Chapter XVII: On the Theory of the Pleistocene Terraces of the Coastal Plain (18)

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.

PENNSYLVANIA.

About half of the area of Pennsylvania lies outside of the region which was glaciated. Figure 10 is a map taken from Folio 172 of the U. S. Geological Survey, published in 1910 and compiled by Dr. W. C. Alden in 1901. A broad strip along the southern part of the State, being non-glaciated, is not represented. The areas shaded by parallel ruling and stippling are those which present evidences of glacial action.

The glaciated area consists of two principal portions. One of these, that subjected to the action of the Wisconsin ice-sheet, is represented on the map by means of oblique parallel lines coming down to an interrupted heavy line. This line, representing the Wisconsin terminal moraine, starts on Delaware River north of Easton, runs northwestward to Potter County, thence into New York, thence back into Pennsylvania, in Warren County, and then enters Ohio north of the Ohio River. The course of this moraine was worked out especially by H. C. Lewis and G. F. Wright and was described in report L of the Pennsylvania Geological Survey, in 1881. The moraine crosses the Delaware at Belvidere, New Jersey, and passes through the following counties: Northampton, Monroe, Carbon, Luzerne, Columbia, Sullivan, Lycoming, Tioga, Potter, Warren, Crawford, Venango, Butler, Lawrence, and Beaver.

South of this moraine are two areas which, on this map, are represented by stippling. These are occupied by drift materials, usually forming a considerably thinner covering, which are believed by most glaciologists to belong to an older Pleistocene stage, probably about as old as the Kansan. Especially in the valleys these older drift deposits may reach thicknesses of 200 or 300 feet. These old glacial deposits are represented also by terraces along the margins of the valleys. Some of these in the vicinity of Warren stand at a height of about 1,400 feet above the sea. Figure 17 is taken from Shaw and Munn (Folio 178, U. S. Geol. Surv., p. 12). The uppermost gravels are supposed to represent the Kansan stage. A few small patches lying in the angle of the unglaciated area are of doubtful age, as indicated on the map. It must be stated, however, that there is some dissent from this conclusion as to the age of this outer drift. Professor E. H. Williams has published a number of papers in which he takes the position that this drift is a deposit laid down by the same ice-sheet that later on built up the Wisconsin moraine (Amer. Jour. Sci., vol. XLVII, 1894, pp. 32–36; Science (n. s.), vol. XXXVII, pp. 447–450; Pennsylvanian Glaciation, first phase, 1917, pp. 1–101). Professor G. F. Wright appears to take the same view. The writer sees no sufficient reason for distrusting the opinions of Dr. Alden and his colleagues.

It must not be assumed that an animal whose remains have been found within the area occupied by the Wisconsin drift lived during or after that stage. Even within this area there may occur fossil-bearing deposits of an older Pleistocene time. These older deposits may underlie the Wisconsin drift or they may occur as old terraces high up on the sides of the valleys of rivers. Cases of the latter kind are found along Allegheny River (Leverett. Monogr. XLI, U. S. Geol. Surv., pp. 229–252; Shaw Jour. Geol., vol. XIX, 1911, pp. 140–156; folio 178, U. S. Geol. Surv., p. 8). On the other hand, an animal of very late Pleistocene age, or even of the Recent, may be buried in deposits which overlie an old Pleistocene deposit. It is necessary, if it can be done, to determine the actual age of the deposit containing the remains; otherwise one must depend on the geological age of the species involved, or be content to wait for further information. Unfortunately, but few of the quadrangles in the glaciated area have had their geological structure studied and reported on. At present the U. S. Geological Survey has published only Folios 92 (Gaines) and 93 (Elkland and Tioga), lying mostly in Tioga County, partly in Potter; also Folio 172 (Warren), occupying a part of Warren County. Information may sometimes be secured from the numerous volumes which have been published by the Geological Survey of Pennsylvania and from articles in the scientific journals.

FIG. 10.—Glaciated areas of northern Pennsylvania. From W. C. Alden.
]

The Pleistocene deposits which lie outside of the glaciated areas have been mostly laid down along rivers. Some of the materials were transported by the streams which carried away the drainage from the glaciers; in other cases the materials were brought down from the higher lands and laid down along the lower and less sloping parts of the streams. In the unglaciated area many of the quadrangles have been surveyed by the U. S. Geological Survey and the folios aid in determining the age of deposits which contain fossil vertebrates.

Important collections have been made in a few localities, and these will now be considered:

At Pittston, in Luzerne County, on Susquehanna River, have been found teeth of the horse _Equus complicatus_ (p. 184), remains of mastodon (p. 68), and of a musk-ox (p. 248). The presence of the horse makes it evident that the deposit containing the fossils belongs to a stage older than the Wisconsin, although the locality is within the area of the Wisconsin.

