The best authorities also suppose that the reign of snow and ice was broken by at least one return (possibly more) of genial climate, when animals and plants from the south again visited the countries of Northern Europe—only, however, to be once more driven forth by a return of arctic cold. But finally, before the increasing warmth of a genial Climate, the glaciers vanished, not to return again, and the Glacial Age became merged in that of the present. It is no longer a question that man lived in Europe during the largest portion of this age, if not from the beginning. It is necessary, then, to come to a clear understanding of the successive stages of this entire age, and to trace the wonderful cycles of climate—the strange mutation of heat and cold, which must have exerted a powerful influence on the life, both animal and vegetable, of the period—and see when we first find decisive proofs of man’s presence, and learn what we can of his condition. The map of Europe, at the close of Pliocene times and the commencement of the Glacial Age, is of interest to us in several ways. From this it will be seen that it was considerably more elevated than at the present. As this is no fancy sketch, but is based on facts, it is well to outline them. Without the aid of man, land animals can not possibly pass from the mainland of a continent to an island lying some distance off the shore. But it is well known that animals like the rhinoceros, and several others, wandered as well over the surface of the British Islands as on the adjacent coast of Europe. We are therefore compelled to assume, that at that time the English Channel and the Irish Sea were not in existence. This necessitates an elevation of at least four hundred feet, which would also lay bare a large portion of the North Sea.5 In proof of this latter statement is the fact, that, at a distance from land in the North Sea, fishermen at the present day frequently dredge up bones and teeth of animals that then roamed in Europe.6 Map of Europe.