Chapter XVII: On the Theory of the Pleistocene Terraces of the Coastal Plain (20)

An interesting list of Late Wisconsin mammals has been secured near Whitewillow, Kendall County. From Dr. E. S. Riggs, of Field Museum of Natural History, and from Netta C. Anderson’s list, the writer learns that at least six skulls of the common mastodon, together with many other parts of the skeleton, has been taken from a well 10 feet in diameter (p. 109). Above, there were bones of bison (p. 269), deer (p. 229), and elk (p. 240). It is stated that a layer of these about 2 feet thick was encountered at a depth of about 5 feet.

Mr. George Langford, of Joliet, states that he made a collection of bones 15 miles west of Joliet and 5 miles west by north of Minooka. The more exact locality he gave as township 35 north, range 8 east, and probably section 27, on the farm of John Bamford. Apparently both Riggs and Langford obtained their materials at the same spot. The latter has sent the writer some bones from this place, including those of _Cervalces_, _Alces americanus_, and a leg-bone of some undescribed species of sheep or goat. He also reported the finding of the elk. For other remarks see page 269. This locality is in the region mapped by Leverett as having been occupied, after the retirement of the Wisconsin glacial ice, by temporary lakes. The presence of the moose here seems to indicate a climate somewhat severer than that now prevailing in that region. Since the occupancy of the country by the European race the moose has not been known to come further south than northern Wisconsin. The list of species obtained is as follows: _Mammut americanum_, _Ovis_ sp. indet., _Odocoileus virginianus_, _Cervus canadensis_, _Alces americanus_, _Cervalces roosevelti?_.

A brief description of the bone referred to _Ovis_ is presented. The lower epiphysis is missing, but an allowance is made for this (fig. 13).

_Comparisons of the metatarsals of a sheep, of a goat, of Næmorhedus,
and of Orvis sp. from Whitewillow, in millimeters, together with
indices in one-hundredths of the length._

┌──────────────┬───────┬─────╥───────┬─────╥──────┬─────╥───────┬─────┐ │ Measurements │ │ ║ Capra │ ║ │ ║White- │ │ │ taken. │ Næmo- │Indi-║hircus │Indi-║ │Indi-║willow │Indi-│ │ │rhedus.│ces. ║155623.│ces. ║Sheep.│ces. ║animal.│ces. │ ├──────────────┼───────┼─────╫───────┼─────╫──────┼─────╫───────┼─────┤ │Length on │ │ ║ │ ║ │ ║ │ │ │ outer border│ │ ║ │ ║ │ ║ │ │ │ of bone │ 170│ 100║ 120│ 100║ 152│ 100║ 185±│ 100│ │Side-to-side │ │ ║ │ ║ │ ║ │ │ │ width of │ │ ║ │ ║ │ ║ │ │ │ upper │ │ ║ │ ║ │ ║ │ │ │ articular │ │ ║ │ ║ │ ║ │ │ │ surface │ 36│ 21.2║ 23│ 19.2║ 23│ 15.1║ 37.5│ 20.3│ │Fore-and-aft │ │ ║ │ ║ │ ║ │ │ │ width of │ │ ║ │ ║ │ ║ │ │ │ upper │ │ ║ │ ║ │ ║ │ │ │ articular │ │ ║ │ ║ │ ║ │ │ │ surface │ 30.5│ 17.4║ 20│ 16.7║ 21│ 13.8║ 37.5│ 20.3│ │Side-to-side │ │ ║ │ ║ │ ║ │ │ │ width, at │ │ ║ │ ║ │ ║ │ │ │ middle of │ │ ║ │ ║ │ ║ │ │ │ length │ 23│ 13.5║ 15│ 12.5║ 14│ 9.2║ 19.0│ 10.3│ │Fore-and-aft │ │ ║ │ ║ │ ║ │ │ │ width at │ │ ║ │ ║ │ ║ │ │ │ middle of │ │ ║ │ ║ │ ║ │ │ │ length │ 17.5│ 10.3║ 11.5│ 9.1║ 13│ 8.6║ 20.0│ 10.8│ │Side-to-side │ │ ║ │ ║ │ ║ │ │ │ width at │ │ ║ │ ║ │ ║ │ │ │ lower end │ │ ║ │ ║ │ ║ │ │ │ just above │ │ ║ │ ║ │ ║ │ │ │ epiphysis │ 38│ 22.4║ 27│ 22.5║ 27│ 17.8║ 35.0│ 19.5│ │Side-to-side │ │ ║ │ ║ │ ║ │ │ │ width across│ │ ║ │ ║ │ ║ │ │ │ lower │ │ ║ │ ║ │ ║ │ │ │ articular │ │ ║ │ ║ │ ║ │ │ │ surface │ 41│ 24.1║ 27.2│ 22.5║ 25│ 16.4║ │ │ └──────────────┴───────┴─────╨───────┴─────╨──────┴─────╨───────┴─────┘

FIG. 13.—Metatarsal of undetermined species of Ovis? From Kendall
County, Illinois.
]

From Alton, the U. S. National Museum has come into possession of a collection which furnishes 15 species of fossil mammals. This was made some time before 1883 by Hon. William McAdams, of Alton. It was briefly mentioned by him at the Minneapolis meeting of the American Association for the Advancement of Science in 1883 (Proceedings, vol. XXII, p. 268). Apparently the collection was secured for the U. S. Geological Survey by Professor O. C. Marsh and remained at Yale University until after his death. The species were described by the writer in 1920 (Proc. U. S. Nat. Mus., vol. LVIII, pp. 109–117). This collection seemed especially valuable because the species were found inclosed in supposed nodules of loess. In our country the loess has furnished few such remains. The following is the list of the species as determined. Those marked by a dagger are extinct.

†Megalonyx jeffersonii (p. 33). †Equus sp. indet. (p. 187). †Platygonus cumberlandensis? (p. 219). †Sangamona fugitiva. †Cervalces roosevelti?. †Rangifer muscatinensis? (p. 246). †Taurotragus americanus. †Symbos cavifrons (p. 254). †Bison sp. indet. (p. 259). †Mammut americanum (p. 102). Castor canadensis. Marmota monax. †Castoroides ohioensis (p. 279). Geomys bursarius. Ursus americanus.