We consider now the contents of a cave found near Stroudsburg, Monroe County. The Hartman (or Crystal Hill) Cave was discovered in 1880 and explored first by Mr. T. Dunkin Paret, of Stroudsburg. It was soon afterward examined by Dr. Joseph Leidy, of Philadelphia, and Dr. Thomas C. Porter, of Easton. Leidy published the first description of it in 1880 (Proc. Acad. Nat. Sci. Phila., pp. 346–348) and presented a list of the species of animals which had been secured by Mr. Paret. In 1889 (Ann. Rep. Geol. Surv. Pennsylvania, for 1887, pp. 1–18, plates I, II), a more detailed report was made by Leidy, including descriptions and illustrations of some of the vertebrates and of certain artifacts which had been discovered.

In 1894, Dr. H. C. Mercer made a re-exploration of the cave and gave a more extended description of it (Proc. Acad. Nat. Sci. Phila., pp. 96–104).

Combining the statements of Leidy and Mercer with data obtained from the Delaware Water Gap topographical sheet issued by the U. S. Geological Survey, one finds that the cave is situated on Crystal Hill, about 3.5 miles in a straight line southwest of Stroudsburg and close to the village of Stormville. Crystal Hill is a part of an anticlinal fold, Godfrey Ridge, of the Helderberg limestone. South of the fold runs Cherry Creek; north of it, Mt. Michaels Creek. On the northeast the hill is cut off from the rest of the ridge by a valley about 300 feet deep. Mercer’s account states that the cave is on the top of the hill, about 0.25 mile from Cherry Creek, but the topographical map locates the top of the hill about 0.75 mile away from this stream. Mercer also wrote that the cave was 800 feet above Delaware River, 5 miles away. However, the hill has an elevation of somewhat less than 840 feet above sea-level, while the river at the nearest point is somewhat more than 280 feet above sea-level. Inasmuch as the cave is probably somewhere on the southern slope of the hill, it is about 500 feet above the Delaware and about 300 feet above the bed of Cherry Creek.

The opening of the cave in the rock was wide (Mercer, p. 96, fig. 1), but had become almost wholly choked by débris. Nevertheless, a hole large enough for adventurous boys to enter remained (Leidy, op. cit., 1880, p. 346). After a few feet descent the cave extended nearly horizontally more than 100 feet. It had become filled nearly to the roof by various deposits. Excavations showed that on top was a layer, about a foot, of “black friable earth mingled with animal and vegetal remains” (Leidy). Mercer describes it as a “top layer of limestone roof-splinters and down-slidden outer talus thinning inward into less stony cave earth.” Beneath this layer was a thin stratum of stalagmite. Further digging showed that below this stalagmite flooring the cave was filled to a thickness of as much as 14 feet in one place. This deposit is described by Mercer as being a continuous homogeneous bed of exquisitely fine clay deposited in thin laminæ rarely sprinkled with sand pockets and underlain with a thin film of sand. Neither in this deposit nor in the stalagmite was there found a trace of any formerly living thing. All the remains of animals and all the artifacts were discovered in the uppermost layer.

It should be noted at this point that this cave is situated about 5 or 6 miles north of the Wisconsin moraine.

The following is a list of the species of vertebrates identified by Leidy. When his names differ from those now in use they are inclosed in parenthesis.

_List of species of vertebrates._

Chelydra serpentina. Terrapene carolina (Cistudo clausa). Meleagris gallopavo sylvestris (M. gallopavo). Equus sp. indet. (p. 185). Mylohyus pennsylvanicus (Dicotyles) (p. 213). Rangifer caribou (p. 246). Odocoileus virginianus (Cervus) (p. 237). Cervus canadensis (p. 237). Bison bison? (B. americanus) (p. 267). Marmota monax (Arctomys). Tamias striatus. Sciurus carolinensis. Castor canadensis (C. fiber). Peromyscus leucopus (Hesperomys). Neotoma magister (N. floridana). Microtus pennsylvanicus (Arvicola riparius). Erethizon dorsatum. Castoroides ohioensis (p. 272). Sylvilagus floridanus (Lepus sylvaticus) Myotis subulatus (Vespertilio). Eptesicus fuscus (Vespertilio). Scalopus aquaticus (Scalops). Procyon lotor. Mustela noveboracensis (Putorius ermineus). Mephitis putida (M. mephitica). Urocyon cinereoargenteus (Canis virginianus). Canis lycaon? (C. lupus). Lynx canadensis (Felis).

Besides these vertebrates, there were reported by Leidy the land snails _Helix albolabris_, _H. alternata_, and _H. tridentata_; also a pair of valves of the river mussel _Margaratina margaritifera_ and a fragment of another valve. Leidy regarded these as showing that this mussel formerly lived in Delaware River; whereas in his view it no longer existed there; but specimens of it from Philadelphia are in the U. S. National Museum.

