part of the United States, the land thus occupied, and probably a
considerable area beyond the ice, became depressed. The valleys of the
St. Lawrence, the Ottawa, the Hudson, and the Connecticut had been
pressed down to such an extent that, as the ice-sheet retired these
valleys became filled with water standing at sea-level. When at length
the glacial front had retreated beyond the St. Lawrence, sea-water
entered Lake Ontario and passed up Ottawa River far above the city of
Ottawa (Leverett, Monogr. U. S. Geol. Surv., LIII, plate XXI). South of
the St. Lawrence, marine waters occupied what is now Lake Champlain and
as much of the surrounding land as was then at or below sea-level. In
his account Fairchild makes use of the plate which is here reproduced
(map 31) from his article of 1917 (Bull. Geol. Soc. Amer., vol. XXVIII,
p. 279, plate XI). This geologist believes that the Hudson formed for a
while a connection with Lake Champlain, although the Hudson waters may
not have been actually saline. But in Lake Champlain the presence of
fossil marine mollusks and at least one whale skeleton shows that its
waters were salt. The lines crossing the plate obliquely are the
isobases which show the amount of elevation which has taken place along
those lines since the end of the Pleistocene. South of New York City
this is zero. At the northern end of Lake Champlain the elevation is 800
feet. This means that the north end of the lake for a while stood 800
feet lower than now. Marine fossils have, however, been found at an
elevation of only about 300 feet. The waters which first occupied the
lake and stood at the highest level were of glacial origin and fresh.
When the ice-front had receded so as to open the St. Lawrence and admit
sea-water, the northern end of the lake had been uplifted about 500
feet. It was then that the marine animals entered.
Other important papers to be consulted in this connection are as
follows: One by J. B. Woodworth (Bull. 84 New York State Mus.); one by
Charles E. Peet (Jour. Geol., vol. XII, 1904, pp. 415–469; 617–660), and
two by Professor Fairchild (Bulls. 105, 127, New York State Mus.).
It is proper to say that certain glacial geologists maintain that the
depression in the New England States has been less than supposed by
Fairchild, and that the isobases curved around toward the north as the
New England coast was approached, somewhat as represented by Taylor
(Monogr. LIII, U. S. Geol. Surv., p. 503). Fairchild, in a later paper
(Bull. Geol. Soc. Amer., vol. XXIX, 1918, pp. 187–244), has reached the
same conclusion and presented a map on which are drawn the isobases, or
lines passing through points affected by the same amount of post-glacial
uplift; from this map 32 has been prepared. On his map the location of
the heavy or solid lines is regarded by Fairchild as being based on
clear evidence. Where the lines become thin the evidence is less
trustworthy; where the lines are broken their positions are
hypothetical. The numerals on the lines show the amount of uplift along
those lines. Two points of importance are brought out on the map. The
first is that Newfoundland formed an independent center of glaciation
and of subsequent uplift, a conclusion based on good geological
evidence. The second point is that the center of the Wisconsin
glaciation was located southeast of James Bay, considerably farther
south and west than is usually supposed. The confirmation of this is
left to the future.
It does not seem to have been demonstrated that there are in Connecticut
any Pleistocene deposits older than those laid down by the Wisconsin
ice-sheet. In case Fuller (U. S. Geol. Surv. Prof. Paper 82) is correct
in his determination of beds of the early, middle, and late Pleistocene
on Long Island, it is to be expected that beds of corresponding ages
will yet be recognized in Connecticut. Woodworth (17th Ann. Rep. U. S.
Geol. Surv., pt. 1, p. 978) mentions deposits of clay at Berlin and at
New Haven that may be older than the Wisconsin.
While the correlations recorded above of the Pleistocene of the New
England States with the glacial and interglacial stages of the
Mississippi Valley may be subject to modifications, it is interesting to
learn that the presence of Middle and Early Pleistocene deposits in the
Eastern States has received the recognition of so many students of
glacial geology. The hope is awakened that in New England there may yet
be found interglacial deposits which will furnish remains of Pleistocene
vertebrates, as these have come to light from Throg’s Neck, New York, to
southern Florida. It is possible that the astragalus of an equine animal
(p. 183), found at Gay Head, Martha’s Vineyard, belongs to a species of
_Equus_ of early Pleistocene age.
In order to illustrate still further the events connected with the
history of the Pleistocene in the region of the Great Lakes, three
additional figures are introduced. One of these (map 33) shows J. W.
Spencer’s conception of the drainage of the region in preglacial times.