Of these 15 species at least two-thirds are now extinct. This large number might appear to indicate that the time of their existence was rather early in the Pleistocene. However, it is quite certain that the loess belongs somewhere about the middle of the Pleistocene; and there are no species that require an earlier date.

After the writer’s descriptions of the fossils had been published, an important paper on the geology of the locality was issued (Jour. Geol., vol. XXIX, 1921, pp. 505–514) by Professor Morris M. Leighton, who had been commissioned by the Illinois Geological Survey to visit and study the deposits involved. With the aid of Mr. John D. Adams, son of the collector of the mammalian fossils, Professor Leighton succeeded in finding the quarry in which most of the fossils had been collected.

At one quarry in Alton Professor Leighton obtained the following geological section, the description of which is here somewhat abridged:

_Feet._ Soil loessial, dark brown, leached 1 Loess, brown above, grading below into buff, leached 4 to 5 feet, maximum thickness 20 Loess distinctly more reddish than that above; many fossil snails, thickness about 30 Glacial till, reddish, with pebbles of Canadian rocks; more oxidized than overlying loess; thickness 1–3 Mississippian limestone, about 100

The concretions which hold the mammalian fossils were found to lie between the upper surface of the till and the overlying loess; occasionally a concretion bears a drift pebble. The concretions have resulted from the lime which in solution was brought down from the loess and again precipitated so as to cement the loess materials around the fossils.

Professor Leighton was not able to determine definitely the ages of the till and of the two deposits of loess. As to the till, its geographic location suggested that it belonged to the Illinoian, but it had many of the characteristics of the Kansan. The latter is believed to be present at St. Louis and other localities not far away. Before the overlying reddish loess had been deposited the till had suffered weathering and erosion, indicating a considerable lapse of time had intervened. The lower reddish loess presented many evidences that it is a deposit distinct from the upper buff loess; and there seemed to be some indications of at least a short interval between them. Leighton’s conclusion was as follows:

If the drift is Kansan in age, the reddish loess may be Sangamon; if, on the other hand, the drift be Illinoian, the reddish loess probably is Peorian. It is unlike any Peorian loess of which the writer knows, but the color does not necessarily preclude that possibility.

As to the upper loess, Leighton thought it might be of early Peorian age, but possibly of early Wisconsin. However, his final conclusion was thus expressed:

“If the till proves to be Kansan in age, the weathering of the drift
may be credited to the Yarmouth interglacial epoch, the mammalian
fauna to late Illinoian or early Sangamon times, the reddish loess
probably to the Sangamon, and the buff loess to the Iowan....
However this may be, the Illinoian and Sangamon epochs are
post-mid-Pleistocene from the standpoint of duration of the
Pleistocene and the fauna represented by the McAdams collection may
be regarded as post-mid-Pleistocene.”

WISCONSIN.

The greater part of this State is covered by the drift-sheet which has derived its name from the State, but in the southwestern corner is a considerable tract which has never been subjected to glacial action. A small part of this area extends southward into Illinois and another part into northeastern Iowa. In Wisconsin it reaches eastward to Baraboo. East of this driftless area is a tract lying along the southern border of the State and reaching eastward about to 88° 40′ longitude, which is covered by the Illinoian drift.

The most detailed geological survey of any part of Wisconsin, so far as regards the Pleistocene, is that made by Dr. W. C. Alden, of the U. S. Geological Survey, of the area comprised between the boundary of the State on the south and 44 degrees of latitude on the north and between Lake Michigan on the east and 90 degrees of longitude on the west. On the western side it joins the Mineral Point Quadrangle, to be mentioned further along. There is, therefore, a wide strip surveyed across the whole State. The area treated by Alden is, of course, nearly entirely covered by Wisconsin drift. In the southwestern corner a considerable part of the driftless region is included. East of this, as already stated, is a tract which the Wisconsin ice-sheet did not reach and which shows Illinoian ground moraine and some terminal moraines of Illinoian drift. This narrows as it approaches its eastward limit.

Alden (p. 166) informs us that at no place in the area subjected to vigorous glaciation by the Wisconsin ice-sheet had soils or vegetal deposits been found between the Wisconsin drift and the earlier drifts. At several places, however, deposits have been discovered which probably belong to earlier glacial stages. Just outside the area mapped by Alden, in Calumet and Outagamie Counties, Lawson (Bull. Wis. Nat. Hist. Soc., vol. II, pp. 170–173) has recorded the discovery of much wood and other vegetable matter. Baker (“Life of the Pleistocene,” p. 317) has referred the deposits to the Sangamon. These interglacial deposits of uncertain age need not be here noted further. In this Wisconsin area some remains of mastodons and elephants have been met with, but all are relics of a time after the partial or complete recession of the Wisconsin glacier. Remains of two individuals of _Elephas primigenius_ have been found in Milwaukee (p. 143). It is evident that they lived there after the withdrawal of the Wisconsin ice-sheet. One of these was buried beneath peat and clay at a depth of 10 feet or more and at a level of about 100 feet above the present level of Lake Michigan.

At Dover, in Racine County, in 1878, a proboscidean tusk and some bones were found in a peat-bog. They have been identified as those of a mastodon, but of this one can not be certain. The age of the deposits is that of the Late Wisconsin stage, after the withdrawal from that vicinity of the ice, but how long after one can not say. The Milwaukee Public Museum has a tooth of a mastodon (p. 111), labeled as found at Waukesha. Its geological age is that of the other remains here referred to. In the collection of the University of Wisconsin is a large vertebra of a proboscidean which was found in Lake Monona. Its time of burial must have been late Wisconsin. Inasmuch as no remains of vertebrate animals have yet been found in Wisconsin, in the area covered by the Illinoian drift, it is not necessary to dwell on this region. It is not certain that there is beneath it a still older drift; but there are, according to Alden, some indications of such deposits.

