
Alpine glaciers. Professor Forbes had already demon-
strated that, with an accurate instrument of observation,
the motion of a line of stakes might be observed after
the lapse of a single day, or even of a few hours. As
a result of Tyndall’s observations, it was found that
the most rapid daily motion in the Mer de Glace in 1857
was about thirty-seven inches. This amount of motion
was near the lower end of the glacier On ascending the
glacier, the rate was found in general to be diminished;
but the diminution was not uniform throughout the
whole distance, being affected both by the size and by the
contour of the valley. The motion in the tributary gla-
clers was also much less than that of the main glacier.

This diminution of movement in the tributary glaciers
was somewhat proportionate to their increase in width.

’

GLACIAL MOTION. 45

For example, the combined width of the three tributaries
uniting to form the Mer de Glace is 2,597 yards; but a
short distance below the junction of these tributaries the
total width of the Mer de Glace itself is only 893 yards,
or one-third that of the tributaries combined. Yet, though
the depth of the ice is probably here much greater than in
the tributaries, the rapidity of movement is between two
and three times as great as that of any one of the branches.*

From Tyndall’s observations it appears also that the
line of most rapid motion is not exactly in the middle of
the channel, but is pushed by its own momentum from
one side to the other of the middle, so
as always to be nearer the concave side;
in this respect conforming, as far as its
nature will permit, to the motion of
water in a tortuous channel.

It is easy to account for this differen-
tial motion upon the surface of a glacier,
since it is clear that the friction of the
sides of the channel must retard the mo-
tion of ice as it does that of water. It
is clear also that the friction of the bot-
tom must retard the motion of ice even
more than it is known to do in the case
of water. In the formation of breakers,
when the waves roll in upon a shallow-
ing beach, every one is familiar with the
effect of the bottom upon the moving mass. Here friction
retards the lower strata of water, and the upper strata
slide over the lower, and, where the water is of sufficient
depth and the motion is sufficiently great, the crest breaks
down in foam before the ever-advancing tide. A similar
phenomenon occurs when dams give way and reservoirs
suddenly pour their contents into the restricted channels

loses ab

* See Tyndall’s Forms of Water, pp. 78-82.

46 MAN AND THE GLACIAL PERIOD.

below. At such times the advancing water rolls onwards
like the surf with a perpendicular front, varying in height
according to the extent of the flood.

Reasoning from these phenomena connected with moy-
ing water, it was naturally suggested to Professor Tyndall
that an analogous movement must take place in a glacier.
Choosing, therefore, a favourable place for observation on
the Mer de Glace where the ice emerged from a gorge, he
found a perpendicular side about one hundred and fifty
feet in height from bottom to top. In this face he drove
stakes in a perpendicular line from top to bottom. Upon
subsequently observing
them, Tyndall found,
as he expected, that

motion among them as
in the stakes upon the
surface. The retarding
effect of friction upon
the bottom was evident. The stake near the top moved
forwards about three times as fast as the one which was
only four feet from the bottom.

The most rapid motion (thirty-seven inches per day)
observed by Professor Tyndall upon the Alpine glaciers
occurred in midsummer. In winter the rate was only
about one-half as great; but in the year 1875 the Nor-
wegian geologist, Helland, reported a movement of twenty
metres (about sixty-five feet) per day in the Jakobshayn
Glacier which enters Disco Bay, Greenland, about latitude
70°. For some time there was a disposition on the part
of many scientific men to doubt the correctness of Hel-
land’s calculations. Subsequent observations have shown,
however, that from the comparatively insignificant glaciers
of the Alps they were not justified in drawing inferences
with respect to the motion of the vastly larger masses
which come down to the sea through the fiords of Green-

there was a differential °

GLACIAL MOTION. 47

land. The Jakobshavn Glacier was about two and a half
miles in width and its depth very likely more than a thou-
sand feet, making a cross-section of more than 1,400,000
square yards, whereas the cross-section of the Mer de
Glace at Montanvert is estimated to be but 190,000 square
yards or only about one-seventh the above estimate for
the Greenland glacier. As the friction of the sides
would be no greater upon a large stream than upon a
small one, while upon the bottom it would be only in pro-
portion to the area, it is evident that we cannot tell be-
forehand how rapidly an increase in the volume of the
ice might augment the velocity of the glacier.

At any rate, all reasonable grounds for distrusting the
accuracy of Helland’s estimates seem to have been re-
moved by later investigations. According to my own ob-
servations in the summer of 1886 upon the Muir Glacier,
Alaska, the central portions, a mile back from the front
of that vast ice-current, were moving from sixty-five to
seventy feet per day. These observations were taken with
a sextant upon pinnacles of ice recognizable from a base-
line established upon the shore. It is fair to add, how-
ever, that during the summer of 1890 Professor H. F.
Reid attempted to measure the motion of the same glacier
by methods promising greater accuracy than could be ob-
tained by mine. He endeavoured to plant, after the method
of Tyndall, a line of stakes across the ice-current. But
with his utmost efforts, working inwards from both sides,
he was unable to accomplish his purpose, and so left un-
measured a quarter of a mile or more of the most rapidly-
moving portion of the glacier. His results, therefore, of
ten feet per day in the most rapidly-moving portion ob-
served cannot discredit my own observations on a portion
of the stream inaccessible by his method. <A quarter of a
mile in width near the centre of so vast a glacier gives
ample opportunity for a much greater rate of motion than
that observed by Professor Reid. Especially may this be

48 MAN AND THE GLACIAL PERIOD.

true in view of Tyndall’s suggestion that the contour of
the bottom over which the ice flows may greatly affect the
rate in certain places. A sudden deepening of the chan-
nel may affect the motion of ice in a glacier as much as it
does that of water in a river. P

Other observations also amply sustain the conclusions
of Helland. As already stated, the Danish surveying party
under Steenstrup, after several years’ work upon the south-
western coast of Greenland, have ascertained that the nu-
merous glaciers coming down to the sea in that region and
furnishing the icebergs incessantly floating down Baffin’s
Bay, move at a rate of from thirty to fifty feet per day,
while Lieutenants Ryder and Bloch, of the Danish Navy,
who spent the year 1887 in exploring the coast in the
vicinity of Upernavik, about latitude 73°, found that the
- great glacier entering the fiord east of the village had a
velocity of ninety-nine feet per day during the month of
August.*

It is easier to establish the fact of glacial motion than
to explain how the motion takes place, for ice seems to be
as brittle as glass. This, however, is true of it only when
compelled suddenly to change its form. When subjected
to slow and long-continued pressure it gradually yet readi-
ly yields, and takes on new forms. From this capacity of
ice, it has come to be regarded by some as a really viscous
substance, like tar or cooling lava, and upon that theory
Professor Forbes endeavours to explain all glacial move-
ment.

The theory, however, seems to be contradicted by fa-
miliar facts; for the iceman, after sawing a shallow groove
across a piece of ice, can then split it as easily as he would
a piece of sandstone or wood. On the glaciers themselves,
likewise, the existence of innumerable crevasses would
seem to contradict the plastic theory of glacier motion;

* Nature, December 29, 1887.

+t

GLACIAL MOTION. 49

for, wherever the slope of the glacier’s bed increases, cre-
vasses are formed by the increased strain to which the ice
is subjected. Crevasses are also formed in rapidly-moving
glaciers by the slight strain occasioned by the more rapid
motion of the middle portion. Still, in the words of Tyn-
dall, “it is undoubted that the glacier moves like a viscous
body. The centre flows past the sides, the top flows over
the bottom, and the motion through a curved valley cor-
responds to fluid motion.” *

To explain this combination of the seemingly contra-
dictory qualities of brittleness and viscosity in ice, physi-
cists have directed attention to the remarkable transfor-
mations which take place in water at the freezing-point.
Faraday discovered in 1850 that “when two pieces of
thawing ice are placed together they freeze together at the
point of contact.+

“Place a number of fragments of ice in a basin of
water and cause them to touch each other; they freeze
together where they touch. You can form a chain of
such fragments; and then, by taking hold of one end of
the chain, you can draw the whole series after it. Chains
of icebergs are sometimes formed in this way in the arctic

seas.”
This is really what takes place when a hard snow-ball

is made by pressure in the hand. So, by subjecting frag-
ments of ice to pressure it is first crumbled to powder,
and then, as the particles are pressed together in close
contact, it resumes the nature of ice again, though in a
different form, taking now the shape of the mould in
which it has been pressed.

Thus it is supposed that, when the temperature of ice
is near the melting-point, the pressure of the superincum-
bent mass may produce at certain points imsensible disin-
tegration, while, upon the removal of the pressure by

* Forms of Water, p. 163. + Ibid., p. 164. t Ibid., pp. 164, 160.
5

50 MAN AND THE GLACIAL PERIOD.

change of position, regelation instantly takes place, and
thus the phenomena which simulate plasticity are pro-
duced. As the freezing-point of water is, within a narrow
range, determined by the amount of pressure to which it
is subjected, it is not difficult to see how these changes
may occur. Pressure slightly lowers the freezing-point,
and so would liquefy the portions of ice subjected to great-
est pressure, wherever that might be in the mass of the
glacier, and thus permit a momentary movement of the
particles, until they should recongeal in adjusting them-
selves to spaces of less pressure.* This is the theory by
which Professor James Thompson would account for the
apparent plasticity of glacial ice.

* Forms of Water, p. 168.

Cele lesuadey, IOV
SIGNS OF PAST GLACIATION.

THE facts from which we draw the inference that vast
areas of the earth’s surface which are now free from gla-
ciers were, at a comparatively recent time, covered with
them, are fourfold, and are everywhere open to inspection.
These facts are: 1. Scratches upon the rocks. 2. Exten-
sive unstratified deposits of clay and sand intermingled
with scratched stones and loose fragments of rock. 3.
Transported boulders left in such positions and of such
size as to preclude the sufficiency of water-carriage to
account for them. 4. Extensive gravel terraces bordering
the valleys which emerge from the glaciated areas. We
will consider these in their order :

1. The scratches upon the rocks.

Almost anywhere in the region designated as having
been covered with ice during the Glacial period, the sur-
face of the rocks when freshly uncovered will be found to
be peculiarly marked by grooves and scratches more or
less fine, and such as could not be produced by the action
of water. But, when we consider the nature of a glacier,
these marks seem to be just what would be produced
by the pushing or dragging along of boulders, pebbles,
gravel, and particles of sand underneath a moving mass
of ice.

Running water does indeed move gravel, pebbles, and
boulders along with the current, but these objects are not
held by it in a firm grasp, such as is required to make a
groove or scratch in the rock. If, also, there are inequali-

52 MAN AND THE GLACIAL PERIOD.

ties in the compactness or hardness of the rock, the
natural action of running water is to hollow out the soft
parts, and leave the harder parts projecting. But, in the
phenomena which we are attributing to glacial action,
there has been a movement which has steadily planed

Fie. 19.—Bed-rock scored with glacial marks, near Amherst, Ohio. (From a pho-
tograph by Chamberlin.)

down the surface of the underlying rock; polishing it,
indeed, but also grooving it and scratching it in a man-
ner which could be accomplished only by firmly held
eraving-tools. : -
This polishing and scratching can indeed be produced

SIGNS OF PAST GLACIATION. 53

by various agencies; as, for example, by the forces which
fracture the earth’s crust, and shove one portion past
another, producing what is called a slicken-side. Or,
again, avalanches or land-slides might be competent to
produce the results over limited and peculiarly situated
areas. Icebergs, also, and shore ice which is moved back-
wards and forwards by the waves, would produce a cer-
tain amount of such grooving and scratching. But the
phenomena to which we refer are so extensive, and occur
in such a variety of situations, that the movement of
glacial ice is alone sufficient to afford a satisfactory ex-
planation. Moreover, in Alaska, Greenland, Norway,
and Switzerland, and wherever else there are living
glaciers, it is possible to follow up these grooved and
striated surfaces till they disappear underneath the ex-
isting glaciers which are now producing the phenom-
ena. Thus by its tracks we can, as it were, follow
this monster to its lair with as great certainty as we
could any animal with whose footprints we had become
familar.

2. The till, or boulder-clay.

A second sign of the former existence of glaciers over
any area consists of an unstratified deposit of earthy
material, of greater or less depth, in which scratched
pebbles and fragments of rock occur without any definite
arrangement.

Moving water is a most perfect sieve. During floods,
a river shoves along over its bed gravel and pebbles of
considerable size, whereas in time of low water the cur-
rent may be so gentle as to transport nothing but fine
sand, and the clay will be carried still farther onwards, to
settle in the still water and form a delta about the river’s
mouth. The transporting capacity of running water is
in direct ratio to the sixth power of its velocity. Other
things being equal, if the velocity be doubled, the size of
the grains of sand or gravel which it transports is in-

BA MAN AND THE GLACIAL PERIOD.

creased sixty-four fold.* So frequent are the changes in
the velocity of running water, that the stratification of
its deposits is almost necessary and universal. If large

Fie. 20.—Scratched stone from the till of Boston. Natural size about one foot

and a half long by ten inches wide. (Krom photograph.) ;

fragments of rocks or boulders are found embedded in
stratified clay, it is pretty surely a sign that they have
been carried to their position by floating ice. A small
mountain stream with great velocity may move a good-
sized boulder, while the Amazon, with its mighty but
slow-moving current, would pass by it forever without

* Le Uonte’s Geology, p. 19.

SIGNS OF PAST GLACIATION. 55

stirring it from its position. But the vast area which is
marked in our map as having been covered with ice dur-
ing the Glacial period is characterised by deep and exten-

wR
yy ye
i

Wh

Wie. 21.—Typical section of till in Seattle, Washington State, about two hundred
feet above Puget Sound. This is on the height between the sound and Lake
Washington.

56 MAN AND THE GLACIAL PERIOD.

sive deposits of loose material devoid of stratification, and
composed of soil and rock gathered in considerable part
from other localities, and mixed in an indiscriminate
mass with material which has originated in the disinte-
gration of the underlying local strata.

Fig. 22.—Ideal section, showing how the till overlies the stratified rocks.

3. Transported boulders.

Where there is a current of water deep enough to float
large masses of ice, there is scarcely any limit to the size
of boulders which may be transported upon them, or to

ae)

Fie. 23.—Vessel Rock, a glacial boulder in Gilsum, N. H. (C. H. Hitchcock.)

the distance to which the boulders may be carried and
dropped upon the bottom. The icebergs which break off
from the glaciers of Greenland may bear their burdens of
rock far down into the Atlantic, depositing them finally
amidst the calcareous ooze and the fine sediment from the

SIGNS OF PAST GLACIATION, 57

Gulf Stream which is slowly covering the area between
Northern America and Europe. Northern streams like
the St. Lawrence, which are deeply frozen over with ice
in the winter, and are heavily flooded as the ice breaks up
in the spring, afford opportunity for much transportation
of boulders in the direction of their current. In attribut-
ing the transportation of a boulder to glacial ice, it is
necessary, therefore, to examine the contour of the coun-
try, so as to eliminate from the problem the possibility of
the effects having been produced by floating ice.

Another source of error against which one has to be
on his guard arises from the close resemblance of boulders
resulting from disintegration to those which have been
transported by ice from distant places. Owing to the
fact that large masses of rocks, especially those which are
crystalline, are seldom homogeneous in their structure, it
results that, under the slow action of disintegrating and
erosive agencies, the softer parts often are completely re-
moved before the harder nodules are sensibly affected,
and these may remain as a collection of boulders dotting
the surface. Such boulders are frequent in the granitic
regions of North Carolina and vicinity, where there has
been no glacial transportation. Several localities in Penn-
sylvania, also, south of the line of glacial action as de-
lineated by Professor Lewis and myself, had previously
been supposed to contain transported boulders of large
size, but on examination they proved in all cases to be
resting upon undisturbed strata of the parent rock, and
were evidently the harder portions of the rock left 2 loco
by the processes of erosion spoken of. In New England,
also, it is possible that some boulders heretofore attributed
to ice-action may be simply the results of these processes
of disintegration and erosion. Whether they are or not
can usually be determined by their likeness or unlikeness
to the rocks on which they rest; but oftentimes, where a
particular variety of rock is exposed over a broad area, it

6

58 MAN AND THE GLACIAL PERIOD.

is difficult to tell whether a boulder has suffered any ex-
tensive transportation or not.

One of the most interesting and satisfactory demon-
strations of the distribution of boulders by glacial ice was
furnished by Guyot in Switzerland in 1845. His observa-

tions and argument
will be most readily
understood by refer-
ence to the accom-
panying map, taken
from Lyell’s clear de-
seription.* The Jura
Mountains are sepa-
rated from the Alps
by a valley, about
eighty miles in width,
which constitutes the
main habitable por-
Fic. 24.—Map showing the outline and course of tion of Switzerland,

flow of the great Rhéne Glacier (after Lyell). and they rise upwards
of two thousand feet above it. But large Alpine boulders
are found as high as two thousand feet above the Lake
Neufchatel upon the flanks of the Jura Mountains beyond
Chasseron (at the point marked G on the map), and the
whole valley is dotted with Alpine boulders. Upon com-
paring these with the native rocks in the Alps, Guyot in
many cases was able to determine the exact centres from
which they were distributed, and the distribution is such
as to demonstrate that glacial ice was the medium of dis-
tribution.

For example, the dotted lines upon the map indicate
the motion of the transporting medium. On ascending

the valley of the Rhone to A, the diminutive representa- ©

tive of the ancient glacier is still found in existence, and

* Antiquity of Man, p. 299.

SIGNS OF PAST GLACHATION. 59

is at work transporting boulders and moraines according
to the law of ice-movement. Following down the valley
from A, boulders from the head of the Rhone Valley are
found distributed as far as B at Martigny, where the val-
ley turns at right angles towards the north. It is evident
that floating ice in a stream of water would by its momen-
tum be carried to the left bank, so that if icebergs were
the medium of transportation we should expect to find
the boulders from the right-hand side of the Rhone Val-
ley distributed towards the left end of the great valley of
Switzerland—that is, in the direction of Geneva. But,
instead, the boulders derived from C, D, and E, on the
Bernese Oberland side, instead of crossing the valley at
B, continue to keep on the right-hand side and are dis-
tributed over the main valley in the direction of the river
Aar.

As is to be expected also, the direct northward motion
of the ice from B is stronger than the lateral movement to
the right and left after it emerges from the mouth of the
Rhone Valley, at F, and consequently it has pushed for-
wards in a straight line, so as to raise the Alpine boulders
to a greater height upon the Jura Mountains at G than
anywhere else, the upper limit of boulders at G being
1,500 feet higher than the limits at I or K on the left and
right, points distant about one hundred miles from each
other. All the boulders to the right of the line from B to
G have been derived from the right side of the Rhone,
while all the boulders to the left of that line have been
derived from its left side.

A boulder of talcose granite containing 61,000 French
cubic feet, measuring about forty feet in one direction,
came, according to Charpentier, from the point », near
the head of the Rhéne Valley, and must have travelled
one hundred and fifty miles to reach its present position.

It scarcely needs to be added that the grooves and
scratches upon the rocks over the floor of this great valley

60 MAN AND THE GLACIAL PERIOD.

of Switzerland indicate a direction of the ice-movement
corresponding to that implied in the distribution of boul-
ders. ‘Thus, at K upon the map referred to, Lyell reports
that the abundant grooves and striz upon the polished
marble all trend down the valley of the Aar.*

Similar facts concerning the transportation of boul-
ders have been observed at Trogen, in Appenzel, where
boulders derived from Trons, one hundred miles distant,
are found to keep upon the left bank of the Rhine, how-
ever much the valley may wind about; and in some places,
as at Mayenfeld, it turns almost at right angles, as did the
Rhone at Martigny. Upon reaching the lower country at
Lake Constance, these granite blocks from the left side of
the valley deploy out upon the same side and do not cross
over, as they would inevitably have done had they been
borne along by currents of water.

In America we do not have quite so easy a field as is
presented in Switzerland for the discovery of crucial in-
stances showing that boulders have been transported by
glacial ice rather than by floating ice, for in Switzerland
the glaciated area is comparatively small and the diminu-
tive remnants of former glaciers are still in existence, fur-
nishing a comprehensive object-lesson of great interest
and convincing power. Still, it is not difficult to find
decisive instances of glacial transportation even in the
broad fields of America which now retain no living rem-
nants of the great continental ice-sheet.

As every one who resides in or who visits New England
knows, boulders are scattered freely over all parts of that
region, but for a long time the theory suggested to ac-
count for their distribution was that of floating ice during
a period of submergence. One of the most convincing
evidences that the boulders were distributed by glacial ice
_ rather than by icebergs is found in Professor C. H. Hitch-

* Antiquity of Man, p. 309.

SIGNS OF PAST GLACEATION. 61

cock’s discovery of boulders on the summit of Mount
Washington (over 6,000 feet above the sea), which he was
able to identify as derived from the ledges of light grey
Bethlehem gneiss, whose nearest outcrop is in Jefferson,
several miles to the northwest, and 3,000 or 4,000 feet
lower than Mount Washington. However difficult it may
be to explain the movement of these boulders by glacial
ice, it is not impossible to do so, but the attempt to ac-
count for their transportation by floating ice is utterly
preposterous. No iceberg could pick up boulders so far
‘beneath the surface of the water, and even if it could ad-
vance thus far in its work it could not by any possibility
land them afterwards upon the summit of Mount Wash-
ington.

Among the most impressive instances of boulders evi-
dently transported by glacial ice, rather than by icebergs,
were some which came to my notice when, in company
with the late Professor H. Carvill Lewis, I was tracing the
glacial boundary across the State of Pennsylvania. We
had reached the elevated plateau (two thousand feet above
the sea) which extends westwards and southwards from
the peak of Pocono Mountain, in Monroe County. This
plateau consists of level strata of sandstone, the southern
part of which is characterised by a thin sandy soil, such
as is naturally formed by the disintegration of the under-
lying rock, and there is no foreign material to be found
in it. But, on going northwards to the boundary of Toby-
hanna township, we at once struck a large line of accumu-
lations, stretching from east to west, and rising to a height
of seventy or eighty feet. This was chiefly an accumula-
tion of transported boulders, resembling in its structure
the terminal moraines which are found at the front of
glaciers in the Alps and in Alaska, and indeed wherever
active glaciers still remain. But here we were upon the
summit of the mountain, where there are no higher levels
to the north of us, down which the ice could flow. Be-

62 MAN AND THE GLACIAL PERIOD.

sides, among these boulders we readily recognised many of
granite, which must have come either from the Adiron-
dack Mountains, two hundred miles to the north, or from
the Canadian highlands, still farther away.

Limiting our observations simply to the boulders, we
should indeed have been at liberty to suppose that they
had been transported across the valley of the Mohawk or
of the Great Lakes by floating ice during a period of sub-
mergence. But we were forbidden to resort to this hy-
pothesis by the abrupt marginal line, running east and
west, upon Pocono plateau, along which these northern
boulders ceased. South of this evident terminal moraine
there was no barrier, and there were no northern boulders.
On the theory of submergence, there was no reason for
the boundary-line so clearly manifested. Ice which had
floated so far would have floated farther.

Still further, on going a few miles east of the Pocono
plateau, one descends into a parallel valley, lying between
Pocono Mountain and Blue Mountain, and one thousand
feet below their level. But our marginal southern bound-
ary of transported granite rocks did not extend much
- farther south in the valley than it did on the plateau,
except where we could trace the action of a running
stream, evidently corresponding to the subglacial rivers
which pour forth from the front of every extensive glacier.
In these facts, therefore, we had a crucial test of the
glacial hypothesis, and, in view of them, could maintain,
against all objectors, the theory of the distant glacial
transportation of boulders, even over vast areas of the
North American continent.

Since that experience, I have traced this limit of
southern boulders for thousands of miles across the con-
tinent, according to the delineation which may be seen in
the map in a later chapter. If necessary, I could indi-
cate hundreds of places where the proof of glacial trans-
portation is almost as clear as that on the Pocono plateau

SIGNS OF PAST GLACIATION. 63

in Pennsylvania. One of the most interesting of these is
on the hills in Kentucky, about twelve miles south of the
Ohio River, at Cincinnati, where I discovered boulders of
a conglomerate containing many pebbles of red jasper,
which can be identified as from a limited formation crop-

Fig. 25.—Conglomerate boulder found in Boone County, Kentucky. (See text.)

ping out in Canada, to the north of Lake Huron, six
hundred or seven hundred miles distant. That this was
transported by glacial ice, and not by floating ice, is evi-
dent from the fact that here, too, there was no barrier to
the south, requiring deposits to cease at that point, and
from the further fact that boulders of this material are
found in increasing frequency all the way from Kentucky
to the parent ledges in Canada. With reference to these
boulders, as with reference to those found on the summit
of Mount Washington, we can reason, also, that any
northerly subsidence permitting a body of water to occupy
the space between Kentucky and Lake Superior, and deep

64 MAN AND THE GLACIAL PERIOD.

enough to facilitate the movement across it of floating
ice, would render it impossible for the ice to have loaded
itself with them.

The same line of reasoning is conclusive respecting the
innumerable boulders which cover the northern portion
of Ohio, where I have my residence. The whole State of
Ohio, and indeed almost the entire Mississippi basin be-
tween the Appalachian and the Rocky Mountains, is com-
pletely covered, and to a great depth, with stratified rocks
which have been but slightly disturbed in the elevation of
the continent; yet, down to an irregular border-line run-
ning east and west, granitic boulders everywhere occur in
ereat numbers. In the locality spoken of in northern
Ohio the elevation of the country is from two hundred to
five hundred feet above the level of Lake Erie. ‘The near-
est outcrops of granitic rock occur about four hundred miles
to the north, in Canada. After the meeting of the Ameri-
can Association for the Advancement of Science in To-
ronto in the summer of 1889, I had the privilege of join-
ing a company of geologists in an excursion, conducted
by members of the Canadian Survey, to visit the region
beyond Lake Nipissing, north of Lake Huron, where the
ancient Laurentian and Huronian rocks are most typically
developed. I took advantage of the trip to collect speci-
mens of a great variety of the granites and gneisses and
metamorphic schists and trap-rock of the region. On
bringing them home I turned them over to the professor
of geology, who at once set his class at work to see if they
could match my fragments from Canada with correspond-
ing fragments from the boulders of the vicinity. To the
great gratification, both of the pupils and myself, they
were able to do so in almost every case; and so they might
have done in any county or township to the south until
reaching the limit of glacier action which I had previously
mapped. Here, at Oberlin, on the north side of the water-
shed, it is possible to imagine that we are on the southern

SIGNS OF PAST GLACIATION. 65

border of an ancient lake upon whose bosom floating ice
had brought these objects from their distant home in
Canada. But this theory would not apply to the portion
of the State which is south of the water-shed and which
slopes rapidly towards the Gulf of Mexico. Yet the dis-
tribution of boulders is practically uniform over the gla-
ciated area on both sides of the water-shed, constituting
thus an indisputable proof of the glacial theory.

4th. As the significance of the gravel terraces which
mark the hnes of outward drainage from the glaciated
area cannot well be indicated in a single paragraph, the
reader is referred for further information upon this point
to the general statements respecting them throughout the
next chapter.

CEUAPALR eve
ANCIENT GLACIERS IN THE WESTERN HEMISPHERE.
New England.

In North America all the indubitable signs of glacial
action are found over the entire area of New England, the
southern coast being bordered bya double line of terminal
moraines. The outermost of these appears in Nantucket,
Martha’s Vineyard, No Man’s Land, Block Island, and
through the entire length of Long Island—from Montauk
Point, through the centre of the island, to Brooklyn,
N. Y.,and thence across Staten Island to Perth Amboy in
New Jersey. ‘The interior line is nearly parallel with the
outer, and, beginning at the east end of Cape Cod, runs
in a westerly direction to Falmouth, and thence south-
westerly through Wood’s Holl, and the Elizabeth Islands
—these being, indeed, but the unsubmerged portions of
the moraine. On the mainland this interior line reap-
pears near Point Judith, on the south shore of Rhode
Island, and, running slightly south of west, serves to give
character to the scenery at Watch Hill, and thence crops
out in the Sound as Fisher and Plum Islands, and farther
west forms the northern shore of Long Island to Port Jef-
ferson.

In these accumulations bordering the southern shore
of New England, the characteristic marks of glacial action
can readily be detected even by the casual observer, and
prolonged examination will amply confirm the first 1m-
pression. The material of which they are composed is,

—
ee

4

2 East

Longitude

0

————{ 1

THE
GLACIAL GEOLOGY
OF THE
UNITED STATES.

Southern Limit of the Ice:sheet and Drift.

Terminal Moraines.

Courses of Glacial Strie and Transporta-
tion of Boulders.

GG Driftless Area of Wisconsin.

Modified Drift in valleys of southward
drainage from the Ice-sheet.

Boundary of the Glacial Lake Agassiz.

oul

ISI AN Aj

Washington 4

ANCIENT GLACIERS; 67

for the most part, foreign to the localities, and can be
traced to outcrops of rock at the north. The boulders
scattered over the surface of Long Island, for example,
consist largely of granite, gneiss, hornblende, mica slate,
and red sandstone, which are easily recognised as frag-
ments from well-known quarries in Connecticut, Rhode
Island, and Massachusetts; yet they have been transported
bodily across Long Island Sound, and deposited in a het-
erogeneous mass through the entire length of the island.
Not only do they le upon the surface, but, in digging into
the lines of hills which constitute the backbone of Long
Island, these transported boulders are found often to make
up a large part of the accumulation. Almost any of the
railroad excavations in the city of Brooklyn present an
interesting object-lesson respecting the composition of a
terminal moraine. 7

All these things are true also of the lnes of moraine
farther east, as just described. Professor Shaler has traced
to its source a belt of boulders occurring extensively over
southern Rhode Island, and found that they have spread
out pretty evenly over a triangular area to the southward,
in accordance with the natural course to be pursued by an
ice-movement. Nearly all of Plymouth County, in south-
eastern Massachusetts, is composed of foreign material,
much of which can be traced to the hills and mountains
to the north. Even Plymouth Rock is a boulder from the
direction of Boston, and the ‘“ rock-bound ” shores upon
which the Pilgrims are poetically conceived to have land-
ed are known, in scientific prose, as piles of glacial rub-
bish dumped into the edge of the sea by the great conti-
nental ice-sheet.

The whole area of southeastern Massachusetts is dot-
ted with conical knolls of sand, gravel, and boulders, sepa-
rated by circular masses of peat or ponds of water, whose
origin and arrangement can be accounted for only by the -
peculiar agency of a decaying ice-front.- Indeed, this

68 MAN AND THE GLACIAL PERIOD.

whole line of moraines, from the end of Cape Cod to
Brooklyn, N. Y., consists of a reticulated network of
ridges and knolls, so deposited by the ice as to form in-
numerable kettle-holes which are filled with water where
other conditions are favourable.. Those which are dry are
so because of their elevation above the general level, and
of the looseness of the surrounding soil; while many have
been filled with a growth of peat, so that their original
character as lakelets is disguised.

As already described, these depressions, so characteris-
tic of the glaciated region, are, in the majority of cases,
supposed to have originated by the deposition of a great
quantity of earthy material around and upon the masses
of ice belonging to the receding front of the glacier, so
that, when at length the ice melted away, a permanent de-
pression in the soil was left, without any outlet.

To some extent, however, the kettle-holes may have
been formed by the irregular deposition of streams of wa-
ter whose courses have crossed each other, or where eddies
of considerable force have been produced inany way. The
ordinary formation of kettle-holes can be observed in prog-
ress on the foot of almost any glacier, or, indeed, on a small
scale, during the melting away of almost any winter’s snow.
Where, from any cause, a stratum of dirt has accumulated
upon a mass of compact snow or ice, it will be found to
settle down in an irregular manner; furrows will be formed
in various directions by currents of water, so that the melt-
ing will proceed irregularly, and produce upon a miniature
scale exactly what I have seen on a large scale over whole
square miles of the decaying foot of the great Muir Glacier
in Alaska. The effects of similar causes and conditions
we can see on a most enormous scale in the ten thousand
lakes and ponds and peat-bogs of the whole glaciated
area both in North America and in Europe.

In addition to these two lines of evidence of glacial
action in New England, we should mention also the in-

ANCIENT GLACIERS. 69

numerable glacial grooves and scratches upon the rocks
which can be found on almost any freshly uncovered sur-
face. In New England the direction of these grooves is
ordinarily a little east of south. Upon the east coast of
Massachusetts and New Hampshire the scratches trend
much more to the east than they do over most of the in-
terior. ‘This is as it should be on the glacial theory, since
the ice would naturally move outwards in the line of least
resistance, which would, of course, be towards the open sea
wherever that is near. In the interior of New England
the scratches upon the rocks indicate a more southerly
movement in the Connecticut Valley than upon the
mountains in the western part of Massachusetts. This
also is as it should be upon the glacial theory. The
scratches upon the mountains were made when the ice
was at its greatest depth and when it moved over the
country in comparative disregard of minor irregularities
of surface, while in the valleys, at least in the later por-
tion of the Ice age, the movement would be obstructed
except in one direction. In the interpretation of the
glacial grooves and scratches it should be borne in mind
that they often represent the work done during the clos-
ing stages of the period. Just as the last shove of the
carpenter’s plane removes the marks of the previous
work, so the last rasping of a glacial movement wears
away the surfaces which have been previously polished
and striated.

In various places of New England it is interesting as
well as instructive to trace the direction of the ice-move-
ment by the distribution of boulders. My own atten-
tion was early attracted to numerous fragments of gneiss
in eastern Massachusetts containing beautiful crystals of
feldspar, which proved to be peculiar to the region of
Lake Winnepesaukee, a hundred miles to the north, and
to a narrow belt stretching thence to the southwestward.
In ascending almost any of the lower summits of the

Wil) MAN AND THE GLACIAL PERIOD.

White Mountains one’s attention can scarcely fail of be-
ing directed to the difference between the. material of
which the mountains are composed and that of the nu-
merous boulders which lie scattered over the surface.
The local geologist readily recognises these boulders as
pilgrims that have wandered far from their homes to the
northward.

Trains of boulders, such as those already described in
Rhode Island, can frequently be traced to some prominent
outcrop of the rock in a hill or mountain-peak from which
they have been derived. One of the earliest of these to
attract attention occurs in the towns of Richmond, Lenox,
and Stockbridge, in the western part of Massachusetts.
Here a belt of peculiar boulders about four hundred feet
wide is found to originate in the town of Lebanon, N. Y.,
and to run continuously to the southeast for a distance of
nine miles. West of Fry’s Hill, where the outcrop occurs,
no boulders of this variety of rock are to be found, while
to the southeast the boulders gradually diminish in size as
their distance from the outcrop increases. Near the out-
crop boulders of thirty feet in diameter occur, while nine
miles away two feet is the largest diameter observed.

Sir Charles Lyell endeavoured to explain this train of
boulders by the action of icebergs during a period of sub-
mergence—supposing that, as icebergs floated past or

away from this hill in Lebanon, N. Y., they were the

means of the regular distribution described. It is need-
less to repeat the difficulties arising in connection with
such a theory, since now both by observation and experi-
ment we have become more familiar with the movement of
glacial ice. What we have already said about the trans-
portation of boulders over Switzerland by the Alpine
glaciers, and what is open to observation at the present
time upon the large glaciers of Alaska, closely agree with
the facts concerning this Richmond train of boulders, and
we have no occasion to look further for a cause.

ANCIENT GLACIERS. val

Indeed, trains of boulders ought to appear almost
everywhere over the glaciated area; and so they do where
all the circumstances are favourable. But, readily to iden-
tify the train, requires that to furnish the boulders there
should be in the line of the ice-movement a projecting
mass of rock hard enough to offer considerable resistance
to the abrading agency of the ice and characteristic enough
in its composition to be readily recognised. Ship Rock,
in Peabody, Mass., weighing about eleven hundred tons,
and Mohegan Rock, in Montville, Conn., weighing about
ten thousand tons, have ordinarily been pointed to as
boulders illustrating the power of ice-action. Their glacial
character, however, has been challenged from the fact that
the variety of granite to which they belong occurs in the
neighbourhood, and indeed constitutes the bed-rock upon
which they rest.* Some would therefore consider them.
like some of which we have already spoken, to be boulders
which have originated through the disintegration of great
masses of rock, of which these were harder nuclei that
have longer resisted the ravages of the tooth of time. It
must be admitted that possibly this explanation is correct ;
but it is scarcely probable that, in a region where there
are so many other evidences of glacial action, these boul-
ders could have remained immovable in presence of the
onward progress of the ice-current that certainly passed
over them.

However, as already seen, we are not left to doubt as
to the movement of some boulders of great size. That
which now claims the reputation of being the largest in
New England is in Madison, N. H., and measures thirty
by forty by seventy-five feet. This can be traced to
ledges of Conway granite, about two miles away.t Many
boulders in the vicinity of New Haven, Conn., can be

* Popular Science Monthly, vol. xxxvii, pp. 196-201.
t See W. O. Crosby’s paper in Appalachia, vol. vi, pp. 59-70,

72 MAN AND THE GLACIAL PERIOD.

identified, as from well-known trap-dykes, sixteen miles
or more to the north. The so-called Judge’s Cave, on
West Rock, 365 feet above the adjoining valley and
weighing a thousand tons, is one of these. Professor Kd-

Fig. 26.—Mohegan Rock.

ward Orton * describes a mass of Clinton limestone near
Freeport, Warren County, Ohio, as covering an area of
three-fourths of an acre, and as sixteen feet in thickness,
It overlies glacial clays and gravels, and must have been
transported bodily from the elevations containing this
rock several miles to the northwest.

x

* Geological Survey of Ohio, vol. iii, p. 885,

ANCIENT GLACIERS. 73

rene

Portions of New England present the best illustra-
tions anywhere afforded in America of what are called
“drumlins.” These are “lenticular-shaped” hills, com-
posed of till, and containing, interspersed through their
mass, numerous scratched stones of all sizes. ‘They vary
in length from a few hundred feet to a mile, and are usu-
ally from half to two-thirds as wide as they are long. In
height they vary from twenty-five to two hundred feet.

But, according to the description of Mr. Upham, what-
ever may be their size and height, they are singularly
alike in outline and form, usually having steep sides, with
gently sloping, rounded tops, and presenting a very
smooth and regular contour. From this resemblance in
shape to an elliptical convex lens, Professor Hitchcock
has called them Jenticular hills to distinguish these de-
posits of till from the broadly flattened or undulating
sheets which are common throughout New England.

Fie. 27.—Drumlins in Goffstown, N. H. (Hitchcock).

The trend, or direction of the longer axis, of these
lenticular hills is nearly the same for all of them com-
prised within any limited area, and is approximately like
the course of the strive or glacial furrows marked upon
the neighbouring ledges. In eastern Massachusetts and

‘yy ht iso, :
- :
P

74 MAN AND THE GLACIAL PERIOD,

New Hampshire, within twenty-five miles of the coast, it
is quite uniformly to the southeast, or east-southeast.
Farther inland, in both of these States, it is generally
from north to south, or a few degrees east of south; while
in the valley of the Connecticut River it is frequently a
little to the west of south. In New Hampshire, besides
its accumulation in these hills, the till is frequently
amassed in slopes of similar lenticular form. These have
their position almost invariably upon either the south or
north side of the ledgy hills against which they rest, show-
ing a considerable deflection towards the southeast and
northwest in the east part of the State. It cannot be
doubted that the trend of the lenticular hills, and the
direction taken by these slopes, have been determined by
the glacial current, which produced the striz with which °
they are parallel.*

Drumlins are abundant in the vicinity of Boston, and
constitute nearly all the islands in Boston Harbour. On
the mainland, Beacon Hill, Bunker Hill, Green Hill, Pow-
derhorn Hill, Tufts College Hill, Winter Hill, Mount Ida,
Corey Hill, Parker Hill, Wollaston Heights, Prospect Hill,
and ‘Telegraph Hill are specimens.

The northeastern corner of Massachusetts and the
southeastern corner of New Hampshire are largely cov-
ered with these peculiar-shaped glacial deposits, while
they are numerous as far west as Fitchburg, in Massachu-
setts, and Ware, N. H., and in the northeastern part of
Connecticut. A little later, also, we shall refer to an in-
teresting line of them in central New York. LHlsewhere
in America, except in a portion of Wisconsin, they rarely
occur in such fine development as in New England. In
Europe they are best developed in portions of Ireland.

One’s first impression in examining an exposed section

* Proceedings of the Boston Society of Natural History, vol. xx,
pp. 224, 225,

ANCIENT GLACIERS. 5

of a drumlin would lead him to think that the mass was
entirely unstratified; but closer examination shows that

Qe ,
/B OOKLINE

Fie. 28.—Drumlins in the vicinity of Boston (Davis).

there is a coarse stratification, but evidently not produced
by water-action. ‘The accumulation has probably taken
place gradually by successive deposits underneath the
glacier itself. Professor Wiluam M. Davis has suggested
a plausible explanation which we will briefly state.

The frequency with which drumlins are found to rest
upon a mass of projecting rock, the general co-ordination
of the direction of their axes with the direction of the
scratches upon the underlying rock, and the abundance
of scratched stones in them, all support the theory that
drumlins are formed underneath the ice-sheet, somewhat
in the way that islands and bars of silt are formed in the
delta of a great river. The movement of ice seems to

6 MAN AND THE GLACIAL PERIOD.

have been concentrated in pretty definite lines, often de-
termined by the contour of the bottom, leaving a slacker
movement in intervening areas, which were evidently pro-
tected in some cases by projecting masses of rock. In
these areas of slower movement there was naturally an
accumulation at the same time that there was vigorous
erosion in the lines of more rapid movement.

There was doubtless a continual transfer of material
from the end of the drumlin which abutted against the
moving mass of ice to the lower end, as there is in the
formation of an island in a river. If time enough had
elapsed, the whole accumulation would have been levelled
by the glacier and spread over the broader area where the
more rapid lines of movement became confluent, and
where the differential motion was less marked. Drumlins
are thus characteristic of areas in the glaciated region
whose floor was originally only moderately irregular, and
where there was an excessive amount of ground moraine
to be transported, and where the movement did not con-
tinue indefinitely. It has been suggested, also, that some
of the long belts of territory in New England and central
New York covered by drumlins may represent old terminal
moraines which were subsequently surmounted by a re-
advance of the ice, and partially wrought over into their
present shape.

It is in New England, also, that kames are to be found
in better development than anywhere else in America.
These interesting remnants of the Glacial age are clearly
described by Mr. James Geikie. His account will serve
as well for New England as for Scotland.

The sands and gravels have a tendency to shape them-
selves into mounds and winding ridges, which give a
hummocky and rapidly undulating outline to the ground.
Indeed, so characteristic is this appearance, that by it
alone we are often able to mark out the boundaries of the
deposits with as much precision as we could were all the

ANCIENT GLACIERS. 1a

vegetation and soil stripped away and the various subsoils
laid bare. Occasionally, ridges may be tracked continu-
ously for several miles, running like great artificial ram-
parts across the country. ‘These vary in breadth and

Fie. 29.—Section of kame near Dover, New Hampshire. Length, three hundred
feet ; height, forty feet; base, about forty feet above the Cocheco River, or
seventy-five feet above the sea. a, a, gray clay; 6, fine sand; c, ¢, coarse
gravel containing pebbles from six inches to one foot and a half in diameter;
d, d, fine gravel (Upham),

height, some of the more conspicuous ones being upward
of four or five hundred feet broad at the base, and sloping
upward at an angle of twenty-five or even thirty-five de-
grees, to a height of sixty feet and more above the general
surface of the ground. It is most common, however, to
find mounds and ridges confusedly intermingled, crossing
and recrossing each other at all angles, so as to enclose
deep hollows and pits between. Seen from some dominant
point, such an assemblage of kames, as they are called,
looks like a tumbled sea—the ground now swelling into
long undulations, now rising suddenly into beautiful peaks
and cones, and anon curving up in sharp ridges that often
wheel suddenly round so as to enclose a lakelet of bright
clear water.*

In New England attention was first directed to kames
in 1842, by President Edward Hitchcock, in a paper be-
fore the American Association of Geologists and Natural-
ists, describing the gravel ridges in Andover, Mass. In
the accompanying plate is shown a portion of this kame
system, which has a double interest to me from the fact
that it was while living upon the banks of the Shawshin

* The Great Ice Age, pp. 210, 211,

J

78

MAN AND THE GLACIAL PERIOD.

River, near where the kames and the river intersect, that I
began, in 1874, my special study of glacial deposits. The

ANDOVER

KAMES

MASS.

One Half Mile.

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Fie. 30.

Andover ridges are composed of imperfectly stratified
water-worn material, and-are very sharply defined, from

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80 MAN AND THE GLACIAL PERIOD.

the town of Chelsea, back from the coast into New Hamp-
shire, for a distance of twenty-five miles. The base of the
ridges does not maintain a uniform level, but the system
descends into shallow valleys, and rises over elevations of
one hundred to two hundred feet, without interruption.
This indifference to slight changes of level is specially
noticeable where the system crosses the Merrimac River,
just above the city of Lawrence. * It is also represented in
the accompanying plate, where the base of the ridges in
the immediate valley of the Shawshin is fifty feet lower
than the base of those a short distance to the north, at
the points marked a, 6, and c. ‘The ridges here terminate
at the surface in a sharp angle, and are above their base
forty-one feet at a, forty-nine feet at 6, and ninety-one feet
atc. Between ¢ and 0 there is an extensive peat-swamp,
filling the depression up to the level of an outlet through
which the surplus water has found a passage.

Several systems of kames approximately parallel to
this have been traced out in Massachusetts and New
Hampshire, while the remnants of a very extensive sys-
tem are found in the Connecticut Valley above the Mas-
sachusetts line. But they abound in greatest profusion
in the State of Maine, where Professor George H. Stone
has plotted them with much care. The accompanying
map gives only an imperfect representation of the ramify-
ing systems which he has traced out, and of the extent to
which they are independent of the present river-channels.
One of the longest of these extends more than one hun-
dred miles, crossing the Penobscot River nearly opposite
Grand Lake, and terminating in an extensive delta of
gravel and sand in Cherryfield, nearly north of Mount
Desert. This is represented on our map by the shaded
portion west of the Machias River. Locally these ridges
are variously designated as “ horsebacks,” ‘“ hogbacks,” or
“ whalebacks,” but that in Andover, Mass., was for some
reason called “ Indian Ridge.” Nowhere else in the world

ANCIENT GLACIERS. 81

are these ridges better developed than in New England,
except it be in southern Sweden, where they have long
been known and carefully mapped.

SCALE OF MILES
20 40 60
Struthers §& Co., Engr’s, N.Y.

Fig. 32.—The kames of Maine and southeastern New Hampshire. (Stone.)

The investigations of Mr. W. O. Crosby upon the com-
position of till in eastern Massachusetts is sufficiently im-

ee ie
4

82 MAN AND THE GLACIAL PERIOD.

portant in its bearings upon the question of glacial erosion
to merit notice at this point.* The object of his investi-
gations was to determine how much of the so-called
ground moraine, or till, consisted of material disintegrated
by mechanical action, and how much by chemical action.
The “ residuary clay,” which has arisen from chemical de-
composition, would properly be attributed to the disinte-
grating agencies of preglacial times, while the clay, which
is strictly mechanical in its origin, remains to represent
the true “ grist” or “rock flour” of the Glacial period.

The results of Mr. Crosby’s investigations show that
“not more than one-third of the detritws con:posing the
till of the Boston Basin was in existence before the Ice
age, and that the remaining two-thirds must be attributed
to the mechanical action of the ice-sheet and its accom-
panying torrents of water. In other words, if we assume
the average thickness of the drift as thirty feet, the
amount of glacial erosion can scarcely fall below twenty
feet. After scraping away the residuary clays and half-
decomposed material, the ice-sheet has cut more than an
equal depth into the solid rocks.”

Mr. Crosby’s investigations also convinced him that the
movement of the till, or ground moraine, underneath the ice
was not en masse, but that “it must have experienced dif-
ferential horizontal movements or flowing, in which, nor-
mally, every particle or fragment slipped or was squeezed
forward with reference to those immediately below it, the
velocity diminishing downward through the friction of
the underlying ledges, . . . The glaciation was not limited
to masses which were firmly caught between the ice and
the solid ledges, and it was in every case essentially a slip-
ping and not a rolling movement. . . . These differential
horizontal movements mean that the till acted as a Iubri-

* Proceedings of the Boston Society of Natural History, vol.
xxv (1890), pp. 115-140.

ANCIENT GLACIERS. 83
cant for the ice-sheet; and the clayey element, especially,
co-operating in many cases with the pent-up subglacial
waters, must have greatly facilitated the onward progress
of the ice.’ He concludes, therefore, that the onward
movement of the vast ice-sheet greatly exceeded that of
the main part of the ground moraine, the ice-sheet slipping
over the till, the whole being in some degree analogous to
that of a great land-slip. “In both cases the progress of
a somewhat yielding and mobile mass is facilitated by an
underlying clayey layer saturated with water.”

New York, New Jersey, and Pennsylvania,

West of New England the glacial phenomena over the
northern part of the United States are equally marked all
the way to the Missouri River, and the boundary-line of
the glaciated region can be traced with little difficulty.
It emerges from New York Bay on Staten Island and
enters New Jersey at Perth Amboy. A well-formed
moraine covers the northern part of Staten Island, and
upon the mainland marks the boundary from Perth
Amboy, around through Raritan, Plainfield, Chatham,
Morris, and Hanover, to Rockaway, and thence in a
southwesterly direction to Belvidere, on the Delaware
River. That portion of New Jersey lying north of this
serpentine line of moraine hills is characterised by the
presence of transported boulders, by numerous lakes of
evident glacial origin, and by every other sign of glacial
action, while south of it all these peculiar characteristics
are absent. The observant passenger upon the railroad
trains between New York and Philadelphia can easily
recognise the moraine as it is passed through on the
Pennsylvania Railroad at Metuchen and on the Bound
Brook Railroad at Plainfield: Near Drakestown, in Mor-
ris County, there is a mass of blue limestone measuring,
as exposed, thirty-six by thirty feet, and which was quar-
ried for years before discovering that it was a boulder

S4 MAN AND THE GLACIAL PERIOD.

brought with other drift material from many miles to the
northwest and lodged here a thousand feet above the sea.

Across Pennsylvania the glacial boundary passes
through Northampton, Monroe, Luzerne, Columbia, Sul-
livan, Lycoming, Tioga, and Potter Counties, where it en-
ters the State of New York, running still in a northwest
direction through Allegany and Cattaraugus Counties to
the vicinity of Salamanca. Here it turns to the south
nearly at a right angle, running southwestward to Chau-
tauqua County and re-entering Pennsylvania in Warren
County, and thence passing onward in the same general
direction through Crawford, Venango, Mercer, Butler,
and Lawrence Counties to the Ohio line in Columbiana
County, about ten miles north of the Ohio River.

The occurrence of a well-defined terminal moraine to
mark the glacial boundary eastward from Pennsylvania
led Professor Lewis and myself, who made the survey of
that State in 1880, to be rather too sanguine in our ex-
pectations of finding an equally well-marked moraine
everywhere along the southern margin of the glaciated
area; still, the results are even more interesting than
would have been the exact fulfilment of our expectations,
since they more fully revealed to us the great complexity
of effect which is capable of being brought about by ice-
action. Before proceeding farther with the details, there-
fore, it will be profitable at this point to pause in the
narrative and briefly record a few generalisations that have
forced themselves into prominence during the years in
which field-work has been in progress.

Previous to our explorations in Pennsylvania it had
been thought that the indications of ice-action would
extend much farther south in the valleys than on the
mountains, and this indeed would have been the case if
the glaciers in northern Pennsylvania had been of local
origin; but our experience very soon demonstrated that
the great gathering-place of the snows which produced

“

ANCIENT GLACIERS. 85

the glacial movement in northern Pennsylvania could not
have been local, but that over the northern part of that
State there was distinct evidence of a continental move-
ment of ice whose centre was far beyond the Allegha-
nies. ;

For example, we found that the evidences of direct
glacial action extended farther south upon the hills and
plateaus than they did in the narrow valleys, while every-
where on the very southern border of glacial indications
we found boulders that had been brought from the gra-
nitic region of northern New York or central Canada.
In eastern Pennsylvania we found indeed a terminal mo-
raine more or less distinctly marking the southern border
over the highlands. ‘This was more specially true in
Northampton and Monroe Counties.

In Northampton County it was very interesting to see
long lines of hills, a hundred or more feet in height and
lying several hundred feet above the Delaware River, com-
posed entirely of glacial débris, much of which had been
brought bodily over the sharp summit of the Blue Ridge,
or Kittatinny Mountain, which rises as a continuous wall
to the northwest and is everywhere several hundred feet
higher than the moraine in Northampton County. ‘The
summit of Blue Ridge, also, as far south as the glacial
movement extended, shows evident signs of glacial abra-
sion, some hundreds of feet evidently having been removed
by that means, leaving a well-defined shoulder, marking
the limits of its southwestern border. Resting upon the
summit of the glaciated portion of the Blue Ridge, there
are alsonumerous boulders of Helderberg limestone, which
must have been brought from ledges at least five hundred
feet lower than the places upon which they now lie.

In Monroe County the terminal moraine marking there
the extreme limit of the ice-movement is upon an exten-
sive plateau of Pocono sandstone, about eighteen hundred
feet above sea-level, and five or six hundred feet lower than

86 MAN AND THE GLACIAL PERIOD.

the crest of the Alleghany Mountains, a short distance to
the north. The moraine hills are here well marked by
the occurrence of circular lakelets and kettle-holes (such
as have been described as characteristic of the shores and
islands bordering the south of New England); by the
occurrence of granitic boulders, which must have been
brought from the Adirondacks or Canada; and by the
various other indications referred to on a previous page.

As already intimated, the instructive point in our ob-
servations is the fact that, between Kittatinny Mountain,
in Northampton County, and Pocono plateau, in Monroe
County, there is a longitudinal depression, running north-
east by southwest, parallel with the ranges of the moun-
tain system, which is here about a thousand feet below the
respective ridges on either side. This, therefore, is one of
the places where we should have expected a considerable
southern extension of the ice, if it had been largely due to
local causes. Now, while there is indeed a gradual south-
ern trend down the flanks of the mountain, yet, upon reach-
ing the axis of the valley, there appears at once a very
marked change in the character of the deposit, and the
influence of powerful streams of water becomes manifest,
and it is evident, upon a slight inspection, that we have
come upon a line of drainage which sustained a peculiar
relation to the continental ice-sheet.

From Stroudsburg, near the Delaware Water-Gap, to
Weissport, on the Lehigh River, a distance of about thirty
miles, the valley between the mountains is continuous, and
the elevation at each end very nearly the same. But about
half-way between the two places, near Saylorsburg, there
is a river-parting from which the water now runs on the
one hand north to Stroudsburg, and thence to the Dela-
ware River, and on the other hand south, through Big and
Aquonchichola Creeks, to the Lehigh River. The river-
parting is formed bya great accumulation of gravel, whose
summit is about two hundred feet above the level of the

ANCIENT GLACHERS. 87

valleys into which the creeks empty at either end; and
there are numerous kettle-holes and lakelets in the vicini-
ty, such as characterize the glacial region in general.

In short, we are, without doubt, here on a well-marked
terminal moraine much modified by strong water-action
in a valley of glacial drainage. ‘The gravel and boulders
are all well water-worn, and the material is of various kinds,
including granite boulders from the far north, such as char-
acterise the terminal moraine on the highlands; but the
pebbles are not scratched, and the gravel is more or less
stratified. It is evident that we are here where a violent
stream of water poured forth from that portion of the ice-
front which filled this valley, and which found its only out-
let in the direction of the Lehigh River. ‘The gravel can
be traced in diminishing quantities to the southward, in
accordance with this theory, while to the northward there
extends a series of gravel ridges, or kames, such as we have
shown naturally to owe their origin to the accumulations
taking place in ice-channels formed near the front of a
glacier as it slowly melts away.

From similar occurrences of vast gravel accumulations
in other valleys stretching southward from the glacial
margin, we came to expect that, wherever there was an
open. line of drainage from the glaciated region south-
ward, the point of intersection between the glacial margin
and the drainage valley would be marked by an excessive
accumulation of water-worn gravel, diminishing in coarse-
ness and abundance down the valleys in proportion to the
distance from the glacial margin.

For example, the Delaware River emerges from the
glaciated region at Belvidere, and there are there vast ac-
cumulations of gravel rising a hundred or more feet above
the present level of the river, while gravel terraces, dimin-
ishing in height, mark the river below to tide-water at
Trenton. The Lehigh River leaves the glaciated region
at Hickory Run, a few miles above Mauch Chunk, but

88 MAN AND THE GLACIAL PERIOD.

the gorge is so steep that there was little opportunity
either for the accumulation of gravel there or for its preser-
vation. Still, the transported gravel and boulders charac-
teristic of the melting floods pouring forth from a glacier,
are found lining the banks of the Lehigh all along the
lower portion of its course. In the Susquehanna River
we have a better example at Beach Haven, in Luzerne —
County, where there are very extensive accumulations of
gravel resting on the true glacial deposits of the valley,
and extending down the river in terraces of regularly
diminishing height for many miles, and merging into ter-
races of moderate elevation which line the Susquehanna
Valley throughout the rest of its course. Above Beach
Haven the gravel deposits in the trough of the river valley
are more irregular, and betray the modifying influence of
the slowly decaying masses of ice which belonged to the
enveloping continental glacier.

Westward from the north fork of the Susquehanna,
similar extensive accumulations of gravel occur at the in-
tersection of Fishing Creek in Columbia County, Muncy,
Loyalsock, Lycoming, and Pine Creeks in Lycoming
County, all tributary to the Susquehanna River, and all
evidently being channels through which the melting floods
of the ice-sheet brought vast quantities of gravel down to
the main stream. Williamsport, on the West Branch of
the Susquehanna, is built upon an extensive terrace con-
taining much granitic material, brought down from the
glaciated region by Lycoming Creek, when it was flooded
with the waters melted from the continental ice-sheet
which had here surmounted the Alleghanies and invaded
the valley of the Susquehanna.

Analogous deposits of unusual amounts of gravel, oc-
curring in streams flowing southward from the glaciated
region, occur at Great Valley, Little Valley, and Steam-
burg in Cattaraugus County, New York, and at Russel-
burg and Garland in Warren County, Pennsylvania, also

ANCIENT GLACEERS. 89

at Titusville and Franklin in Venango County, and at
Wampum in Lawrence County, of the same State.

Asarule, Professor Lewis and myself found it more
difficult to determine with accuracy the exact point to
which the ice extended in the axis of these south-flowing
valleys than we did upon the highlands upon either side;
and, in looking for the positive indications of direct ice-
action in these lines of drainage, we were almost always
led up the valley to a considerable distance inside of the
line. This arose from our inexperience in interpreting
the phenomena, or rather from our inattention to the
well-known determining facts in the problem. On fur-
ther reflection it readily appeared that this was as it should
be. The ice-front, instead of extending farther down in
a narrow valley than on the adjoining highlands (where
they are of only moderate elevation) ought not to extend
so far, for the subglacial streams would not only wear
away the ice of themselves, but would admit the air into
the tunnels formed by them so as to melt the masses both
from below and from above, and thus cause a recession of
the front. If we had understood this principle at the be-
ginning of our survey, it would have saved us much per-
plexity and trouble.

A single further illustration of this point will help to
an understanding of many references which will hereafter
be made to the water deposits which accumulated in the
lines of drainage running southward from the glaciated
area. At Warren, Pa., Conewango Creek, which is the
outlet from Chautauqua Lake, enters the Alleghany River
after flowing for a number of miles in a deep valley with
moderate slopes. In ascending the creek from Warren,
the gravel terraces, which rise twenty-five or thirty feet
above high-water mark, rapidly increase in breadth and
height, and the pebbles become more and more coarse.
After a certain distance the regular terraces begin to give
place to irregular accumulations of gravel in ridges and

90 MAN AND THE GLACIAL PERIOD.

knobs. In the lower portion of the valley no pebbles
could be found which were scratched. Up the valley
a few miles pebbles were occasionally discovered which
showed some slight indications of having been scratched,
but which had been subjected to such an amount of abra-
sion by water-action as almost to erase the scratches. On
reaching Ackley’s Station, the stream is found to be cut-
ting through a regular terminal moraine, extending across
the valley and full of clearly marked glaciated stones.
Above this terminal moraine the terraces and gravel
ridges which had characterised the valley below disappear,
giving place to long stretches of level and swampy land,
which had been subject to overflow.

Something similar to this so often appears, that there
can be no question as to its meaning, which is, that dur-
ing the farthest extent of the ice the front rested for a
considerable period of time along the line marked by the
terminal moraine. During this period there occurred both
the accumulation of the moraine and of the gravel terraces
in the valley below, due to the vast flow of water emerg-
ing from the ice-front, especially during the period when
it was most rapidly melting away. Upon the retreat of
the ice, the moraine constituted a dam which has not yet
been wholly worn away. For a while the water was so ef-
fectually ponded back by this as to form a lake, which has
since become filled up with sediment and accumulations
of peat. From this it is evident, also, that when the ice
began to retreat, the retreat was so continuous and-rapid
that no parallel terminal moraines were formed for many
miles.

Before leaving this section we will summarise the
leading facts concerning the glacial phenomena north of
Pennsylvania and New Jersey. From the observations of
Professor Smock, it appears that, from the southern mar-
gin the ascent to the summit of the ice-sheet was pretty
rapid; the depth one mile back from the margin being

ANCIENT GLACIERS. 91

—

not much less than a thousand feet. “ Northward the
angle of the slope diminished, and the glacier surface ap-
proximated to a great level plain. The distance between
the high southwestern peaks of the Catskills and Pocono
Knob in Pennsylvania is sixty miles. ‘The difference in
the elevation of the glacier could not have exceeded a
thousand feet,” * that is, the slope of the surface was
about seventeen feet to the mile.

Professor Dana estimates the thickness of the ice in
southern Connecticut to have been between fifteen hun-
dred and two thousand feet. Attempts to calculate the
thickness of the ice farther north, except from actual dis-
covery of glacial action on the summits of the mountains,
are based upon uncertain data with reference to the slope
necessary to secure glacial movement. In the Alps the
lowest mean slopes down which glaciers move are about
two hundred and fifty feet to a mile; but in Greenland,
Jensen found the slope of the Frederickshaab Glacier to
be only seventy-five feet to the mile, while Helland found
that of the Jakobshavn Glacier to be only forty-five feet.

It is doubtful if even that amount is necessary to se-
cure a continental movement of ice, since, as already re-
marked, it is unsafe to draw inferences concerning the
movements of large masses of ice from those of smaller
masses in more constricted areas. We have seen, from
the glacial deposits on the top of Mount Washington,
that over the northern part of New England the ice was
more than a mile in depth. We have no direct evidence
of the depth of the stream which surrounded the Adiron-
dack Mountains. Nor, on the other hand, are we certain
that the Catskills were not completely enveloped in ice,
though most observers, reasoning from negative evidence,
have supposed that to be the case. But from the facts
stated concerning the boulders along the glacial boundary

* American Journal of Science, vol. cxxv, 1883, p. 339 e¢ seq.

ge ee

99 MAN AND THE GLACIAL PERIOD.

>

in Pennsylvania, it is certain that the ice was deep enough
to surmount the ridge of the Alleghanies where they are
two thousand and more feet in height. At the least cal-
culation the ice must have been five hundred feet thick,
in order to secure the movement of which there is eyi-
dence across the Appalachian range. Supposing this to
be the height of the ice above the sea on the crest of the
Alleghanies, and that the slope of the surface of the ice-
sheet was as moderate as Professor Smock has estimated
it (namely seventeen feet to the mile), the ice would be
upwards of six thousand feet in thickness in the latitude
of the Adirondacks, which corresponds closely with the
positive evidence we have from the mountains in New
England.