The areas now occupied by the lakes were then traversed by rivers. It
will be observed that the rivers above Pittsburgh now discharging into
the Ohio then emptied northward into the Erigan. This is shown also by a
map (fig. 6) taken from Leverett (U. S. Geol. Surv. Monogr. XLI, p. 89).
Figure 5, on page 287, shows the position of the shore of this Champlain
Sea.
The number of Pleistocene vertebrates found in the New England States is
limited, and most of them have been mentioned.
Somewhere on the coast of Maine have been found specimens of the fish
_Mallotus villosus_ (Gould, Proc. Bost. Soc. Nat. Hist., vol. III, 1848,
p. 67). At Charlotte, Vermont, a white whale, _Delphinapterus
vermontanus_, was found many years ago (p. 19). Some bovid teeth were
found many years ago at Gardiner, Maine, and referred to _Bison bison_,
but it is now believed that they are teeth of the domestic ox. However,
Dr. G. M. Allen has reported from Cape Cod, Massachusetts, teeth of a
young bison (p. 266). At Woodbury, Washington County, Vermont, at a
depth of 7 feet, an antler and a piece of the upper jaw with five molars
of _Rangifer caribou_ (p. 244) have been discovered (Rep. Geol. Surv.
Vermont, vol VI, p. 7). Mastodons have been discovered in Massachusetts
at Coleraine and Shrewsbury (p. 47). Many years ago a tooth and a tusk
and some bones of an elephant were found at Mount Holly, Vermont (p.
148); the writer refers the animal to _Elephas columbi_. An undetermined
elephant has been found in Vermont at Richmond (p. 167). Walrus remains
have been recovered at Addison Point (p. 23), Andrews Island (p. 23),
Gardiner (p. 23), and Portland (p. 24), all in Maine; off Portsmouth,
New Hampshire (p. 25); and on Martha’s Vineyard, Massachusetts (p. 25).
At the latter place a tooth supposed to belong to the hooded seal (p.
26) was found long ago. With respect to the specimens found at this
place there is some doubt as to their geological age. With the exception
that the reindeer bones (p. 244) found near New Haven may be of
pre-Wisconsin age, no Pleistocene vertebrate fossils older than Late
Wisconsin appear to have been discovered anywhere in Connecticut. As
shown elsewhere (p. 48), there were found long ago at Sharon, Litchfield
County, remains which were identified as those of mammoth, but these
have since been regarded as those of the common mastodon. Only a single
vertebra was preserved.
[Illustration:
FIG. 6.—Probable preglacial drainage of the Upper Ohio. From Leverett.
]
Mastodons have been found in four other places, Cheshire, New Britain,
Bristol, and Farmington (pp. 47, 48). The animals which left their bones
at those places certainly lived after the last glacial sheet had
withdrawn from the State. As mentioned on page 291, Fairchild has found
reasons for believing that, while the Wisconsin ice-sheet was
withdrawing from the Hudson and Connecticut Valleys, the whole region
was so depressed that these valleys became occupied by water at
sea-level. In these waters there were laid down thick deposits which now
stand at levels much above tide, varying, in Connecticut, from nearly
200 to about 300 feet. Map 31, reproduced from Professor Fairchild
(Bull. Geol. Soc. Amer., vol XXVIII, 1917, plate XI) is intended to show
how wide an extent of territory along the Connecticut Valley was then
submerged. It is probable that the emergence of these deposits was not
accomplished until after the glacier had retired beyond the State.
It will be observed (map 6) that the localities just mentioned, where
the mastodons have been found, lie very close to or on the areas covered
by the deposits mentioned. The pond in which the Farmington mastodon
(fig. 6, No. 3) was buried is in a range of hills which must have stood
as an island in the Connecticut inlet. While it is possible that
mastodons lived on this island while the land was depressed, it is more
likely that they lived there after it had been more or less elevated.
Judging from the topographical maps, one may conclude that the mastodons
that have been found at Cheshire (fig. 6, No. 1) and New Britain (fig.
6, No. 2) were buried in deposits that overlie those laid down at
sea-level. Their time of existence must have been near the end of the
Pleistocene. Too little is known about the mastodons reported from
Bristol and Sharon to form any definite opinion about the stage of the
Pleistocene when they lived; but it was probably after the withdrawal of
the last ice-sheet.
NEW YORK.
From the geologist’s point of view there is hardly, if at all, another
State which presents for solution more numerous or more interesting
problems connected with the Pleistocene than does New York. Among these
are the geography and topography of the State at the beginning of the
Pleistocene; the number and identity of the glacial stages which
affected its surface; the origin and development of the bordering Great
Lakes, of the numerous interior lakes, and of the river courses, actual
and abandoned. For a knowledge of these one must consult the various
reports issued by the Geological Survey of the State; above all, the
numerous and instructive papers that have been published by Professor H.
