At a point 7 miles southeast of Knoxville (fig. 23, 9) Professor S. W. McCallie reported the finding of a mastodon tooth beneath 30 inches of clay. At Lookout Mountain (p. 395, fig. 23, 10) have been secured a tooth of a horse, probably Equus littoralis (p. [201]), remains of tapir and probably of Mylodon (p. [43]). Just where the horse-tooth was found is not known. The tapir was found in a cave on the left bank of Tennessee River, 0.25 mile below the mouth of Chattanooga Creek (Mercer, as cited above; also in Amer. Naturalist, vol. XXVIII, p. 355). Mercer’s accounts are brief and were intended only as preliminary reports. From him, through Miss Harriet Newell Wardle, of Philadelphia, the writer has received a letter in which are given some details about the investigation of this cave in 1893 and 1896.
Dr. Mercer extended his trench inward from the entrance a distance of about 50 feet and downward to the rocky bottom of the cave. He recognized the presence of three layers, as follows: (1) top layer, from 6 to 8 inches deep, containing relics of both white man and Indian; (2) middle layer, about 2 feet thick, containing evidence of Indian only; (3) red cave earth, varying from one to several feet in thickness, according to the uneven conditions of the cave floor. This latter layer was subdivided into an upper zone (a) about a foot deep, which showed evidences of intrusion of bones and refuse from the overlying layer, and (b) the undisturbed red earth which contained bones of bats and perhaps of some other animals. In the upper zone (a) of the red-earth layer Mercer found a jawbone and loose teeth of Tapirus haysii (p. [209]) and a jawbone of Mylodon (p. [43]) without teeth, both as identified by Professor Cope. Later, Cope became doubtful as to the Mylodon bone. In this upper zone of red earth, “within a few varying inches of the depth of the tapir specimen above or below it,” Mercer found bones of cave rats (Neotoma), marmot (Marmota), squirrel, deer, opossum, teeth and fragments of the skull of a large unidentified mammal, a small and a large bird, wild turkey, two species of turtles, frogs, and drum-fish. The skull and other bones of the large unidentified mammal had plainly been cracked to secure the marrow, and were otherwise crushed and splintered. Also, as many as 493 hornstone chips were found, besides bones rubbed to a point, and 10 potsherds. It becomes a question how the tapir bone and teeth and perhaps the bone of the mylodon and the evidences of the Indian’s presence got into this upper layer of red earth. Mercer “thought it reasonable to conclude that the tapir had been intruded into the red earth from the upper layer and had been in contact with the Indians.” This appears to indicate the idea that the tapir had existed there at a late period, probably after the Pleistocene; but the evidences appear to show that this animal lived in the United States not later than about the Sangamon stage of the Pleistocene. It is more probable that the tapir remains had not been disturbed and that the relics of man had, by some means, made their way down into the red earth. There remains also the possibility that Indians and tapirs and mylodons had lived together in that region during the middle of the Pleistocene and while the upper foot of red clay was being deposited. The presence of the other animals mentioned by Mercer does not disprove this possibility, for all of them pretty certainly existed there during the middle Pleistocene.
Not far from Elroy, Van Buren County (fig. 23, 11) there is an interesting cavern known as Bigbone Cave. This and the bones which it has furnished are now to be described.
Mercer (Proc. Amer. Philos. Soc., vol. XXXVI, pp. 36–70) found that in the greater part of this cave the nitrous earth that had formed the floor had been removed to such an extent that on the walls its stains remained at a height of one’s waist. Wherever any of this deposit remained it was exceedingly dry and any disturbance of it produced a cloud of dust. It appears to have consisted mostly of the dung and excretions of animals, such as bats and cave rats. The preservation of the cartilage and horny sheaths of the claw was due to this dryness of the atmosphere. Where Mercer found the bones he recognized four layers, to represent which he published a figure (op. cit., p. 47, fig. 4). This is here reproduced with unimportant changes (fig. 24). On top there was a layer from 2 to 3 inches thick which had resulted from the disturbance produced by the passing of white men and possibly to some extent of Indians. With the dust were mingled remains of charred vegetable substances that had been used as torches.
Fig. 24.—Diagram showing a vertical section of the gallery in Bigbone Cave near Elroy, Van Buren County, Tenn. Adapted from Mercer.
The second layer was 2 to 5 feet deep and consisted almost entirely of well-preserved dried excrements of cave rats (Neotoma) and of porcupines (Erethizon). In it were observed nuts, sticks, fur, and moss. The only animal remains found in this layer were the bones of Megalonyx (p. [42]), quills and coprolites of Erethizon dorsatum, coprolites and a jaw of a cave rat referred to Neotoma magister, and jaws of two bats, Adelonycteris fuscus and Myotis subulatus (Vespertilio gryphus of Mercer). Some traces were found of an undetermined herbivorous mammal about as large as a bear. With the lot of Megalonyx bones from this cave which were described by Harlan there were remains referred to Bos (Bison), Ursus, Cervus (Odocoileus?), and a human metatarsal; but these were reported as having been picked up on the surface and may therefore have belonged to quite recent skeletons.
Besides the animal remains found by Mercer in his second layer, there were present quantities of vegetable matter belonging to several species. All, however, were forms yet living in that region.
Mercer’s third layer appears to have consisted of dry excrements which had become somewhat hardened. Its thickness was a foot. In it were found vegetable matter, some bat jaws and fur, and the carcass of a “window fly.” The fourth layer consisted of a fine water-laid clay which on drying had contracted and broken up into small angular masses. The interstices appear to have been filled by materials soaking down from the upper layers of excrement. No organisms were found in it.
Mercer concluded that the sloth remains were geologically recent, and this may be true. Megalonyx jeffersonii has been found in the northern States in deposits overlying the Wisconsin drift, and it is quite reasonable to suppose that the animal existed in Tennessee up to as late a time as it did in Ohio and Illinois. The persistence of the cartilages of the sloth, and the framework of the window fly which lay below the sloth bones, naturally suggests a comparatively short time; but if, through the dryness of the cave, they could endure a thousand years, they might possibly endure several thousand. One must consider also the length of time required for 1.5 or 2 feet of cave floor to be built up from the excrements of bats, porcupines, and cave rats, but there is no reason to refer the time back further than about the close of the Wisconsin stage.