A study of the map of New York will make it easy to
understand the distribution of some interesting glacial
marks over the State. The distance along the Hudson
from the glacial boundary in the vicinity of New York to
the valley of the Mohawk is about one hundred and sixty
miles. From the glacial boundary at Salamanca, N. Y.,
to the same valley, is not over eighty miles. It is easy to
see, therefore, that when, in advancing, the ice moved
southward past the Adirondacks, the east end of the valley
of the Mohawk was reached and closed by the ice, while
at the west end of Lake Ontario the ice-front was still in
Canada. Thus the drainage, which naturally followed
the course of the St. Lawrence, would first be turned
through the Mohawk. Afterwards, when the Mohawk
had been closed by ice, the vast amount of ponded water
was compelled to seek a temporary outlet over the lower
passages leading into the Susquehanna or into the Alle-
ghany. ;

A number of such passages exist. One can be traced
along the line of the old canal from Utica to Bingham-
ton, whose highest level is not far from eleven hundred
feet. Another lies in a valley leading south of Cayuga

ANCIENT GLACIERS. 93

Lake, whose highest point, at Wilseyville, is nine hundred
and forty feet above tide. Another leads south to the
Chemung River from Seneca Lake, whose highest point,
at Horseheads, is less than nine hundred feet above tide.
The cols farther west are somewhat more elevated; the
one at Portage, leading from the Genesee River into the
Canisteo, being upwards of thirteen hundred feet, and
that of Dayton, leading from Cattaraugus Creek into the
Conewango, being about the same. Of other southern
outlets farther west we will speak later on.

Fixing our minds now upon the region under consid-
eration, in the southern part of the State of New York,
we can readily see that a glacial lake must have existed in
front of the ice while it was advancing, until it had reached
the river-partings between the Mohawk and the St. Law-
rence Rivers on the north and the Susquehanna and Alle-
ghany Rivers on the south. After the ice had attained its
maximum extension, and was in process of retreat, there
would be a repetition of the phenomena, only they would
occur in the reverse order. The glacial markings which
we see are, of course, mainly those produced during the
general retreat of the ice.

The Susquehanna River stretching out its arms—the
Chenango and Chemung Rivers—to the east and the west,
evidently serves as a line of drainage for the vast glacial
floods. These floods have left, along their courses, extensive
elevated gravel terraces, with much material in them which
is not local, but which has been washed out of the direct
glacial deposits from the far north. The east-and-west
line of the water-parting throughout the State is charac-
terised by excessive accumulations of glaciated material,
forming something like a terminal moraine, and is desig-
nated by President Chamberlin as “ the terminal moraine
of the second Glacial epoch,” corresponding, as he thinks,
to the interior line already described as characterising the
south shore of New England,

In the central part of New York the remarkable se-
ries of “ Finger Lakes,” tributary to Lake Ontario and
emptying into it through the Oswego and Genesee Rivers,
all have a glacial origin. Probably, however, they are not
due in any great degree to glacial erosion, but they seem
to occupy north-and-south valleys which had been largely
formed by streams running towards the St. Lawrence
when there was, by some means (probably through the
Mohawk River), a much deeper outlet than now exists,
but which has been filled up and obliterated by glacial
débris. ‘The ice-movement naturally centred itself more
or less in these north-and-south valleys, and hence some-
what enlarged them, but probably did not deepen them.
The ice, however, did prevent them from becoming filled
with sediment, and on its final retreat gave place to
water.

Between these lakes and Lake Ontario, also, and ex-
tending east and west nearly all the way from Syracuse to
Rochester, there is a remarkable series of hills, from one
hundred to two or three hundred feet in height, composed
of glacial débris. But while the range extends east and
west, the axis of the individual hills les nearly north and
south. These are probably remnants of a morainic ac-
cumulation which were made during a pause in the first
advance of the ice, and were finally sculptured into their
present shape by the onward movement of the ice. These
are really “ drumlins,” similar to those already described
in northeastern Massachusetts and southeastern New
Hampshire. In the valley of central New York these
have determined the lines of drainage of the “ Finger
Lakes,” and formed dams across the natural outlets of
nearly all of them. |

North of the State of New York the innumerable
lakes in Canada are all of glacial origin, being mostly due
to depressions of the nature of kettle-holes, or to the dam-
ming up of old outlets by glacial deposits. A pretty well-

94 MAN AND THE GLACIAL PERIOD.

ANCIENT GLACIERS. 95

a

marked line of moraine hills, formed probably as termi-
nal deposits in the later stages of the Ice age, runs from
near the eastern end of Lake Ontario to the Georgian
Bay, passing south of Lake Simcoe.

The Mississippi Basin.

The physical geography of the glaciated region north
of the Ohio River is so much simpler than that of New
England and the Middle States, that its characteristics
can be briefly stated. Ohio, Indiana, and Illinois are coy-
ered with nearly parallel strata of rock mostly of the Car-
boniferous age. In general, the surface slopes gently to
the west; the average elevation of Ohio being about a
thousand feet above tide, while that of the Great Lakes to
the north and of the middle portion of the Mississippi
Valley is less than six hundred feet. The glacial deposits
are spread in a pretty even sheet over the area which was
reached by the ice in these States, and the lines of mo-
raine, of which a dozen or more have been partially traced
in receding order, are much less clearly marked than they
are in New England, or in Michigan, and the States far-
ther to the northwest.

The line marking the southern limit attained by the
ice of the Glacial period in these three States is as follows:
Entering Ohio in Columbiana County, about ten miles
north of the Ohio River, the glacial boundary runs west-
ward through New Lisbon to Canton in Stark County,
and thence to Millersburg in Holmes County. A few
miles west of this place it turns abruptly south, passing
through Danville in Knox County, Newark in Licking
County, Lancaster in Fairfield County, to Adelphi in Ross
County. Thence bearing more westward it passes through
Chillicothe to southeastern Highland County and north-
western Adams, reaching the Ohio River near Ripley, in
Clermont County. Thence, following the north bank of

the Ohio River to Cincinnati, it crosses the river, and after
8

96 MAN AND THE GLACIAL PERIOD.

extending through the northern part of Boone County,
Kentucky, and recrossing the river to Indiana, not far
from Rising Sun, it again follows approximately the north
bank of the river to within about ten miles of Louisville,
Ky., where it bends northward running through Clarke,
Scott, Jackson, Bartholomew, and Brown Counties to Mar-
tinsville, in Morgan County, where it turns again west and
south and follows approximately the West Branch of the
White River through Owen, Greene, and Knox Counties,
where it crosses the main stream of White River, and, con-
tinuing through Gibson and Posey Counties, crosses the
Wabash River near New Harmony.

In Illinois the line still continues southwesterly through
White, Gallatin, Saline, and Williamson Counties, where
it reaches its southern limit near Carbondale, in latitude
37° 40’, and from this point trends northwestward, ap-
proximately following the northeastern bluff of the Mis-
sissippl River, to the vicinity of Carondelet, Mo., a short
distance south of St. Louis.

Beyond the Mississippi the line follows approximately
the course of the Missouri River across Missouri, and con-
tinues westward to the vicinity of Manhattan, in Kansas,
where it turns northward, keeping about a hundred miles
west of the Missouri River, through eastern Kansas and
Nebraska, and striking the river near the mouth of the
Niobrara, in South Dakota. From there the line follows
approximately the course of the Missouri River to the vicin-
ity of Fort Benton, in northwestern Montana, where the line
again bears more northward, running into British America.

It is still in dispute whether the ice extended from the
eastern centre far enough west to join the ice-movement
from the Rocky Mountain plateau. Dr. George M. Daw-
son * is of the opinion that it did not, but that there was

* Transactions of the Royal Society of Canada, vol. viii, sec. iv,
pp. 04-74,

ANCIENT GLACIERS. 97

a belt of ahundred miles or more, east of the Rocky Moun-
tains, which was never covered by true glacial ice. Mr.
Upham * is equally confident that the two ice-movements
became confluent, and united upon the western plateau of
Manitoba. The opportunity for such a difference of opin-
ion arises in the difficulty sometimes encountered of dis-
tinguishing between a direct glacial deposit and a deposit
taking place in water containing boulder-laden icebergs.
Where Mr. Upham supposes the ice-fields of the east and
of the west to have been confluent in western Manitoba,
Dr. Dawson supposes there was an extensive subsidence of
the land sufficient to admit the waters of the ocean. Leay-
ing this question for the present undetermined, we will
now rapidly summarise the glacial phenomena west of the
third meridian from Washington (which corresponds near-
ly with the western boundary of Pennsylvania), and east of
the Rocky Mountains.

That the glacial movement extended to the southern
boundary just delineated is established by the presence
down to that line of all the signs of glacial action, and
their absence beyond. Glacial groovings are found upon
the freshly uncovered rock surfaces at frequent intervals
in close proximity to the line all along its course, while
granitic boulders from the far north are scattered, with
more or less regularity, over the whole intervening space
between this line and the Canadian highlands. I have
already referred to a boulder of jasper conglomerate found
in Boone County, Kentucky, which must have come from
unique outcroppings of this rock north of Lake Huron.
Granitic boulders from the Lake Superior region are also
found in great abundance at the extreme margin men-
tioned in southern Ilinois. West of the Missouri River
it is somewhat more difficult to delineate the boundary

—

* American Geologist, vol. vi, September, 1890; Bulletin of the
Geological Society of America, vol. ii, pp. 243-276,

98 MAN AND THE GLACIAL PERIOD.

with accuracy, on account of an enveloping deposit of fine
loam, technically called “ loess.” Loess is very abundant
in the whole valley of the Missouri River below Yankton,
South Dakota, being for a long distance in the vicinity of
the river a hundred feet or more in depth. Over north-
ern Missouri and southern Illinois the deposit is nearly
continuous, but less in depth, and everywhere in that re-
gion tends to hide from view the unstratified glacial de-
posit continuously underlying it.

A single instance of personal experience will illustrate
the condition of things. While going south from Chicago,
in search of the southern limit of glacial action, I stopped
off from the train at Du Quoin, about forty miles north
of where I subsequently found the boundary. Here the
whole surface was covered with loess, two or three feet in
depth. Below this was a gravelly soil, three or four feet
in thickness, which contained many scratched pebbles of
granite. A well which had recently been dug, reached
the rock at a depth of twenty feet, and revealed a beauti-
fully polished and scratched surface, betraying, beyond
question, the action of glacial ice. As we shall show a
little later, it is probable that, about the time the ice of
the Glacial period had reached its maximum development,
this area, which is covered with loess, was depressed in
level, and remained under water during a considerable
portion of the period when the ice-front was retreating.

To such an extent is this portion of the area included
in southern Iowa, northern Missouri, southern Illinois,
and the extreme southern portions of Indiana and Ohio
covered with loess, that it has been difficult to determine
the relation of its underlying glacial deposits to the more
irregular deposits found farther north. At an early period
of recent investigations, while making a geological survey
of the State of Wisconsin, President T. C. Chamberlin
fixed upon the line of moraine hills, which can be seen
upon our map, running southward between Green Bay

Wis

== ————

ttle-moraine, near Eagle, Waukesha County, Wisconsin.

(From photograph by President T, C. Chamberlin, United States Geological Survey.)

33.—Western face of the ke

Fig.

100 MAN AND THE GLACIAL PERIOD.

and Lake Michigan, and sweeping around in a curve to the
right, passing south of Madison and northward along the
line of Wisconsin River, and in another curve to the left,
around the southern end of Lake Michigan, as the “ ter-
minal moraine of the second Glacial epoch.” In Wiscon-
sin the character of this line of moraine hills had been
discovered and described by Colonel Charles Whittlesey, in
1866. It was first named the “ kettle-moraine,” because
of the frequent occurrence in it of “ kettle-holes.” This
line of moraine hills has been traced with a great degree
of confidence across the entire glaciated area, as shown
upon our map, but it is not everywhere equally distinct,
and, as will be observed, follows a very irregular course.

Beginning in Ohio we find it coinciding nearly with
the extreme glacial boundary until it reaches the valley of
the Scioto River, on the sixth meridian west from Wash-
ington, where it begins to bear northward and continues
in that direction for a distance of sixty or seventy miles,
and then turns southward again in the valley of the
Miami, having formed between these two valleys a sort of
medial moraine.* A similar medial moraine had also been
noted by President Chamberlin between the valleys of the
Grand and Cuyahoga Rivers, in the eastern part of Ohio.
Indeed, for the whole distance across Ohio and Indiana,
this moraine occurs in a series of loops pointing to the
south, corresponding in general to the five gentle valleys
which mark the territory, namely, those of the Grand and
Mahoning Rivers; the Sandusky and Scioto Rivers; the
Great Miami River; the White River; and the Maumee
and Wabash Rivers. Everywhere, however, over this area
these morainic accumulations approximate pretty closely
to the extreme boundary of the glaciated region.

In Illinois President Chamberlin’s original determina-
tion of the moraine fixed it near the southern end of Lake

* See map at the beginning of the chapter.

ANCIENT GLACIERS. 101

Michigan, as shown upon our map, but Mr. Frank Leverett
has subsequently demonstrated that there is a concentric
series of moraines south of this, reaching across the State,
(but somewhat obscured by superficial accumulations of
loess referred to) and extending nearly to the latitude of
St. Louis.

West of Wisconsin President Chamberlin’s “ terminal
moraine of the second Glacial epoch” bends southward
through eastern Minnesota, and, sweeping down through
central Iowa, forms, near the middle of the northern part
of that State, a loop, having its southern extremity in the
vicinity of Des Moines. ‘The western arm of this loop runs
through Minnesota in a northwesterly direction nearly
parallel with the upper portion of the valley of the Minne-
sota, until reaching the latitude of the head-waters of that
river, where, in the vicinity of the Sisseton Agency, in
Dakota, it turns to the south by an acute angle, and makes
a loop in that State, extending to the vicinity of Yankton,
and with the valley of the James River as its axis. The
western arm of this loop follows pretty closely the line of
the eastern edge of the trough of the Missouri River, con-
stituting what is called the “ Missouri Coteau,” which
continues on as a well-marked line of hills running in
a northwesterly direction far up into the Dominion of
Canada.

One of the most puzzling glacial phenomena in the
Mississippi Valley is the driftless area which occupies the
southeastern portion of Minnesota, the southwestern part
of Wisconsin, and the northwestern corner of Iowa, as de-
lineated upon our map. This is an area which, while being
surrounded on every side by all the characteristic marks of
glaciation, is itself conspicuous for their entire absence.
Its rocks preserve no glacial scratches and are covered by
no deposits of till, while northern boulders avoided it ir.
their journey to more southern latitudes.

The reason for all this is not evident in the topography

102 MAN AND THE GLACIAL PERIOD.

of the region. The land is not higher than that to the
north of it, nor is there any manifest protection to it by
the highlands south of Lake Superior. Nor yet is there
any reason to suppose that any extensive changes of level
in former times seriously affected its relations to the sur-
rounding country. Professor Dana, however, has called
attention to the fact that even now it is in a region of
comparatively light precipitation, suggesting that the
snow-fall over it may always have been insignificant in
amount. But this could scarcely account for the failure
of the great ice-wave of the north to overrun it. Weare
indebted again to the sagacity of President Chamberlin in
suggesting the true explanation.

By referring to the map it will be noticed that this
area sustains a peculiar relation to the troughs of Lake
Michigan and Lake Superior, while from the arrange-
ments of the moraines in front of these lakes it will be seen
that these lake basins were prominent factors in determin-
ing the direction of the movement of the surplus ice from
the north. It is the more natural that they should do so
because of their great depth, their bottoms being in both
cases several hundred feet below the present water-level,
reaching even below the level of the sea.

These broad, deep channels seem to have furnished the
readiest outlet for the surplus ice of the North, and so to
have carried both currents of ice beyond this driftless area
before they became again confluent. The slight elevation
south of Lake Superior served to protect the area on ac-
count of the feebleness of direct movement made possible
by the strength of these diverging lateral ice-currents.
The phenomenon is almost exactly what occurs where a
slight obstruction in a river causes an eddy and preserves
a low portion of land below it from submergence. A
glance at the map will make it easily credible that an ice-
movement south of Manitoba, becoming confluent with
one from Lake Superior, pushed far down into the Mis-

ANCIENT GLACTERS. 103

souri Valley and spread eastward to the Mississippi River,
south of the unglaciated driftless area, and there became
confluent with a similar movement which had been di-
rected by the valleys of Lake Michigan and Lake Erie.
There can be little doubt that President Chamberlin’s ex-
planation is in the main correct, and we have in this an-
other illustration of the analogy between the behaviour of
moving ice and that of moving water.

Fie. 34.—Section of the east-and-west glacial furrows, on Kelly’s Island, pre-
served by Mr. Younglove, Fine sediment rests immediately on the rock,
with washed pebbles at the surface.

The accompanying illustrations will give a better idea
than words can do of the celebrated glacial grooves on the
hard limestone islands near Sandusky, in the western part

104 MAN AND THE GLACIAL PERIOD.

of Lake Erie. ‘Through the interest aroused in them by
an excursion of the American Association for the Ad-
vancement of Science, while meeting in Cleveland, Ohio,
in 1888, the Kelly Island Lime and ‘Transport Company,
of which Mr. M. C. Younglove is the president, has been
induced to deed to the Western Reserve Historical So-
ciety for preservation a portion of one of the most re-
markable of the grooves still remaining.

The portion of the groove preserved is thirty-three
feet across, and the depth of the cut in the rock is seven-
teen feet below the line, extending from rim to rim.
Originally there was probably here a small depression
formed by preglacial water erosion, into which the ice
crowded the material, which became its graving-tool, and
so the rasping and polishing went on in increasing degree
until this enormous furrow is the result. The groove,
however, is by no means simple, but presents a series of
corrugations merging into each other by beautiful curves.
When exposed for a considerable length it will resemble
nothing else so much as a collection of prostrate Corin-
thian columns lying side by side on a concave surface.

The direction of these grooves is a little south of west,
corresponding to that of the axis of the lake. This is
nearly at right angles to the course of the ice-scratches on
the summit of the water-shed south of this, between the
lake and the Ohio River. The reason for this change of
direction can readily be seen by a little attention to the
physical geography. The highlands to the south of the
lake rise about seven hundred feet above it. When the
Ice period was at its climax and overran these highlands,
the ice took its natural course at right angles to the termi-
nal moraine and flowed southeast according to the direc-
tion indicated by the scratches on the summit; but when
the supply of ice was not sufficient to overrun the high-
lands, the obstruction in front turned the course and the
resultant was a motion towards Toledo and the Maumee

(aaotsuno xX "9 “W Jo soyn0D) ‘sSurpoooad oy] sv omM“g—"eg “OI

106 MAN AND THE GLACIAL PERIOD.

Valley, where in the vicinity of Fort Wayne an extensive
terminal moraine was formed.

The much-mooted question of a succession of glacial
epochs finds the most of its supporting facts in the por-
tion of the glaciated area lying west of Pennsylvania.
That there have been frequent oscillations of the glacial
front over this' area is certain. But it is a question
whether the glacial deposits south of this distinct line of
moraine hills are so different from those to the north of
it as to necessitate the supposition of two entirely distinct
glacial epochs. This can be considered most profitably
here.

The following are among the points with reference to
which the phenomena south of the moraine just deline-
ated differ from those north of the hne:

1. The glacial deposits to the south appear to be dis-
tributed more uniformly than those to the north. ‘To the
north the drift is often accumulated in hills, and is dotted
over with kettle-holes, while to the south these are pretty
generally absent. Any one travelling upon a line of rail-
road which traverses these two portions of the glaciated
area as indicated upon our map can easily verify these
statements.

2. The amount of glacial erosion seems to be much
less south of the lne of moraine hills delineated than
north of them. Still, glacial striw are found, almost every-
where, close down to the extreme margin of the glaciated
area.

3. The gravel deposits connected with the drainage of
the Glacial period are much less abundant south of the
so-called “ terminal moraine of the second Glacial period ”
than they are north of it. South of this moraine the
water deposits attributed to the Glacial period are of such
fine silt as to indicate slow-moving currents over a gentle
low slope of the surface.

4. The glacial deposits to the south are more deeply

ANCIENT GLACIERS. 107

coloured than those to the north, showing that they have
been longer exposed to oxidising agencies. Even the
granitic boulders show the marks of greater age south of
this line, being disintegrated to a greater extent than
those to the north.

5. And, finally, there occur, over a wide belt bordering
the so-called moraine hills of the second Glacial epoch,
extensive intercalated beds of vegetal deposits. Among
the earliest of these to be discovered were those of Mont-
gomery County, Ohio, where, in 1870, Professor Orton, of
the Ohio Survey, found at Germantown a deposit of peat
fourteen feet thick underneath ninety-five feet of till, and
there seem also to be glacial deposits underneath the peat
as well as over it. The upper portion of the peat contains
“much undecomposed sphagnous mosses, grasses, and
sedges, and both the peat and the clayey till above it”
contain many fragments of coniferous wood which can be
identified as red cedar (Juniperus Virginianus). In nu-
merous other places in that portion of Ohio fresh-appear-
ing logs, branches, and twigs of wood are found under-
neath the till, or mingled with it, much as boulders are.
Near Darrtown, in Butler County, Ohio, red cedar logs
were found under a covering of sixty-five feet of till, and
so fresh that the perfume of the wood is apparently as
strong as ever. Similar facts occur in several other coun-
ties in the glaciated area of southern Ohio and southern
Indiana. Professor Collett reports that all over south-
western Indiana peat, muck, rotted stumps, branches, and
leaves of trees are found from sixty to one hundred and
twenty feet below the surface, and that these accumula-
tions sometimes occur to a thickness of from two to
twenty feet.

Farther to the northwest similar phenomena occur.
Professor N. H. Winchell has described them most. par-
ticularly in Fillmore and Mower Counties, Minnesota,
from which they extend through a considerable portion of

108 MAN AND THE GLACIAL PERIOD.

Iowa. In the above counties of Minnesota a stratum of
peat from eighteen inches to six or eight feet in thickness,
with much wood, is pretty uniformly encountered in dig-

Fie. 36.—Section of till near Germantown, Ohio, overlying thick bed of peat.
The man in the picture stands upon a shelf of peat from which the till has
been eroded by the stream. The dark spot at the right hand of the picture,
just above the water, is an exposure of the peat. The thickness of the till is
ninety-five feet. The partial stratification spoken of in the text can be seen
about the middle of the picture. The furrows up and down had been made
by recent rains. (United States Geological Survey.) (Wright.)

ANCIENT GLACIERS. 109

ging wells, the depth varying from twenty to fifty feet.
This county is near the highest divide in the State of Min-
nesota, and from it “flow the sources of the streams to the
north, south, and east.” The wood encountered in this
stratum indicates the prevalence of coniferous trees, and
the peat mosses indicate a cool and moist climate.

Nor are intercalated vegetable deposits absent from the
vast region farther north over the area that drains into
Hudson Bay. At Barnesville, in Clay County, Minnesota,
which lies in the valley of the Red River of the North, and
also in Wilkin County in the same valley, tamarack wood
and sandy black mud containing many snail-shells have
been found from eight to twelve feet below a surface of
till; and Dr. Robert Bell reports the occurrence of limited
deposits of lignite between layers of till, far to the north-
west, in Canada, and even upon the southern part of Hud-
son Bay; while Mr. J. R. Tyrrell reports * many indica-
tions of successive periods of glaciation near the northern
end of the Duck Mountain. The most characteristic in-
dications which he had witnessed consisted of stratified
beds of silt, containing fresh-water shells, with fragments
of plants and fish similar to those living in the lakes of
the region at the present time.

Reviewing these facts with reference to their bearing
upon the point under consideration, we grant, at the out-
set, that they do indicate a successive retreat and re-
advance of the ice over extensive areas. This is specially
clear with respect to the vegetal deposits interstratified
with beds of glacial origin. But the question at issue
concerning the interpretation of these phenomena is, Do
they necessarily indicate absolutely distinct glacial epochs
separated by a period in which the ice had wholly disap-
peared from the glaciated area to the north? That they

* Bulletin of the Geological Society of America, vol. i, pp. 395-
410,

110 MAN AND THE GLACIAL PERIOD.

do, is maintained by President Chamberlin and many oth-
ers who have wide acquaintance with the facts. That
they do not certainly indicate a complete disappearance
of the ice during an extensive interglacial epoch, is capa-
ble, however, of being maintained, without forfeiting one’s
rights to the respect of his fellow-geologists. The oppo-
site theory is thus stated by Dr. Robert Bell: “ It appears
as if all the phenomena might be referred to one general
Glacial period, which was long continued, and conse-
quently accompanied by varying conditions of tempera-
ture, regional oscillations of the surface, and changes in
the distributions of sea and land, and in the currents in
the ocean. ‘These changes would necessarily give rise to
local variations in the climate, and might permit of vege-
tation for a time in regions which need not have been far
removed from extensive glaciers.” *

At my request, Professor J. HE. Todd, of Iowa, whose
acquaintance with the region is extensive, has kindly writ-
ten out for me his conclusions upon this subject, which I
am permitted to give in his own words:

“Tam not prepared to write as I would like concern-
ing the forest-beds and old soils. I will, however, offer
the following as a partial report. I have come to think
that there is considerable confusion on the subject. I be-
lieve there are five or six different things classed under
one head.

“1. Recent Muck and Soils.—The finest example I have
found in the whole Missouri Valley was twenty feet below
silt and clay, in a basin inside the outer moraine, near
Grand View, South Dakota. From my examination of
the reported old soil near Albia, Iowa, I think the most
rational way of reconciling the conflicting statements con-
cerning it is that it also belongs to this class.

* Bulletin of the Geological Society of America, vol. i, pp. 287-
S10:

ANCIENT GLACHERS. bs

2. Peat or Soil under Loess.—This does not signify
much if the loess was formed in a lake subject to oro-
graphic oscillations, or if, as I am coming to believe,
it is a fluviatile deposit of an oscillating river hke the
Hoang-Ho on the great Chinese plain. It at least does
not mean an interglacial epoch.

“3. Wood and Dirt rearranged, not in situ.—This
occurs either in subaqueous or in subglacial deposits. I
have found drift-wood in the lower layers of the loess
here, but not im situ. I have frequently found traces of
wood in till in Dakota, but always in an isolated way. I
think, from reading statements about the deposits in east-
ern Iowa, that most if not all of the cases are of this
sort. ‘'wo things have conspired to lead to this error:
one, the influence of Croll’s speculation; and the other,
the easy inference of many well-diggers, and especially
well-borers, that what they pass through are always in
layers. In this way a log becomes a forest-bed. Scat-
tered logs and muck fragments occurring frequently in a
region, though at different levels, are readily imagined by
an amateur geologist to be one continuous stratum ante-
dating the glacier or floods (as the case may be in that
particular region), when, in fact, it has been washed down
from the margin of the transporting agent and is con-
temporaneous with it. I suspect the prevalence of wood
in eastern Iowa may be traced to a depression of the
driftless region during the advance of the glacier, so as to
bring the western side of that area more into the grasp
of glacial agencies.

“4, Peat between Subglacial Tills.—If cases of this sort
are found, they are in Illinois, Indiana, and Ohio. Pro-
fessor Worthen insisted that there were no interglacial
soils or forest-beds in Illinois; and in the cases mentioned
in the State reports he repeatedly explains the sections
given by his assistants, so as to harmonize them with that

statement. I think he usually makes his explanations
9

ae MAN AND THE GLACIAL PERIOD.

plausible. He was very confident in referring most of
them to preglacial times, His views, I suppose, will be pub-

lished in the long-delayed volume, now about to be issued.

“5. Vegetable Matter between Glacial Till and Under-
lying Berg Till or other Drift Deposits.— W hen one remem-
bers that the front of the great ice-sheet may have been as
long in reaching its southern boundary as in receding
from it, and with as many advance and retrograde move-
ments, we can easily believe that much drift material
would have outrun the ice and have formed deposits so far
ahead of it that vegetation would have grown before the
ice arrived to bury it.

“6. Preglacial Soils, etc.—I believe that this oral be
found to include most in southern Ohio, if not in Illinois,
as Worthen claimed.”

The phenomena of the Glacial period are too vast
either to have appeared or to have disappeared suddenly.
By whatever cause the great accumulation of ice was pro-
duced, the advance to the southward must have been slow
and its disappearance must have been gradual, though, as
we shall show a little later, the final retreat of the ice-
front occupied but a short time relatively to the whole
period which has elapsed since. As we shall show also,
the advent of the Ice period was probably preceded and
accompanied by a considerable elevation of the northern
part of the continent. Whether this elevation was con-
temporaneous upon both sides of the continent is perhaps
an open question ; but with reference to the area east of the
Rocky Mountains, which is now under consideration, the

centre of elevation was somewhere south of Hudson Bay. ©

Putting together what we know, from the nature of the
case, concerning the accumulation and movement of gla-
cial ice, and what we know from the relics of the great
glacial invasion, which have enabled us to determine its
extent and the vigour of its action, the course of events
seems to have been about as follows:

ANCIENT GLACIERS. 113

Throughout the Tertiary period a warm climate had
prevailed over British America, Greenland, and indeed
over all the lands in proximity to the north pole, so far as
explorers have been able to penetrate them. ‘The vege-
tation characterizing these regions during the Tertiary
period indicates a temperature about lke that which now
prevails in North Carolina and Virginia. Whatever may
be said in support of the theory that the Glacial period
was produced by astronomical causes, in view of present
facts those causes cannot be regarded as predominant; at
most they were only co-operative. The predominant
cause of the Glacial period was probably a late Tertiary
or post-Tertiary elevation of the northern part of the
continents, accompanied with a subsidence in the cen-
tral portion. Of such a subsidence in the Isthmus of
Panama indications are thought to be afforded by the
occurrence of late Tertiary or, more probably, post-Terti-
ary sea-shells at a considerable elevation on the divide
along the Isthmus of Panama, between the Atlantic and
Pacific Oceans. Of this we shall speak more fully ina
later chapter.

Fixing our thoughts upon what is known as the Lau-
rentian plateau, which, though now in the neighbourhood
of but two thousand feet above the sea, was then much
higher, we can easily depict in imagination the begin-
nings of the great “ Laurentide Glacier,” which eventually
extended to the margin already delineated on the south
and southwest in the United States, and spread north-
ward and eastward over an undetermined area. Year
after year and century after century the accumulating
snows over this elevated region consolidated into glacial
ice and slowly pushed outward the surplus reservoirs of
cold. For a long time this process of ice-accumulation
may have been accompanied by the continued elevation
of the land, which, together with the natural effect of the
enlarging area of ice and snow, would tend to lower the

~

114 MAN AND THE GLACIAL PERIOD.

temperature around the margin and to increase still more
the central area of accumulation.

The vigour of movement in any direction was deter-
mined partly by the shape of the valleys opening south-
ward in which the ice-streams would naturally concen-
trate, and partly by those meteorological conditions which
determine the extent of snow-fall over the local centres
of glacial dispersion. Jor example, the general map of
North America in the Ice period indicates that there
were two marked subcentres of dispersion for the great
Laurentide Glacier, the eastern one being in Labrador
and the western one north of Lake Superior. In a
general way the southern boundary of the glaciated re-
gion in the United States presents the appearance of por-
tions of two circumferences of circles intersecting each
other near the eastern end of Lake Erie. These circles, I
am inclined to believe, represent the areas over which a
semi-fluid (or a substance like ice, which flows like a sem1-
fluid) would disperse itself from the subcentres above
mentioned.

A study of the contour of the country shows that that
also, in a general way, probably had something to do with
the lines of dispersion. The western lobe of this glaciated
area corresponds in its boundary pretty closely with the
Mississippi Valley, having the Ohio River approximately
as its eastern arm and the Missouri as its western, with
the Mississippi River nearly in its north and south axis.
The eastern lobe has its farthest extension in the axis of
the Champlain and Hudson River Valleys, its western
boundary being thrown more and more northward as the
line proceeds to the west over the Alleghany Mountains
until reaching the longitude of the eastern end of Lake
Erie; but this southern boundary is by no means a water-
level, nor is the contour of the country such that it could
ever have been a water-level. But it conforms in nearly
every particular to what would be the resultant arising

ANCIENT GLACIERS. 115

from a pretty general southward flow of a semi-fluid from
the two subcentres mentioned, meeting with the obstruc-
tions of the Adirondacks in northern New York and of
the broader Appalachian uplift in northern Pennsylvania.

How far south the area of glacial accumulation may
have extended cannot be definitely ascertained, but doubt-
less at an early period of the great Ice age the northern
portions of the Appalachian range in New York, New
England, New Brunswick, and Nova Scotia became them-
selves centres of dispersion, while only at the height of
the period did all their glaciers become confluent, so that
there was one continuous ice-sheet.

In the western portion of the area covered by the Lau-
rentide Glacier, the depression occupied by the Great
Lakes, especially Lakes Michigan and Superior, evidently
had a marked influence in directing the flow of ice during
the stages which were midway between the culmination
of the Ice period and both its beginning and its end.
This would follow from the great depth of these lakes,
the bottom of Lake Michigan being 286 feet below sea-
level, and that of Lake Superior 375 feet, making a total
depth of water of about 900 and 1,000 feet respectively.
Into these oblong depressions the ice would naturally
erayitate until they were filled, and they would become
the natural channels of subsequent movement in the di-
rection of their longest diameters, while the great thick-
ness of ice in them would make them the conservative
centres of glacial accumulation and action after the ice
had begun to retreat.

These deductions from the known nature of ice and
the known topography of the region are amply sustained
by a study of the detailed map showing the glacial geol-
ogy in the United States. But on this we can represent
indeed only the marks left by the ice at various stages of
its retreat, since, as already remarked, the marks of each
stage of earlier advance would be obliterated by later for-

116 MAN AND THE GLACIAL PERIOD.

ward movements. We may presume, however, that in
general the marks left by the retreating ice correspond
closely with those actually made and obliterated by the
advancing movement.

From observations upon the glaciers of Switzerland
and of Alaska, it is found that neither the advance nor
the retreat of these glaciers is constant, but that, in obe-
dience to meteorologic agencies not fully understood,
they advance and retreat in alternate periods, at one time
receding for a considerable distance, and at other times
regaining the lost ground and advancing over the area
which has been uncovered by their retreat.

‘““M. Forel reports, from the data which he has col-
lected with much care, that there have been in this cent-
ury five periods in the Alpine glaciers: of enlargement,
from 1800 (?) to 1815; of diminution, from 1815 to
1830; of enlargement, from 1830 to 1845 ; of diminution,
from 1845 to 1875; and of enlargement again, from 1875
onward. He remarks further that these periods corre-
spond with those deduced by Mr. C. Lang for the varia-
tions for the precipitations and temperature of the air;
and, consequently, that the enlargement of the glaciers
has gone forward in the cold and rainy period, and the
diminution in the warm and the dry.” *

When, now, we attentively consider the combination
of causes necessary to produce the climatic conditions of
the great Ice age of North America, we shall be prepared
to find far more extensive variations in the progress of
the continental glacier, both during its advance and dur-
ing its retreat, than are to be observed in any existing
local glaciers. |

With respect to the arguments adduced in favor of a
succession of glacial epochs in America the following
criticisms are pertinent:

* American Journal of Science, vol. exxxii, 1886, p. 77.

ANCIENT GLACIERS. LAT

1. So far as we can estimate, a temporary retreat of
the front, lasting a few centuries, would be sufficient to
account for the vegetable accumulations that are found
buried beneath the glacial deposits in southern Ohio, In-
diana, central Illinois, and Iowa, while a temporary re-
advance of the ice would be sufficient to bury the vegeta-
ble remains beneath a freshly accumulated mass of till.
Thus, as Dr. Bell suggested, the interglacial vegetal de-
posits do not necessarily indicate anything more than a
temporary oscillation of the ice-front, and do not carry
with them the necessity of supposing a disappearance of
the ice from the whole glaciated area. Thus the introduc-
tion of a whole Glacial period to account for such limited
phenomena is a violation of the well-known law of parsi-
mony, which requires us in our explanations of phenomena
to be content with the least cause which is sufficient to
produce them, In the present instance a series of com-
paratively slight oscillations of the ice-front during a
single glacial period would seem to be sufficient to ac-
count for all the buried forests and masses of vegetal
débris that occur either in the United States or in the
Dominion of Canada. :

2. Another argument for the existence of two abso-
lutely distinct glacial periods in North America has been
drawn from the greater oxidation of the clays and the
~ more extensive disintegration of certain classes of the bould-
ers found over the southern part of the glaciated area of
the Mississippi Valley, than has taken place in the more
northerly regions. Without questioning this statement
of fact (which, however, I believe to be somewhat exag-
gerated), it is not difficult to see that the effects probably
are Just what would result from a single long glacial pe-
riod brought about by such causes as we have seen to be
probably in operation in America. For if one reflects
upon the conditions existing when the Glacial period be-
gan, he will see that, during the long ages of warm cli-

118 MAN AND THE GLACIAL PERIOD.

mate which characterised the preceding period, the rocks
must have been extensively disintegrated through the
action of subaérial agencies. The extent to which this
disintegration takes place can be appreciated now only
by those who reside outside of the glaciated area, where
' these agencies have been in uninterrupted action. In the
Appalachian range south of the glaciated region the gra-
- nitic masses and strata of gneiss are sometimes found to be
completely disintegrated to a depth of fifty or sixty feet;
and what seem to be beds of gravel often prove in fact to
be horizontal strata of gneiss from which the cementing
material has been removed by the slow action of acids
brought down by the percolating water.

Now, there can be no question that this process of
disintegration had proceeded to a vast extent before the
Glacial period, so that, when the ice began to advance,
there was an enormous amount of partially oxidised and
disintegrated material ready to be scraped off with the
first advance of ice, and this is the material which would
naturally be transported farthest to the south; and thus,
on the theory of a single glacial period, we can readily ac-
count for the greater apparent age of the glacial débris
near the margin. This débris was old when the Glacial
period began.

3. With reference to the argument for two distinct
glacial periods drawn from the smaller apparent amount
of glacial erosion over the southern part of the glaciated
area, we have to remark that that would occur in case of
a single ice-invasion as well as in case of two distinct ice-
invasions, in which the later did not extend so far as
the former.

From the very necessity of the case, glacial erosion
diminishes as the limit of the extent of the glaciation is
approached. At the very margin of the glacier, motion
has ceased altogether. Back one mile from the margin
only one mile of ice-motion has been active in erosion,

“y

—

ANCIENT GLACTERS. 1s

while ten miles back from its front there has been ten
times as much moving ice actually engaged in erosion,
and in the extreme north several hundred times as much
ice, Thus it is evident that we do not need to resort to
two glacial periods to account for the relatively small
amount of erosion exhibited over the southern portion of
our glaciated area.

At the same time, it should be said that the indica-
tions of active glacial erosion near the margin are by no
means few or small. In Lawrence County, Pennsylvania,
on the very margin of the glaciated area, Mr. Max Fo-
shay * has discovered very extensive glacial grooves, indicat-
ing much vigour of ice-action even beyond the more exten-
sive glacial deposits which Professor Lewis and myself had
fixed upon as the terminal moraine. In Highland and
Butler Counties, Ohio, and in southwestern Indiana and
southern Illinois, near the glacial margin, glacial grooves
and striz are as clear and distinct in many cases as can
anywhere be found; while upon the surface of the lime-
stone rocks within the limits of the city of St. Louis,
where the glacial covering is thin, and where disintegrat-
ing agencies had had special opportunities to work, I
found very clear evidences of a powerful ice-movement,
which had planed and scratched the rock surface; and
at Du Quoin, Illinois, as already related, the fragments
thrown up from the surface of the rock, fifty or sixty feet
below the top of the soil, were most beautifully planed
and striated. It should be observed, also, that this whole
area is so deeply covered with dédris that the extent of
glacial erosion underneath is pretty generally hid from
view.

4. The uniformity of the distribution of the glacial
deposits over the southern portion of the glaciated area in
the Mississippi Valley is partly an illusion, due to the

* Bulletin of the Geological Society, vol. ii, pp. 457-464.

120 MAN AND THE GLACIAL PERIOD.

fact that there was a vast amount of deposition by water
over that area during the earlier stages of the ice-retreat.
This has been due partly to the gentler slope which would
naturally characterise the borders of an area of elevation,
and partly to an extensive subsidence which seems to have
begun soon after the ice had reached its farthest extent of
motion.

It should be borne in mind that at all times a glacier
is accompanied by the issue of vast streams of water from
its front, and that these of course increase in volume when
the climax has been reached and the ameliorating influ-
ences begin to melt away the accumulated mass of ice
and to add the volume of its water to that produced by
ordinary agencies. As these subglacial streams of water
poured out upon the more gentle slopes of the area in
front of the ice, they would distribute a vast amount of
fine material, which would settle into the hollow places
and tend to obscure the irregularities of the previous di-
rect glacial deposit.

Such an instance came clearly under my own observa-
tion in the vicinity of Yankton, in South Dakota, where,
upon visiting a locality some miles from any river, and to
which workmen were resorting for sand, I found that the
deposit occupied a kettle-hole, filling it to its brim, and
had evidently been superimposed by a temporary stream of
water flowing over the region while the ice was still in
partial occupation of it. Thus, no doubt, in many cases,
the original irregularities of the direct glacial deposits
have been obliterated, even where there has been no gen-
eral subsidence.

But, in the area under consideration, the loess, or
loam, is so extensive that it is perhaps necessary to sup-
pose that the central portions of the Mississippi Valley
were subjected to a subsidence amounting to about five
hundred feet; so that the glacial streams from the retreat-
ing ice-front met the waters of the ocean in southern

ANCIENT GLACIERS. 121

Illinois and Indiana; thus accounting for the extensive
fine silt which has done so much over that region to
obscure the glacial phenomena.

West of the Rocky Mountains.

The glacial phenomena in the United States west of
the Rocky Mountains must be treated separately, since
American geologists have ceased to speak of an all-per-
vading ice-cap extending from the north pole. But, as
already said, the glaciation of North America has proceed-
ed from two definite centres of ice-accumulation, one of
which we have been considering in the pages immediately
preceding. The great centre of glacial dispersion east of
the Rocky Mountains is the region south of Hudson Bay,
and the vast ice-field spreading out from that centre is
appropriately named the Laurentide Glacier. ‘The move-
ment of ice in this glacial system was outward in all
directions from the Laurentian hills, and extended west
several hundred miles, well on towards the eastern foot of
the Rocky Mountains.

The second great centre of glacial dispersion occupies
the vast Cordilleran region of British Columbia, reaching
from the Rocky Mountains on the northeast to the Coast
Range of the Pacific on the southwest, a width of four
hundred miles.. The length is estimated by Dr. Dawson
to be twelve hundred miles. The principal centre of ice-
accumulation les between the fifty-fifth and the fifty-
ninth parallel. From this centre the movement was in
all directions, but chiefly to the northwest and to the
south. The movement of the Cordilleran glaciers ex-
tended northwest to a distance of three hundred and
fifty miles, leaving their moraines far down in the Yukon
Valley on the Lewes and Pelly Rivers.* Southward the

* See George M. Dawson, in Science, vol. xi, 1888, p. 186, and
American Geologist, September, 1890, pp. 153-162.

122 MAN AND THE GLACIAL PERIOD.

Cordilleran Glacier moved to a distance of six hundred
miles, extending to the Columbia River, in the eastern
part of the State of Washington.

From this centre, also, the ice descended to the sea-
level upon the west, and filled all the channels between
Vancouver’s Island and the mainland, as well as those in
the Alexander Archipelago of Alaska. South of Van-
couver’s Island a glacier pushed out through the straits of
Juan de Fuca to an unknown distance. All the islands
in Puget Sound are composed of glacial débris, resem-
bling in every respect the terminal moraines which have
been described as constituting many of the islands south
of the New England coast. The ice-movement in Puget
Sound, however, was probably northward, resulting from
glaciers which are now represented by their diminutive
descendants on the flanks of Mount Rainier. |

South of the Columbia River the country was never
completely enveloped by the ice, but glaciers extended far
down in the valleys from all the lofty mountain-peaks. In
Idaho there are glacial signs from the summit of the Rocky
Mountains down to the westward of Lake Pend d’Oreille.
In the Yellowstone Park there are clear indications that
the whole area was enveloped in glacial ice. An immense
boulder of granite, resting upon volcanic deposits, may be
found a little west of Inspiration Point, on the Yellow-
stone Cafion. Abundant evidences of glacial action are
also visible down the Yellowstone River to the vicinity of
Livingston, showing that that valley must have been
filled with glacial ice to a depth of sixteen hundred feet.
To the west the glaciers from the Yellowstone Park ex-
tended to the border of Idaho, where a clearly marked
terminal moraine is to be found in the Tyghee Pass, lead-
ing over from the western fork of the Madison River into
Lewis Fork of the Snake River. South of Yellowstone
Park the Teton Mountains were an important centre for
the dispersion of local glaciers, but they did not descend

ANCIENT GLACIERS. 123

upon the western side much below the 6,000-foot level,
and only barely came to the edge of the great Snake
River lava plains. To the east the movement from the
Teton Mountains joined that from various other lofty
mountains, where altogether they have left a most intri-
cate system of glacial deposits, in whose reticulations Jack-
son’s Lake is held in place.

In Utah extensive glaciers filled all the northern val-
leys of the Uintah Mountains, and extended westward in
the Wahsatch range to the vicinity of Salt Lake City.
The mountain region of Colorado, also, had its glaciers,

Fic. 37.—Moraines of Grape Creek, Sangre del Cristo Mountains, Colorado (after
Stevenson).

occupying the head-waters of the Arkansas, the Platte, the

Gunnison, and the Grand Rivers. The most southern

point in the Rocky Mountains at which signs of local

glaciers have been noted is near the summits of the San

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124 MAN AND THE GLACIAL PERIOD.

Juan range, in southwestern Colorado. Here a surface of
about twenty-five square miles, extending from an eleva-
tion of 12,000 feet down to 8,000 feet, shows every sign of
the former presence of moving ice. The greater part of
the glaciation in Colorado is confined to elevations above
10,000 feet.

The whole range of the Sierra Nevada through Ore-
gon, and as far south as the Yosemite Valley in Califor-
nia, formerly sustained glaciers of far greater size than
any which are now found in those mountains. In general
these glaciers were much longer on the western side of the
Sierra Nevada than on the eastern. On the eastern side
glaciers barely came down to Lake Tahoe and Lake Mono
in California. The State of Nevada seems to have been
entirely free from glaciers, although it contains numer-
ous mountain-peaks more than ten thousand feet high.
In the Yosemite Cafion glaciers extended down the Mer-
ced River tothe mouth of the cafion; while in the Tuo-
lumne River, a few miles to the north, the glaciers which
still linger about the peaks of Mount Dana filled the val-
ley for a distance of forty miles.

It is a question among geologists whether or not the
glaciation west of the Rocky Mountains was contempo-
raneous with that of the eastern part of the continent.
The more prevalent opinion among those who have made
special study of the phenomena is that the development of
the Cordilleran glaciers was independent of that of the
Laurentide system. At any rate, the intense glaciation of
the Pacific coast seems to have been considerably later than
that of the Atlantic region. Of this we will speak more
particularly in discussing the questions of the date and
the cause of the Glacial period. It is sufficient for us
here simply to say that, from his extensive field observa-
tions throughout the Cordilleran region, Dr. George M.
Dawson infers that there have been several successive al-
ternations of level on the Pacific coast corresponding to

ANCIENT GLACIERS. 125

successive glacial and interglacial epochs, and that when
there was a period of elevation west of the Rocky Mount-
ains there was a period of subsidence to the east, and vice
versa. In short, he supposes that the east and west for a
long time played a game of seesaw, with the Rocky
Mountains as the fulcrum. We give his scheme in tabu-
lated form.

Scheme of Correlation of the Phenomena of the Glacial

Period in the Cordilleran Region and in the hegion

of the Great Plains.

CORDILLERAN REGION.

Cordilleran zone at a high
elevation. Period of most severe
glaciation and maximum devel-
opment of the great Cordilleran
Glacier.

Gradual subsidence of the
Cordilleran region and decay of
the great glacier, with deposition
of the boulder-clay of the interi-
or plateau and the Yukon basin,
of the lower boulder-clay of the
littoral and probably also, at a
later stage (and with greater sub-
mergence), of the interglacial
silts of the same region.

Re-elevation of the Cordil-
leran region to a level probably
as high as or somewhat higher
than the present. Maximum of
second period of glaciation.

REGION OF THE GREAT PLAINS.

Correlative subsidence and
submergence of the great plains,
with possible contemporaneous
increased elevation of the Lau-
rentian axis and maximum de-
velopment of ice upon it. De-
position of the lower bcoulder-
clay of the plains.

Correlative elevation of the
western part, at least, of the great
plains, which was probably more
or less irregular and led to the
production of extensive lakes in
which interglacial deposits, in-
cluding peat, were formed.

Correlative subsidence of the
plains, which (at least in the
western part of the region) ex-
ceeded the first subsidence and
extended submergence to the base
of the Rocky Mountains near the
forty-ninth parallel. Formation
of second boulder-clay, and (at a
later stage) dispersion of large
erratics.

126

Partial subsidence of the Cor-
dilleran region, to a level about
2,500 feet lower than the present.
Long stage of stability. Glaciers
of the second period considerably
reduced. Upper boulder-clay of
the coast probably formed at this
time, though perhaps in part dur-
ing the second maximum of gla-
ciation. 3

Renewed elevation of the Cor-
dilleran region, with one well-
marked pause, during which the
littoral stood about 200 feet lower
than at present. Glaciers much
reduced, and diminishing in con-
sequence of general amelioration
of climate towards the close of
the Glacial period.

MAN AND THE GLACIAL PERIOD.

Correlative elevation of the
plains, or at least of their west-
ern portion, resulting in a condi-
tion of equilibrium as between
the plains and the Cordillera,
their relative levels becoming
nearly as at present. Probable
formation of the Missouri co-
teau along a shore-line during
this period of rest.

Simultaneous elevation of the
great plains to about their pres-
ent level, with final exclusion of
waters in connection with the
sea. Lake Agassiz formed and
eventually drained towards the
close of this period. This simul-
taneous movement in elevation
of both great areas may probably
have been connected with a more
general northern elevation of
land at the close of the Glacial
period.

In New Zealand the marks of the Glacial period are

unequivocal.

The glaciers which now come down from

mn “7

the lofty mountains upon the South Island of New Zea-
land to within a few hundred feet of the sea then de-
scended to the sea-level. The longest existing glacier in
New Zealand is sixteen miles, but formerly one of them
had a length of seventy-eight miles. One of the ancient
moraines contains a boulder from thirty to forty feet in
diameter, and the amount of glacial débris covering the
mountain-sides is said to be enormous. Reports have also
been recently brought of signs of ancient glaciers in Aus-
tralia.

According to Darwin, there are distinct signs of glacia-
tion upon the plains of Patagonia sixty or seventy miles
east of the foot of the mountains, and in the Straits of Ma-

127

ANCIENT GLACIERS.

gellan he found great masses of unstratified glacial material

containing boulders which were at least one hundred and

thirty miles away from their parent rock; while upon the

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part of Alaska.

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128 MAN AND THE GLACIAL PERIOD.

island of Chiloe he found embedded in “ hardened mud ”
boulders which must have come from the mountain-chains
of the continent. Agassiz also observed unquestionable
glacial phenomena on various parts of the Fuegian coast,
and indeed everywhere on the continent south of latitude
37°. Between Concepcion and Arauco, in latitude 37°,
Agassiz observed, near the sea-level, a glacial surface well
marked with furrows and scratches, and as well preserved,
he says, “as any he had seen under the glaciers of the

present day.”

Fie. 39.—Quartzite boulder of 45 cubic metres, on Mont Lachat, 800 metres above
the valley of the Belley, in Ain, France (Falsan).

CHEAPAIR: Vial
ANCIENT GLACIERS IN THE EASTERN HEMISPHERE.

Axsout two million square miles of northern Europe
were covered with perennial ice during the Glacial period.
From the scratches upon the rocks, and from the direction
in which material has been transported, it is evident that
the main centre of radiation is to be found in the mount-
ains of Scandinavia, and that the glaciers still existing in
Norway are the lineal descendants of those of the great
Ice age.

So shallow are the Baltic Sea and the German Ocean,
that their basins were easily filled with ice, upon which
Scandinavian boulders could be transported westward to
the east shore of England, southward into the plains of
Germany, and eastward far out upon the steppes of Russia.
The islands north of Scotland bear marks also of an ice-
movement from the direction of Norway. If Scotland
itself was not overrun with Scandinavian glaciers, the
reason was that it had ice enough of its own, and from
its highlands set up a counter-movyement, which success-
fully resisted the invasion from the Scandinavian Penin-
sula. But, elsewhere in Europe, Scandinavian ice moved
freely outward to the extent of its capacity. ‘Then, as
now also, the Alps furnished centres for ice-moyement,
but the glaciers were limited to the upper portions of the
valleys of the Rhone, the Rhine, and the Danube upon
the west and north, and to a still smaller area upon the
southern side.

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ANCIENT GLACIERS IN EASTERN HEMISPHERE. 131

Central and Southern Europe.

The main centres of ice-movement in the Alps during
the Glacial period are the same as those which furnish
the lingering glaciers of the present time. From the
water-shed between the Rhine, the Rhéne, and the Aar,
glaciers of immense size descended all the valleys now
occupied by those streams. The valley of the Rhdéne be-
tween the Bernese and the Pennine Alps was filled with a
glacier of immense depth, which was maintained by fresh
supplies from tributaries upon either side as far down as
Martigny. Glacial markings at the head of the Rhdéne
Valley are found upon the Schneestock,* at an elevation
above the sea of about 11,500 feet (3,550 metres), or
about 1,500 feet above the present surface of the Rhone
Glacier. At Fiesch, about twenty miles below, where
tributaries from the Bernese Oberland snow-fields were
received, the thickness of the glacier was upwards of 5,000
feet (1,680 metres). Near Martigny, about fifty miles
farther down the valley, where the glacier was abruptly de-
flected to the north, the depth of the ice was still upwards
of 1,600 metres. From Martigny northward the thick-
ness of the ice decreased rapidly for a few miles, where,
at the enlargement of the valley above the head of Lake
Geneva, it was less than 1,200 metres in thickness, and
spread out over the intervening plain as far as Chasseron,
with a nearly level surface, transporting, as we have before
said, Alpine boulders to the flanks of the Juras, and land-
ing them about 3,000 feet (1,275 metres) above the level
of Lake Geneva. The width of the main valley is here
about fifty miles, making the slope of the surface of the
ice about twenty feet to the mile.

From its “ vomitory,” at the head of Lake Geneva, the

* A. Falsan’s La Période Glaciaire étudiée principalement en
France et en Suisse, chapitre xy.

Be MAN AND THE GLACIAL PERIOD.

ice of the ancient Rhéne Glacier spread to the right and
to the left, while its northern boundary was abruptly ter-
minated by the line of the Jura Mountains. The law of
glacial motion was, however, admirably illustrated in the
height to which the ice rose upon the flanks of the Jura.
At Chasseron, in the direct line of its onward motion, it
rose to its highest point, while both to the southwest and
to the northeast, along the line of the Juras, the ice-
action was limited to constantly decreasing levels.

Down the valley of the Rhone the direction of motion
was determined by the depression of Lake Geneva, at the
lower end of which it received its main tributary from
Mont Blane, which had come down from Chamouni
through the valley of the river Arve. From this point it
was deflected by a spur of the Jura Mountains more and
more southward to the vicinity of Culoz, near the mouth
of Lake Bourget. Here the glacier coming down from
the western flanks of the Alps, through the upper valley
of the Isére, past Chambéry, became predominant, and
deflected the motion to the west and north, whither the
ice extended to a line passing through Bourg, Lyons, and
Vienne, leaving upon one of the eminences on which
Lyons is built a boulder several feet in diameter, which is
duly preserved and labelled in the public park in that
portion of the city. Farther south, glaciers of less extent
marked the Alps most of the way to the Mediterranean,
but they were not at all comparable in size to those from
the central region.

To the right of Lake Geneva the movement started by
the Rhone Glacier spread eastward, being joined in the
vicinity of Berne by the confluent ice-stream which de-
scended from the north flank of the Bernese Oberland,
through the valley of the Aar. These united streams
filled the whole valley with ice as far down as Soleure.*

* See map of Rhone Glacier, on p. 58.

\

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Greenwich

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Orleans,

Bloisg

MAP OF

GLACIAL MOVEMENTS
IN FRANCE AND
SWITZERLAND.

COMPILED BY FALSAN,

Arrows indicate direction of motion.

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ie EROF &

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gi

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Maat \ Longitude. 4

East)

from

§ Greenwich

ANCIENT GLACIERS IN HASTERN HEMISPHERE. 133

Farther eastward, other ice-streams from the Alps be-
came predominant, one of which, moving down the Reuss,
deployed out upon the country lying north of Lucerne
and Zug. Still farther down, the ancient glacier which
descended the Limmatt spread itself out over the hills
and lowlands about Zurich, one of its moraines of retro-
cession nearly dividing the lake into two portions.

Guyot and others have shown that the superficial de-
posits of this portion of Switzerland are just such as would
be distributed by glaciers coming down from the above-
mentioned Alpine valleys. Uniting together north of
Zurich, these glaciers pushed onward as far as the Rhine
below Schaffhausen. In Frickthal the glacial ice was still
1,200 feet thick, and at Kaisterberg between 400 and 500
feet.

At Lucerne there is a remarkable exposure of pot-
holes, and a glaciated surface such as could be produced
only by the combined action of moving ice and running
water; thus furnishing to tourists an instructive object-
lesson. Among the remarkable instances of boulders
transported a long distance in Switzerland, is that of a
block of granite carried from the Valais to the vicinity of
Soleure, a distance of one hundred and fifteen miles, which
weighs about 4,100 tons. ‘The celebrated Pierre-a-Bot,
above Neufchatel, measures 50’ X 20’ x 40’, and contains
about 40,000 cubic feet of stone; while the Pierre-des-
Marmettes, near Monthey, contains no less than 60,840
cubic feet.”

The ancient glacier of the Rhine, receiving its initial
impulse in the same centre as that of the Rhone, fully
equalled it in all its dimensions. Descending eastward
from its source near the Schneestock to Chur, a distance
of fifty miles, it turned northward and continued forty-
five miles farther to the head of Lake Constance, where it
spread out in fan-shape, extending northwest to Thiengen,
below Schaffhausen, and covering a considerable area north

134 MAN AND THE GLACIAL PERIOD.

and northeastward of the lake, reaching in the latter di-
rection Ulm, upon the Danube—the whole distance of the
movement being more than one hundred and fifty miles.
Through other valleys tributary to the Danube, glaciers
descended upon the upper plains of Bavaria, from the
Tyrolese Alps to the vicinity of Munich. From Gross
Glockner as a centre in the Noric Alps, vast rivers of ice,
of which the Pasterzen Glacier is the remnant, poured
far down into the valleys of the Inn and the Enns on
the north and into that of the Drave on the southeast.
Farther eastward in this part of Europe the mountains
seem to have been too low to have furnished centres for
any general dispersion of glacial ice.

Upon the south side of the Alps the ancient glaciers
spread far out upon the plains of Lombardy, where mo-
raines of vast extent
and of every descrip-
tion enable the stu-
dent to determine the
exact limits of the
ancient ice - action.
From the southern
flanks of Mont Blane
and Monte Rosa, and
from the snow-fields
of the western Alps,
glaciers of great vol-
ume descended into
the valley of Dora
Baltea (vale of Aos-

a), and on emergin
1@.41.—Map showing the Lines of Débris ex- ta), a ole

tending from the Alps into the Plains of the from the mountain
Po (after Lyell). A. Crest of the Alpine wa-

ter-shed ; B, Neve fields of the ancient gla- valley spread out over
ciers ; (, Moraines of ancient glaciers. ;

the plains around

Ivrea, leaving moraine hills in some instances 1,500 feet in

height. The total length of this glacier was as much as

hy

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 135

one hundred and twenty miles. From the snow-fields in
the vicinity of Mont Cenis, also, glaciers extended down
the Dora Ripera to the vicinity of Turin, and down other
valleys to a lessextent. The lateral moraines of the Diore,
on the south side of Mont Blanc, at the head of the Dora
Baltea, are 2,000 feet above the present river, and extend
upon the left bank for a distance of twenty miles.

From the eastern Alps, glaciers descended through all
the valleys of the Italian lakes and deposited vast terminal
moraines, which still obstruct the drainage, and produce
the charming lakes of that region. A special historic
interest pertains to the series of concentric moraines south
of Lake Garda, since it was in the reticulations of this
glacial deposit that the last great battle for Italian liberty
was fought on June 24, 1859. Defeated in the engage-
ments farther up the valley of the Po, the Austrian
general Benedek took his final stand to resist the united
forces of France and Italy behind an outer semicircle of
the moraine hills south of this lake (some of which are
500 or 600 feet above the surrounding country), with his
centre at Solferino, about ten miles from Peschera. Here,
behind this natural fortification, he awaited the enemy,
who was compelled to perform his manceuyres on the open
plain which spread out on every side. But the natural
fortifications furnished by the moraine hills were toe ex-
tensive to be defended by an army of moderate size. The
troops of Napoleon and Victor Immanuel concentrated at
Solferino and broke through the line. Thus the day was
lost to the Austrians, and they retired from Lombardy,
leaving to Italy both the artificial and the natural fortifi-
cations that guard the southern end of this important
entrance to the Tyrolese Alps. When once his attention
is called to the subject, the traveller upon the railroad
cannot fail to notice this series of moraines, as he enters
it through a tunnel at Lonato on the west, and emerges
from it at Soma Campagna, eighteen or twenty miles dis-

136 MAN AND THE GLACIAL PERIOD.

tant to the east. A monument celebrating the victory
stands upon a moraine hill about half-way between, at
Martino della Battaglie.

In other portions of central and southern Europe the
mountains were too low to furnish important centres for
glacial movements. Still, to a limited extent, the signs
of ancient glaciers are seen in the mountains of the Black
Forest, in the Harz and Erzgebirge, and in the Carpathians
on the east and among the Apennines on the south. In
Spain, also, there were limited ice-fields on the higher por-
tions of the Sierra Nevada and in the mountains of Hstre-
madura, and perhaps in some other places. In France,
small glaciers were to be found in the higher portions of
the Auvergne, of the Morvan, of the Vosges, and of the
Cevennes; while, from the Pyrenees, glaciers extended

northward throughout nearly their whole extent. The ~

ice-stream descending from the central mass of Maladetta
through the upper valley of the Garonne, was joined by
several tributaries, and attained a length of about forty-
five miles.

The British Isles.

During the climax of the Glacial period the Hebrides
to the north of Scotland were covered with ice to a depth
of 1,600 feet. How far westward of this it moved out
to the sea, it is of course impossible to tell. But in the
channels between the Hebrides and Scotland it is evident
that the water was completely expelled by the ice, and
that, from a height of 1,600 feet above the Hebrides to the
northern shores of Scotland, there was a continuous ice-
field sloping southward at the rate of about twenty-five
feet a mile.

Scotland itself was completely enveloped in glacial ice.
Prevented by the Scandinavian Glacier from moving east-
ward, the Scotch movement was compelled to be westward
and southward. On the southwest the ice-stream reached

re
-
xe
'

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 137

the shores of Ireland, and became confluent with the
glaciers that enveloped that island, completely filling the
Trish Sea.

There are so many controverted points respecting the
glacial geology of England, and they have such an impor-
tant bearing upon the main question of this volume, that
a pretty full discussion of them will be necessary. I have
recently been over enough of the ground myself to become
satisfied of the general correctness of the views entertained
by my late colleague, the lamented Professor Henry Car-
vill Lewis, whose death in 1888 took place before the pub-
lication of his most mature conclusions. But the lines of
investigation to which he gave so powerful an impulse
have since been followed out by an active body of scien-
tific observers. To give the statement of facts greater
precision and authority, I have committed the preparation
of it to the Secretary of the Northwest of England Boul-
der Committee, Percy F. Kendall, F. G. S., Lecturer on
Geology at the Yorkshire College, Leeds, and at the
Stockport Technical School, England.*

“All the characteristic evidences of the action of land-
ice can be found in the greatest perfection in many parts
of England and Wales. Drumlins, kames, roches mouton-
nées, far-trayelled erratics, terminal moraines, and perched
blocks, all occur. There are, besides, in the wide-spread
deposits of boulder-clay which cover so many thousands
of square miles on the low grounds lying on either side of
the Pennine chain, evidences of the operation of ice-
masses of a size far exceeding that of the grandest of ex-
isting European glaciers. But, while the proofs of pro-
tracted and severe glaciation are thus patent, there are,
nevertheless, many apparently anomalous circumstances
which arrest the attention when the whole country is sur-
veyed. The glacial phenomena appear to be strictly lim-
ited to the country lying to the northward of a line ex-

* Mr. Kendall’s contribution extends to page 181,

138 MAN AND THE GLACIAL PERIOD.

tending from the Bristol Channel te the mouth of the
Thames; and within the glaciated area there are many
extensive tracts of land devoid of ‘drift’ or other indi-
cations of ice-action.