For a knowledge of the driftless area, first of all, may be consulted the report made by Chamberlin and Salisbury in 1885 (6th Ann. Rep. U. S. Geol. Surv., pp. 199–322, with plates). Alden’s work above referred to maps a part of the region. Grant and Burchard have studied the geology of the Lancaster and Mineral Point Quadrangles (Folio U. S. Geol. Surv. 145). Their text-figure 1 is here reproduced, inasmuch as it shows the relation of the region to the surrounding glaciated areas (fig. 14). The topographical map of Folio 145 and that of Chamberlin and Salisbury will show the uneven character of the surface. This has resulted from the erosion undergone during the whole of the Pleistocene. Much of the area is covered with a coating of loess. Along Mississippi River this may be as much as 10 feet thick, but at a distance of from 30 to 40 miles it becomes reduced to a few inches. Considering this erosion, one might conclude that few vertebrate remains would be preserved; nevertheless they are not wholly missing.

In 1862 (Geol. Surv. Wisconsin, vol. I, p. 136), J. D. Whitney stated that he had found in a crevice at Blue Mounds, Wisconsin, remains of the mastodon (p. 111), a peccary (p. 219), bones and teeth of a buffalo (p. 270), and a wolf which he referred with doubt to _Canis latrans_. The depth was uncertain, but it may have been as much as 40 feet. The fossils were embedded in reddish clayey loam, the usual crevice earth. On page 422 of the same volume, Jeffries Wyman referred the wolf remains to two distinct species, _Canis occidentalis_ and _C. latrans_. In 1876, Dr. J. A. Allen (Amer. Jour. Sci., ser. 3, vol. XI, pp. 47–49) described from the same lot of bones the species _C. mississippiensis_. This apparently did not include jaws and teeth that Wyman had referred to _C. occidentalis_. In Wyman’s paper, on page 422, he assigned three teeth to _Dicotyles torquatus_, an existing peccary, without stating that it had been found at Blue Mounds. In 1869 (Jour. Acad. Nat. Sci. Phila., ser. 2, vol. VII, p. 384), Leidy referred this peccary to his _Dicotyles lenis_, an extinct species. Inasmuch as the peccaries found at Galena were identified by Leidy (Whitney, vol. cit., p. 424) as _Platygonus compressus_ (p. 218), it appears pretty certain the _Dicotyles lenis_ (_Tagassu lenis_) was among the fossils collected at Blue Mounds (p. 219). It must, however, be kept in mind that Whitney, on page 35, stated that he had collected bones and teeth of the same animal near Dubuque, Iowa. Allen regarded the buffalo as belonging to an extinct species; but it is really undeterminable. Accordingly there may be credited to this locality the following species: _Tagassu lenis_, _Bison_ sp. indet., _Mammut americanum_, _Canis nubilus_ (_C. occidentalis_), _C. mississippiensis_, _C. latrans_.

FIG. 14.—Relation of driftless region of Wisconsin, Iowa, and Illinois
to glaciated areas. From Grant and Burchard. Unshaded area
represents driftless region.
]

In Whitney’s report, on page 133, he announced the finding of a large quantity of bones of mastodons at Sinsinawa Mound (p. 111), but he did not know at what depth they occurred. It seems probable that they had been met with in one or more crevices.

It seems probable that the animals found in crevices in the lead region of Wisconsin, Illinois, and Iowa belong approximately to one geological stage of the Pleistocene. The following appears to include all known to have occurred in such situations:

Megalonyx jeffersonii?. Platygonus compressus. Tagassu lenis. Odocoileus virginianus?. Cervus canadensis. C. whitneyi. Antilocapra americana. Bison sp. indet. Mammut americanum. Marmota monax. Microtus sp. indet. Geomys bursarius. Sylvilagus floridanus? (Lepus sylvaticus). Anomodon snyderi. Procyon priscus. Canis nubilus (C. occidentalis). C. mississippiensis. C. latrans.

The writer was at one time inclined to believe that these animals belonged to the time succeeding the withdrawal of the Wisconsin ice-sheet. Baker (“Life of the Pleistocene,” p. 353) thinks that they belong probably to the Peorian, inasmuch as the region is covered by Iowan loess, beneath which many of the bones have been found. It is quite probable that those crevices were open during at least some part of the Pleistocene and that animal remains collected in them. The fossils are reported as being sometimes inclosed in a matrix of cave or fissure materials which are cemented together by iron. The considerable number of extinct species, certainly 7 out of about 18, makes it probable that the fauna is not so recent as the Late Wisconsin.

It appears to be determined that the Iowan loess was formed immediately after the retirement of the Iowan ice-sheet. It might, therefore, be a question whether all of these animals might have got into those crevices in time to be covered in by the loess. On the other hand, the Illinoian drift was, for a long time, exposed to weathering and erosion before the Iowan drift and loess were laid down. Also, the Sangamon interval was probably much longer than the Peorian, so that the chances for the accumulation of the fossils were greater. It seems, however, that we can only say that the fossils are post-Illinoian and probably pre-Wisconsin.

Besides the vertebrate fossils referred to above, a few others, especially mastodons (pp. 110, 111), have been found at other places, but so little is known of the conditions of their interment that they furnish little geological information.

A very interesting region is found in the western part of the State, in Dunn and Pepin Counties. This has been examined with great care by Dr. Samuel Weidman, State geologist of Wisconsin. About Menomonie there are several brickyards, whose excavations furnish opportunities for studying the formations at that point. Sections of one of these brickyards are described and illustrated by Dr. E. R. Buckley, in Bulletin VII, part 1 (1901), page 194, plate XXXVII. A section and brief description is found also in a paper by Dr. Hussakof (Jour. Geol., vol. XXIV, p. 688). In that region are found outwash gravels which have been definitely correlated by Weidman with Iowan drift. In some places this is overlain by loess. These gravels vary from 10 to 20 feet in thickness at Menomonie. Beneath the gravels are found lacustrine clays varying in thickness from 20 to 40 and even 60 feet. These are stratified and consist of layers from 1 to 12 inches in thickness, with intervening thin layers of sand. Toward the bottom the sand increases in amount. Beneath the clay-bearing formation is a bed of sand attaining a maximum thickness of about 150 feet. This is underlain by coarse sand and gravel. The lacustrine clays and the underlying sands and gravels are included by Weidman in his Menomonie formation, and this is believed by him to be of Sangamon interglacial age. In northwestern Wisconsin are found other glacial deposits believed to belong to the Illinoian drift epoch.

