The caves also undoubtedly embody in the contents of their silt and stalagmite the industrial implements of a later period than that of the river-gravels; and, as in the case of Kent’s Cavern, even preserve the evidence of a succession of occupants belonging to distinct eras, and probably to essentially diverse races of men. But it is only in exceptional cases of special interest that the cave-drift discloses traces of actual habitation, the refuse heaps of the kitchen, the broken or stray tools, and even the flint-cores, hammer-stones, and flint-chips, which indicate the workshop of the ancient tool-maker. Mr. Evans figures hammer-stones of various kinds, made of diverse pebbles and of chipped flint; and others from the French caves consist of flint-cores with the prominent surfaces worn round by their use as hammer-stones in the process of chipping the flint into the desired forms. One of this class of implements now in my possession, of light grey flint, and bearing manifest traces of long use, was turned up in a ploughed field in Licking County, Ohio. Another example in my collection was presented to me by Mr. W. L. Merrin, who picked it up in the vicinity of one of the pits on Flint Ridge, among the broken flakes and nodules which showed where the old flint miner had been at work. The cave deposits embedded animal remains and human implements in part by the same processes which in neighbouring river-valleys were burying the works of man alongside of the bones of the largest fossil mammalia. In the former, at times, the silting up was by a process sufficiently gentle to preserve unharmed the minuter traces of the cave-dweller and his arts; but as a rule there have remained to us from that remote Palæotechnic era, only the larger and ruder implements, corresponding as it were to the axe of the woodman, and the mattock or plough of the field labourer, which were alone capable of withstanding the violence of floods, and the like elements of geological reconstruction.
Enough survives to us, from the disclosures of a different character in the actual cave-dwellings of the Men of the Drift, to confirm the idea that we have as yet obtained a very partial glimpse of the arts of that remote dawn; and that we may watch with interest every fresh disclosure calculated to lessen the wonder excited by the large lanceolate or ovate worked flints of that era: rude enough at times to be ascribed to some irrational Caliban, rather than to a human artificer. It may perhaps be thought that I have yielded too ready credence to a fanciful analogy; but as I explored the deserted flint pits of the Shawnees, and the ancient quarry of the Ohio Mound-Builders, or picked up in the furrows of their desecrated earthworks huge half-formed ovate and spear-shaped blocks of hornstone akin to those of the European drift, it seemed to me like a glimpse of light illuminating the obscurity of that remote dawn.