“By comparison with the phenomena displayed in the
North American continent, English glacial geology must
seem puny and insignificant; but, just as with the feat-
ures of the ‘Solid Geology,’ we have compressed within
the narrow limits of our isles an epitome of the features
which across the Atlantic require a continent for their

exposition. It has resulted from this concentration that _

English geology requires a much closer and more minute
investigation. And the difficulty which has been experi-
enced by glacial geologists of dealing with an involved
series of facts has, in the absence of any clue leading to the
co-ordination of a vast series of more or less disconnected
observations, resulted in the adoption, to meet certain local
anomalies, of explanations which were very difficult if not
impossible of reconciliation with facts observed in adjacent
areas. ‘Thus, to account for shell-bearing drift extending
up to the water-shed on one side of a lofty range of hills, a
submergence of the land to a depth of 1,400 feet has been
postulated ; leaving for independent explanation the fact,
that the opposite slopes of the hills and the low ground
beyond were absolutely destitute of drift or of any evidence
of marine action.

“Tn the following pages I must adopt a somewhat dog-
matic tone, in order to confine myself within the limits of
space which are imposed; and trust rather to the cohesion
and consistency of the explanations offered and to a few
pregnant facts than to the weighing and contrasting of
rival theories.

“The facts point conclusively to the action in the Brit-
ish Isles of a series of glaciers radiating outward from the
great hill chains or clusters, and, as the refrigeration pro-
gressed, becoming confluent and moving though in the

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 139

same general direction, yet with less regard to the minor
inequalities of the ground. During these two stages many
glaciers must have debouched upon the sea-coast, with the
consequent production of icebergs, which floated off with
loads of boulders and dispersed them in the random fash-
ion which is a necessary characteristic of transport by
floating ice.

“ With a further accentuation of the cold conditions
the discharge of bergs from terminal fronts which advanced
into the extremely shallow seas surrounding the British
shores would be quite inadequate to relieve the great press
of ice, and a further coalescence of separate elements must
have resulted. In the case of enclosed seas—as, for exam-
ple, the Irish Sea—the continued inthrust of glacier-ice
would expel the water completely ; and the conjoined ice-
masses would take a direction of flow the resultant of the
momentum and direction of the constituent elements. In
other cases—as, for example, in the North Sea—extraneous
ice approaching the shores might cause a deflection of the
flow of the native glaciers, even though the foreign ice
might never actually reach the shore.

“To such a system of confluent glaciers, and to the
separate elements out of which they grew, and into which,
after the culmination, they were resolved, I attribute the
whole of the phenomena of the English and Welsh drift.
And only at one or two points upon the coast, and raised
but little above the sea-level, can I recognise any signs
of marine action.

“ The Pre-glacial Level of the Land.—There is very lit-
tle direct evidence bearing upon this point. In Norfolk
the famous forest bed, with its associated deposits, stands at
almost precisely the level which it occupied in pre-glacial
times. At Sewerby, near Flamborough Head, there is an
ancient beach and ‘buried cliff’ which the sea is now de-
nuding of its swathing of drift deposits, and its level can
be seen to be almost absolutely coincident with the present

140 MAN AND THE GLACIAL PERIOD.

beach. Mr. Lamplugh, whose description of the ‘ Drifts
of Flamborough Head,’* constitutes one of the gems of
glacial literature, considers that there is clear evidence
that the land stood at this level for a long period. The
beach is covered by a rain-wash of small extent, and that
in turn by an ancient deposit of blown sand, while the
lowest member of the drift series of Yorkshire covers the
whole. Mr. Lamplugh thinks that the blown sand may
indicate a slight elevation of the land; but the beach ap- —
pears to me to be the storm beach, and the reduction in
the force of the waves such as would result from the ap-
proach of an ice-front a few miles to the seaward would
probably produce the necessary conditions.

“Six miles to the northward of Flamborough, at Spee-
ton, a bed of estuarine silt containing the remains of mol-
lusca in the position of life occurs at an altitude of ninety
feet above high-water mark. Mr. Lamplugh inclines to
the opinion that this bed is of earlier date than the ‘ buried
cliff’; he also admits the possibility that its superior alti-
tude may be due to a purely local upward bulging of the
soft Lower Cretaceous clays upon which the estuarine bed
rests by the weight of the adjacent lofty chalk escarp-
ment.

“The evidence obtained from inland sections and bor-
ings indifferent parts of England has been taken to in-
dicate a greater altitude in preglacial times. Thus, in
Essex, deep borings have revealed the existence of deep
drift-filled valleys, having their floors below sea-level.
The valley of the Mersey is a still better example. Nu-
merous borings have been made in the neighbourhood of
Widnes and at other places in the lower reaches of the
river, making it clear that there is a channel filled with
drift and extending to 146 feet below mean sea-level.
This, with several other instances, has been taken to in-

* Quarterly Journal of the Geological Society, vol. xlvii.

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 141

dicate a greater altitude for the land in pre-glacial times,
since a river could not erode its channel to such a depth
below sea-level. The argument appears inconclusive for
one principal reason: no mention is made of any river
gravels or other alluvium in the borings. Indeed, there
is an explicit statement that the deposits are all glacial,
showing that the channel must have been cleared out by
ice. This, therefore, leaves open the vital question,
whether the deposits removed were marine or fluviatile.
It may be remarked that the great estuary of the Mersey
has undoubtedly been produced by a post-glacial (and
probably post-Roman) movement of depression.

“ The Pre-Glacial Climate.—In all speculations regard-
ing the cause of the Glacial epoch, due account must be
taken of the undoubted fact that it came on with extreme
slowness and departed with comparative suddenness. In
the east of England an almost perfect and uninterrupted
sequence of deposits is preserved, extending from the early
part of the Pliocene period down to the present day.

“These in descending order are :

“1. Post-glacial sands, gravels, ete.

2. Glacial series.

“3. The ‘ Forest Bed’ and associated marine deposits.

“4, Chillesford clay and sand.

“5. The many successive stages of the Red Crag. (The
Norwich Crag is a local variation of the upper part of the
Red Crag.)

“6. The Coralline Orag.

“The fossils preserved in these deposits, apart from the
physical indications, exhibit the climatal changes which
accompanied their deposition. The Coralline Crag con-
tains a fauna consisting mainly of species which now
range to the Mediterranean, many of them being restricted
to the warm southern waters. Associated with these are
a few boreal forms, but they are represented in general
by few individuals. Here and there in the deposits of

142 MAN AND THE GLACIAL PERIOD.

this age far-travelled stones are to be found, but they are
always accounted great rarities.

“The Red Crag consists of an irregular assemblage of
beaches and sand-banks of widely different ages, but their
sequence can be made out with ease by a study of the
fauna. In the oldest deposits, Mediterranean species are
very numerous, while the boreal forms are comparatively
rare; but in successive later deposits the proportions are
very gradually reversed, and from the overlying Chilles-
ford series the Mediterranean species are practically ab-
sent. The physical indications run pari passu with the
paleontological, and in the newer beds of the Red Crag
far-travelled stones are common.

“In the Forest Bed series there is a marine band—the
Leda myalis bed—which contains an almost arctic assem-
blage of shells; while at about the sanie horizon plant
remains have been found, including such high northern
species as Saliz polaris and Betula nana.

“The glacial deposits do not, in my opinion, contain
anywhere in England or Wales a genuine intrinsic fauna,
such shells as occur in the East Anglian glacial deposits
having been derived in part from a contemporary sea-bed,
and, for the rest, from the older formations, down perhaps
to the Coralline Crag. In the post-glacial deposits we
have hardly any trace of a survival of the boreal forms,
and I consider that the whole marine fauna of the North
Sea was entirely obliterated at the culmination of the
Glacial epoch, and that the repeopling in post-glacial
times proceeded mainly from the English Channel, into
which the northern forms never penetrated.

“ The Great Glacial Centres.

““ Where such complex interactions have to be described
as were produced by the conflicting glaciers of the British
Isles it is difficult to deal consecutively with the phe-
nomena of any one area, but with short digressions in ex-

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 143

planation of special points it may be possible to accom-
plish a clear presentation of the facts.

“« Wales.—The phenomena of South Wales are com-
paratively simple. Great glaciers travelled due southward
from the lofty Brecknock Beacons, and left the charac-
teristic moutonnée appearance upon the rocky bed over
which they moved. The boulder-transport is in entire
agreement with the other indications, and there are no
shells in the drift. The facts awaiting explanation are
the occurrence in the boulder-clays of Glamorganshire, at
altitudes up to four hundred feet, of flints, and of igneous
rocks somewhat resembling those of the Archean series
of the Wrekin. At Clun, in Shropshire, a train of erratics
(see map) has been traced back to its source to the west-
ward. On the west coast, in Cardigan Bay, the boulders
are all such as might have been derived from the interior
of Wales. At St. David’s Peninsula, Pembrokeshire, strize
occur coming in from the northwest, and, taken with the
discovery of boulders of northern rocks, may point to a
southward extension of a great glacier produced by conflu-
ent sheets that choked the Irish Sea. Information is very
scanty regarding large areas in mid-Wales, but such as
can be gathered seems to point to ice-shedding haying
taken place from a north and south parting line. In
North Wales, much admirable work has been done which
clearly indicates the neighbourhood of Great Arenig
(Arenig Mawr) as the radiant point for a great dispersal
of blocks of volcanic rock of a characteristic Welsh type.

*“* Ireland.—A brief reference must be made to Ireland,
as the ice which took origin there played an important
part in bringing about some strange effects in English
glaciation, which would be inexplicable without a recog-
nition of the causes in operation across the Irish Sea.
Ireland is a great basin, surrounded by an almost contin-
uous girdle of hills. The rainfall is excessive, and the

snowfall was probably more than proportionately great ;
11

144 MAN AND THE GLACIAL PERIOD,

therefore we might expect that an ice-sheet of very large
dimensions would result from this combination of fa-
vouring conditions. ‘The Irish ice-sheet appears to have
moved outward from about the centre of the island, but
the main flow was probably concentrated through the
gaps in the encircling mountains.

“ Galloway.—The great range of granite mountains in
the southwestern corner of Scotland seems to have given
origin to an immense mass of ice which moved in the main
to the southward, and there are good grounds for the
belief that the whole ice-drainage of the area, even that
which gathered on the northern side of the water-shed,
ultimately found its way into the Irish Sea basin and
came down coastwise and across the low grounds of the
Rinns of Galloway, being pushed down by the press of
Highland ice which entered the Firth of Clyde. It is a
noteworthy fact that marine shells occur in the drift in
the course taken by the ice coming on to the extremity of
Galloway from the Clyde.

“ The Lake District.—A radial flow of ice took place
down the valleys from about the centre of the Cumbrian
hill-plexus, but movement to the eastward was at first for-
bidden by the great rampart of the Cross Fell escarpment,
which stretches like a wall along the eastern side of the
Vale of Eden.

“During the time when the Cumbrian glaciers had
unobstructed access to the Solway Frith, to the Irish Sea,
and to Morecambe Bay, the dispersal of boulders of char-
acteristic local rocks would follow the ordinary drainage-
lines; but, as will be shown later, a state of affairs super-
vened in the Irish Sea which resulted, in many cases, In a
complete reversal of the ice-flow.

“ The Pennine Chain was the source of glaciers of ma-
jestic dimensions upon both its flanks in the region north
of Skipton, but to the southward of that breach in the chain
(see map) no evidence is obtainable of any local glaciers,

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 145

“ The Confluent Glaciers.

‘ With the growth of ice-caps upon the great centres
‘ a condition of affairs was brought about in the Irish Sea
productive of results which will readily be foreseen. The
enormous volumes of ice poured into the shallow sea
from north, south, east, and west, resulted in such a con-
gestion as to necessitate the initiation of some new systems
of drainage.

“ The Irish Sea Glacier.—The ice from Galloway, Cum-
bria, and Ireland became confluent, forming what the late
Professor Carvill Lewis termed ‘the Irish Sea Glacier,’
and took a direction to the southward. Here it came in
diametrical conflict with the northward-flowing element
of the Welsh sheet, which it arrested and mastered; and
the Irish Sea Glacier bifurcated, probably close upon the
precipitous Welsh coast to the eastward of the Little
Orme’s Head, and the two branches flowed coastwise to
eastward and westward, keeping near the shore-line.

“ The westerly branch swept round close to the coast in a
southwesterly direction, and completely overrode Anglesea;
striating the rock-surfaces from northeast to southwest
(see map), and strewing the country with its bottom-mo-
raine, containing characteristic northern rocks, such as the
Galloway granites, the lavas and granites of the central and
western portions of the Lake District, and fragments of
shells derived from shell-banks in the Irish Sea. One epi-
sode of this phase of the ice-movement was the invasion
of the first line of hills between the Menai Straits and
Snowdon. The gravels and sands of Fridd-bryn-mawr,
Moel Tryfaen, and Moel-y-Cilgwyn, are the coarser wash-
ings of the bottom-moraine, and consequently contain such
rock-fragments and shells as characterise it. From Moel-
y-Cilgwyn southward, evidence is lacking regarding the
course taken by the glacier, but it probably passed over
or between the Rivals Mountains (Yr Ejifl), and down

146 MAN AND THE GLACIAL PERIOD.

Cardigan Bay at some distance from the coast in conflu-
ence with the ice from mid-Wales; and, as I have sug-
gested, may have passed over St. David’s Head.

“ Returning now towards the head of the glacier we may
follow with advantage its left bank downward. The ice-
flow on the Cumberland coast appears to have resembled
very much that in North Wales. A great press of ice
from the northward (Galloway) seems to have had a pow-
erful ‘easting’ imparted to it by the conjoint influences
of the thrust of the Irish ice and the inflow of ice from
the Clyde. Whatever may have been the cause, the effect
is clear: about Ravenglass cleavage took place, and a flow
to northward and to southward, each bending easterly.
By far the larger mass took a southerly course and bent
round Black Combe, over Walney, and a strip of the main-
land about Barrow in Furness, and out into and across
Morecambe Bay. Its limits are marked in the field by
the occurrence of the same rocks which characterise it in
Anglesea, viz., the granites of Galloway and of west and
central Cumbria.

“The continued thrust shouldered in the glacier upon
the mainland of Lancashire, but the precise point of
emergence has not yet been traced, though it cannot be
more than a few miles from the position indicated on the
map. I should here remark, that all along the bounda-
ries the Irish Sea Glacier was confluent with local ice,
except, probably, in that part of the Pennine chain to the
southward of Skipton. Down to Skipton there was a
great mass of Pennine ice which was compelled to take
an almost due southerly course, and thus to run directly
athwart the direction of the main hills and valleys. A
sharp easterly inflection of the Irish Sea Glacier carried it
up the valley of the Ribble, and thence, under the shoul-
der of Pendle, to Burnley, where Scottish granites are
found in the boulder-clay.

“On the summit of the Pennine water-shed, at Heald

ANCIENT GLACIERS IN EASTERN HEMISPHERE, 147

Moor, near Todmorden (1,419 feet), boulder-clay has been
found containing erratics belonging to this dispersion ;
while in the gorge of the Yorkshire Calder, which flows
along the eastern side of the same hill, not a vestige of
such a deposit is to be found, saving a few erratic pebbles
at a distance of eight or ten miles, which were probably
carried down by flood-wash from the edge of the ice.

“From this point the lmits of the ice may be traced
along the flanks of the Pennine chain at an average alti-
tude of about 1,100 feet.

“At one place the erratics can be traced to a position
which would indicate the formation of an extra-morainic
lake having its head at a col about 1,000 feet above sea-
level, separating it from the valley of an eastward flow-
ing stream, the Wye, about twelve miles down which a
few granite blocks have been found. Other extra-morainic
lakes must have been formed, but very little information
has been collected regarding them. ‘The Irish Sea Glacier
can be shown to have spread across the whole country
to the westward of the line I have traced, and beyond the
estuary of the Dee.

“I may now follow its boundaries on the Welsh coast,
and pursue the line to the final melting-place of the glacier.
From the Little Orme’s Head the line of confluence with
the native ice is pretty clearly defined. It runs in, per-
haps, half a mile from the shore, until the broad low tract
of the Vale of Clwyd is reached. Here the northern ice
obtained a more complete mastery, and pushed in even
as far as Denbigh. This extreme limit was probably at-
tained as a mere temporary episode. Horizontal striz on
a vertical face of limestone on the crags dominating the
mouth of the vale on the eastern side attest beyond dis-
pute the action of a mass of dand-ice moving in from the
north.

“T may here remark, that in this district the deposits
furnish a very complete record of the events of the Glacial

148 MAN AND THE GLACIAL PERIOD.

period. In the cliffs on the eastern side of the Little
Orme’s Head, and at several other points along the coast
towards the east, a sequence may be observed as follows:

‘4. Boulder-clay with northern erratics and shells.

“3. Sands and gravels with northern erratics and shells.

“2. Boulder-clay with northern erratics and shells.

“1. Boulder-clay with Welsh erratics and no shells.

“A similar succession is to be seen in the Vale of
Clwyd. ‘The interpretation is clear: In the early stages
of glaciation the Welsh ice spread without hindrance to,
and laid down, bed No. 1; then the northern ice came
down, bringing its typical erratics and the scourings of
the sea-bottom, and laid down the variable series of clays,
sands, and gravels which constitute Nos. 2, 8, and 4 of
the section.

“In the Vale of Clwyd an additional interest is imparted
to the study of the drift from the circumstance that the
remains of man haye been found in deposits in caves sealed
with drift-beds. The best example is the Cae Gwyn caves,

Fig. 42.—The Cefn Cave, in Vale of Clwyd. (Trimmer.) a, Entrance; 6, mud
with pebbles and wood covered with stalagmite ; ¢, mud, bones, and angular
fragments of limestone; d@, sand and silt, with fragments of marine shells ;
é, fissure ; f, northern drift; g, cave cleared of mud; A, river Elwy, 100 feet
below ; 2, limestone rock.

in which flint implements and the bones and teeth of va-
rious extinct animals were found embedded in ‘ cave-

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 149

earth’ which was overlaid by bedded deposits of shell-
bearing drift, with erratics of the northern type.

“Tt has been supposed that the drift-deposits were ma-
rine accumulations; but it is inconceivable that the cave
could ever have been subjected to wave-action without the
complete scouring out of its contents.

“To resume the delineation of the limits of the great
Irish Sea Glacier: From the Vale of Clwyd the boundary
runs along the range of hills parallel to the estuary of the
Dee at an altitude of about nine hundred feet. As it 1s
traced to the southeast it gradually rises, until at Frondeg,
a few miles to the northward of the embouchure of the
Vale of Llangollen, it is at a height of 1,450 feet above
sea-level. ‘Thence it falls to 1,150 feet at Gloppa, three
miles to the westward of Oswestry, and this is the most
southerly point to which it has been definitely traced on
the Welsh border, though scattered boulders of northern
rocks are known to occur at Church Stretton.

“ Along the line from the Vale of Clwyd to Oswestry the
boundary is marked by a very striking series of moraine-
mounds. ‘They occur on the extreme summits of lofty
hills in a country generally almost driftless, and their ap-
pearance is so unusual that one—Moel-y-crio—at least has
been mistaken for an artificial tumulus. The limitation
of the dispersal of northern erratics by these mounds is
very clear and sharp; and Mackintosh, in describing those
at Frondeg, remarked that, while no northern rocks ex-
tended to the westward of them, so no Welsh erratics could
be found to cross the line to the eastward. There are
Welsh erratics in the low grounds of Cheshire and Shrop-
shire, but their distribution 1s sporadic, and will be ex-
plained in a subsequent section.

“ Having thus followed around the edges of this glacier,
it remains to describe its termination. It isclear that the
ice must have forced its way over the low water-shed
between the respective basins of the Dee and the Severn.

150 MAN AND THE GLACIAL PERIOD.

So soon as this ridge (less than 500 feet above the sea) is
crossed, we find the deposits laid down by the glacier
change their character, and sands and gravels attain a
great predominance.* Near Bridgenorth, and at other
places, hills composed of such materials attain an altitude
of 200 feet. From Shrewsbury via Burton, and thence,
in a semicircular sweep, through Bridgenorth and Enville,
there is an immense concentration of boulders and peb-
bles, such as to justify the designation of a terminal mo-
raine. ‘To the southward, down the valley of the Severn,
existing information points to the occurrence merely of
such scattered pebbles as might have been carried down
by floods. In the district lying outside this moraine there
is a most interesting series of glacial deposits and of bould-
ers of an entirely different character. (See map.)

“ From the neighbourhood of Lichfield, through some
of the suburbs of Birmingham, and over Frankley Hill and
the Lickey Hills to Bromsgrove, there is a great accumu-
lation of Welsh erratics, from the neighbourhood, prob-
ably, of Arenig Mawr.

“The late Professor Carvill Lewis suggested that these
Arenig rocks might have been derived from some adjacent
outcrop of Paleozoic rocks—a suggestion having its justi-
fication in the discoveries that had been made of Cum-
brian rocks in the Midlands. ‘To test the matter, an ex-
cavation was made at a point selected on Frankley Hill,
and a genuine boulder-clay was found, containing erratics
of the same type as those found upon the surface.

“The explanation has since been offered that this bould-
er-clay was a marine deposit laid down during a period
of submergence.t Apart from the difficulty that the
boulder-clay displays none of the ordinary characteristics
of a marine deposition, but possesses a structure, or rather

* Mackintosh, Q. J. G. S.
+ Proceedings of the Birmingham Philosophical Society, vol. vi,
Part I, p. 181.

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 151

absence of structure, in. many respects quite inconsistent
with such an origin, and contains no shells or other remains
of marine creatures, it must be pointed out that no theory
of marine flotation will explain the distribution of the
erratics, and especially their concentration in such num-
bers at a station sixty or seventy miles from their source.
“Upon the land-ice hypothesis this difficulty disappears.
During the early stages of the Glacial period the Welsh
ice had the whole of the Severn Valley at its mercy, and a
great glacier was thrust down from Arenig, or some other
point in central Wales, having an initial direction, broadly
speaking, from west to east. This glacier extended across
the valley of the Severn, sweeping past the Wrekin, whence
it carried blocks of the very characteristic rocks to be
lodged as boulders near Lichfield; and it probably formed
its terminal moraine along the line indicated. (See lozenge-
shaped marks on the map.) As the ice in the north gath-
ered volume it produced the great Irish Sea Glacier, which
pressed inland and down the Vale of Severn in the manner
I have described, and brushed the relatively small Welsh
stream out of its path, and laid down its own terminal
moraine in the space between the Welsh border and the
Lickey Hills. It seems probable that the Welsh stream
came mainly down the Vale of Llangollen, and thence to
the Lickey Hills. Boulders of Welsh rocks occur in the
intervening tract by ones and twos, with occasional large
clusters, the preservation of any more connected trail
being rendered impossible by the great discharge of water
from the front of the Irish Sea Glacier, and the distrib-
uting action of the glacier itself. :

_ “ Within the area in England and Wales covered by the
Trish Sea Glacier all the phenomena point to the action of
land-ice, with the inevitable concomitants of sub-glacial
streams, extra-morainic lakes, etc. There is nothing to
suggest marine conditions in any form except the occur-
rence of shells or shell fragments; and these present so

152 MAN AND THE GLACIAL PERIOD,

many features of association, condition, and position in-
consistent with what we should be led to expect from a
study of recent marine life, that conchologists are unani-
mous in declaring that not one single group of them is on
the site whereon the shells lived. It is a most significant
fact—one out of a hundred which could be cited did space
permit—that in the ten thousand square miles of, as it is
supposed, recently elevated sea-bottom, not a single ex-
ample of a bivalve shell with its valves in apposition has
ever been found! Nor has a boulder or other stone been
found encrusted with those ubiquitous marine parasites,
the barnacles.

“The evidences of the action of land-ice within the area
are everywhere apparent in the constancy of direction of—
(1.) Striz upon rock surfaces. (2.) The terminal curva-
ture of rocks. (3.) The ‘pull-over’ of soft rocks. (4.)
The transportal of local boulders. (5.) The orientation of
the long axes of large boulders. (6.) The false bedding
of sands and gravels. (7.) The elongation of drift-hills.
(8.) The relations of ‘crag and tail.’ There is a similar
general constancy, too, in the directions of the strize upon
large boulders. Upon the under side they run longitudi-
nally from southeast (or thereabouts) to northwest, while
upon the upper surface they originate at the opposite
end, showing that the scratches on the under side were
produced by the stone being dragged from northwest to
southeast, while those on the top were the product of
the passage of stone-laden ice over it in the same direc-
tion.

“Such an agreement cannot be fortuitous, but must be
attributed to the operation of some agent acting in close
parallelism over the whole area. To attribute such regu-
larity to the action of marine currents is to ignore the
most elementary principles of marine hydrology. Ice-
bergs must, in the nature of things, be the most erratic
of all agents, for the direction of drift is determined—

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 153

among other varying factors—by the draught of the berg.
A mass of small draught will be carried by surface cur-
rents, while one of greater depth will be brought within
the influence of under-currents; and hence it not infre-
quently happens that while floe-ice is drifting, say, to the
southeast, giant bergs will go crashing through it to the
northwest. There are tidal influences also to be reckoned
with, and it is matter of common knowledge that flotsam
and jetsam travel back and forth, as they are alternately
affected by ebb and flood tide.

“ Bearing these facts in mind, it is surely too much to
expect that marine ice should transport boulders (how it
picked up many of them also requires explanation) with
such unfailing regularity that it can be said without chal-
lenge,* ‘boulders in this district [South Lancashire and
Cheshire] never occur to the north or west of the parent
rock.’ The same rule applies without a single authentic
exception to the whole area covered by the eastern branch
of the Irish Sea Glacier; and hence it comes about that
not a single boulder of Welsh rock has ever been 1ecorded
from Lancashire.

“The Solway Glacier.—'The pressure which forced
much of the Irish Sea ice against the Cumbrian coast-line
caused, as has been described, a cleavage of the flow near
Ravenglass, and, having followed the southerly branch to
its termination in the midlands, the remaining moiety de-
mands attention.

“The ‘ easting ’ motion carried it up the Solway Frith,
its right flank spreading over the low plain of northern
Cumberland, which it strewed with boulders of the well-
known ‘syenite’ (granophyre) of Buttermere. When this
ice reached the foot of the Cross Fell escarpment, it suf-
fered a second bifurcation, one branch pushing to the
eastward up the valley of the Irthing and over into Tyne-

* Brit. Assoc. Report, 1890, p. 343.

154 MAN AND THE GLACIAL PERIOD.

side, and the other turning nearly due southward and
forcing its way up the broad Vale of Eden.

‘Under the pressure of an enormous head of ice, this
stream rose from sea-level, turned back or incorporated
the native Cumbrian Glacier which stood in its path, and,
having arrived almost at the water-shed between the
northern and the southern drainage, it swept round to
the eastward and crossed over the Pennine water-shed ;
not, however, by the lowest pass, which is only some 1,400
feet above sea-level, but by the higher pass of Stainmoor,
at altitudes ranging from 1,800 to 2,000 feet. The lower -
part of the course of this ice-flow is sufficiently well char-
acterised by boulders of the granite of the neighbourhood
of Dalbeattie in Galloway; but on its way up the Vale of
Eden it gathered several very remarkable rocks and posted
them as way-stones to mark its course. One of these
rocks, the Permian Brockram, occurs nowhere in situ
at altitudes exceeding 700 feet, yet in the course of its
short transit it was lifted about.a thousand feet above its
source. The Shap granite (see radiant point on map)
is on the northern side of the east and west water-sheds
of the Lake District, and reaches its extreme elevation,
(1,656 feet) on Wasdale Pike; yet boulders of it were
carried over Stainmoor, at an altitude of 1,800 feet liter-
ally by tens of thousands.

“This Stainmoor Glacier passed directly over the Pen-
nine chain, past the mouths of several valleys, and into
Teesdale, which it descended and spread out in the low
grounds beyond. Pursuing its easterly course, it abutted
upon the lofty Cleveland Hills and separated into two
streams, one of which went straight out to sea at Hartle-
pool, while the other turned to the southward and flowed
down the Vale of York, being augmented on its way by
tributary glaciers coming down Wensleydale. The final
melting seems to have taken place somewhere a little to
the southward of York; but boulders of Shap granite by

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 155

which its extension is characterised have been found as
far to the southward as Royston, near Barnsley.

“The other branch of the Solway Glacier—that which
travelled due eastward—passed up the valley of the Ir-
thing, and over into that of the Tyne, and out to sea at
Tynemouth. It carried the Scottish granites with it, and
tributary masses joined on either hand, bringing charac-
teristic boulders with them.

“The fate of those elements of the Solway Frith Gla-
cier which reached the sea is not left entirely to conject-
ure. ‘The striated surfaces near the coast of Northum-
berland indicate a coastwise flow of ice from the north-
ward—probably from the Frith of Forth—and the gla-
clers coming out from the Tyne and Tees were deflected
to the southward.

“There is conclusive evidence that this ice rasped the
cliffs of the Yorkshire coast and pressed up into some of
the valleys. Where it passed the mouth of the Tees near
Whitby it must have had a height of at least 800 feet, but
farther down the coast it diminished in thickness. It
nowhere extended inland more than a mile or two, and
for the most part kept strictly to the coast-line. Along
the whole coast are scattered erratics derived from Gal-
loway and the places lying in the paths of the glaciers.
In many places the cliffs exhibit signs of rough usage,
the rocks being crumpled and distorted by the violent
impact of the ice. At Filey Brigg a well-scratched sur-
face has been discovered, the striation being from a few
degrees east of north.

“ At Speeton the evidence of ice-sheet or glacier-work is
of the most striking character. On the top of the cliffs of
Cretaceous strata a line of moraine-hills has been laid down,
extending in wonderful perfection for a distance of six
miles. They consist of a mixture of sand, gravel, and a
species of clay-rubble, with occasional masses of true bould-
er-clay, the whole showing the arched bedding so char-

156 MAN AND THE GLACIAL PERIOD.

acteristic of such accumulations. At the northerly end
the moraine keeps close to the edge of the chalk cliffs,
which are there 400 feet high, and the hills are frequently
displayed in section; but as the elevation of the cliffs de-
clines they fall back from the edge of the cliffs and run
quite across the headland of Flamborough, and are again ~

13

SPEETON
CLIFFS
Ahh BUCKTON CLIFFS 49

= Sanwick 10
ow jog Thornwick \
Rea North Sea Landing
oe S

~~ Brail Head
“pa > 150
825 STATION
B Stottle Bank 9
300 By \ ce
250 >¥ Selwicks
= b AN 125 4.
=H & A
zh o”° SHigh Stacks §

3 y << —

4 M

200 STATIONED j we THE MATRON’
i 5 Old Falts

AH 125
150 : %
EI
H 9 BE
ae 40 pike rag
125 1004 100775 123.6
BRIDLINGTON@_“ Buried Clift 4.
-90 50 LS
yy

S
L

50
Potter Hill 3

25 2 SCALE ee —? mites,

Fig. 43.—Moraine between Speeton and Flamborough (Lamplugh).

exposed in section in Bridlington Bay. One remarkable
and significant fact is pointed out, namely, that behind
this moraine, within half a mile and at a lower level, the
country is almost absolutely devoid of any drift whatever.

“The interpretation of these phenomena is as follows:

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 157

When the valley-glaciers reached the sea they suffered the
deflection which has been mentioned, partly as the result
of the interference of ice from the east of Scotland, but
also influenced directly by the cause which operated upon
the Scottish ice and gave direction to it—that is, the im-
pact of a great glacier from Scandinavia, which almost
filled the North Sea, and turned in the eastward-flowing
ice upon the British coast.

“Tt is easy to see how this pressure must have forced the
glacier-ice against the Yorkshire coast, but vertical chalk
cliffs 400 feet in height are not readily surmounted by ice
of any thickness, however great, and so it coasted along
and discharged its lateral moraine upon the cliff-tops. As
the cliffs diminished in height we find the moraine farther
inland, and, as I have pointed out, the ice completely over-
rode Flamborough Head. Amongst the boulders at Flam-
borough are many of Shap granite, a few Galloway gran-
ites, a profusion of Carboniferous rocks, brought by the
Tyne branch of the Solway Glacier as well as by that of
Stainmoor, and, besides many torn from the cliffs of York-
shire, a few examples of unquestionable Scandinavian rocks,
such as the well-known Rhomben-porphyr. It is impor-
tant to note that about ten to twenty miles from the York-
shire coast there is a tract of sea-bottom called by trawl-
ers ‘the rough ground,’ in allusion to the fact that it
is strewn with large boulders, amongst which are many of
Shap granite. This probably represents a moraine of the
Teesdale Glacier, laid down at a time when the Scandi-
navian Glacier was not at its greatest development.

“On the south side of Flamborough Head the ‘ buried
cliff’ previously alluded to occurs. The configuration of
the country shows—and the conclusion is established by
numerous deep-borings—that the pre-glacial coast-line
takes a great sweep inland from here, and that the plain
of Holderness is the result of the banking-up of an im-
mense thickness of glacial débris. In the whole country

158 MAN AND THE GLACIAL PERIOD.

reviewed, from Tynemouth to Bridlington, wherever the
ice came on to the land from the seaward, it brought in
Shells and fragmentary patches of the sea-bottom in-
volved in its ground moraine. Space does not permit of
a detailed description of the several members of the York-
shire Drift, and I pass on to deal in a general way with
the glacial phenomena of the eastern side of Eng-
land. :
“The Hast Anghan Glacier.—The influence of the
Scandinavian ice is clearly seen in the fact that the entire

ice-movement down the east coast south of Bridlington .

was all from the seaward. Clays, sands, and gravels, the
products of a continuous mass of land-ice coming from
the northeast are spread over the whole country, from the
Trent to the high grounds on the north of London over-
looking the Thames. |

“The line of extreme extension of these drift-deposits
runs from Finchley (near London), in the south across
Hertfordshire, through Cambridgeshire, with outlying
patches at Gogmagog and near Buckingham, and north-
westward over a large portion of Leicestershire into the
upper waters of the Trent, embracing the elevated region
of Paleozoic rocks at Charnwood Forest, near Leices-
ter.

“‘ Reserving the consideration of the very involved ques-
tions connected with the drifts of the upper part of the
Trent Valley, I may pass on to join the phenomena of the
southeastern counties with those at Flamborough Head.
From Nottinghamshire the limits of the drift of the Hast
Anghan Glacier seem to run in a direction nearly due
west to east, for the great odlitic escarpment upon which
Lincoln Cathedral is built is absolutely driftless to the
northward of the breach about Sleaford. However, along
the western flank of the odlitic range true boulder-clay
occurs, bordering and doubtless underlying the great fen-
tract of mid-Lincolnshire; and the great Lincolnshire

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 159

Wolds appear to have been completely whelmed beneath
the ice.

“The most remarkable of the deposits in this area is
the Great Chalky Boulder-Clay, which consists of clay con-
taining much ground-up chalk, and literally packed with
well-striated boulders of chalk of all sizes, from minute
pebbles up to blocks a foot or more in diameter. Associ-
ated with them are boulders of various foreign rocks, and
many flints in a remarkably fresh condition, and still re-
taining the characteristic white coat, except where par-
tially removed by glacial attrition.

“One of the perplexing features of the glacial phenom-
ena in the eastern counties of England is the extension
of true chalky boulder-clay to the north London heights
at Finchley and elsewhere; for only the faintest traces are
to be found in the gravel deposits of the Thames Valley
of any wash from such a deposit, or from a glacier carry-
ing such materials.

“Tt has been suggested that the deposit may have been
laid down in an extra-morainic lake, or in an extension of
the North Sea, but these suggestions leave the difficulty
just where it was. If a lake or sea could exist without
shores, a glacier-stream might equally dispense with banks.
Within the area of glaciation, defined above, abundant
evidence of the action of land-ice is obtainable, though
striated surfaces are extremely rare—a fact attributable to
the softness of the chalk and clays which ovcupy almost
the whole area. Well-striated surfaces are found on the
harder rocks, as, for example, on the odlitic hmestone at
Dunston, near Lincoln.

“Mr. Skertchly has remarked that the proofs of the
action of land-ice are irrefragable. The Great Chalky
Boulder-Clay covers an area of 3,000 square miles, and at-
tains an altitude of 500 feet above the sea-level, thus be-
speaking, if the product of icebergs, ‘an extensive gath-

ering-ground of chalk, having an elevation of more than
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MAN AND THE GLACIAL PERIOD.

160

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 16]

500 feet. But where is it? Certainly not in Western
Europe, for the chalk does not attain so great an elevation
except in a few isolated spots.’ *

“Tt has been further pointed out by Mr. Skertchly, that
the condition of the flints in this deposit furnishes strong
evidence that they could not have been carried by floating
ice nor upon a glacier, for, in either of the latter events,
there must have been some exposure to the weather, which,
as he remarks, would have rendered them worthless to the
makers of gun-flints, whereas they are now regularly col-
lected for their use.

“The way in which the boulder-clay is related to the
rocks upon which it rests is a conclusive condemnation of
any theory of floating ice; for example, where it rests up-
on Oxford Clay, it contains the fossils characteristic of
that formation, as it is largely made up of the clay itself.
The exceptions to this rule are as suggestive as those cases
which conform to it. Each outcrop yields material to the
boulder-clay to the southwestward, showing a pull-over
from the northeast.

“One of the most remarkable features of the drift of
this part of England is the inclusion of gigantic masses of
rock transported for a short distance from their native
outcrop, very often with so small a disturbance that they
have been mapped as in situ. Examples of chalk-masses
800 feet in length, and of considerable breadth and thick-
ness, have been observed in the cliffs near Cromer, in Nor-
folk, but they are by no means restricted to situations
near the coast. One example is mentioned in which
quarrying operations had been carried on for some years
before any suspicion was aroused that it was merely an
erratic. The huge boulders were probably dislodged from
the parent rock by the thrust of a great glacier, which first
crumbled the beds, then sheared off a prominent fold and

* Geikie’s Great Ice Age, p. 360.

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MAN AND THE GLAC

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ANCIENT GLACIERS IN EASTERN HEMISPHERE. 163

carried it along. This explanation we owe to Mr. Clement
Reid.* The drift-deposits of this region frequently con-
tain shells, but they rarely constitute what may be termed
a consistent fauna, usually showing such an association as
could only be found where some agent had been at work
gathering together shells of different habitats and geologi-
cal age.

“Attempts have been made to correlate the deposits
over the whole area, but with very indifferent success. A
consideration of the consequences of the invasion of the
country by an ice-stream from the northeast will prepare
us for any conceivable complication of the deposits.

“The main movement was against the drainage of the
country, so that the ice-front must have been frequently
in water. There would be aqueous deposition and ero-
sion; the kneading up of morainic matter into ground-
moraine ; irregularities of distribution and deposition due
to ice floating in an extra-morainic lake; flood-washes at
different points of overflow; and other confusing causes,
which make it rather matter for surprise that any order
whatever is traceable.

“T now turn to the valley of the Trent. We find that
it occupies such a position that it would be exposed, suc-
cessively or simultaneously, to the action of ice-streams
of most diverse origin. I have shown that the area to the
westward of Lichfield was invaded at one period by a
Welsh glacier, and at a subsequent one by the Irish Sea
Glacier, and both of these streams entered the valley of
the Trent or some of its affluents. From the eastward,
again, the great North Sea Glacier encroached in like man-
ner, carrying the Great Chalky Boulder-Clay even into the
drainage area of the westward-flowing rivers near Cov-
entry.

* See Geology of the Country around Cromer, and Geology of
Holderness, Memoirs of Geological Survey of England and Wales.

164 MAN AND THE GLACIAL PERIOD.

“The glacial geology of the Trent Valley from Burton
to Nottingham has been ably dealt with by Mr. R. M.
Deeley,* who recognises a succession which may be gener-
alised as follows: (1.) A lower series containing rocks de-
rived from the Pennine chain; (2.) A middle series con-
taining rocks from the eastward (chalky boulder-clay,
etc.); and (3.) An upper series with Pennine rocks. Mr.
Deeley thinks the Pennine dédris may have been brought
by glaciers flowing down the valleys of the Dove, the Wye,
and the Derwent; but, while recognising the importance
of the testimony adduced, especially that of the boulders,
I am compelled to reserve judgment upon this point until —
something like moraines or other evidences of local glaciers
can be shown in those valleys. In their upper parts there
is not a sign of glaciation. Some of the deposits de-
scribed must have been laid down by land-ice; while the
conformation of the country shows that during some stages
of glaciation a lake must have existed into which the dif-
ferent elements of the converging glaciers must have pro-
jected. ‘This condition will account for the remarkable
commingling of boulders observed in some of the deposits.
Welsh, Cumbrian, and Scottish rocks occur in the western
portion: of the Trent Valley. ‘The overflow of the extra-
morainic lake would find its way into the valleys of the
Avon and Severn, and may be taken to account for the
abundance of flints in some of the gravels.

“ The Isle of Man.—This little island in mid-seas con-
stituted in the early stages of the Glacial epoch an inde-
pendent centre of glaciation, and from some of its valleys
ice-streams undoubtedly descended to the sea; but with
the growth of the great Irish Sea Glacier the native ice
was merged in the invading mass, and at the climax of the
period the whole island was completely buried, even to its
highest peak (Snae Fell, 2,054 feet), beneath the ice. The

* Quarterly Journal Geological Society, vol. xlii, p. 437.

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 165

effects of this general glaciation are clearly seen in the
mantle of unstratified drift material which overspread the
hills; in the mouwtonnée appearance of the entire island ;
and in the transport of boulders of local rocks. The
striations upon rock surfaces show a constancy of direc-
tion in agreement with the boulder transport which can
be ascribed to no other agency than a great continuous
sheet of such dimensions as to ignore minor hills and
valleys.

“The disposition of the striz is equally conclusive, for
we find that on a stepped escarpment of limestone both
the horizontal and the vertical faces are striated contin-
uously and obliquely from the one on to the other, showing
that the ice had a power of accommodating itself to the
surface over which it passed that could not be displayed
by floating ice. There is a remarkable fact concerning
the distribution of boulders on this island which would
strike the most superficial observers, namely, that foreign
rocks are confined to the low grounds. It might be
argued that the local ice always retained its individuality,
and so kept the foreign ice with its characteristic boulders
at bay. But, apart from the a priori improbability of so
small a hill-cluster achieving what the Lake District
could not accomplish, the fact that Snae Fell, an isolated
conical hill, is swathed in drift from top to bottom, is
quite conclusive that the foreign ice must have got in.
Why, then, did it carry no stones with it? The following
suggestion I make not without misgivings, though there
are many facts to which I might appeal that seem strong-
ly corroborative :

“The hilly axis of the island runs in a general north-
east and southwest direction, and it rises from a great
expanse of drift in the north with singular abruptness,
some of the hills being almost inaccessible to a direct ap-
proach without actual climbing. I imagine that the ice
which bore down upon the northern end of the island

166 MAN AND THE GLACIAL PERIOD.

was, so far as its lower strata were concerned,-unable to
ascend so steep an acclivity, and was cleft, and flowed to
right and left. The upper ice, being of ice-sheet origin,
would be relatively clean, and this flowing straight over
the top of the obstruction would glaciate the country
with such material as was lying loose upon the ground or
could be dislodged by mere pressure. It would appear
from published descriptions that the Isle of Arran offers
the same problem, and I would suggest the application of
the same solution to it.

“ Marine shells occur in the Manx drift, but only in
such situations as were reached by the ice laden with
foreign stones. They present similar features of associ-
ation of shells of different habitat, and perhaps of geo-
logical age, to those already referred to as being com-
mon characteristics of the shell-faunas of the drift of the
mainland. Four extinct species of mollusca have been
recognised by me in the Manx drift.

“The Manx drift is of great interest as showing, per-
haps better than any locality yet studied, those features
of the distribution of boulders of native rocks which at-
test so clearly the exclusive action of land-ice. There
are in the island many highly characteristic igneous
rocks, and I have found that boulders of these rocks
never occur to the northward of the parent mass, and
very rarely in any direction except to the southwest.

‘“¢ Cumming observed in regard to one rock, the Foxdale
granite, that whereas the highest point at which it occurs
in situ was 657 feet above sea-level, boulders of it occurred
in profusion within 200 feet of the summit of South Bar-
rule (1,585 feet), a hill two miles only, in a southwesterly
direction, from the granite outcrop.

“They also occur on the summit of Cronk-na-Irrey-
Lhaa, 1,449 feet above sea-level. The vertical uplift has
been 728 and 792 feet respectively.

“In the low grounds of the north of the island a finely

ANCIENT GLACIERS IN HASTERN HEMISPHERE. 167

developed terminal moraine extends in a great sweep
so as to obstruct the drainage and convert thousands
of acres of land into lake and morass, which is only now
yielding to artificial drainage. Many fine examples of
drumlin and esker mounds occur at low levels in differ-
ent parts of the island; and it was remarked nearly fifty
years ago by Cumming, that their long axes were parallel
to the direction of ice-movement indicated by the striated
surfaces and the transport of boulders.

“The foreign boulders are mainly from the granite
mountains of Galloway, but there are many flints, pre-
sumably from Antrim, a very small number of Lake Dis-
trict rocks, and a remarkable rock containing the excess-
ively rare variety of hornblende, Riebeckite. This has
now been identified with a rock on Ailsa Crag, a tiny
islet in the Frith of Clyde; and a Manx geologist, the
Rey. S. N. Harrison, has discovered a single boulder of
the highly characteristic pitchstone of Corriegills, in the
Isle of Arran.

“ The So-called Great Submergence.

“Tt may be convenient to adduce some additional facts
which render the theory of a great submergence of the
country south of the Cheviots untenable.

“The sole evidence upon which it rests is the occur-
rence of shells, mostly in an extremely fragmentary condi-
tion, in deposits occurring at various levels up to about
1,400 feet above sea-level: <A little space may profitably
be devoted to a criticism of this evidence.

“ Moel Tryfaen (‘ The Hillof the Three Rocks ’).—This
celebrated locality is on the first rise of the ground between
the Menai Straits and the congeries of hills constituting
‘ Snowdonia’; and when we look to the northward from
the top of the hill (1,350 feet) we see the ground rising
from the straits in a series of gentle undulations whose
smooth contours would be found from a walk across the

168 MAN AND THE GLACIAL PERIOD.

country to be due to the thick mask of glacial deposits
which obliterates the harsher features of the solid rocks.

“The deposits on Moel Tryfaen are exposed in a slate-
quarry on the northern aspect of the hill near the summit,
and consist of two wedges of structureless boulder-clay,
each thinning towards the top of the hill. ‘The lower mass
of clay, wherever it rests upon the rock, contains streaks
and irregular patches of eccentric form, of sharp, perfectly
angular fragments of slate; and the underlying rock may
be seen to be crushed and broken, its cleavage-laminz
being thrust over from northwest to southeast—that is,
up-hill. The famous ‘shell-bed’ is a thick series of
sands and gravels interosculated with the clays on the
slope of the hill, but occupying the entire section above the
slate towards the top. The bedding shows unmistakable
signs of the action of water, both regular stratification and
false bedding being well displayed. The stones occurring
in the clays are mainly if not entirely Welsh, including
some from the interior of the country, and they are not in-
frequently of large size—two or three tons’ weight—and
well scratched.

“'The stones found in the sands and gravels include a
great majority of local rocks, but besides these there have
been recorded the following :

Highest | Minimum
Rock. Source, _point uplift
in situ. in feet.
Gara ercs del ee chen Eskdale, Cumberland...) 1,286 64
GATTO sare aes soho cnctens Criftely Gallowayoce as- eae se
IU Roeser Sears satiate s wcens ALBAN ER Gaudw op 656 1,000 350
To these I can add:
Granophyrestee sa-5ee Buttermere, Cumber-
anid <5 Pay beieGie yee ene eo
UENO cies che Sas ace ye Ailsa Craig, Frith of
Clydeiss.: se See 1,097 2538

* The altitude at which this rock occurs on Ailsa Craig has not
been announced, so I have put it as the extreme height of the island.

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 169

“ The shells in the Moel Tryfaen deposit have been fully
described, so far as the enumeration of species and rela-
tive frequency are concerned, but little has been said as to
their absolute abundance and their condition. The shells
are extremely rare, and during a recent visit a party of
five persons, in an assiduous search of about two hours, suc-
ceeded in finding five whole shells and about two ounces of
fragments. ‘The opportunities for collecting are as good
as could be desired. ‘The sections exposed have an aggre-
gate length of about a quarter of a mile, with a height
varying from ten to twenty feet of the shelly portion; and
besides this there are immense spoil-banks, upon whose
rain-washed slopes fossil-collecting can be carried on under
the most favorable conditions.

‘“] would here remark, that the occurrence of small
seams of shelly material of exceptional richness has im-
pressed collectors with the idea that they were dealing with
a veritable shell-bed, when the facts would bear a very dif-
ferent interpretation. A fictitious abundance is brought
about by a process of what may be termed ‘ concentration,’
by the action of a gently flowing current of water upon
materials of different sizes and different specific gravities.
Shells when but recently vacated consist of materials of
rather high specific gravity, penetrated by pores contain-
ing anima! matter, so that the density of the whole mass
is far below that of rocks in general, and hence a current
too feeble to move pebbles would yet earry shells. ITllus-
trations of this process may be observed upon any shore
in the concentration of fragments of coal, corks, or other
light material.

“ Regarding the interpretation of these facts: The com-
monly received idea is, that the beds were laid down in the
sea during a period of submergence, and that the shells
lived, not perhaps on the spot, but somewhere near, and
that the terminal curvature of the slate was produced by
the grounding of icebergs which also brought the boul-

170 MAN AND THE GLACIAL PERIOD.

ders. But if this hypothesis were accepted, it would be
necessary to invest the flotation of ice with a constancy of
direction entirely at variance with observed facts, for the
phenomena of terminal curvature is shown with perfect
persistence of direction wherever the boulder-clay rests
upon the rock; and, further, there is the highly signifi-
cant fact, that neither the sands and gravels nor the rock
upon which they rest show any signs of disturbance or
contortion, such as must have been produced if floating
ice had been an operative agent.

“The uplift of foreign rocks is equally significant; and
when we take into account the great distances from which
they have been borne and the frequency with which such
an operation must have been repeated, the inadequacy be-
comes apparent of Darwin’s ingenious suggestion, that it
might have been effected by a succession of uplifts by
shore-ice during a period of slow subsidence; while the
character and abundance of the molluscan remains invest
with a species of irony the application of the term ‘ shell-
bed’ to the deposit. :

“T now turn to the alternative explanation (see ante, p.
145), viz., that the whole of the phenomena were produced
by a mass of land-ice which was forced in upon Moel Try-
faen from the north or northwest, overpowering any Welsh
ice which obstructed its course. This view is in harmony
with the observations regarding the ‘ terminal curvature’
of the slates, the occurrence of sharp angular chips of slate
in the boulder-clay, and the coincidence of direction of
these indications of movement with the carry of foreign
stones. The few shells and shell-crumbs in the sands and
gravels would, upon this hypothesis, be the infinitesimal
relics of huge shell-banks in the Irish Sea which were
destroyed by the glacier and in part incorporated in its
ground-moraine or involved in the ice itself. The sands
and gravels would represent the wash which would take
place wherever, by the occurrence of a ‘nunatak’ or by

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 171

approach to the edge of the ice, water could have a free
escape. ,

“Two principal objections have been urged to the land-
ice explanation of the Moel Tryfaen deposits. An able
critic asks, ‘ Can, then, ice walk up-hill?’ To this we
answer, Given a sufficient.‘ head’ behind it, and ice can
certainly achieve that feat, as every roche moutonnée
proves. Ifit be granted that ice on the small scale can
move up-hill, there is no logical halting-place between the
uplift of ten or twenty feet to surmount a roche mouton-
née, and an equally gradual elevation to the height of Moel
Tryfaen. Furthermore, the inland ice of Greenland is
known to extrude its ground-moraine on the ‘ weather-
side’ of the nunataks, and the same action would account
for the material uplifted on Moel Tryfaen.

“ The second objection brought forward was couched in
somewhat these terms: ‘ If the Lake District had its ice-
sheet, surely Wales had one also. Could not Snowdonia
protect the heart of its own domain?’ Of course, Wales
had its ice-sheet, and the question so pointedly raised by
the objector needs an answer; and though it is merely a
question of how much force is requisite to overcome a cer-
tain resistance (both factors being unknown), still there
are features in the case which render it specially interest-
ing and at the same time comparatively easy of explana-
tion. It seems rather like stating a paradox, yet the fact
is, that it was the proximity of Snowdon which, in my
opinion, enabled the foreign ice to invade Wales at that
point.

“A glance at the map will show that the ‘radiant point’
of the Welsh ice was situated on or near Arenig Mawr, and
that the great mass of Snowdon stands quite on the pe-
riphery of the mountainous regions of North Wales, so
that it would oppose its bulk to fend off the native ice-
sheet and prevent it from extending seaward in that di-
rection.

172

RADIANT POINT

Moel Tryfaen

\“S
\S
WY
WO
WY

MAN AND THE GLACIAL PERIOD.

WHEEL

FOREIGN HGES

(65

1,350

Scale, 1’= 8,000 Ft. Vertical; 12 Miles Horizontal.
Fig. 46.—Section across Wales to show the relations of native to foreign ice.

“‘ As a consequence, the only Welsh
ice in position to obstruct the onward
march of the invader would be such
trifling valley-glaciers as could form
on the western slopes of Snowdon it-
self.

“The peak of Snowdon is 3,570

feet above sea-level, and Arenig Mawr,
2,817 feet high, is eighteen miles to
the eastward, and a broad, deep valley
with unobstructed access to Cardigan
Bay intervenes; so, if any ice from
the central mass made its way over
the Snowdonian range, it performed
a much more surprising feat than that
involved in the ascent of Moel Tryfaen
from the westward.
_ “The profile shows in diagrammat-
ic form the probable. relations of the
foreign to the native ice at the time
when the Moel Tryfaen deposits were
laid down.

“ Hrom what has been said regard-
ing the great glaciers, it would seem
that ice advanced upon the land from
the seaward in several parts of. the
coast of England, Wales, and the Isle
of Man. Now, it is in precisely those
parts of the country, and those alone,
that the remains of marine animals
occur in the glacial deposits. If the
dispersal of the shells found in the
drift had been effected by the means
I have suggested, it would follow, as
an inevitable consequence, that wher-
ever shells occur there should also

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 173

be boulders which have been brought from beyond the
sea. ‘This I find to be the case, and in two instances the
discovery of shells was preliminary to the extension of the
boundaries of the known distribution of boulders of trans-
marine origin.

“The officers of the Geological Survey some years ago
observed the occurrence of ‘obscure fragments of marine
shells ’ in a deposit at Whalley, Lancashire, in which they
could find only local rocks. One case such as this would
be fatal to the theory of the remanié origin of the shells,
but on visiting the section with Mr. W. A. Downham, I
found, amongst the very few stones which occurred in the
shell-bearing sand at the spot indicated, two well-marked
examples of Cumbrian volcanic rocks, and, at a little dis-
tance, large boulders of Scottish granites.

“The second case is more striking. The announcement
was made that shells had been found on a hill called Gloppa,
near Oswestry, in Shropshire, and, as it lay about five miles
to the westward of Mackintosh’s boundary of the Irish Sea
Glacier, and therefore well within the area of exclusively
Welsh boulders, it furnished an excellent opportunity of
putting the theory to the test. An examination of the
boulders associated with the shells showed that the whole
suite of Galloway and Cumbrian erratics such as belong to
the Irish Sea Glacier were present in great abundance.
Not only this, but in the midst of the series of shell-bear-
ing gravels I observed a thin lenticular bed of greenish
clay, which upon examination was found to be crowded
with well-scratched specimens of Welsh rocks; but neither
a morsel of shell nor a single pebble of a foreign rock
could be found, either by a careful examination in the
field or by washing the clay at home, and examining with
a lens the sind and stones separated out.

“The fact that predictions such as these have been veri-
fied affords a very striking corroboration of the theory put
forward; and, though shells cannot be found in every

174 MAN AND THE GLACIAL PERIOD.

deposit in which they might, ex hypothesi, be found, yet
the strict limitation of them to situations which conform
to those assigned upon theoretical grounds cannot be as-
cribed to mere coincidence. If the land had ever been
submerged during any part of the Glacial epoch to a depth
of 1,400 feet, it is inconceivable that clear and indisputable
evidence should not be found in abundance in the shel-
tered valleys of the Lake District and Wales, which would
have been deep, quiet fiords, in which vast colonies of ma-
rine creatures would have found harbour, as they do in the
deep lochs of Scotland to-day.

“Tt has been urged, in explanation of this risemce of
marine remains in the great hill-centres, that the ‘ second
glaciation’ might have destroyed them; but to do this
would require that the ice should make a clean and com-
plete sweep of all the loose deposits both in the hollows of
the valleys and on the hill-sides, and further that it should
destroy all the shells and all the foreign stones which
floated in during the submergence. At the same time we
should have to suppose that the drift which lay in the
paths of the great glaciers was not subjected to any inter-
ference whatever. But, assuming that these difficulties
were explained, there would still remain the fact that the
valleys which have never been glaciated—as, for example,
those of Derbyshire—show no signs whatever of any ma-
rine deposits, nor of marine action in any form whatever.

“he sea leaves other traces also, besides shells, of its
presence in districts that have really been submerged, yet
there are no signs whatever to be found of them in all Eng-
land, except the post-glacial raised beaches. Furthermore,
in all the area occupied by glacial deposits there are no true
sea-beaches, no cliffs nor sea-worn caves, no barnacle-
encrusted rocks, nor rocks bored by Pholas or Saxicava.
Are we to believe that these never existed ; or that, having
existed, they have been obliterated by subsequent denuda-
tions? To make good the former proposition, it would be

4

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 175

necessary as a preliminary to show that the movement of
subsidence and re-elevation was so rapid, and the interval
between so brief, that no time was allowed for any marine
erosion to take place. If this were so, it would be the most
stupendous catastrophe of which we have any geological
record; but we are not left in doubt regarding the duration
of the submerged condition, for the occurrence of forty feet
of gravel upon the summits of the hills indicates plainly
that, if they were accumulated by the sea, the land must
have stood at that level for a very long period, amply suffi-
cient for the formation of a well-marked coast-line.

“The alternative proposition, that post-glacial denuda-
tion had removed the traces of subsidence, is equally at
variance with the evidence. Post-glacial denudation has
left kames and drumlins, and all the other forms of glacial
deposits, in almost perfect integrity ; the small kettle-holes
are not yet filled up; and it is therefore quite out of the
question that the far more enduring features, such as sea-
cliffs, shore platforms, and beaches, should have been de-
stroved.

“ The only reasonable conclusion is, that these evidences
of marine action never existed, because the land in glacial
times was never depressed below its present level. If the
level were different at all (as I think may have been the
case on the western side of England), it was higher, and
not lower.

“'The details of the submergence hypothesis have, so far
as I am aware, never been dealt with by its advocates, oth-
erwise I cannot but think that it would have been aban-
doned long since. It has been stated in general terms that
the subsidence was greatest in the north and diminished
to zero in the south, but no attempt was made to trace the
evidence of extreme subsidence across country and along
the principal hill-ranges—in fact, to see how it varied in
every direction.

“Tf we take a traverse of England, say from Flam-

1622
iv

MAN AND THE GLACIAL PERIOD.

176

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ANCIENT GLACIERS IN EASTERN HEMISPHERE. 177

which it again protrudes
on the western side of
the valley of the Ouse,
and however the drift
_ between there and the
Pennine’ water - shed
may be interpreted, it
shows not a sign of ma-
rine origin; but, even
granting that it did, we
find that it does not
reach within a thousand
feet of the water-shed.
When the water-shed is
crossed, however, abun-
dant glacial deposits are
met with which are not
to be differentiated from

2 contorted and nearly

greenish-yellow sand with many

Scale, 4 feet to 1 inch,

streaks, of

and brown clay of aqueous origin, beddin

ar seam, and seattered

ac. Patch of pale-yellow sand, different from 20, without trace of fossils,

others at slightly lower
levels which contain
shells.

“Tf we suppose that
the line of our traverse
crosses the Pennine
Chain at Heald Moor,
we shall find that on
the eastern side no
traces of drift occur
above about 300 feet;
while the very summit
of the water-shed is oc-
cupied by boulder-clay,
and thence downward
the trace is practically
continuous, and at about
1,000 feet and down-

db. Irregul

Pure compact blue
2

2a.

obliterated, but the mass is cut up by shearing: planes.

marine shells.

Fra. 48 —Enlarged section of the shelly sand and surrounding clay at B in preceding figure.

ExXPpLANATION.—%. ‘‘ Basement”? boulder-clay.

ii.

178 MAN AND THE GLACIAL PERIOD.

ward the drift contains marine shells. Across the great
plain of Lancashire and Cheshire the ‘marine’ drift is
fully developed—though it may be remarked in parenthe-
ses that it contains a shallow-water fauna, albeit ex hy-
pothesi deposited, in part at least, in a depth of 200 fath-
oms of water—and to the Welsh border at Frondeg, where
it again reaches a water-shed at an altitude of 1,450 feet ;
but at 100 yards to the westward of the summit all traces
of subsidence disappear, and through the centre of Wales
no sign is visible; then we emerge on the western slopes
at Moel Tryfaen, and they assume their fullest dimensions,
though only to finish abruptly on the hill-top, and put in
no appearance in the lower grounds which extend from
there to the sea.

“The conclusions pointed to by the evidence (and, as I
have endeavoured to show, all the evidence which existed
at the close of the Glacial period is there still) are, that
a subsidence of the Yorkshire Wolds took place on the
east, but not in the centre or west; that the Pennine Chain
was submerged on the western side to a depth of 1,400
feet, and on the east to not more than 300 feet, even on op-
posite sides of the same individual hill; that all the low-
jands between, say, Bacup and the Welsh border, were sub-
merged, and that the hills near Frondeg partook of this
movement, but only on their eastern sides ; that the cen-
tre of Wales was exempt, but that the summit of Moel
Tryfaen forms an isolated spot submerged, while the sur-
rounding country escaped. These absurdities might be
indefinitely multiplied, and they must follow unless it be
admitted that the phenomenaare the results of glacial ice,
and that ice ean move ‘ up-hill.’

“The south of England certainly has partaken of no
movement of subsidence. A line drawn from Bristol to
London will leave all the true glacial deposits to the north-
ward, except a bed of very questionable boulder-clay at
Watchet, and a peculiar deposit of clayey rubble which

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 179

has been produced on the flanks of the Cornish hills prob-
ably, as the late 8. V. Wood, Jr, suggested, by the slip-
ping of material over a permanently frozen subsoil.

‘“‘ For the remainder of the southern area the evidence is
plain that there has been no considerable subsidence dur-
ing glacial times. ‘The presence over large areas of chalk
country of the ‘clay with flints "—a deposit produced by
the gradual solution of the chalk and the accumulation
in situ of its insoluble residue—is absolute demonstration
that for immense periods of time the country has been ex-
empt from any considerable aqueous action. The enor-
mous accumulations of china clay upon the granite bosses
of Cornwall and Devon tell the same tale. A few erratics
have been found at low levels at various points on the
southern coasts, usually not above the reach of the waves.
These consist of rocks which may have been floated by
shore-ice from the Channel Islands or the French coast.
«This imperfect survey of the evidence against the sup-
posed submergence has been rendered the more difficult by
the fact that it is not considered necessary to produce the
evidence of marine shells in all cases. Indeed, it has been
argued that post-Tertiary beds covering thousands of square
miles might be absolutely destitute of shells without preju-
dice to the theory of their formation in the sea.

“ But such a suggestion, one would think, could hardly
come from any one familiar with marine Tertiary deposits,
or even with the appearance of modern sea-beaches. Ad-
mitting, however, for the purposes of argument, that the
beaches along a great extent of coast might be devoid of
shells, it cannot be argued that the deep waters were desti-
tute of life ; and hence the boulder-clays, if of marine origin,
should contain a great abundance of shells and other re-
mains, and, once entombed, it is beyond belief that they
could all be removed from such a deposit in the short lapse
of post-glacial time.

“‘ Now, some of the boulder-clays—as, for example, those

180 MAN AND THE GLACIAL PERIOD.

of Lancashire and Cheshire—are held to be of marine ori-
gin, and this is indeed a vital necessity to the submergence
theory ; for, if these are not marine deposits, neither are the
other shelly deposits; but these boulder-clays are abso-
lutely indistinguishable from those lying within the hill-
centres, and, as it passes belief that such deposits could be
of diverse origin and yet possess an identical structure and
arrangement, then we should have a right to demand that
these clays should have enclosed shells and should still con-
tain them, but they do not.

