After the old stalagmite floor above mentioned was formed, the cave again received deposits of muddy water and stones; but now a change occurs in the remains embedded. This stony clay, or "cave earth," has yielded an immense quantity of teeth and bones, including those of the elephant, rhinoceros, horse, hyena, cave bear, reindeer, and Irish elk. With these were found weapons of chipped flint, and harpoons, needles, and bodkins of bone, precisely similar to those of the North American Indians and other rude races. The "cave earth" is four feet or more in thickness. It is not stratified, and contains many fallen fragments of rock, rounded stones, and broken pieces of stalagmite. It also has patches of the excrement of hyenas, which the explorers suppose to indicate the temporary residence of these animals; and besides fragments of charcoal scattered in the mass, there is in one spot, near the top, a limited layer of burned wood, with remains which indicate the cooking and eating of repasts of animal food by man. It is clear that when this bed was formed the cavern was liable to be inundated with muddy water, carrying stones and perhaps some of the bones and implements, and breaking up in places the old stalagmite floor.[137] One of the most puzzling features, especially to those who take an exclusively uniformitarian view, is that the entrance of water-borne mud and stones implies a level of the bottom of the water in the neighboring valleys of nearly one hundred feet above its present height. The cave earth is covered by a second crust of stalagmite, less dense and thick than that below, and containing only a few bones, which are of the same general character with those beneath, but include a fragment of a human jaw with teeth. Evidently when this stalagmite was formed the influx of water-borne materials had ceased, or nearly so; and Mr. Pengelly appears to affirm, though without assigning any reason, that none of these bones could, like the masses of stalagmite, have been lifted from lower beds, or washed into the cave from without. The next bed marks a new change. It is a layer of black mould from three to ten inches thick. Its microscopic structure does not seem to have been examined; but it is probably a forest soil, introduced by growth, by water, by wind, and by ingress of animals, all of them modern, and contains works of art from the old British times before the Roman invasion up to the porter bottles and dropped half-pence of modern visitors. Lastly, in and upon the black mould are many fallen blocks from the roof of the cave.