An examination of the list shows that nearly all of the species of vertebrates are yet in existence and most of these still living in that general region. _Rangifer caribou_ lives now far to the north and _Lynx canadensis_ has its range somewhat further north. The two indicate a colder climate, especially the reindeer. Both got into the cave probably after the glacial front had withdrawn from that vicinity. The remains of _Castoroides_ may have been carried in there at about the same time. The type specimen of _Mylohyus pennsylvanicus_ was found in this cave. Cope referred specimens of a peccary found in Port Kennedy Cave to the same species with doubt. Undetermined species of the genus were recognized by Barnum Brown in his collection made in the Conard fissure in northwestern Arkansas. Dr. W. J. Holland reported _Mylohyus pennsylvanicus_ from the cave at Frankstown, Pennsylvania. The type of the genus, _M. nasutus_, was found in Indiana. Beyond the testimony furnished by the Crystal Hill Cave, we have no evidence that the genus _Mylohyus_ existed after the Wisconsin stage; the possibility exists that this species got into the cave before this stage.

The specimen of _Equus_ is still more doubtful. It consisted of two isolated first and second milk molars of a very young colt. Leidy was in doubt whether the colt belonged to the domestic horse or to an indigenous species. The specimen had been collected with no record as to the part of the cave or of the depth in the upper layer of soil where it was buried. A fragment of a jaw of a colt might easily have been carried into the cave by some carnivorous animal since the coming of the whites. A fragment of the lower jaw of a bison also was found which had in it the last molar; and this was referred by Leidy to the existing buffalo.

It can hardly be doubted that this cave was hollowed out before the Wisconsin ice period. It may have been formed during the early Pleistocene. The fact that it was filled to a depth of 14 feet, in some places, with a fine laminated clay devoid of all traces of organic beings seems to indicate that for ages it had been shut off from the outer world, and that streams charged with fine sediment were permitted to pass through it. During possibly some glacial stage preceding the Wisconsin, erosion may have opened the cave so that the horse remains, those of a bison, and of _Castoroides_ were dragged into it. The evidence for these suppositions is slender, but so too is that for a late Wisconsin indigenous species of horse in Pennsylvania. It is probable that most of the species found in the cave belong to the late Pleistocene or even to the Recent.

Fossil vertebrates found in a cave in Bucks County require our attention.

In 1880 (Proc. Acad. Nat. Sci. Phila., 1880, p. 349), Leidy presented a list of vertebrate remains which had been lying unstudied for 40 years in the collection of the Academy. These had been found in Durham Cave, somewhere near Riegelsville, in Bucks County. It is not improbable that the cave took its name from the village of Durham, about 2 miles southwest of Riegelsville. Leidy stated that the cave appeared to have been obliterated in the quarrying of limestone. In 1889 (Ann. Rep. Geol. Surv. Pennsylvania, for 1887, pp. 18–19) Leidy published a list of the species which he had identified.

_List of fossil vertebrates from Durham Cave._

Acipenser sturio. Ameiurus nebulosus (Amiurus atrarius). Thamnophis sirtalis (Eutænia). Chelydra serpentina. Terrapene carolina (Cistudo clausa). Meleagris gallopavo sylvestris (M. gallopavo). Rangifer caribou (p. 246). Cervus canadensis (p. 237). Alces americanus (Alce). Odocoileus virginianus (Cervus) (p. 227). Erethizon dorsatum. Marmota monax (Arctomys). Sciurus carolinensis. Castor canadensis (C. fiber). Neotoma pennsylvanica (N. floridana). Ondatra zibethica (Fiber). Sylvilagus floridanus (Lepus sylvaticus). Ursus americanus. Procyon lotor. Mephitis putida (M. mephitica). Urocyon cinereoargenteus (Vulpes virginianus).

This list differs in its species from Leidy’s list of 1880 only in the exclusion of the bison and the inclusion of the elk, _Cervus canadensis_. All the species are still in existence, most of them in that region. The presence of the reindeer, the moose, and the porcupine suggests a cooler climate than now prevails there. These animals may all have become buried in that cave during the latest times of the Wisconsin stage or even during the Recent.

We are now to study a case which furnishes us with a store of knowledge regarding the life of the Pleistocene. In 1871 there was found at Port Kennedy, Montgomery County, a cave which was worked for its fossils by Charles Wheatley and later by Dixon, Mercer, and Cope, the latter having devoted himself to the description of the vertebrates. First of all will be given a list of the species of vertebrates, mostly mammals which have been recognized in the materials found in the cave. When Cope’s names differ from those employed here they are put in parenthesis.