- “T may here mention that Iam informed by Mr. W.
Shone, F. G.5.—and he was good enough to permit me to
quote the statement—that the boulder-clay of Cheshire and
the shelly boulder-clay of Caithness are ‘as like as two
peas.’ The importance of this comparison les in the fact
_ that, since Croll’s classical description, all observers have
agreed that it was the produet of land-ice which moved in
upon the land out of the Dornoch Firth. It was pointed
out then, as since has been done for England, that it was
only where the direction of ice-movement was from the
seaward that any shells occur in the boulder-clay.

“The Dispersion of Erraties of Shap Granite-—So
great a significance attaches to the peculiar distribution
of this remarkable rock, that I may add a few details here
which could not be conveniently introduced elsewhere.

“This granite occupies an area which lies just to the
northward of the water-shed between the basins of the
Lime and the Eden, and its extreme elevation is 1,656 feet.
Boulders occur in large numbers as far to the northward
as Cross Fells, while, as already described, they pass over
Stainmoor and are dispersed in great numbers along the
route taken by the great Stainmoor branch of the Sol-
way Glacier. But a considerable number of the boulders
also found their way to the southward, and a well-marked
trail can be followed down into Morecambe Bay; and at
Hest Bank, to the north of Lancaster, the boulder-clay

ANCIENT GLACIERS IN EASTERN HEMISPHERE. [81

contains many examples, together with the ‘ mica-trap ’
of the Kendal and Sedbergh dykes and other local rocks,
but no shells or erratics from other sources than the
country draining into Morecambe Bay. ‘lo the south-
ward the ice which bore these rocks was deflected by the
great Irish Sea Glacier, and, so far as present information
enables me to state, the Shap granite blocks mark the
course of the medial moraine between these two ice-streams.
It has been found near Garstang, at Longridge, and at
Whalley, this being the exact line of junction of the Irish
Sea Glacier with the ice from Morecambe Bay and the
Pennine Chain.

“Tt is a very remarkable and significant fact, that not
a single authentic occurrence of the rock across the bound-
ary indicated has yet been recorded.” .

Northern Hurope.

On passing over the shallow German Sea from England
to the Continent, the southern border of the Scandina-
vian ice-field is found south of the Zuyder Zee, between
Utrecht and Arnhem—the moraine hills in the vicinity of
Arnhem being quite marked, and a barren, sandy plain
dotted with boulders and irregular moraine hills extending
most of the way to the Zuyder Zee. From Arnhem the
southern boundary of the great ice-field runs “ eastward
across the Rhine Valley, along the base of the Westphalian
Hills, around the projecting promontory of the Hartz, and
then southward through Saxony to the roots of the Erzge-
birge. Passing next southeastward along the flanks of the
Riesen and Sudeten chain, it sweeps across Poland into
Russia, circling round by Kiev, and northward by Nijni-
Novgorod towards the Urals.’* Thence the boundary
passes northward to the Arctic Ocean, a little east of the
White Sea.

* A. Geikie’s Text-Book of Geology, p. 885.

189 MAN AND THE GLACIAL PERIOD.

The depth of this northern ice-sheet is proved to have
been upwards of 1,400 feet where it met the Hartz Moun-
tains, for it has deposited northern dédris upon them to
that height; while, as already shown, it must have been
over 2,000 feet in the main valley of Switzerland. In
Norway it is estimated that the ice was between 6,000
and 7,000 feet thick.

The amount of work done by the continental glaciers
of Europe in the erosion, transportation, and deposition of
rock and earthy material is immense. According to Hell-
and, the average depth of the glacial deposits over North
Germany and northwestern Russia is 150 German feet,
1. e., about 135 English feet. As the deposition towards
the margin of a glacier must be commensurate with its
erosion near the centre of movement, this vast amount
imphes a still greater proportionate waste in the moun-
tains of Scandinavia, where the area diminishes with every
contraction of the circle. Two hundred and fifty feet is
therefore not an extravagant calculation for the amount
of glacial erosion in the Scandinavian Peninsula.

It is not difficult to see how the Scandinavian moun-
tains were able to contribute so much soil to the plains of
northern Germany and northwestern Russia. Previous to
the Glacial period, a warm climate extended so far north as
to permit the growth of semi-tropical vegetation in Spitz-
bergen, Greenland, and the northern shores of British
America. Such a climate, with its abundant moisture
and vegetation, afforded most favourable conditions for the
superficial disintegration of the rocks. When, therefore,
the cold of the Glacial period came orf, the moving cur-
rents of ice would have a comparatively easy task in strip-
ping the mantle of soil from the hills of Norway and
Sweden, and transporting it towards the periphery of its
movement. Of course, erosion in Scandinavia meant
subglacial deposition beyond the Baltic. Doubtless, there-
fore, the plains of northern Germany, with their great

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 183

depth of soil, are true glacial deposits, whose inequalities
of surface have since been much obliterated, through the
general influences of the lapse of time, and by the ceaseless
activity of man.

An interesting series of moraines in the north of Ger-
many, bordering the Baltic Sea, was discovered in 1888 by
Professor Salisbury, of the United States Geological Sur-
vey. Its course hes through Schleswig-Holstein, Meck-
lenburg, Potsdam (about forty miles north of Berlin),
thence swinging more to the north, and following nearly
the line between Pomerania and West Prussia, crossing
the Vistula about twenty miles south of Dantzic, thence
easterly to the Spirding See, near the boundary of Po-
land.

Among the places where this moraine can be best seen
are—‘1. In Province Holstein, the region about (espe-
cially north of) Eutin; 2. Province Mecklenburg, north of
Crivitz, and between Biitow and Krépelin; 3. Province
Brandenburg, south of Reckatel, between Strassen and
Barenbusch, south of Fiirstenberg and north of Evers-
walde, and between Pyritz and Solden; 4. Province Posen,
east of Locknitz, and at numerous points to the south, and
especially about Falkenburg, and between Lompelburg and
Barwalde. ‘This is one of the best localities. 5. Province
West Preussen, east of Biitow; 6. Province Ost Preussen,
between Horn and Widikin.”

Comparing these with the moraines of America, Pro-
fessor Salisbury remarks:

“Tn its composition from several members, in its variety
of development, in its topographic relations, in its topog-
raphy, in its constitution, in its associated deposits, and
in its wide separation from the outermost drift limit, this
morainic belt corresponds to the extensive morainic belt
of America, which extends from Dakota to the Atlantic
Ocean. ‘That the one formation corresponds to the other
does not admit of doubt. In all essential characteristics

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the moraines in Britain and Germany according to Lewi

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 185

they are identical in character. What may be their rela-
tions in time remains to be determined.”

The physical geography of Europe is so different from
that of America, that there was a marked difference in
the secondary or incidental effects of the Glacial period
upon the two regions. In America the continental area
over which the glaciers spread is comparatively simple in
its outlines. ast of the Rocky Mountains, as we haye
seen, the drainage of the Glacial period was, for a time,
nearly all concentrated in the Mississippi basin, and the
streams had a free course southward.

But in Europe there was no free drainage to the south,
except over a small portion of the glaciated area in central
Russia, about the head-waters of the Dnieper, the Don,
and the Volga; though the Danube and the Rhone af-
forded free course for the waters of a portion of the great
Alpine glaciers. But all the great rivers of northern
Kurope flow to the northward, and, with the exception of
the Seine, they all for a time encountered the front of the
continental ice-sheet. This circumstance makes it dif-
ficult to distinguish closely between the direct glacial
deposits in Europe and those which are more or less
modified by water action. At first sight it would seem
also somewhat hazardous to attempt to correlate with any
portion of the Glacial period the deposition of the gravelly
and loamy deposits in valleys, which, like those of the
Seine and Somme, lie entirely outside of the glaciated
area. 3

Upon close examination, however, the elements of
doubt more and more disappear. ‘The Glacial period was
one of great precipitation, and it is natural to suppose
that the area of excessive snow-fall extended considerably
beyond the limit of the ice-front. During that period,
therefore, the rivers of central France must have been an-
nually flooded to an extent far beyond anything which is
known at the present time. Since these rivers flowed to

186 MAN AND THE GLACIAL PERIOD.

the northward, at a period when, during the long and
severe winters, the annual accumulation of ice near their
mouths was excessive, ice-gorges of immense extent, such
as now form about the mouths of the Siberian rivers,
would regularly occur. We are not surprised, therefore,
to find, even in these streams, abundant indications of the
indirect influence of the great northern ice-sheet.

The indications referred to consist of high-level gravel
terraces occasionally containing boulders, of from four to
five tons weight, which have been transported for a con-

siderable distance. The elevation of the terraces above

the present flood-plains of the Seine and Somme reaches
from 100 to 150 feet. Weare not to suppose, however,
that even in glacial times the floods of the river Seine
could have filled its present valley to that height. ‘The
highest flood in this river known in historic times rose
only to a height of twenty-nine feet. Mr. Prestwich esti-
mates that, without taking into consideration the more
rapid discharge, a flood of sixty times this magnitude
would be required to fill the present valley to the level of
the ancient gravels, while at Amiens the shape of the val-
ley of the Somme is such that five hundred times the
mean average of the stream would be required to reach
the high-level gravels. The conclusion, therefore, is*that
the troughs of these streams have been largely formed by
erosion since the deposition of the high-level gravels.

Connected with these terrace gravels in northern
France is a loamy deposit, corresponding to the loess in
other parts of Europe, and to a similar deposit to which
we have referred in describing the southwestern part of
the glaciated area in North America. In northern France
this fine silt overlies the high-level gravel deposits, and,
as Mr. Prestwich has pretty clearly shown, was deposited
contemporaneously with them during the early inunda-
tions and before the stream had eroded its channel to its
present level.

a
ates

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 187

The distribution of loess in Europe was doubtless con-
nected with the peculiar glacial conditions of the con-
tinent. Its typical development is in the valley of the
Rhine, where it is described by Professor James Geikie
“as a yellow or pale greyish-brown, fine-grained, and
more or less homogeneous, consistent, non-plastic loam,
consisting of an intimate admixture of clay and carbonate
of lime. Itis frequently minutely perforated by long, ver-
tical, root-like tubes which are lined with carbonate of
lime—a structure which imparts to the loess a strong
tendency to cleave or divide in vertical planes. Thus it
usually presents upright bluffs or cliffs upon the margins
of streams and rivers which intersect it. Very often it
contains concretions or nodules of irregular form. .
Land-shells and the remains of land animals are the most
common fossils of the loess, but occasionally fresh-water
shells and the bones of fresh-water fish occur.”

“From the margins of the modern alluvial flats which
form the bottoms of the valleys it rises to a height of 200
or 300 feet above the streams—sweeping up the slopes of
the valleys, and imparting a rich productiveness to many
districts which would otherwise be comparatively unfruit-
ful. From the Rhienthal itself it extends into all the
tributary valleys—those of the Neckar, the Main, the
Lahn, the Moselle, and the Meuse, being more or less
abundantly charged with it. It spreads, in short, like a
great winding-sheet over the country—lying thickly in
the valleys and dying off upon the higher slopes and
plateaux. Wide and deep accumulations appear likewise
in the Rhone Valley, as also in several other river-valleys
of France, as in those of the Seine, the Sadne, and the Ga-
ronne, and the same is the case with many of the valleys
of middle Germany, such as those of the Fulda, the Werra,
the Weser, and the upper reaches of the great basin of
the Elbe. It must not be supposed that the loess is restricted
to valleys and depressions in the surface of the ground.

188 MAN AND THE GLACIAL PERIOD.

“Tt is true that it attains in these its greatest thick-
ness, but extensive accumulations may often be followed
far into the imtermediate hilly districts and over the
neighbouring plateaux. ‘Thus the Odenwald, the Taunus,
the Vogelgebirge, and other upland tracts, are cloaked
with loess up to a considerable height. Crossing into the
drainage system of the Danube, we find that this large
river and many of its tributaries flow through vast tracts
of loess. Lower Bavaria is thickly coated with it, and it
attains a great development in Bohemia, Upper and Lower
Austria, and Moravia—in the latter country rising to an ©
elevation of 1,300 feet. It is equally abundant in Hun-
gary, Galicia, Bukowina, and Transylvania. From the
Danubian flat lands and the low grounds of Galicia it
stretches into the valleys of the Carpathians, up to
heights of 800 and 2,000 feet. In some cases it goes
even higher—namely, to 3,000 feet, according to Zeusch-
ner, and to 4,000 or 5,000 feet, according to Korzistka.
These last great elevations, it will be understood, are
in the upper valleys of the northern Carpathians. | In
Roumania loess is likewise plentiful, but it has not been
observed south of the Balkans. East of the Carpa-
thians—that is to say, in the regions watered by the
Dniester, the Dnieper, and the Don—loess appears also
to be wanting, and to be represented by those great
steppe-deposits which are known as T7chernozen, or black
earth.” *

The shells found in the loess indicate both a colder and
a wetter climate during its deposition than that which now
exists. The relics of land animals are infrequently found
in the deposit, yet they do occur, but mostly in fragment-
ary condition—the principal animals represented being
the mammoth, the rhinoceros, the reindeer, and the horse ;
which is about the same variety as is found in the gravel

* Prehistoric Europe, pp. 144-146.

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 189

deposits of the Glacial period, both in western Europe and
in America.

A species of loess—differing, however, somewhat in
color from that on the Rhine—covers the plains of north-
eastern France up to an elevation of 700 feet above the
the sea, where, as we have already said, it overlies the high-
level gravels of the Seine and the Somme. Above this
height the superficial soil in France is evidently merely
the decomposed upper surface of the native rock.

The probable explanation of all these deposits, included
under the term “ loess,” is the same as that already given
by Prestwich of the loamy deposits of northern France.
But in case of rivers, which, like the Rhine, encountered
the ice-front in their northward flow, a flooded condition
favouring the accumulation of loess was doubtless promoted
by the continental ice-barrier. In the case of the Danube
and the Rhéne, however, where there was a free outlet
away from the glaciated region, the loess in the upper part
of the valleys must have accumulated in connection with
glacial floods quite similar to those which we have de-
scribed as spreading over the imperfectly formed water-
courses of the Mississippi basin during the close of the Ice
age. That the typical loess is of glacial origin is pretty
certainly shown, both by its distribution mm front of gla-
ciers and by its evident mechanical origin when studied
under the microscope. It is, in short, the fine sediment
which gives the milky whiteness to glacial rivers.

In central Russia there is a considerable area in which
the glacial conditions were, in one respect, similar to those
in thenorthern part of the Mississippi Valley in the United
States. In both regions the continental ice-sheet sur-
mounted the river partings, and spread over the upper
portion of an extensive plain whose drainage was to the
south. The Dnieper, the Don, and the western branch of
the Volga, like the Ohio and the Mississippi, have their
head-waters in the glaciated region. In some other respects,

“eee

also, there is a resemblance between the plaifys bordering
the glaciated region in central Russia and those which in
America border it in the Mississippi Valley. Mr. James
Geikie is of the opinion that the extensive belt of black
earth adjoining the glaciated areain Russia, and constitut-
ing the most productive agricultural portion of the country,
derives its fertility, as does much of the Mississippi Valley,
from the blanket of glacial silt spread pretty evenly over it.
Thus it would appear that in Europe, as in America, the
ice of the Glacial period was a most beneficent agent, pre-
paring the face of the earth for the permanent occupation
of man. On both continents the seat of empire is in the
area once occupied by the advance of the great 1ce-move-
ments of that desolate epoch.

190 MAN AND THE GLACIAL PERIOD.

Asia.

East of the Urals, in northern Asia, there is no evidence
of moving ice upon the land during the Glacial period ;
but at Yakutsk, in latitude 62° north, the soil is frozen at
the present time to an unknown depth, and many of the
Siberian rivers, as they approach and empty into the Arctic
Sea, flow between cliffs of perpetual ice or frozen ground.
The changes that came over this region during the Glacial
period are impressively indicated by the animal remains
which have been preserved in these motionless icy cliffs.
In the early part of the period herds of mammoth and
woolly rhinoceros roamed over the plains of Siberia, and
waged an unequal warfare with the slowly converging and
destructive forces. ‘The heads and tusks of these animals
were so abundant in Siberia that they long supplied all
Russia with ivory, besides contributing no small amount
for export to other countries. “In 1872 and 1873 as
many as 2,770 mammoth-tusks, weighing from 140 to 160
pounds each, were entered at the London docks.”* So

* Prestwich’s Geology, vol. 11, p. 460.

ANCIENT GLACIERS IN EASTERN HEMISPHERE. 19]

perfectly have the carcasses of these extinct animals been
preserved in the frozen soil of northern Siberia that when,
after the lapse of thousands of years, floods have washed
them out from the frozen cliffs, dogs and wolves and bears
have fed upon their flesh with avidity. In some instances
even “portions of the food of these animals were found in
the cavities of the teeth. Microscopic examination showed
that they fed upon the leaves and shoots of the coniferous
trees which then clothed the plains of Siberia.” A skele-
ton and parts of the skin, and some of the softer portions
of the body of a mammoth, discovered in 1799 in the
frozen cliff near the mouth of the Lena, was carried to
St. Petersburg in 1806, from which it was ascertained that
this huge animal was “ covered with a light-coloured, curly,
very thick-set hair one to two inches in length, inter-
spersed with darker-colored hair and bristles from four to
eighteen inches long.” *

In the valleys of Sikkim and eastern Nepaul, in
northern India, glaciers formerly extended 6,000 feet
lower than now, or to about the 5,000-foot level, and in
the western Himalayas to a still lower level. The higher
ranges of mountains in other portions of Asia also show
many signs of former glaciation. This is specially true
of the Caucasus, where the ancient glaciers were of vast
extent. According, also, to Sir Joseph Hooker, the cedars
of Lebanon flourish upon an ancient moraine. Of the
glacial phenomena in other portions of Asia little is known.

Africa.
Northern and even central Africa must likewise come
in for their share of attention. The Atlas Mountains, ris-
ing toa height of 13,000 feet, though supporting none at

the present time, formerly sustained glaciers of consider-
able size. Moraines are found in several places as low as

14 * Prestwich’s Geology, vol. ii, p. 460.

192 MAN AND THE GLACIAL PERIOD.

the 4,000-foot level, and one at an altitude of 4,000 feet
is from 800 to 900 feet high, and completely crosses
and dams up the ravine down which the glacier formerly
came.

Some have supposed that there are indubitable eyi-
dences of former glaciation in the mountain-ranges of
southwestern Africa between latitude 30° and 33°, but
the evidence is not as unequivocal as we could wish, and
we will not pause upon it.

The mountains of Australia, also, some of which rise
to a height of more than 7,000 feet, are supposed to have
been once covered with glacial ice down to the level of
5,800 feet, but the evidence is at present too scanty to
build upon. But in New Zealand the glaciers now clus-
tering about the peaks in the middle of the South Island,
culminating in Mount Cook, are but diminutive repre-
sentatives of their predecessors. ‘This is indicated by ex-
tensive moraines in the lower part of the valleys and by
the existence of numerous lakes, attributable, like so many
in Europe and North America, to the irregular deposi-
tion of morainic material by the ancient ice-sheet.*

* See With Axe and Rope in the New Zealand Alps, by G. E.
Mannering, 1891.

Cheba eibidle, AV IOL,
DRAINAGE SYSTEMS AND THE GLACIAL PERIOD.

We will begin the consideration of this part of our
subject, also, with the presentation of the salient facts in
North America, since that field is simpler than any field
in the Old World.

The natural drainage basins of North America east of
the Rocky Mountains are readily described. The Missis-
sipp1 River and its branches drain nearly all the region
lying between the Appalachian chain and the Rocky
Mountains and south of the Dominion of Canada and of
the Great Lakes. All the southern tributaries to the Great
Lakes are insignificant, the river partings on the south
being reached in a very short distance. The drainage of
the rather limited basin of the Great Lakes is northeast-
ward through the St. Lawrence River, leaving nearly all
of the Dominion of Canada east of the Rocky Mountains
to pour its surplus waters northward into Hudson Bay
and the Arctic Ocean. With the exception of the St.
Lawrence River, these are essentially permanent systems
of drainage. ‘lo understand the extent to which the ice
of the Glacial period modified these systems, we must first
get before our minds a picture of the country before the
accumulation of ice began.

Preglacial Erosion.

Reference has already been made to the elevated con-
dition of the northern and central parts of North Amer-'

194 MAN AND THE GLACIAL PERIOD.

ica at the beginning of the Glacial period. The direct
proof of this preglacial elevation is largely derived from
the fiords and great lake basins of the continent. The
word “ fiord ’”’ is descriptive of the deep and narrow inlets
of the sea specially characteristic of the coasts of Norway,
Denmark, Iceland, and British Columbia. Usually also
fiords are connected with valleys extending still farther
inland, and occupied by streams.

Fiords are probably due in great part to river erosion
when the shores stood at considerably higher level than |
now. Slowly, during the course of ages, the streams wore
out for themselves immense gorges, and were assisted, per-
haps, to some extent by the glaciers which naturally
came into existence during the higher continental eleva-
tion. ‘The present condition of fiords, occupied as they
usually are by great depths of sea-water, would be ac-
counted for by recent subsidence of the land. In short,
fiords seem essentially to be submerged river gorges, par-
tially silted up near their mouths, or ee partially
closed by terminal moraines.

It is not alone in northwestern Europe and British
Columbia that fiords are found, but they characterize as
well the eastern coast of America north of Maine, while
even farther south, both on the Atlantic and on the Pa-
cific coast, some extensive examples exist, whose course
has been revealed only to the sounding-line of the Gov-
ernment survey.

The most remarkable of the submerged fiords in the
middle Atlantic region of the United States is the con-
tinuation of the trough of Hudson River beyond New
York Bay. As long ago as 1844 the work of the United
States Coast Survey showed that there was a submarine
continuation of this valley, extending through the com-
paratively shallow waters eighty miles or more seaward
from Sandy Hook.

The more accurate surveys conducted from 1880 to

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 195

1884 have brought to our knowledge the facts about this
submarine valley almost as clearly as those relating to the

d

> WIHd Way

Ysa Bou,
yy]
Mois, i

7 ss Z yy 3s Wy

WK 2
ay 4/,N E2ZW JE

=|
co
z

Fic. 50.—Map showing old channel and mouth of the Hudson (Newberry).
inland portion of it above New York city. According to
Mr. A. Lindenkohl,* this submarine valley began to be
noticeable in the soundings ten miles southeast of Sandy
Hook. The depth of the water where the channel begins
is nineteen fathoms (114 feet). Ten miles out the chan-

* Bulletin of the Geological Society of America, vol. i, p. 564;
American Journal of Science, June, 1891.

196 MAN AND THE GLACIAL PERIOD.

nel has sunk ninety feet below the general depth of the
water on the bank, and continues at this depth for twenty
miles farther. ‘This narrow channel continues with more
or less variation for a distance of seventy-five miles, where
it suddenly enlarges to a width of three miles and to a
depth of 200 fathoms, or 1,200 feet, and extends for a dis-
tance of twenty-five miles, reaching near that point a
depth of 474 fathoms, or 2,844 feet. According to Mr.
Lindenkohl, this ravine maintains for half its length “a
vertical depth of more than 2,000 feet, measuring from
the top of its banks, and the banks have a nearly uni-
form slope of about 14°. The mouth of the ravine opens
out into the deep basin of the central Atlantic. Z

With little question there is brought to light in these
remarkable investigations a channel eroded by the exten-
sion of the Hudson River, into the bordering shelf of the
Atlantic basin at a time when the elevation of the conti-
nent was much greater than now. This is shown to have
occurred in late Tertiary or post-Tertiary times by the
fact that the strata through which it is worn are the con-
tinuation of the Tertiary deposits of New Jersey. The
subsidence to its present level has probably been gradual,
and, according to Professor Cook, is still continuing at
the rate of two feet a century.

Similar submarine channels are found extending out
from the present shore-line to the margin of the narrow
shelf bordering the deep water of the central Atlantic
running from the mouth of the St. Lawrence River,
through St. Lawrence Bay, and through Delaware and
Chesapeake Bays.* All these submerged fiords on the
Atlantic coast were probably formed during a continental
elevation which commenced late in the Tertiary period,
and reached the amount of from 2,000 to 3,000 feet in
the northern part of the continent.

=—_> >

* See Lindenkohl in American Journal of Science, for June, 1891.

4

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 197

To this period must probably be referred also the
formation of the gorge, or more properly fiord, of the

| Me Va

a)

Hl

Island (Newberry).

ia, 51.—New York harbor in preglacial times, looking south, from south end of New York

& ‘:

ral NWS
ae
nae

Saguenay, which joins the St. Lawrence below Quebec.
The great depth of this fiord is certainly surprising, since,
according to Sir William Dawson, its bottom, for fifty
miles above the St. Lawrence, is 840 feet below the sea-
level, while the bordering cliffs are in some places 1,500
feet above the water. The average width is something
over a mile.

198 MAN AND THE GLACIAL PERIOD.

It seems impossible to account for such a deep gorge
extending so far below the sea-level, except upon the sup-
position of a long-continued continental elevation, which
should allow the stream to form a cafion to an extent
somewhat comparable with that of the cafions of the
Colorado and other riversin the far West. Then, upon
the subsidence of the continent to the present level, it
would remain partially or wholly submerged, as we find it
at the present time. During the Glacial period it was so
filled with ice as to prevent silting up. The rivers enter-
ing the Pacific Ocean, beth in the United States and in
British Columbia, are also lost in submerged channels ex-
tending out to the deeper waters of the Pacific basin in a
manner closely similar to the Atlantic streams which have
been mentioned.

During this continental elevation which preceded,
accompanied, and perhaps brought on the Glacial period,
erosion must have proceeded with great intensity along
all the lines of drainage, and throughout the whole re-
gion which is now covered, and to a considerable extent
smoothed over, by glacial deposits, and the whole country
must have presented a very different appearance from
what it does now.

A pretty definite idea of its preglacial condition can
probably be formed by studying the appearance of the
regions outside of and adjoining that which was covered
by the continental glacier. The contrast between the
glaciated and the unglaciated region is striking in several
respects aside from the presence anl absence of trans-
ported rocks and other dédris, but in nothing is it greater

han in the extent of river erosion which is apparent upon
the surface. For example, upon the western flanks of the
Alleghanies the regions south of the glacial limit is every-
where deeply channeled by streams. Indeed, so long have
they evidently been permitted to work in their present
channels that, wherever there have been waterfalls, they

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 199

have receded to the very head-waters, and no cataracts
exist in them at the present time. Nor aré there in the
unglaciated region any lakes of importance, such as char-
acterize the glaciated region. If there have been lakes,
the lapse of time has been sufficient for their outlets to
lower their beds sufficiently to drain the basins dry.

On entering the glaciated area all this is changed.
The ice-movement has everywhere done much to wear
down the hills and fill the valleys, and, where there was
debris enough at command, it has obliterated the narrow
gorges originally occupied by the preglacial streams.
Thus it has completely changed the minor lines of super-
ficial drainage, and in many instances has produced most
extensive and radical changes in the whole drainage sys-
tem of the region. In the glaciated area, channels buried
beneath glaciated débris are of frequent occurrence, while
many of the streams which occupy their preglacial chan-
nels are flowing at a very much higher level than formerly,
the lower part of the channel having been silted up by the
superabundant débris accessible since the glacial move-
ment began.

Buried Outlets and Channels.

It is easy to see how the great number of shallow lakes
which frequent the glaciated region were formed by the
irregular deposition of glacial débris, but it is somewhat
more difficult to trace out the connection between the
Glacial period and the Great Lakes of North America,
several of which are of such depth that their bottoms are
some hundreds of feet below the sea-level, Lake Erie
furnishing the only exception. This lake is so shallow
that it is easy to see how its basin may have been princi-
pally formed by river erosion, while it is evident that
such must have been the mode of its formation, since it is
surrounded by sedimentary strata lying nearly in a hori-
zontal position.

200 MAN AND THE GLACIAL PERIOD.

That Lake Erie is really nothing but a “ glacial mill-
pond” is proved also by much direct evidence, especially
that derived from the depth of the buried channels of the
streams flowing into it from the south. Of these, the
Cuyahoga River, which enters the lake at Cleveland, has
been most fully investigated. In searching for oil, some
years ago, borings were made at many places for twenty-
five miles above the mouth of the river. Asa result, it
appeared that for the whole distance the rocky bottom of
the gorge was about two hundred feet below the present
bottom of the river, while the river itself is two or three
hundred feet below the general level of the country, occu-
pying a trough about half a mile in width, with steep,
rocky sides. These facts indicate that at one time the

Boston Ledace

eS e Gagahoge
= ; Drift depostts = Sate
Le waaeae Saujeen z oe t El Ff Berea. and sé.
= = SS Shale

Fic. 52.—Section across the valley of the Cuyahoga River, twenty miles above
its mouth (Claypole).

river must have found opportunity to discharge its con-
tents at a level two hundred feet below that of the present
lake, while an examination of the material filling up the
bottom of the gorge to its present level shows it to be
glacial dédris, thus proving that the silting up was accom-
plished during the Glacial period.

As the water of Lake Erie is for the most part less
than one hundred feet in depth, and is nowhere much
more than two hundred feet deep, it is clear that the pre-
glacial outlet which drained it down to the level of the
rocky bottom of the Cuyahoga River must have destroyed
the lake altogether. Hence we may be certain that, before
the Glacial period, the area now covered by the lake was

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 90]

simply a broad, shallow valley through which there coursed
a single river of great magnitude, with tributary branches
occupying deep gorges. Professor J. W. Spencer has
shown with great probability that the old line of drainage
from Lake Erie passed through the lower part of the val-
ley of Grand River, in Canada, and entered Lake Ontario
at its western extremity, and that during the great Ice
age this became so completely obstructed with glacial dé-
bris as to form an impenetrable dam, and to cause the
pent-up water to flow through the Niagara Valley, which
chanced to furnish the lowest opening.

In speaking of the present area of Lake Erie, however,
as being then occupied by a river valley, we do not mean
to imply that it was not afterwards greatly modified by
glacial erosion; for undoubtedly this was the case, what-
ever views we may have as to the relative efficiency of ice
and water in scooping out lake basins.

In the case of Lake Erie, we need suppose no change
of level to account for the erosion of its basin, but only
that, since the strata in which it is situated were deposited,
time enough had elapsed for a great river to cut a gorge
extending from the western end of Lake Ontario through
to the present bed of Lake Erie, and that here a great en-
largement of the valley was occasioned by the existence
of deep beds of soft shale which could easily be worn away
by a ramifying system of tributary streams. Rivers act-
ing at present relative levels would be amply sufficient to
preduce the results which are here manifest.

But in the case of Lakes Ontario, Huron, Michigan,
and Superior, whose depths descend considerably below
the sea-level, we must suppose that they were, in the
main, eroded when the continent was so much elevated
that their bottoms were brought above tide-level. The
depth of Lake Ontario implies the existence of an outlet
more than four hundred feet lower than at present,
which, of course, could exist only when the general ele-

209, MAN AND THE GLACIAL PERIOD.

vation was more than four hundred feet greater than
now.

The existence of an outlet at that depth seems to be
proved also by the fact that at Syracuse, where numerous
wells have been sunk to obtain brine for the manufacture
of salt, deposits of sand, gravel, and rolled stones, four hun-
dred and fifty feet thick, are penetrated without reaching
rock. Since this lies in the basin of Lake Ontario, it fol-
lows that if the basin itself has been produced by river
erosion, the land must have been of sufficient height to
permit an outlet through a valley, or cafion, of the required
depth, and this outlet must now be buried beneath the
abundant glacial dédris that covers the region.

Professor Newberry, who has studied the vicinity care-
fully, is of the opinion that there is ample opportunity
for such a line of drainage to have extended through the
Mohawk Valley to the Hudson River. But, at Little Falls,
a spur of the Adirondack Mountains projects into the
valley, and the Archzan rocks over which the river runs
are so prominent and continuous that some have thought it
impossible for the requisite channel to have ever existed
there. Extensive deposits of glacial débris, however, are
found in the vicinity, especially in places some distance to
the north, and in Professor Newberry’s opinion the exist-
ence of a buried channel around the obstruction pee the
north side is by no means improbable.

The preglacial drainage of Lake Huron has not been
determined with any great degree of probability. Pro-
fessor Spencer formerly supposed that it passed from the
southern end of the lake through London, in the western
part of Ontario, and reached the Erie basin near Port
Stanley, and so augmented the volume of the ancient
river which eroded the buried cafion from Lake Erie to
Lake Ontario. But he now supposes, though the evidence
is by no means demonstrative, that the waters of Lake
Huron passed into Lake Ontario by means of a channel

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 903

extending from Georgian Bay to the vicinity of To-
ronto.

With a fair degree of probability, the basin of Lake
Superior is supposed by Professor Newberry to have been
joined to that of Lake Michigan by some passage, now
buried, considerably to the west of the Strait of Mackinac,
and thence to have had an outlet southward from the
vicinity of Chicago directly into the Mississippi River.
Of this there is considerable evidence furnished by deeply
buried channels which have been penetrated by borings
in various places in Kankakee, Livingston, and McLean
Counties, Hlinois; but the whole area extending from
Lake Michigan to the Mississippi is so deeply covered
with glacial débris that the surface of the country gives
no satisfactory indication of the exact lines of preglacial
drainage.

Some of the most remarkable instances of ancient
river channels buried by the glacial deposits have been
brought to ight in southwestern Ohio, where there has
been great activity in boring for gas and oil. At St.
Paris, Champaign County, for example, in a locality where
the surface of the rock near by was known to be not far
below the general level, a boring was begun and continued
to a depth of more than five hundred feet without reach-
ing rock, or passing out of glacial débris.

Many years ago Professor Newberry collected suffi-
cient facts to show that pretty generally the ancient bed
of the Ohio River was as much as 150 feet below that
over which it now flows. During a continental elevation
the erosion had proceeded to that extent, and then the
channel had been silted up during the Glacial period with
the abundant material carried down by the streams from
the glaciated area. One of the evidences of the pregla-
cial depth of the channel of the Ohio was brought to
light at Cincinnati, where “gravel and sand have been
found to extend to a depth of over one hundred feet below

Psp

204 MAN AND THE GLACIAL PERIOD.

low-water mark, and the bottom of the trough has not
been reached.” In the valley of Mill Creek, also, “in the
suburbs of Cincinnati, gravel and sand were penetrated
to the depth of 120 feet below the stream before reaching
rock.” But from the general appearance of the channel,
Professor J. F'. James was led to surmise that a rock
bottom extended all the way across the present channel
of the Ohio, between Price Hill and Ludlow, Ky., a short
distance below Cincinnati, which would preclude the

possibility of a preglacial outlet at the depth disclosed in |

that direction. Mr. Charles J. Bates (who was inspector
of the masonry for the Cincinnati Southern Railroad while
building the bridge across the Ohio at this point) informs
me that Mr. James’s surmise is certainly correct, and that
his “in all probability ” may be displaced by “ certainly,”
since the bedded rocks supposed by Professor James to
extend across the river a few feet below its present bottom
were found by the engineers to be in actual existence.

In looking for an outlet for the waters of the upper
Ohio which should permit them to flow off at the low
level reached in the channel at Cincinnati, Professor
James was led to inspect the valley extending up Mill
Creek to the north towards Hamilton, where it joins the
Great Miami. The importance of Mill Creek Valley is
readily seen in the fact that the canal and the railroads
have been able to avoid heavy grades by following it. from
Cincinnati to Hamilton. Asa glance at a map will show,
it is also practically but a continuation of the northerly
course pursued by the Ohio for twenty miles before reach-
ing Cincinnati.- This, therefore, was a natural place in
which to look beneath the extensive glacial débris for the
buried channel of the ancient Ohio, and here in all prob-
ability it has been found. The borings which have been
made in Milk Creek Valley north of Cincinnati, show that
the bedded rock lies certainly thirty-four feet below the
low-water mark of the Ohio just below Cincinnati, while

t

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 205

at Hamilton, twenty-five miles north of Cincinnati, where
the valley of the Great Miami is reached, the bedded rock
of the valley lies as much as ninety feet below present
low-water mark in the Ohio.

Other indications of the greater depth of the pregla-
cial gorge of the Ohio are abundant. ‘“ At,the junction
of the Anderson with the Ohio, in Indiana, a well was
sunk ninety-four feet below the level of the Ohio before
rock was found.” At Louisville, Ky., the occurrence of
falls in the Ohio seemed at first to discredit the theory in
question, but Professor Newberry was able to show that
the falls at Louisville are produced by the water’s being
now compelled to flow over a rocky point projecting from
the north side into the old valley, while to the south there
is ample opportunity for an old channel to have passed
around this point underneath the city on the south side.
The lowlands upon which the city stands are made lands,
where glacial débris has filled up the old channel of the
Ohio.

Above Cincinnati the tributaries of the Ohio exhibit
the same phenomena. At New Philadelphia, Tuscarawas
County, the borings for salt-wells show that the Tuscara-
was is running 175 feet above its ancient bed. The
Beaver, at the junction of the Mahoning and Shenango,
is flowing 150 feet above the bottom of its old trough, as
is demonstrated by a large number of oil-wells bored in
the vicinity. Oil Creek is shown by the same proofs to
run from 7%) to 100 feet above its old channel, and that
channel had sometimes vertical and even overhanging
walls.*

The course of preglacial drainage in the upper basin
of the Alleghany River is worthy of more particular men-
tion. Mr. Carll, of the Pennsylvania Geological Survey,
has adduced plausible reasons for believing that previous

—_—<——

* Geological Survey of Ohio, vol. ii, pp. 18, 14.

906 MAN AND THE GLACIAL PERIOD.

to the Glacial period the drainage of the valley of the
upper Alleghany north of the neighbourhood of Tidioute,
in Warren County, instead of passing southward as now,
was collected into one great stream flowing northward
through the region of Cassadaga Lake to enter the Lake
Erie basin at Dunkirk, N. Y. ‘The evidence is that be-
tween Tidioute and Warren the present Alleghany is shal-
low, and flows over a rocky basin; but from Warren north-
ward along the valley of the Conewango, the bottom of
the old trough lies at a considerably lower level, and slopes
to the north. Borings show that in thirteen miles the
slope of the preglacial floor of Conewango Creek to the
north is 136 feet. The actual height above tide of the
old valley floor at Fentonville, where the Conewango
crosses the New York line, is only 964 feet; while that of
the ancient rocky fioor of the Alleghany at Great Bend,
a few miles south of Warren, was 1,170 feet. Again,
going nearer the head-waters of the Alleghany, in the
neighbourhood of Salamanca, it is found that the ancient
floor of the Alleghany is, at Carrollton, 70 feet lower than
the ancient bed of the present stream at Great Bend,
about sixty miles to the south; while at Cole’s Spring, in
the neighbourhood of Steamburg, Cattaraugus County,
N. Y., there has been an accumulation of 315 feet of drift
in a preglacial valley whose rocky floor is 155 feet below
the ancient rocky floor at Great Bend. Unless there has
been a great change in levels, there must, therefore, have
been some other outlet than the present for the waters
collecting in the drainage basin to the north of Great
Bend.* 3

While there are numerous superficial indications of
buried channels running towards Lake Erie in this region,

* For a criticism of Mr. Carll’s views, see an article on Pleisto-
cene Fluvial Planes of Western Pennsylvania, by Mr. Frank Ley-
erett, in American Journal of Science, vol. xlii, pp. 200-212.

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 907

direct exploration has not been made to confirm these
theoretical conclusions. In the opmion of Mr. Carll,
Chautauqua Lake did not flow directly to the north, but,
passing through a channel nearly coincident with that
now occupied by it, joined the northerly flowing stream
a few miles northeast from Jamestown.* It is probable,
however, that Chautauqua did not then exist as a lake,
since the length of preglacial time would have permitted
its outlet to wear a continuous channel of great depth cor-
responding to that known to have existed in the Cone-
wango and upper Alleghany.

The foregoing are but a few of the innumerable in-
stances where the local lines of drainage have been dis-
turbed, and even permanently changed, by the glacial de-
posits. Almost every lake in the glaciated region is a
witness to this disturbance of the established lines of
drainage by glacial action, while in numerous places where
lakes do not now exist they have been so recently drained
that their shore-lines are readily discernible.

An interesting instance of the recent disappearance of
one of these glacial lakes is that of Runaway Pond, in
northern Vermont. In the early part of the century the
Lamoille River had its source in a small lake in Crafts-
bury, Orleans County. The sources of the Missisquoi
River were upon the same level just te the north, and the
owner of a mill privilege upon this latter stream, desiring
to increase his power by obtaining access to the water of
the lake, began digging a ditch to turn it into the Mis-
sisquoi, but no sooner had he loosened the thin rim of
compact material which formed the bottom and the sides
of the inclosure, than the water began to rush out through
the underlying and adjacent quicksands. This almost in-
stantly enlarged the channel, and drained the whole body
of water off in an incredibly short time. Asa consequence,

—- $$

* Second Geological Survey of Pennsylvania, vol. iii.
15

208 MAN AND THE GLACIAL PERIOD.

the torrent went rushing down through the narrow val-
ley, sweeping everything before it; and nothing but the
unsettled condition of the country prevented a disaster
like that which occurred in 1889 at Johnstown, Pa.
Doubtless there are many other lakes held in position
by equally slender natural embankments. Artificial res-
ervoirs are by no means the only sources of such dan-
ger.
The buried channel of the old Mississippi River in
the vicinity of Minneapolis is another instructive example
of the instability of many of the present lines of drainage.
The gorge of the Mississippi River extending from Fort
Snelling to the Falls of St. Anthony at Minneapolis is of
post-glacial origin. One evidence of this is its narrow-
ness when contrasted with the breadth of the valley below
Fort Snelling. Below this point the main trough of the
Mississippi has a width of from two to eight miles, and
the faces of the bluffs on either side show the marks of
extreme age. ‘The tributary streams also have had time
to wear gorges proportionate to that of the main stream,
and the agencies which oxidise and discolor the rocks
have had time to produce their full effects. But from
Fort Snelling up to Minneapolis, a distance of about
seven miles, the gorge is scarcely a quarter of a mile in
width, and the faces of the high, steep bluffs on either side
are remarkably fresh looking by comparison with those
below; while the tributary gorges, of which that of the
Minnehaha River is a fair specimen, are very limited in
their extent.

Upon looking for the cause of this condition of things
we observe that the broad trough of the Mississippi River,
which had characterised it all the way below Fort Snel-
ling, continues westward, without interruption, up the val-
ley of the present Minnesota River, and, what seems at
first most singular, it does not cease at the sources of the
Minnesota, but, through Lake Traverse and Big Stone

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 2099

Lake, is continuous with the trough of the Red River of

the North.
Deferring, however, for a little the explanation of this,

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Fie. 53.—Map of Mississippi River from Fort Snelling to Minneapolis and the
vicinity, showing the extent of the recession of the Falls of St. Anthony since
the great Ice age. Notice the greater breadth of the valley of the Minnesota

River as described in the text (Winchell).

9310 MAN AND THE GLACIAL PERIOD.

we will go back to finish the history of the preglacial
channel around the Falls of St. Anthony. As early as
the year 1876 Professor N. H. Winchell had collected suf-
ficient evidence from wells, one of which had been sunk
to a depth of one hundred and seventy-five feet, to show
that the preglacial course of the stream corresponding to
the present Mississippi River ran to the west of Minne-
apolis and of the Falls of Minnehaha, and joined the main
valley some distance above Fort Snelling, as shown in the
accompanying map.

This condition of things was at one time very pain-

fully brought to the notice of the citizens of Minneapolis.
A large part of the wealth of the city at that time con-
sisted of the commercial value of the water-power fur-
nished by the Falls of St. Anthony. ‘To facilitate the
discharge of the waste water from their wheels, some mill-
owners dug a tunnel through the soft sandstone underlying
the limestone strata over which the river falls; but it very
scon became apparent that the erosion was proceeding
with such rapidity that in a few years the recession of
the falls would be carried back to the preglacial channel,
when the river would soon scour out the channel and de-
stroy their present source of wealth. he citizens rallied
to protect their property, and spent altogether as much
es half a million dollars in filling up the holes that had
been thoughtlessly made; but so serious was the task that
they were finally compelled to appeal for aid to the United
States Government. Permanent protection was provided
by running a tunnel, some ways back from the falls, com-
pletely across the channel, through the soft sandstone un-
derlying the limestone, and filling this up with cement
hard enough and compact enough to prevent the further
percolation of the water from above.

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 911

Ice-Dams.

The foregoing changes in lines of drainage due to the
Glacial period were produced by deposits of earthy mate-
rial in preglacial channels. Another class of temporary
but equally interesting changes were produced by the ice
itself acting directly as a barrier.

Many such lakes on a small scale are still in existence
in various parts of the world. The Merjelen See in Switz-
erland is a well-known instance. ‘This is a small body of
water held back by the great Aletsch Glacier, in a little
valley leading to that of the Fiesch Glacier, behind the
Eggischorn. At irregular intervals the ice-barrier gives
way, and allows the water to rush out in a torrent and
flood the valley below. Afterwards the ice closes up again,
and the water reaccumulates in preparation for another
flood.

Other instances in the Alps are found in the Mattmark
See, which fills the portion of the Saas Valley between
Monte Rosa and the Rhéne. This body of water is held
in place by the Allalin Glacier, which here crosses the
main valley. The Lac du Combal is held back by the
Glacier de Miage at the southern base of Mont Blane.
“A more famous case is that of the Gietroz Glacier in the
valley of Bagnes, south of Martigny. In 1818 this lake
had grown to bea mile long, and was 700 feet wide and
200 feet deep. An attempt was made to drain it by cut-
ting through the ice, and about half the water was slowly
drawn off in this way; but then the barrier broke, and
the rest of the lake was emptied in half an hour, causing
a dreadful flood in the valley below. In the Tyrol, the
Vernagt Glacier has many times caused disastrous floods
by its inability to hold up the lake formed behind it. In
the northwestern Himalaya, the upper branches of the
Indus are sometimes held back in this way. <A noted
flood occurred in 1835; it advanced twenty-five miles in

912 MAN AND THE GLACIAL PERIOD.

an hour, and was felt three hundred miles down-stream,
destroying all the villages on the lower plain, and strew-
ing the fields with stones, sand, and mud.*

In Greenland such temporary obstructions are fre-
quent, forming lakes of considerable size. Instances oc-
cur, In connection with the Jakobshavn and the Freder-
ickshaab Glaciers, and in the North Isortok and Alan-
gordlia Fiords. ;

Frequently, also, bodies of water of considerable size
are found in depressions of the ice itself, even at high
levels. I have myself seen them covering more than an
acre, and as much as a thousand feet above the sea-level,
upon the surface of the Muir Glacier, Alaska. ‘They are
reported by Mr. I. C. Russell ¢ of larger size and at still
higher elevations upon the glaciers radiating from Mount
St. Elias; while the explorers of Greenland mention them
of impressive size upon the surface of its continental ice-
sheet.

With these facts in mind we can the more readily
enter into the description which will now be given of
some temporary lakes of vast size which were formed by
direct. ice-obstructions during portions of the period.

One of the most interesting of these is illustrated upon
the accompanying map, which will need little description.

While tracing the boundary-line of the glaciated area
in the Mississippi Valley during the summer of 1882, I
discovered the existence of unmistakable glacial deposits
in Boone County, Kentucky, across the Ohio River, from
Cincinnati.{ These deposits were upon the height of land
550 feet above the Ohio River, or nearly 1,000 feet above

* Professor William M. Davis in. Proceedings of the Boston
Society of Natural History, vol. xxi, pp. 350, 351.

+ See National Geographic Magazine, vol. ii, pp. 116--120.

¢ The existence of portions of this evidence had previously been
pointed out by Mr. Robert B. Warder and Dr. George Sutton (see
Geological Reports of Indiana, 1872 and 1878).

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914 MAN AND THE GLACIAL PERIOD.

the sea, which is about the height of the water-shed be-
tween the Licking and Kentucky Rivers. As the Ohio
River occupies a trough of erosion some hundreds of feet
in depth, and extending all the way from this point to the
mountains of western Pennsylvania, it would follow that
the ice which conveyed boulders across the Ohio River at
Cincinnati, and deposited them upon the highlands be-
tween the Licking and Kentucky Rivers, would so ob-
struct the channel of the Ohio as to pond the water back,
and hold it up to the level of the lowest pass into the
Ohio River farther down. Direct evidences of obstruc- ~
tion by glacial ice appear also for a distance of fifty or
sixty miles, extending both ways, from Cincinnati.

The consequences connected with this state of things
are of the most interesting character.

The bottom of the Ohio River at Cincinnati is 482
feet above the sea-level. A dam of 550 feet would raise
the water in its rear toa height of 982 feet above tide.
This would produce a long, narrow lake, of the width of
the eroded trough of the Ohio, submerging the site of
Pittsburg to a depth of 281 feet, and creating slack water
up the Monongahela nearly to Grafton, West Virginia,
and up the Alleghany as far as Oil City. All the tribu-
taries of the Ohio would hkewise be filled to this level.
The length of this slack-water lake in the main valley, to
its termination up either the Alleghany or the Monon-
gahela, was not far from one thousand miles. The con-
ditions were also peculiar in this, that all the northern
tributaries rose within the southern margin of the ice-
front, which lay at varying distances to the north. Down
these there must have poured during the summer months
immense torrents of water to strand boulder-laden ice-
bergs on the summits of such high hills as were lower
nan the level of the dam.

Naturally enough, this hypothesis of a glacial dam at
Cincinnati aroused considerable discussion, and led to

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 915

some differences of opinion. Professors I. C. White and
J. P. Lesley, whose field work has made them perfectly
familiar with the upper Ohio and its tributaries, at once
supported the theory, with a great number of facts con-
cerning certain high-level terraces along the Alleghany
and Monongahela Rivers; while additional facts of the
same character have been brought to light by myself and
others. In general, it may be said that in numerous
places. terraces occur at a height so closely corresponding
to that of the supposed dam at Cincinnati, that they cer-
tainly strongly suggest direct dependence upon it. The
upward limit of these terraces in the Monongahela River
is 1,065 feet, and they are found in various places in situa-
tions which indicate that they were formed in still water
of such long standing as would require an obstruction be-
low of considerable permanence.

One of the most decisive cases adduced by Professor
White occurs near Morgantown, in West Virginia, of which
he gives the following description :

“Owing to the considerable elevation—275 feet-—of
the fifth terrace above the present river-bed in the vicinity
of Morgantown, its deposits are frequently found far in-
land from the Monongahela, on tributary streams. A
_ very extensive deposit of this kind occurs on a tributary
one mile and a half northeast of Morgantown ; and the re-
gion, which includes three or four square miles, is signifi-
cantly known as the ‘ Flats.’ The elevation of the ‘ Flats’
is 275 feet above the river, or 1,065 feet above tide. The
deposits on this area consist almost entirely of clays and
fine, sandy material, there being very few boulders inter-
mingled. The depth of the deposit is unknown, since a
well sunk on the land of Mr. Baker passed through alternate
beds of clay, fine sand, and muddy trash, to a depth of six-
ty-five feet without reaching bed-rock. In some portions
of the clays which make up this deposit, the leaves of our
common forest-trees are found most beautifully preserved.”

916 MAN AND THE GLACIAL PERIOD.

“ At Clarksburg, where the river unites with Elk Creek,
there is a wide stretch of terrace deposits, and the upper
limit is there about 1,050 feet above tide, or only 130 feet
above low water (920 feet); while at Weston, forty miles
above (by the river), these deposits cease at seventy feet
above low water, which is there 985 feet above tide. It
will thus be observed that the upper limit of the deposits
retains a practical horizontality from Morgantown to Wes-
ton, a distance of one hundred miles, since the upper limit
has the same elevation above tide (1,045 to 1,065 feet) at
every locality.

“These deposits consist of rounded boulders of sand-
stone, with a large amount of clay, quicksand, and other
detrital matter. ‘The country rock in this region consists
of the soft shales and limestones of the upper coal-meas-
ures, and hence there are many ‘low gaps’ from the head
of one little stream to that of another, especially along the
immediate region of the river; and in every case the sum-
mits of these divides, where they do not exceed an eleva-
tion of 1,050 feet above tide, are covered with transported
or terrace material; but where the summits go more than
afew feet above that level we find no transported ma-
terial upon them, but simply the decomposed country
rock.”

Other noteworthy terraces naturally attributable to the
Cincinnati ice-dam are to be found in the valley of the Ka-
nawha, in West Virginia, and one of special significance
on the pass between the valleys of the Ohio and Mononga-
hela, west of Clarksburg, West Virginia. According to
Professor White, there is at this latter place “a broad,
level summit, having an elevation of 1,100 feet, in a gap
about 300 feet below the enclosing hills. This gap, or
valley, is covered by a deposit of fine clay. The cut
through it is about thirty feet, and one can observe the
succession of clays of all kinds and of different colours,
from yellow on the surface down to the finest white pot-

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 917

ter’s clay at the level of the railway, where the cut reaches
bed-rock, thus proving that the region has been sub-
merged.” *

Another crucial case I have myself described at Belle-
vue, in the angle of the Ohio and Alleghany Rivers, about
five miles below Pittsburg, where the gravel terrace is
nearly 300 feet above the river, making it about 1,000
feet above the sea. A significant circumstance connected
with this terrace is that not only does its height corre-
spond with that of the supposed obstruction at Cincin-
nati, but it contains many pebbles of Canadian origin,
which could not have got into the valley of the Alleghany
before the Glacial period, and could only have reached
their present position by being brought down the Alle-
ghany River upon floating ice, or by the ordinary move-
ment of gravel along the margin of ariver. Thus this
terrace, while corresponding closely with the elevation of
those on the Monongahela River, is directly connected
with the Glacial period, and furnishes a twofold argu-
ment for our theory.

A still stronger case occurs at Beech Flats, at the head
of Ohio Brush Creek, in the northwest corner of Pike
County, Ohio, where, at an elevation of about 950 feet
above the sea, there is an extensive flat-topped terrace just
in front of the terminal moraine. ‘This terrace consists of
fine loam, such as is derived from the glacial streams, but
which must have been deposited in still water. ‘The oc-
currence of still water at that elevation just in front of the
continental ice-sheet is best accounted for by the supposed
dam at Cincinnati. Indeed, it is extremely difficult to ac-
count for it in any other way.

There are, however, two other methods of attempting
to account for the class of facts above cited in support of
the ice-dam theory, of which the most plausible is, that in

* Bulletin of the Geological Society of America, vol. i, p. 478.

218 MAN AND THE GLACIAL PERIOD.

connection with the Glacial period there was a subsidence
of the whole region to an extent of 1,100 feet.

The principal objection heretofore alleged against this ~
supposition is that there are not corresponding signs of
still-water action at the same level on the other side of the
Alleghany Mountains. This will certainly be fatal to the
subsidence theory, if it proves true. But it is possible that
sufficient search for such marks has not yet been made on
the eastern side of the mountains.

The other theory to account for the facts is, that the
terraces adduced in proof of the Cincinnati ice-dam were ©
left by the streams in the slow process of lowering their
beds from their former high levels. This is the view
advocated by President T. C. Chamberlin. But the fresh-
ness of the leaves and fragments of wood, such as were
noted by Professor White at Morgantown, and the great
extent of fine silt occasionally resting upon the summits
of the water-sheds, as described above, near Clarksburg,
bear strongly against it. Furthermore, to account for the
terrace described at Bellevue, which contains Canadian
pebbles, President Chamberlin is compelled to connect
the deposit with his hypothetical first Glacial epoch, and
to assume that all the erosion of the Alleghany and
Monongahela Rivers, and indeed of the whole trough of
the Ohio River, took place in the interval between the
“first” and the “second” Glacial periods (for he would
connect the glacial deposits upon the south side of the
river at Cincinnati with the first Glacial epoch)—all of
which, it would seem, is an unnecessary demand upon the
forces of Nature, when the facts are so easily accounted for
by the simple supposition of the dam at Cincinnati.*

* See matter discussed more at length in the Ice Age, pp. 326—
300, 480-500; Bulletin of the United States Geological Survey, No.
58, pp. 76-100 ; Popular Science Monthly, vol. xlv, pp. 184-199. Pez
contra, Mr. Frank Leverett, in American Geologist, vol. x, pp. 18-24.

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220 MAN AND THE GLACIAL PERIOD.

We have already described * the various temporary lakes
and lines of drainage caused by the direct obstruction of
the northward outlets to the basin of the Great Lakes.
In connection with the map, it will be unnecessary to do
anything more here than add a list of such temporary
southern outlets from the Erie-Ontario basin.+ The first
is at Fort Wayne, Indiana, through a valley connecting
the Maumee River basin with that of the Wabash. The
channel here is well defined, and the high-level gravel

terraces down the Wabash River are a marked characteris- _

tic of the valley. The elevation of this col above the sea
is 740 feet. Similar temporary lines of drainage existed
from the St. Mary’s River to the Great Miami, at an eleva-
tion of 942 feet; from the Sandusky River to the Scioto,
through the Tymochtee Gap, at an elevation of 912 feet;
from Black River to the Killbuck (a tributary of the
Muskingum) through the Harrisville Gap, at 911 feet;
from the Cuyahoga into the Tuscarawas Valley, through
the Akron Gap, at 971 feet; from Grand River into the
Mahoning, through the Orwell Gap, 938 feet; from Cat-
taraugus Creek, N. Y., into the Alleghany Valley through
the Dayton Gap, about 1,300 feet; between Conneaut
Creek and Shenango River, at Summit Station, 1,141 feet ;
from the Genesee River, N. Y., into the head-waters of the
Canisteo, a branch of the Susquehanna, at Portageville,
1,314 feet; from Seneca Lake to Chemung River, at
Horseheads, 879 feet; from Cayuga Lake to the valley of
Cayuga Creek, at Spencer, N. Y., 1,000 feet; from Utica,
N. Y., into the Chenango Valley at Hamilton, about 900
feet.

Perhaps it would have been best to give this list
in the reverse order, which would be more nearly chrono-
logical, since it is clear that the highest outlets are the
oldest. We should then have to mention, after the Fort

* See pp. 92 seq., 199 seq. + See also accompanying map.

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 99] 7

MAP OF
CUYAHOGA LAKE.

Area about 55 Sqr, Miles.
Seale, 3 miles to 1 inch.

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Wis kK

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Fie. 56.—Map illustrating a stage in the recession of the ice in Ohio. Fora section of
the deposit in the bed of this lakelet, see page 200. The gravel deposits formed at
this stage along the outlet into the Tuscarawas River are very clearly marked (Clay-
pole). (Transactions of the Edinburgh Geological Society.

48
Summit L. GN 2
ve W/r

999 MAN AND THE GLACIAL PERIOD.

Wayne outlet, two others at lower levels which are pretty
certainly marked by distinct beach ridges upon the south
side of Lake Erie. The first was opened when the ice had
melted back from the south peninsula of Michigan to the
water-shed across from the Shiawassee and Grand Rivers,
uncovering a pass which is now 729 feet above the sea.
This continued to be the outlet of Lake Erie-Ontario until
the ice had further retreated beyond the Strait of Mackinac,
when the water would fall to the level of the old outlet
from Lake Michigan into the Illinois River, which is a _
little less than 600 feet, where it would remain until the
final opening of the Mohawk River in New York attracted
the water in that direction, and lowered the level to that
of the pass from Lake Ontario to the Mohawk at Rome.*

A study of these lines of temporary drainage during
the Glacial period sheds much light upon the long lines
of gravel ridges running parallel with the shores of Lake
Erie and Lake Ontario. South of Lake Erie a series of
four ridges of different elevations can be traced. In Lo-
rain County, Ohio, the highest of these is 220 feet above
the lake; the next 160 feet; the next 118 feet; and the
lower one 100 feet, which would make them respectively
795, 755, 715, and 700 feet above tide.

These gravel ridges are evidently old beach lines, and
indicate the different levels up to which the water was
held by ice-obstructions across the various outlets of the
drainage valley. The material in the ridges is water-worn
and well assorted, and in coarseness ranges from fine sand
up to pebbles several inches in diameter. ‘The predomi-
nant material in them is of local origin. Where the rocks
over which they run are sandstone, the material is chiefly
sand, and where the outcropping rock is shale, the ridges
consist chiefly of the harder nodules of that formation

* Mr. Warren Upham, in the Bulletin of the Geological Society
of America, vol. ii, p. 259.

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 993

which have successfully resisted the attrition of the waves.
Ordinarily these ridges are steepest upon the side facing
the lake. According to Mr. Upham, who has driven over
them with me, the Lake Erie ridges correspond, both in
general appearance and in all other important respects,

Fig. 57.—Section of the lake ridges near Sandusky, Ohio.

to those which he has so carefully surveyed around the
shores of the ancient Lake Agassiz in Minnesota and
Manitoba, an account of which will be given a little far-
ther on in this chapter.

924 MAN AND THE GLACIAL PERIOD.

We are not permitted, however, to assume that there
have been no changes of level since the deposition of these
beaches surrounding the ancient glacial Lake Erie-Ontario.
On the contrary, there appears to have been a considerable
elevation towards the east and northeast in post-glacial
times. The highest ridge south of Lake Erie, which at
Fort Wayne is about 780 feet high, is now about 795 feet
in Lorain County. The second of the ridges above men-
tioned, which is about 740 feet above tide at Cleveland,
Ohio, rises to 870 feet where the last traces of it have been
discovered at Hamburg, N. Y. The third ridge, which is
673 feet at Cleveland, has risen to the height of 860 feet
at Crittenden, about one hundred miles to the east of
Buffalo, N. Y.

A similar eastern increase of elevation is discoverable
in the main ridge surrounding Lake Ontario. What Pro-
fessor Spencer calls the Iroquois beach, which is 363 feet
above tide at Hamilton, Ontario, has risen to a height of
484 feet near Syracuse, N. Y.; while farther to the north-
east, in the vicinity of Watertown, it is upwards of 800
feet above tide.

There is also a similar northward increase of elevation
in the beaches surrounding the higher lands of Ontario
eastward of Lake Huron and Georgian Bay.

All this indicates that at the close of the Glacial period
there was a subsidence of several hundred feet in the area
of greatest ice accumulation lying to the east and north of
the Great Lake region. The formation of these ridges
occurred during that period of subsidence. The re-eleva-
tion which followed the disappearance of the ice of course
carried with it these ridges, and brought them to their
present position.*

In returning to consider more particularly the remark-

* See Spencer, in Bulletin of the Geological Society of America,
vol. ii, pp. 465-476,

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 995

able gorge joining the Minnesota with the Red River of
the North, we are brought to the largest of the glacial
lakes of this class, and to the typical place in America in
which to study the temporary changes of drainage pro-

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described in the text (Upham).

duced by the ice itseif daring the periods both of its ad-
vance and of its retreat.
By turning to our general map of the glaciated region
16

~

298 MAN AND THE GLACIAL PERIOD.

of the United States,* one can readily see the relation of

the valley between Lake Traverse and Big Stone Lake to
an area marked as the bed of what is called Lake Agassiz.
During the Glacial period Brown’s Valley, the depression
joining these two lakes, was the outlet of an immense body
of water to the north, whose natural drainage was towards
Hudson Bay or the Arctic Ocean, but which was cut off,
by the advancing ice, from access to the ocean-level in
that direction, and was compelled to seek an exit to the
south.

Thus for a long period the present Minnesota River
Valley was occupied by a stream of enormous dimensions,
and this accounts for the great size of the trongh—the
present Minnesota being but an insignificant stream wind-
ing about in this deserted channel of the old “ Father of
Waters,” and having as much room as a child of tender
age would have in his parent’s cast-off garments. This
glacial stream has been fittingly named River Warren,
after General Warren, who first suggested and proved its
existence, and so we have designated it on the accompany-
ing map of Minnesota.

Lake Traverse is fifteen miles long, and the water is
nowhere more than twenty feet deep. Big Stone Lake is
twenty-six miles long, and of about the same depth.
Brown’s Valley, which connects the two, is five miles long,
and the lakes are so nearly on a level that during floods
the water from Lake Traverse sometimes overflows and
runs to the south as well as to the north.

The trough occupied by these lakes and valley is from
one mile to one mile and a half in width and about 120
feetin depth. If we had been permitted to stand upon
the bluffs overlooking it during the latter part of the
Glacial period, we should have seen the whole drainage of
the north passing by our feet ou its way to the Gulf of

* See page 66.

