C. L. COOPER
The Pleistocene is known as the great period of glaciation in North America. In fact there are five recognized advances with their corresponding retreats of the ice. This great ice sheet radiated from three centers or areas, from which each divisional sheet receives its name. The Labradorean is named from the area east of Hudson Bay. Ice from this sheet radiated to cover the eastern part of the United States and undoubtedly entered Kentucky. The Keewatin sheet emanating from the area just northwest of Hudson Bay covered central United States; and the Cordilleran sheet, located in the western part of the Dominion of Canada, failed to spread out nearly as much as the other two. The five glacial stages, beginning with the oldest are as follows: the Nebraskan, Kansan, Illinoian, Iowan, and Wisconsin. The intervening interval or period which existed between the retreat of one ice sheet and the advance of the next, were of unequal duration. It was during these interglacial epochs that the deposits containing the Pleistocene fossils accumulated. However, most of these deposits in Kentucky are not strictly glacial deposits, but are fluvio-glacial beds formed by the streams flowing from the edges of the melting ice. The first of these interglacial intervals, known as the Aftonian, occurred between the Nebraskan and Kansan invasions. The others in order were the Yarmouth, the Sangamon, and the Peorian. The last is thought to have occupied an interval about equal to the time that has elapsed since the retreat of the last ice sheet, the Wisconsin. The first three intervals probably were of much longer duration.
Fig. 33. Map of Kentucky showing Pleistocene glaciation.
It is certain that the Illinoian sheet entered Kentucky in a small area in the northern part of the State in the counties bordering the Ohio River from Bracken to Jefferson. (see fig. 36). However, recent finds of pebbles and boulders from Canada and the St. Lawrence Valley brought in by an ice-sheet, floating ice, or an ice-dammed lake may have been deposited as debris from the Nebraskan sheet.1
During the time when the ice was most widespread the environments were very unfavorable for the development of life, in fact practically all life retreated before the advance of the ice-sheet, so that the sum total of life on the Continent was greatly reduced during those times. Such rigorous periods caused the complete extinction of certain species of plants and animals, and others developed very rapidly in order to maintain an existence in their rapidly changing habitat. Deposits of the Sangamon stage which immediately followed the retreat of the Illinoian sheet are known from Iowa to New York and as far north as Toronto.2 The climate varied from cool to warm, being moist for the most part, resulting in a fauna that was most extensive and varied of the interglacial stages. The species of plants and animals in existence at that time are shown in the table following:
Fauna of the Sangamon Interglacial Stage3
The most interesting and abundant fossil record from the Pleistocene is found among the vertebrates. Of the few now living species that were then in existence, practically all are to be found in the bone deposits of Kentucky, as are most of the 20 species of animals now extinct. The discovery of the remains of a polar bear in the Breck Smith Cave in the Bluegrass, shows that animals, now native to cold or arctic climates, migrated south with the advance of the ice. Great numbers of herbivorous animals grazed on the grasses and other plants which sprang up after the disappearance of the ice. This abundance of prey attracted many flesh-eating animals, all of which left a record in the form of their teeth, bones, and horns buried in swampy places near springs and salt licks. Our very abundant record of these various kinds of animals is found at such places, known today as Big Bone Lick Springs and other similar localities. The Indians first discovered the "big bones" which were to be found at these places, and in 1739 and 1751 explorers noted the bone deposits in their reports; one collected a mastodon's tooth from Big Bone Lick.
The collection of fossils listed below were collected at several localities and have been identified by Dr. F. C. Baker.
List of Pleistocene Fossils from Henderson County
DESCRIPTION OF LOCALITIES [above]
A-G: About 2 miles northwest of Smith Mills. The hill, in
which the road cut exposure shows nothing but loess, excepting as noted
below, rises from an elevation of 375 feet A. T. to 440 feet A. T. The lower
elevation is the elevation of the probably late Wisconsin terrace, but the
loess is probably older than this terrace. At an elevation of 400 feet A.