L. Fairchild, of the University of Rochester.
For the student of Pleistocene vertebrate palæontology, the State of New
York is not so attractive as some others; but it is far from being
devoid of interest. Few species of vertebrates of Pleistocene age have
been found in its deposits, and these, with one exception, belong to the
latest episodes of the last glacial stage. So far as the writer is
aware, the following list comprises all of the Pleistocene vertebrates
known to have been found within the borders of the State; those marked
with an asterisk (*) are now extinct:
*Equus sp. indet (p. 183).
*Platygonus compressus (p. 212)
Bison bison (pp. 266, 267).
Odocoileus virginianus (p. 226).
Cervus canadensis (pp. 235, 236).
Rangifer caribou? (p. 245).
*Mammut americanum (pp. 48–63).
*Elephas columbi (p. 149).
*Elephas primigenius (pp. 131, 132).
Castor canadensis.
*Castoroides ohioensis (p. 272).
Deposits of materials belonging to Pleistocene stages older than the
Wisconsin are apparently of rare occurrence in the State. If existing
they are usually concealed beneath the widely spread Wisconsin drift. On
Long Island, Fuller (U. S. Geol. Surv. Prof. Paper 82) has described
beds of gravels, sands, and clays, which he regards as belonging to the
Nebraskan, Aftonian, Yarmouth, and Illinoian. None of these has
furnished any vertebrate fossils. However, in 1866 (Smithson. Contrib.
Knowl., vol. XV, art. 3, p. 16), Whittlesey reported that he had a tooth
of a horse (p. 183) found at Fort Schuyler, Throg’s Neck, 18 feet below
the surface. This must have been lying beneath the Wisconsin drift.
Inasmuch as Fuller has found the Manhassett formation, regarded as
equivalent to the Illinoian, around Manhassett Bay, within 4 or 5 miles
of Throg’s Neck, it seems entirely reasonable to suppose that deposits
of similar or earlier age exist at Throg’s Neck.
With the exception of small areas, the whole of the State was at one
time covered by the ice-sheet of the Wisconsin stage. The glacial ice
filled the basins of the Great Lakes, and overrode even the peaks of the
Adirondack and Catskill Mountains. Only along the southern side of Long
Island and in the loop formed in Cattaraugus County by Allegheny River
does the ice-sheet appear to have been absent.
Nearly everywhere, even on the southern coast of Long Island as outwash,
it left its burden of clay, sand, gravel and boulders, usually many feet
in thickness; in the mountainous regions this drift material is present,
at least in the valleys. At the extreme southern edge of the glacial
sheet there was laid down the terminal moraine, which, more or less
distinctly determinable, has been traced from the eastern end of Long
Island to the southwestern corner of Cattaraugus County, and onward into
Pennsylvania. This moraine is shown here on maps 3 and 6–A.
As the ice-sheet withdrew toward the north, the surface which it had
occupied was, for many reasons, very uneven, and in the depressions
there were formed numerous lakelets and lakes. Into the smaller lakes
and ponds especially, were swept, by running water and blown by winds,
coarse materials and dust, so that they began at once to fill.
Water-loving plants in due time took possession of their borders, and in
time marshes were formed. In some of these bodies of waters are now
found deposits of shell marl, which show that for a long period the
lakes and ponds were inhabited by fresh-water mollusks. Sometimes below
this marl, but usually above it, is found a layer of peat, the product
of the partial decay of the vegetation. It is in such peat-bogs,
sometimes buried in the peat, sometimes in the marl, that have been
found most of the bones and teeth of the fossil animals recovered.
Inasmuch as such deposits lie upon the Wisconsin drift, it is certain
that these animals lived, at the localities where found, after the
retirement of the glacier from that locality; how long afterward one
usually can not be certain.
It is in such Late Wisconsin deposits that have been found the numerous
remains of mastodons on Long Island, on Staten Island, around New York
City, and especially in Orange County (pp. 48–54). This county has
furnished some of the most complete skeletons of mastodons ever
discovered. Whether or not the conditions for their existence were more
favorable in this region than in that between this county and the Finger
Lake region may be regarded as doubtful; but it is certain that the
conditions for the preservation of skeletons were extremely favorable.
A remarkable case is presented at Cohoes, where a part of a skeleton of
a mastodon was found in one of the great pot-holes existing there, and
another part of the same skeleton in a neighboring pot-hole. The case is
discussed below.
