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.
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.
The Overthrow of Cuvier’s Famous Theory
That is the line of thought according to which Boucher de Perthes was able, in 1839, to lay before the leading experts in Paris—at their head Cuvier himself—his discoveries proving the former existence of Drift man. But his demonstrations were not then sufficient to break the old ban of prejudices that were apparently founded on such good scientific bases; his proofs of the presence of man in the Somme valley at the time of the Drift, contemporaneously with the extinct Drift animals, were ridiculed. It was twenty years before these long-neglected discoveries in the Somme valley concerning the early history of man were recognised by the scientific world. This was only made possible by Lyell, whose authority as a geologist had risen above Cuvier’s, placing the whole weight of it on Boucher’s side, after having personally travelled over the Somme valley three times in the year 1859, and having himself examined all the chief places where relics of Drift Man had been discovered. According to Lyell’s description, the Somme valley lies in a district of white chalk, which forms elevations of several hundred feet in height. If we ascend to this height we find ourselves on an extensive tableland, showing only moderate elevations and depressions, and covered uninterruptedly for miles with loam and brick earth about five feet thick and quite devoid of fossils. Here and there on the chalk may be noticed outlying patches of Tertiary sand and clay, the remains of a once extensive formation, the denudation of which has chiefly furnished the Drift gravel material in which the relics of man and the bones of extinct animals lie buried. The Drift alluvial deposit of the Somme valley exhibits nothing extraordinary in its stratification or outward appearance, nor in its composition or organic contents. The stratum in which the bones of the Drift fauna are found intermingled with the relics of man is partly a marine and partly a fluviatile deposit. The human relics in particular are mostly buried deep in the gravel; almost everywhere one has to pass down through a mass of overlying loam with land shells, or a fine sand with fresh-water molluscs, before coming to beds of gravel, in which the relics of Drift Man are found.
Animals of the Ice Age
Everything shows that the relics of man are here in a secondary situs, deposited in the same way as the bones of extinct animals and the whole geological material in which everything is embedded. That is the reason why the finds cannot be more exactly dated. They doubtless belong to the general drift, but whether to the Postglacial Period, or the warmer Interglacial Period, cannot be decided. The fauna admits of no absolute limitation, owing to its being mixed from both periods. The mammalia most frequently found in the strata in question are the mammoth, Siberian rhinoceros, horse, reindeer, ure-ox, giant fallow-deer, cave-lion, and cave-hyena. In very similar Drift deposits of the Somme near Amiens traces of man were found beside the bones of the hippopotamus and the elephant.
These animals were chiefly prevalent in France and Germany in the Preglacial and Interglacial Periods of the Drift. Part of the animal remains found near Abbeville, particularly those of the cave-lion and cave-hyena, also point to the warmer Interglacial Period; on the other hand, the mammoth, Siberian rhinoceros, and especially the reindeer, appear to indicate with all certainty the second Glacial and Postglacial Periods. The bones of the older Drift animals may have been washed out of other primary situs; the reindeer had certainly already taken possession of those parts of France when the relics of man were embedded.