T., a clay band, 2 to 8 inches thick, runs horizontally for the length of
the exposure, about 100 feet. No difference in character between the loess
above and that below this band was noted. The collections were taken from
the following elevations:
OCCURRENCE OF VERTEBRATE FOSSILS IN KENTUCKY5
Of historical interest is the fact that President Thomas Jefferson first discovered and named Megalonyx jeffersoni, a ground sloth very abundant and of wide distribution during the Ice Age. The remains of this animal have been found at Big Bone Lick and near Henderson. Mylodon harlani, a smaller sloth, has been found at Big Bone Lick and at Blue Lick. A beaver as large as a black bear, Castoroides ohioensis, is known to have inhabited Kentucky streams, as its teeth and bones have been found in the eastern part of the State. Two odd-toed ungulates, the Perissodactyla, are represented by the remains of an ancient tapir and a prehistoric horse. The tapir, Tapirus sinensis, has been found at McConnell's Run in Scott County and at Yarnellton Station in Fayette County. These animals are now found in more southern latitudes, and differ little from their Pleistocene ancestors. The horse, Equus complicatus, found at Big Bone Lick, was very abundant during this time.
The even-toed ungulates, the Artiodactyla, are represented by a large variety of species from the fossil beds of Kentucky. The peccaries, or American swine have been found at Big Bone Lick and on Crooked Creek in Rockcastle County. Platygonus compressus, the species representing this class of vertebrates, is now extinct. The common Virginia deer (genus Odocoileus) was living at that time, as shown by abundant Kentucky records. The "elk," or more properly the wapiti, Cervus canadensis, related to the great stag of Europe, is present as fossils at Big Bone Lick and in Wayne County. The caribou, Rangifer tarandus, another animal from the Old World, was present in Kentucky during this period. The Indians probably used the fossil caribou horns for ceremonial purposes, as horns that appear to be the same are found in many old Indian graves. The fossils are found at Big Bone Lick. Pleistocene moose have also been found in Kentucky, and are probably the same as the living ,species, Alces americanus. Cervalces scotti a very unusual "stag-moose," is quite different from any living species of stag or moose. This form is also found at Big Bone Lick, as is the musk-ox, Bootherium bombifrons. This ox, now found only in the far north, apparently had wide distribution in the Pleistocene. The bison came to America from Europe, and two Pleistocene species are found at Big Bone Lick, Bison antiquus and B. latifrons. The latter was very much larger than the living species, B. bison, had horns with a spread of 6 to 8 feet, and is thought to be the parent form of this genus. The presence of fossils of animals now living together with those of the extinct forms at Big Bone Lick shows that this locality was used by salt-eating animals for hundreds of centuries. Only one form of the carnivorous animals is found in the State, in contrast to the great number of herbivorous genera and species. This is a bear, Ursus americanus, although a fox (Urocycon scotti) now found only in warmer climates, may have lived in Kentucky during the Pleistocene. This form was found in Breck Smith Cave near Lexington.
The most interesting group of Pleistocene animals inhabiting
Kentucky are the ancient elephants, which came to America over the old land
bridge between Siberia and Alaska. The best known form Elephas primigenius
roamed throughout the northern hemisphere. It was adapted to cold climates,
being protected by a heavy coat of long wooly hair. Big Bone Lick and Blue Lick
Spring have yielded perfect skeletons of this form. Elephas columbi, a
huge beast standing 11 feet high at the
shoulders, has been found at Big Bone Lick. The American mastodon, Mammut americanum, is one of the earliest of the ancient elephants, even antedating the early mammoths. In spite of this early ancestry, this form continued long enough to become contemporary with man in North America. Bones of this form have been found in abundance in Kentucky at Big Bone Lick, Blue Lick, in the Green River Valley and well within the Eastern coalfield.6
DESCRIPTION OF PLEISTOCENE VERTEBRATES FOUND IN KENTUCKY
UROCYCON CINEREOURGENTEUS SCOTTI
A skull of Scott's gray fox has been found in the Breck Smith cave, about 8 miles west of Lexington. Dr. Hays reports7 the find indicates that the climate of central Kentucky was much warmer than it is now.
Plate LXXVI, fig. 2.