In the western half of the State, after the foot of the glacier had
retired beyond the divide between the present northward and southward
flowing streams, bodies of water began to collect between the divide and
the foot of the glacier. To these bodies, regarded as lakes, changing
from time to time their dimensions and their outlets, have been given
various names. At first, the waters that collected in the Finger Lake
region found their outlet southward through the Susquehanna River; later
through the Mohawk and Hudson; then westward into the Mississippi
drainage; afterward through a channel leading around west and north of
the Adirondacks and into Lake Champlain and down the Hudson; and
finally, as now, into the St. Lawrence River (map 34).
The waters of the Erie basin, for most of the time, found their outlet
toward the west into the Mississippi; but at a later time they escaped
for a while eastward through central New York into the Mohawk. For
information regarding these lakes one must consult Leverett and Taylor
(Monogr. LIII, U. S. Geol. Surv.) and Fairchild (Bulls. 127, 160, N. Y.
State Mus.).
From a study of the geological history we may arrive at some
approximately correct ideas as to the time when the mastodons,
elephants, horses, giant beavers, etc., lived within the limits of the
State. Of these animals, apparently none of the specimens discovered up
to this time belongs to any pre-Wisconsin stage, except the horse whose
tooth was found at Throg’s Neck (p. 183). The history of our extinct
horses and the depth at which the specimen was found indicate that the
animal had lived either during the first or the second third of the
Pleistocene.
We may be certain that none of the mastodons (p. 49) which have been
reported from Long Island lived there while the northern border was
occupied by the glacier, and the remainder by the ocean. Not until the
land had risen to about its present level could mastodons have become
buried in the muck-filled ponds where they have been met with. Where the
glacier front was when mastodons got foothold on the island we can not
tell certainly; but it required perhaps hundreds or probably thousands
of years for the elevation of the island to the extent of about 100
feet. We can hardly doubt that the mastodon lived on up to near,
possibly into, the Recent period (see map 34).
It is interesting to speculate on the time and manner of entombment of
the skeleton, described on page 56, which was found at Cohoes, part in
one pot-hole, part in another not far away. Hall adopted the theory that
the carcass of the mastodon had been frozen in the glacial ice and, on
the thawing of this ice, had been dropped into the pot-holes. In fact,
he thus explained the frequent presence of mastodon skeletons in swamps.
We have, however, no evidence that mastodons were ever thus frozen up in
the ice of the glacier; but there is a possibility that this happened
sometimes. If a skeleton should thus have been engaged in the moving
stream of ice it is not probable that it would ever have emerged in a
recognizable condition. In the production of cracks and crevices in the
glacial ice, of which Hall spoke, the bones would have been broken up
and scattered, if not ground to powder. If a cadaver had been frozen in
the ice for any considerable time it would certainly have come out in
such a waterlogged condition that it would hardly have floated. Weighted
down by its heavy tusks, it would have drifted against rocks and at
least the tusks would probably have been broken off. If we exclude the
idea that the mastodon had first been frozen in the glacier, the writer
sees no reason for denying that it might thus have been transported for
some distance; but little is gained by granting it. The animal could as
well have lived near Cohoes as farther up the Mohawk.
As stated on another page, James Hall concluded that the pot-holes
belonged to some preglacial time. Professor H. L. Fairchild has
expressed in a letter to the present writer the following opinion:
“When the ice-sheet melted from Cohoes the locality was 355 feet
lower than it is to-day. Deep estuary deposits partially filled the
Hudson Valley and buried the Cohoes district. The Mohawk channel at
Cohoes is excavated through marine sediments. There is no suggestion
of any river channel there previous to the present river work. The
pot-holes are post-glacial, but they probably represent a more
copious and vigorous flow than that of the present river. That was
supplied by the diminishing Iromohawk, the latest outflow through
the Mohawk Valley of the Iroquois water. In this view the pot-holes
were drilled by the latest glacial waters.”
It appears that, when the mastodon skeleton fell into the pot-holes,
these had been drilled long before; for the principal one had become
filled with gravel to a depth of at least 10 feet. They were, therefore,
probably well above the stream-level, except in times of high-water.
However the carcass reached the locality, it must have arrived in a
complete state. Had it already attained an advanced stage of decay, some
limbs or the feet or the lower jaw, probably the whole head, weighted
down as it was by the heavy tusks, would have dropped off. It may be
assumed that the skeleton was lying on land or in some pond not far
above the pot-holes. The flesh was not wholly decayed, and the bones
were held together by the ligaments. While the skeleton was in this
condition the river rose and swept it over the first pot-hole, where the
right leg dropped off; and then onward over the second, where more of it
was deposited. Some unimportant parts may have been carried farther, and
some of the missing bones may have decayed in the pot-holes. After the
bones were deposited there the pot-holes became slowly filled up,
probably mostly during times of high-water, with muck and branches and
trunks of trees of several species (Hay, Science, n. s., vol. XLIX,
1919, p. 378).