In the lacustrine clay at Menomonie have been found remains of the great lake trout, _Cristivomer namaycush_ (Hussakof, as cited above), of a deer (p. 230), a caribou (p. 247), and probably a mastodon. The deer is represented by a single vertebra, identified by Dr. W. D. Matthew. The supposed mastodon is indicated by the distal end of the right femur, the caribou by an antler of a young and probably female individual and by the shaft of a large individual.

At Woodville, in St. Croix County, about 20 miles west of Menomonie, has been found a forest bed regarded as belonging to the Aftonian. This was described by Arthur Koehler (Amer. Forestry, vol. XXVI, Feb. 1916, p. 92, 3 figs.). Wood was found that was identified as that of spruce.

In 1913 (Science, n. s., vol. XXXVII, p. 457), in a brief abstract, Weidman reported that in Wisconsin he recognized drift deposits of Wisconsin, Iowan, and Kansan ages and another still older. No localities were mentioned, but his statements were doubtless based mostly on his work in the western part of the State. The loess was found to be laid down after the Iowan and before the Wisconsin. Interglacial deposits were found between the Kansan and the Iowan.

In 1905 (Jour. Geol., vol. VIII, pp. 238–256) and in 1910 (Jour. Geol. vol. XVIII, pp. 542–548), Dr. R. L. Chamberlain presented the results of his investigations on the “Pleistocene Geology of the St. Croix Region in Western Wisconsin.” His conclusion (p. 548) was that in that part of the State there were present (1) a surface mantle of gray Wisconsin drift deposited by a glacier from the Keewatin center; (2) red Wisconsin drift deposited by a glacier coming from the Labrador center; (3) a red drift left by an ice invasion from the Labrador center, its age consistent with Illinoian; (4) a grayish-black till that had come from the Keewatin center and whose age was probably Kansan.

MARYLAND AND DISTRICT OF COLUMBIA.

For obvious reasons the Pleistocene geology of the District of Columbia is considered in connection with that of Maryland. This region is of especial interest, because of the long time and the care which has been bestowed on it by geologists and because the conclusions reached have been applied to the geological study of States both toward the north and toward the south.

The most complete exposition of the Pleistocene geology of the region is to be found in the volume of the Maryland Geological Survey entitled “Pliocene and Pleistocene,” published in 1906. The geological treatise itself was written by George Burbank Shattuck and is illustrated by many maps and text-figures. Included in this is a bibliography of the subject which occupies 17 pages. There is a chapter by W. B. Clark, Arthur Hollick, and F. A. Lucas, on the interpretation of the palæontological criteria; another by F. A. Lucas on the mastodons and the elephants. The Pleistocene mollusks found in the State, 40 species, were described and figured by W. B. Clark; while the plants, also nearly 40 in number, were described and figured by Arthur Hollick.

The history of the development of our present knowledge of the geology of Maryland and the classification of its formations up to 1906 is given by Shattuck in the volume just cited (pp. 25–40). This geologist recognized in the superficial deposits of the State five formations (fig. 15). These are, beginning with the oldest, Lafayette, Sunderland, Wicomico, Talbot, and Recent.

FIG. 15.—Diagram showing the ideal arrangement of the supposed
terraces in the Maryland Coastal Plain. From Shattuck.
]

The Lafayette is regarded as having been laid down during the Pliocene. The Sunderland, Wicomico, and Talbot form three terraces, of which the Sunderland is the oldest, most elevated, and farthest away from the larger bodies of water. It is composed of clay, peat, gravel, and boulders supposed to have been brought in by the ice. The coarser materials appear to occupy usually the lower parts of the formation. The elevation near Washington is about 200 feet, but southward it descends gently, until in St. Mary’s County it is only about 60 feet. The thickness varies from about 80 feet to nothing. According to Shattuck, at the time of deposition of the Sunderland the coast was depressed to an extent of about 200 feet, so that its materials were laid down either in salt water or in that of wide estuaries. No deposits belonging to it have been found in the eastern peninsula. In the western peninsula considerable areas are recognized along the Potomac up to Washington and along the Patuxent and Chesapeake Bay to Baltimore and Elkton. Except in the southern part of this peninsula, the Sunderland is found only in widely separated patches. No marine organisms are known to have left their remains in the Sunderland, but forest trees of a number of existing genera and several extinct species have been described by Hollick in the volume cited.

The Wicomico formation is described as occupying a large portion of the central and higher parts of the eastern peninsula; in the western it forms a narrow and often interrupted fringe around the Sunderland. North of Washington and Annapolis it occurs only in patches. Its materials are very similar to those of the Sunderland. Its greatest elevation is about 100 feet above sea-level, and this, according to Shattuck’s view, marks the amount of depression of the land at that time. The thickness may be as much as 70 feet, but is usually much less. No marine fossils proper to the period have been discovered in the deposits, but at a point in Prince George’s County plant remains have been found in a deposit about 20 feet thick.

The Talbot formation forms a fringe, sometimes of great width, sometimes narrow or interrupted, along all the large bodies of water in this State and in Delaware. It is the lowest of the terraces. The greatest elevation is about 45 feet; the thickness does not exceed 40 feet. The materials noted are those of the other two formations—clay, peat, sand, gravel, and ice-borne boulders. At several points along Chesapeake Bay and on the lower part of Patuxent and Potomac rivers, deposits containing plant remains have been discovered, including pines, cypress, hickory, beech, elm, and black locust. In contrast with the other formations, the Talbot has furnished many marine fossils, mostly mollusks; but in all cases the localities are close to the present coast.

The writer does not accept the theory that the materials forming what have been called the Sunderland, Wicomico, and Talbot terraces have been to any great extent laid down in the sea. Some part of the Talbot, that lying near the present coast, has undoubtedly had such an origin. Nor has the Coastal Plain suffered, so far as is determinable, any such amount of depression as the theory mentioned requires. The materials of the Sunderland and Wicomico have, in the writer’s opinion, been brought down by rivers whose beds lay at levels nearly as high as those of the real or supposed terraces. When the Talbot materials were laid down, the rivers and estuaries of the coast had been cut down nearly to their present levels, and this was not long after the beginning of the Pleistocene.

