The Pleistocene of North America / and its vertebrated animals from the states east of the Mississippi River and from the Canadian provinces east of longitude 95°

by Oliver Perry Hay

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.