The retreat of the Wisconsin ice-sheet far beyond the St. Lawrence and
the rise of the land to its present elevation, 350 feet above the sea at
Cohoes, belong to the closing chapter of Pleistocene history. When the
Cohoes mastodon was buried the ice-sheet was probably already north of
the St. Lawrence and, as Professor Fairchild writes, 150 feet of the
rise of the land had already occurred. The time could, therefore, not
have been long before the beginning of the Recent epoch. If these
animals lived at such a late time at Cohoes they doubtless existed at
the same time in all parts of the eastern region where their remains
have been discovered. They may have been able to occupy Long Island a
little earlier than places further north, but the interval would be
geologically inconsiderable.
The writer has learned of no discoveries of mastodon bones in materials
laid down by the marine waters that occupied Lake Champlain, the St.
Lawrence Valley, and that of Ottawa River, or in deposits overlying
these marine beds.
On the basis of one of Professor H. L. Fairchild’s plates (Bull. 127, N.
Y. State Mus., plate XXXV) the writer has prepared map 34, which is
intended to show the position of the Wisconsin ice-sheet in New York
after it had retired somewhat north of the divide. This divide is marked
by a line of dots. The area then occupied by the ice is stippled. Lake
Erie was already nearly free from ice and was discharging its water by
way of the Mississippi. Impounded waters from the melting glacial ice
were collecting in the region of the Finger Lakes, forming Newberry
Lake, and escaping down the Susquehanna. The Mohawk afforded outlet for
the water from the southeastern lobe of ice. Fairchild’s plates 36 to 42
show the successive positions occupied by the ice-front as it retired
northward and the various lakes that were formed.
Although not many species of vertebrate animals have been found in the
Pleistocene deposits of New York, a large number of localities have
furnished remains of the mastodon, _Mammut americanum_. These localities
are recorded and brief descriptions of the remains and their geological
environment have been presented on pages 48–63. The localities are
indicated on map 34. It will be seen that several specimens have been
found on Long Island and many in Orange County, in the southeastern
corner of the State. In the western half of the State most of the finds
occur within the area once occupied by the successive lakes. The animals
could have lived there only after the ice-sheet and the lake waters had
disappeared. It will be seen that a few finds have been made close to
the shores of the present lakes. The animals must have lived there at
the very end of the Pleistocene, if not within the Recent epoch.
The finds of other vertebrates are recorded on the following pages:
_Equus_ sp. indet. on page 183; _Platygonus compressus_ on page 212;
_Bison bison_ on page 266; _Odocoileus virginianus_ on page 226; _Cervus
canadensis_ on page 235; _Rangifer caribou_ on page 245; _Elephas
columbi_ on page 149; _Elephas primigenius_ on page 131; _Castor
canadensis_ on page 272; _Castoroides ohioensis_ on page 272.
In 1850 (Proc. Amer. Assoc. Adv. Sci., vol. II, pp. 255–256), W. C.
Redfield reported that he had received remains of a fox of the genus
_Vulpes_ from Gulf Summit, Broome County. The lower jaw and other bones
had been discovered in a cutting of the New York and Erie Railroad, 40
feet below the natural surface. The deposit above these bones was
evidently the Wisconsin drift. The fine clay inclosing the bones may
have belonged to the Sangamon, or even some older interglacial deposit.
It is impossible to say whether this fox was _Vulpes fulvus_ or _Urocyon
cinereoargenteus_.
NEW JERSEY.
(Map 6–A.)
In the consideration of the problems of Pleistocene geology and
palæontology, New Jersey is one of the most important States. Its
northern part is occupied by glacial drift deposits, while the southern
two-thirds is covered more or less completely by materials laid down
beyond the limits of the glaciers. The glacial materials appear to
belong to two widely separate epochs. The geologists who have been
connected with the geological survey of New Jersey recognize in the
materials composing the Pleistocene deposits south of the glacial region
three formations, the Bridgeton, oldest; succeeded by the Pensauken; and
the Cape May, the youngest. The geologists of Maryland recognize in New
Jersey three formations which correspond to the three of Maryland, the
Sunderland, the Wicomico, and the Talbot. However, the author of the
Maryland Pliocene and Pleistocene volume, Professor Shattuck, insists
that parts of Salisbury’s Bridgeton, Pensauken, and Cape May all enter
into the Sunderland; parts of the Cape May, Pensauken, and possibly of
the Bridgeton, into the Wicomico; and parts of the Pensauken and Cape
May into the Talbot.