The authors of the submergence theory admit that no satisfactory evidence of the presence of marine organisms, vertebrate or invertebrate, are to be found in the body of the assumed terraces, except again in parts of the Talbot which immediately border the ocean or the great estuaries. It is almost inconceivable that the ocean could occupy the Coastal Plain from New Jersey to Mexico for thousands of years and lay down great thicknesses of clay, sand, and gravel without having left somewhere beds of molluscan shells in such situations that they would have been discovered. While these marine fossils are lacking, there are found on all these terraces from Maryland to Florida and to the Rio Grande an abundance of land vertebrates such as elephants, mastodons, horses, camels, peccaries, and many other forms. Nor do our palæobotanists have difficulty in finding oaks, walnuts, hickories, poplars, etc. On the theory of submergence there are missing all the things that ought to be found and there are met with just the things that would not be expected.

A figure is here reproduced (fig. 15) from the Maryland Pliocene and Pleistocene volume, page 66, with the explanation there accompanying it. The reader may judge for himself whether the sea could occupy the Atlantic coast since Pliocene times without leaving any traces of marine fossils, while at the same time there were preserved in those terraces remains of land animals and land vegetation.

Another section (fig. 16) is reproduced from Folio 179 of the U. S. Geological Survey, the authors of which are G. W. Stose and C. K. Swartz. The uppermost terraces are by these authors supposed to belong to the late Pliocene, the formation formerly known as the Lafayette. These figures suggest that the one set of terraces have some connections with the other set.

FIG. 16.—Section across Potomac River near Big Pool, Maryland. Shows
gravel-covered terraces. Folio 179, U. S. Geol. Survey.
]

Beginning at the southern extremity of Maryland, we notice the occurrence of remains of _Mammut americanum_ at or near St. Mary’s City. Other remains of the same animal have been secured near St. Clements in St. Mary’s County (p. 112). Both of the localities are situated on territory mapped by Shattuck as Wicomico; but as remarked on page 112, our knowledge of the conditions under which the fossils were found is not sufficient to allow us to say more than that they belong to the Pleistocene. The species existed from early to late Pleistocene and can not be used to determine the age of the deposits.

Along Patuxent River, in Charles County, not far from Benedict, Cope (Proc. Acad. Nat. Sci. Phila., 1867, p. 155) recognized jaws and teeth of _Grison macrodon_ and of _Tagassu lenis_ (p. 220). Both are extinct species.

According to Shattuck’s map of 1906, this region is covered by the Talbot formation; but inasmuch as the species named were obtained from pits furnishing Miocene marl, one can not be sure that they are not older than the supposed Talbot. It would probably require a search in the land records in order to determine exactly where the objects were found. The presence of _Elephas primigenius_ suggests that this animal had been pushed down here during one of the glacial stages.

Nearly a hundred years ago an elephant tooth (p. 154) was found somewhere in Queen Anne County, but it would probably be now impossible to determine the locality. In case the elephant tooth was found near Chesapeake Bay, as is very probable, there is no record of any Pleistocene vertebrate having been found in the central and eastern parts of the eastern peninsula.

In the eastern peninsula remains of Pleistocene vertebrates have been recorded from only two localities, Oxford Neck, Talbot County, and an undetermined locality in Queen Anne County. From Oxford Neck, Cope (Proc. Amer. Philos. Soc., vol. XI, 1869, p. 178) reported _Elephas primigenius_, _E. columbi_, _Cervus canadensis_, _Odocoileus virginianus_, _Chelydra serpentina_, and _Terrapene eurypygia_.

At Chesapeake Beach, William Palmer, of the U. S. National Museum, discovered a few remains of Pleistocene vertebrates. One of these is a tooth of an undetermined species of _Bison_, probably not the existing one. Another species is probably _Equus leidyi_ (p. 189). Three teeth appear to represent the peccary _Tagassu lenis_ (p. 220). In 1921, Dr. Adolph H. Schultz, of the Johns Hopkins Medical School, presented to the U. S. National Museum another specimen of _T. lenis_ which he had found at Chesapeake Beach. Inasmuch as the fossils were picked up after having fallen from their resting-place, it is impossible to say to which formation they belonged. In the opinion of the writer, none of the three species indicates a late Pleistocene time.

On the opposite side of the western peninsula, at Marshall Hall, Charles County, there was found long ago a tooth which the writer refers to _Equus leidyi_.

Coming north into the District of Columbia, we find recorded the discovery of remains of horses and possibly at two different times. According to Darton’s work (Folio 70, U. S. Geol. Surv.), there is some later Columbia laid down along the route of the Chesapeake and Potomac Canal above Georgetown. This would now doubtless be regarded as belonging to the Talbot. It seems to follow that either the Talbot is much older than has been supposed or that some of the extinct horses continued on until a comparatively late time in the Pleistocene.

Within the limits of the city of Washington there has been found a tooth of probably _Elephas primigenius_ at a depth of 35 feet, in the Wicomico formation (see p. 178). On any theory of the origin of the terraces, the presence of the tooth at that depth in the ground and at that elevation appears to indicate a considerable geological age for the animal. To what extent materials may have been washed down from the surrounding higher land may be difficult to determine.

In Prince George County, near Mitchellville, have been found two teeth of an extinct horse (p. 188). These are as yet unidentified. They are in the U. S. National Museum, No. 8813.

Near Towson, in Baltimore County, a mastodon tooth has been found (p. 112); but beyond proving that there is at that locality some Pleistocene deposit, it gives us little information.

