The record of the three early glaciations is not fully written in the animal and plant life, but it appears to be found in the river channels. Both in England and France these channels attest flooded conditions during the earlier glaciations, in which large quantities of gravels and sands were transported, and it is of these materials that the 'high terraces' were built up. It is chiefly the geologic evidence which establishes the Pre-Chellean date. Geologic and climatic lines of evidence in France indicate that the Pre-Chellean culture is first witnessed during the beginning of Third Interglacial times. This is the opinion of Boule, Haug, Obermaier, Breuil, Schmidt, and many other geologists and archæologists. That the first Palæolithic flint workers found their way into western Europe during the early part of Third Interglacial times is consistent with our observations on the sequence of climate, on the formation of the 'low river terraces,' where palæoliths of the earliest type occur, as well as with the general succession of mammalian life throughout the climatic changes of this interglacial period. It would appear, in explanation of the facts cited above regarding the fossil mammals, that when the Pre-Chellean flint workers established their camps along the valley of the River Somme in northern France a very genial climate prevailed in this region, favorable even, as we shall see, to the survival of some of the Pliocene types of mammals, such as the sabre-tooth tiger and the Etruscan rhinoceros. During the early part of the Third Interglacial Stage the climate, so far as we can judge by the unchanged aspect of the animal life, remained of the same warm temperate character. Two only of the surviving Pliocene forms, namely, the sabre-tooth tigers and the Etruscan rhinoceroses, became rare or extinct. From evidence afforded in Kent's Hole, Devonshire, Dawkins is led to believe that the sabre-tooth tiger survived in Britain until Postglacial times. All the rest of the animal world, both the African-Asiatic and the Eurasiatic mammals, continued to flourish throughout western Europe. Not until the latter part of Acheulean times do we discover proofs of a decided change of climate; in the approach of arid conditions similar to those of the steppes of western Asia there was a renewal of the great dust-storms and depositions of 'loess,' such as had previously occurred toward the close of Second Interglacial times; this was followed by the still colder climate of the fourth glaciation, which corresponds with the closing period of Lower Palæolithic culture.