_List of species of vertebrates found in Port Kennedy Cave._

Ranidæ:
Rana sp. indet.
Emydidæ:
Clemmys insculpta.
C. percrassa.
Terrapene eurypygia (Toxaspis anguillulatus).
Colubridæ:
Coluber acuminatus (Zamenis).
Meleagridæ:
Meleagris superbus (M. altus).
Megatheriidæ:
Megalonyx (p. 31).
M. scalper (p. 31).
M. tortulus (p. 31).
M. wheatleyi (p. 31).
Mylodon harlani? (p. 31).
Equidæ:
Equus complicatus (E. fraternus) (p. 185).
E. pectinatus (E. f. pectinatus) (p. 185).
Tapiridæ:
Tapirus haysii (p. 203).
Tagassuidæ:
Mylohyus nasutus (p. 213).
M. pennsylvanicus? (p. 213).
Tagassu tetragonus (Mylohyus) (p. 213).
Camelidæ?:
Teleopternus orientalis (p. 224).
Cervidæ:
Odocoileus lævicornis.
O. virginianus?
Bovidæ:
Bison sp. indet. (Bos) (p. 256).
Elephantidæ:
Mammut americanum (Mastodon) (p. 69).
Sciuridæ:
Sciurus calycinus.
Castoridæ:
Castor canadensis (C. fiber).
Cricetidæ:
Peromyscus leucopus? (Hesperomys).
Anaptogonia hiatidens.
Sycium cloacinum.
Microtus dideltus.
M. diluvianus.
M. involutus.
M. speothen.
Zapodidæ:
Zapus hudsonius?
Erethizontidæ:
Erethizon dorsatum?
Ochotonidæ:
Ochotona palatina (Lagomys).
Leporidæ:
Sylvilagus floridanus (Lepus sylvaticus).
Talpidæ:
Scalopus sp. indet. (Scalops).
Soricidæ:
Blarina simplicidens.
Vespertilionidæ:
Myotis? sp. indet. (Vespertilio).
Ursidæ:
Ursus americanus.
Arctotherium haplodon.
Mustelidæ:
Taxidea taxus (T. americana).
Mephitis fossidens.
M. leptops.
M. obtusata.
M. orthostica.
M. putida.
Osmotherium spelæum.
Pelycictis lobulatus.
Mustela diluviana.
Gulo luscus.
Lutra rhoadsii.
Canidæ:
Canis priscolatrans.
C. dirus? (C. indianensis).
Urocyon cinereoargenteus.
U. latidentatus.
Felidæ:
Machairodus gracilis.
Smilodontopsis mercerii (Smilodon).
Felis eyra.
F. inexpectata (Uncia).
Lynx calcaratus.

Into this list there are admitted 60 species, of which 54 are mammals. Of these, 41 are extinct, not counting the doubtful species unless there is good reason for it. There are, therefore, 68 per cent of the species extinct.

No remains of _Rana_ were mentioned by Cope in his list of 1899. One species unnamed was recorded by Wheatley in his lists of 1871 and by Mercer in his paper of 1899. The turkey (_Meleagris superbus_) was not included by Cope in 1899, but it was included by Wheatley and Mercer and Cope in their papers of 1871 and in that of Cope in 1896 (p. 378). Mercer (1899, p. 280) mentions a leg-bone of a turkey, with spur, found by Wheatley. Remains of _Megalonyx_ were abundant, but of _M. loxodon_ only a single tooth was met with. _Mylodon_, believed to be _M. harlani_, was found only by Wheatley and was represented, as stated by Cope, by only a claw phalanx. The horse remains were originally (Cope, 1895, p. 447) referred to _Equus major_ (=_E. complicatus_). Mercer, in 1899, in his figure 9, following Cope’s nomenclature, uses the name _E. complicatus_. In 1899, Cope concluded that the equine remains represented two races of _Equus fraternus_, _E. f. fraternus_ and _E. f. pectinatus_. The present writer believes that the teeth referred to the subspecies _fraternus_ are too large to belong to the species which was called _E. fraternus_, but which is now called _E. leidyi_. Only a single species of tapir, _Tapirus haysii_, was recognized. Cope (1895, p. 447) stated that it was the most abundant of the larger mammals. Cope (1899, p. 257) reported that 18 individual peccaries were represented by teeth, while bones were numerous. He recognized the presence of three species. The identifications of _Mylohyus nasutus_ and _M. pennsylvanicus_ were uncertain. A new species, _M. tetragonus_, was based on a ramus of a lower jaw. Milk molars were yet present and the third molar had not appeared. Cope spoke of the long diastema; but, to judge from his figure, the diastema equals only about the length of the milk molars and the first molar.

Cope, in 1899, described _Teleopternus orientalis_, basing it on a few teeth which belonged to three individuals. He was doubtful about the family position of the animal, but put it provisionally in the Camelidæ. In many respects the teeth resembled those of the Cervidæ. Matthew (Osborn, Age of Mammals, p. 469) has suggested its affinity to _Ovibos_.

Two species of deer were found in the cave, of which one was not distinguishable from _Odocoileus virginianus_. In Wheatley’s second list of 1871 and that of Cope of the same year there was recorded an undetermined species of _Bos_ (_Bison_). Mercer (1899, p. 280) recorded from the Wheatley collection remains of three individuals of one species of the same genus. In Cope’s paper on the remains of this cave nothing is said about the genus; but in 1872 (Proc. Amer. Philos. Soc., XII, p. 96) he stated that _Bos_ was represented by a part of a femur and some other bones. Hence in the list given above an undetermined species of _Bison_ is included.

Abundant remains of the mastodon occurred in the cave, but none of any of the elephants. One need not, however, on that account conclude that elephants were not living in that region at that time.

It will be observed that a considerable number of rodents is included in the list. One species of porcupine is recognized. This was at first regarded by Cope as an extinct form and called _Erethizon cloacinum_; but in 1899 he referred all the remains, with some doubt, to the existing species, _E. dorsatum_. Cope found remains of about 50 individuals of a species of rabbit which he determined as _Lepus sylvaticus_, but this is now called _Sylvilagus floridanus_. In the Wheatley collection a species of bat was recognized and put in _Vespertilio_. Probably it belonged to _Myotis_.