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998 MAN AND THE GLACIAL PERIOD.

Mexico. As he follows down the valley of the Minnesota
River, the observant traveller, even now, cannot fail to see in
the nnmerous well-preserved gravel terraces the high-water
marks of that stream when flooded with the joit product
of the annual precipitation over the vast area to the north,
and of the still more enormous quantities set free by the
melting of the western part of the great Laurentide Glacier.

Numerous other deserted water-ways in the north-
western part of the valley of the Mississippi have been
brought to light in the more recent geological surveys,
both in the United States and in Canada. During a con-
siderable portion of the Glacial period the Saskatchewan,
the Assiniboine, the Pembina, and the Cheyenne Rivers,
whose present drainage is into the Red River of the North,
were all turned to the south, and their temporary channels
can be distinctly traced by deserted water-courses marked
by lines of gravel deposits.*

In Dakota, Professor J. E. Todd has discovered large
deserted channels on the southwestern border of the gla-
ciated region near the Missouri River, where evidently
streams must have flowed for a long distance in ice-chan-
nels when the ice still continued to occupy the valley of
the James River. From these channels of ice in which
the water was held up to the level of the Missouri Coteau
the water debouched directly into channels with sides and
bottom of earthy material, which still show every mark of
their former occupation by great streams.t+

In Minnesota, also, there is abundant evidence that
while the northeastern part of the valley from Mankato
to St. Paul was occupied by ice, the drainage was tempo-
rarily turned directly southward across the country through
Union Slough and Blue Earth River into the head-waters
of the Des Moines River in Iowa.

* For further particulars, see Ice Age, pp. 293 et seq.
+ For particulars, see Ice Age, p. 292.

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 999

Ancient River Terraces.

The interest of the whole inquiry respecting the rela-
tion of man to the Glacial period in America concentrates
upon these temporary lines of southern drainage. Wher-
ever they existed, the swollen floods of the Glacial period
have left their permanent marks in the deposition of ex-
tensive gravel terraces. ‘The material thus distributed is
derived largely from the glacial deposits through which
they run and out of which theyemerge. While the height
of the terraces depended upon various conditions which
must be studied in detail, in general it may be said that it
corresponds pretty closely with the extent of the area
whose drainage was turned through the channel during
the prevalence of the ice. The height of the terraces
and the ccarseness of the material seem also to have been
somewhat dependent upon the proximity of their val-
leys to the areas of most vigorous ice-action, and this, in
turn, seems to lie in the rear of the moraines which Presi-
dent Chamberlin has attributed to the second Glacial
epoch. Southward from this belt of moraines the ter-
races uniformly and gradually diminish both in height
and in the coarseness of their gravel, until they finally
disappear in the present flood-plain of the Mississippi
River.

Fig. 60.—Ideal section across a river-bed in drift region: 60, old river-bea;
R, the present river ; ¢¢, upper or older terraces ; ¢’ ¢’, lower terraces.

An interesting illustration of this principle is to be
observed in the continuons valley of the Alleghany and
Ohio Rivers. The trough of this valley was reached by
the continental glacier at only a few points, the ice barely

230 MAN AND THE GLACIAL PERIOD.

touching it at Salamanca, N. Y., Franklin, Pa., and Cin-
cinnati, Ohio. But throughout its whole length the ice-
front was approximately parallel to the valley, and occu-
pied the head-waters of nearly all its tributaries. Now,
wherever tributaries which could be fed by glacial floods,
enter the trough of the main stream, they brought down
an excessive amount of gravel, and greatly increased the
size of the terrace in the trough itself, and from the mouth
of each such tributary to that of the next one below there

is a gradual decrease in the height of the terrace and in -

the coarseness of the material.

This law is illustrated with special clearness in Penn-
sylvania between Franklin and Beaver. Franklin is upon
the Alleghany River, at the last point where it was reached
directly by the ice. Below this point no tributary reaches
it from the glaciated region, and none such reaches the
Ohio after its junction with the Alleghany until we come
to the mouth of Beaver Creek, about twenty-five miles be-
low Pittsburg.

But at this point the Ohio is joimed by a line of drain-
age which emerges from the glaciated area only ten or
twelve miles to the north, and whose branches occupy an
exceptionally large glaciated area. Accordingly, there is at
Beaver a remarkable increase in the size of the glacial ter-
race on the Ohio. In the angle down-stream between the
Beaver and the Ohio there isan enormous accumulation of
granitic pebbles, many of them almost large enough to be
called boulders, forming the delta terrace, wpon which the
eity is built and rising to a height of 135 feet above the
low-water mark in the Ohio. In striking confirmation of
our theory, also, the terrace in the Ohio Valley upon the
upper side of Beaver Creek is composed of fine material,
largely derived from local rocks and containing but few
granitic pebbles.

From the mouth of Beaver Creek, down the Ohio, the
terrace is coristant (sometimes upon one side of the river

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 931

and sometimes upon the other), but, according to rule,
the material of which it is composed gradually grows finer,
and the elevation of the terrace decreases. According to
rule, also, there is a notable increase in the height of the
terrace below each affluent which enters the river from the
glaciated region. This is specially noticeable below Mari-
etta, at the mouth of the Muskingum,.whose head-waters
drain an extensive portion of the glaciated area. From the
mouth of the Little Beaver to this point the tributaries of
the Ohio are all small, and none of them rise within the gla-
cial limit. Hence they could contribute nothing of the gra-
nitic material which enters so largely into the formation
of the river terrace; but below the mouth of the Mus-
kingum the terrace suddenly ascends to a height of nearly
one hundred feet above low-water mark.

Again, at the mouth of the Scioto at Portsmouth, there
is a marked increase in the size of the terrace, which is
readily accounted for by the floods which came down the
Scioto Valley from the glaciated region. The next marked
increase is at Cincinnati, just below the mouth of the
Little Miami, whose whole course lay in the glaciated re-
gion, and whose margin is lined by very pronounced ter-
races. At Cincinnati the upper terrace upon which the
city is built is 120 feet above the flood-plain.

Twenty-five miles farther down the river, near Law-
renceburg, these glacial terraces are even more extensive,
the valley being there between three and four miles wide,
and being nearly filled with gravel deposits to a height of
112 feet above the flood-plain. Below this point the ter-
races gradually diminish in height, and the material be-
comes finer and more water-worn, until it merges at last
in the flood-plain of the Mississippi. ‘The course of the
Wabash River is too long to permit it to add materially to
the size of the terraces which characterise the broader val-
ley of the Ohio below the Illinois line.

It isin terraces such as these just described that we find

932 MAN AND THE GLACIAL PERIOD.

the imbedded relics of man which definitely connect him
with the great Ice age. These have now been found in
the glacial terraces of the Delaware River at Trenton,
N. J.3; in similar terraces in the vailey of the Tuscarawas
River at New Comerstown, and in the valley of the Little
Miami at Loveland and Madisonville, in Ohio; on the
Kast Fork of White River, at Medora, Ind.; and _ still,
again, at Little Falls, in the trough of the Mississippi, some
distance above Minneapolis, Minn.

T append a list of the points at which various streams
from the Atlantic Ocean to the Mississippi River emerge
from the glacial boundary, and below which the terraces
are specially prominent. Of course, with the retreat of the
ice, the formation of the terraces continued northward in
the glaciated area to a greater or less distance, according
to the extent of the valley or to the length of time dur-
ing which the drainage was temporarily turned into it.
These points of emergence are: In the Delaware Valley,
at Belvidere, N. J.; in the Susquehanna, at Beach Haven,
Pa.; in the Conewango, at Ackley, Warren County; in
Oil Creek, above Titusville: in French Creek, a little
above Franklin; in Beaver Creek, at Chewtown, Lawrence
County; on the Middle Fork of Little Beaver, near New
Lisbon, Ohio; on the east branch of Sandy Creek, at Kast
Rochester, Columbiana County; on the Nimishillin, at
Canton, Stark County; on the Tuscarawas, at Bolivar; on
Sugar Creek, at Beech City; on the Killbuck, at Millers-
burg, Holmes County; on the Mohican, near the northeast
corner of Knox County; on the Licking River, at Newark ;
on Jonathan Creek, Perry County; on the Hocking, at
Lancaster; on the Scioto, at Hopetown, just above Chilli-
cothe ; on Paint Creek, and its various tributaries, between
Chillicothe and Bainbridge; and on the Wabash, above
New Harmony, Ind.; to which may be added the Ohio
River itself, at its junction with the Miami, near Lawrence-
burg.

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 933

Another class of terraces having most interesting con-
nection with the Glacial period is found in the aria basins
west of the Rocky Mountains. Over wide areas in Utah
and Nevada the evaporation now just balances the pre-
cipitation, and all the streams disappear in shallow bodies
of salt water of moderate dimensions, of which Great
Salt Lake in Utah, and Mono, Pyramid, and North
Carson Lakes in Nevada, are the most familiar examples.
These occupy the lowest sinks of enclosed basins of great
depth.

But there is abundant evidence that in consequence of
the increased precipitation and diminished evaporation of
the Glacial period one of these basins was filled to the brim
and the other to a depth of several hundred feet. ‘These
former enlargements have been named after the first ex-
plorers of the region, Captains Lahontan and Bonneville,
and are shown on the accompanying sketch map by the
shading surrounding the existing lakes.

Lake Lahontan has been carefully studied by Mr. I. C.
Russell, and has been found to extend from the boundary
of Oregon to latitude 38° 30’ south, a distance of two hun-
dred and sixty miles. The Central Pacific Railroad runs
through its dried-up bed from Golconda to Wadsworth,
a distance of one hundred and sixty-five miles. The ter-
races of the former lake are distinctly traceable at a height
of 700 feet above the present level of Lake Mono.

Lake Bonneville, whose present representative is Great
Salt Lake, is the subject of a recent monograph by Mr. G.
K. Gilbert, from which it appears that this ancient body
of water occupied 19,750 square miles—an area about ten
times that of the present lake. At the time of its maxi-
mum extension its depth was 1,000 feet, while Great Salt
Lake ranges only from fifteen to fifty feet in depth.

The pass through which the discharge finally took
place is at Red Rock, on the Utah and Northern Railroad,
at the head of Cache Valley on the south and the lower

934 MAN AND THE GLACIAL PERIOD.

part of Marsh Creek Valley on the north. During the
long period preceding and accompanying the gradual rise
of water in the Utah basin to the level of the highest ter-

Fie. 61.—Map of the Quaternary Lakes, Bonneville and Lahontan (after Gilbert
and Russell). .
race, Marsh Creek (the upper portion of which comes from
the mountains on the east and turns at right angles) had
been at work depositing a delta of loose material in the
col which separates the two valleys. This deposit rested
upon a stratum of limestone at the bottom of the pass, -
and covered it with sand, clay, and gravel to a depth of
375 feet. Thus, when the water was approaching its up-
per level, the only barrier to prevent its escape was this
unstable accumulation of loose material upon top of the
rock. It would have required, therefore, no prophet’s
eye to predict that the way was preparing for a tremen-
dous débdcle.
The critical point at length wasreached. After remain-
ing nearly at the elevation of the pass for a considerable |
period, during which the 1,000-foot shore-line was formed, 4

PrN Se ae

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 935

the crisis came when the water began to flow northward
towards Snake River. Once begun in such loose material,
the channel rapidly enlarged until soon a stream equal to
Niagara, and at times probably much larger, was pour-
ing northward through the valley heretofore occupied by
the insignificant rivulets of Marsh Creek and the Port
Neuf. It is impossible to tell how rapidly the loose bar-
rier wore away, but there is abundant evidence in the
valley below that not only the present channel of the
lower part of Marsh Creek, but the whole bottom of the
valley for a mile or more in width, was for a considerable
time covered by a rapid stream from ten to twenty feet
in depth, and descending at the rate of thirteen feet to the
mile. Z

The continuance of this flood was dependent upon the
amount of water to be discharged, which, as we have seen,
was that contained in an area of 20,000 square miles, with
a depth of 375 feet. A stream of the size of Niagara
would occupy about twenty-five years in the discharge of
such a mass, and this may fairly be taken as a measure of
the time through which it lasted. When the loose mate-
rial lying above the strata of limestone in Red Rock Pass
had been washed away, the lake then continued at that
level for an indefinite period, with an overflow regulated
by the annual precipitation of the drainage basin. This
stage of the lake, during which it occupied 13,000 square
miles and was 625 feet above its present level, is also
marked by an extensive and persistent shore-line all
around the basin. But, finally, the balance again turned
when the evaporation exceeded the precipitation, and the
vast body of water has since dwindled to its present insig-
nificant dimensions.

My own interest in this discovery of Mr. Gilbert is en-
hanced by the explanation it gives of a phenomenon in
the Snake River Valley which I was unable to solve when
on the ground in 1890. The present railroad town of

236 MAN AND THE GLACIAL PERIOD.

Pocatello is situated just where this flood emerged from
the narrower valley of Marsh Creek and the Port Neuf,
and spread itself out upon the broad plain of the Snake
River basin. The southern edge of the plain upon which
the city is built is a vast boulder-bed covered with a thin
stratum of sand and gravel. Kverywhere, in sinking wells
and digging ditches on the vacant lots and in the streets
of the city, water-worn boulders of a great variety of mate-
rial and sometimes three or four feet in diameter are en-

countered. I was debarred from regarding this as a ter- |

minal moraine, both by the water-worn character of the
boulders and by the absence of any sign of ice-action in the
surrounding mountains, and I was equally debarred from
attributing it to any ordinary stream of water, both by the
size of the boulders and the fact that for a mile or more
up the Port Neuf Valley there isan intervale, forty or fifty
feet below the surface at Pocatello, and occupying the
whole width of the valley, in which there is only gravel
and fine sand, through which the present Port Neuf pur-
sues a meandering course. ‘The upper end of this short
intervale is bounded by the terminus of a basaltic stream
which had flowed down the valley and filled it to a consid-
erable depth, but had subsequently been much eroded, by
violent water-action. |
In the light of Mr. Gilbert’s discoveries, however, every-
thing is clear. The tremendous débdcle which he has
brought within the range of scientific vision would nat-
urally produce just the condition of things which is so
puzzling at Pocatello. Coming down through the restrict-
ed channel with sufficient force to roll along boulders of
great size and to clear them all out from the upper portion
of the valley, the torrent would naturally deposit them
where the current was first checked, a mile below the
lava cliffs. The plunge of the water over these cliffs
would keep a short space below clear from boulders, and
the more mocerate stream of subsequent times would fill

~~

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 937

in the depression with the sand and gravel now occupy-
ing it.

What other effects of this remarkable outburst may be
traced farther down in the Snake River Valley I cannot
say, but it will be surprising if they do not come to light
and help to solve some of the many geological problems
yet awaiting us in this interesting region.

It should have been said that during the formation of
the 625-foot, or so-called Provo shore-line, glaciers de-
scended from the cafions on the west flank of the Wah-
satch Mountains, and left terminal moraines to mark
the coincidence of the Glacial period with that stage
of the enlargement of the lake. Evidences of a similar
coincidence are to be found on the high-level terraces
surrounding Lake Mono, to which glaciers formerly de-
scended from the western flanks of the Sierra Nevada.

The ancient shore-lines surrounding Lakes Bonneville
and Lahontan bear evidence also of various other episodes
in the Glacial period. Evidently there were two periods
of marked increase in the size of the lakes, with an arid
period intervening. During the first rise the level of
Bonneville attained to within ninety feet of the second, and
numerous beaches were formed, and a large amount of
yellow clay deposited. Then it seems to have been wholly
evaporated, while its soluble mineral matter was precipi-
tated, and so mingled with silt that it did not readily re-
dissolve during the second great rise of water. Partly on
this account, and partly through the influence of the out-
let into the Snake River, the lake was nearly fresh during
its second enlargement.

Huropean Facts.

In Chapter VI it came in place to mention many of
the facts connected with the influence of the Glacial pe-
riod upon the drainage systems of Europe. We there dis-
cussed briefly the probable influence of the ice-obstructions

938 MAN AND THE GLACIAL PERIOD.

that extended across the mouths of the Dwina, the Vistula,
the Oder, the Elbe, the Weser, and the Rhine. The
drainage of the obstructed rivers in Russia was perhaps
turned southward into the Caspian and Black Seas, and
then assisted in forming the fertile soil of the plains in the
southern part of that empire.

The obstructed drainage of the German rivers was
probably turned westward in front of the ice through the
Straits of Dover or across the southern part of England.

This was during the climax of the Glacial period ; but later, .

according to Dawkins, during a period in which the land
of the British Isles stood about 600 feet above its present
level, the streams of the eastern coast—namely, “ the
Thames, Medway, Humber, Tyne, and others, joined the
Rhine, the Weser, and the Elbe, to form a river flowing
through the valley of the ocean. In like manner, the
rivers of the south of England and of the north of France
formed a great river flowing past the Channel Islands due
west into the Atlantic, and the Severn united with the rivers
of the south of Ireland ; while those to the east of Ireland
joined the Dee, Mersey Ribble, and Lune, as well as those of
western Scotland, ultimately reaching the Atlantic to the
west of the Hebrides. The water-shed between the vaileys
of the British Channel and the North Sea is represented by
a ridge passing due south from Folkestone to Dieppe, and
that between the drainage area and the Severn and its
tributaries on the one hand, and of the Irish Channel on
the other, by a ridge from Holyhead westward to Dublin.

“This tract of low, undulating land which surrounded
Britain and Ireland on every side consisted not merely of
rich hill, valley, and plain, but also of marsh-land studded
with lakes, ike the meres of Norfolk, now indicated by
the deeper soundings. ‘These lakes were very numerous
to the south of the Isle of Wight and off the coast of Nor-
folk and Suffolk.” *

* Karly Man in Britain, p. 161.

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 939

The evidence first regarded by scientific men to be
demonstrative of the formation of extensive lakes during

fo)

the Glacial period by the direct influence of ice-dams
exists in the Parallel Roads of Glen Roy in Scotland.

Wit
——s

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.—Parallel roads of Glen Roy.

Fie. 62

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the great glen of Scotl

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, three parallel roads or shelves are traced

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of the mount

steep

a perfect horizontality, and continuin

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Seen at a distance

gate

level on the opposite sides of the glen.

they appear like ledges, or roads, cut artificially out of the
sides of the hills; but when we are upon them, we can

scarcely recognize their existence, so uneven is their sur-

94D MAN AND THE GLACIAL PERIOD.

face and so covered with boulders. ‘They are from ten to
sixty feet broad, and merely differ from the side of the
mountain by being somewhat less steep.

“On closer inspection, we find that these terraces are
stratified in the ordinary manner of ailuvial or littoral de-
posits, as may be seen at those points where ravines have
been excavated by torrents. ‘The parallel shelves, there-
fore, have not been caused by denudation, but by the dep-
osition of detritus, precisely similar to that which is dis-
persed in smaller quantities over the declivities of the hills -
above. These hills consist of clay-slate, mica-schist, and
granite, which rocks have been worn away and laid bare
at a few points immediately above the parallel roads. The
lowest of these roads is about 850 feet above the level of
the sea, and the next about 212 feet higher, and the third
82 feet above the second. There is a fourth shelf, which
occurs only in a contignous valley called Glen Gluoy, which
is twelve feet above the highest of all the Glen Roy roads,
and consequently about 1,156 feet above the level of the
sea. One only, the lowest of the three roads of Glen Roy,
is continued through Glen Spean, a large valley with which
Glen Roy unites. As the shelves, having no slope towards
the sea like ordinary river terraces, are always at the same
absolute height, they become continually more elevated
above the river in proportion as we descend each valley ;
and they at length terminate very abruptly, without any
obvious cause, or any change either in the shape of the
ground or in the composition or hardness of the rocks.” *

Early in his career Charles Darwin studied these an-
cient beaches, and ascribed them to the action of the sea
during a period of continental subsidence. In this view
he was supported by the majority of geologists until the
region was visited by Agassiz, who saw at once the true
explanation. If these were really sea-beaches, similar de-

—e -

* Antiquity of Man, pp. 252, 293.

DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 94]

posits should be found at the same elevation on other
mountains than those surrounding Glen Roy. Their
absence elsewhere points, therefore, to some local cause,
which was readily suggested to the trained eye of one like
Agassiz, then fresh from the study of Alpine glaciers,
who saw that these beaches were formed upon the margin
of temporary lakes, held back during the Glacial period
(as the Merjelen See now is) by a glacier which came out
of one glen and projected itself directly across the course
of another, and thus obstructed its drainage. The glacier
of Glen Spean had pushed itself across Glen Roy, as the
great Aletsch Glacier in Switzerland now pushes itself
across the little valley behind the Eggishorn.

CHAPTER VIII.
RELICS OF MAN IN THE GLACIAL PERIOD.

In Glacial Terraces of the United States.

ALTHOUGH the first clear evidence of glacial man was
discovered in Europe, the problem is so much simpler on
the Western Continent that we shall find it profitable to
study the American facts first. We will therefore present
a summary of them at once, and then proceed to the more
obscure problems of European archeology.

The first definite discovery of human relics clearly con-
nected with glacial deposits in America, and of the same
age with them, was made by Dr. C. C. Abbott, at Trenton,
N. J.,in the year 1875. The city of Trenton is built upon
a delta terrace about three miles wide which occurs at the
head of tide-water on the Delaware River. This terrace
bears every mark of having been deposited by a torrential
stream which came down the valley during the closing pe-
riod of the great Ice age. The material of which the ter-
race consists is all water-worn. According to the descrip-
tion of Professor N. 8. Shaler :

“The general structure of the mass is neither that of
ordinary boulder-clay nor of stratified gravels, such as are
formed by the complete rearrangement by water of the
elements of simple drift-deposits. It is made up of boul-
ders, pebbles, and sand, varying in size from masses con-
taining one hundred cubic feet or more to the finest sand
of the ordinary sea-beaches. There is little trace of true
clay in the deposit; there is rarely enough to give the

i \s

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Philadelphya

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SCALE OF MILES

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Struthers

he shading on the Lehi

aded. T
erraces, which are absent from the

The glaciat

Fie. 63.—

ylkill.

eh and Delaware

Schu

a
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944 MAN AND THE GLACIAL PERIOD.

least trace of cementation to the masses. The various ele-
ments are rather confusedly arranged; the large boulders
not being grouped on any particular level, and their major
axes not always distinctly coinciding with the horizon.
All the pebbles and boulders, so far as observed, are smooth
and water-worn, a careful search having failed to show
evidence of distinct glacial scratching or polishing on
their surfaces. The type of pebble is the subovate or dis-
coidal, and though many depart from this form, yet nearly
all observed by me had been worn so as to show that their
shape had been determined by running water. ‘The mate-
rials comprising the deposit are very varied, but all I ob-
served could apparently with reason be supposed to have
come from the extensive valley of the river near which
they lie, except perhaps the fragments of some rather rare
hypogene rocks.”

A conclusive proof of the relation of this Trenton
delta terrace to the Glacial period is found in the fact that
the gravel deposit is continuous with terraces extending
up the trough of the valley of the Delaware to the glaciated

Fic. 64.—Paleolith found by Abbott in New Jersey, slightly reduced.

area and beyond. As, however, the descent of the river-
bed is rapid (about four feet to the mile) from the glacial

RELICS OF MAN IN THE GLACIAL PERIOD. 945

border down to tide-water, the terrace is not remarkably
high, being only about fifteen or twenty feet above the pres-
ent flood-plain. But it is continuous, and similar in com-
position with the great enlargement in the delta at Tren-
ton. Without doubt, therefore, the deposit represents the
overwash gravel of the Glacial period.

Fortunately for science, Dr. C. C. Abbott, whose tastes
for archeological investigations were early developed, had
his residence upon the border of this glacial delta terrace
at Trenton, and as early as 1875 began to find rough-
stone implements of a peculiar type in the talus of the bank
where the river was undermining the terrace. In turn-
ing his attention to the numerous fresh exposures of gravel
made by railroad and other excavations during the follow-
ing year, he found several of the implements in undisturbed
strata, some of which were sixteen feet below the surface.
Since that time he has continued to make discoveries at
various intervals. In 1888 he had found four hundred
implements of the palexolithic type at Trenton, sixty of
which had been taken from recorded depths in the gravel,
two hundred and fifty from the talus at the bluff facing

a b Cc b a

Fic. 65.—Section across the Delaware River at Trenton, New Jersey: @, @,
Philadelphia red gravel and brick clay (McGee’s Columbia deposit); 0, 0,
Trenton gravel, in which the implements are found: c¢, present flood-plain of
the Delaware River (after Lewis). (From Abbott’s Primitive Industry.)

the river, and the remainder from the surface, or derived
from collectors who did not record the positions or circum-
stances under which they were found.

The material from which the implements at Trenton
are made is argillite—that is, a clay slate which has been
so metamorphosed as to be susceptible of fracture, almost
like flint. It is, however, by no means capable of being
worked into such delicate forms as flint is. But as it is

946 MAN AND THE GLACIAL PERIOD.

the only material in the vicinity capable of being chipped,
prehistoric men of that vicinity were compelled to make a

Fig. 66.—Section of the Trenton gravel in which the implements described in
the text are found. The shelf on which the man stands is made in process
of excavation. The gravel is the same above and below (photograph by
Abbott).

virtue of necessity and use the inferior material. Of all
the implements found by Dr. Abbott in the gravel, only
one was flint; while upon the surface innumerable arrow-
heads of flint have been found. The transition, also, in
the type of implements is as sudden as that in the kind of
material of which they are made. Below the superficial
deposit of black soil, extending down to the depth of about
one foot, the modern Indian flint implements entirely

RELICS OF MAN IN THE GLACIAL PERIOD. 9247

disappear, and implements of paleolithic type only are
found.

Ry
3
BAY
‘ney, Z,,
a:
‘@
g \
: Al
4 7 nes >
At,
Use No
if Bare
ae
A‘ ,
NS daw
ae :
YH
\

rap sa
DS
Pro.

Fig. 67.—Face view of argillite implement, found by Dr. C. C. Abbott, in 1876,
at Trenton, New Jersey, in gravel, three feet from face of bluff, and twenty-
two feet from the surface (No. 10,985) (Putnam).

In the year 1882, after I had traced the glacial bound-
ary westward from the Delaware River, across the States
of Pennsylvania, Ohio, and Indiana, I was struck with

Q48 MAN AND THE GLACIAL PERIOD.

the similarity between the terrace at Trenton and numer-
ous terraces which I had attributed to the Glacial age in

a 6

z *:-- ) UR Es ame ™ SS ee
- F y - 7 / ts, cS 7 7 : — - 3
ok on errs - - e ns ar 7 o a
nie dae ; mY

ma SEES

WE cam.

che

Fie. 68.—Argillite implement found by Dr. C. C. Abbott, March, 1879, at A. K.
Rowan’s farm, Trenton, New Jersey, in gravel sixteen feet from surface : a,
face view; 0, side view (No. 11,286) (Putnam).

Ohio and the other States. It adds much to the interest
of subsequent discoveries to note that in 1884, in my re-
port to the Western Reserve Historical Society upon the
glacial boundary of Ohio, I wrote as follows:

“The gravel in which they [ Dr. Abbott’s implements]
are found is glacial gravel deposited upon the banks of the
Delaware when, during the last stages of the Glacial pe-
riod, the river was swollen with vast floods of water from
the melting ice. Man was on this continent at that period

RELICS OF MAN IN THE GLACIAL PERIOD. 949

when the climate and ice of Greenland extended to the
mouth of New York Harbor. The probability is, that if
he was in New Jersey at that time, he was also upon the
banks of the Ohio, and the extensive terrace and gravel

FIs. 69.—Chipped pebble of black chert, found by Dr. C. L. Metz, October, 1885,
at Madisonville, Ohio, in gravel eight feet from surface under clay: a, face
view; 8, side view.

deposits in the southern part of our State should be closely

scanned by archeologists. When observers become famil-

lar with the rude form of these paleolithic implements,
they will doubtless find them in abundance. But whether
we find them or not in this State [Ohio], if you admit, as

Iam compelled to do, the genuineness of those found by

Dr. Abbott, our investigation into the glacial phenomena

of Ohio must have an important archeological significance,

for they bear upon the question of the chronology of the

Glacial period, and so upon that of man’s appearance in

New Jersey.”

The expectation of finding evidence of preglacial man

in Ohio was justified soon after this (in 1885), when Dr. C

MAN AND THE GLACIAL PERIOD.

250

L. Metz, while co-operating with Professor F. W. Putnam,
of the Peabody Museum, Cambridge, Mass., in field work,

discovered a flint implement of paleolithic type in undis-

turbed strata of the glacial terrace of the Little Miami —

River, near his residence at Madisonville, Ohio.

In 1887

Dr. Metz found another implement in the terrace of the

\

Miller:

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—<—> =

re

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ele

ANN

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SCALE OF MILES

60

40

20

Fie. 70.

The implement at Madisonville occurred

same river, at Loveland, about twenty-five miles farther
eight feet below the surface, and about a mile back from

up the stream.

RELICS OF MAN IN THE GLACIAL PERIOD. 951

the edge of the terrace; while that at Loveland was
found in a coarser deposit, about a quarter of a mile back
from the present stream, and thirty feet below the surface.
Mastodon-bones also were discovered in close proximity to
the implement at Loveland.

Interest in these investigations was still further in-
ereased by the report of Mr. Hilborne TT. Cresson, of
Philadelphia, that in 1886, with my map of the gla-
ciated region in hand, he had found an implement of
paleolithic type in undisturbed strata of the glacial ter-
race bordering ‘the East Branch of White River, near
the glacial boundary at Medora, Jackson County, Ind.
The terrace was about fifty feet above the flood-plain of
the river.

Later still, in October, 1889, Mr. W. C. Mills,.of New-
comerstown, Tuscarawas County, Ohio, found in that town
a finely shaped flint implement sixteen feet below the sur-
face of the terrace of glacial gravel which lines the margin
of the Tuscarawas Valley.* Mr. Mills was not aware of the
importance of this discovery until meeting with me some
months later, when he described the situation to me,
and soon after sent the implement for examination. In
company with Judge C. C. Baldwin, President of the
Western Reserve Historical Society, and several others, a
visit was made to Mr. Mills, and we carefully examined
the gravel-pit in which the implement occurred, and col-
lected evidence which was abundant to corroborate all
his statements. ‘The implement in question is made from
a peculiar flint which is found in the Lower Mercer lime-
stone, of which there are outcrops a few miles distant, and
it resembles in so many ways the typical implements found
by Boucher de Perthes, at Abbeville, that, except for the
difference in the material from which it is made, it would
be impossible to distinguish it from them. The similarity

* For typical section of a glacial terrace in Ohio, see p, 227.

952, MAN AND THE GLACIAL PERIOD.

of pattern is too minute to have originated except from
imitation.

In 1877, a year after the discoveries by Dr. Abbott in
New Jersey, some rude quartz implements were discovered

Fie. 71.—The smaller is the paleolith from Newcomerstown, the larger from
Amiens (face view), reduced one half in diameter.

by Professor N. H. Winchell in the glacial terraces of the
upper Mississippi, in the vicinity of Little Falls, Morrison
County, Minn. This locality was afterwards more fully

RELICS OF MAN IN THE GLACIAL PERIOD. 953

explored by Miss Franc E. Babbitt, who succeeded in find-
ing so large a number of the implements as to set at rest

Fic. 72.—Edge view of the preceding.

all question concerning their human origin. According
to Mr. Warren Upham, the glacial flood-plain of the Mis-
sissippi 1s here about three miles wide, with an elevation of
from twenty-five to thirty feet above the river. It is in
a stream near the bottom of this glacial terrace that the
most of Miss Babbitt’s discoveries were made, and Mr.

954 MAN AND THE GLACIAL PERIOD.

Upham has pretty clearly shown that the gravel of the
terrace overlying them was mostly deposited while the ice-

Ww.
Moditied Drift el ohavezle rivers

Stratum Shippines) oe of ‘Mo difeed Dri if, E D

. Mississippi

Fig. 73. ween across the Mississippi Valley at Little Falls, Minnesota, show-
ing the stratum in which chipped quartz fragments were found by Miss F. E.
Babbitt, as described in the text (Upham).

front was still lingering about sixty miles farther north,
in the vicinity of Itasca Lake.*

Up to this time the above are all the instances in which
the relics of man are directly and indubitably connected
with deposits of this particular period east of the Rocky
Mountains. Probably it is incorrect to speak of these as
preglacial, for the portion of the period at which the de-
posits incorporating human relics were made is well on
towards the close of the great Ice age, since these terraces
were, In some cases, and may have been in all cases, depos-
ited after the ice-front had withdrawn nearly, if not quite,
to the water-shed of the St Lawrence basin. It may be
difficult to demonstrate this with reference to the gravel
deposits at Trenton, Madisonville, and Medora, but it is
evident at a glance in the case of Newcomerstown and
Little Falls.

That the implement-bearing gravel of Trenton, N. J.,
belongs to the later stages of the Glacial period is evident
from its relation to what Professor H. Carvill Lewis called
“the Philadelphia red gravel and brick-clay,” but which,
from its large development in the District of Columbia at
Washington, is called by Mr. McGee the “ Columbia de-
posit.” The city of Philadelphia is built upon this forma-
tion in the Delaware Valley, and the brick for its houses
is obtained from it; the cellar of each house ordinarily
furnishing clay enough for its brick walls. This clay is

>

* For a general map, see p. 66; also p. 225.

RELICS OF MAN IN THE GLACIAL PERIOD. 955

of course a deposit in comparatively still water, which
would imply deposition during a period of land subsidence.

Fig. 74.—Quartz implement, found by Miss F. E. Babbitt, 1878, at Little Falls,
Minnesota, in modified drift, fifteen feet below surface: a, face view; 0,
profile view. The black represented on the cut is the matrix of the quartz
vein (No. 31,823) (Putnam).

But that it was ice-laden water which flooded the banks is
shown by the frequent occurrence of large blocks of stone
in the deposits, such as could have been transported only

256 MAN AND THE GLACIAL PERIOD.

in connection with floating ice. The boulders in the
Columbia formation clearly belong to the individual river
valleys in which they are found, and doubtless are to be
connected with the flooded condition of those valleys
when, by means of a northerly subsidence, the gradient of
the streams was considerably less than now.

There is some difference of opinion in respect to the
extent of this subsidence, and, indeed, respecting the
height attained by the Philadelphia brick-clay, or McGee’s
Columbia deposit. Professor Lewis (whose residence was.
at Philadelphia, and who had devoted much time to field
observations) insisted that the deposit could not be found
higher than from 180 to 200 feet above the immediate
flood-plain of the river valleys where they occur. But,
without entering upon this disputed question, it is suffi-
cient to consider the bearing of the facts that are accepted
by all—namely, that towards the close of the Glacial period
there was a marked subsidence of the land on the eastern
coast of North America, increasing towards the north.

Fully to comprehend the situation, we need to bring
before the mind some of the indirect effects of the Glacial
period in this region. ‘The most important of these was
the necessary projection of subglacial conditions over a
considerable belt of territory to the south of that actually
reached by glacial ice; so that, while there are no clear
indications of the existence of local glaciers in the Appa-
lachian Mountains south of the central part of Pennsyl-
vania, there are many indications of increased snowfall
upon the mountains, connected with prolonged winters and
with a great increase of spring floods and ice-gorges upon
the annual breaking up of winter.

These facts have been stated in detail by Mr. McGee,*
from whose report it appears that, on the Potomac at

* Seventh Annual Report of the United States Geological Survey
for 1885 and 1886, pp. 587-646.

RELICS OF MAN IN THE GLACIAL PERIOD. 957

Washington, the surface of the Columbia deposit is 150
feet above tide, and that the deposit itself contains many
boulders, some of which are as much as two or three feet in
diameter. hese are mingled with the gravel in such a
way as to show that they must have been brought down by
floating ice from the head-waters of the Potomac when the
winters were much more severe than now. ‘That this de-
posit is properly the work of the river is shown by the en-
tire absence of marine shells.

According to Mr. McGee, also, there is a gradual de-
crease in the height of these delta terraces of the Columbia
period as they recede from the glacial boundary—that at
the mouth of the Susquehanna being 245 feet, that of the
Potomac 140 feet, that on the Rappahannock 125, that on
the James 100, and that on the Roanoke 75; while the
size of the transported boulders along the streams also
gradually diminishes in the same order. During the
Columbia period the Susquehanna River transported
boulders fifty times the size now transported, while the
Potomac transported them only up to twenty times, the
Rappahannock only ten times, the James only five, and
the Roanoke only two or three times the size of those now
transported. ‘This progressive diminution, both in the
extent of the deposit and in the coarseness of the material
deposited by these rivers at about the time of the maxi-
mum portion of the Glacial period, is what would naturally
be expected under the conditions supposed to exist in con-
nection with the great Ice age, and is an important con-
firmation of the glacial theory

That the period of subsidence and more intense glacial
conditions during which the Columbia deposits took place,
preceded, by a long interval, the deposition of the gravel
terraces at Trenton, N. J., and the analogous deposits in
the Mississippi Valley where paleeolithic implements have
been found, is evident enough. The Trenton gravel was
deposited in a recess in the Columbia deposit which had

258 MAN AND THE GLACIAL PERIOD.

been previously worn out by the stream. Indeed, in every
place where opportunity offers for direct observation the
Trenton gravel is seen to be distinctly subsequent to the
other. It was not buried by the Philadelphia red gravel and
brick-clay, but to a limited degree overlies and buries it.

The data for measuring the absolute length of time
between these two stages of the Glacial period are very
indefinite. Mr. McGee, however, supposes that since the
Columbia period a sufficient time has elapsed for the falls
of the Susquehanna to recede more than twenty miles
and for those of the Potomac eighteen miles, and this
through a rock which is exceedingly obdurate. But, in
channels opening, as these do, freely outward, it is diffi-
cult to tell in what epochs the erosion has been principally
performed, since there are no buried channels, as in the
glaciated area, enabling us to determine whether or not
much of the eroding work of the river may have been ac-
complished in preglacial times.

The lapse of time which, upon the least calculation,
separates the Columbia epoch from the Trenton, gives
unusual importance to any discovery of paleolithic imple-
ments which may be made in the earlier deposits. We
are bound, therefore, to consider with special caution the
reported discovery of an implement in these deposits at
Claymont, Delaware. The discovery was made by Dr.
Hilborne T. Cresson, on July 13, 1887, during the prog-
ress of an extensive excavation in constructing the Balti-
more and Ohio Railroad, nineteen miles south of Phila-
delphia. The implement was from eight to nine feet
below the surface. As there is so much chance for error
of judgment respecting the undisturbed condition of the
strata, and as there was so little opportunity for Dr. Cres-
son to verify his conclusion, we may well wait for the cumu-
lative support of other discoveries before building a theory
upon it; still, it will be profitable to consider the situation.

Both Mr. McGee and myself have visited the locality
with Dr. Cresson, and there can be no doubt that the

RELICS OF MAN IN THE GLACIAL PERIOD. 959

implement occurred underneath the Columbia gravel.
The line of demarcation is here very sharp between that

=

Fie. 75.—Argillite implement, found by H. T. Cresson, 1887, in Baltimore and
Ohio Railroad cut, one mile from Claymont, Delaware, in Columbia gravel,
eight to nine feet below the overlying clay bed: a, face view; 0, side view
(No. 45,726) (Putnam).

gravel and the decomposed strata of underlying gneiss

rock, which appears in our illustration as a light band in

the middle of the section exposed. Some large boulders
which could have been moved only in connection with
floating ice are found in the overlying deposit near by.

This excavation is about one mile and a half west of the

‘(uosseip Aq ydvisojoyd wodry) 7x0} oy) Ur
poinsy syuewordut oryytjowred punoy uosserg ‘ay O1OYM ‘BMV “WUOWATID vou ‘ynd OIYO puR sIOMITe| JO worq008

JO MOIA [RIdU0H—*9), ‘NIT

RELICS OF MAN IN THE GLACIAL PERIOD. 961

Delaware River, and about 150 feet above it, being nearly
at the uppermost limit of the Columbia deposit in that
vicinity.

The age of these deposits in which implements have
been found at Claymont and at Trenton will be referred
to again when we come to the specific discussion of the
date of the Glacial period. It is sufficient here to bring
before our minds clearly, first, the fact that this at Clay-
mont is connected with the river floods accompanying the
ice at its time of maximum extension, and when there was
a gradually increasing or differential depression of the
country to an unknown extent to the northward.

T'wo radically different theories are presented to account
for the deposits variously known as the Columbia gravel
and the Philadelphia brick-clay. Mr. McGee, in the
monograph above referred to, supposes them to have been
deposited during a period of a general subsidence of the
coast-line; so that they took place at about tide-level. Mr.
Upham, on the other hand, supposes them to have been
deposited during the period of general elevation to whose
influence he mainly attributes the Glacial period itself.
In his view much of the shallow sea-bottom adjoining the
present shore off from Delaware and Chesapeake Bays
was then a land surface, and the Hudson, the Delaware,
and the Susquehanna Rivers, coming down from the still
higher elevations of the north, flowed through extensive
plains so related to the northern areas of elevation that
deposition was occurring in their valleys, owing in part to
the flooded condition of the streams, in part to the differ-
ential elevation, and in part to the superabundance of silt
and other débris furnished by the melting ice-sheet in the
head-waters of these streams.

The deposits of Trenton gravel occurred much later,
at a time when the tce had melted far back towards the
head-waters of the Delaware, and after the land had

nearly resumed its present relations of level, if indeed
18

262 MAN AND THE GLACIAL PERIOD.

it had not risen northward to a still greater relative
height.

As would be expected from the climatic conditions
accompanying the Glacial epoch, man’s companions in the
animal world were very different during the period when
the high-level river gravels of America were forming from
those with which he is now associated. From the remains
actually discovered, either in these gravels or in close prox-
imity to them, we infer that, while the mastodon was the
most frequent of the extinct quadrupeds with which man |
then had to contend in that region, he must have been
familiar also with the walrus, the Greenland reindeer, the
caribou, the bison, the moose, and the musk ox.

In the Glacial Terraces of Europe.

The existence of glacial man in Europe was first de-
termined in connection with the high-level river gravels
already described in the valley of the Somme, situated in
Picardy in the northern part of France. Here in 1841
Boucher de Perthes began to discover rudely fashioned
stone implements in undisturbed strata of the gravel ter-
races, whose connection with the Glacial period we have
already made clear. But for nearly twenty years his dis-
coverles were ignored by scientific men, although he made
persistent efforts to get the facts before them, and pub-
lished a full account of them with illustrations as early as

woSSSSssiscterereeeoeeesaes SSS

Fig. 77.—Section across valley of the Somme: 1, peat, twenty to thirty feet
thick, resting on gravel, @: 2, lower-level gravels, with elephant-bones and
flint implements, covered with river-loam twenty to forty feet thick; 8,
upper-level gravels, with similar fossils covered with loam, in all, thirty feet
thick ; 4, upland- -loam, five to six feet thick ; 5, Eocene-Tertiary.

1847. Some suggested fraud on the part of the workmen ;
others without examination declared that the gravel must

RELICS OF MAN IN THE GLACIAL PERIOD. 9683

have been disturbed; while others, still, denied altogether
the artificial character of the implements.

At length, Dr. Regillout, an eminent physician resid-
ing at Amiens, about forty miles higher up the Somme
than Abbeville, visited Boucher de Perthes, and, upon see-
ing the similarity between the gravel terraces at Abbeville
and Amiens, returned home to look for similar implements
in the high-level gravel-pits at St. Acheul, a suburb of
Amiens. Almost immediately he discovered flint imple-
ments there of the same pattern with those at Abbeville,
and in undisturbed strata of the gravel terrace, where it
rested on the original chalk formation, at a height of 90
feet above the river. In the course of four years, Dr. Reg-
illout found several hundred of these implements, and in

1854 published an illustrated report upon the discoveries.
| Still the scientific world remained incredulous until
the years 1858 and 1859, when Dr. Falconer, Mr. Prest-
wich, Mr. John Evans, Mr. Flower, Sir Charles Lyell, of
England, and MM. Pouchet and Gaudry, of France, visit-
ed Abbeville and Amiens, and succeeded in making similar
discoveries for themselves. Additional discoveries at St.
Acheul have continued up to the present time whenever
excavations have gone on at the gravel-pits. Mr. Prest-
wich estimates that there is an implement to every cubic
metre of gravel, and says that he himself has brought away
at different times more than two hundred specimens, and
that the total number found in this one locality can hardly
be under four thousand. “The gravel-beds are on the
brow of a hill 97 feet above the river Somme,” and besides
the relics of man contain numerous fluviatile and land
shells together with “teeth and bones of the mammoth,
rhinoceros, horse, reindeer, and red deer, but not of the
hippopotamus,” * bones of the latter animal being found
here only in the gravels of the lower terraces, where they

* Prestwich’s Geology, vol. ii, p. 481.

264 MAN AND THE GLACIAL PERIOD.

are less than thirty feet above the river, and mark a con-
siderably later stage in the erosion of the valley. While
many of the implements found at Amiens seem to have
been somewhat worn and rolled, “others are as sharp and.
fresh as when first made. . . . The bedding of the gravel is
extremely irregular and contorted, as though it had been
pushed about by a force acting from above; and this, to-
gether with the occurrence of blocks of Tertiary sandstone
of considerable size, leads to the inference that both are
due to the action of river-ice. In the Seine Valley blocks .
of still larger size, and transported from greater distances,
are found in gravels of the same age.”

“ Klint implements are found under similar conditions
in many of the river-valleys of other parts of France, es-
pecially in the neighbourhood of Paris; of Mons in Bel-
gium ; in Spain, in the neighbourhood of Madrid, in Port-
ugal, in Italy, and in Greece; but they have not been dis-
covered in the drift-beds of Denmark, Sweden, or Russia,
nor is there any well-authenticated instance of the occur-
rence of paleoliths in Germany.” *

When once the fact had been established that man was
in northern France at the time of the deposition of the
high-level gravels of the Somme and the Seine, renewed
attention was directed to terraces of similar age in south-
ern England. One of these is that upon which the city
of London is built, and which, according to Lyell’s descrip-
tion, “extends from above Maidenhead through the me-
tropolis to the sea, a distance from west to east of fifty
miles, having a width varying from two to nine miles. Its
thickness ranges commonly from five to fifteen feet.” +

For a long time geologists had been familiar with the
fact that these terraces of the Thames contain the remains
of numerous extinct animals, among which are included

* Prestwich’s Geology, vol. ii, pp. 481, 482.
+ Antiquity of Man, pp. 154, 155.

RELICS OF MAN IN THE GLACIAL PERIOD. 965

the mammoth and a species of rhinoceros. Upon direct-
ing special attention to the subject, it was found that, at
various intervals, the remains of man, also, had been re-
ported from the same deposits. As long ago as 1715 Mr.
Conyers discovered a paleolithic implement, in connection
with the skeleton of an elephant, at Black Mary’s, near
Gray’s Inn Lane, London. This implement is preserved
in the British Museum, and closely resembles typical speci-
mens from the gravel at Amiens. Other implements of
similar character have been found in the valley of the
Wey near Guilford, aiso in the valley of the Darent, near
Whitstable in Kent, and between Herne Bay and the Re-
culvers. While the exact position of these implements in
the gravel had not been so positively noted as in the case
of those found at Amiens and Abbeville, there can be little
doubt that man, in company with the extinct animals
mentioned, inhabited the valley of the Thames at a period
when its annual floods spread over the whole terrace-plain
upon which the main part of London is built.

In the valley of the Ouse, however, near Bedford, the
discovery of paleeolithic implements in the gravel terraces
connected with the Glacial period and in intimate associa-
tion with bones of the elephant, rhinoceros, hippopotamus,
and other extinct animals, has been as fully established as
in the valley of the Somme. ‘The discoveries here were
first made in the year 1860, by Mr. James Wyatt, in a
eravel-pit at Biddenham, two miles northwest of Bedford.
Two flint implements were thrown out by workmen in one
day from undisturbed strata thirteen feet below the sur-
face, and numerous other specimens have since been found
in a similar situation.

The valley of the Ouse is bordered on either side by
sections of a superficial blanket of glacial drift containing
many transported boulders of considerable size. The val-
ley is here about two miles wide, and ninety feet deep.
The gravel deposit, however, in which the implements

266 MAN AND THE GLACIAL PERIOD.

were found, is only about thirty feet above the present
level of the river, and hence represents the middle period
of the work of the river in erosion.

Another locality in England in which similar discov-
eries have been made, is at Hoxne, about five miles from
Diss, in Suffolk County. Like that in the valley of the
Thames, however, the implements were found a long time
before the significance of the discovery was recognized.
Mr. John Frere reported the discovery to the Society of
Antiquaries in 1801, and gaye some of the implements -
both to the society and to the British Museum, in whose
collections they are still preserved. ‘The implements are of
the true paleolithic type, and existed in such abundance,
and were so free from signs of wear, that the conclusion
seemed probable that a manufactory of them had been
uncovered. As many as five or six to the square yard are
said to have been found. Indeed, their numbers were so
ereat that the workmen “had emptied baskets of them
into the ruts of the adjoining road before becoming aware
of their value.”

The deposit in which they are found is situated in the
valley of Gold Brook, a tributary of the Waveney. The
implements occurred about twelve feet below the surface,
in fresh-water deposits, filling a hollow eroded in the
glacial deposit covering that part of England. This,
therefore, is clearly either of post-glacial or of late glacial
age.

Still another locality in which similar paleeolithic im-
plements were found in undisturbed gravel of this same
age in eastern England is Icklingham, in the valley of the
Lark, where the situation is quite similar to that already |
described at Bedford, on the Ouse.

The last place we will stop to mention in England
which was visited by paleeolithic man, during or soon after
the Glacial epoch, is to be found in the vicinity of South-
ampton. At this time the Isle of Wight was joined to the

RELICS OF MAN IN THE GLACIAL PERIOD. 967

mainland, and notimprobably England itself to the Conti-
nent. The river, then flowing through the depression of
the Solent and the Southampton Water, occupied a much
higher level than now, leaving terraces along the shore at
various places, in which the tools of paleolithic man have
been discovered.

Though these are the best authenticated discoveries
connecting man with the Glacial period in England, they
are by no means the only probable cases. Almost every
valley of southern England furnishes evidence of a similar
but less demonstrative character.

In Cave Deposits.

The discovery of the remains of man in the high-level
river-gravels deposited near the close of the Glacial period
led to a revision of the evidence which had from time to
time been reported connecting the remains of man with
those of various extinct animals in cave deposits both in
England and upon the Continent.

The British Isles.

As early as 1826, Rev. J. MacEnery, a Roman Catholic
priest residing near Torquay, in Devonshire, England, had
made some most remarkable discoveries in a cavern at
Kent’s Hole, near his home; but, owing to his early death,
and to the incredulity of that generation of scientific men,
his story was neither credited nor published till 1859.
About this time, a new cave having been discovered not
far away, at Brixham, the best qualified members of the
Royal Society (yell, Phillips, Lubbock, Evans, Vivian,
Pengelly, Busk, Dawkins, and Sanford) were deputed to
see that it was carefully explored. Mr. Pengelly, who had
had twenty years’ experience in similar explorations, di-
rected and superintended the work. Every portion of the
contents was examined with minutest care. Kent’s Hole

968 MAN AND THE GLACIAL PERIOD.

is “180 to 190 feet above the level of mean tide, and
about 70 feet above the bottom of the valley immediately
adjacent.” * In one chamber the excavation was about
sixty feet square. The contents were arranged in the fol-
lowing order:

Fie. 78.—Mouth of Kent’s Hole.

1. A surface of dark earth a few inches thick, contain-
ing Roman pottery, iron and bronze spear-heads, together
with polished stone weapons. There were, too, in this
stratum bones of cows, goats, and horses, mingled with
large quantities of charcoal.

* Dawkins’s Cave-Hunting, p. 820.

RELICS OF MAN IN THE GLACIAL PERIOD. 969

2. Below this was a stalagmite floor from one to three
feet thick, formed by the dripping of lime-water from the
roof.

3. Under this crust of stalagmite was a compact deposit
of red earth, from two to thirteen feet thick.* Flint im-
plements of various kinds and charcoal were also found at
different depths; also an awl, or piercer; a needle with
the eye large enough to admit small pack-thread; and
three harpoon-heads made out of . bone and deer’s
horn.

4, Flint implements were also obtained in a conglom-
erate (breccia) still below this. The fossil bones in this
cave belonged to the same species of animals as those dis-
covered in a cave near Wells.

The Brixham cave occurs near the small village of
that name, not far from Torquay. The entrance to it is
about ninety-five feet above high water. Its deposits, in
descending order, are: 1. Stalagmitic floor from six to
twelve or fifteen inches in thickness. 2. A thin breccia
of limestone fragments cemented together by carbonate of
lime. This had accumulated about the mouth, so as to
fill up the entrance. 3. A layer of blackish earth about
one foot in thickness 4. “ A deposit of from two to four
feet thick, consisting of clayey loam, mingled with frag-
ments of limestone, from small bits up to rocks weighing
aton. Rounded pebbles of other material were also occa-
sionally met with. 5. Shingle consisting of rounded peb-
bles largely of foreign material.

All these strata, except the third, contained fossils of
some kind, but the fourth was by far the richest repository.
Among the bones found are those of the mammoth, the
woolly rhinoceros, the horse, the ox, the reindeer, the cave
lion, the cave hyena, and the cave bear. Associated with

* Dawkins’s Cave-Hunting, p. 826; Lyell’s Antiquity of Man,
p. 101.
19

970 MAN AND THE GLACIAL PERIOD.

these remains a number of worked flints was found. In
one place the bones of an entire leg of a cave bear occurred
in such a position as to show that they must have been
bound together by the ligaments when they were buried.
Immediately below these bones a flint implement was
found.*

The hyena’s den, at Wookey Hole, near Wells, in Som-.

erset, was carefully explored by Professor Boyd Dawkins,
who stood by and examined every shovelful of material as
it was thrown out.

This cave alone yielded 35 specimens of paleolithic |

art, 467 jaws and teeth of the cave hyena, 15 of the cave
lion, 27 of the cave bear, 11 of the grizzly bear, 11 of the
brown bear, 7 of the wolf, 8 of the fox, 30 of the mam-
moth, 233 of the woolly rhinoceros, 401 of the horse, 16 of
the wild ox, 30 of the bison, 35 of the Irish elk, and 30 of
the reindeer (jaws and teeth only).

In Derbyshire numerous caves were explored by Pro-
fessor Dawkins at Cresswell Crags, which, in addition to
flint implements and the remains of the animals occurring
in the Brixham caye, yielded the bones of the machairodus,
an extinct species of tiger or lion which lived during the
Tertiary period.

The Victoria cave, near Settle, in west Yorkshire, is
the only other one in England which we need to mention.
In this there were no remains found which could be posi-

tively identified as human, but the animal remains in the

lower strata of the cave deposit were so different from those
in the upper bed as to indicate the great lapse of time
which separated the two. This cave is 1,450 feet above the
sea-level, and there were found in the upper strata of the
floor, down to a depth of from two to ten feet, many re-
mains of existing animals. Then, for a distance of twelve
feet, there occurred a clay deposit, containing no organic re-

* See Pengelly’s Reports to the Devonshire Association, 1867.

RELICS OF MAN IN THE GLACIAL PERIOD. 971

mains whatever, but some well-scratched boulders. Below
this was a third stratum of earth mingled with limestone
fragments, at the base of which were numerous remains
of the mammoth, rhinoceros, hippopotamus, bison, hyena,
etc. One bone occurred which was by some supposed to
be human,-but by others to have belonged to abear. This
lower stratum is, without much doubt, preglacial, and the
thickness of the deposit intervening between it and the
upper fossiliferous bed is taken by some to indicate the
great lapse of time separating the period of the mammoth
and rhinoceros in England from the modern age. The
scratched boulders in the middle stratum of laminated
clay, would indicate certainly that the material found its
way into the cave during the Glacial epoch, when ice filled
the whole valley of the Ribble, which flows past the foot
of the hill, and whose bed is 900 feet below the mouth of
the cave.

In North Wales the Vale of Clwyd contains numerous
caves which were occupied by hyenas in preglacial times,
and with their bones are associated those of the mammoth,
the rhinoceros, the hippopotamus, the cave lion, the cave
bear, and various other animals. Flint implements also
were found in the cave at Cae Gwyn, near the village of
Tremeirchon, on the eastern side of the valley, opposite
Cefn, and about four miles distant. We have already
given an illustration of the Cefn cave (see page 148). It
will be observed that this valley of the Clwyd opens to the
north, and has a pretty rapid descent to the sea from the
Welsh mountains, and was in position to be obstructed by
the Irish Sea glacier, so as to have been occupicd at times
by one of the characteristic marginal lakes of the Glacial
period. It is evident also that the northern ice prevailed
over the Welsh ice for a considerable portion of the lower
part of the valley; for northern drift is the superficial de-
posit upon the hills on the sides of the valley up to a
height of over 500 feet. From the investigations of Mr.

Ne, MAN AND THE GLACIAL PERIOD.

C. E. De Rance, F. G. 8.,* it is equally clear also that the
northern drift, which until lately sealed up the entrance of
the cave, was subsequent to its occupation by man, and
this was the opinion formed by Sir Archibald Geikie, Di-
rector General of the Geological Survey of the United
Kingdom, as the result of special investigations which he
made of the matter. +

From the caves in the Vale of Clwyd as many as 400
teeth of rhinoceros, 500 of horse, 180 of hyena, and 15 of

mammoth have been taken. A section of the cave deposits -

in the cave at Cae Gwyn is as follows:

“ Below the soil for about eight feet a tolerably stiff

boulder-clay, containing many ice-scratched boulders and
narrow bands and pockets of sand. Below this about
seven feet of gravel and sand, with here and there bands
of red clay, having also many ice-scratched boulders. ‘The
next deposit was a laminated brown clay, and under this
was found the bone-earth, a brown, sandy clay with small
pebbles and with angular fragments of limestone, stalag-
mites, and stalactites. During the excavations it became
clear that the bones had been greatly disturbed by water
action ; that the stalagmite floor, in parts more than a foot
in thickness, and massive stalactites, had also been broken
and thrown about in all positions ; and that these had been
covered afterwards by clays and sand containing foreign
pebbles. ‘This seemed to prove that the caverns, now 400
feet above ordnance datum, must have been submerged
subsequently to their occupation by the animals and by
man. In Dr. Hicks’s opinion, the contents of the cavern
must have been disturbed by marine action during the
great submergence in mid-glacial times, and afterwards

* Proceedings of the Yorkshire Geological Society for 1888, pp-
1-20.

+ See De Rance, as above. p. 17; and article by H. Hicks, in Quar-
terly Journal of Geological Society, vol. xlii, p. 3; Oe Maga-
zine, May, 1885, p. 510.

RELICS OF MAN IN THE GLACIAL PERIOD. 973

covered by marine sands and by an upper boulder-clay,
identical in character with that found at many points in
the Vale of Clwyd. The paleontological evidence sug-
gests that the deposits in question are not preglacial, but
may be equivalent to the Pleistocene deposits of our river-
valleys.” *

If the views of Professor Lewis and Mr. Kendall are
correct concerning the unity of the Glacial period in Eng-
land, the shelly and sandy deposits connected with these
Clwydian caves at an elevation of 400 feet or more would
be explained in connection with the marginal lakes which
must have occupied the valley during both the advance
and the retreat of the ice-front; the shells having been
carried up from the sea-bottom by the ice-movement, after
the manner supposed in the case of those at Macclesfield
and Moel Tryfaen. If, therefore, the statements concern-
ing the discovery of flint implements in this Cae Gwyn
cave can be relied upon, this is the most direct evidence
yet obtained in Europe of man’s occupation of the island
during the continuance of the Glacial period.

In all these caves it is to be noted that there is a sharp
line of demarcation between the strata containing palzo-
lithic implements and those containing only the remains
of modern animals. Paleolithic implements are confined
to the lower strata, which in some of the caves are sepa-
rated from the upper by a continuous bed of stalagmite,
to which reference will be made when discussing the
chronology of the Glacial period. The remains of ex-
tinct animals also are confined to the lower beds.

The caves which we have been considering in England
are all in limestone strata, and have been formed by
streams of water which have enlarged some natural fis-
sures both by mechanical action in wearing away the
rocks, and by chemical action in dissolving them.

* H. B. Woodward’s Geology of England and Wales, pp. 548, 544.

974 MAN AND THE GLACIAL PERIOD.

Through the lowering of the main line of drainage, cay-
erns with a dry floor are at length left, otfering shelter
and protection both to man and beast. Oftentimes, but
not always, some idea of the age of these caverns may be
obtained by observing the depth to which the main chan-
nel of drainage to which they were tributary has been
lowered since their formation. But to this subject also
we will return when we come specifically to discuss the
chronological question. ;

The Continent.

Systematic explorations in the caves of Belgium were
begun in 1833 by Dr. Schmerling, in the valley of the
Meuse, near his residence in Liége. The Meuse is here
bordered by limestone precipices 200 or more feet in
height. Opening out
from these rocky walls
are the entrances to
the numerous caverns
which shave rendered
the region so famous.
To get access to the
most important of
these, Dr. Schmerling
had to let himself
down over a precipice
by a rope tied to a
tree, and then to creep
along on all-fours through intricate channels to reach the
larger chambers which it was his object to explore. In the
cave at Engis, on the left bank of the Meuse, about eight
miles above Liége, he found a human skull deeply buried
in breccia in company with many bones of the extinct ani-
mals previously stated to have been associated with man
during the Glacial period. This so-called “ Engis skull ”
was by no means apelike in its character, but closely re-

EE ~
ZB»

Fie. 79.—Engis skull, reduced (after Lyell.)

RELICS OF MAN IN THE GLACIAL PERIOD. 975

sembled that of the average Caucasian man. But this
established the association upon the Continent of man
with some of the extinct animals of the Glacial period.

The vicinity of Liége has also furnished us another
cavern whose contents are of the highest importance, rank-
ing indeed as perhaps the most significant single discovery
yet made. The cave referred to is on the property of the
Count of Beauffort, in the commune of Spy, in the prov-
ince of Namur in Belgium. For the facts relating to it
we are indebted to Messrs: Lohest and Fraipont, the for-
mer Professor of Geology and the latter of Anatomy in
the University of Liége. The exploration of the cave was
made in 1886, and the full report with illustrations pub-
lished in the following year in Archives de Biologie.*
The significance of this discovery is enhanced by the
light it sheds upon and the confirmation it brings to the
famous Neanderthal skull and others of similar character,
which for a long time had been subjects of vigorous dis-
cussion. Before describing it, therefore, we will give a
brief account of the previous discoveries.

The famous Neanderthal skull was brought to light in
1857 by workmen in a limestone-quarry, near Diisseldorf,
in the valley of the Neander, a small tributary to the
Rhine. By these workmen a cavern was opened upon the
southern side of the winding ravine, about sixty feet above
the stream and one hundred feet below the top of the cliff.
The skull attracted much attention from its supposed pos-
session of many apelike characteristics; indeed, it was
represented by some to be a real intermediate link between
man and the anthropoid apes. The accompanying cut
enables one to compare the outline of the Neanderthal
skull with that of a chimpanzee on the one hand and of
the highly developed European on the other. The ape-
like peculiarities of this skull appear in its vertical depres-

* See pp. 087, 757.

276 MAN AND THE GLACIAL PERIOD.

sion, in the enormous thickness of the bony ridges just
above the eyes, and in the gradual slope of the back part
of the head, together with some other characteristics which
can only be described in technical language ; so that it was
pronounced by the
highest authorities
the most apelike of
human crania which
had yet been discoy-
ered. Unfortunate-
ly, the jaw was not.
found. The capaci-
ty of the skull, how-

Fie. 80.—Comparison of forms of skulls: @, Eu-
ropean; 6, the Neanderthal man; c, a chim- SS
panzee (after Lyell). : EIS) wets seventy

five cubic inches,
which is far above that of the highest of the apes, being
indeed equal to the average capacity of Polynesian and
Hottentot skulls.* Huxley well remarks that “so large a
mass of brain as this would alone suggest that the pithecoid
tendencies indicated by this skull did not extend deep into
the organization.”

Upon extending inquiries, it was found that the Nean-
derthal type of skull is one which still has representatives
in all nations; so that itis unsafe to infer that the individ-
ual was a representative of all the individuals living in his
time. The skull of Bruce, the celebrated Scotch hero,
was a Close reproduction of the Neanderthal type; while,
according to Quatrefages,+ the skull of the Bishop of
Toul in the fourth century “ even exaggerates some of the
most striking features of the Neanderthal cranium. The
forehead is still more receding, the vault more depressed,
and the head so long that the cephalic index is 69-41.”

