Page:Early Man in Britain and His Place in the Tertiary Period.djvu/41

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close of the Secondary age, as we have observed in the preceding chapter, was marked by great changes in the physical geography of Europe. The cretaceous rocks, which had been formed at the bottom of a deep sea, were lifted up above the waves, and plants and animals hitherto unknown appeared on the new continent. The new invaders took possession of the land, the air, and the sea, and brought about as marked a change in the European fauna as that in geography which had preceded their arrival.

It is very probable that the elevation of the bottom of the sea, by which this immigration of new forms became possible, was accompanied by a corresponding depression of a neighbouring tract of land, like that