It was ascertained that in very early times, but yet long after the Drift Period, the dwellers near by had had a predilection for using the caves as burial-places, so that the fact of human bones coming together with bones of Drift animals in the floor of the same cave is easily explained. Moreover, it was found that from the earliest times down to the present day the caves had been used by hunters, herdsmen, and others as places of shelter in bad weather, as cooking-places, and sometimes even--especially in very early times--as regular dwelling-places for longer periods, so that refuse of all kinds, and often of all ages and forms of civilisation that the land has seen from the Drift Period down to modern times, must have got into the floors of the caves. If these were damp and soft, the remains of every century were trodden in and got to lie deeper and deeper, so that, for instance, the fragments of a cast-iron saucepan were actually found right among the bones of regular Drift animals in a cave in Upper Franconia. [Sidenote: The Caves do not Prove Drift Man] The discoveries of human remains in caves appeared discredited by this, and to be of no value as proofs of the co-existence of man with the Drift fauna. And indeed this position must practically be still taken at the present day: all cave-finds are to be judged with the greatest caution. They in themselves would never have been sufficient to establish the existence of Drift Man, although, according to the general change in scientific thought that led to the overthrow of Cuvier’s theory, Drift Man is now just as much a postulate of science as was formerly the case for the opposite assumption. [Sidenote: Finding the First Drift Man] The first sure proofs were adduced in France by Boucher de Perthes, in the Drift beds of the Somme valley, near Abbeville, at the end of the third decade of the nineteenth century. Fully recognising the inadequacy of proof given by cave-finds, he had sought for the relics of man in the undisturbed Drift beds of gravel and coarse sand that contains the bones of Drift animals, which by their covering and depth precluded all suspicion of having been subsequently dug over. And he was successful. He had argued in exactly the same manner as Esper had formerly done, but with better right. In the stratified Drift formations every period is sharply defined by the layers of differently coloured and differently composed strata horizontally overlying one another. Here the proofs begin. They are irrefutable if it is shown that the relics of man have been there since the deposit. Being no less immovable than this stratum in which they lie, as they came with it, they were likewise preserved with it; and as they have contributed to its formation, they existed before it. [Sidenote: The Overthrow of Cuvier’s Famous Theory]