Bears were abundantly present in the cave. One species, _Arctotherium haplodon_, was larger than the grizzly bear and represented by parts of about 25 individuals. A smaller bear, indicated by 8 individuals, appeared to be in no way different from the existing black bear, _Ursus americanus_. Of skunks there are listed 7 species, belonging to 3 genera, all the species being extinct except a supposed _Mephitis putida_. Besides these mustelids, there have been identified remains of the existing badger, the existing glutton, an extinct weasel, _Mustela diluviana_, and an extinct otter, _Lutra rhoadsii_. Remains of true dogs were not abundant in the collection. Cope recognized, however, 2 species of the genus _Canis_, one of about the size of the more common form of the existing wolf; the other exceeding in size the largest wolf known to him. This he thought might belong to Leidy’s _Canis indianensis_ (=_C. dirus_ Leidy). There were present 2 foxes, the existing gray fox (_Urocyon cinereoargenteus_) and an extinct species, _U. latidentatus_. Of the cat family a species, thought at first to be a hyæna (_Crocuta_), received the name _Felis inexpectata_. It had the size of the jaguar, and was represented by teeth and various bones. An extinct lynx, much like _Lynx ruffus_, was present. Another cat was identified as _Felis eyra_. Of this species G. S. Miller (Bull. 79, U. S. Nat. Mus., p. 116) remarks that its type locality is Paraguay and that it is supposed to range north to Central America. It appears somewhat doubtful, therefore, that the fossil remains belong to this species. Nevertheless, the progenitors of the species, in their wandering from Asia or Alaska to Central America and Paraguay, might have sent a colony into Pennsylvania, later to become extinct. Cope stated (1899, p. 250) that there was an isolated calcaneum in the collection which was of the proper size for _Felis eyra_, but which differed from that of this species. Two species of saber-tooth cats were found, _Smilodontopsis gracilis_ and _S. mercerii_. The former is represented by various bones and teeth, especially by a damaged skull which presents the dentition. The crown of the great canine is 113 mm. long.

Besides the species included in the list given above, there are a few whose presence for one reason or another is doubtful. In both of his lists of 1871 Wheatley reported the presence of _Crotalus_, _Coluber_, and _Tropidonotus (Natrix)_. Cope (1871, p. 98) said that the reptiles included three or four serpents, but in 1895 (p. 447) he wrote that two species of _Ophidia_ were recognized. In his final paper he mentioned only his _Zamenis acuminatus_, here referred to _Coluber_. Wheatley (1871, p. 255) recorded an unidentified snipe as belonging to _Scolopax_. Cope (1871, p. 98) wrote that a snipe was one of two species of birds present. Mercer (1889, p. 280) recognized the same remains as belonging to a species of _Gallinago_. Wheatley in his last list (1871, p. 384) and Cope (1871, p. 98) reported _Scalopus (Scalopus)_ as being represented by an undetermined species. It is catalogued by Mercer in the same way. Cope (1895, p. 447) stated that the raccoon was very rare; but it was not mentioned in any of his later papers. On the same page he wrote that there were fragments of teeth closely similar to those of _Bassariscus astutus_; but the species was not mentioned afterward.

As already said, there are admitted into the list given above, as identified in a reasonably good manner, 60 species, of which 54 belong to the Mammalia. It is a matter of interest to compare these with the species of mammals which were living in that general region before the fauna was disturbed by the arrival of the whites. The number of species of the existing mammals, as shown in the second column, is obtained from Rhoads’s “Mammals of Pennsylvania and New Jersey.” The subspecies are not included.

_Families of land mammals represented in Port Kennedy Cave and those
that have lived in that region within Recent times, together with the
number of known species in each family at each of the two epochs._

┌──────────────────────┬──────────────────────┬──────────────────────┐ │ Families. │ No. of species, Port │ │ │ │ Kennedy. │No. of recent species.│ ├──────────────────────┼──────────────────────┼──────────────────────┤ │Megatheriidæ │ 5│ │ │Didelphidæ │ │ 1│ │Equidæ │ 2│ │ │Tapiridæ │ 1│ │ │Tagassuidæ │ 3│ │ │Camelidæ? │ 1│ │ │Cervidæ │ 2│ 2│ │Bovidæ │ 1│ 1│ │Elephantidæ │ 1│ │ │Sciuridæ │ 1│ 6│ │Castoridæ │ 1│ 1│ │Cricetidæ │ 7│ 9│ │Zapodidæ │ 1│ 2│ │Erethizontidæ │ 1│ 1│ │Ochotonidæ │ 1│ │ │Leporidæ │ 1│ 2│ │Soricidæ │ 1│ 5│ │Talpidæ │ 1│ 3│ │Vespertilionidæ │ 1│ 8│ │Procyonidæ │ ?│ 1│ │Ursidæ │ 2│ 1│ │Mustelidæ │ 11│ 9│ │Canidæ │ 4│ 3│ │Felidæ │ 5│ 3│ └──────────────────────┴──────────────────────┴──────────────────────┘

In the column of fossils there are 54 species; in that of the Recent there are 58 species. Of two families represented at present in the region, but not included in the Pleistocene column, Didelphidæ and Procyonidæ, the latter named has had remains referred to it with doubt. Without doubt members of both families existed there at that time.

