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.
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).
As has been said, three formations are recognized which were laid down otherwise than by glacial ice-sheets, the Bridgeton, the Pensauken, and the Cape May. The deposition of the Cape May is regarded as being contemporaneous with the Wisconsin ice-sheet (Salisbury and Knapp, New Jersey Geol. Surv., vol. VIII, p. 162; Lewis and Kümmel, Bull. 14, p. 120). The Pensauken formation is believed to be much older than the Cape May; it may (Salisbury and Knapp, op. cit., p. 78) be older than the extra-morainic drift, mentioned above as being of about Kansan times; but it may have coincided in part only with the Kansan. According to Lewis and Kümmel (op. cit., p. 111) the old, extra-morainic, Jerseyan drift was coincident with at least the later stages of the Pensauken. Hence, we may believe that the Pensauken corresponds somewhat to the Aftonian stage of Iowa. The Bridgeton formation is still older than the Pensauken and, being Quaternary, must be referred either to the early part of the first interglacial or to the first glacial; but the New Jersey geologists are not specific on this point.
It is unfortunate that nowhere in New Jersey has any considerable number of species of Pleistocene vertebrates been found buried together. We are thus deprived of one means of estimating the age of the species and of the beds. Most of the specimens found, as the mastodon and the two elephants, belong to species which lived during the whole or a large part of the Pleistocene and hence do not testify definitely to the age of the deposits in which they occur. Too often the information we have regarding the place and conditions of burial is extremely meager.
In Salem County a mastodon has been found in Mannington Township, at Chestnut Hill (p. [63]); and a deer, probably Odocoileus virginianus, at Woodstown (p. [226]). Although the geological map shows that in Mannington Township Cape May Pleistocene prevails, while about Woodstown there is Pensauken, one can not well conclude that the animals are of corresponding age.
In Gloucester County Mammut americanum has been found at Harrisonville (p. [63]), Mullica Hill (p. [64]), and Woodbury (p. [64]); Equus at Swedesboro (p. [184]). As to the former species, we can not be certain of the age, either from our knowledge of the age of the deposits inclosing the remains or from the history of the species. As to the horse found at Swedesboro, one may, from the history of the genus in this country, arrive at some conclusion; but this will be deferred to page 303.
In Camden County, so far as the writer has knowledge, no vertebrate remains have been found except in the Fish House beds, along Delaware River, just above Camden; but the horse remains (p. [184]) are of great importance. These beds were originally supposed to be of Cretaceous age, but in 1869 (Trans. Amer. Philos. Soc., vol. XIV, p. 250), Cope expressed the conviction that they belonged to the Pliocene period. He presented a geological section (fig. 7) of the beds which shows a thin stratum of soil above, then from 8 to 15 feet of light-brown sand, followed below by a blackish clay about 25 feet in thickness. Near the bottom of the latter was found a layer containing shells of several species of Unio and Anodonta. Just above this bed of unios there was discovered a large part of a skull of an extinct horse which Cope referred to Equus fraternus. This was deposited in the collection of the Academy at Philadelphia, but later disappeared.
Fig. 7.—Geologic section of Fish House beds, Camden, New Jersey. Redrawn from Cope.
In 1897 (Rep. State Geologist, New Jersey, for 1896, pp. 201–247, plates X-XIV) Woolman published a paper on the stratigraphy of the Fish House beds and described and illustrated other horse-teeth which he referred to Equus complicatus. These teeth were found at a depth of 12 feet below the top of the black clay; 6 feet of surface gravels had been removed from the clay. The teeth are now in the collection of the Academy, at Philadelphia. Woolman stated that in the same collection are a patella and a fragment of a long bone of a horse found in the black clay, in 1892.
Woolman regarded the clay in question as belonging to Pensauken times. Salisbury and Knapp (op. cit., p. 104, fig. 49) state that there is here 20 feet of black clay overlying Pensauken sand and that the clay is overlain by Pensauken gravel. If this judgment of the geological age of the clay is correct, the horses probably lived during the first interglacial (Aftonian) or the beginning of the second glacial stage (Kansan). There are, however, those who insist that these Fish House clays belong really to the Cape May formation. This would make the geological age of the horse about that of the Wisconsin drift.
Besides the horse remains, only some bones of a wolf have been found in the clays mentioned, and these too have disappeared. They probably would have thrown little light on the age of the beds. We must reach conclusions from other data.
This fact seems to be pretty certain: Had horses lived at Fish House during the deposition of the Cape May they would (as did the mastodon, Elephas primigenius, and E. columbi) quite certainly have spread out over northern New Jersey and over the grassy plains of New York and Ohio; and their remains would somewhere have been found, as are those of the other species just mentioned, in old swamp and lake deposits overlying the Wisconsin drift; but no horse remains have ever been reported from such deposits. Furthermore, in all the digging that has been done at Trenton, in deposits acknowledged by all to belong to Wisconsin times, no trace has been found of horse remains.