The discovery of Messrs. Fraipont and Lohest adds

* Huxley’s Man’s Place in Nature, p. 181.
+ Human Species, p. 310.

RELICS OF MAN IN THE GLACIAL PERIOD. 977

much to our definite knowledge of the Neanderthal type of
man, since the Belgic specimens are far more complete than
any others heretofore found, there being in their collection
two skulls, together with the jawbones and most of the
other parts of the frame. In this case also there is no sus-
picion that the deposits had been disturbed, so as to admit

Fie. 81.—Skull of the Man of Spy. (From photograph.)

any intrusion of human relics into the company of relics of
an earlier age. According to M. Lohest, there were three
distinct ossiferous beds, separated by layers of stalagmite.
All the ossiferous beds contained the remains of the
mammoth, but in the upper stratum they were few, and
probably intrusive. The implements found in this were
also of a more modern type. In the second stratum from
the top numerous hearths were found with burnt wood
and ashes, together with the bones of the rhinoceros, the

978 MAN AND THE GLACIAL PERIOD.

horse, the mammoth, the cave-bear, and the cave-hyena,
all of which were abundant, while there were also speci-
mens of the Irish elk, the reindeer, the bison, the cayve-lion,
and several other species. In this layer also there were
numerous implements of ivory, together with ornaments
and some faint indications of carving upon the rib of a
mammoth, besides a few fragments of pottery.

It was in the third, or lowest, of these beds that the
skeletons were found. Here they were associated with
abundant remains of the rhinoceros, the horse, the bison,
the mastodon, the cave-hyena, and a few other extinct
species. Flint implements also, of the “ Mousterien ”
pattern (which, according to the opinion of the French
archeologists, is characteristic of middle paleeolithic times),
were abundant. Neither of the skeletons was com-
plete, but they were sufficiently so to give an adequate
idea of the type to which they belong, and one of the
skulls is nearly perfect. According to M. Fraipont, ‘‘ one
of these skulls is apparently that of an old woman, the
other that of a middle-aged man. ‘They are both very
thick; the former is clearly dolichocephalic (long-headed,
index 70), the other less so. Both have very prominent
eyebrows and large orbits, with low, retreating foreheads,
excessively so in the woman. The lower jaws are heavy.
The older has almost no projecting chin. The teeth are
large, and the last molar is as large as the others. ‘These
points are characteristic of an inferior and the oldest-
known race. The. bones indicate, like those of the Ne-
anderthal and Naulette specimens, small, square-shoul-
dered individuals.” They were “ powerfully built, with
strong, curiously curved thigh-bones, the lower ends of
which are so fashioned that they must have walked with
a bend at the knees.” *

* Huxley, Nineteenth Century, vol. xxviii (November, 1890),
p. 774,

RELICS OF MAN IN THE GLACIAL PERIOD. 979

Other crania from various Quaternary deposits in Eu-
rope seem to warrant the inference that this type of man
was the prevalent one during the early part of the Palzo-
lithic age. As long ago as 1700 a skull of this type was
exhumed in Canstadt, a village in the neighbourhood of
Stuttgart, in Wtrtemberg. This was found in coexist-
ence with the extinct animals whose bones we have de-
scribed as so often appearing in the high-level river-gravel
of the Glacial age. But the importance of the discovery
at Canstadt was not appreciated until about the middle of
the present century. Irom the priority of the discovery,
and of the discussion among German anthropologists con-
cerning it, it has been thought proper, however, by some
to give the name of this village to the race and call it the
“ Canstadt race.” But, whatever name prevails, it is im-
portant in our reading to keep in mind that the man of
Canstadt, the man of Neanderthal, and the man of Spy
are identical in type, and probably in age. Similar dis-
coveries have been made in various other places. Among
these are a lower jaw of the same type discovered in
1865 by M. Dupont, at Naulette, in the valley of the Lesse,
in Belgium, and associated with the remains of extinct
animals; a jawbone found in a grotto at Arcy; a frag-
ment of a skull found in 1865 by Faudel, in the loess of
Eguisheim, near Colmar; a skull at Olmo, discovered in
1863, in a compact clayey deposit forty-five feet below
the surface; and a skull discovered in 1884 at Marcilly.

M. Dupont has brought to ight much additional testi-
mony to glacial man from other caves in different parts of
Belgium. Im all he has explored as many as sixty. Three
of these, in the valley of the Montaigle, situated about
one hundred feet above the river, contained both remains
of man and many bones of the mammoth and other
associated animals, which had evidently been brought in
for food.

In the hilly parts of Germany, also, and in Hungary,

980 MAN AND THE GLACIAL PERIOD.

and even in the Ural Mountains in Russia, and in one of
the provinces of Siberia, the remains of the rhinoceros,
‘and most of the other animals associated with man in
glacial times, have been found in the cave deposits which
have been examined. Though it can net be directly
proved that these animals were associated with man in
any of these places, still it is interesting to see how wide-
spread the animals were in northern Europe and Asia —
during the Glacial period.

Some northern animals, also, spread at this time into
southern Hurope—remains of the reindeer having been ©
discovered on the south slope of the Pyrenees, but the
remains of the mammoth, the woolly rhinoceros, and the
musk ox, have not been found so far south.

African species of the elephant, however, seem at one
time to have had free range throughout Spain, and the
hippopotamus roamed in vast herds over the valleys of
Sicily, while several species of pygmy elephants seem to be
peculiar to the island of Malta.

In the case of all the cave deposits referred to (with
possibly the exception of those of Victoria, England, and
Cae Gwyn, Wales), the evidence of man’s existence dur-
ing the Glacial period is inferential, and consists largely
in the fact that he was associated with various extinct
animals which did not long survive that period, or with
animals that have since retired from Europe to_their
natural habitat in mountain-heights or high latitudes.
The men whose remains are found in the high-level river-
drift, and in the caverns described, were evidently not in
possession of domestic animals, as their bones are con-
spicuous for their absence in all these places. ‘The horse,
which would seem to be an exception, was doubtless used
for food, and not for service.

If we were writing upon the general subject of the
antiquity and development of the human race, we should
speak here in detail of several other caves and rock shel-

RELICS OF MAN IN THE GLACIAL PERIOD. 98]

ters in France and southern Europe, where remains of
man belonging to an earlier period have been found. We
should mention the rock shelter of Cro-Magnon in the
valley of Vezére, as well as that of Mentone, where entire
human skeletons were found. But it is doubtful if these
and other remains from caves which might be mentioned
belong in any proper sense to the Glacial period. The
same remarks should be made also with reference to the
lake-dwellings in Switzerland, of which so much has been
written in late years. All these belong to a much later
age than the river-drift man of whom we are speaking,
and of whom we have such abundant evidence both in
Kurope and in America.

Eatinct Animals associated with Man during the Glacial
Period.

This is the proper place in which to speak more fully

of the extinct animals which accompanied man in his

earliest occupation of Europe and America, and whose

Tene 2), Fig. 83.

Iie. 82.—Tooth of Machairodus neogeus, x 4 (drawn from a cast).

Fie. 83.—Perfect tooth of an Elephas, found in Stanislaus County, California,
2 natural size.

remains are so abundant in the river-drift gravel and in

the caves of England, in connection with the relics of

man. Among these animals are

282 MAN AND THE GLACIAL PERIOD.

The Lion, which is now confined to Africa and the
warmer portions of Asia. But in glacial times a large
species of this genus ranged over Europe from Sicily to
central England.

The saber-toothed TIGER, with tusks ten inches long
(Machairodus latidens), is now extinct. This species was
in existence during the latter part of the Tertiary period,
but continued on until after man’s appearance in the
Glacial period. The presence of this animal would seem
to indicate a warm climate.

The Leoparn (elis pardus) is now confined to Africa
and southern Asia, and the larger islands adjoining ; but
during man’s occupation of Europe in the Glacial epoch
he was evidently haunted at every step by this animal ;
for his bones are found as far north in England as
paleolithic man is known to have ranged.

The HYENA. ‘T'wo species of this animal are found
in the bone-caves of Europe. During the Glacial epoch

Fie. 84.—Skull of Hyena speleea, x 4.

they ranged as far up as northern England, but they are
now limited to Africa and southwestern Asia.

The ELEPHANT is represented in the Preglacial and
Glacial epochs by several species, some of which ranged
as far north as Siberia. The African elephant is not now
found north of the Pyrenees and the Alps. But a species of

¢

RELICS OF MAN IN THE GLACIAL PERIOD. 983

dwarf elephant, but four or five feet in height, has already
been referred to as having occupied Malta and Sicily; and
still another species has been found in Malta, whose aver-
age height was less than three feet. An extinct species
(Llephas antiquus), whose remains are found in the river-
drift and in the lower strata of sediment in many caverns
as far north as Yorkshire, England, was of unusual size,
and during the Glacial period was found on both sides
of the Mediterranean. But the species most frequently
met with in paleolithic times was the mammoth (£/e-
phas primigenus). This animal, now extinct, accom-
panied man in nearly every portion both of Europe and
North America, and lingered far down into post-glacial
times before becoming extinct. This animal was nearly

——

so ORES

Fie. 85.—Celebrated skeleton of mammoth, in St. Petersburg museum.

twice the weight of the modern elephant, and one third
taller. Occasionally his tusks were more than twelve
feet long, and curved upward in acircle. It is the car-
casses of this animal which have been found in the frozen
soil of Siberia and Alaska. It had a thick covering of
long, black hair, with a dense matting of reddish wool at
the roots. During the Glacial period these animals must
have roamed in vast herds over the plains of northern

284 MAN AND THE GLACIAL PERIOD.

France and southern England, and the northern half of

North America.

The HIppopoTAMUS is at present a familiar animal
in the larger rivers of Africa, but is not now found in

Fie. 86.—Molar tooth of mammoth (Elephas primigenius) : a, grinding surface ;
6, side view.

Europe. During the Glacial period, however, he ranged
as far north as Yorkshire, England, and his remains were
found in close association with those of man, both in

Fic. 87.—Tooth of Mastodon
Americanus.

Europe and on the Pacific
coast in America. ‘Twenty
tons of their bones have been
taken from a single cave in
Sicily.*

The mammoth and the
rhinoceros we know to have
been adapted to cold cli-
mates by the possession of
long hair and thick fur, but

the hippopotamus by its love for water would seem to
be precluded from the possession of this protective coy-

* Prestwich’s Geology, vol. ii, p. 508.

RELICS OF MAN IN THE GLACIAL PERIOD. 985

ering. It is suggested, however, by Sir William Daw-
son, that he may have been adapted to arctic climates
by a fatty covering, as the walrus is at the present time.
A difficulty in accounting for many of the remains of
the hippopotamus in some of the English caverns is
that they are so far away from present or possible
water-courses. But it would seem that due credit has
not been ordinarily given to the migratory instincts
of the animal. In southern Africa they are known to
“‘travel speedily for miles over land from one pool of a
dried-up river to another; but it is by water that their
powers of locomotion are surpassingly great, not only in
rivers, but in the sea. ... The geologist, therefore, may
freely speculate on the time when herds of hippopotami
issued from North African rivers, such as the Nile, and
swam northward in summer along the coasts of the Medi-
terranean, or even occasionally visited islands near the
shore. Here and there they may have landed to graze
or browse, tarrying awhile, and afterwards continuing their
course northward. Others may have swum in a few sum-
mer days from rivers in the south of Spain or France to
the Somme, Thames, or Severn, making timely retreat to
the south before the snow and ice set in.” *

The Mastopon (Mastodon Americanus), (Fig. 88),
“is probably the largest land mammal known, unless we
except the Dinotheriwm. It was twelve to thirteen feet
high, and, including the tusks, twenty-four to twenty-five
feet long. It differed from the elephant chiefly in the
character of its teeth. The difference is seen in Figs. 86
and 87. The elephant’s tooth given above (Fig. 86) is
sixteen inches long, and the grinding surface eight inches
by four.”

The mastodon, together with the mammoth, made
their appearance about the middle of the Miocene epoch.

5 * Lyell, Antiquity of Man, p. 180,

286 MAN AND THE GLACIAL PERIOD.

At the close of the Tertiary period the mastodon became
extinct on the Eastern Continent, but continued in North
America to be a companion of man well on toward the-
close of the Glacial period. Many perfect skeletons have

Fig. 88.—Mastodon Americanus (after Owen).

been found in the deposits of this period in North Amer-
ica. “One magnificent specimen was found in a marsh
near Newburg, New York, with its legs bent under the
body, and the head thrown up, evidently in the very posi-
tion in which it mired. The teeth were still filled with
the half-chewed remnants of its food, which consisted of
twigs of spruce, fir, and other trees; and within the ribs,
in the place where the stomach had been, a large quantity
of similar material was found.” *

The RHINOCEROS is now confined to Africa and south-

* Le Conte’s Geology (edition of 1891), p. 582.

RELICS OF MAN IN THE GLACIAL PERIOD. 987

ern Asia; but the remains of four species have been found
in America, Europe, and northern Asia, in deposits of
the Glacial period. In company with that of the mam-
moth, already spoken of, a carcass of the woolly rhinoceros
was. found in 1771 im the
frozen soil of northern S$i-
beria. The bones of other
species have been found as
far north as Yorkshire, Eng-
land. In the valley of the
Somme there was found “the Fi. 89.—Skeleton of Rhinoceros
tichorhinus.

whole hind limb of a rhinoce-

ros, the bones of which were still in their true relative po-
sition. ‘They must have been joined together by ligaments
and even surrounded by muscles at the time of their inter-
ment.” An entire skeleton was found near by. The gravel
terrace in which these occurred is about forty feet above
the floor of the valley, and must have been formed subse-

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quent to some of the strata which contained the remains
of human art. In America the bones are found in the
gold-bearing gravels of California, in connection with hu-
man remains.

The BEAR was represented in Europe in paleolithic
times by three species, of which only one exists there at

988 MAN AND THE GLACIAL PERIOD.

the present time. But during the Glacial period the
grizzly bear, now confined to the western part of America,
and the extinct cave-bear were companions, or enemies as
the case may be, of man throughout Europe. The cave-bear
was of large size, and his bones occur almost everywhere
in the lower strata of sediment in the caves of England.
The great Irish ELK, or deer, is now extinct, though
it 1s supposed by some to
va S\ S have lingered until his-
| : : v toric times. Its remains ©
ZS are found widely distrib-
uted over middle Europe
in deposits of paleeolithic
age. |
The Horse was also,
as we have seen, a very
constant associate of man
in middle Europe during
the Paleolithic age, but
probably not as a domes-
ticated animal. The evi-
dence is pretty conclusive
that he was prized chiefly for food. About some of the
caves in France such immense quantities of their bones
are found that they can be accounted for best as refuse-
heaps into which the useless bones had been thrown
after their feasts, after the manner of the disposal of
shells of shell-fish. In America the horses associated
with man were probably of a species now extinct. ‘The
skull of one (Hquus excelsus) recently found in Texas,
in Pleistocene deposits, associated with human imple-
ments, is, according to Cope, intermediate in character
between the horse and quagga.* The frontal bone was
crushed in in a manner to suggest that it had been knocked

UT
GIN
(

Fig.91 .—Skeleton of the Irish elk (Cervus
megaceros).

—___

* American Naturalist, vol. xxv (October, 1891), p. 912.

RELICS OF MAN IN THE GLACIAL PERIOD. 989

in the head with a stone hammer, such as was found in

the same bed. Possibly, therefore, man’s love of horse-

flesh may have been an important element in securing the
* extinction of the species in America.

Besides these animals there were associated with man
at this time the Musk SHEEP and the REINDEER, both
now confined to the regions of the far north, but dur-
ing the Glacial period ranging into southern France, and
mingling their bones with those both of man and of the
southern species already enumerated.

The WOLVERINE, the Arotic Fox, the Marmot, the
LEeMMING—all now confined to colder regions—at that
time mingled on the plains of central Europe with the
species mentioned as belonging now to Africa and south-

Fic. 92.—Musk-sheep (Ovibos moschatius).

ern Asia. The IBEX, also,and the SNowy VOLE and CHA-
MOIS descended to the plains from their mountain-heights,
and joined in the strange companionship of animals from
the north and from the south.

Besides these extremes there were associated with man
during the Glacial period numerous representatives of the
temperate group of existing animals, such as the bison,
the horse, the stag, the beaver, the hare, the rabbit, the

290 MAN AND THE GLACIAL PERIOD.

otter, the weasel, the wild-cat, the fox, me wolf, the wild
boar, and the brown bear.

To account for this strange intermingling of arctic and
torrid species of animals, especially in Europe, during man’s
occupancy of the region in glacial times, various theories
have been resorted to, but none of them can be said to be
altogether satisfactory. One hypothesis is that the bones

of these diverse animals

cS FZ became mingled by reason
UG PAL of the great range of the

Z " 2 R annual migration of the
(C i sh Sag z species. The reindeer, for
f ey , example, still performs ex-

1“« tensive annual migrations.
my: In summer it ventures far

+ ==) Sf

out upon the tundras of
Fie. 93.—Reindeer.

North America and Siberia
to feed upon the abundant vegetation that springs up like
magic under the influence of the long days of sunshine;
while, as winter approaches, it returns to the forests of the
interior. Orin other places this animal and his associates,
like birds of passage, move northward in summer to escape
the heat, and southward in the winter to escape the ex-
treme cold. Many of the other animals also are more or
less migratory in their habits.

Thusit is thought that during the Glacial period, when
man occupied northern France and southern England,
the reindeer, the musk sheep, the arctic fox, and perhaps
the hippopotamus and some other animals, annually
vibrated between northern England and southern France,
a slight elevation of the region furnishing a land passage
from England to the continent; while the chamois and
other Alpine species vibrated as regularly between the val-
leys in winter and the mountain-heights insummer. The
habits of these species are such that it is not difficult to see
how in their case this migration could have taken place.

RELICS OF MAN IN THE GLACIAL PERIOD. 99]

Professor Boyd Dawkins attempts to reduce the diffi-
culty by supposing that the Glacial epoch was marked by
the occurrence of minor periods of climatic variation, dur-
ing which, in comparatively short periods, the isothermal
lines vibrated from north to south, and wice versa. In this
view the southern species gradually crowded upon the
northern during the periods of climatic amelioration,
until they reached their limit in central England, and
then in turn, as the climate became more rigorous, slowly
retreated before the pressure of their northern competitors.
Meanwhile the hyena sallied forth from his various caves,
over this region, at one time of the year to feed upon the
reindeer, and at another time of the year upon the flesh
of the hippopotamus, in both cases dragging their bones
with him to his sheltered retreat in the limestone caverns *
which he shared at intervals with paleolithic man.

The theory of Mr. James Geikie is that the period,
while one of great precipitation, was characterised by a
climate of comparatively even temperature, in which there
was not so great a difference as now between the winters
and the summers, the winters not being so cold and the
summers not so hot as at present. This is substantially
the condition of things in southern Alaska at the present
time, where extensive glaciers come down to the sea-level,
even though the thermometer at Sitka rarely goes below
zero (Fahrenheit). It is, therefore, easy to conceive that
if there were extensive plains bordering the Alaskan archi-
pelago, so as to furnish ranging grounds for more south-
ern species, the animals of the north and the animals of
the south might partially occupy the same belt of terri-
tory, and their bones become mingled in the same river
deposits. —

In order to clear the way for either of these hypotheses
to account for the mingling of arctic and torrid species

* Harly Man in Britain, p. 114.

299, MAN AND THE GLACIAL PERIOD.

characteristic of the period under consideration in Europe,
we must probably suppose such an elevation of the region
to the south as to afford land connection between Europe
and Africa. This would be furnished by only a moderate
amount of elevation across the Strait of Gibraltar and
from the south of Italy to the opposite shore in Africa;
and there are many indications, in the distribution of
species, of the existence in late geological times of such
‘connection.

It should also be observed that the present capacities
and habits of species are not a certain criterion of their
past habits and capacities. As already remarked, both the
rhinoceros and the mammoth of glacial times were prob-
ably furnished with a woolly protection, which enabled
them to endure more cold than their present descendants
could do, while the elephant is even now known to be able
to endure the rigors of the climate at great elevations upon
the Himalaya Mountains. We can easily imagine these
species to have been adjusted to quite different climatic
conditions from those which now seem necessary to their
existence. In the case of the hippopotamus, also, it is
quite possible, as already suggested, that it 1s more inclined
to migration than is generally supposed. |

Geikie’s theory of the prevalence of an equable climate
during a portion of the Glacial period in Europe 1s
thought to be further sustained by the character of the
vegetation which then covered the region, as well as by
the remains of the mollusks which occupied the waters.
Then “temperate and southern species like the ash, the
poplar, the sycamore, the fig-tree, the Judas-tree, the
laurel, etc., overspread all the low ground of France, as
far north at least as Paris. . . . It was under such condi-
tions,” continues Geikie, “that the elephants, rhinoceroses,
and hippopotamuses, and the vast herds of temperate
cervine and bovine species ranged over Europe, from the
shores of the Mediterranean up to the latitude of York-

RELICS OF MAN IN THE GLACIAL PERIOD. 993

shire, and probably even farther north still; and from the
borders of Asia to the Western Ocean. Despite the pres-
ence of numerous fierce carnivora—lions, hyenas, tigers,
and others—LEurope at that time, with its shady forests,
its laurel-margined streams, its broad and deep-flowing
rivers, a country in every way suited to the needs of a
race of hunters and fishers—must have been no unpleas-
ant habitation for paleeolithic man.

“ This, however, is only one side of the picture. There
was a time when the climate of Pleistocene Europe pre-
sented the strongest contrast to those genial conditions—
a time when the dwarf birch of the Scottish Highlands,
and the arctic willow, with their northern congeners, grew
upon the low grounds of middle Europe. Arctic animals,
such as the musk sheep and the reindeer, lived then, all
the year round, in the south of France; the mammoth
ranged into Spain and Italy; the glutton descended to
the shores of the Mediterranean ; the marmot came down
to the low grounds at the foot of the Apennines; and the
lagomys inhabited the low-lying maritime districts of
Corsica and Sardinia. The land and fresh water shells of
many Pleistocene deposits tell a similar tale; boreal, high
alpine, and hyperborean forms are characteristic of these
accumulations in central Europe; even in the southern
regions of our continent the shells testify to a former
colder and wetter climate.” *

In Mr. Geikie’s view these facts indicate two Glacial
periods, with an intervening epoch of mild climate. In
the opinion of others they are readily explainable by the
coming on and departure of a single Ice age, with its vari-
ous minor episodes.

* Prehistoric Europe, p. 67.

994 MAN AND THE GLACIAL PERIOD.

Earliest Remains of Man on the Pacific Coast of North

America.

Most interesting evidence concerning the antiquity of
man in America, and his relation to the Glacial period,
has come from the Pacific coast. During the height of
the mining activity in California, from 1850 to 1860,

numerous reports were rife that human remains had been ~

discovered in the gold-bearing gravel upon the flanks of
the Sierra Nevada Mountains. These reports did not

attract much scientific attention until they came to relate -

to the gravel deposits found deeply buried beneath a flow

---e--L

<r

Fig. 94.—Section across Table Mountain, Tnolumne County, California: JZ,
lava; G, gravel; S, slate; R&, old river-bed ; #’, present river-bed.

jimaca = Ty ({| ae

in ENN | Ml i AMM li ain

il
|

of lava locally known as the Sonora or Tuolumne Table
Mountain. This lava issued from a vent near the summit
of the mountain-range, and flowed down the valley of the
Stanislaus River for a distance of fifty or sixty miles,
burying everything in the valley beneath it, and compel-
ling the river to seek another channel. The thickness of
the lava averages about one hundred feet, and so long a
time has elapsed since the eruption that the softer strata
on either side of the valley down which it flowed have
been worn away to such an extent that the lava now rises
nearly everywhere above the general level, and has become
a striking feature in the landscape, stretching for many
miles as a flat-topped ridge about half a mile in width,
and presenting upon the sides a perpendicular face of
solid basalt for a considerable distance near the lower end
of the flow.

RELICS OF MAN IN THE GLACIAL PERIOD. 995

It was under this mountain of lava that the numerous
implements and remains of man occurred which were
reported to Professor J. D. Whitney when he was con-
ducting the geological survey of California between 1860

(From Whitney.)

Fic. 95.—Calaveras Skull.

and 1870. The implements consisted of stone mortars
and pestles, suitable for use in grinding acorns and other
coarse articles of food. ‘There were, however, some rude
articles of ornament. In one of the mining shafts pene-

296 MAN AND THE GLACIAL PERIOD.

trating the gravel underneath Table Mountain, near
Sonora, there was reported to have been discovered, in
1857, a human jawbone, one portion of which was sent by
responsible parties to the Boston Society of Natural His-
tory, and another part to the Philadelphia Academy of
Sciences, in whose collections the fragments can now be
seen.

Interest reached a still higher pitch when, in 1866, an ©

entire human skull with some other human bones was
reported to have been discovered under this same lava

deposit, afew miles from Sonora, at Altaville, in Calaveras

County, and hence known as the “ Calaveras skull.” Per-
sistent efforts were made soon after to discredit the
genuineness of this discovery. Bret Harte showered upon
it the shafts of his ridicule, and various other persons gave
currency to the story that the whole report originated in
a joke played by the miners upon unsuspecting geologists.
These attacks were so successful that many conservative
archeologists and men of science have refused to accept
the skull as genuine.

Recent events, however, have brought such additional
evidence * to the support of this discovery that it would
seem unreasonable any longer to refuse to credit the testi-
mony. At the meeting of the Geological Society of
America, at Washington, in January, 1891, Mr. George F.
Becker, of the United States Geological Survey, who for
some years has had charge of investigations relating to
the gold-bearing gravels of the Pacific coast, presented
the affidavit of Mr. J. H. Neale, a well-known mining
engineer of unquestionable character, stating that he had
taken a stone mortar and pestle, together with some spear-
heads (which through Mr. Becker he presented to the
Society), from undisturbed strata of gravel underneath
the lava of Table Mountain, near Rawhide Gulch, a few

* See Bulletin Geological Society of America, 1891, pp. 189-200.

RELICS OF MAN IN THE GLACIAL PERIOD. 9297

miles from Sonora. At the same meeting Mr. Becker
presented a pestle which Mr. Clarence King, the first
director of the United States Geological Survey, took with
his own hands out of undisturbed gravel under this same
lava deposit, near Tuttletown, a mile or two from the pre-
ceding locality mentioned.

I was so fortunate, also, as to be able to report to
the Society at the same meeting the discovery, in 1887,
of a small stone mortar by Mr. C. McTarnahan, the as-
sistant surveyor of Tuolumne County. This mortar was
found by Mr. McTarnahan in the Empire mine, which
penetrates the gravel underneath Table Mountain, about
three miles from Sonora, and not far from the other locali-
ties above mentioned. ‘The place where the mortar was
found is about one hundred and seventy-five feet in from
the edge of the superincumbent lava, which is here about
one hundred feet in thickness. At my request, this mor-
tar was presented by its owner, Mrs. M. J. Darwin, to the
Western Reserve Historical Society of Cleveland, Ohio,
in whose collection it can now be seen.

These three independent instances, each of them au-
thenticated by the best of evidence, have such cumulative
force that probably few men of science will longer stand
out against it.

Associated with these discoveries, there is to be men-
tioned another, which was brought to my notice by Mr.
Charles Francis Adams in October, 1889.+ This was a
miniature clay image of a female form, about one inch
and a half in length, and beautifully formed, which was
found, in August, 1889, by Mr. M. A. Kurtz, while boring
an artesian well at Nampa, Ada County, Idaho. ‘The
strata passed through included, near the surface, fifteen
feet of lava. Underneath this, alternating beds of clay and

+ See Proceedings Boston Society Natural History, January, 1890,
and February, 1591.

298 MAN AND THE GLACIAL PERIOD.

quicksand occurred to a depth of three hundred and
twenty feet, where there appeared indications of a former
surface soil lying just above the bed-rock, from which
the clay image was brought up in the sand-pump.

Fic. 96.—Three views of Nampa image drawn to scale. The middle one is from
a photograph.

I devoted the summer of 1890 to a careful study of
the lava deposits both in Idaho and in California, with a
view to learning their significance with reference to these
discoveries. The main facts brought to light by this
investigation are that in the Snake River Valley, Idaho,
there are not far from twelve theusand square miles of
territory covered with a continuous stratum of basaltic
lava, extending nearly across the entire diameter of the
State from east to west. Nampa, where the miniature
image was discovered, is within five miles of the western
limit of this lava-flow, and where it had greatly thinned
out. The relative age of the lava is shown by its relation
to Tertiary beds of shale and sandstone, containing numer-
ous fossils of late Pliocene species. These are overlaid in
this vicinity by the lava, thus determining its post-'Ter-
tiary character. Examination with reference to the more
precise determination of age reveals channels of erosion
formed since the lava-flow took place, which, when studied
sufficiently, will probably lead to valuable approximate

RELICS OF MAN IN THE GLACIAL PERIOD. 999

results. At present I can only say that the amount of
erosion since the lava eruptions of western Idaho is not
excessive, and very likely may be brought within a period
of from ten thousand to twenty thousand years. ‘The
enormous erosion in the cafion of the Snake River, near
Shoshone Falls, in central Idaho, is doubtless of a much
earlier date than that in the Boisé River, near Nampa.
The disturbances created in this part of the valley by
the bursting of the barriers between the glacial Lake

Salmon City

D

oe

ASS)
vA Coes oKetéhum
HoIse di ‘ ~
o 2. 7RO NY ba Hailey

Fic. 97.—Map showing Pocatello, Nampa, and the valley of Snake River.

Bonneville and the Snake River, already described (see
above, page 233), have not been worked out. There can
be no doubt, however, that interesting results will come
to light in connection with the problem; for Pocatello,
the point at which the débdcle reached the Snake River
plain, is about 2,000 feet higher than Nampa, and 350
miles distant, and the water must have poured into the
valley faster than the river in its upper portion could have
discharged it. By just what channels the mighty current
worked down to the lower levels on the western borders
of the State it would be most interesting as well as in-
structive to know.

A study of the situation in Tuolumne and Calaveras

300 MAN AND THE GLACIAL PERIOD.

Counties, California, reveals a state of things closely re-
sembling, in important respects, that in western Idaho.
At first sight the impression is made that an immense
lapse of time must have occurred since the volcanic erup-
tion which furnished the lava of Table Mountain. The
Stanislaus River flows in a channel of erosion a thousand
feet or more lower than the ancient channel filled by lava,
and in two or three places cuts directly across it. An
immense amount of time, also, would seem to be required
to permit the smaller local streams to have worn away so

Fig. 98.—Section along the line, north and south: 7’ 7’, old river-beds; 7 7,
present river-beds ; Z, lava; si, slate.

much of the sides of the ancient valley as to allow the
lava deposit now so continuously to rise above the general
surface. Still, the question of absolute time cannot be
considered separately without much further study. It is
by no means certain that, when the lava-stream poured
down the mountain, it always followed the lowest depres-

sions; but at certain points it may have been dammed

up In its course by its own accumulations so as to be turned
off into what was then an ancient abandoned channel.
The forms of animal and vegetable life with which
the remains of man under Table Mountain are associated,
are, indeed, to a considerable extent, species now extinct
in California, and some of them no longer exist anywhere
in the world. But a suggestion of Professor Prestwich,
in England, made with reference to the extinct forms of
life associated with human remains in the glacial deposits
in Kurope, is revived by Mr. Becker, of the Geological
Survey, with reference to the California discoveries; his

RELICS OF MAN IN THE GLACIAL PERIOD. 301

inference being, not that man is so extremely ancient in
California, but that many of these plants and animals
have continued to a more recent date than has ordinarily
been supposed.

The connection of these lava-flows on the Pacific coast

with the Glacial period is unquestionably close. For
some reason which we do not fully understand, the vast
accumulation of ice in North America during the Glacial
period is correlated with enormous eruptions of lava west
of the Rocky Mountains, and, in connection with these
events, there took place on the Pacific coast an almost
entire change in the plants and animals occupying the
region. Mr. Warren Upham is of the opinion that on
the Pacific coast they lingered much later than in the
region east of the Rocky Mountains. Indeed, it is pretty
certain that not many centuries have elapsed since the
glacial phenomena of the Sierra Nevada Mountains were
much more pronounced than they are at the present time,
and it is equally certain that there have been vast erup-
tions of lava in California within three hundred years.
_ From these data, therefore, Mr. Becker has real foun-
dation for his suggestion that perhaps in the Glacial
period California was a kind of health resort for Pliocene
animals, as it is at the present time for man; or, at any
rate, that the later date of the accumulations permitted
the animals to survive there much longer than in the re-
gion east of the Rocky Mountains.

Further discussion of the preceding facts will profit-
ably be deferred until, in the next two chapters, the ques-
tions of the cause and date of the Glacial period have
been considered.

CEA AGH PeXe

THE CAUSE OF THE GLACIAL PERIOD.

In searching for the cause of the Glacial period, it is
evident that we must endeavor to find conditions which
will secure over the centre of the glaciated area either a
great increase of snow-fall or a great decrease in the mean
annual temperature, or both of these conditions combined
in greater or less degree. As can be seen, both from the
nature of the case and from the unglaciated condition of
Siberia and northern Alaska, a low degree of temperature
is not sufficient to produce permanent ice-fields. If the
snow-fall is excessively meagre, even the small amount of
heat in an arctic summer will be sufficient to melt it all
away. |

From the condition of Greenland, however, it appears
that a moderate amount of precipitation where it is chiefly
in the form of snow may produce enormous glaciers if at
the same time the average temperature is low. In south-
eastern Alaska, on the other hand, the glaciers are of enor-
mous size, though the mean annual temperature is by no
means low, for there the great amount of snow-fall amply
compensates for the higher temperature.

Snow stores the cold and keeps it in-a definite place.
If the air becomes chilled, circulation at once sets in, and
the cold air is transferred to warmer regions; but if there
is moisture in the air, so that snow forms, the cold becomes
locked up, as it were, and falls to the earth.

The amount of cold thus locked up in snow is enor-

THE CAUSE OF THE GLACIAL PERIOD. 303

mous. To melt one cubic foot of ice requires as much heat
as would raise the temperature of a cubic foot of water
176° Fahrenheit. To melt a “layer of ice only one inch
and ahalf thick would require as much heat as would raise
a stratum of air eight hundred feet thick from the freez-
ing-point to the tropical heat of 88° Fahrenheit.” It is
the slowness with which ice melts which enables it to
accumulate as it does, both in winter and upon high
mountains and in arctic regions. Captain Scoresby re-
lates that when near the north pole the sun would some-
times be so hot as to melt the pitch on the south side of
his vessel, while water was freezing on the north side, in
the shade, owing to the cooling effect of the masses of ice
with which he was surrounded.

Thus it will appear that a change in the direction of
the moist winds blowing from the equator towards the
poles might produce a Glacial epoch. If snow falls upon
the ocean it cools the water, but through the currents,
everywhere visible in the sea, the temperature in the water
in the different parts soon becomes equalized. If, how-
ever, the snow falls upon the land, it must be melted by
the direct action of the sun and wind upon the spot where
itis. Ifthe heat furnished by these agencies is not suffi-
cient to do it year by year, there will soon be such an
accumulation that glaciers will begin to form. It is clear,
therefore, that the conditions producing a Glacial period
are likely to prove very complicated, and we need not be
surprised if the conclusions to which we come are incapable
of demonstration.

Theories respecting the cause of the Glacial period
may be roughly classified as astronomical and geological.
Among the astronomical theories, one which has some-
times been adduced is that the solar system in its move-
ment through space is subjected to different degrees of
heat at different times. According to this theory, the
temperate climate which characterised the polar regions

804 MAN AND THE GLACIAL PERIOD.

during the Tertiary period, and continued up to the be-
ginning of the Glacial epoch, was produced by the influ-
ence of the warmer stretches of space through which the
whole solar system was moving at that time; while the
Glacial period resulted from the influence upon the earth
of the colder spaces through which the system subsequently
moved.

While it is impossible absolutely to disprove this

hypothesis, it labors under the difficulty of having little

positive evidence in its favor, and thus contravenes a

fundamental law of scientific reasoning, that we must have
areal cause upon which to rest our theories. In endeay-
ouring to explain the unknown, we should have something
known to start with. But in this case we are not sure
that there are any such variations in the temperature of
the space through which the solar system moves. ‘This
theory, therefore, cannot come in for serious considera-
tion until all others have been absolutely disproved. As
we shall also more fully sce, in the subsequent discussion,
the distribution of the ice during the Glacial period was
not such as to indicate a gradual extension of it from the
north pole, but rather the accumulation upon centres many
degrees to the south.

Closely allied with the preceding theory is the sup-
position broached by some astronomers that the sun is a
variable star, dependent to some extent for its heat upon
the impact of meteorites, or to the varying rapidity with
which the contraction of 1ts volume is proceeding.

It is well known that when: two solid bodies clash to-
gether, heat is produced proportionate to the momentum
of the two bodies. In other words, the motion which is
arrested is transformed into heat. Mr. Croll, in his last
publication * upon the subject, ingeniously attempted to
account for the gaseous condition of the nebule and the

* Stellar Evolution and its Relation to Geological Time.

THE CAUSE OF THE GLACIAL PERIOD. 303

heat of the sun and other fixed stars by supposing it to be
simply transformed motion. According to this theory,
the original form of force imparted to the universe was
that exerted in setting in motion innumerable dark bodies,
which from time to time have collided with each other.
The effects of such collisions would be to transform a large
amount of motion into heat and its accompanying forms
of molecular force. The violence of the compact of two
worlds would be so great as to break them up into the
original atoms of which they are composed, and the heat set
free would be sufficient to keep the masses in a gaseous con-
dition and cause them to swell out into enormous propor-
tions. From that time on, as the heat radiated into space,
there would be the gradual contraction which we sup-
pose is going on in all the central suns, accompanied, of
course, with a gradual decline of the heat-energy in the
system.

Now, it is well known that the earth and the solar
system in their onward progress pass through trains of
meteorites. The tails of some of the comets are indeed
pretty clearly proved to be streams of ponderable matter,
through which, from time to time, the minor members of
the solar system plunge, and receive some accession to
their bulk and weight. The shooting-stars, which occa-
sionally attract our attention in the sky, mark the course
of such meteorites as they pass through the earth’s atmos-
phere, and are heated to a glow by the friction with it.
It has been suggested, therefore, that thesun itself may at
times have its amount of heat sensibly affected by such
showers of meteorites or asteroids. Upon this theory the
warm period of the Tertiary epoch, for instance, may
have been due to the heat temporarily added to the sun
by impact with minor astronomical bodies. When, after-
wards, it gradually cooled down, receiving through a long
period no more accessions of heat from that source, the
way was prepared for the colder epoch of the Glacial

306 MAN AND THE GLACIAL PERIOD.

period, which, in turn, was dispelled by fresh showers of
meteorites upon the sun, sufficient to produce the amelio-
ration of climate which we experience at the present time.

As intimated, this theory is closely allied to the pre-
ceding, the principal difference being that it limits the
effects of the supposed cause to the solar system, and looks
to our sun as the varying source of heat-supply. It has
the advantage over that, however, of possessing a more
tangible vera causa. Meteorites, asteroids, and comets

are known to be within this system, and have occasional

collisions with other members of it. But tie principal
objection urged against the preceding theory applies here,
also, with equal force. The accumulations of ice during
the Glacial period were not determined by latitude. In
North America the centre of accumulation was south of
the Arctic Circle—a fact which points clearly enough to
some other cause than that of a general lowering of the
temperature exterior to the earth.

The same objections would bear against the theory
ably set forth by Mr. Sereno EK. Bishop, of Honolulu,
which, in substance, is that there may be considerable
variability in the sun’s emission of heat, owing to fluctua-
tions in the rate of the shrinkage of its diameter, brought
about by the unequal struggle between the diminishing
amount of heat in the interior and the increasing force of
the gravitation of its particles, and by the changes in the
enveloping atmosphere of the sun, which, like an enswath-
ing blanket, arrests a large portion of the radiant heat
from the nucleus, and is itself evidently subject to vio-
lent movements, some of which seem to carry it down to
the sun’s interior. Unknown electrical forces, he thinks,
may also combine to add an element of variability. These
supposed changes may be compared to those which take
place upon the surface of the earth when, at irregular
intervals, immense sheets of lava, like those upon the
Pacific coast of North America, are exuded In a compara-

THE CAUSE OF THE GLACIAL PERIOD. 307

tively brief time, to be succeeded by a long period of rest.
The heat thus brought to the surface of the earth would
add perceptibly to that radiated from it into space in or-
dinary times. Something similar to this upon the sun, it
is thought, might produce effects perceptible upon the
earth, and account for alternate periods of heat and
cold.

A fourth astronomical theory is that there has been a
shifting of the earth’s axis; that at the time of the Gla-
cial period the north pole, instead of being where it now
is, was somewhere in the region of central Greenland.
This attractive theory has been thought worthy of atten-
tion by President T. C. Chamberlin and by Professor G.
C. Comstock,* but it likewise labours under a twofold
difficulty: First, the shifting of the poles observed (450
feet per year) is too slight to have produced the changes
within any reasonable time, and it is not likely to have
been continuous for along period. But still more fatal
to the theory is the fact that the warm climate preceding
the Glacial period seems to have extended towards the
present north pole upon every side; a temperate flora
having been found in the fossil plants of the Tertiary beds
in Greenland and northern British America, as well as
upon Nova Zembla and Spitzbergen.

A fifth astronomical theory, and one which has of late
years been received with great favour, is that so ably ad-
vocated by the late Dr. James Croll and by Professor James
Geikie. Following the suggestions of the astronomer
Adhemar, these writers have attempted to show that not
only one Glacial epoch, but a succession of such epochs,
has been produced in the world by the effect of the
changes which are known to have taken place in the

* See papers by these gentlemen read at the meeting of the Ameri-
ean Association for the Advancement of Science, in Washington, in
August, 1891. Professor Comstock’s paper appeared in the American
Journal of Science for January, 1892.

308 MAN AND THE GLACIAL PERIOD.

eccentricity of the earth’s orbit when combined with the
precession of the equinoxes—another calculable astro-
nomical cause.

It is well known that the earth’s orbit is elliptical ; that

is, it is longer in one direction than in the other, so that

the sun is one side of the centre. During the winter of
the northern hemisphere the earth is now about three

A

7 N.P.

SUMMER \ ae

S.P.¢

N.P.

Wy
O= E

w=
ZS

WINTER SUMMER

Fia. 99.—Diagram showing effect of precession: A. condition of things now ;
B, as it will be 10,500 years hence. ‘The eccentricity is of course greatly ex-
aggerated.

million miles nearer the sun than in the summer; but
the summer makes up for this distance by being about
seven days longer than the winter. Through the preces-
sion of the equinoxes this state of things will be reversed
in ten thousand five hundred years; at which time we
shall be nearer the sun during our northern summer, and
farther away in winter, our winter then being also longer
than our summer. Besides, through the unequal at-
traction of the planets the eccentricity of the earth’s
orbit periodically increases and diminishes, so that there
have been periods when the earth was ten million five

THE CAUSE OF THE GLACIAL PERIOD. 309

hundred thousand miles farther from the sun in winter
than in summer; at which times, also, the winter was
nearly twenty-eight days longer than the summer. Such
an extreme elongation of the earth’s orbit occurred about
two hundred and fifty thousand years ago.

It is easy to assume that such a change in astronomical
conditions would produce great effects upon the earth’s
climate ; and equally easy to connect with those effects the
vast extension of ice during the Glacial period. Since,
also, this period of extreme eccentricity terminated only
eighty thousand years ago, the close of the Glacial period
would, perhaps, upon Mr. Croll’s theory, be comparatively
a recent event; for if the secular summer of the earth’s
eccentricity lags relatively as far behin« the secular move-
ments as the annual summer does behind the vernal
equinox, we should, as Professor Charles H. Hitchcock
suggests, have to place the complete breaking up of the
Ice period as late as forty thousand years ago.*

We have no space to indicate, as it deserves, the com-
parative merits and demerits of this ingenious theory. It
would, however, be a great calamity to have geologists
accept it without scrutiny. It is, indeed, a part of the
business of geologists to doubt such theories until they
are verified by a thorough examination of all accessible
terrestrial evidence bearing upon the subject. There is no
reason to question the reality of the variations in the rela-
tive positions of the earth and the sun assumed by Mr.
Croll; though there may be serious doubt whether the
effects of those changes upon climate would be all that is
surmised, since equal amounts of heat would fall upon
the earth during summer, whether made longer or shorter
by the cause referred to. During the short summers
the earth is.so much nearer the sun that it receives
each season absolutely as much heat as it does during the

* Geology of New Hampshire, vol. in, p. 327.

310 MAN AND THE GLACIAL PERIOD.

longer summers, when it is so much farther away from
the sun. Thus the theory rests at last upon the question
what would become of the heat reaching the earth in
these differing conditions. It is plausibly urged by Mr.
Croll that when a hemisphere of the earth is passing
through a period of long winters the radiation of heat will
be so excessive that the temperature would fall much
below what it would during the shorter winters; and
so ice and snow would accumulate far beyond the usual

amount. It is also supposed that the effect of the sum-—

mer’s sun in melting the ice during the short summer
would be diminished through natural increase of the
amount of foggy and cloudy weather.

Adhémar’s theory is supposed by Sir Robert Ball,
Royal Astronomer of Ireland, te be considerably re-enforced
by a discovery which he has made concerning the dis-
tribution of heat upon the earth during the seasons cul-
minating in the summer and winter solstices. Croll had
assumed, on the authority of Herschel, that a hemisphere
of the earth during the longer winter in aphelion would
receive the same actual amount of heat which would fall
upon it during the shorter summer in perihelion; whereas,
according to Dr. Ball’s discovery, “of the total amount of
heat received from the sun on a hemisphere of the earth
in the course of a year, sixty-three per cent is received dur-
ing the summer and thirty-seven per cent during the win-
ter.’* When, therefore, the summers occur in perihelion
the heat is more intense than Croll had supposed, and,
at the same time, the winters occurring in aphelion
are more deficient in heat than he had assumed. .This
discovery of Dr. Ball will not, however, materially affect
the discussion of Croll’s theory upon its inherent mer-
its, since it is simply an intensification of the causes
invoked by him. We will therefore let it stand or fall

—w

* Cause of an Ice Age, p. 90.

THE CAUSE OF THE GLACIAL PERIOD. Sal

in the light of the general considerations hereafter to be
adduced.

The aid of theoretical consequent changes in the vol-
ume of the Gulf Stream, and in the area of the trade-
winds, has also to be invoked by Mr. Croll. The theory
likewise receives supposed confirmation from facts alleged
concerning the present climate of the southern hemisphere
which is passing through the astronomical conditions
thought to be favourable to its glaciation. ‘The antarctic
continent is completely enveloped in ice, even down to
the sixty-seventh degree of latitude. A few degrees nearer
the pole Sir J. C. Ross describes the ice as rising from
the water in a precipitous wall one hundred and eighty
feet high. In front of such a wall, and nearly twenty
degrees from the south pole, this navigator sailed four
hundred and fifty miles! Voyagers, in general, are said
to agree that the summers of the antarctic zone are
much more foggy and cold than they are in corresponding
latitudes in the northern hemisphere; and this, even
though the sun is 3,000,000 miles nearer the earth during
the southern summer than it is during the northern.

Another direction from which evidence is invoked in
confirmation of Mr. Croll’s theory is the geological indi-
cations of successive Glacial epochs in times past. If
there be a recurring astronomical cause sufficient of itself
to produce Glacial periods, such periods should recur as
often as the cause exists; but glaciation upon the scale of
that which immediately preceded the historic era could
hardly have occurred in early geological time without leayv-
ing marks which geologists would have discovered. Were
the “till” now covering the glaciated region to be con-
verted into rock, its character would be unmistakable, and
the deposit is so extensive that it could not escape notice.

In his inaugural address before the British Association
in 1880, Professor Ramsey, Director-General of the Geo-
logical Survey of Great Britain, presented a formidable

312 MAN AND THE GLACIAL PERIOD.

list of glacial observations in connection with rocks of a
remote age.* Beginning at the earliest date, he cites Pro-
fessor Archibald Geikie, one of the most competent judges,
as confident that the rounded knobs and knolls of Lauren-
tian rocks exposed over a large region. in northwestern
Scotland, together with vast beds of coarse, angular, un-
stratified conglomerates, are unquestionable evidences of
glacial action at that early period. Masses of similar con- —
glomerates, resembling consolidated glacial boulder-beds,
occur also in the Lower Silurian formation at Corswall,
England. In Dunbar, Scotland, Professor Forbes also _
found, in formations of but little later age than the Coal
period, “ brecciated conglomerates, consisting of pebbles
and large blocks of stone, generally angular, embedded in
a marly paste, in which some of the pebbles are as well
scratched as those found in medial moraines.” In forma-
tions of corresponding antiquity the geologists of India
have found similar boulder-beds, in which some of the
blocks are polished and striated.

Still, this evidence is less abundant than we should ex-
pect, if there had been the repeated Glacial epochs supposed
by Mr. Croll’s astronomical theory ; and it is by no means
impossible that the conglomerates of scratched stones
described by Professor Ramsey in Great Britain, and by
Messrs. Blandford and Medlicott in India, may have re-
sulted from local glaciers coming down from mountain-
chains which have been since removed by erosion or subsi-
dence. We are not aware that any incontestable evidence
has been presented in America of any glaciation previous
to that of the Glacial period.

Upon close consideration, also, it appears that Mr.
Croll’s theory has not properly taken into account the
anomalous distribution of heat which we actually find to
take place on the surface of the earth. He has done good

* Nature (August 26, 1880), vol. xxii, pp. 388, 389.

THE CAUSE OF THE GLACIAL PERIOD. 313

service in showing what an enormous transfer of heat
there is from the southern to the northern Atlantic by
means of the Gulf Stream, estimating that the heat con-
veyed by the Gulf Stream into the Atlantic Ocean is equal
to one fifth of all possessed by the waters of the North At-
lantic ; or to the heat received from the sun upon a mill-
ion and a half square miles at the equator, or two million
square miles in the temperate zone. “The stoppage of
the Gulf Stream would deprive the Atlantic of 77,479,-
650,000,000,000,000 foot-pounds of energy in the form of
heat per day.”

Among the objections which bear against this ingen-
ious theory is one which will appear with great foree when
we come to discuss the date of the Glacial period, when
we shall show that even Professor Hitchcock’s supposition
that the lingering effects of the last great eccentricity of
the earth’s orbit, continued down to forty thousand years
ago, is not sufficient to account for the recentness of the
close of the period as shown by abundant geological evi-
dence. It is certainly not more than ten or fifteen thou-
sand years ago that the ice finally melted off from the Lau-
rentian highlands; while on the Pacific coast the period
of glaciation was still more recent.

From inspection of the accompanying map the main
point of Mr. Croll’s reasoning may be understood. It
will be seen that the direction of the currents in the cen-
tral Atlantic is largely determined by the contour of the
northeastern coast of South America. From some cause
the southeast trade-winds are stronger than the northeast,
and their force is felt in pushing the superficial currents
of warm water farther north than Cape St. Roque, the
eastern extremity of Brazil. As the direction of the
South American coast trends rapidly westward from this
point to the Isthmus of Panama,the resultant of the forces
is a strong current northwestward into the cul-de-sac of
the Gulf of Mexico, from which there is only the one

314 MAN AND THE GLACIAL PERIOD.

outlet between Cuba and the peninsula of Florida.
Through this the warm water is forced into the region
where westerly winds prevail, and spreads its genial in-
fluence far to the northward, modifying the climate of
the British Isles, and even of far-off Norway.

we Sa
G 4
Ny Ys
sr |
\ y
WN We ; NUYS NE: som 5
= & “i “i i
wx

Fie. 100.—Map showing course of currents in the Atlantic Ocean: 6 and 0’ are
currents set in motion by opposite trade-winds ; meeting, they produce the
equatorial current, which divides into ¢ and ¢’, continuing on as @ and @’ and e.

But why are the southeast trade-winds of the Atlantic
stronger than the northeast? The ultimate reason, of
course, is to be found in the fact that the northern hemi-
sphere is warmer than the southern. The atmosphere
over the northern-central portion of the Atlantic region
is more thoroughly rarefied by the sun’s heat than is that
over the region south of the equator. ‘The strong south-
east trades are simply the rush of atmosphere from the

a i
‘

THE CAUSE OF THE GLACIAL PERIOD, 315

South Atlantic to fill the vacuum caused by the heat of
the sun north of the equator.

But, again, why is this? Because, says Mr. Croll, we
are now in that stage of astronomical development favour-
able to the increased warmth of the northern hemisphere.
In the northern hemisphere the summers are longer than
the winters. Perihelion occurs in winter and aphelion in
summer. ‘his is the reason why the North Atlantic is
warmer than the South Atlantic, and why the trade-winds
of the south are drawn to the north of the equator. Ten
thousand five hundred years ago, however, the conditions
were reversed, and the greater rarefaction of the atmos-
phere would have taken place south of the equator, thus
drawing the trade-winds in that direction.

By again inspecting the map, one will see how far-
reaching the effect on the climate of northern countries
this change in the prevalences of the trades would have
been. Then, instead of having the northwest current
leading along the northeast coast of South America into
the Gulf of Mexico augmented by the warm currents cir-
culating south of the equator, the warm currents of the
north would have been pushed down so far that they
would augment the current running to the southwest be-
yond Cape St. Roque, along the southeast shore of South
America; thus the northern portion of the Atlantic,
instead of robbing the southern portion of heat, would
itself be robbed of its warm currents to contribute to the
superfluous heat of the South Atlantic.

This theory is certainly very ingenious. There is a
weak point init, however. Mr. Croll assumes that when
the winters of the northern hemisphere occur in aphelion,
they must necessarily be colder than now. But, evidently,
this assertion implies a fuller knowledge than we possess
of the laws by which the heat received from the sun is
distributed over the earth.

For it appears from observation that the equator is by

316 MAN AND THE GLACIAL PERIOD.

no means so hot now as, theoretically, it ought to be, and
that the arctic regions are not so cold as, according to
theory, they should be, and this in places which could not
be affected by oceanic currents. For example, at Iquitos,
on the Amazon, only three hundred feet above tide, three
degrees and a half south of the equator, and more than a
thousand miles from the Atlantic (so that ocean-currents
cannot abstract the heat from its vicinity), the mean
yearly temperature is but 78° Fahr.; while at Verkhojansk,

in northeast Siberia, which is 67° north of the equator,

and is situated where it is out of the reach of ocean-cur-
rents, and where the conditions for the radiation of heat
are most favourable, and where, indeed, the winter is the
coldest on the globe (January averaging — 56° Fahr.), the
mean yearly temperature is two degrees and a half above
zero; so that the difference between the temperature upon
the equator and that at the coldest point on the sixty-
seventh parallel is only about 75° Fahr.; whereas, if tem-
perature were in proportion to heat received from the sun,
the difference ought to be 172°. Again, the difference
between the actual January temperature on the fiftieth
parallel and that upon the sixtieth is but 20° Fahr.,
whereas, the quantity of solar heat received on the fiftieth
parallel during the month of January is three times that
received upon the sixtieth, and the difference in tempera-
ture ought to be about 170° Fahr. upon any known law
in the case.

- Woeikoff, a Russian meteorologist, and one of the
ablest critics of Mr. Croll’s theory, and to whom we are
indebted for these facts, ascribes the greater present
warmth of the northern Atlantic basin, not to the astro-

nomical cause invoked by Mr. Croll, but to the relatively
small extent of sea in the middle latitudes of the northern ~

hemisphere. The extent and depth of the oceans of the
southern hemisphere would of themselves give greater
steadiness and force to its trade-winds, and lead to a gen-

THE CAUSE OF THE GLACIAL PERIOD. 317

eral lowering of the temperature; so that it is doubtful
if the astronomical causes introduced by Mr. Croll, even
with Dr. Ball’s re-enforcement, would produce any appreci-
able effect while the distribution of land and water re-
mains substantially what it is at the present time.

Still another variation in the astronomical theory has
been set forth and defended by Major-General A. W.
Drayson, F.R. A.S., instructor in the Royal Military
School at Woolwich, England. He contends that what
has been called the precession of the equinoxes, and sup-
posed to be ‘“‘a conical movement of the earth’s axis in a
circle around a point as a centre, from.which it continu-
ally decreases its distance,” * is really a second rotation of
the earth about its centre. As a consequence of this
second rotation, he endeavours to show that the inclina-
tion of the earth’s axis varies as much as 12°; so that,
whereas the Arctic and Antarctic Circles and the tropics
extend to only about 23° from the poles.and the equator,
respectively, about thirteen thousand five hundred years
ago they extended more than 35°; thus bringing the
frigid zones in both cases 12° nearer the equator than
now. This, he contends, would have produced the Gla-
cial period at the time now more generally assigned to it
by direct geological evidence.

The difficulty with this theory, even if the mathemati-
cal calculations upon which it is based are correct, would
be substantially the same as those already urged against
that of Mr. Croll. It is specially difficult to see how
General Drayson would account for the prolonged tem-
perate climate in high northern latitudes during the
larger part of the Tertiary epoch.

It will be best to turn again to the map to observe the
possible effect upon the Gulf Stream of a geological event
of which we have some definite evidence, and which

* Untrodden Ground in Astronomy and Geology, p. 26.
22

318 MAN AND THE GLACIAL PERIOD.

is adduced by Mr. Upham and others as one of the
important probable causes of the Glacial period, namely,
the subsidence of the Isthmus of Panama and the adja-
cent narrow neck of land connecting North with South
America. It will be seen at a glance that a subsidence
sufficient to allow the northwest current of warm water,
pushed by the trade-winds along the northeast shore of

South America, to pass into the Pacific Ocean, instead of |

into the Gulf of Mexico, would be a cause sufficient to
produce the most far-reaching results; it would rob the

North Atlantic of the immense amount of heat and moist-

ure now distributed over it by the Gulf Stream, and would
add an equal amount to the northern Pacific Ocean, and
modify to an unknown extent the distribution of heat and
moisture over the lands of the northern hemisphere.

The supposition that a subsidence of the Isthmus of
Panama was among the contributing causes of the Glacial
period has been often made, but without any positive
proof of such subsidence. From evidence which has re-
cently come to light, however, it is certain that there has
actually been considerable subsidence there in late Ter-
tiary if not in post-Tertiary times. This evidence is fur-
nished by Dr. G@. A. Maack and Mr. William M. Gabb in
their report to the United States Government in 1874
upon the explorations for a ship-canal across the isthmus,
and consists of numerous fossils belonging to existing
species which are found at an elevation of 150 feet above
tide. As the dividing ridge is more than 700 feet above
tide, this does not positively prove the point, but so much
demonstrated subsidence makes it easy to believe, in the
absence of contradictory evidence, that there was more,
and that the isthmus was sufficiently submerged to permit
a considerable portion of the warm equatorial current
which now passes northward from the Caribbean Sea and
the Gulf of Mexico to pass into the Pacific Ocean.

An obvious objection to the theory of a late Tertiary

THE CAUSE OF THE GLACIAL PERIOD. 319

or post-Tertiary subsidence of the Isthmus of Panama
presents itself in the fact that there is at present a com-
plete diversity of species between the fish inhabiting the

TV1e. 101.—Map showing how the lend clusters about the north pole.

waters upon the different sides of the isthmus. If there
had been such a subsidence, it seems natural to suppose

320 MAN AND THE GLACIAL PERIOD.

that Atlantic species would have migrated to the Pacific
side and obtained a permanent lodgment there, and that
Pacific species would have found a congenial home on the
Atlantic side. It must be confessed that this is a serious
theoretical difficulty, but perhaps not imsuperable. For
it is by no means certain that colonists from the heated
waters of the Caribbean Sea would become so permanently
established upon the Pacific side that they could maintain
themselves there upon the re-establishment of former
conditions. On the contrary, it seems reasonable to sup-
pose that upon the re-elevation of the isthmus the north-
ern currents, which would then resume their course, would
bring back with them conditions unfavourable to the At-
lantic species, and favourable to the competing species
which had only temporarily withdrawn from the field, and
which might now be better fitted than ever to renew the
struggle with their Atlantic competitors. It is by no
means certain, therefore, that with the re-establishment
of the former conditions there would not also be a re-
establishment of the former equation of life upon the two
sides of the isthmus.

Mr. Upham’s theory involves also extensive elevations
of land in the northern part of America; in this respect
agreeing with the opinions early expressed by Professors
J. D. Dana and J. 5S. Newberry. Of the positive indica-
tions of such northward elevations of land we have already
spoken when treating in a previous chapter of the fiords
and submerged channels which characterise northern
Europe and both the eastern and the western coasts of
North America. But in working out the problem the
solution is only half reached when we have got the Gulf
Stream into the Pacific Ocean, and the land in the north-
ern part of the continents elevated to some distance above
its present level. There is still the difficulty of getting
the moisture-laden currents from the Pacific Ocean to
earry their burdens over the crest of the Sierra Nevada

THE CAUSE OF THE GLACIAL PERIOD. 321

and Rocky Mountains and to deposit them in snow upon
the Laurentian highlands. An ingenious supplement to
the theory, therefore, has been brought forward by Pro-
fessor Carpenter, who suggests that the immense Tertiary
and post-Tertiary lava-flows which cover so much of the
area west of the Rocky Mountains were the cause of the
accumulations of snow which formed the Laurentide
Glacier. This statement, which at first seems so para-
doxical as to be absurd, appears less so upon close exami-
nation.

The extent of the outflows of lava west of the Rocky
Mountains is almost beyond comprehension. Literally,
hundreds of thousands of square miles have been covered
by them to a depth in many places of thousands of
feet. These volcanic eruptions are mostly of late date,
beginning in the middle of the Tertiary and culminating
probably about the time of the maximum extent of the
Laurentide Glacier. Indeed, so nearly contemporaneous
was the growth of the Laurentide Glacier with these out-
flows that Professor Alexander Winchell had, with a
good deal of plausibility, suggested that the outflows of
the eruptions of lava were caused by the accumulation of
ice over eastern British America. His theory was that
the three million cubic miles of ice which is proved to
have been abstracted from the ocean and piled up over that
area was so serious a disturbance of the equilibrium of
the earth’s crust that it caused great fissures to be opened
along the lines of weakness west of the Rocky Mountains,
and pressed the liquid lava out, as the juice is pressed
out of an orange in one place by pressing upon the rind
in another.

Professor Carpenter’s view is the exact reverse of Pro-
fessor Winchell’s. Going back to those orographic changes
which produced the lava-flows and the elevation of the
northern part of British America, he thinks the problem
of getting the moisture transferred from the Pacific

822 MAN AND THE GLACIAL PERIOD.

Ocean to the Canadian highlands is solved by the lava-
flows west of the Rocky Mountains. This immense exu-
dation of molten matter was accompanied by an enormous
liberation of heat, which must have produced significant
changes in the meteorological conditions.

The moisture of the atmosphere is precipitated by
means of the condensation connected with a lowering of ~
its temperature. Ordinarily, therefore, when moist winds
from an oceanic area pass directly over a lofty mountain-
chain, the precipitation takes place immediately, and the —
water finds its way back bya short course to the sea.
This is what now actually occurs on the Pacific coast.
The Sierra Nevada condense nearly all the moisture; so
that very little falls on the vast area extending from their
summits eastward to the Rocky Mountains. All that re-
gion is now practically a desert land, where the evapora-
tion exceeds the precipitation. In Professor Carpenter’s
view the heat radiated from the freshly exuded lava is
supposed to have prevented the precipitation near the
coast-line, and to have helped the winds in earrying it
farther onward to the northeast, where it would be con-
densed upon the elevated highlands, upon which the
snows of the great Laurentide Glacier were collected.

