Such evidence is afforded by the valleys which radiate from the great central boss of France in the Auvergne. The hill of Perrier had long been known as a rich site of the fossil remains of the extinct Pliocene fauna, and its section has been carefully studied by some of the best French geologists, whose results are summed up as follows by Hamy in his Palæontologie humaine—
"The bed-rock is primitive protogine, which is covered by nearly horizontal lacustrine Miocene, itself covered by some metres of fluviatile gravels. Above comes a bed of fine sand, a mètre thick, which contains numerous specimens of the well-known mammalian fauna of the Lower Pliocene, characterized by two mastodons (M. Armenicus and M. Borsoni). Then comes a mass of conglomerates 150 mètres thick, consisting of pebbles and boulders cemented by yellowish mud; and above this a distinct layer of Upper Pliocene characterized by the Elephas Meridionalis.
"The boulders, some of which are of great size, are all angular, never rounded or stratified, often scratched, and mostly consisting of trachyte, which must have been transported twenty-five kilomètres from the Puy de Dôme. In short, the conglomerate is absolutely indistinguishable from any other glacial moraine, whether of the Quaternary period or of the present day. It is divided into three sections by two layers of rolled pebbles and sands, which could only have been caused by running water, so that the glacier must have advanced and retreated three times, leaving each time a moraine fifty mètres thick, and the whole of this must have occurred before the deposit of the Upper Pliocene stratum with its Elephas Meridionalis and other Pliocene mammals."
The importance of this will presently be seen, for the Elephas Meridionalis is one of the extinct animals which is most directly connected with the proofs of man's existence before the Quaternary period. It is also important as confirming the immense time which must have elapsed between the date of the first and second maxima of glacial cold, and thus adding probability to the calculations derived from Croll's periods of maximum and minimum eccentricity.
The three advances and retreats of the great Perrier glacier also fit in extremely well with the calculated effects of precession during high eccentricity, as about three of such periods must have occurred in the period of the coming on, culminating, and receding of each phase of maximum eccentricity.
This evidence from Perrier does not stand alone, for in the neighbouring valleys, and in many other localities, isolated boulders of foreign rocks which could only have been transported by ice, are found at heights considerably above those of the more recent moraines and boulders which had been supposed to mark the limit of the greatest glaciation. Thus on the slopes of the Jura and the Vosges, boulders of Alpine rocks, much worn by age, and whose accompanying drifts and moraines have disappeared by denudation, are found at heights 150 or 200 mètres above the more obvious moraines and boulders, which themselves rise to a height of nearly 4000 feet, and must have been the front of glaciers from the Alps which buried the plain of Switzerland under that thickness of solid ice.
The only possible alternative to this evidence from Perrier would be to throw back the duration of the Quaternary and limit that of the Pliocene enormously, by supposing that all the deposits above the great glacial conglomerate or old moraine, are inter-glacial and not Tertiary. This is, as has been pointed out, very much a question of words, for the phenomena and the time required to account for them remain the same by whatever name we elect to call them. But it still has its importance, for it involves the fundamental principle of geology, that of classifying eras and formations by their fauna. If the Elephas Meridionalis is a Pliocene and not a Quaternary species, we must admit, with the great majority of continental geologists, that the first and greatest glaciation fell within the Pliocene period. If, on the other hand, this elephant is, like the mammoth, part of the Quaternary fauna, we may believe, as many English geologists do, that the first glacial period coincided with and probably occasioned the change from Pliocene to Quaternary, and that everything above the oldest boulder-clays and moraines is not Tertiary but inter-glacial.
As bones of the Elephas Meridionalis have been frequently found in connection with human implements, and with cuts on them which could only have been made by flint knives ground by the human hand, it will be seen at once what an interest attaches to this apparently dry geological question, of the age of the great southern elephant.
The transition from the mastodon into the elephant took place in the Old World (for in America the succession is different) in the Pliocene period. In the older Pliocene we have nothing but mastodons, in the newer nothing but elephants, and the transition from the older to the newer type is distinctly traced by intermediate forms in the fossil fauna of the Sewalek hills. The Elephas Meridionalis is the oldest known form of true elephant, and it is characteristic of all the different formations of the Upper Pliocene, while it is nowhere found in cave or river deposits which belong unmistakably to the Quaternary. It was a gigantic animal, fully four feet higher than the tallest existing elephant, and bulky in proportion. It had a near relation in the Elephas Antiquus, which was of equal size, and different from it mainly in a more specialized structure of the molar teeth, and the remains of this elephant have been found in the lower strata of some of the oldest bone-caves and river-silts, as to which it is difficult to say whether they are older or younger than the first glacial period. The remains of a pygmy elephant, no bigger than an ass, have also been found in the Upper Pliocene, at Malta and Sicily, and those of the existing African elephant in Sicily and Spain. It would seem, therefore, that the Upper Pliocene was the golden age of the elephants where they were most widely diffused, and comprised most species and most varieties, both in the direction of gigantic and of diminutive size. But in passing from the Pliocene into the Quaternary period, they all, or almost all, disappeared, and were superseded by the Elephas Primigenius, or mammoth, which had put in a first appearance in the latest Pliocene, and became the principal representative of the genus Elephas in Europe and Northern Asia down to comparatively recent times.
This succession is confirmed by that of the rhinoceros, of which several species were contemporary with the Elephas Meridionalis, while the Rhinoceros tichorinus, or woolly rhinoceros, who is the inseparable companion of the mammoth, appeared and disappeared with him.