In 1920 (Proc. U. S. Nat. Mus., vol. LVIII, pp. 96–109), the writer described a collection of vertebrate fossils, collected in a cave or fissure in limestone at Cavetown, Washington County, by anthropologists from Phillips Academy, Andover, Massachusetts. The following is the list of species that were found in the collection:

Crotalus horridus. *Equus complicatus (p. 189). *Equus giganteus? (p. 189). *Mylohyus nasutus (p. 220). *M. exortivus (p. 220). *M. obtusidens, n. sp. (p. 220). *Platygonus tetragonus? (p. 220). *P. vetus? (p. 220). *P. cumberlandensis (p. 220). *Sangamona fugitiva. Odocoileus virginianus (p. 231). *Elephas columbi? *Sciurus tenuidens, n. sp. S. hudsonicus. S. carolinensis. Marmota monax. Castor canadensis. Ondatra zibethica. Neotoma magister. Microtus pennsylvanicus. Erethizon dorsatum. Sylvilagus floridanus. Ursus americanus. *Smilodontopsis mooreheadi. Felis couguar.

Of the 22 species here recognized 12 are extinct. This large number of itself indicates that their time of existence was not recent. Similarly, the presence of 2 species of horses, several species of peccaries, and of a saber-tooth tiger points to a rather ancient period. The writer believes that the assemblage belongs to the Sangamon stage of the Pleistocene.

FIG. 17.—Generalized section across the Allegheny Valley at Parkers
Landing, West Virginia, showing various stages of erosion and valley
fill. U. S. Geol. Surv. Folio 178.
]

In Washington County, probably along Lane’s Creek, was found, in digging a mill-race, the skull of a mastodon (p. 112). Further east, near Clear Spring, and about a mile above the entrance of Conococheague Creek into the Potomac, was discovered a tooth of a mastodon (p. 113). This had been washed out of some deposit along this creek, probably not far away from where it was found. As Stose has shown (Hancock Folio, No. 179, U. S. Geol. Surv.), along the Potomac and its tributary streams there are extensive Pleistocene deposits of sand and gravel, laid down when the river was as much as 200 feet above its present level. It is probable that such deposits date from the early Pleistocene (fig. 17). A more important locality for Pleistocene vertebrates is that near Corriganville, about 3 miles west of north of Cumberland, Maryland. The cave is in Allegany County, west of Wills Creek and south of Jennings Run, about 0.5 mile south of the village of Corriganville. An account of this locality, with a list of the species determined up to that time, has been published by Gidley (Proc. U. S. Nat. Mus., vol. XLVI, 1913, pp. 93–102). In cutting through a spur of limestone in making a railroad, at a depth of about 100 feet there was exposed a cave or fissure which contained many bones and teeth. Gidley secured some hundreds of specimens belonging to about 35 species. Unfortunately nothing has been published which shows the relation of this cave to the terraces which are found along Potomac River and its tributaries. Through the kind offices of Mr. F. S. Rowe, welfare agent of the Western Maryland Railway, the writer has received from the division engineer, Mr. P. Cain, of Cumberland, a topographic map of Allegany County and a profile of the road extending through the rock cut. From these it appears that the level of the track, at the fissure, is 837 feet above sea-level. This seems, therefore, to be considerably above the highest terrace along the Potomac in that region. It is to be supposed that the fissure was formed long before the animal remains accumulated in it.

In a paper published in 1920 (Proc. U. S. Nat. Mus., vol. LVII, pp. 651–678, plates LIV, LV, text-figs. 1–10) Gidley added to his former list four species of peccaries, as follows: _Platygonus cumberlandensis_, _P. intermedius_, _Mylohyus exortivus_ (all new), and _M. pennsylvanicus_. In another communication he reported also a deer, a wolverine, a beaver, a lynx, a badger, a marten, an eland, and a crocodile or an alligator (Rep. Smithson. Inst. for 1918, pp. 281–287). Many of the identifications are merely provisional.

_Provisional list of fossils found near Corriganville._

1. Alligator or Crocodylus sp. indet.

2. Blarina brevicauda?.

3. Vespertilio grandis.

4. Vespertilio sp. indet.

5. Myotis sp. indet.

6. Ursus vitabilis.

7. Ursus americanus?.

8. Canis armbrusteri.

9. Canis sp. indet.

10. Vulpes? sp. indet.

11. Mustela vison?.

12. Gulo luscus?.

13. Taxidea sp. indet.

14. Lynx sp. indet.

15. Mammut americanum.

16. Equus sp. indet. (p. 189).

17. Tapirus haysii? (p. 204).

18. Platygonus cumberlandensis (p. 220)

19. P. intermedius (p. 220).

20. P. vetus? (p. 220).

21. Mylohyus exortivus (p. 220).

22. M. pennsylvanicus (p. 220).

23. Odocoileus sp. indet.

24. Taurotragus americanus.

25. Ochotona princeps?.

26. Lepus americanus?.

27. Lepus sp. indet.

28. Sciurus hudsonicus.

29. Sciuropterus alpinus?.

30. Marmota monax?.

31. Castor sp. indet.

32. Neotoma sp. indet.

33. Microtus chrotorrhinus?.

34. Synaptomys borealis?.

35. Synaptomys sp. indet.

36. Peromyscus leucopus?.

37. Napæozapus sp. indet.

38. Erethizon sp. nov.

On account of the present unstudied condition of the collection, it is difficult to reach conclusions that are satisfactory. It appears, however, that there are at least 6 hitherto undescribed species, one-fifth of the whole number. Another 6, if at all correctly determined, indicate a wide removal from their ranges of the present day. _Lepus americanus_ now lives well toward the north, coming down to Saginaw, Michigan. _Ochotona princeps_ lives in the Rocky Mountains of British America. _Synaptomys borealis_ is known only from the region about Great Bear Lake, Mackenzie, Canada. _Microtus chrotorrhinus_ has its habitat in Quebec and the northeastern United States. The species of _Napæozapus_ are Canadian in their range, but descend to southeastern Maryland and to North Carolina in the mountains. _Sciuropterus alpinus_ is found from Alaska to Hudson Bay, but descends on the Pacific coast to southern California. This northern habitat of so many supposed species suggests that the fissure received its contents during one of the glacial stages, and this may be the case. However, it is not unlikely that these species and some others are really undescribed ones. One may reasonably expect to find in a fauna containing _Equus_ and _Tapirus_ a much higher percentage of extinct species than Gidley has recorded.