The only carnivore found in the bone deposits of Kentucky is the black bear, Ursus americanus. This is the same species of bear now living and which is all but exclusively northern in distribution. The family is very distinct, and although they live principally upon vegetable food, they have the dentition of the carnivorous animals. The Pleistocene representatives in America include the true bears (Ursus) and a large short-faced bear Arctotherium bonoerense.
Plate LXXIV. fig. 3.
This giant beaver attained the size of the black bear, and lived in the late Pleistocene. It came to North America, either from the Old World or South America, and became widely distributed in the eastern and middle states.
Plate LXXII, fig. 3.
The ground sloth is common to Pleistocene deposits in North America. The skull resembles that of the tree sloths in that it is short and broad. The lower jaw is short and massive and the chin vertical. The fore limb is shorter and slenderer than the hind, but of nearly the same length. The feet were connected to the limbs so that the animal must have walked on the outside of the foot in much the same manner as the living ant-bear. The very large club-shaped heel-bone formed the back portion of the outer edge of the foot. The teeth are 54 in number, the foremost separated from the others and more or less tusk-like in form. The grinding teeth are without ridges and worn smooth, showing that the animal fed principally on leaves.
Zittel8 sums up the manner of life of this form as
"The hip-bones, hind legs, and tail are characterized by enormous strength. The entire structure of the extremities proves that the gigantic sloth could move over the ground but slowly and clumsily; on the other hand, the fore limbs served as grasping organs and were presumably employed to bend down and break off twigs and branches and even to uproot whole trees, while the weight of the body was supported upon the hind legs and tail."
Plate LXXII, fig. 2.
This form is essentially similar to Megalonyx, in fact there is no wide range of variation among the three families of ground-sloths which lived at this time. The main differences are found in size, form and number of teeth, the shape of the skull, and the number of digits.
Plate LXXVIII, fig. 2.
The predominating peccary of the Pleistocene in North America was the genus Platygonus, which was thought to have been more advanced than the existing forms. It failed to survive, however, in spite of the fact that it was better fitted to continue. It was much a larger animal, with longer and heavier legs. The genus first appeared in middle Pliocene.
Plate LXXIV, fig. 2.
The Roosevelt elk or wapiti is common to the northern part of North America and is plainly of Old World origin.
RANGIFER (CARIBOU) TARANDUS
Plate LXXV, fig. 2.
This form, the caribou, is also a northern form of Old World origin, and is still existant in North America.
Plate LXXVII, fig. 1.
The moose, Alces americanus, is essentially no different from the Old World species, and with the caribou and wapiti, are thought to have originated there.
Plate LXXV, fig. 1.
This form is different from any now living. It is closely related to the moose and the neck, body, limbs, and feet are almost identical. However the skull and antlers are very much different; the nasal bones are shorter than the moose, indicating a smaller snout. The antlers in general, are like those of the moose, but are less palmate and carry a trumpet-like plate on the lower side of each antler. This form is sometimes called the "stag-moose," and is thought to have migrated from eastern Asia, although no identical forms have been found in the Old World.
Plate LXXVI, fig. 1.
The Virginia deer is a southern form in contrast to the four previously described forms which are found in the northern part of the continent.
This form of the musk-ox ranged from Alaska to Arkansas and is one of three extinct genera found in the American Pleistocene. Symbos differs from the living form Ovibos in its smaller and shorter horns. The skull of Bootherium bombifrons, another Pleistocene musk-ox, is shown in Pl. LXXIV, fig. 1.
Plate LXXVII, fig. 3.
The remains of the musk-oxen have been found as far south as Oklahoma, but mostly along the terminal moraine formed by the front of the last ice invasion. This form, one of strictly arctic or cold region habitat, shows conclusively the character of the climate during the advance of the ice. The presence of bones of the extinct form, Symbos, and the two living forms, O. moschatatus and O. wardi, with those of the caribou in regions that are now warm or temperate is a good indication of the influence of the ice sheet upon climate.
This form was much larger than the living species, B. bison (See Pl. LXXVIII, fig. 1B) and is readily distinguished by the position of the horns at right angles to the axis of the skull. The remains of this species have been found only in California and Kentucky.
Plate LXXII, fig. 1; PI. LXXVIII, fig. 1A.
