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

(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.

There are wide divergences in the views of the two groups of geologists regarding the manner in which the materials have been laid down. The Maryland geologists hold that their three terraces represent three epochs of submergence, and that the gravels, sands, and clays were deposited in the salt waters of the ocean or of estuaries. Salisbury and Knapp (Geol. Surv. New Jersey, vol. VIII, 1917, p. 3) adopt the view that the formations are partly of subaerial and partly of marine and estuarine origin, with emphasis on the subaerial mode. Of the Bridgeton, the authors referred to say (their p. 18 ) that the accessible parts are primarily of terrestrial origin. A part of what remains may be marine or estuarine, and part of what has been removed may have been so. No palæontological evidences of marine deposits of this epoch are found in the State. The writer records his dissent from the theory that the terraces and the deposits called the Sunderland, Wicomico, and Talbot have been the product of marine submergence. A part only of the Talbot can be referred to deposition in the sea.

Of the Pensauken, Salisbury and Knapp say (p. [87]): “There is nothing in its constitution to negative the hypothesis of the whole formation being river work; nor is there anything, as now understood, to prove it.” As to the deposits which they refer to the Cape May, the authors quoted say (p. [162]) that the southern part of the State seems to have stood a few feet (30 to 50) lower than at present; but that it could not have stood long at this height, for sea-cliffs are essentially wanting. At one point, near Millville, Cumberland County, marine fossils are met with at an elevation of about 10 feet above tide.

The Cape May was, according to Salisbury and Knapp, laid down during the last glacial epoch, the Wisconsin (p. [162]). This determination of age would doubtless gain the acceptance of the Maryland geologists and their adherents, although the latter would include under this name many local deposits which Salisbury puts in the Pensauken.

It is remarkable that, so far as the writer knows, no remains of Pleistocene vertebrates have ever been discovered in that portion of New Jersey which is mapped as occupied by the Cohansey sands, an area including nearly half the State. It lies southeast of a straight line which would run from Navesink River to Salem. The reason for this lack of fossil vertebrates does not occur to the writer. A large portion of this region is mapped as being covered with deposits of all three of the Pleistocene formations, Bridgeton, Pensauken, and Cape May. On or near to the line of outcrop of the Cretaceous deposits from Salem to Raritan Bay, not fewer than ten localities are known where mastodon remains have been discovered, besides two localities which have furnished horses and two which have furnished elephants. Since the southeastern part of the State has yielded no vertebrate fossils and little else to throw light on the age of its deposits, we shall dismiss it from consideration.

The glacial geology of the State has been studied by Professor Rollin D. Salisbury, of the University of Chicago, and his assistants, Henry B. Kümmel, Charles E. Peet, and George N. Knapp. The results of their studies on the glacial-drift deposits have been published in volume v of the final report of the State geologist, 1902.

The Quaternary formations of the southern part of the State are described in volume VIII of the final report. A more succinct description of the events of the Quaternary period is found in Bulletin 14 (1915) of the New Jersey Survey. The authors are J. Volney Lewis and Henry B. Kümmel.

In the vicinity of Perth Amboy is a heavy glacial moraine which may be traced eastward through Staten and Long Islands. West of Perth Amboy it turns northward, and swinging around it reaches Springfield. Thence it runs northwestward to Rockaway, and continues west by south to Delaware River, at Belvidere. This moraine marks, in New Jersey, the southward limit of the last ice-sheet, the Wisconsin. All the drift deposits of the State north of this moraine are regarded as belonging to the Wisconsin stage. It is to be supposed that this is, at least to some extent, underlain by older drift deposits.

South of the moraine just described are scattered deposits of glacial drift and other evidence of glacial action which are referred to a much older ice-sheet, one supposed to correspond to the Kansan drift of the Mississippi Valley (Salisbury, Geol. Surv. New Jersey, vol. V, p. 781). On the other hand, it is sometimes referred (Chamberlin and Salisbury, Geology, vol. III, pp. 383, 384) to the first glacial (sub-Aftonian).