Near the bottom of the Fish House clay bed, just below the level of the horse remains, there is found a layer which contains river clams represented by the genera Unio and Anodonta. Ten species of Unio have been recognized and two of Anodonta. When these were first studied the beds were believed to belong to the Cretaceous. Nevertheless, the close resemblance of the shells to still living species was recognized; and to them were given names differing from those of the related existing forms by the ending oides. The species were described by Lea and Whitfield and have been restudied by Dr. H. A. Pilsbry, of the Academy of Natural Sciences, Philadelphia. The species are probably identical with forms yet living; but half of them no longer exist in the region of Delaware River. Pilsbry (Proc. Acad. Nat. Sci. Phila., 1896, pp. 567–570) stated that five of them have no longer any representatives in the Atlantic drainage south of the St. Lawrence River system. It is probable that these species had, when they lived at Fish House, spread into other rivers south of the Delaware and thus were not trapped in this river by the Wisconsin ice. It seems certain, therefore, that a longer period of time and a longer series of vicissitudes must have intervened to produce such changes in geographical distribution. According to C. T. Simpson’s work, “Descriptive Catalogue of the Naiades,” 1914, Unio (Quadrula) subrotundus now inhabits the Ohio, Cumberland, and Tennessee Rivers; U. (Lampsilis) anodontoides occupies the Mississippi River and Gulf drainage regions; while Anodonta corpulenta is found in the Upper Missouri region. The Wisconsin ice-sheet and the short period of time since its disappearance are hardly sufficient to explain this wide dispersion of species, while others have been able to retain their place in the Delaware.
Opposed to this view regarding the identity of the unios of the Fish House beds, see Ortmann (Proc. Amer. Philos. Soc., vol LII, p. 280, 1913) and Baker (Univ. Ills. Bull., XVII, p. 205, 1920). These writers contend that the species have no especial relationship to western forms. According to Baker the deposits are older than the earliest glacial stage. On the other hand, according to Dr. E. W. Berry (quoted by Baker), who has studied the plants, the beds belong to the late Pleistocene.
We have, then, these reasons for holding that the Fish House clays are of early Pleistocene age: (1) Competent geologists have determined them as belonging to the Pensauken formation, laid down at or before the time of the Kansan stage; (2) the presence of remains of horses, evidences of whose existence during or after the Wisconsin have not been produced; (3) the presence of many species of naiades, some of which yet live in that region, but the majority of which now live only in far-distant regions.
We may confidently conclude that the horse remains which were found at Swedesboro belonged likewise to the Pensauken.
In Burlington County mastodons have been found at Pemberton ( p. 64), but one can not be certain of their geological age. A reindeer has been unearthed at Vincentown (p. [64]). It seems highly probable that it lived there while the Wisconsin ice-sheet occupied the northern part of the State; but there is a possibility that it is older. In the Academy of Natural Sciences at Philadelphia are some remains of Odocoileus found at Vincentown (p. [227]).
In the vicinity of Trenton, Mercer County, scant remains of six species of Pleistocene mammals have been reported. These are Mammut americanum (p. [64]), Elephas primigenius (p. [132]), Bison bison (p. [287]), Ovibos moschatus (p. [248]), Cervus canadensis (p. [237]), and Rangifer caribou? (p. [248]). All are known to have existed elsewhere during late Pleistocene times, and three indicate a cold climate. The presence of fossil vertebrates here is of special interest because many evidences have been found of man’s occupation of the region in apparently late Pleistocene times.
At and in the vicinity of Trenton are found both Pensauken and Cape May deposits, the latter overlying the former (Salisbury and Knapp, op. cit., pp. 120, 165). The Cape May rises about 60 feet above sea-level. At various places the Pensauken protrudes through the mantle of Cape May and rises to a height of as much as 130 feet above sea-level. Its base is about 20 feet above sea-level. The materials consist of sand, gravel, and cobblestones. So far as the writer knows, no fossils have been found in the Pensauken about Trenton.