Of the families of the Pleistocene column two no longer live anywhere near the region; four nowhere on the continent; one nowhere on the earth. Even of such families as the Ursidæ and the Felidæ important elements, as _Arctotherium_ and the saber-tooths, are extinct. Of the 54 species admitted in the Pleistocene column 40 are extinct; that is, 74 per cent.

If we consider the sizes of the animals in question we gain this result: Only 15 of the existing species are of any considerable size, ranging from that of a raccoon to that of a bison, about 26 per cent. Of the 54 fossil species of mammals, about 30 vary in size as indicated, about 57 per cent. It is hardly to be doubted that this preponderance is due to the poorer chances which the smaller skeletons had of preservation and of rescue from the matrix. Had the smaller fossil species been preserved and collected in the same proportion that the smaller existing ones have to the larger, the cave ought to have furnished twice as many species of mammals as it did. It is, of course, possible that the larger species are more liable than the smaller ones to become extinct as time passes on. We can hardly doubt, in any case, that when the Port Kennedy animals were being buried in that cave there lived in that region a considerably larger number of species than within Recent times. There must have existed in that region more moles, more rabbits, more cricetids, more squirrels, and many more bats. Certainly there is no adequate record of the number of birds, snakes, turtles, and amphibians that must have existed about Port Kennedy and have perished in that cave.

From the collection that has been made in the cave at Port Kennedy some definite conclusions ought to be reached regarding their time of existence. In his account of the cave and of the exhumation of the animal and vegetable remains, Mercer (1899, pp. 269–286) has shown what extreme care was taken in recording the position which each specimen occupied in the deposits. In his figure 9 he has noted the levels which the various species occupied. While the existence of four beds of materials makes it evident that the deposition went on for some time, it is noted that few or no differences exist in the character of the species included. Possibly Mercer’s subdivision 1 is to be excepted in this statement. Certainly no great changes went on in the fauna while the cave was being filled; no such changes as occurred in the glaciated region from the Aftonian interglacial stage up to the Late Wisconsin. It appears more probable that the deposits in the cave and the animals entombed there appertain to about a single Pleistocene stage. Is, then, the stage the Late Wisconsin?

This cave is situated only about 55 miles south of the Wisconsin moraine. At the time the species found in the cave existed they must each have occupied a wide extent of territory. It is not to be doubted that the range of nearly every species extended northward far beyond the moraine mentioned. Why, then, in deposits overlying the Wisconsin drift have there never been found any remains of the four Port Kennedy species of _Megalonyx_, of _Mylodon_, of the two species of horses, of the tapir, of the three species of peccaries, of the deer _Odocoileus lævicornis_, of the five extinct species of cricetids, of _Ochotona_, of the extinct species of _Blarina_, of the great bear _Arctotherium_, of the six extinct species of skunks, of the extinct otter, of the extinct dog, of the extinct fox, of any species of saber-tooth tiger, or of the extinct cats _Felis inexpectata_ and _Lynx calcaratus_? The absence of so many species of animals, most of them of large size, from deposits so well adapted to preserve bones and teeth, render it very certain that the animals no longer existed there.

Did the extinct species which are referred to above exist in eastern Pennsylvania at some time during the Wisconsin glacial stage and perish before the close?

A few of the species found in the cave and still existing are at present inhabitants of regions somewhat more northerly than Port Kennedy. Such are _Erethizon dorsatum_ and _Gulo luscus_; but the great majority, living and extinct, indicate a climate at least as warm as that of the present; many of them suggesting a still milder condition. Within historical times both of the species just named have inhabited the Alleghany Mountains at least as far south as Port Kennedy. Cope, in 1871 (Proc. Amer. Philos. Soc., vol. XII, p. 99), concluded that he had then identified in the cave remains of 11 neotropical species. It appears, therefore, wholly improbable that this assemblage of animals lived in that region, so close to the foot of the glacier, during the Wisconsin stage. These animals must have had their time of existence previous to this inhospitable epoch. It seems to the writer that the proportion of extinct species, three-fourths, and the history of many of the genera and species, indicate a time about equivalent to the Aftonian.

Professor A. Heilprin (Proc. Phila. Acad. Nat. Sci., 1895, p. 451) expressed himself as being inclined to refer this cave fauna to the Pliocene. An examination of this opinion would show that it is no more tenable than the opinion that the fauna is of the Wisconsin stage. It will not be discussed here beyond saying that deposits containing a similar fauna are found along the Atlantic coast from New Jersey to the Gulf, and that at one place at least, Vero, Florida, these are underlain by abundant Pleistocene sea-shells.