This early Bison was the giant of the race, and is thought to have far exceeded any of its living relatives in size. The largest skull found carries horns that measure 6 feet across from tip to tip or 8 feet 6 inches along the curve. An idea of its size as compared to the living form may be obtained from Pl. LXXVIII, fig. 1A. Its remains have been found as far south as Texas and Mississippi.
Equus complicatus ranged in the western, southern, and middle western states is well known from the Pleistocene deposits of these areas. It is characterized by teeth as large as the living horse, although it was only intermediate in size, about 14 hands high. The species somewhat resembles the ass on account of its short muzzle.
The fossil record of this class of animals is rather meager, and if the scarcity of specimens is an indication of their numbers in North America they could not have maintained themselves for a long time. It seems that they were most abundant during the Pleistocene, and had, in general, the same habitats as the existing species. Tapirus haysii was probably larger and heavier than the living species.
Plate LXXVII, fig. 2.
It has been estimated that the mastodon was as plentiful at one time as the bison. Their known range covers the entire United States northward to Lake Winnepeg and British Columbia, Alaska, and Nova Scotia. The American mastodon is distinguished by its low forehead, its short, massive limbs, very broad pelvis, the height at the shoulders not exceeding 9½ feet. It was probably covered with hair and an undercoating of wool. The tusks attained a length of 10 feet, the average in full-grown specimens being seven to eight feet long.
Plate LXXIII, fig. 2.
The northern or Siberian mammoth, Elephas primigenius, came into North America by way of the land bridge across Bearing Sea which connected Alaska with Siberia. It was adapted to a cold climate being covered with a dense coat of wool with an outer covering of long, coarse hair. In size it is the smallest of the Pleistocene elephants, about nine feet high at the shoulder. Its teeth are of the grinding type, high, cement covered, and composed of many thin plates of enamel, dentine, and cement, very much like those of the Indian elephant living today.
Plate LXXIII, fig. 1.
This form is very much like E. primigenius, except it is a very much larger form, sometimes attaining a height of 11 feet at the shoulder. The head was very high, with a peaked appearance. The tusks curved inward, sometimes overlapping in old males. The species ranged, in general to the south of the Siberian mammoth, and is found as far south as Florida and the tableland of Mexico. It is thought, since this species is found more to the south, that if the animal was covered with hair, it was not so thick as that found on the northern form.
Allen, J. A., The American bison, living and extinct: Geol.
Survey Kentucky, Mem. I pt. 2, 1876.
----, Mem. American Mus. Nat. Hist., vol. 1, pt. 4, p. 212, 1913.
Antevs, Ernst, Maps of the Pleistocene Glaciations: Bull. Geol. Soc. America, vol. 40, p. 641 fig. 4, 1929.
Bailey, Vernon, Cave life in Kentucky: Kentucky Geol. Survey, Ser. VI, vol. 49, pp---, 1931.
Carr, Lucien, On the prehistoric remains of Kentucky: Geol. Survey Kentucky Mem. I, pt. 4, pp. 1-31, 1876.
Chamberlain, R. C., and Salisbury, R. D., College Geology, Pt. II, revised, pp. 801-820, 832-842, 1930.
Coleman, A. P. The extent and thickness of the Labrador ice-sheet: Bull. Geol. Soc. America, vol. 31, pp. 319-328, 1920.
Cooper, W., Notices of Big Bone Lick: Monthly Am. Jour. Nat. Sci. vol. 1, pp. 158-174, 1831.
Cooper, W., Smith J. A., and DeKay, J. E., Report to the Lyceum of Natural History on a collection of fossil bones disinterred at Big Bone Lick, Kentucky, in September, 1830, and recently brought to New York: Am. Jour. Sci., Vol. XX. pp. 370-372, 183l.
Croghan, , Monthly Jour. Am. Geol., December, 183l.
Filson, John, Discovery, settlement, and present State of Kentucky, 1784.
Funkhouser, W. D., Wild Life in Kentucky: Kentucky Geol. Survey, Ser. VI, vol. 16, 1925.