The Cape May at Trenton is held to have been laid down principally during the presence of the Wisconsin ice-sheet in the northern part of the State; and naturally it consists mostly of sands, gravels, coarse and fine, and some boulders. In the localities where excavations have been made for sand and gravel for building purposes, for sewers, and for railroads, and in search for relics of man, two principal divisions are recognized. Below are strata of clays, sands, gravels, and boulders which are believed to have been deposited by the floods of varying intensity which issued from the glacial moraine then about 60 miles above Trenton (figs. 8, 9). Over this lies a bed of what is called yellow drift, which reaches a thickness of about 3 feet. It consists mostly of fine sand, but there are many pebbles and occasionally some large boulders. It is everywhere characterized by wavy red bands. While some geologists have held the opinion that this deposit had been produced by winds, it appears to be definitely determined that it was waterlain (Wissler, Scient. Monthly, vol. II, p. 237). This “yellow drift” is overlain by about a foot of black soil which belongs to the Recent epoch and is the result of cultivation by whites. For details regarding the Trenton gravels and the yellow sands above it the reader should consult Ernest Volk’s work, “Archæology of the Delaware Valley” (Papers Peabody Mus., vol. V, 1911).
All the species mentioned above have been reported from the beds known as the Trenton gravels. A femur of a bison was found also in the yellow drift (see p. [287]).
Monmouth County has furnished more fossil vertebrates of the Pleistocene than any other county. Mastodons have been discovered at Englishtown, Freehold, Marlboro, Long Branch, Manasquan, and in the Navesink Hills (pp. 65, 66). Many specimens, as those about Freehold and Long Branch and Manasquan, are in such superficial positions in peat that they do not seem to be very old, probably of Cape May age; and yet of this one can not be wholly certain. The discovery of a heel-bone of a megatherium (p. [31]) at Long Branch appears to indicate the presence there of early Pleistocene deposits. At Englishtown the remains had apparently become mixed with marl, and they may belong to an older stage of the Pleistocene. In the Navesink Hills, according to Leidy, the mastodon remains were associated with those of an extinct horse (p. [184]). If so, both species probably were buried in Pensauken deposits. In this same region there was found long ago a tooth of Elephas columbi (p. [149]); but it is useless to speculate on its geological age. At Long Branch (p. [26]), damaged skulls of walruses, probably of the existing species, have been met with. It seems natural to associate this southward migration, which extends to South Carolina, with the Wisconsin epoch; but it is possible that it was earlier. At Deal (p. [227]) have been found remains of a deer, probably Odocoileus virginianus.
Fig. 8.—Sketch of vicinity of Trenton, showing distribution of Trenton gravels. Redrawn from Salisbury and Knapp.
Fig. 9.—Sections taken at Trenton, New Jersey.
Upper figure taken along the line 3 of Fig. 8.
Lower figure taken along the line 2 of Fig. 8.
The black represents the glacial gravel. A, the crystalline rock of the region; T, Trias; K, Cretaceous; Pp, Pensauken; O, sea-level.
Somewhere about Shark River, a tooth of a peccary (p. [213]) was found, as was supposed, in Miocene marl. Leidy could not distinguish this tooth from that of Mylohyus nasutus. So far as our evidence goes, this species belongs to the early and middle Pleistocene.
Near North Plainfield a tooth was found which is referred to Elephas primigenius (p. [133]). The locality is very close to the moraine of the Wisconsin ice-sheet, and the animal probably lived there when the Plainfield outwash plain (Salisbury, Geol. Surv. New Jersey, vol. V, 1902, p. 738) was being laid down.
Near Schooley’s Mountain, but west of Musconetcong River and in Warren County, remains of a mastodon (p. [67]) were encountered in excavating the Morris Canal. It is probable that these were buried in a swamp left over from the Wisconsin times; but Lewis and Kümmel’s map of 1910–1912 indicate in this region only drift older than the Wisconsin.
The mastodons found at Hackettstown and Hope, in Warren County, are probably of Late Wisconsin origin (pp. 67, 68).
Near Mount Hermon, about 5 miles northeast from Delaware, in Warren County, and about 2 miles northwest of Hope, was found the splendid skeleton of the moose Cervalces scotti, which forms one of the treasures of Princeton University (Scott, Proc. Acad. Nat. Sci. Phila., 1885, p. 174). It was discovered in a bog. All this region is (Salisbury, Geol. Surv. New Jersey, vol. VIII, plate XXVIII) occupied by Wisconsin drift and the bog doubtless rested on this drift. It seems certain, therefore, that this stately relative of our existing moose lived after the disappearance of the Wisconsin ice-sheet.
A mastodon (p. [68]) which was found at Greendell in Sussex County quite certainly lived there after the last glacial stage.
Berry (Torreya, vol. X, p. 261) has studied a collection of nine species of plants which had been obtained in peat from near Long Branch. Only three of these now range north of Long Branch. He concluded that the last glacial stage had been followed by a period of climate warmer than the present climate. This is in accord with views which the present writer has held. It ought not, however, to be assumed with too much confidence that the peat-bed is of Late Wisconsin origin.