Besides the vertebrates which have been listed, a number of beetles were found and about 10 specifically determined plants. Wheatley (1871, p. 385) presents a list of the beetles as determined by Dr. G. H. Horn, but the names were not accompanied by descriptions. When later (Trans. Amer. Entom. Soc., vol. V, 1876, pp. 241–245) Horn came to describe them he reduced the number of species and, in some cases, gave them other names. The following is a list as given in Horn’s paper just cited: _Cychrus wheatleyi_, _C. (minor)_, _Pterostichus_ (spp. indet.) _Cymindis aurora_, _Chlænius punctulatus_, _Dicælus alutaceus_, _Choeridium? ebeninum_, _Phanæus antiquus_, _Aphodeus precursor_. All of these, as the writer is informed by Dr. E. A. Schwarz, of the U. S. Department of Agriculture, are regarded as extinct, but as closely allied to species now living in that general region. The plants, as reported by Mercer, are _Quercus palustris_, _Q. alba_, _Q. macrocarpa_, _Fagus ferruginea_, _Corylus americana_, _Pinus rigida_, _Carya porcina_, _C. alba_, _Ampelopsis quinquefolia_, _Cratægus crus-galli?_, and all still flourish in eastern Pennsylvania.

FIG. 11.—Section of Port Kennedy bone cave at time of first
exploration, 1871. Redrawn from Mercer.

M, M, Triassic shale; AL, Triassic shale; B, black clay, with leaves,
etc.
]

Mercer (1899, p. 269) has given a description of the cave found in quarrying operations. It was located on the right bank of the Schuylkill River, at the village of Port Kennedy and about 2 miles below Valley Forge. Wheatley (1871, p. 236) gave a map which showed the position of the quarries. A comparison of this with the topographical map of Folio 162 of the U. S. Geological Survey shows that they were situated about 800 feet away from the river and facing the valley of an unnamed streamlet. None of the descriptions give the elevation of the cave above the river or above the sea. The river at that place is apparently about 70 feet above sea-level. The 100–foot contour-line runs along near the location of the quarries, but these may have extended back to a higher level. Putting all of the statements together, it appears probable that the mouth of the cave was, in Wheatley’s time, about 50 feet above the level of the river. Originally the surface elevation may have been still greater, but may have been reduced by erosion of the hill. The surface rock here is red shale of the Stockton formation, belonging to the Triassic, and is underlain by the Shenandoah limestone, a member of the Cambro-Ordovician series. This limestone was being quarried in 1871, when a cave was broken into, filled with incoherent materials and exposing fossil bones in abundance. It was visited by Charles Wheatley, who proceeded to make excavations and collect the fossils. In studying the fossils he worked with Professor E. D. Cope and Dr. G. H. Horn. The results were published in Wheatley’s two papers of 1871 and in two papers by Cope in the same year (Proc. Amer. Philos. Soc., vol. XII, pp. 15, 73–102). According to Wheatley’s description and his figures, the part of the cave seen was about 20 feet wide at the top, expanded below to about 30 feet, and then narrowed at the bottom, as then recognized, to about 10 feet. The depth was given as 40 feet, but Mercer thinks that this was improbable and that Wheatley’s measurements were to some extent guesses. Mercer (1899, p. 271) stated that this cave might be compared to a bottle of unknown size. It had opened to the surface; and on his page 283 Mercer spoke of it as forming a well-like hole that might have been as much as 70 feet deep. Evidently Mercer here included that part of it which he himself excavated. The materials filling it were, according to Cope (1871, p. 73), the débris of the neighboring Triassic strata. Figure 11 is taken from Mercer’s paper and is a reproduction of a sketch made by Wheatley in 1871. After Wheatley had made his collection the cave was covered over by débris from the quarry and forgotten.

FIG. 12.—Section of Port Kennedy bone cave at time of last
exploration, 1894. Redrawn from Mercer.
]

In the course of further quarrying operations the same cave was broken into again in 1893. Excavations in the materials that filled the cave were made in 1894 by Dr. Samuel Dixon, H. C. Mercer, and others, resulting in the securing of the collection which formed the subject of Cope’s paper of 1894 and his final report of 1899. At this time, according to Mercer, the quarrying operations carried on from 1855 had transformed a gently sloping hillside into an amphitheater several acres in extent, walled with perpendicular escarpments of rock, sometimes a hundred feet high. At this time the floor of the quarry had been lowered and the cave was broken into at a level below that reached by Wheatley. Figure 12, reproduced from Mercer’s figure 5, shows the relation of the later excavations to those of 1871. As already stated, Mercer concluded that Wheatley’s dimensions were probably results of guesses, inasmuch as the top of Mercer’s exposure was not more than 30 or 33 feet below the original level of the hilltop. According to Mercer’s figure 5, his own excavation probably extended down about 16 feet below the level reached by Wheatley; but other statements appear to make this somewhat greater.