It is not necessary for us to attempt to measure the
amount of truth in this subsidiary hypothesis of Professor
Carpenter, but it illustrates how complicated are the con-
ditions which have to be considered before we rest securely
upon any particular hypothesis. The unknown elements
of the problem are so numerous, and so far-reaching in
their possible scope, that a cautious attitude of agnosti-
cism, with respect to the cause of the Glacial period, is
most scientific and becoming. Still, we are ready to go so
far as to say that Mr. Upham’s theory comes nearest to
giving a satisfactory account of all the phenomena, and it
is to this that Professor Joseph Le Conte gives his cau-
tious approval,

PLIOCENE

THE CAUSE OF THE GLACIAL PERIOD. 323

Summarily stated, this theory is, that the passage from
the Tertiary to the Quaternary or Glacial period was char-
acterised by remarkable oscillations of land-level, and by
corresponding changes of climate, and of ice accumula-
tion in northern regions; that the northern elevation was
connected with subsidence in the equatorial regions; that
these changes of land-level were both initiated and, in the
main, continued by the interior geological forces of the
globe; but that the very continental elevation which
mainly brought on the Glacial period added at length, in
the weight of the ice which accumulated over the elevated
region, a new force to hasten and increase the subsidence,
which would have taken place in due time in the natural
progress of the orographic oscillations already begun.
Professor Le Conte illustrates the subject by the following
diagram, which, for simplicity’s sake, treats the Glacial

_—— — — —
—— _
——
~

=
~
ae
~

GLACIAL CHAM FAN ESSE PRESENT

Fie. 102.

epoch as one; the horizontal line, A B, represents time
from the later Phocene until now; but it also represents
the present condition of things both as to land-level and
as to ice-accumulation. The full line, ¢ d e, represents
the oscillations of land (and presumably of temperature)
above and below the present condition. The broken line
represents the rise, culmination, and decline of ice-accu-
mulation. The dotted line represents the crust-move-
ment as it would have been if there had been no ice-accu-
mulation.

It is seen from the diagram that the ice-accumulation
culminated at a time when the land, under the pressure
of the ice-load, had already commenced to subside; and

Erocus.

RECENT or

TERRACE.

(Mostly within the

PLEISTOCENE PERIOD.

GLACIAL PEeRiop or IcE AGE.

period of tradi-
tional and writ-
ten history.)

CHAMPLAIN.

(Close of the
second Glacial
epoch.)

SECOND
GLACIAL.

INTER-
GLACIAL.

(Longest epoch
of this era.)

First
GLACIAL.

EASTERN PROVINCES AND
NEW ENGLAND.

Succession of Epochs, Glacial and Fluvial Deposits, and

MIDDLE AND SOUTHERN
ATLANTIC STATES.

Rise of the land to its present
height, or somewhat higher, soon
after the departure of the ice.
Rivers eroding their glacial flood-
plains, leaving remnants as ter-
races. Warmer climate than now.
probably due to greater Gulf
Stream, formerly permitted south-
ern moilusks to extend to Gulf of
St. Lawrence, now represented by
isolated colonies.

Continued subsidence of coast
at New York and southward, and
rise of the mountainous belt. by
displacement along the fall line
of the rivers. Much erosion of
the Columbia formation since cul-
mination of second Glacial epoch;
sedimentation in bays, sounds,
and estuaries.

Land depressed under _ ice-
weight; glacial recession; con-
tinued deposition of upper till
and deep flood-plains of gravel,
sand and clay (modified drift).
Terminal moraines marking pauses
or readvance during ceneral re-
treat of ice. Marine submergence,
150 to 230 feet on coast of Maine,
0 to 520 feet in Gulf and valley of
St. Lawrence.

Second great uplift of the land,
3.000 to 4,000 feet higher than
now; snow fall again all the year;
ice probably two miles thick on
Laurentide highlands, and extend-
ing somewhat farther south here
than in first glaciation. Lower
till (ground moraine), and upper

till (englacial drift). Terminal
moraines, kames, osars, valley
drift.

Ice-sheet melted here; proba-
bly not more ice in arctic regions
than now.

Fluvial and lacustrine deposits
of this time, with those of the
first Glacial epoch, were eroded
by the second glaciation.

Less subsidence in Jatitude of
New York and southward than at
north; lower Hudson Valley, and
part of its present submarine con-
tinuation, above sea-level. Gravel
and sand deposits from englacial
drift in Delaware and Susquehan-
na Valleys, inclosing abundant
human implements at Trenton,
N.d

Renewal of great continental
elevation (3,000 feet in latitude of
New York and Philadelphia}, of
excessive snowfall and rains, and
of wide-spread fluvial deposits, the
Columbia formation, on thecoastal
plain, during early part of this
epoch, Implements of man at
Claymont, Del.

Depression, but generally not to
the present level. Deep channels
cut in the bed-rocks by the Dela-
ware, Susquehanna, Potomac, and
other rivers. The Appomattox
deposits much eroded.

Relative length of this epoch
made known by McGee irom

. |study of this region.

Begun by high continental up-
lift, ‘cool ‘climate and snowfall

throughout the year, producing)

ice-sheet. Much glacial erosion
and transportation; till and strati-
fied deposits. Ended by depres-
sion of land; return of warm cli-
mate, with rain; final melting of
the ice. Isthmus of Panama
probably submerged (Gulf Stream
smaller), and again in second
Glacial epoch.

Continental elevation ; erosion
of Delaware and Chesapeake Bays,
and of Albemarle and Pamlico
Sounds. Plentiful snowfall on
the southern Appalachian Mount-
ains; snows melted in summer,
and heavy rains, producing broad
river-floods, with deposition of the
Appomattox formation.

ces

Changes in Altitude

and Climate, during the Quaternary Fra.

Mississippi BASIN AND
NORTHWARD.

Terracing of river valleys.
Northward rise of area of
Lake Agassiz nearly com-
plete before the ice was melt-
ed on the country crossed
by Nelson River; but rise
about Hudson Bay is still)
going on; 7,000 to 8,000 years
since ice- melting uncovered
Niagara and falls of St. An-
thony.

Abundant deposition of en-
glacial drift.
ments in river gravels of
Ohio, Ind., and Minn. Lau-|
rentian lakes held at higher)
levels, and Lake Agassiz|
formed in Red River basin, by)
barrier of retreating ice, with
outlets over lowest points of|
their present southern water-|
shed. Marine submergence
300 to 500 feet on southwest
side of Hudson Bay.

Ice-sheet here less exten-
sive than in the first Glacial)
epoch, and not generally bor-|
dered as then by lakes in val-
leys which now drain south-
ward.

Terminal moraines at ex-!]
treme limit of the ice-ad-)
vance, and at ten or more
stages of halt or readv ance)
in its retreat.

Depression nearly to pres-|
more|

ent level southward ;
northward, but followed there)
by differential uplift of 800 or
1,000 feet. Great erosion of
loess and other modified drift,
and of ‘‘ Orange Sand.” Val:
leys of this. epoch, partly
filled with later till, are
marked by chains of lakes in
southern Minnesota.

Pliocene elevation of con-
tinent brought to culmination
at beginning of Quaternary;
era ; this whole basin proba-
bly then uplifted 3.000 feet ;
excessive snowfall and rain;
deposition of the “ Orange|
Sand.” Ice-sheet south to
Cincinnati and St. Louis, at!
length depressing the earth’s)
crust beneath it; slackened
river floods and shallow lakes,
forming the loess.

Stone imple-|

CORDILLERAN REGION, EUROPE AND ASIA.

Including a stage of con-| Erosion and terracing of
siderable uplift, with return stratified drift in river valleys.
of humid conditions, Alpine,\Land passage of European
glaciation (third Glacial) ‘flora to Greenland ; succeed-
epoch), and the second great) ied by subsidence there, ad-
rise of Lakes Bonneville and mitting warm currents to
Lahontan. Yery recent sub-| Arctic Sea. Minor climatic
sidence and change to pres-|changes, including a warmer
ent aridity. stage than now. Upper and
outer portions of Indo-Gan-
getic alluvial plain; extensive
deposits of Hwang Ho, and
destructive changes of its
course.

Depression probably al-| Final departure of the ice-
most to the present level.|sheets; glacial rivers form-
Restoration of arid climate ;ing eskersand kames. Loess
nearly or quite complete. deposited while the region of
evaporation of Lakes Bonne- the Alps was depressed lower
ville and Lahontan. Forma- than now. Upper (englacial)
tion of the ‘adobe’ con- till, and asar, of Sweden.
tinuing through the second Marine submergence 500 to
Glacial, Champlain, and Re-'600 feet in Scotland, Scandi-
cent epochs. navia, and Spitzbergen.

Probable uplift 3,000 feet,
shown by submerged valleys
near Cape Mendocino. Sec-|
ond ice-sheet on British Co-
umbiaand Vancouver Island;|extensive than in first Glacial
local glaciation of Rockyjepoch. Oscillations of ice-
Mountains, Cascade range,|front; British Lower and
and Sierra’ Nevada, south to Upper bowlder-clays, the
latitude 37°. First great rise Chalky, Purple. and Hessle
of Lakes Bonneville and La-|bowlder-clays. Terminal mo-
‘hontan. raines in Germany.

Second elevation and gen-
eral glaciation of northwest-
ern Europe: the ice-sheets of
Great Britain probably more

Continentaldepression. Ar-| Recession, or probably com-

id climate. Long-continued|plete departure, of the ice-

denudation of the mountains: sheets.

resulting very thick subaérial| Land connection between

\deposits of the ‘‘ adobe.’ Europe and Africa, permit-
intermittent volcanic ac-|ting southern animals to ex-

tion in various parts of this'tend far northward.

region, througheut the Qua-| Erosion of the Somme Val-

ijternary era to very recent ley below its oldest imple-

times, and liable to break ment-bearing gravels.

forth again.

| Latest rise (3.000 feet) of} Uplift and glaciation of
lthe Colorado Cafion district.|northwestern Europe; manxi-
Sierra Nevada and _ other!mum elevation, 2.500 feet or
\Great Basin mountain-ranges) ‘more (depth of “the Skager
formed by immense uplifts, Rack) ; France and Britain
i\with faulting. California riv-;united with the Farde Isl-
er-courses changed ; humanijands, Iceland, and Green-
‘bones and implements in the'land. Uplifts of the Hima-
old river gravels, lava-cov-|layas and other mountain-
ered. Ice-sheet on British Co-|ranges attendant on both
‘umbia; logai glaciers south- ‘Glacial epochs.

ward.

326 MAN AND THE GLACIAL PERIOD.

that the subsidence was greatest at a time when the press-
ure had already begun to diminish. But the fact that
the land, after the removal of the ice-load, did not return
again to its former height in the Pliocene, is proof posi-
tive that there were other and more fundamental causes
of crust-movement at work besides weighting and light-
ening. ‘The land did not again return to its former level
because the cycle of elevation, whatever its cause, which -
commenced in the Pliocene and culminated in the early
Quaternary, had exhausted itself. If it had not been for
the ice-load interfering with and modifying the natural
course of the crust-movement determined previously and
primarily by other and probably internal causes, the lat-
ter would probably have taken the course represented by
the dotted line. It would have risen higher and culmi-
nated later, and its curve would have been of simpler
form.

We append a carefully prepared table by Mr. Warren
Upham, showing ‘the probable changes in altitude and
climate during the Quaternary era. *

On the part of many the theory here provisionally
adopted will be regarded with disfavour by reason of a dis-
inclination to supposing any great recent changes of level
in the continental areas. So firmly established do the
continents appear to be, that it seems like invoking an
inordinate display of power to have them exalted for the
sake of producing a Glacial period. Due reflection, how-
ever, will make it evident that within certain limits the
continents are exceedingly unstable, and that they have
displayed this instability to as great an extent in recent

* On page 106 and sequel I have summarised the reasons which
lead me to discard the Inter-Glacial epoch, and to look upon the
whole Glacial period as constituting a grand unity with minor
episodes. It does not yet seem to me that the duality of the period
is proved. On the contrary, Mr. Kendall’s chapter on the Glacial
phenomena of Great Britain strongly confirms my view.

THE CAUSE OF THE GLACIAL PERIOD. 327

geological times as they have done in any previous geo-
logical periods. When one reflects, also, upon the size
of the earth, a continental elevation of 3,000 or 4,000 feet
upon a globe whose diameter is more than 40,000,000 feet
is an insignificant trifle. Ona globe one foot in diameter
it would be represented by a protuberance of barely one
thousandth of an inch. A corresponding wrinkle upon a
large apple would require a magnifying-glass for its de-
tection. Moreover, the activity of existing volcanoes, the
immense outflows of lava which have taken place in the
later geological periods, together with the uniform increase
of heat as we penetrate to deeper strata in the crust of
the earth—all point toa condition of the earth’s interior
that would make the elevations of land which we have
invoked for the production of the Glacial period easily
credible. Physicists do not, indeed, now hold to the entire
fluidity of the earth’s interior, but rather to a solid centre,
where gravity overcomes the expansive power of heat, and
maintains solidity even when the heat is intense. But
between the cooling crust of the earth’s exterior and a
central solid core there is now believed to be a film where
the influences of heat and of the pressure of gravity are
approximately balanced, and the space is occupied by a
half-melted or viscous magma, capable of yielding to a
slow pressure, and of moving in response to it from one
portion of the enclosed space to another where the press-
ure is for any cause relieved.

Asaresult of prolonged enquiries respecting the na-
ture of the forces at work both in the interior and upon
the exterior of the earth, and of a careful study of the
successive changes marking the geological period, we are
led to believe that the continental elevations necessary to ~
produce the phenomena of the Glacial period are not
only entirely possible but easily credible, and in analogy
with the natural progress of geological history. In the
first place, it is easy to see that two causes are in operation

328 MAN AND THE GLACIAL PERIOD.

to. produce a contraction of the earth’s volume and a
shortening of its diameter. Heat is constantly being ab-
stracted from the earth by conduction and radiation, but
perhaps to a greater extent through ceaseless volcanic
eruptions which at times are of enormous extent. It re-
quires but a moment’s thought to see that contraction of
the volume of the earth’s interior means that the hard-
ened exterior crust must adjust itself by wrinkles and
folds. For a long period this adjustment might show
itself principally in gentle swells, lifting portions of the.
continents to a higher level, accompanied by correspond-
ing subsidence in other places. This gradually accumu-
lating strain would at length be relieved along some line of
special weakness in the crust by that folding process which
has pushed up the great mountain systems of the world.

Careful study of the principal mountain systems shows
that all the highest of them are of late geological origin.
Indeed, the latter part of the Tertiary period has been
the great mountain-building epoch in the earth’s history.
The principal part of the elevation of the Andes and the
Rocky Mountains has taken place since the middle of the
Tertiary period. In Europe there is indubitable evidence
that the Pyrenees have been elevated eleven thousand feet
during the same period, and that the western Alps have
been elevated thirteen thousand feet in the same time.
The Carpathians, the western Caucasus, and the Hima-
layas likewise bear explicit evidence to the fact that a
very considerable portion of their elevation, amounting to
many thousand feet, has been effected since the middle of
the Tertiary period, while a considerable portion of this
elevation of the chiefest mountain systems of the world
has occurred in what would be called post-Tertiary time—
that is, has been coincident with a portion of the Glacial
period.

The Glacial period, however, we suppose to have been
brought about, not by the specific plications in the earth’s

THE CAUSE OF THE GLACIAL PERIOD. 329

crust which have produced the mountain-chains, but by
the gentler swells of larger continental areas whose strain
was at last relieved by the folding and mashing together
of the strata along the lines of weakness now occupied by
the mountain systems. The formation of the mountains
seems to have relieved the accumulating strain connected
with the continental elevations, and to have brought about
a subsequent subsidence.

Doubtless, also, correlated subsidences and elevations
of the earth’s crust have been aided by the transfer of the
sediment from continental to oceanic areas, and, as already
suggested, during the Glacial period by the transfer of
water evaporated from the surface of the ocean to the ice-
fields of the glaciated area. For example, present erosive
agencies are lowering the level of the whole Mississippi
basin from the Alleghanies to the Rocky Mountains at the
rate of a foot in five thousand years. All this sediment
removed is being transferred to the ocean-bed. Present
agencies, therefore, if not counteracted, would remove the
whole continent of America (whose average elevation
above the sea is only 748 feet) in less than four million
years; while the great rivers which descend in all direc-
tions from the central plateau of Asia are transferring
sediment to the ocean from two to four times as fast as
the Mississippi is, and the Po is transferring it from the
Alss to the Adriatic fully seven times as fast as the Mis-
sissippi 1s from its basin to the Gulf of Mexico. ‘This
rapid transfer of sediment from the continents to the
ocean is producing effects in disturbing the present equi-
[ibrium of the earth’s crust, which are too complicated
for us fully to calculate; but it is by no means improb-
able that when accumulating for a considerable length of
time, the ultimate results may be very marked and _ per-
haps sudden in their appearance.

The same may also be said of the accumulation of ice
during the Glacial period. The glaciated areas of North

330 MAN AND THE GLACIAL PERIOD.

America and Europe combined comprise about six mill-
ion square miles. At a moderate estimate, the ice was
three-quarters of a mile deep. Here, therefore, there
would be between four and five million cubic miles of
water, which had first relieved the ocean-beds of the press-
ure of its weight, and then concentrated its force over
the elevated areas of the northern hemisphere. This dis-
turbance of the equilibrium, by the known transfer of
foree from one part of the earth’s crust to another, cer-
tainly gives much plausibility to the theory of Jamieson,
Winchell, Le Conte, and Upham, that the Glacial period
partly contained in itself its own cure, and by the weight
of its accumulated weight of ice helped to produce that
depression over the glaciated area which at length ren-
dered the accumulation of ice there impossible.

This general view of the known causes in operation
during the Glacial period will go far towards answering
an objection that has probably before this presented itself
to the reader’s mind. It seems clear that the Glacial
period in the southern hemisphere has been nearly con-
temporaneous with that of the northern. The Glacial
period proper of the southern hemisphere is long since
passed. The existing glaciers of New Zealand, of the
southern portion of the Andes Mountains, and of the
Himalaya Mountains are but remnants of those of former
days. In the hght of the considerations just presented,
it would not seem improbable that the same causes should
produce these similar effects in the northern and the
southern hemisphere contemporaneously. At any rate, it
would not seem altogether unlikely that the pressure of
ice during the climax of the Glacial period upon the
northern hemisphere (which, as we have seen, there is
reason to believe aided in the depression of the continent
to below its present level in the latter part of the Glacial
period) should have contributed towards the elevation of
mountains in other parts of the world, and so to the

THE CAUSE OF THE GLACIAL PERIOD. 331

temporary enlargement of the glaciers about their sum-
mits.

Nor are we wholly without evidence that these read-
justments of land-level which have been carried on so
vigorously since the middle of the Tertiary period are
still going on with considerable though doubtless with
diminished rapidity. There has been a re-elevation of
the land in North America since the Glacial period
amounting to 230 feet upon the coast of Maine, 500 feet
in the vicinity of Montreal, from 1,000 to 1,600 feet in
the extreme northern part of the continent, and in Scan-
dinavia to the extent of 600 feet. In portions of Scandi-
navia the land is now rising at the rate of three feet in a
century. Other indications of even the present instability
of the earth’s surface occur in numbers too numerous to
mention.*

But, while we are increasingly confident that the main
eauses of the Glacial period have been changes in the rela-
tive relation of land-levels connected with diversion of oce-
anic currents, it is by no means impossible, as Wallace +
and others have suggested, that these were combined with
the astronomical causes urged by Drs. Croll and Geikie.
By some this combination is thought to be the more proba-
ble, because of the extreme recentness of the close of the
Glacial period, as shown by the evidence which will be
presented in the following chapter. The continuance of
glaciers in the highlands of Canada, down to within a few
thousand years of the present time, coincides in a remark-
able manner with the last occurrence of the conditions
favourable to glaciation upon Mr. Croll’s theory, which
took place about eleven thousand years ago.

* Hor a convincing presentation of the views here outlined, to-
gether with abundant references to literature, see Mr. Warren Up-
ham’s Appendix to the author’s Ice Age in North America.

+ See Island Life, chapters viii and ix.

CHAPTER X.
THE DATE OF THE GLACIAL PERIOD.

In approaching the subject of glacial chronology, we
are compelled to recognise at the outset the approximate
character of all our calculations. Still, we shall find that
_ there are pretty well-defined limits of time beyond which
it is not reasonable to place the date of the close of the
Glacial period; and, where exact figures cannot be de-
termined, it may yet be of great interest and importance
to know something near the hmits within which our spec-
ulations must range.

For many years past Mr. Croll’s astronomical theory
as to the cause of the Glacial period has been considered
in certain circles as so nearly established that it has been
adopted by them as a chronological table in which to insert
a series of supposed successive Glacial epochs which are
thought to have characterised not merely the Quaternary
epoch but all preceding geological eras. What we have
already said, however, respecting the weakness of Mr.
Croll’s theory is probably sufficient to discredit it as a
chronological apparatus. We will therefore turn immedi-
ately to the more tangible evidences bearing upon the
subject. ;

The data directly relating to the length of time which
separates the present from the Glacia! period are mainly
connected with two classes of facts:

1. The amount of erosion which has been accomplished

by the river systems since the Glacial period; and 2. The
(832)

THE DATE OF THE GLACIAL PERIOD. 333

amount of sedimentation which has taken place in lakes
We will consider first the evidence

and kettle-holes.

from erosion.

The gorge below Niagara Falls affords an important
chronometer for measuring the time which has elapsed

ee

Fic. 103.—Diagram of eccentricity and precession :

=),
oN
SSeS

if | |
l i a ‘i mn <9
ae iat neat.
| Ul i aA tA | A 4 f i | i
150 loo =

THOUSAND ar AGO FROM

Absciss represents time and

ordinates, “degrees of eccentricity and also of cold. The dark and light
shades show the warmer and colder winters, and therefore indicate each
10,500 years, the whole representing a period of 800,000 years.

since a certain stage in the recession of the great North

American ice-sheet. As already shown,

the present Niag-

ara River is purely a post-glacial line of drainage;* the
preglacial outlet to Lake Erie having been filled up by
glacial Ceposits, so that, on the recession of the ice, the
lowest level between Lake Erie and Lake Ontario was in
the line of the trough of the present outlet. But, from
what has already been said, it also appears that the Niagara
River did not begin to flow until considerably after the
ice-front had withdrawn from the escarpment at Queens-
ton, where. the river now emerges from its cafion to the
low shelf which borders Lake Ontario.
period afterwards the ice continued to block up the east-
erly and northerly outlets through the valleys of the

23

For a considerable

* See above, p. 200 e¢ seg.

Queenston , a
Ny 14 OS sll eye i
S eS i
wes as
ae Hp
a gt Mi
a? iN
» 5t.-Davids
fe
Zs. =
CS}
“2
ise! Os
{ ) >,
We vie,
yon NS" lei =
Fame:
Cla EN SA)
i} Nd ( SS iy
a ow

SCALE OF MILES

Falls of NiagaraXitQ
y Meso

Struthers § Co., Engr’s, N.Y.

Fic. 104.—Map of the Niagara River below the falls, showing the buried channel
from the whirlpool to St. Davids. Small streams, a, 6, ¢, fall into the main
gorge over a rocky escarpment. No rock appears in the channel at d, but the
rocky escarpment reappears at @.

~ ee

THE DATE OF THE GLACIAL PERIOD. 335

Mohawk and of the St. Lawrence, and held the water in
front of the ice up to the level of the passes leading into
the Mississippi Valley. Niagara River, of course, was not
born until these ice-barriers on the east and northeast
melted away sufficiently to allow the drainage to take its
natural course.

Of these barriers, that across the Mohawk Valley doubt-
less gave way first. This would allow the confluent waters
of this great glacial lake to fall down, to the level of the old
outlet from the basin of Lake Ontario into the Mohawk
Valley, in the vicinity of Rome, N. Y. ‘The moment, how-
ever, that the water had fallen to this level, the plunging
torrents of Niagara would begin their work; and the
gorge extending from Queenston up to the present falls is
the work done by this great river since that point of time
in the Glacial period when the ice-barrier across the Mo-
hawk Valley broke away. |

The problem is therefore a simple one. Considering
the length of this gorge as the dividend, the object is to
find the rate of annual recession; this will be the divisor.
The quotient will be the number of years which have
elapsed since the ice first melted away from the Mohawk
Valley. We are favoured in our calculation by the sim-
plicity of the geologic arrangement.

The strata at Niagara dip slightly to the south, but
not enough to make any serious disturbance in the prob-
lem. . That at the surface, over which the water now
plunges, consists of hard limestone, seventy or eighty feet
in thickness, and this is continuous from the falls to
the face of the escarpment at Queenston, where the river
emerges from the gorge. Immediately underneath this
hard superficial stratum there is a stratum of soft rock,
of about the same thickness, which disintegrates readily.
As a consequence, the plunging water continually under-
mines the hard stratum at the surface, and prepares the
way for it to fall down, from time to time, in huge blocks,

336 MAN AND THE GLACIAL PERIOD.

which are, in turn, ground to powder by the constant com-
motion in which they are kept, and thus the channel is
cleared of débris.

Below these two main strata there is considerable
variation in the hardness of the rock, as shown in the
accompanying diagram, where 3 and 5 are hard strata
separated by a soft stratum. In view of this fact it seems
probabie that, for a considerable period in the early part
of the recession, instead of there being simply one, there
was a succession of cataracts, as the water unequally wore
back through the harder strata, numbered 5, 3, and 1;

Whirl oon

Queenstor

AKE
NTARIO

Fie. 105.—Section of strata along the Niagara gorge from the falls to the lake:
1, 3, strata of hard rock ; 2, 4, of soft rock.

but, after having receded half the distance, these would
cease to be disturbing influences, and the problem is thus
really the simple one of the recession through the strata
numbered 1 and 2, which are continuous. So uniform in
consistency are these throughout the whole distance, that
the rate of recession could never have been less than it is
now. We come, therefore, to the question of the rapidity
with which the falls are now receding.

In 1841 Sir Charles Lyell and Professor James Hall
(the State Geologist of New York) visited the falls together,
and estimated that the rate of recession could not be
greater than one foot a year, which would make the time
required about thirty-five thousand years. But Lyell
thought this rate was probably three times too large; so

THE DATE OF THE GLACIAL PERIOD. SOT

that he favoured extending the time to one hundred thou-
sand years. Before this the eminent French geologist
Desor had estimated that the recession could not have
been more than a foot in a century, which would throw
the beginning of the gorge back more than three mill-
ion years. But these were mere guesses of eminent men,
based on no well-ascertained facts; while Mr. Bakewell,
an eminent English geologist, trusting to the data fur-
nished him by the guides and the old residents of
Niagara, had, even then, estimated that the rate of re-
cession was as much as three feet a year, which would
reduce the whole time required to about ten thousand
years.

But the visit of Lyell and Hall in 1841 led to the be-
ginning of more accurate calculations. Professor Hall
soon after had a trigonometrical survey of the falls made,
from which a map was published in the State geological
report. From this and from the monuments erected, we
have had since that time a basis of comparison in which
we could place absolute confidence.

In recent years three surveys have been made: the
first by the New York State Geologists, in 1875 ; and the
third by Mr. R. 8. Woodward, the mathematician of the
United States Geological Survey, in 1886. The accom-
panying map shows the outlines of the falls at the time of
these three measurements, from 1842 to 1886. According
to Mr. Woodward, “ the length of the front of the Horse-
shoe Fall is twenty-three hundred feet. Between 1842
and 1875 four and a quarter acres of rock were worn away
by the recession of the falls. Between 1875 and 1886 a
little over one acre and a third disappeared in a similar
manner, making in all, from 1842 to 1886, about five and
a half acres removed, and giving an annual rate of reces-
sion of about two feet and a half per year for the last
forty-five years. But in the central parts of the curve,
where the water is deepest, the Horseshoe Fall retreated

RIOD.

)

MAN AND THE GLACIAL PI!

338

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THE DATE OF THE GLACIAL PERIOD. 339

between two hundred and two hundred and seventy-tive
feet in the eleven years between 1875 and 1886.”

It will be perceived that the recession in the centre of
the Horseshoe is very much more rapid than that nearer
the margin; yet this rate at the centre is more nearly the
standard of calculation than is that near the margin, for
the gorge constantly tends to enlarge itself below the falls,
and so gradually to bring itself into line with the full-
formed channel. ‘Taking all things into account, Mr.
Woodward and the other members of the Geological Sur-
vey thought it not improbable that the average rate of
actual recession in the Horseshoe Fall was as great as five
feet per annum; and that, if we can rely upon the uniform-
ity of the conditions in the past, seven thousand years is
as long a period as can be assigned to its commencement.

The only condition in the problem about which there
can be much chance of question relates to the constancy
of the volume of water flowing in the Niagara channel.
Mr. Gilbert had suggested that, as a consequence of the
subsidence connected with the closing portions of the Gla-
cial period, the water of the Great Lakes may have been
largely diverted from its present outlet in Niagara River
and turned northeastward, through Georgian Bay, French
River, and Lake Nipissing, into a tributary of the Ottawa
River, and so carried into the St. Lawrence below Lake
Ontario. Of this theory there is also much direct evi-
dence. A well-defined shore line of rounded pebbles ex-
tends, at an elevation of about fifty feet, across the col
from Lake Nipissing to the head waters of the Mattawa, a
tributary of the Ottawa; while at the junction with the
Ottawa there is an enormous delta terrace of boulders,
forming a bar across the main stream just such as would
result from Mr. Gilbert’s supposed outlet. But this outlet
was doubtless limited to a comparatively few centuries, and
Dr. Robert Bell thinks the evidence still inconclusive.*

* See Bul. Geol. Soe. Am., vol. iv, pp. 423-427, vol. v, pp. 620-626.

310 MAN AND THE GLACIAL PERIOD.

A second noteworthy glacial chronometer is found in
the gorge of the Mississippi River, extending from the
Falls of St. Anthony, at Minneapolis, to its junction with
the preglacial trough of the old Mississippi, at Fort Snel-
ling, a distance likewise of about seven miles.

Above Fort Snelling the preglacial gorge is occupied
by the Minnesota River, and, as we have before stated,
extends to the very sources of this river, and is continuous
with the southern portion of the valley of the trough of
the Red River of the North. Before the Glacial period .
the drainage of the present basin of the upper Mississippi
joined this main preglacial valley, not at Fort Snelling,
but some little distance above, as shown upon our map.*
This part of the preglacial gorge became partially filled
up with glacial deposits, but it can be still traced by the
lakelets occupying portions of the old depression, and by
the records of wells which have been sunk along the line.
When the ice-front had receded beyond the site of Min-
neapolis, the only line of drainage left open for the water
was along the course of the present gorge from Minne-
apolis to Fort Snelling.

Here, as at Niagara, the problem is comparatively
simple. The upper strata of rock consist of hard lme-
stone, which is underlaid by a soft sandstone, which, lke
the underlying shale at Niagara, is eroded faster than the
upper strata, and so a perpendicular fall is maintained.
The strata are so uniform in texture and thickness that,
with the present amount of water in the river, the rate of
recession of the falls must have been, from the beginning,
very constant. If, therefore, the rate can be determined,
the problem can be solved with a good degree of con-
fidence.

Fortunately, the first discoverer of the cataract—the
Catholic missionary Hennepin—was an accurate observer,

* See above, p. 209.

THE DATE OF THE GLACIAL PERIOD. _ 84]

and was given to recording his observations for the in-
struction of the outside world and of future generations.
From his description, printed in Amsterdam in 1704,
Professor N. H. Winchell is able to determine the pre-
eise locality of the cataract when discovered in 1680.

Again, in 1766 the Catholic missionary Carver visited
the falls, and not only wrote a description, but made a
sketch (found in an account of his travels, published in
London in 1788) which confirms the inferences drawn
from Hennepin’s narrative. The actual period of reces-
sion, however (which Professor Winchell duly takes into
account), extends only to the year 1856, at which time
such artificial changes were introduced as to modify the
rate of recession and disturb further calculations. But
between 1680 and 1766 the falls had evidently receded
about 412 feet. Between 1766 and 1856 the recession
had been 600 feet. The average rate is estimated by
Professor Winchell to be about five feet per year, and the
total length of time required for the formation of the
gorge above Fort Snelling is a little less than eight thou-
sand years, or about the same as that calculated by Messrs.
Woodward and Gilbert for the Niagara gorge.

To these calculations of Professor Winchell it does
not seem possible to urge any valid objection. It does
not seem credible that the amount of water in the Missis-
sippi should ever have been less than now, while during
the continuance of the ice in the upper portion of the
Mississippi basin the flow of water was certainly far greater
than now.

If any one is inclined to challenge Professor Win-
chell’s interpretation of the facts, even a hasty visit to
the locality will suffice to produce conviction. The com-
parative youth of the gorge from Fort Snelling up to
Minneapolis is evident: 1. From its relative narrowness,
when compared with the main valley below. This is rep-
resented by the shading upon the map. The gorge from

312 MAN AND THE GLACIAL PERIOD.

Fort Snelling up is not old enough to have permitted
much enlargement by the gradual undermining of the
superficial strata on either side, which slowly but constantly
goes on. 2. From the abruptness with which it merges
into the preglacial valley of the Muinnesota-Mississipp1.
The opening at Fort Snelling is not V-shaped, as in gorges
where there has been indefinite time for the operation of ~
erosive agencies. 3. Furthermore, the precipices lining
the post-glacial gorge above Fort Snelling are far more
abrupt than those in the preglacial valley below, and they .
give far less evidence of weathering. 4. Still, again, the
tributary streams, like the Mmnehaha River, which empty
into the Mississippi between Fort Snelling and Muinne-
apolis, flow upon the surface, and have eroded gorges of
very limited extent; whereas, below Fort Snelling, the
small streams have usually either found underground
access to the river or occupy gorges of indefinite extent.
The above estimates, setting such narrow limits to
post-glacial time in America, will seem surprising only to
those who have not carefully considered the glacial phe-
nomena of various kinds to be observed all over the glaci-
ated area. As already said, the glaciated portion of North
America is a region of waterfalls, caused by the filling up
of old channels with glacial débris, and the consequent
diversion of the water-courses. By this means the streams
in countless places have been forced to fall over preci-
pices, and to begin anew their work of erosion. Water-
falls abound in the glaciated region because post-glacial
time is so short. Give these streams time enough, and
they will wear their way back to their-sources, as the pre-
glacial streams had done over the same area, and as simi-
lar streams have done outside the glaciated region. Upon
close observation, it will be found that the waterfalls in
America are nearly all post-glacial, and that their work of
erosion has been confined to a very limited time. A fair
example is to be seen at Elyria, Ohio, in the falls of Black

THE DATE OF THE GLACIAL PERIOD. 343

River, one of the small streams which empty into Lake
Erie from the south. Its post-glacial gorge, worn in
sandstone which overlies soft shale, is only about two
thousand feet in length, and it has as yet made no ap-
proach toward a V-shaped outlet.

The same impression of recent age is made by examin-
ing the outlets of almost any of the lakes which dot the
glaciated area. ‘The very reason of the continued exist-
ence of these lakes is that they have not had time enough
to lower their outlets sufficiently to drain the water off, as
has been done in all the unglaciated region. In many
cases it is easy to see that the time during which this
process of lowering the outlets has been going on cannot
have been many thousand years.

The same impression is made upon studying the evi-
dences of post-glacial valley erosion. Ordinary streams
constantly enlarge their troughs by impinging against the
banks now upon one side and now upon the other, and
transporting the material towards the sea. It is estimated
by Wallace that nine-tenths of the sedimentary material
borne along by rivers is gathered from the immediate
vicinity of its current, and goes to enlarge the trough of
the stream. Upon measuring the cubical contents of
many eroded troughs of streams in the glaciated region,
and applying the tables giving the average amount of
‘annual transportation of sediment by streams, we arrive
at nearly the same results as by the study of the recession
of post-glacial waterfalls.

Professor L. K. Hicks, of Granville, Ohio, has published
the results of careful calculations made by him, concern-
ing the valley of Raccoon Creek in Licking County, Ohio.*
These show that fifteen thousand years would be more
than abundant time for the erosion of the immediate val-
ley adjoining that small stream. I have made and pub-

* See Baptist Quarterly for July, 1884.

34-4. MAN: AND THE GLACIAL PERIOD.

lished similar calculations concerning Plum Creek, at
Oberlin, in Lorain County, Ohio.* Like Raccoon Creek,
this has its entire bed in glacial deposits, and has had
nothing else to do since its birth but to enlarge its bor-
ders. The drainage basin of the creek covers an area of
about twenty-five square miles. Its main trough averages
about twenty feet in depth by five hundred in width, along |
a distance of about ten miles. From the rate at which
the stream is transporting sediment, it is Incredible that
it could have been at work at this process more than ten .
thousand years without producing greater results.

Calculations based upon the amount of sediment de-
posited since the retreat of the ice-sheet point to a like
moderate conclusion. When one looks upon the turbid
water of a raging stream in time of flood, and considers
that all the sediment borne along will soon settle down
upon the bottom of the lake into which the stream
empties, he can but feel surprised that the “wash” of
the hills has not already filled up the depression of the
lake. It certainly would have done so had the present
condition of things existed for an indefinite period of
time.

Naturally, while prosecuting the survey of the super-
ficial geology of Minnesota, Mr. Upham was greatly im-
pressed by the continued existence of the innumerable
lakelets that give such a charm to the scenery of that
State. Every day’s investigations added to the evidence
that the lapse of time since the Ice age must have been
comparatively brief, since, otherwise, the rains and streams
would have filled these basins with sediment, and cut out-
lets low enough to drain them dry, for in many instances
he could see such changes slowly going forward.t

Some years ago I myself made a careful estimate of the

* See Ice Age in North America, p. 469.
+ Minnesota Geological Report for 1879, p. 73.

THE DATE OF THE GLACIAL PERIOD. 345

amount of deposition and vegetable accumulation which
had’ taken place in a kettle-hole near Pomp’s Pond, in
Andover, Mass. The diameter of the depression at the rim

ttt};
A YS ZA GY
7 Lid LZ UE i: Yi

Fie. 107.—Section of kettle-hole near Pomp’s Pond, Andover, Massachusetts (see
text). (For general view of the situation, see Fig. 30, p. 78.)

Pomp’s

\

was 276 feet. The inclination of the sides was such that
the extreme depression of the apex of the inverted cone
could not have been more than seventy feet; yet the
accumulation of peat and sediment only amounted to a
depth of seventeen feet. The total amount of material
which had accumulated would be represented by a cone
ninety-six feet in diameter at the base and seventeen feet
at the apex, which would equal only a deposit of about
five feet over the present surface of the bottom. It is
easy to see that ten thousand years is a liberal allowance
of time for the accumulation of five feet of sediment in
the bottom of an enclosure like a kettle-hole, for upon
examination it is clear that whatever insoluble material
gets into a kettle-hole must remain there, since there is
no possible way by which it can get out. Now five feet is
sixty inches, and if this amount has been six thousand
years in accumulating, that would represent a rate of an
inch in one hundred years, while, if it has been twelve
thousand years in accumulation, the rate will be only one
two-hundredth of an inch per year, a film so small as to be
almost inappreciable. If we may judge from appearance,
the result would not be much different in the case of the
tens of thousands of kettle-holes and lakelets which dot
the surface of the glaciated region.

In the year 1869 Dr. E. Andrews, of Chicago, made
an important series of calculations concerning the rate
at which the waters of Lake Michigan are eating into the

346 MAN AND THE GLACIAL PERIOD.

shores and washing the sediment into deeper water or
towards the southern end of the lake. With reference to
the erosion of the shores, it appears from the work of the
United States Coast Survey that a shoulder, covered with
sixty feet of water, representing the depth at which wave-
action is efficient in erosion, extends outward from the
west shore a distance of about three miles, where the
sounding line reveals the shore of the deeper original —
lake as it appeared upon the first withdrawal of the ice.

From a variety of observations the average rate at
which the erosion of the bluffs is proceeding is found to—
be such that the post-glacial time cannot be more than
ten thousand years, and probably not more than seven
thousand.

An independent mode of calculating this period is
afforded by the accumulations of sand at the south end of
the lake, to which it is constantly drifting by the currents
of water propelled against the shores by the wind; for the
body of water in the lake is moving southward along the
shores towards the closed end in that direction, there being
a returning current along the middle of the lake. All
the railroads approaching Chicago from the east pass
through these sand deposits, and few of the observant
travellers passing over the routes can have failed to no-
tice the dunes into which the sand has been drifted by
the wind. Now, all the material of these dunes and-sand-
beaches has been washed out of the bluffs to the north-
ward by the process already mentioned, and has been
slowly transferred by wave-action to its present position.
It is estimated that south of Chicago and Grand Haven,
this wave-transported sand amounts to 3,407,451,000 cubic
yards. This occupies a belt curving around the south end
about ten miles wide and one hundred miles long

The rate at which the sand is moving southward
along the shore is found by observing the amount-annu-
ally arrested by the piers at Chicago, Grand Haven, and

THE DATE. OF THE GLACIAL PERIOD. 847

Michigan City. This equals 129,000 cubic yards for a year,
which can scarcely be more than one quarter or one fifth of
the total amount in motion. At this rate, the sand accum-
ulations at the southern end of the lake would have been
produced in a little less than seven thousand years.

“ If,” says Dr. Andrews, “‘ we estimate the total annual
sand-drift at only twice the amount actually stopped by
the very imperfect piers built—which, in the opinion of
the engineers, is setting it far too low—and compare it
with the capacity of the clay-basin of Lake Michigan, we
shall find that, had this process continued one hundred
thousand years the whole south end of Lake Michigan,
up to the line connecting Chicago and Michigan City,
would have been full and converted into dry land twenty-
five thousand years ago, and the coast-line would now be
found many miles north of Chicago.” *

It is proper to add a word in answer to an objection
which may arise in the reader’s mind, for it will doubtless
occur to some to ask why this sand which is washed out
by the waves from the bluffs is not carried inward towards
the deeper portion of the trough of the lake, thus pro-
ducing a waste which would partly counteract the forces of
accumulation at the south end. ‘The answer is found in
the fact that the south end of Lake Michigan is closed,
and that the currents set in motion by the wind are such
that there is no off-shore motion sufficient to move sand,
and, as a matter of fact, dredgings show that the sand is
limited to the vicinity of the shore.

By comparing the eroded cliffs upon Michigan and the
other Great Lakes with what occurs in similar situations
about the glacial Lake Agassiz, we obtain an interesting
means of estimating the comparative length of time occu-
pied by the ice-front in receding from the Canadian bor-
der to Hudson Bay.

* Southall’s Recent Origin of Man, p. 502.

348 MAN AND THE GLACIAL PERIOD.

As we have seen, Lake Agassiz occupied a position
quite similar in most respects to Lake Michigan. Its
longest diameter was north and south, and the same forces
which have eroded the cliffs of Lake Michigan and piled
up sand-dunes at its southern end would have produced
similar effects upon the shores of Lake Agassiz, had its
continuance been anywhere near as long as that of the
present Lake Michigan has been. But, according to Mr.
Upham, who has most carefully surveyed the whole region,
there are nowhere on the shores of the old Lake Agassiz

any evidence of eroded cliffs at all to be compared with

those fonnd upon the present Great Lakes, while there is
almost an entire lack of sand deposits about the south end
such as characterise the shore of Lake Michigan. ‘“ The
great tracts of dunes about the south end of Lake Michi-
gan belong,” as Upham well observes, ‘‘ wholly to beach ac-
cumulations, being sand derived from erosion of the west-
ern and eastern shores of the lake. . . . But none of the
beaches of our glacial lakes are large enough to make
dunes like those on Lake Michigan, though the size and
depth of Lake Agassiz, its great extent from north to
south, and the character of its shores, seem equally favor-
able for their accumulation. It is thus again indicated
that the time occupied by the recession of the ice-sheet
was comparatively brief.” *

From Mr. Upham’s conclusions it would seem that if
ten thousand years be allowed for the post-glacial existence
of Lake Michigan, one tenth of that period would be more
than sufficient to account for the cliffs, deltas, beaches,
and other analogous phenomena about Lake Agassiz. In
other words, the duration of Lake Agassiz could not have
been more than a thousand years, which gives us a meas-

* Proceedings of the Boston Society of Natural History, vol.
xxiv, p. 454; Upham’s Glacial Lakes in Canada, in Bulletin of the
Geological Society of America, vol. ii, p. 248.

THE DATE OF THE GLACIAL PERIOD. 349

ure of the rate at which the recession of the ice-front went
on after it had withdrawn to the international boundary.
The distance from there to the mouth of Nelson River is
about 600 miles. ‘The recession of the ice-front over that
area proceeded, therefore, at the average rate of about
half a mile per year.

There are many evidences that the main pericd of
glaciation west of the Rocky Mountains was considerably
later than that in the eastern part of the continent. A
portion of the facts pointing to this conclusion have been
well stated by Mr. George F. Becker, of the United States
Geological Survey.

‘“‘ No one,” he says, “who has examined the glaciated
regions of the Sierra can doubt that the great mass of the
ice disappeared at a very recent period. ‘The immense areas
of polished surfaces fully exposed to the severe climate of
say from 7,000 to 12,000 feet altitude, the insensible ero-
sion of streams running over glaciated rocks, and the fresh-
ness of erratic boulders are sufficient evidence of this.
There is also evidence that the glaciation began at no very
distant geologic date. As Professor Whitney pointed out,
glaciation is the last important geological phenomenon
and succeeded the great lava flows. There is also much
evidence that erosion has been trifling since the commence-
ment of glaciation, excepting under peculiar circum-
stances. Hast of the range, for example, at Virginia City,
andesites which there is every reason to suppose pregla-
cial have scarcely suffered at all from erosion, so that de-
pressions down which water runs at every shower are not
yet marked with water-courses, while older rocks, even of
Tertiary age and close by, are deeply carved. The rainfall
at Virginia City is, to be sure, only about ten inches, so
that rock would erode only say one third as fast as on the
California coast; but even when full allowance is made
for this difference, it is clear that these andesites must be

much younger than the commencement of glaciation in
24

350 MAN AND THE GLACIAL PERIOD.

the northeastern portion of the continent as usually esti-
mated. So, too, the andesites near Clear Lake, in Cali-
fornia, though beyond a doubt preglacial, have suffered
little erosion, and one of the masses, Mount Konocti (or
Uncle Sam), has nearly as characteristic a voleanie form
as Mount Vesuvius.” *

This view of Mr. Becker is amply sustained by many ©

other obvious facts, some of which may be easily observed
by tourists who visit the Yosemite Park. The freedom of

the abutting walls of this cafion from talus, as well as the.

freshness of the glacial scratches upon both the walls and
the floor of the tributary cafions, all indicate a lapse of
centuries only, rather than of thousands of years, since
their occupation by glacial ice.

The freshness of the high-level terraces surounding the
valleys of Great Salt Lake, in Utah, and of Pyramid and
North Carson Lakes, in Nevada, and the small amount of
erosion which has taken place since the formation of
these terraces, point in the same direction—namely, to a
very recent date for the glaciation of the Pacific coast.

_ We have already detailed the facts concerning the for-

mation of these terraces and the evidence of their probable
connection with the Glacial period. It is sufficient, there-
fore, here to add that, according to Mr. Russell and Mr.
Gilbert (two of the most eminent members of the United
States Geological Survey, who have each published mono-
graphs minutely embodying the results of their extensive
observations in this region), the erosion of present streams
in the beds which were deposited during the enlargement of
the lakes is very slight, and the modification of the shores
since the formation of the high terraces has been insignifi-
cant.

According to Mr. Gilbert: “The Bonneville shores

* Bulletin of the Geological Society of America, vol. ii, pp. 196,
197.

=

THE DATE OF THE GLACIAL PERIOD. 351

are almost unmodified. Intersecting streams, it is true,
have scored them and interrupted their continuity for
brief spaces ; but the beating of the rain has hardly left a
trace. ‘The sea-cliffs still stand as they first stood, except
that frost has wrought upon their faces so as to crumble
away a portion and make a low talus at the base. The
embankments and beaches and bars are almost as perfect
as though the lake had left them yesterday, and many of
them rival in the symmetry and perfection of their con-
tours the most elaborate work of the engineer. ‘There
are places where boulders of quartzite or other enduring
rock still retain the smooth, glistening surfaces which the
waves scoured upon them by dashing against them the
sands of the beach.

“When this preservation is compared with that of the
lowest Tertiary rocks of the region—the Pliocene beds to
which King has given the name Humboldt—the differ-
ence is most impressive. The Pliocene shore-lines have
disappeared.

“'The deposits are so indurated as to serve for building-
stone. ‘They have been upturned in many places by the
uplifting of mountains. Hlsewhere they have been divided
by faults, and the fragments, dissevered from their contin-
uation in the valley, have been carried high up on the
mountain-flanks, where erosion has carved them in typi-
cal mountain forms. ... The date of the Bonneville
flood is the geologic yesterday, and, calling it yesterday, we
may without exaggeration refer the Pliocene of Utah to
the last decace; the Eocene of the Colorado basin to the
last century, and relegate the laying of the Potsdam sand-
stone to prehistoric times.” *

Mr. Russell adds to this class of evidence that of the
small extent to which the glacial striz have been effaced

* Second Annual Report of the United States Geological Survey,
p. 188.

359 MAN AND THE GLACIAL PERIOD.

since the withdrawal of the ice from the borders of these
old lakes: “ The smooth surfaces are still scored with fine,
hair-like lines, and the eye fails to detect more than a
trace of disintegration that has taken place since the sur-
faces received their polish and striation. ... It seems
reasonable to conclude that in a severe climate like that
of the high Sierra it” (the polish) “ could not remain un- |
impaired for more than a few centuries at the most.” *

Europe does not seem to furnish so favourable oppor-
tunities as America for estimating the date of the Glacial -
period; still it is not altogether wanting in data bearing
upon the subject.

Some of the caves in which paleolithic implements
were found associated with the bones of extinct animals
in southern England contain floors of stalagmite which
have been thought by some to furnish a measure of the
time separating the deposits underneath from those above.
This is specially true in the case of Kent’s Cavern, near
Torquay, which contains two floors of stalagmite, the
upper one almost continuous and varying in thickness
from sixteen inches to five feet, the lower one being in
places twelve feet thick, underneath which human imple-
ments were found.

But it is difficult to determine the rate at which stalag-
mite accumulates. As is well known, this deposit is a
form of carbonate of lime, and accumulates when water
holding the substance in solution drops down upon the
surface, where it is partially evaporated. It then leaves a
thin film of the substance upon the floor. The rate of the
accumulation will depend upon both the degree to which
the water is saturated with the carbonate and upon the
quantity of the water which percolates through the roof
of the cavern. These factors are so variable, and so de-

* See also Mr. Upham in American Journal of Science, vol. xli,
pp. 41, 51.

THE DATE OF THE GLACIAL PERIOD. 350

pendent upon unknown conditions in the past, that it is
very difficult to estimate the result for any long period of
time. Occasionally a quarter of an inch of stalagmite
accretion has been known to take place in a cavern in a
single year, while in Kent’s Cavern, over a visitor’s name
inscribed in the year 1688, a film of stalagmite only a
twentieth of an inch in thickness has accumulated. If,
therefore, we could reckon upon a uniformity of conditions
stretching indefinitely back into the past, we could deter-
mine the age of these oldest remains of man in Kent’s
Hole by a simple sum in arithmetic, and should infer that
the upper layer of stalagmite required 240,000 years, and
the lower 576,000 years, for their growth, which would
carry us back more than 700,000 years, and some have not
hesitated to affix as early a date as this to these lowest
implement-bearing gravels.

But other portions of the cave show an actual rate of
accretion very much larger. Six inches of stalagmite is
there found overlying some remains of Romano-Saxon
times which cannot be more than 2,000 years old. As-
suming this as the uniform rate, the total time required
for the deposit of the stalagmitic floors would still be about
70,000 years. But, as we have seen, the present rates of
deposition are probably considerably less than those which
took place during the moister climate of the Glacial epoch.
Still, even by supposing the rate to be increased fourfold,
the age of this lower stratum would be reduced to only
12,000 years. So that, as Mr. James Geikie well main-
tains, ‘“‘ Even on the most extravagant assumption as to
the former rate of stalagmitic accretion, we shall yet be
compelled to admit a period of many thousands of years
for the formation of the stalagmitic pavements in Kent’s
Cavern.” * We should add, however, that there is much
well-founded doubt whether the implements found in the

* Prehistoric Europe, p. 83.

354 MAN AND THE GLACIAL PERIOD.

lowest stratum were really in place, since, according to
Dr. Evans, “ Owing to previous excavations and to the
presence of burrowing animals, the remains from above
and below the stalagmite have become intermingled.” *

An attempt was made by M. Morlot in Switzerland to
obtain the chronology of the Glacial period by studying
the deltas of the streams descending the glaciated valleys.
He paid special attention to that of the Tiniére, a stream
which flows into Lake Geneva near Villeneuve. The
modern delta of this stream consists of gravel and sand
deposited in the shape of a flattened cone, and inyestiga-
tions upon it were facilitated by a long railroad cutting
through it. ‘Three layers of vegetable soil, each of which
must at one time have formed the surface of the cone,
have been cut through at different depths.” + In the
upper stratum Roman tiles and a coin were found; in the
second stratum, unvarnished pottery and implements of
bronze; while in the lower stratum, at a depth of nineteen
feet from the surface, a human skull was found, to which
Morlot assigned an age of from 5,000 to 7,000 years.

But Dr. Andrews, after carefully revising the data, felt
confident that the time required for the whole deposit of
this lower delta was not more than 5,000 years, and that
the oldest human remains in it, which were about half
way from between the base and the surface of the cone,
were probably not more than 3,000 years old.

Still, the significance of this estimate principally arises
from the relation of the modern delta to older deltas con-
nected with the Glacial period. Above this modern delta,
formed by the river in its present proportions, there is
another, more ancient, about ten times as large, whose ac-
cumulation doubtless took place upon the final retreat of
the ice from Lake Geneva. No remains of man have been

* Stone and Flint Implements, p. 446.
+ Lyell’s Antiquity of Man, p. 28.

ey

THE DATE OF THE GLACIAL PERIOD. 300

found in this, but it doubtless corresponds in age with the
high-level gravels in the valley of the Somme, in which
the remains of man and the mammoth, together with
other extinct animals, have been found.

We do not see, however, that any very definite calcu-
lation can be made concerning the time required for its
deposition. Lyell was inclined to consider it ten times as
old as the modern delta, simply upon the ground of its
being ten times as large. On Morlot’s estimate of the age
of the modern delta, therefore, the retreat of the ice whose
melting torrents deposited the upper delta would be fixed
at 100,000 years ago, and upon Dr. Andrews’s calculation,
at about 20,000.

But it is evident that the problem is not one of simple
multiplication. The floods of water which accompanied
the melting back of the ice from the upper portions of
this valley must have been immensely larger than those
of the present streams, and their transporting power im-
mensely greater still. Hence we do not see that any con-
clusions can be drawn from the deltas of the 'Tiniére to
give countenance to extreme views concerning the date of
the close of the Glacial period.*

In the valley of the Somme the chronological data
relating to the Glacial period, and indicating a great an-
tiquity for man, have been thought to be more distinct
than anywhere else in Europe. As already stated, it is
the prevalent opinion that since man first entered the
valley, in connection with the mammoth and the other
extinct animals characteristic of the Glacial period, the
trough of the Somme, about a mile in width and a hun-
dred feet in depth, has been eroded by the drainage of its
present valley. An extensive accumulation of peat also
has taken place along the bottom of the trough of the
river since it was originally eroded to its present level.

* Lyell’s Antiquity of Man, p. 321.

356 MAN AND THE GLACIAL PERIOD.

This substance occurs all along the bottom of the valley
from far above Amiens to the sea, and is in some places
more than thirty feet in depth. The animal and vegeta-
ble remains in it all belong to species now inhabiting
Kurope.

The depth of the peat indicates that when it was
formed the land stood at a slightly higher elevation than
now, for the base of the stratum is now below the sea-
level, while the peat is of fresh-water origin, and, accord-

ing to Dr. Andrews,* is formed from the vegetable ac- _

cumulations connected with forest growths. When, there-
fore, the. country was covered with forests, as if was in
prehistoric times, the accumulation must have proceeded
with considerable rapidity. This inference is confirmed
by the occurrence in the peat of prostrate trunks of oak,
four feet in diameter, so sound that they were manufact-
ured into furniture. The stumps of trees, especially of
the birch and alder, were also found in considerable num-
ber, standing erect where they grew, sometimes to a height
of three feet. Now, as Dr. Andrews well remarks, it is
evident that, in order to prevent these stumps and pros-
trate trunks from complete decay, the accumulation of
peat must have been rapid. From certain Roman remains
found six feet and more beneath the surface, he estimates
that the accumulation since the Roman occupation has
been as much as six inches a century, at which rate the
whole would take place in somewhat over 5,000 years.
Still, if we accept this estimate, we have obtained but
a starting-point from which to estimate the age of the
high-level gravels in which paleolithic implements were
found; for, if we accept the ordinary theory, we must add
to this the time required for the river to lower its bed
from eighty to a hundred feet, and to carry out to the sea
the contents of its wide trough. But, as already shown,

—— ~ —

* American Journal of Science, October, 1868.

THE DATE OF THE GLACIAL PERIOD. 357

the Glacial period was, even in the north of France, a
time of great precipitation and of a considerable degree of
cold, when ice formed to a much greater extent than now
upon the surface of the Somme. The direct evidence of
this consists in the boulders mingled with the high-level
gravel which are of such size as to require floating ice for
their transportation.

In addition to the natural increase in the eroding
power of the Somme brought about by the increase in its
volume, on account of the greater precipitation in the
Glacial age, there would also be, as Prestwich has well
shown, a great increase in rate through the action of
ground ice, which plays a very important part in the river
erosion of arctic countries, and in all probability did so
during the Glacial period in the valley of the Somme.

“ When the water is reduced to and below 32° Fahr.,
although the rapid motion may prevent freezing on the
surface for a time, any pointed surfaces at the bottom of
the river, such as stones and boulders, will determine (as
is the case with a saturated saline solution) a sort of crys-
tallisation, needles of ice being formed, which gradually
extend from stone to stone and envelop the bodies with
which they are in contact. By this means the whole sur-
face of a gravelly river-bed may become coated with ice,
which, on a change of temperature,-or of atmospheric
pressure, or on acquiring certain dimensions and buoyancy,
rises to the surface, bringing with it the loose materials to
which it adhered. Colonel Jackson remarks, in speaking
of this bottom-ice, that ‘it frequently happens that these
pieces, in rising from the bottom, bring up with them
sand and stones, which are thus transported by the cur-
rent. ... When the thaw sets in the ice, becoming rot-
ten, lets fall the gravel and stones in places far distant
from those whence they came.’

“¢ Again, Baron Wrangell remarks that, ‘in all the more
rapid and rocky streams of this district [northern Siberia]

358 MAN AND TH GLACIAL PERIOD.

the formation of ice takes place in two different manners ;
a thin crust spreads itself along the banks and over the
smaller bays where the current is least rapid; but the
greater part is formed in the bed of the river, in the hol-
lows among the stones, where the weeds give it the appear-
ance of a greenish mud. As soon as a piece of ice of this
kind attains a certain size, it is detached from the ground
and raised to the surface by the greater specific gravity of
the water; these masses, containing a quantity of gravel
and weeds, unite and consolidate, and in a few hours the
river becomes passable in sledges instead of in boats.’
Similar observations have been made in America; but
instances need not be multiplied, as it is a common phe-
nomenon in all arctic countries, and 1s not uncommon on
a small scale even in our latitudes.

“The two causes combined—torrential river-floods and
rafts of ground-ice, together with the rapid wear of the
river cliffs by frost—constituted elements of destruction
and erosion of which our present rivers can give a very
inadequate conception ; and the excavations of the valleys
must have proceeded with a rapidity with which the pres-
ent rate of erosion cannot be compared; and estimates of
time founded on this, ike those before mentioned on sur-
face denudation, are therefore not to be relied upon.” *

Speaking a httle later of taking the present rates of
river erosion as a standard to estimate the chronology of
the Glacial period, the same high authority remarks: “ It
no more affords a true and sufficient guide than it would
be to take the tottering paces and weakened force of an
old man as the measure of what that individual was, and
what he could do, in his robust and active youth. It may
be right to take the effects at present produced by a given
power as the known quantity, a, but it is equally indis-
pensable, in all calculations relative to the degree of those

* Prestwich’s Geology, vol. ii, pp. 471, 472.

Bij

THE DATE OF THE GLACIAL PERIOD. 359

forces in past times, to take notice of the unknown quan-
tity, z, although this, in the absence of actual experience,
which cannot be had, can only be estimated by the results
and by a knowledge of the contemporaneous physical con-
ditions. It may be a complicated equation, but it is not
to be avoided.*

“Tn this country and in the north of France broad val-
leys have been excavated to the depth of from about eighty
toa hundred and fifty feet in glacial and postglacial times.
Difficult as it is by our present experience to conceive this
to have been effected in a comparatively short geological
term, it is equally, and to my mind more, difficult to sup-
pose that man could have existed eighty thousand years
or more, and that existing forms of our fauna and flora
should have survived during two hundred and forty thou-
sand years without modification or change.” +

The discussion of the age of the high-level river gravels
of the Somme and other streams in northwestern Europe
is not complete, however, without considering another
possibility as to the mode of their deposition. The con-
clusion to which Mr. Alfred Tylor arrived, after a pro-
longed and careful study of the subject, was that the main
valleys of the Somme and other streams in northern France
and southern England were preglacial in their origin, and
that the accumulations of gravel at high levels along their
margin were due to enormous floods which characterised
the closing portion of the great ice age, which he denomi-
nated the pluvial period.{ The credibility of floods large
enough to accomplish the results manifest in the valley
of the Somme is supported by reference to a flood which
occurred on the Mulleer River, in India, in 1856, when a

* Prestwich’s Geology, vol. ii, pp. 520, 521.

+ Ibid., p. 533.

¢ Proceedings of the Geological Society, London, November 8,
1867, pp. 105-126; Quarterly Journal of the Geological Society,
February 1, 1869, pp. 57-100.

360 MAN AND THE GLACIAL PERIOD.

stream, which is usually insignificant, was so swollen by a
rainfall of a single day that it rose high enough to sweep
away an iron bridge the bottoms of whose girders were
sixty-five feet above high-water mark. One iron girder
weighing eighty tons was carried two miles down the
river, and nearly buried in sand. ‘The significance of
these facts is enhanced by observing also that for fifteen —
miles above the bridge the fall of the river only averaged
ten feet per mile. Floods to this extent are not uncom-
mon in India. During the Glacial period spring freshets.
must have been greatly increased by the melting of a large
amount of snow and ‘ice which had accumulated during
the winter, and also by the formation of ice-gorges near
the mouths of many of the streams. It is probable, also,
that the accumulation of ice across the northern part of
the German Ocean may have permanently flooded the
streams entering that body of water; for it is by no means
improbable that there was a land connection between
England and France across the Straits of Dover until
after the climax of the Glacial period. In support of his
theory, Mr. Tylor points to the fact “that the gravel in
the valley of the Somme at Amiens is partly derived from
débris brought down by the river Somme and by the two
rivers the Celle and the Arve, and partly consists of ma-
terial from the adjoining higher grounds washed in by
land floods,” and that the “Quaternary gravels of the
Somme are not separated into two divisions by an escarp-
ment of chalk parallel to the river,” but “thin out gradu-
ally as they slope from the high land down to the Somme.”

Mr. T'ylor’s reasoning seems especially cogent to one
who stands on the ground where he can observe the size
of the valley and the diminutive proportions of the present
stream. Even if we do not grant all that is claimed by
Mr. Tylor, it is difficult to resist the main force of his
argument, and to avoid the conclusion that the valley of
the Somme is largely the work of preglacial erosion, and

THE DATE OF THE GLACIAL PERIOD. 361

has been, at any rate, only in slight degree deepened and
enlarged during post-Tertiary time.

SUMMARY.

In briefly summarising our conclusions concerning the
question of man’s antiquity as affected by his known re-
lations to the Glacial period, it is important, first, to re-
mark upon the changes of opinion which have taken place
with respect to geological time within the past generation.
Under the sway of Sir Charles Lyell’s uniformitarian
ideas, geologists felt themselves at liberty to regard geo-
logical time as practically unlimited, and did not hesi-
tate to refer the origin of life upon the globe back to a
period of 500,000,000 years. In the first edition of his
Origin of Species Charles Darwin estimated that the time
required for the erosion of the Wealden deposits in Eng-
land was 306,662,400 years, which he spoke of as “a mere
trifle’ of that at command for establishing his theory of
the origin of species through natural selection. In his
second edition, however, he confesses that his original
statement concerning the length of geological time was
rash ; while in later editions he quietly omitted it.