The most remarkable member of the fauna is _Taurotragus americanus_, a species closely related to the eland of southern Africa (Gidley, Smiths. Misc. Coll., vol. LX, No. 27). Its presence in western Maryland gives a vivid impression of the widely extended journey that some animals have made from one continent to others. The same species has since been found in collections made at Alton, Illinois (p. 339), and at Kimmswick, Missouri (Proc. U. S. Nat. Mus., vol. LVIII, p. 113).

According to the author’s views, the fauna found at Cumberland, like that of localities in western Virginia, belongs to a time somewhere about the middle of the Pleistocene. Most of the species may be supposed to have lived there during the warm Sangamon stage; others, as the wolverine, at a somewhat earlier or later time when the climate was cooler.

VIRGINIA.

For the student of Pleistocene vertebrate palæontology, as for the geologist, Virginia may be divided into three physiographic regions, the Coastal Plain, the Piedmont Plateau, and the Appalachian Mountains. The line which divides the Coastal Plain from the Piedmont Plateau begins at the southern boundary of the State, at about 77° 31′ longitude. The towns on or not far from this nearly north-and-south line are Emporia, Petersburg, Richmond, Hanover, and Fredericksburg. Near the latter the line inclines slightly eastward and passes a few miles west of Alexandria and Washington, D. C. The Coastal Plain is much less elevated than the region west of it and consists of deposits of Mesozoic or Cenozoic age, and much of it is covered by Pleistocene materials. The Plateau region is elevated and consists mostly of Palæozoic rocks, mostly metamorphosed into a crystalline condition. The Appalachian region presents nearly parallel ranges of mountains and intervening valleys.

For a knowledge of the Pleistocene geology of the Coastal Plain the reader should consult Bulletin iv, 1912, of the Virginia Geological Survey. The authors who discuss the physiography and geology of this region are William B. Clark and Benjamin L. Miller. On pages 19 to 45 they present a very full bibliography of the geological literature pertaining to this region. Additional valuable assistance may be obtained from the various folios issued by the United States Geological Survey, but unfortunately not many species of vertebrate animals have been found on this Coastal Plain of Virginia.

In Bulletin IV, already mentioned, Clark and Miller recognize the presence of three terraces belonging to the Pleistocene. To these are given the names applied in Maryland and North Carolina to what are regarded as equivalent terraces. The oldest of these, most elevated and farthest from the coast, is the Sunderland; eastward of this lies the Wicomico; the Talbot is the youngest and lowest and borders the coast. Unfortunately, the geologists referred to did not map the areas occupied individually or collectively by these terraces. They accept the theory that these terraces were laid down in the sea. It is admitted, nevertheless, that no marine fossils are found in deposits of the Sunderland and Wicomico. In the Talbot, 26 species of marine mollusks have been reported from Talbot deposits of the Dismal Swamp Canal, all regarded as belonging to living species. It will be recollected that Woolman (Proc. Acad. Nat. Sci. Phila., 1898, p. 414), in a study of mollusks collected in the Dismal Swamp Canal, found 7 extinct species in a collection of 49 species, equal to about 16 per cent. It is, however, not unlikely that the collections had been dredged up from deeper deposits.

In Bulletin V of the Virginia Geological Survey, on page 25, Sanford stated that the Talbot had a width of 30 miles at the south. On consulting Stephenson’s map of the superficial formations of the Coastal Plain in North Carolina (North Carolina Geol. Surv., vol. III, plate XIII) it will be seen that this corresponds quite exactly with the width of the Pamlico formation at that line. For the writer’s views on the terraces named the reader may consult page 346 on the geology of Maryland.

On page 113 is recorded the discovery of a tooth of a mastodon in a marsh near Disputanta, in Prince George’s County. Not enough is known about the geology of the region to say more than that the deposit belongs to the Pleistocene.

About 6 miles east of Williamsburg, a little more than 100 years ago, remains which pretty certainly belonged to the genus _Mammut_ and probably to the species _M. americanum_ (p. 113) were discovered, said to have been found on the banks of York River; but by this was probably meant the banks of the flood-plain. The bones were found in marsh mud and were surrounded by roots of cypress trees. The adjacent bank was 20 feet higher than this level. The topographical map of the Williamsburg Quadrangle shows that an abrupt rise of this amount is to be found only about 10 miles away from the river. Whether the cypress roots were those of trees that had grown within recent years or whether they were remains of a Pleistocene forest, such as was exposed at Tappahannock, Essex County (Bull. IV, p. 186), the writer does not know. The information at hand about this case does not make it possible to pronounce on the geological age of the mastodon.

On page 28 an account is given of the discovery of a skull of a walrus on the Atlantic coast of Virginia, at Accomac. It had doubtless been washed up by the sea from a Pleistocene deposit. It is easiest to suppose that the walrus had been driven southward along the coast during the Wisconsin glacial stage; but possibly this happened during an earlier glacial time.

No vertebrate fossils of Pleistocene age appear to have come to light anywhere on the Piedmont Plateau, and little or nothing is known about its Pleistocene geology.

From the geological surveys we get little information about the Pleistocene formations of the Appalachian region. At most, mention is made of soils of undetermined age along the streams; and yet from this region have been obtained a very considerable number of Pleistocene vertebrates.

From Mr. Wyndham Robinson, of Abingdon, Washington County, the U. S. National Museum received in 1869 a tooth of _Mammut americanum_ (p. 113) and one of _Equus complicatus_ (p. 189). Nothing has been learned regarding the conditions under which they were unearthed. The horse-tooth points to an age preceding the Wisconsin drift.

From Saltville, in Smyth County, the following forms have been obtained:

Crocodylus sp. indet. Megalonyx dissimilis (p. 34). Equus sp. indet. (p. 190). Odocoileus? sp. indet. (p. 231). Cervalces sp. indet. Bison sp. indet. (p. 259). Mammut americanum (p. 113). Elephas primigenius (p. 145).

That a crocodile should have lived in this region during the Pleistocene is remarkable. _Megalonyx dissimilis_ is otherwise known only from Natchez, Mississippi, from deposits which appear to be of about Illinoian or Sangamon age. The horse-tooth points to about this time or earlier, while the other species do not contradict this conclusion. The astragalus referred to _Odocoileus_ probably belongs to some other genus.