Mercer wrote that the materials filling the cave had been stratified by the action of water. He recognized four subdivisions, most of which stood higher around the walls than at the center of the cave. Of these subdivisions, the first and uppermost was supposed to mark the lowest level attained by Wheatley. It consisted of fine clay and loam of black color, intermingled with fine and coarse muck, in which were found some remains of small mammals, just what species was not stated. On his chart, his figure 9, a tapir is indicated as occurring in it. Subdivision 2 was composed of from 4 to 11 feet of sandy clay, with fragments of sandstone and limestone, from small ones up to about 2 feet in diameter. In this matrix there were numerous bones and teeth of large animals, but it lacked small ones and vegetal matter. Subdivision 3 was a sandy clay, blackened by vegetable matter and containing numerous bones of vertebrates, large and small. The lowest subdivision, 4, was a zone which was followed down about 10 feet and which consisted of sand, clay, and stones, all of a yellow color. In this were found remains of the larger mammals, better preserved than in the upper subdivisions. At the lowest depth reached the excavation appears to have extended below the level of the Schuylkill River and the water came in so rapidly that further descent was not practicable.

Mercer’s theory of the filling of the cave is expressed in these words, on his page 277:

“Enough had been seen to convince us that a fresh-water flood,
rising to a level of from 15 to 20 feet above the present level of
the hilltop, hence a general inundation of the whole surrounding
country, bearing in its current the clay, stones, and earth of
neighboring levels, had tumbled into the fissure, carrying with it
the bones of creatures previously denuded of flesh and softened by
decomposition.”

And further, on page 284:

“Not unreasonably, therefore, we may suppose, not only that the
creatures had perished together, but also that they had perished on
the spot or at the chasm—not meeting this fate during a long
interval of time, and through a long series of chance tumbles, but
suddenly and by force of a common event.”

Are we to suppose that during some summer freshet animals in such numbers were swept away that those that were found in the cave, and doubtless many more which decayed utterly, were only the relatively few that happened to pass over that 20–foot hole? Where, then, were picked up all the other animals that must have burdened the swollen Schuylkill? Or did it possibly happen that all the animals that were swept away were in some unaccountable manner directed into that hole? If the current was strong enough to sweep along stones up to 2 feet in diameter, how did it happen to deposit there fine sand and clay, leaves, cones, seeds, and sticks? It is difficult to accept the theory that the filling of the cave was due to a cataclysm such as has been invoked. It seems far more probable that the mouth of the cave was open for many hundreds of years, possibly thousands of them, so that animals, plants, stones, and fine and coarse earth could in various ways get into it. Animals wandering about might inadvertently fall in or be pushed in by the herd. Doubtless at some former time the Schuylkill flowed at a higher level than now, and during times of unusually high-water might have risen to the level of the mouth of the cave and carried into it at each rise some mud, some vegetation, and some animals. The filling was quite certainly a slow process.

To the writer the part of the cavern which was worked and pictured by Wheatley has all the marks of an enormous pot-hole, such as those which have been discovered at Cohoes, New York. While the latter appear to have been drilled out in late Pleistocene times, the Port Kennedy hole must have been fashioned during the early Pleistocene or even in the Pliocene. One may suppose that, after the pot-hole had reached the depth where the constriction was found, the water began to find its way out at the bottom through fissures or passages in the limestone. When this happened, the passages may have been enlarged mechanically or by means of solution, resulting in the formation of the various lower caverns. When the river had been lowered enough to reach only occasionally the mouth of the pot-hole, the latter became choked first by the coarse materials now found in subdivision 4, and afterwards by finer sand and mud.

Some vertebrates of the late Pleistocene or early Recent observed at Carlisle deserve consideration.

In 1850 (Proc. Amer. Assoc. Adv. Sci., vol. II, 1849, pp. 352–355) Professor S. F. Baird gave an account of his explorations in the caves in the region about Carlisle, Cumberland County. One of these caves was near Carlisle, and in it Baird found a large number of animal remains. A second cave, the situation of which was not given, was on the top of a hill and was a vertical shaft 30 feet deep, which opened into a large gallery. It furnished a skeleton of a bear, but this appeared to have only recently fallen into the cave. Another cave was on the bank of the Susquehanna, 0.5 mile below a railroad bridge. It was, therefore, probably near Harrisburg. The entrance was in limestone rock, nearly vertical, and 20 feet deep. Here Baird found many bones, embedded in mud, but of these he obtained only a few. Another cave, apparently nearby, which Baird spoke of as “the main cave,” furnished some of his specimens. Still another cave, probably in the same neighborhood, was the source of his most perfect specimens. This presented a series of galleries near the roof and these were reached by ladders. These galleries were filled with mud, and in this mud the bones were buried. The number of species which he obtained, he reported, was nearly twice the number living there at the present time. Of these fossil species he estimated that about 5 per cent were extinct. Baird appears never to have completed his study of his collection. His list designates the animals only by their vernacular names. The mammals consisted of panthers, lynxes, wolves, foxes, otters, bears, muskrats, deer, beavers, and rabbits. There were bird remains in great quantities, and these included wild turkeys, some of great size, swans, wild ducks, and pelicans. There appeared to be 8 or 10 species of tortoises. Bones of snakes were quite common; also scales and vertebræ of fishes, and a lower jaw of a salamander. In the uppermost 2 or 3 inches of mud were many relics of Indians.