Mr. Pengelly thinks it possible, but not proved, that the lower breccia of Kent's Cavern may be interglacial or preglacial in age. One case only is known where a human bone has been found in a cavern under deposits supposed to be of the nature of the glacial drift. It is that of the Victoria Cave, at Settle, in Yorkshire. At this place a human fibula was found under a layer of boulder clay. But there are too many chances of this bone having come into this position by some purely local accident to allow us to attach much importance to it until future discoveries shall have supplied other instances of the kind.[138] I may close this survey of the cave deposits with a summary of the results of M. Dupont, as obtained from two of the caves explored by him, that of Margite and that of Frontal. In the first of these caverns, resting on rolled pebbles which covered the floor, were four distinct layers of river mud deposited by inundations, and amounting to two yards and a half in thickness. In all of these layers were bones. The lowest contained rude flint implements, and bones of the mammoth, rhinoceros, bear, horse, chamois, reindeer, stag, and hyena. In the overlying deposits are some flint implements of more artistic form and a greater prevalence of the bones of the reindeer. In the second cave, that of Frontal, over a similar deposit of alluvial mud of the mammoth age, was found a sepulchre containing the remains of sixteen individuals, of the second or diminutive Lappish race before referred to. The door of the cave had been closed by these people with a slab of stone, and in front was a hearth for funeral feasts, built on the deposits of the mammoth age, and containing bones of animals all recent or now living in Belgium, and without any traces of the bones of the extinct quadrupeds. This burial-place belonged to the Neocosmic yet prehistoric race which replaced the Palaeocosmic men of the mammoth age. What is the absolute antiquity of the Palaeocosmic age in Europe? We have no monumental or historical chronology to answer this question, but only the measures of time furnished by the accumulation of deposits, by the deposition of stalagmite, by the gradual extinction of animals, and by the erosion of valleys and other physical changes. These somewhat loose measures have been applied in various ways, but the tendency of geologists, from the prevalence of uniformitarian views, and the prejudice created by familiarity with the long times of previous geologic periods, has been to assign to them too great rather than too little value, both as measures of time and as indicating a remote antiquity.