Mr. M. D. Mount sent to the U. S. National Museum remains of _Bison_ (p. 259), _Mammut americanum_ (p. 113), and _Elephas primigenius_ (p. 145). These, he reported, had been found at a depth not greater than 8 feet in excavating for the city reservoir. He has written that the valley of Holston River at Saltville, within about 80 years, had been a lake, at least at certain times of the year, and that the reservoir was excavated at the margin of this low area.

Mr. O. A. Peterson (Ann. Carnegie Mus., vol. XI, 1917, pp. 469–474) reported from this place the crocodile, the megalonyx, cervalces, the supposed deer, the horse-tooth, and remains of mastodons. The bones were found in a sink-hole, in a layer of coarse gravel, pebbles and cobblestones, a fact indicating that a stream of some size had occupied the place. Overlying this layer was one in which there were fragments of large river shells. The bone layer appears to have been only about 4 feet from the surface. Peterson concluded that at the close of the Pleistocene or later the remains had been moved and redeposited from some place not far away, but this would not affect the geological age of the fossils and it is evident that remains of vertebrates are widely dispersed in that valley. All the species reported are extinct, but only large forms were secured.

Professor Cope, probably in 1868, found the following 24 species. He did not state the localities exactly, except that they were along New River, in Wythe County. Two were on the land of Abraham Painter. The writer applied to the surveyor of the county named and has been informed that the farm which belonged to Abraham Painter is on New River, near the town of Ivanhoe. The nomenclature of the species has been revised. The species preceded by a dagger are extinct.

†Megalonyx jeffersonii (p. 34). Castor fiber. Neotoma floridana? Marmota monax. Peromyscus leucopus. †Tamias lævidens. †Sciurus panolius. Sylvilagus floridanus. Blarina sp. indet. Vespertilio sp. indet. †Tapirus haysii (p. 204). †Equus complicatus? (p. 190). †Mylohyus nasutus (p. 221). Odocoileus virginianus (p. 231). †Bison sp. indet. (p. 260). †Ursus amplidens. Procyon lotor. Spilogale putorius. †Myxophagus spelæus. Crotalus sp. indet. Amyda sp. indet. Terrapene sp. indet. Cryptobranchus sp. indet.

At least 9 of the 24 species are extinct. None of the recorded species requires us to refer the deposit to early Pleistocene times. _Ursus amplidens_ was described from the deposits at Natchez. This and _Tapirus haysii_, _Equus complicatus_, and _Mylohyus nasutus_ point to middle Pleistocene, apparently about to Illinoian or Sangamon times.

Cope reported that the teeth and bones were found in a cave breccia. This consisted of a number of irregular masses which occupied “depressions and short galleries” in the southeast side of a line of hills. When those masses were excavated from their beds the floor and roof of a portion of a cave were exposed, with the stalactites, stalagmites, and usual incrustations. It would appear, therefore, that at some time in the early Pleistocene or in the late Pliocene the caves had been formed through the effect of streams of carbonated waters on the limestone; that in some way the bones and teeth of the animals listed above had got into the cave; that by a change in the amount or character of the water the caves had gradually filled up; and that afterwards the limestone which contained these caves had undergone great erosion.

Further north, in the valley of Jackson River at Covington, there is evidently a deposit of Pleistocene clay, for in it at a depth of 12 feet was found a tooth of a mastodon (p. 114). Another mastodon tooth was found near Hot Springs, at the head of Wilson Creek, in Bath County, possibly in similar deposits (p. 114). In Augusta County an unidentified species of horse (p. 190) and the peccary _Platygonus_ (p. 221) have been discovered.

WEST VIRGINIA.

So far as the writer has learned, vertebrate remains belonging to the Pleistocene have been found in West Virginia in only eight places and only seven species are represented: _Mammut americanum_ (p. 115), _Elephas_ sp. indet. (p. 179), _Equus niobrarensis?_ (p. 190), _Symbos cavifrons_ (p. 254), _Megalonyx jeffersonii_ (p. 34), _Odocoileus virginianus?_ (p. 231), and a peccary (p. 221). The horse appears to indicate an early Pleistocene time, possibly pre-Kansan, but all the other species continued from at least the Aftonian stage through to the Late Wisconsin. The specimens, therefore, do not help us to determine the age of the deposits in which they are found.

No part of the State lies within the glaciated area; hence, during the whole of the Pleistocene epoch its surface was subjected to weathering and to the erosion of running water. At times the streams built up deposits on their beds. Later they deepened their channels and left a part of their former deposits as terraces. At a still later time the deposition and deepening may have been repeated, and as a result there is sometimes a series of terraces one above another. The age of these terraces and their origin have been the subjects of a good deal of controversy.

In the Masontown-Uniontown Folio (U. S. Geol. Surv. No. 82), M. R. Campbell has discussed the terraces along the Monongahela River, which occur at an altitude of about 1,000 feet above sea-level and perhaps 150 feet above the present river. Also more than 100 feet above the present river are old abandoned river channels which are now partially filled up.

In 1911 (U. S. Geol. Surv. Folio 178, pp. 11–13), E. W. Shaw and M. J. Munn described the Quaternary of the Foxburg and Clarion quadrangles in Pennsylvania, where the same Pleistocene problems are involved. They present an account of the different views regarding the high-level terraces and the abandoned channels. They concluded, as did Campbell, that these terraces and channels dated back to the early Pleistocene and probably to the Kansan stage. Figure 17 is a reproduction of Shaw and Munn’s figure 10, on their page 12. It represents a section across Allegheny River at Parker’s Landing, Armstrong County, Pennsylvania. The uppermost gravels in the figure would be those of supposed Kansan age; while the lowermost are those laid down during the last glacial stage, the Wisconsin. In the materials of the high terraces one may expect to find fossil vertebrates of the early Pleistocene, as in the case of the mastodon reported from Stewartstown, West Virginia (p. 116). The conditions of burial should, however, be carefully studied and recorded; for it would be possible for remains to be left at a later time on such a terrace and to be covered up by earth washed down from above.