Hay, Oliver P., The Pleistocene of North America and its vertebrated animals: Carnegie Inst. Washington, Pub. 322, p. 403, 1923.
Imlay, G., Western Tertiary of North America: pp. 47-48, 236, London, 1793.
Jillson, W. R., Glacial Pebbles in Eastern Kentucky: Kentucky Geol. Survey, Ser. VI, vol. 30, pp. 123-126, 1921.
-----, Pleistocene of northern Kentucky: Kentucky Geol. Survey, Ser. VI, vol. 31, pp. 1-80, 1929.
-----, Glaciation in Eastern Kentucky: ibid., pp. 127-135 .
-----, Early glaciation in Kentucky, ibid., pp. 137-141.
-----, Geologic map of Kentucky: Kentucky Geol. Survey, Ser. VI, 1929.
Kindle, E. M., The Discovery of Bone Lick: Kentucky Geol. Survey, Ser. VI. vol. 41. pp.-- 1931.
Leverett, Frank and Taylor, F. B., The Pleistocene of Indiana and Michigan and the history of the Great Lakes: U. S. Geol. Survey, Mon. 53, p. 62, 1915.
Lucas, F. A., The fossil Bison of North America: Proc. U. S. Nat. Mus., vol. XXI, No. 1172, pp. 775-771, pl. LXV-LXXXIV, 1899.
Lyell, Sir Charles, On the geological position of Mastodon giganteum and associated fossil remains at Big Bone Lick, Kentucky: Am. Jour. Sci., vol. 46, pp. 320-323, 1844; Geol. Soc. London, Proc., vol. 4, no. 92, 1844.
Miller, A. M., The geology of Kentucky: Kentucky Geol. Survey, Ser. V, Bull. 2, 1919.
------, Recent cave explorations in Kentucky for animal and human remains: Kentucky Geol. Survey, Ser. VI, vol. 10, pp. 107-113, 1923.
Osborn, H. F., The Age of Mammals: McMillan, pp. 478-80, 1910.
Osgood, Wilfred H., Smithsonian Mis. Coll., vol. XLVIII, pp. 113-185, pl. 37-42, 1905.
Scott, William B., A history of land animals in the Western Hemisphere: McMillan, 1913.
Shaler, N. S., On the age of the bison in the Ohio Valley: Geol. Survey Kentucky, Mem. I, pp. 232-236, 1876.
------, On the antiquity of caverns and cavern life in the Ohio Valley: ibid., pp. 1-13, 1876.
Silliman, Benj., Am. Jour. Sci., vol. XX., pp. 371-372, 1831.
Webb, William S., and Funkhouser, William D., Ancient Life in Kentucky: Kentucky Geol. Survey, Ser. VI, vol. 34, pp. 40-46, 1928.
Wright, G. F., The glacial boundary in western Pennsylvania, Ohio, Kentucky, Indiana, and Illinois: U. S. Geol. Survey, Bull. 58, 1890.
1Jillson, W. R.,
Glaciation in Eastern Kentucky: Ky. Geol. Surv., Ser. VI., Vol. 30, p. 134.
2Chamberlain, T. C. and Salisbury, R. D., College Geology, Pt. II, Revised p. 834. 1930.
3Chamberlain, T. C., and Salisbury, R. D., op. cit., p. 835.
4The list of the invertebrates is taken from a manuscript on the geology of Henderson County, by C. V. Theis.
5Webb, W. S. and Funkhouser, W. D., Ancient Life in Kentucky, Ky. Geol. Surv., Ser. VI., Vol. 34, pp. 40-46, 1928.
6Jillson, W. R., Pleistocene Proboscideans Within the Cumberland Plateau in Kentucky: Bull. Geol. S. Am., vol. 40, No.1, p. 253, 1929.
7Hays, _, _., Proc. Biol. Soc. Wash., March 20, 1922.
8Zittel, Karl, Handbuch der Paleontologie, Bd. IV, p. 132, 1893.
Explanation of Plate LXXII
Explanation of Plate LXXIII
Explanation of Plate LXXIV
Explanation of Plate LXXV
Explanation of Plate LXXVI
Explanation of Plate LXXVII
Explanation of Plate LXXVIII