Meanwhile astronomers and physicists have been grad-
ually setting limits to geological time until they have now
reached conclusions strikingly in contrast with those held
by the mass of English geologists forty years ago. Mr.
George H. Darwin, Professor of Mathematics at Cam-
bridge University, has from a series of intricate calcula-
tions shown that between fifty and one hundred million
years ago the earth was revolving from six to eight times
faster than now, and that the moon then almost touched
the earth, and revolved about it once every three or four
hours. From this proximity of the moon to the earth, it
would result that if the oceans had been then in existence
the tides would have been two hundred times as great as
now, creating a wave six hundred feet in height, which

362 MAN AND THE GLACIAL PERIOD.

would sweep around the world every four hours. Such a
condition of things would evidently be incompatible with
geological life, and geology must limit itself to a period
which is inside of 100,000,000 years. Sir William Thom-
son and Professor Tait, of Great Britain, and Professor
Newcomb, of the United States Naval Observatory, ap-
proaching the question from another point of view, seem
to demonstrate that the radiation of heat from the sun
is diminishing ata rate such that ten or twelve million
years ago it must have been so hot upon the earth’s sur-..
face as to vaporise all the water, and thus render impos-
sible the beginning of geological life until later than that
period. Indeed, they seem to prove by rigorous mathe-
matical calculations that the total amount of heat origi-
nally possessed by the nebula out of which the sun has
been condensed would only be sufficient to keep up the
- present amount of radiation for 18,000,000 years.

The late Dr. Croll, feeling the force of these astro-
nomical conclusions, thought it possible to add sufficiently
to the sun’s heat to extend its rule backwards approxi-
mately 100,000,000 years by the supposition of a col-
lision with it of another moving body of near its own
size. Professor Young and others have thought that pos-
sibly the heat of the sun might have been kept up by the
aid of the impact of asteroids and meteorites for a period
of 30,000,000 years. Mr. Wallace obtains similar fig-
ures by estimating the time required for the deposition of
the stratified rocks open to examination upon the land
surface of the globe. As a result of his estimates, it
would appear that 28,000,000 years is all the time re-
quired for the formation of the geological strata. From
all this it is evident that geologists are much more re-
stricted in their speculations involving time than they
thought themselves to be a half-century ago. Taking as
our standard the medium results attained by Wallace, we
shall find it profitable to see how this time can be por-

THE DATE OF THE GLACIAL PERIOD. 263

tioned out to the geological periods, that we may ascer-
tain how much approximately can be left for the Glacial
epoch. | :

On all hands it is agreed that the geological periods
decrease in length as they approach the present time.
According to Dana’s estimates,* the “ ratio for the Palzo-
zoic, Mesozoic, and Cenozoic periods would be 12:3 :1”—
that is, Cenozoic time is but one sixteenth of the whole.
This embraces the whole of the Tertiary period, during
which placental mammals have been in existence, to-
gether with the post-Tertiary or Glacial period, extend-
ing down to the present time; that is, the time since the
beginning of the Tertiary period and the existence of the
higher animals is considerably less than two million years,
even upon Mr. Wallace’s basis of calculation. But if we
should be compelled to accept the calculations of Sir
Wilham Thomson, Professor Tait, and Professor New-
comb, the Cenozoic period would be reduced to consider-
ably less than one million years. It is difficult to tell how
much of Cenozoic time is to be assigned to the Glacial
period, since there is, in fact, no sharply drawn line be-
tween the two periods. The climax of the Glacial period
represented a condition of things slowly attained by the
changes of level which took place during the latter part
of the Tertiary epoch.

In order to estimate the degree of credibility with
which we may at the outset regard the theory of Mr.
Prestwich and others, that all the phenomena of the Gla-
cial period can be brought within the limits of thirty or
forty thousand years, it is important to fix our minds
upon the significance of the large numbers with which we
are accustomed to multiply and divide geological quanti-
ties. +

* See revised edition of his Geology, p. 586.
+ See Croll’s Climate and Time, chap. xx.

264 MAN AND THE GLACIAL PERIOD.

Few people realise either the rapidity with which geo-
logical changes are now proceeding or the small amount
of change which might produce a Glacial period, and
fewer still have an adequate conception of how long a
period a million years is, and how much present geological
agencies would accomplish in that time. At the present
rate at which erosive agencies are now acting upon the
Alps, their dimensions would be reduced one half in a
million years. At the present rate of the recession of
the Falls of St. Anthony, the whole gorge from St. Louis.
to Minneapolis would have been produced in a million
years. A river lowering its bed a foot in a thousand
years would produce a cafion a thousand feet deep ina
million years.

If we suppose the Glacial period to have been brought
about by an elevation of land in northern America and
northern Europe, proceeding at the rate of three feet a
century, which is that now taking place in some portions
of Scandinavia, this would amount to three thousand feet
in one hundred thousand years, and that is probably all,
and even more than all, which is needed. One hundred
thousand years, therefore, or even less, might easily include
both the slow coming on of the Glacial period and its
rapid close. Prestwich estimates that the ice now float-
ing away from Greenland as icebergs is sufficient if ac-
cumulating on a land surface to extend the borders of a
continental glacier about four hundred and fifty feet a
year, or one mile in twelve vears, one hundred miles in
twelve hundred years, and seven hundred miles (about the
limit of glacial transportation in America) in less than ten
thousand years.

After making all reasonable allowances, therefore,
Prestwich’s conclusion that twenty-five thousand years is
ample time to allow to the reign of the ice of the Glacial
period cannot be regarded as by any means incredible or,
on @ priori grounds, improbable.

AG ie AN, DT UXe-

THE TERTIARY MAN.

By Prorressorn Henry W. Haynes.

“Tr must not be imagined that it is in any way proved
that the Paleolithic man was the first human being that ex-
isted. We must be prepared to wait, however, for further
and better authenticated discoveries before carrying his ex-
istence back in time further than the Pleistocene or post-
Tertiary period.” * This was the position assumed more than
twelve years ago by the eminent English geologist and
archeologist, Dr. John Evans, and it was still maintained in
his address before the Anthropological Section of the British
Association on September 18, 1890. I believe that the study
of all the evidence in favor of the existence of the Tertiary
man that has been brought forward down to the present
time will leave the question in precisely the same state of
uncertainty.

‘Tn order to establish the existence of man at such a re-
mote period the proofs must be convincing. It must be
shown, first, that the objects found are of human workman-
ship ; secondly, that they are really found as stated ; and,
thirdly, the age of the beds in which they are found must be
clearly ascertained and determined.” + These tests I propose
to apply to the evidence for the Tertiary man recently brought

* A Few Words on Tertiary Man, Trans. of Hertfordshire Nat.
Hist. Soc., vol. i, p. 150.
+ Ibid., p. 148.
95 (365)

366 MAN AND THE GLACIAL PERIOD.

forward in Europe, and then to consider the significance of
certain discoveries on the Pacific coast of our own continent.

Tertiary deposits in Kurope are alleged to have supplied
three sorts of evidence of this fact: First, the bones of man
himself ; second, bones of animals showing incisions or
fractures supposed to have been produced by human
agency ; third, chipped flints believed to exhibit marks of
design in their production.

A very complete survey of the question of the antiquity
of man was published in 1883 by M. Gabriel de Mortillet,
one of its most eminent investigators, under the title of Le -
Préhistorique. In that work he subjected to a most rigid
examination all the evidence for Tertiary man, coming un-
der either of these three heads, that had been brought for-
ward up to that date.

The instances of the discovery of human bones in Europe
were two—at Colle del Vento, in Savona, and Castenedolo,
near Brescia, both in Italy. Atthe former site, in a Pliocene
marine deposit abounding in fossil oysters and containing
some scattered bones of fossil mammals,a human skeleton
was found with the bones lying in their natural connection.
Mortillet, however, and many others regard this as an in-
stance of a subsequent interment rather than as proof that
the man lived in Phocene times.* At Castenedolo, in a
similar marine Pliocene formation, on three different occa-
sions human skeletons have been discovered, but in different.
strata. One investigator has accounted for these as the re-
sult of a shipwreck in the Pliocene period. This bold
hypothesis not only requires that man should have been
sufficiently advanced at that very remote period to have
navigated the sea, but it calls for two shipwrecks, at different
times, at the same point. It has, however, since been aban-
doned by its author in favor of the presumption of subse-
quent interments, as in the previous instance. +

* This is also the opinion of Hamy, Précis de Paléontologie Hu-
maine, p. 67. Professor Le Conte, Hlements of Geology (third edi-
tion, 1891), p. 609, is wrong in attributing the opposite conclusion to
Hamy, on the evidence of “ flint implements found in this locality.”

+ Bullettino di Paletnologia Italiana, tome xv, p. 109 (August
18, 1889). .

APPENDIX. 267

Animal bones showing cuts or breaks supposed to be the
work of man have been found in seventeen different locali-
ties in Kurope. They can all, however, be accounted for as
the result of natural movements or pressure of the soil act-
ing in connection with sharp substances, like fractured
flints, or else as having been made by the teeth of sharks,
- whose fossil remains are found in great abundance in the
same formation.

All the discoveries of flints supposed to show traces of
intentional chipping are pronounced to be unsatisfactory,
with the exception of those found in three localities—The-
nay (near Tours) and Puy-Courny (near Aurillac), in
France, and Otta, in the valley of the Tagus, in Portugal.
As European archeologists at the present time are substan-
tially in accord with Mortillet in restricting the discussion
to these three places, I will follow their example. But al-
though Mortillet believes that flints found at all these locali-
ties exhibit marks of intelligent action, he will not admit
that they are the work of man. He attributes them to an
intelligent ancestor of man, whom he calls by the name of
anthropopithecus, or the precursor cf man. Of this creat-
ure he distinguishes three different species, named respect-
ively after the discoverers of the flints in the three localities
just mentioned. The precursor, however, has found up to
this time only a very limited acceptance among men of
science, although a few believe in him on purely theoretical
grounds. The discussion generally turns upon the question
whether these fimts were chipped intentionally or are the
result of natural causes ; and also upon the determination of
the geological age of the formations in which they are found.

I visited Thenay, the most celebrated of these three locali-
ties, in 1877, and had the advantage of studying the question
there under the guidance of the late Abbé Bourgeois, the dis-
coverer of the flints, and one of the most prominent advo-
cates of the Tertiary man. This was the year before he died,
and he showed me at the time his complete collection, and
gave me several of the objects he had discovered. Geolo-
gists are agreed in assigning the deposits in which they
occur to the lower Miocene or middle Tertiary period,
which restricts the discussion to the character of the flints

868 MAN AND THE GLACIAL PERIOD.

themselves. The accompanying woodcut * gives some indica-
tion of their appearance, although it is misleading, because

Fie. 108.—F lint flakes collected by Abbé Bourgeois from Miocene strata
at Thenay (after Gaudry).- Natural size.
the long figure resembling a flint knife is intended to xepre-
sent a solid nucleus. None of these objects, however, ought
to be called “ flints flakes,” as very few, if any, flakes show-

* From Le Conte, op. cit., p. 608. The figures are copied from
Gaudry, who borrowed them from the article by Bourgeois, Congrés
Internat. de Bruxelles, 1872, p. 89, pl. i; and from his La Question
del Homme Tertiare. Revue des Questions Scientifiques, 1877, p. 15.

APPENDIX. 269

ing the “bulb of percussion,” always seen upon them, have
been discovered in the Tertiary deposits at Thenay,* al-
though I have found them there myself wpon the surface.
The three other figures would be classed by archzeologists as
‘“piercers,” as Bourgeois has himself designated them, and
are also solid objects. Many of the Thenay flints exhibit a
“crackled” appearance, due to the action of heat. On
this account Mortillet maintains that they were splintered
by fire, and not formed by percussion, the usual method by
which flint implements were fabricated in the stone age.
The Thenay objects are all of very small dimensions, and
are so absolutely unlike the large, rudely-chipped axes of
the Chellean type, found in so many different parts of the
world, and generally accepted as the implement used by
Paleolithic man, that the question naturally suggests itself,
What could have been the purpose for which these little
implements were employed? No better answer has been
suggested than the ludicrous one that they were used by the
hairy anthropopithecus to rid himself of the vermin with
which he was infested.

But, leaving aside the question of their purpose, let us
consider the evidence presented by the flints themselves.
Do they exhibit the unmistakable traces of intentional chip-
ping produced by a series of slight blows or thrusts, deliv-
ered in regular succession and in the same direction, with
the result of forming a distinctly marked edge? And does
the appearance of the action of fire upon their surface imply
the intervention of intelligence? ‘To both questions M.
Adrien Arcelin, the well-known geologist of Macon, has
given very sufficient replies in the negative. He has discov-
ered numerous objects of precisely similar appearance in
Kocene deposits in the neighborhood of Macon.+ But, in-
stead of pushing man back on this account so much further
into the past, he accounts for the marks of chipping to
be seen on many of these objects as the result of the acciden-
tal shocks of one stone against another in the countless

* Le Préhistorique, p. 91.

+ Matériaux pour l’Histoire Prim. et Nat. de l’ lovin tome xix,
p. 198.

370 MAN AND THE GLACIAL PERIOD.”

overturnings and movements to which the strata have been
subjected during the long ages of geological time. He gives.
photographs of some of these objects, which are to me en-
tirely convincing, and describes how he has surprised Nature
in the very act of fabricating them in an abandoned quarry
worked in an Eocene deposit. He thinks the “crackled ”
surfaces can be readily explained as the result of atmos-
pheric action, or of hot springs charged with silex. Numer-—
ous examples of similar changes in the surface of flint, that
have been noticed by himself and others in different locali-
ties, are instanced. Even if some have been caused by fire,
this does not necessarily imply the intervention of man to
have produced it. Similar discoveries have also been made
by M. d’Ault de Mesnil, at Thenay, in Eocene deposits,* and
by M. Paul Cabanne, in the Gironde.t My own opinion,
based upon the experience of many years spent in the study
of flints broken naturally as well as artificially, and upon a
careful examination of Bourgeois’s collections, is that the so-
called Thenay flints are the result of natural causes.

The second locality where flints alleged to display marks
of human action have been found is the vicinity of Aurillac,
in the Auvergne, especially on the flanks of a hill called
Puy-Courny. They occur in a conglomerate of the upper
Miocene period, and are consequently much later than the
Thenay flints. In this conglomerate, in 1869, M. Tardy dis-
covered a worked flint flake which has every appearance of
being artificial.t Mortillet, however, says that it was found
in the upper surface of the deposit, where there may easily
have been a mingling with the Quaternary formation; and it
certainly resembles worked flakes, which are not uncommon
in the Quaternary. The geological determination of the
find may consequently be regarded as uncertain.

The flints discovered at Puy-Courny by M. Rames are of
small dimensions, and have all been produced by percussion.
Many of them are said to bear some resemblance to pointed

* Matériaux, ibid., p. 246. + Id.. tome xxii, p. 209.

t See Matériaux, tome vi, p. 94. S. Reinach, however, Deserip-
tion Raison. du Musée de Saint-Germain-en-Laye, i, p. 107, n. 8,
ealls it ‘“ gravure inexacte.”

APPENDIX. 371

flakes of artificial origin, and one has been figured, probably
selected for its excellence.* It is by no means convincing to
me, and I am not at all surprised that so many archzologists
question the artificial character of these objects, which ex-
hibit a great variety of forms. Upon this point Rames does
not profess to be qualified to pronounce judgment, limiting
himself solely to the geological questions. He argues, how-
ever, that the fact that all the objects supposed to be arti-
ficial are made of the best qualities of flint, of which imple-
ments are ordinarily made, although fragments of inferior
quality are abundant in the same formation, implies the in-
tervention of man’s judgment in making the selection. But
M. Boule shows that this is merely the result of the erosion
of an ancient river, which operated only upon the upper
beds, in which alone the better qualities of flint are to be
found ; and Rames has accepted this explanation.t The
flints of Puy-Courny seem to fall within the same category
as those of Thenay. They are the product of denudation,
have travelled long distances, and have been subjected to
the action of powerful agents. These causes are sufficient
to account for the shocks of which they show the traces, and
to explain the production of splinters arising therefrom.

The last locality in which flints claimed to have been
manufactured by the Tertiary man are supposed to have
been discovered is the so-called desert of Otta, in the valley
of the Tagus, not far from Lisbon.

The formation there is a lacustrine deposit of great
thickness, belonging to the upper Miocene, and abounding
in flint. Here, during the course of twenty years, M. Ri-
beiro discovered, but mostly upon the surface, a large num-
ber of flakes of flint and quartzite. After much debate in
regard to them, ninety-five of them were finally sent by
him to Paris, in 1878, and placed in the archeological de-
partment of the great exposition. There they were to be
submitted to the judgment of the assembled prehistoric
archeeologists of all nationalities, many of whom, including
the writer, availed themselves of the opportunity of carefully

* Matériaux, tome xviii, p. 400.
+ Revue d’ Anthropologie (third series), tome iv, p. 217.

372 MAN AND THE GLACIAL PERIOD.

studying them. The judgment of Mortillet is that twenty-
two specimens exhibited unmistakable traces of intentional
chipping, in which opinion I entirely concur. Only nine,
however, were represented as coming from the Miocene,
some of which showed on their surface an incrustation of
grit, which was claimed as proof of their origin. But the
opinion was freely expressed that, even if they really came
from the Miocene deposits, they might have penetrated into
them from the surface, through cracks, and thus have be-
come so incrusted. It was accordingly resolved to hold the
next international congress of prehistoric archeologists at
Lisbon, in 1880, mainly for the purpose of settling this ques- —
tion, if possible, by an investigation conducted upon the spot.
In the course of a visit made at that time to Otta, several
artificial specimens were found on the surface by different
searchers, but Professor Bellucci, of Perugia, was fortunate
enough to discover a flint flake in sztu, still so closely im- .
bedded in the deposit that it required to be detached by a
hammer. There is no question that this object was actually
found in a Miocene deposit, but unfortunately it belongs to
the doubtful category of external flakes, which, although
they exhibit the “ bulb of percussion,” have no other sure
indication that they are the work of man.* As such bulbs
can be produced by natural causes, some stronger proof than
this of the existence of Tertiary man is demanded.

These are all the localities in Europe claimed by Mortillet
to have furnished such evidence, but he thinks a strong con-
firmation of it is afforded by certain discoveries made in the .
auriferous gravels of California. I will not occupy space
here in repeating arguments I have brought forward else-
where to show the utter insufficiency of this evidence to
prove the existence of man on the Pacific coast of our conti-
nent during the Pliocene period.t They may ail be summed
up in the words of Le Conte : ‘‘ The doubts in regard to this

* It has been figured by Bellucci, Archivio per ? Anthropologia
ela Etnologia di Firenze, tome xi, p. 12, tay. iv, fig. 2. To me it
possesses no value as evidence.

+ The Prehistoric Archeology of North America, Narrative and
Critical History of America, vol. i, pp. 350-356.

APPENDIX. 373

extreme antiquity of man are of three kinds, viz.: 1. Doubts
as to the Pliocene age of the gravels—they may be early
Quaternary. 2. Doubts as to the authenticity of the finds—
no scientist having seen any of them in situ. 3. Doubts as
to the undisturbed conditions of the gravels, for auriferous
gravels are especially liable to disturbance. The character
of the implements said to have been found gives peculiar
emphasis to this last doubt, for they are not Paleolithic,
but Neolithic.” * The question has been raised whether this
archeological objection is applicable to the stone mortars,
numerous examples of which have been found in the gravels,
some of them quite recently.t If the evidence brought for-
ward by Professor Whitney and others were limited to
these mortars, it might very well be claimed that they are
neither Paleolithic nor Neolithic ; that the smoothness of
their surface is owing to their having been hollowed out of
pebbles that have been polished and worn by natural forces.
But Professor Whitney has cited numberless instances of
““spear-heads,” ‘“arrow-heads,” ‘“discoidal stones,” “stone
beads,” and ‘“‘a hatchet” that have been found under pre-
cisely similar conditions as the mortars. So Mr. Becker has
recently produced an affidavit of a certain Mr. Neale that
in a tunnel run into the gravel in 1877 “between two hun-
dred and three hundred feet beyond the edge of the solid
lava, he saw several spear-heads nearly one foot in length.” {
Now it cannot be questioned that such objects as these clearly
belong to the Neolithic period, which does not imply that all
the objects used at that time were polished, but that together
with chipped implements “ polished stone implements were
also used.” * No archeologist will believe that, while Pa-
leeolithic man has not yet been discovered in the Tertiary
deposits of western Europe, the works of Neolithic man have

* Le Conte, op. cit., p. 614.

+ Professor George Frederick Wright, Prehistoric Man on the
Pacific Coast, Atlantic Monthly, April, 1891, p. 512; Table Mount-
ain Archeology, Nation, May 21, 1891, p. 419.

t Antiquities from under Tuolome Table Mountain in California,
Bulletin of the Geological Society of America, vol. ii, p. 192. !

# Le Conte, op. cit., p. 607.

B74 MAN AND THE GLACIAL PERIOD.

been found in similar deposits in western America. Peculiar
difficulties seem to surround the evidence brought forward
in support of such an assumption. We are told by Professor
Whitney that a stone mortar was “found standing upright,
and the pestle was in it, in its proper place, just as it had
been left by the owner.” He fails, however, to explain how
this was brought about in a gravel deposit supposed to have
been laid down by great floods of water. So, when Mr.
Neale swears that he saw fifteen years ago in the same
gravels spear-heads a great deal larger than those known
to archeologists, may we not ask whether reliance can be ~
placed on the memory of witnesses who testify to impossi-
bilities to justify conclusions that rest upon such testimony ?

I think we shall have to wait for further and better evi-
dence than this before we are called upon to admit that the
existence of the Tertiary man upon our Pacific coast has been
established.

END axe

Aar Glacier, 11, 43, 132.

Abbeville, France, 251, 263.

Abbott, C. C., cited, 242, 245.

Adams, Charles Francis, cited, 297.

Adhemar, cited, 307, 310.

Africa, ancient glaciers of, 191.

Agassiz, Louis, cited, 9, 11, 43, 128,
241,

Ailsa Crag, 167, 168.

Akron, Ohio, 220, 221.

Alaska, 1, 22, 23 e¢ seg., 47, 212, 283 ;
climate of, 291, 302.

Aletsch Glacier, 9, 211, 241.

Alleghany Valley, 206, 214; terraces
in, 229.

Alpine glaciers, existing, 9-11, 43 e¢
seq. ; size and number of, 9 ; depth
of, 11; velocity of, 43 e seq.; an-
cient, 58-60, 131-136; advance and
retreat of, 116.

Alps, 1, 9-11, 43 e¢ seg., 58 et seq., 91,
131 et seg., 211; age of, 328.

Altaville, Cal., 296.

Amazon Valley, temperature of, 316.

Amherst, Ohio, glacial marks near,
52.

Amiens, France, implements from,
252, 263 et seq.; terraces at, 360.

Andes, 17, 330; age of, 328.

Andover, Mass., 77 ef seq., 345.

Andrews, cited, 345, 347, 354, 356.

Animals, extinct, associated with
man in eastern America, 262; in
France, 263; in England, 264 4
seg.; in Wales, 272; in Belgium,
277 et seq.; summary concerning,
281-293.

Animals, relics of, in loess, 188.

Antarctic Continent, existing gla-
ciers of, 1, 18 et seq.

Arcy, Belgium, grotto at, 279.

Arenig Mawr, Wales, 150, 151, 172.

Argillite implement, face and side
view of, 247, 259.

Arnhem, Holland, moraine at, 181.

Asia, existing glaciers in, 14 eé¢ seg. ;
ancient glaciers of, 190.

Assiniboine River, 228.

Astronomical theories of the Glacial
period, 303 e seq.

Atlantic Ocean, 314.

Aurillac, supposed flint-chips near,
367, 370.

Australia, ancient glaciers of, 126,
192.

Austria, existing glaciers of, 9.

Auvergne, 136.

Bakewell on age of Niagara gorge,
337.

Baldwin, C. C., 251.

Baldwin, P., 25.

Ball, cited, 310, 317.

Baltic Sea, 129.

Barnsley, England, 155.

Bates, cited, 204.

Bear, 270, 287, 290.

Bear, grizzly, 270, 288.

Beaver, 289.

Beaver Creek, Pa., 205, 230, 232.

Becker, cited, 296, 800, 349.

Bedford, England, 265.

Beech Flats, Ohio, terrace at, 217.
Belgium, human relics in glacial
terraces in, 264; caverns of, 274.
Bell, cited, 109, 117 ; on unity of the

Glacial period, 110.

Bellevue, Pa., glacial terrace on the

Ohio at, 217.
Bellucci, cited, 372.
Ben Nevis, 240.
Bernese Oberland, 9, 59, 131, 132.
Big Stone Lake, 208, 226.
Birmingham, England, 150.
Bishop, cited, 306.
Bison, 262, 270, 271, 278, 289.

(875)

—

316
Black Forest, the, 136.
Black River, Ohio, 343.
Black Sea, 238.
Blane, Mont, 1, 9-11, 1
Blandford, cited, 312.
Boone County, Ky., glacial deposits
in, 212.
Boston, scratched stone from till of,
54; drumlins in the vicinity of, 75.
Boston Society of Natural History,
296.
Boulder-clay. (See Trt.)
Boulders, disintegrated, 57, 71.
Boulders, distribution of, in New
England, 57, 60, 61, 69 e¢ seg.; in
Switzerland, 58 e¢ seq., 133.
Boulders, transportation of, in Penn-
sylvania, 57, 61, 85; in New Hamp-
shire, 60, 71; in Kentucky, 63, 97;

XC
32,

211.

MAN AND THE GLACIAL

in Ohio, 64,72; in Rhode Island, |

67; 1n Massachusetts, 69 e¢ seq. ;
in Connecticut, 71, 72; in New
Jersey, 83; in Illinois, 97.
Bourgeois, Abbé, cited, 367.
Bridgenorth, England, 150.
Bridlington, England, 156, 158.
Bristol Channel, 138, 178.
British Columbia, 1, 23, 121 e¢ seq.,
194, 198.
British Isles, ancient glaciers of, 136—
181; preglacial level of land in,
139-141; preglacial climate in 141,
142; great glacial centres— Wales,
143; Ireland, 143; Galloway, 144;

144; confluent glaciers—Irish Sea |
Glacier, 145-153; Solway Glacier,

153-158; East Anglian Glacier,
158; Isle of Man, 164-167; the so-
ealled Great Submergence, 167-
180; dispersion of erratics of Shap
granite, 180,181; drainage of, 238 ;
caverns of, 267; climate of, 314.
Brixham Cave, 267 e seq.
Bromsgrove, England, 150.
Brooklyn, N. Y., 66, 67.
Brown, on glaciers of Greenland, 40,
41,
Brown’s Valley, 226.
Bruce, skull of, 276.
Buried forests in America, 107 et seq.
Buried outlets and channels, 199-
210 Otscake Brie 20ine S33emor
Lake Huron, 202; of Lake Onta-
rio, 202; of Lake Superior, 203; of
Lake Michigan, 203; m_ south-
western Ohio, 203; near Cincin-
nati, 203; near Louisville, Ky.,
205; in the Tuscarawas Valley,
205; in the valley ot the Beaver,

PERIOD.

205; of Oil Creek, 205; in the
valley of the Alleghany, 206; of
Chautauqua Lake, 207; near Min-
neapolis, 208.

| Burton, England
Busk, cited, 267.
Buttermere, England, 153, 168.

, 164.

Cache Valley, Utah, 233.

Cae Gwyn Cave, 148, 271 e¢ seq., 280.

Caithness, Scotland, 180.

Calaveras skull, 295, 300.

California, 21, 124, 281, 287, 294, 358,
372.

Cambridgeshire, England, 158.

Canada, 94, 95.

Canstadt, man of, 279.

Canton, Ohio, 232.

Cape St. Roque, 313.

Caribbean Sea, 318.

Caribou, 262.

Carll, cited, 205, 207. -

Carpathian Mountains, 136, 328.

Carpenter, F. R., cited, 321, 322.

Cascade Range, 21.

Caspian Sea, 238.

Cattaraugus Creek, N. Y., 220.

Caucasus Mountains, 15; age of, 328.

Cave-bear, 269-271, 278, 280; hyena,
269, 270, 278; lion, 269-271, 278.

Caverns, British, 267-274; on the
Continent, 274-281.

Cefn Cave, 148, 271.

Cenis, Mont, 135.

Lake District, 144; Pennine Chain, | Centres of glacial dispersion, 304 e¢

seéq., 823 et seqg., 328; in America,
1138, 121; in Europe, 129 e seg.; in
the British Isles, 142 7 seq.

Cevennes, 136.

Chamberlin, T. C., terminal moraine
of second Glacial epoch, 93, 98 e
seg.; on driftless area, 102, 103;
cited, 110, 218, 229, 307; on Cin=
cinnati 1ce-dam, 215.

Chamois, 289, 290.

Chamouni, 132.

Charpentier, 9, 59.

Chasseron, 58, 152.

Chautauqua Lake, buried outlet of,
207.

Chenango River, 220.

Cheshire, England, 149, 153, 178, 180.

Cheyenne River, 228.

Chicago, II1., 346.

Chimpanzee, skull of, 276.

Chur, 133.

Cincinnati, buried channels near,
203 e€ seg.; glacial dam at, 212 @
seq. terraces at, 231.

Clarksburg, W. Va., 216.

INDEX.

Claymont, Del., 258 e¢ seq.; view of
implement found near, 259.

Claypole, cited, 200, 219, 221.

Climate of Glacial period, 291.

Clwyd, vale of, 147 e¢ seq., 271 et seq. |

Clyde, the, 144.

Collett, cited, 107.

Colorado, 123, 124.

Columbia deposit, 245, 254 e¢ seq.

Columbiana County, Ohio, 232.

Comstock, cited, 307.

Conewango Creek,
depth of, 206.

Connecticut, 71, 72, 74, 91.

Conyers, cited, 265.

Cook on subsidence in New Jersey,
196.

Cope, cited, 288.

Cordilleran Glacier, 121 ¢# seq.

Corswall, England, 312.

Cows, 268.

Cresson, cited, 251, 258 ct seq.

Crevasses. (See Fissures.)

Croll, cited, 304, 307 ef seq. 3 332, 362.

Cro Magnon, rock shelter of, 281.

Cromer, England, 160.

Crosby, on composition of till, 81 é
seq.

Crocs Fell escarpment, 153, 180.

Culoz, 132.

Cumberland, England, 146, 153, 168,
SG

Cumming, quoted, 166.

Cushing, H., 26

Cuyahoga River, 220, 221; buried
channel of, 200.

232; ancient

Dana, Professor J. D., on depth of
ice, 91; on driftless area, 102;
cited, 320, 363.

Danube, ancient glaciers of the, 129,
134 188.

Darent, valley of, 265.

Darrtown, Ohio, 107.

Darwin, Charles, cited, 17, 126, 170,
241, 361.

Darwin, George G., cited, 361. |

Darwin, Mrs. M. J., mortar owned
by, 297.

Date of Glacial period, chapter on,
332-364,

Davidson Glacier, 23.

Davis on drumlins, 75.

Dawkins, cited, 238, 267, 269, 291.

Dawson, G. M., cited, 121; on ice-
movements, 97; on oscillation of
land-level, 125, 126.

Dawson, Sir William, on the fiord of
the Saguenay, 197; cited, 285.

Dee, the river, 149.

Deeley, quoted, 164.

Delaware River, 232, 242 et seq., 254,
258 5 section across the, 245.

Delta terrace at Trenton, N. J., 242
et seq.; at Beaver, Pa., 230.

De Rance, cited, 272.

Derbyshire, England, 270.

Desor on age of Niagara gorge, 337.

Diore, glaciers of the, 135.

Disintegration, amount of, near gla-
cial margin, 117, 118.

Diss, England, 266.

Dnieper, the, 185, 188.

Don, the, 185, 188.

Dora Baltea, 134.

Dover, N. H., section of kame near,
Uh

Dover, Straits of, 238.

Drave, glaciers in the, 134.

Drainage systems in the Glacial
period, 335, 339, 340, 343, 344 ; chap-
ter on, 193-241.

Drayson, cited, 317.

Driftlesss area in the Mississippi
Valley, 101, 102.

Drunlins, description of, 73 et seq. ;
view of, 73; occurrence of, in Mas-
sachusetts,73 ; in New Hampshire,
74; in Connecticut, 74, in New
York, 74, 94; in the British Isles,
74, 187, 167.

Dunbar, Scotland, 312.

Dupont, cited, 279.

Du Quoin, Ill., 98, 119.

D’Urville, 20.

Disseldortf, 275.

Eagle, Wis., view of kettle-moraine
near, 99.

East Anglian Glacier, 158-164.

Eccentricity of the earth’s orbit, 308.

Eden Valley, 180.

Eggischorn, 211, 241.

Eguisheim, skull found at, 279.

Elephant, 265, 280, 282, 283, 292.

Elevation, preglacial, 112, 194, 198 ;
the cause of the Glacial period,
113, 320-331; about the Great
Lakes, 224; in the latitude of New
York, 261.

Elyria, Ohio, 342.

Engis skull, view of, 274.

England. (See Bririsu Ises.)

Enville, England, 150.

Erosion, preglacial, 198 e seq.

Erosion in river valleys, 198,
oD2.

Erzgebirge, 136, 181.

Europe, existing glaciers in, 9 ef seq.,
43 et seqg.; ancient glaciers of, 129-

329,

318

190; former elevation of, 238; ice-
dams in, 360.
Evans, cited, 263, 267, 354, 365.

Falconer, cited, 263.

Falls of St Anthony, 209.

Faudel, cited, 279.

Fiesch, Switzerland, 13

Filey Brigg, Eng., 155.

Finchley, Eng., 158, 159.

Finger Lakes, 94.

Finsteraarhorn, 9.

Fiords, 194 e¢ seqg.; of Greenland, 212.

Fissures in glacial ice, 3, 48, 49.

Flamborough, 140, 156, 157, 176.

Florida, 314.

Flower, cited, 263.

Forbes, 9, 38, 43, 44, 48.

Forel, M., cited, 116.

Fort Snelling, Mississippi gorge at,
208, 340 et seq.

Fort Wayne, Ind., 220, 224.

Foshay, cited, 119.

Fox, 270, 289, 290.

Fraipont, cited, 275 et seq.

France, existing glaciers of, 19; an-
cient glaciers of, 1386; glacial
gravels of, 262 et seq.

Frankley Hill, England, 150.

Franklin, Pa., 230, 232.

Franz-Josef Land, 14.

Frederickshaab Glacier, 91, 212.

Frere, cited, 266.

Frickthal, 133.

Frondeg, Wales, 149, 178.

, 21.

Gabb, cited, 318.

Galloway, ancient glaciers of, 144,
145, 154, 157, 167, 168, 173.

Garda, Lake, moraine in front of,
135.

Garonne, the, 136, 188.

Gaudry, cited, 263.

Geikie, Archibald, cited, 272 319.

Geikie, James, on kames, 76; on
loess, 187, 188; cited, 291 e¢ seg.,
307, 353.

Genesee River, 220.

Geological time, 361 et seq.

Georgian Bay, 339.

German Ocean, 129.

Germantown, Ohio, 107, 108.

Germany, North, moraine in, 181,
183; glacial lakes in, 238; Qua-
ternary animals in, 279.

Gietroz Glacier, 211.

Gilbert, cited, 233 et seq., 350 et seq.;
on age of Niagara gorge, 339.

Glacial dispersion. (See CENTRES OF
GLAcIAL DispErsion.)

MAN AND THE GLACIAL PERIOD.

Glacial boundary in New England,
67; in New Jersey, 83; in Penn-
sylvania, 84 e¢ seg.; in New York,
84; in Ohio, 95, 100, 106; in Ken-
tucky, 96; in Indiana, 96; in Ili-
nois, 96, 100; in Kansas, Nebraska,
Missouri, Montana, South Dakota,
96; in Minnesota, 101; in British
Isles, 187, 148, 150, 151, 155, 167;
in Holland, 181; in Germany, 181,
183; in Russia, 181, 189.

Glacial erosion, 118, 119, 182.

Glacial ice, depth of, in Pennsyl-
vania, 90 et seg.; in Connectient,
91; in New York. 91; in Green-
land, 91; in the Alps, 91, 131, 138,
182; in Germany, 182; in Norway,
182; amount of, 330.

Glacial lakes in Germany, 283.
Glacial motion, limit of, 2; chapter
on, 43-50; plastic theory of, 48.
Glacial outlets of the Great Lakes,

220-222.

Glacial periods, cause of, 113; chap-
ter on, 302-331; date of, chapter
on, 332-364.

Glacial periods, supposed succession
of, 106 et seg., 311, 324-326, 332;
criticisms of the theory, 116 eé seg.

Glacial strie. (See Rock-Scortne.)

Glacial terraces, 229-238; in Penn-
sylvania, 87 et seq., 215, 217, 229,
230; in New York, 88; at Beech
Flats, Ohio, 217; at Granville,
Ohio, 227 ; on the Minnesota River,
228; around Great Salt Lake, 233
et seq.; on Delaware River, 243 ef
seq.; in Europe, 238-241; in Ohio,
249 et a human relics in, 241-
267; on Delaware River, 245; of
the Mississippi River, 254; in
France, 263 e seq., 360; in Eng-
land, 264 e¢ seq.;in Belgium, 264;
in Spain, 264; in Portugal, 264; in
Italy, 264; in Greece, 264.

Glacial theory, crucial tests of, 62,
65, 257, 802 et seq.

Glaciation, signs of past, chapter on,
51 et seq.

Glacier Bay, 24; map of, 25.

Glacier, defined, 2; formation of, 3;
characterised by veins and fissures,
8; advance and retreat of, 116;
velocity of, in the Alps, 48 é seq.,
in Greenland, 36, 46-48 ; in Alaska,
47,

Glaciers, ancient, in North America,
66-128 ; in Central and Northern
Europe, 58-60, 131-136; in the
British Isles, 136-181 ; in Northern

INDEX. © 379

Europe, 181-190; in Australia, 126,
192; in Asia, 190, 191; in Africa,
191, 192.

Glaciers, existing, in the Alps, 9 e7
seg., 48 et seqg.; in Scandinavia,
12; in Spitzbergen, Nova Zembla,
and Franz-Josef Land, 12; in Ice-
land, 14; in Asia, 14 e¢ seq.; in
Oceanica, 16; in South America,
17; in Antarctic Continent, 18 e
seg.; in North America, 20 ¢é seq. ;
in Greenland, 32 e seq., 46, 48, 364.

Glen Roy, parallel roads of, 239.

Glutton, 293.

Goat, 268.

Gottstown, N. H., 73.

Grafton, W. Va., 214.

Grand Haven, Mich., 346.

Granville, Ohio, terrace at, 227, 343.

Grape Creek, Col., view of moraines
of, 123.

' Great Bend, Pa., depth of river-
channel at, 206.

Great Lakes, depth of, 115; forma-
tion of, 199 e¢ seg.; glacial outlets
of, 220-222; elevation about, 224.

Great Salt Lake, Utah, 233 ¢ seq.,
350,

Greece, human relics in glacial ter-
races of, 264.

Greenland, existing glaciers of, 1,
32 et seq., 46, 48, 364; map of, 33 ;
climate of, 302.

Gross Glockner, 9, 134.

Ground ice, 357.

Gulf of Mexico, 313, 318.

Gulf Stream, 13, 311, 313, 317 e¢ seg.

Guy ot, 9, 58, 133.

Haas, 16.

Hall, on the age of Niagara, 336.

Hare, 289.

Harrison, quoted, 167.

Harte, Bret, cited, 296.

Hartz Mountains, 136, 181.

Hayes, 36.

Haynes on Tertiary Man, 365-374.

Tleald Moor, England, 147.

Hebrides, the, 136.

Heim, 9.

Helland, 14, 46-48.

Hennepin, cited, 340.

Herne Bay, England, 265.

Herschel, cited, 310.

Hertfordshire, England, 158.

Hicks, Dr. H., cited, 272.

Hicks, L. E., cited, 348.

Himalayas, 1,45, 292, 330; age of, 328.

Hingham, Mass., section of kame
near, 79.

Hippopotamus, 263, 265, 271, 280,
284, 285, 290, 292.

Hitchcock, C. H., discovery of
boulders on Mount Washington,
60; on drumlins, 73; cited, 309,
315.

Hitcheock, E., on kames, 77.

Holland, terminal moraine in, 181.

Holderness, 157.

Hooker, cited, 191.

Horse, 188, 263, 268-270, 272, 278,
280, 288, 289.

Horseheads, N. Y., 220.

Horseshoe Fall, 337 e€ seq.

Hottentot skull, 276.

Hoxney, England, 266.

Hudson River, preglacial channel of,
194 e seq.

Hugi, 9, 43.

Hungary, Quaternary animals in,
ATS)

Huxley, cited, 276, 278.

Hyena, 271, 272, 282, 291, 292.

Tbex, 289.

Icebergs, 18, 20; formation of, 28.

Ice, characteristics of, 2, 48 e seq.,
302 et seqg.; transporting power of
moving, 5.

Ice-dams, 211-228; in the Alps, 211;
in the Himalayas, 211; in Green-
land, 212; in Alaska, 212; at Cin-
cinnati, 213 e¢ seg.; across the Mo-
hawk, 92, 220, 334, 335: in the Red
River of the North, 225; in Eu-
rope, 360.

Iceland, existing
14.

Ice-pillars, 6, 27.

Ice-sheet, retreat of, 333 ef seq.

Idaho, 122; lava-beds of, 297.

Tlhicilliwaet Glacier, 23.

Ilinois, 96-98, 100, 119, 121, 345 et
Seq.

Indiana, 96, 98, 107, 119, 121

Indian Ridge, 80.

Towa, 98, 101.

Ireland, ancient glaciers of, 143.

Irish elk, 270, 278, 288.

Trish Sea Glacier, 137, 145-153, 164,
271.

Irthing, valley of the, 153.

Isere, glaciers of the, 132.

Isle of Man, 164-167.

Isle of Wight, 266.

Italy, existing glaciers of, 9; ancient
glaciers of, 135; human relies in
glacial terraces of, 264; supposed
Tertiary man in, 366.

Ivrea, 154.

glaciers of, 1,

380 MAN AND THE GLACIAL PERIOD.

Jackson, cited, 357.

Jackson’s Lake, 123.

Jakobshavn Glacier, velocity of, 46,
47; depth of, 91; ice-dams of, 212.

James, cited, 204.

James River, Dak., 228.

James River, Va., 257.

Jamieson, cited, 330.

Jensen, 91.

Judge’s Cave, 72.

Jura Mountains, ancient glaciers of,
58-60, 132.

Kames, formation of, 7, 76, 77; of
Muir Glacier, 29, 30; in Massachu-
setts, 77 e¢ seg.: in New Hamp-
shire, 80; map of, in Maine, 81;
in Pennsylvania, 87.

Kanawha hiver, 216.

Kane, 36-38.

Kansas, 96.

Kelly’s Island, view of grooves on,
103, 105.

Kendall, chapter by, 137-181; cited,
278.

Kent, England, 265.

Kent’s Hole, 267 et seq., 352 et seq.

Kentucky, 63, 96, 97, 212; view of
boulder in, 63. ;

Kentucky River, 214.

Kettle-holes, formation of, 7, 68; of
Muir Glacier, 29, 30; in New Eng-
land, 66 et seg., 344, 346; in Penn-
sylvania, §6; sedimentation of,
339, 344 et seq.

Kettle-moraine in Wisconsin, 100.

King, 21, 351; implement discov-
ered syn. 20%

Knox County, Ohio, 232.

Kurtz, Nampa image discovered by,
297.

Lake Agassiz, 126, 223, 225; con-
tinuance of, 347 et seq.

Lake Bonneville, 233 e¢ seq., 299, 350
éf Seq.

Lake Constance, 60, 133.

Lake Erie, origin of, 200 e seg. ;
ridges around, 222; preglacial out-
let of, 200, 333.

Lake Geneva during the Glacial pe-
riod, 131, 132.

Lake Huron, preglacial outlet of,
202, ridges around, 224.

Lake Itasca, 254.

Lake Lahontan, 233, 234.

Lake Michigan, age of, 345 et seq.

Lake Nipissing, 339.

Lake Ontario, origin of, 201 e¢ seq.

Lake Traverse, 208, 226.

Lake District, England, the, 144.
Lake dwellings in Switzerland, 281.
Lake ridges, 222 et seq.

Lakes, sedimentation of, 333, 344 et
seq.

Lamplugh, glacial observations of,
140, 196.

Laneashire, 153, 178, 180.

Lancaster, Ohio, 232.

Lang, cited, 116.

Lark, England, valley of the, 266.

Lateral moraines, 5.

Laurentide Glacier, 113 e¢ seg., 121,
O21.

Lava on the Pacific coast of North

_ America, 294, 298, 300, 306, 321.

Lawrenee, Mass., 80.

Lawrenceburg, Ind., 231, 232.

Le Conte, cited, 286, 322 e seq., 330,
Be hoe

Leicestershire, England, 158.

Lehigh River, 243.

Lemming, 289.

Lenticular hills, 73.

Leopard, 282.

Lesley, cited, 215.

Lesse, Belgium, valley of the, 279.

Leverett, cited, 101, 218.

Lewis, on transported boulders, 57,
61; work of, in Pennsylvania, 84,
119; in Great Britain, 137; cited,
254 et seq., 273.

Lickey Hills, 151.

Licking River, 214.

Liege, Belgium, 274.

Lincolnshire, England, 158.

Lindenkohl on old channel of the
Hudson, 195 e¢ seq.

Lion, 282, 293.

Little Beaver Creek, 231, 232.

Little Falls, Minn., 225, 232, 252,
204. zt

Little Falls, N. Y., buried channel
near, 202. .

Livingston, Mont., 122.

Llangollen, vale of, 151.

Loess in the Mississippi Valley, 98,
119, 120; in Europe, 186 e seq.

Lohest, cited, 275 e¢ seq.

Lombardy, 134.

London, 158, 159, 178; glacial ter-
race in, 264.

Long Island, 66, 67.

Louisville, Ky., buried channel near,
205.

Loveland, Ohio, 232, 250.

Lubbock, cited, 267.

Lucerne, 133.

Lyell, on Richmond train of boul-
ders, 70; cited, 239, 263, 267, 274,

-—~

IN DEX.

B81

276, 285, 355, 361; on the age of ; Minneapolis, 232; buried outlet near,

Niagara, 336.
Lyons, 132.

Maack, cited, 318.

Macclesfield, England, 273.

MacEnery, cited, 267.

Machairodus, 270, 282.

Mackintosh, quoted, 149, 150, 173.

Macon, France, 369.

MeTarnahan, mortar discovered by,
297.

Madison boulder, 71.

Madisonville, Ohio, 232, 250, 254.

Magdalena Bay, 13.

Mahoning River, 220.

Maine, 80; re-elevation of, 331.

Malaspina Glacier, map of, 31.

Mammoth, 188, 190, 263, 265, 269-
272, 278, 280, 283-285, 287, 292, 293.

Man, relics of, in the Glacial period,
chapter on, 242-301; in glacial!
terraces of the United States, 242-
262; of Europe, 262-267 ; in cave
deposits of British Isles, 148, 267-
274; of the Continent, 274-281;
under lava-beds of the Pacific
coast of North America, 294-301;
extinct animals associated with,
281-293.

Manitoba, 97.

Mankato, Minn., 229.

Marcilly, skull at, 279.

Marietta, Ohio, 231.

Marmot, 289, 293.

Marsh Creek Valley, Utah, 233.

Martigny, ancient glaciers near, 59,
60, 131, 211.

Massachusetts, 67 et seq., 738, 77 et
seq., 81, 344, 345.

Mastodon, 262, 278, 285, 286.

Mattmark See, 211.

Maumee River, 220.

McGee, cited, 245, 254 et seg.

Medial moraines, formation of, 6;
of Muir Glacier, 27; in Ohio, 100.

Medlicott, cited, 312.

Medora, Ind., 232, 251, 254.

Menai Straits, 145.

Mentone, skeleton of, 281.

Mer de Glace, 11, 44.

Merjelen See, 211, 241.

Mersey, the, 140.

Meteorites, 305.

Metz, cited, 250.

Meuse, valley of, 274 et seq.

Miami, the Great, 204, 220.

Miami, the Little, 231, 250.

Millersburg, Ohio, 232.

Mills, cited, 251.

26

. 208; recession of falls at, 210, 340
et séq., 304.

Minnehaha, Falls of, 342.

Minnesota, 101, 107, 252 & seq.; lakes
of, 344.

Minnesota River, a glacial outlet,
208, 225, 228, 342.

Miocene epoch, animals of the, 285.

Mississippi River, gorge of, at Fort
Snelling, 208, 364; terraces on, 229 ;

| erosion by, 329; glacial drainage
of, 335, 340.

Missouri Coteau, 101, 126, 228.

Missouri, 96, 98, 119.

Moel Tryfaen, 145, 167 e€ seqg., 178,
273.

Mohawk River, glacial drainage of,
92, 202, 335; ice-dam across, 220,
334, 385.

Mohegan Rock, 71; view of, 72.

Monongahela River, 214 é seq.

Montaigle, valley of the, 279.

Montana, 96.

Montreal, re-elevation of, 331.

Moose, 262.

Moraines, formation of, 6; in Wis-
consin, 98-100; in Italy, 134, 135;
between Speeton and Flambor-
ough, 156: in Germany, 183.

Morecambe Bay, 146, 180.

Morgantown, W. Va., 215.

Morlot, cited, 354.

Mortillet, cited, 366, 369, 372.

Morvan, the, 136.

Moulins, formation of, 7.

Mount Shasta, 21.

Mount Washington, 61.

Mueller Glacier, 17.

Muir Glacier, 24 et seq., 47, 68, 212;
view of front of, 26.

Muir, John, 24.

Muskingum River, 220, 231.

Musk ox, 262, 280.

Musk sheep, 289, 290, 293.

Nampa image, 297 ef seq.

Nansen, 39, 41.

Naulette, jaw found at, 278, 279.
Neale, implements discovered by,
296, 373.

| Neanderthal skull, 275 e¢ seg.

| Nebraska, 96.

Nelson River, 349.
Neufchatel, 133.
Nevada, 124; lakes of, 233.
Névé-field defined, 3.
Newark, Ohio, 232.
| Newberry on the preglacial drainage
| of the Hudson, 195 e¢ seg.; on the

382 MAN AND THE GLACIAL PERIOD.

formation of the Great Lakes, 202 | Pennsylvania, 57, 61, 84 e¢ seg., 119,

et seg.; cited, 320. 217.
Newburg, N. Y., 286. Perry County, Ohio, 232.
New Comerstown, implement from, | Perthes, Boucher de, 262 et seq.
232, 250, 251 et seq., 254. Philadelphia Academy of Sciences,
New "England, 57, 60, 61, 91; an- 296.
cient glaciers in, 66-83. Philadelphia, red gravel of, 254 e¢
New Hampshire, 69, 71, 74, 80. Seq.
New Harmony, Ind., 232. Phillips, cited, 267.
New Jersey, 83. Picardy, glacial gravels of, 262.
New Lisbon, Ohio, 232. Pittsburg, Pa., submergence of, 214,
New York, 74, 84, 88, 91, 92 e¢ seq. 217, 230,
New York Bay, 184, 197, 249. ' Plum Creek, Ohio, 344.
New Zealand, 1, 126, 192, 330. Po, valley of the, 135; erosion by,
Niagara gorge, "age “of, 333. et SEQ. § 328.
section of strata along the, 336. Pocatello, Idaho, 236, 299.
Nile River, 285. Pocono Mountain, 61.
Nordenskiéld, 32, 34. Poland, 181.
Norfolk, England, 161. Polynesian skull, 276.
North Ameri ica, existing glaciers in, | Pomp’s Pond, section of kettle-hole
20 et seq. near, 340. .
North Sea, 238. Portageville, INS Yo 220:
Norway, climate of, 314. | Port Neuf River, Idaho, 236.
Nottingham, England, 164. Portsmouth, Ohio, 231.
Nova Zembla, 14, Portugal, human relics in glacial
Nunataks, 27, "32. terraces of. 264; supposed Ter-
tiary man in, 367, 371 e€ seg.
Oberlin, Ohio, 64, 344. Post-glacial erosion, 332 et seg.; in
Oceanica, existing glaciers of, 16, 17. Ohio, 343, 344; in Illinois, 345 e
Ohio River, clacial terrace, 217, 229, seq.

Ohio, 64,72, 05, 98, 100, 103, 106, 107- | Potomac River, 256 et seq.
117, 119, 217, 249 e¢ seg., 343, 344, | Pot-holes in Lucerne, 133.

Oil Creek, 205, 232. Pouchet, cited, 263.
Olmo, skull at, 279. Precession of equinoxes, 308.
Oregon, 21, 124. Preglacial climate in England, 141,
Orme’s Head, Little, 147. 142.
Orton, cited, 72, 107. Preglacial levels in England, 129-
Oscillations ate land-level in Amer- 142.

ica, 124 et se Prestwich, cited, 186, 189, 263 eé
Osw estry. Bieland, 173. Seq. 284: on date of Glacial period,
Ottawa River, 339. | 3854, 357, 363, 364.
Otter, 290. | Provo shore-line, 237.
Ouse, valley of the, 265. Putnam, cited, 250.
Ox, 269, 270. Puy-Courny, France, supposed Ter-

tiary man at, 367, 3870, 371.
| Pyramid Lake, 350,

Pacific coast of America, 349.

Pacific Ocean, 318, 320. | Pyrenees, glaciers of the, 11, 136;
Panama, Isthmus of, 113, 313, 314,318. Quaternary animals of, 280, 282°;
Parsimony, law of, VW17. age of, 328.

Pasterzen Glacier, 134,

Patagonia, 1. Quaternary animals of California,
Patton, 25, 281, 287; in Germany, 279; im
Payer, 14, 39. Hungary, 279.

Peat-beds, 68, 125; in Ohio, 107 ; Quatrefages, cited, 276.

Minnesota, 108; in valley of ‘ie Queenston, Canada, 333 et seq.
Somme, 355 et 89.

Pembina River, 998) Rabbit, 289. ,
Pengelly, cited, ¢ 267, 2 Raccoon Cr eek, 343; view of glacial
Pennine Chain, ieee of, 137, terrace near, "9977.

144, 146, 147, 154, mare Rames, cited, 370, Bee

INDEX.

Ramsay, cited, 311.

Rappahannock River, 257.

Rawhide Gulch, Cal., 296.

Recession, rate of, of Falls of Ni-
agara, 333 et seg.; of Falls of St.
Anthony, 340 e seq., 364; of Black
River, 342, 343.

Red deer, 263.

Red River of the North, 209, 228,
340; ice-dam in, 225.

Regillout, 263.

Reid, Clement, quoted, 162.

Reid, H. F., 26, 47.

Reindeer, 188, 262, 268, 269, 270, 278,
280, 287, 290, 293.

Rhine, ancient glaciers of the, 129,133.

Rhinoceros, 188, 268, 265, 271, 277,
278, 280, 284, 286, 287, 292; woolly,
269, 270, 272, 280, 287.

Rhode Island, 67.

Rhone, ancient glaciers of, 58-60,
131,132, 185, 188; map of, 58.

Richmond, Mass., train of boulders
ae KOs afelis

Rink, Dr., 35.

Roanoke River, 257.

Rocky Mountains, 320, 322; age of
the, 328.

Rock-scorings, cause of, 51 et seq. ;
in New England, 69; on islands
of Lake Erie, 103, 104; in Pennsyl-
vania, 119; in Ohio, 103, 119; in
Indiana, 119; in Illinois, 119;
in Missouri, 119.

Roman remains, 356.

Rome, N. Y., 335.

Rosa, Mount, 9, 134, 211.

Ross, Sir J. C., 18, 19, 311.

Royston, England, 155.

Runaway Pond, 207.

Russell, I. C., exploration of Mount
St. Elias by, 30, 212; cited, 233,
300 et seq.

Russia, glacial boundary in, 181, 189 ;
glacial drainage of, 238.

Saguenay, fiord of the, 197.

Salamanea, N. Y., buried channels
near, 206.

Salisbury, cited, 183, 184.

Salt Lake City, 123.

Sandusky, Ohio, section of the lake
ridges near, 223.

Sandusky River, 220.

Sanford, cited, 267.

Saskatchewan River, 228.

Saxony, 181.

Scandinavia, existing glaciers of, 2,
12; ancient glaciers of, 129, 136,
157, 181-190: re-elevation of, 331.

383

Scioto River, 231.

Seotland. (See Britisu Isizs.)

Seattle, section of till in, 55.

Second Glacial period, 106 & seq.

Section, ideal, across river bed in
drift region, 229.

Sedimentation of lakes, 333.

Seine, terraces of the, 186, 188, 264.

Seracs, 4, 5.

Settle, England, 270.

Severn, the, 149-151, 285.

Shaler, 67, 242.

Shap granite, 154, 157, 180.

Ship Rock, 71.

Shone, cited, 180.

Shoshone Falls, 299.

Shrewsbury, England, 150.

Shropshire, England, 149, 173.

Siberia, 190; Quaternary animals in,
280, 282, 283, 290; climate of, 302,
316.

Sierra Nevada Mountains, 21, 294,
301, 820, 322, 849, 352.

Skertchly, qucted, 159.

Skipton, 144, 146.

Skull, comparative study of, 276.

Slickenside, 53.

Smock on depth of glacial ice, 90.

Snake River Valley, 236 e seq., 298.

Snowdon, 145, 171.

Snowy vole, 289.

Soleure, 133.

Solferino, 135.

Solway Glacier, 153, 155, 180.

Somme, terraces of the, 186, 262 e
S€q., 285, 286, 355, 359 et seq.

Sonora, Cal., 294 e¢ seq.

South America, existing glaciers of,
17; ancient glaciers in, 126.

Southampton, England, 266.

South Dakota, 96, 98.

Spain, ancient glaciers of, 136; human
relics in glacial terraces of, 264;
Quaternary animals of, 280.

Speeton, 140, 155, 156.

Speneer, cited, 224.

Spencer, N. Y., 220.

Spitzbergen, 12.

Spy, man of, 275, 277.

St. Acheul, 263.

Stag, 289.

Stainmoor, England, 154, 157, 180.

Stalagmite, rate of accumulation of,
302 et seg.

Serene Ge Cal., 294.

St. Anthony, Falls of, 340 e seg.,
364.

Steamburg, N. Y., buried channel at,
206.

St. Elias, 30 e¢ seq., 212.

384

St. Lawrence River, glacial drainage
‘of, 335, 339.

St. Louis, Mo., 119, 364.

St. Paul, Minn., 228.

Stone on kames in Maine, 80.

Straits of Dover, 360.

Straits of Gibraltar, 292.

Striz, direction of, in New Hamp-
shire, 69; in Lake Erie, 104; pres-
ence of, in Pennsylvania, 85, 119;
in Ohio, Indiana, Illinois, and Mis-
souri, 119; in Stuttgart, 279.

Subglacial streams, 28, 29, 120.

Submerged channels on the coasts
of America, 194-198.

Submergence theory, 60-63, 70.

Subsidence of the Isthmus of Pana-
ma, 118, 318; in Mississippi Val-
ley, 93, 118, 120, 121; on east coast
of North America, 255 e& seq.;
about the Great Lakes, 224, 339;
in Great Britain, 167-181.

Susquehanna River, glacial drainage
of, 93, 232, 257.

Svartisen Glacier, 13.

Svenonius, Dr., 12.

Sweden, 81.

Switzerland, existing glaciers of, 9-
11; ancient glaciers of, 131-136;
lake-dwellings in, 281.

300.

|
Table of changes during the Glacial |
| Upham, on drumlins, 73; on two ice-

epochs, 324, 325.

Tagus, valley of the, 367, 371 e seq.

Tait, cited, 362.

Tardy, cited, 370.

Tasman Glacier, 16.

Teesdale, England, 155, 157.

Terminal moraines, formation of, 6;
in Pennsylvania, 61, 62, 85 e¢ seq.;
on the southern coast of New Eng-

‘ land, 66 et seg.; in Ohio, 106; in
Puget Sound, 122; in Tyghee
Pass, 122; in Italy, 135.

Terminal moraines of the second
Glacial epoch, 93, 100, 101, 106.
Terraces. (See GLActAL TERRACES.)

Tertiary animals, 286.

Tertiary man, 365-374.

Tertiary period, climate of, 113, 117,
182, 305, 807.

Teton Mountains, 123.

Texas, Pleistocene animals of, 288.

Thames, England, 138, 264, 285.

Thenay, France, supposed Tertiary
man in, 367, 371; view of flint-
flakes collected at, 368.

Thompson, 50.

MAN AND THE GLACIAL PERIOD.

Thomson, cited, 362.

Till, description of, 53 ; composition
of, in Massachusetts, 81 et seq.;
section of, in Ohio, 108; depth
of, in Germany, Scandinavia, and
Russia, 182.

Tiniére River, 354.

Titusville, Pa., 232.

Todd, on forest beds and old soils,
110 et seg. ; cited, 228.

Torquay, England, 267.

Trade-winds of the Atlantic, 314,
318s.

_ Tremeirchon, Wales, 271.

Trenton, N. J., 87, 282, 242 et seq.,
254, 257 ; view of implement found _
at, 247.

Trenton gravel, section of the, 246.

Trent, valley ot the, 163, 164.

Trimmer, quoted, 148.

Trimingham, England, 162.

Trogen, Switzerland, 60,

Trons, Switzerland, 60.

| Tuolumne County, Cal., 294, 299.

Turin, 135.

Tuscarawas Valley, 220, 221, 232,
251; buried channel in, 2085.

Tylor, cited, 359 e¢ seq.

Tyndall, 44-46, 49.

Tynemouth, England, 155, 157.

| Tyrol, 134, 135, 211.
Table Mountain, Cal., 294 e& seq., |

Tyrrell, cited, 109.
Ulm, 134.

movements, 97; cited, 222, 2538 @
séqg., 801, 318, 320 et seq., 380, 348;
on the Columbia gravel, 261; on
date of the Glacial period, 344.
Ural Mountains, 15, 280.
Utah, 123; lakes of, 233.
UiticayNenye.220:
Utrecht, moraine near, 181.

Valais, the, 183.

Vegetable remains in glacial de-
posits, 117, 125; in Ohio, 107, 117;
in Indiana, 107 ; in Minnesota, 107,
109; in Towa, 108; in British
America, 109.

| Veins in glacial ice, 3.

Vermont, Runaway Pond in, 207.
Vernagt Glacier, 211.
Vessel Rock, view of, 56.

| Vezére, valley of, 281.

Victoria Cave, England, 270, 280.
Virginia City, 349.

Vivian, cited, 267.

Volga, the, 185.

Vosges Mountains, 136.

INDEX. 385

Wabash River, 220, 231, 232.

Wahsatch Mountains, 237.

Wales, ancient glaciers of, 143, 150
et seg.; caverns of, 271.

Wallace, cited, 331, 343, 362.

Walrus, 262, 285.

Warren, Pa., buried channel near,
206.

Warren River, 226.

Washington, 1, 21, 122.

Washington, D. C., gravel deposit
of, 254.

Water, transporting power of run-
ning, 5, 51-53.

Waveney, England, valley of the,
266. ;

Wealden formation, 301.

Weasel, 290.

Wells, England, 270.

Western Reserve Historical Society,
104.

Weston, W. Va., 216.

West Virginia, 214 e¢ seg.; glacial
terrace in, 216.

Wey, valley of the, 265.

Whitby, England, 155.

White, cited, 215 e seq.

White River, Ind., 232, 251.

White Sea, 181.

Whitney, 14, 21, 295, 349, 373.

THE

Whittlesey, 100.

Wild-boar, 290.

Wild-cat, 290.

Winchell, Alexander,
330.

Winchell, N. H., cited, 107, 210, 252:
on the Falls of St. Anthony, 341
et seq.

Wisconsin, 98, 99, 100, 101.

Wocikoff, cited, 316.

Wolf, 270, 290.

Wolverine, 289.

Wood, cited, 179.

Woodward, quoted, 160; on age of
Niagara, 337 ef seq.

Wookey Hole, England, 270.

Wrangell, cited, 357.

Wright, 373.

cited, 321,

Yankton, 120.

Yellowstone Park, 122.

Yorkshire, 140,154, 155, 157, 176, 270,
288, 286.

Yosemite Park, 21, 350.

Young, Rev. Mr., 24.

Young, Professor, cited, 362.

Younglove, 104.

Zermatt Glacier, view of, 2.
Zuyder Zee, 181.

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WE PLAVITME NATURALIST, By Diealeee:
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WE NATURALIST (ON TEE Teh aae
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