| Irish Elk | |x|x|x| | |x| | x | | |x | | | | | |x|x| x | | | | | | | | | | | | | | | | | | | | | | | |_Cervus tarandus_-- | | | | | | | | | | | | | | | | | | | | | | Reindeer |x|x|x|x|x| |x|x| x |x|x|+ |x |+|x|x| |x|x| x | | | | | | | | | | | | | | | | | | | | | | | |_Hippopotamus amphibius_ | | | | | | | | | | | | | | | | | | | | | | (_var. major_)-- |x| | | | | | | |(?)| | | | | | | | | |x| x | | Hippopotamus | | | | | | | | | | | | | | | | | | | | | +---------------------------+-+-+-+-+-+-+-+-+---+-+-+--+--+-+-+-+-+-+-+---+ _Cave Fauna the same as River-bed Fauna._ If this list[237] of animals from the caves be compared with that of the river-deposits of Britain and the continent, it will be seen that the same fauna is present in both, and that they are therefore of the same geological age.[238] This was the conclusion to which Dr. Falconer was led by the examination of the caves of Gower, and it has been confirmed by every subsequent discovery. _The Pleistocene Coast-line of North-Western Europe._ The identity of the British pleistocene fauna with that of the continent, leads to the conclusion that in the pleistocene age Britain was connected with the adjacent countries by a bridge of land, over which the wild animals had free means of migration. And this might be brought about by a comparatively small elevation of the area. The soundings show that Britain and Ireland constitute merely the uplands of a plateau now submerged to the extent of about 100 fathoms, on the side of the Atlantic. On the east it extends at a depth of from twenty to fifty fathoms, in the direction of Belgium; and on the south it is only sunk from twenty to forty fathoms below the sea-level. Immediately to the westward of this line the sea deepens so suddenly, that there is scarcely any difference between the lines of 100 and of 200 fathoms, and the depth rapidly increases to 2,000. Were this plateau elevated above the sea to an extent of 100 fathoms, the tract shaded in the map (Fig. 126) would unite the British Isles to the continent, and the Thames and other rivers on the eastern coast would unite with the Elbe and the Rhine to form a river debouching on the North Sea, somewhat after the manner which I have represented by taking the deepest line of soundings. The Straits of Dover would then be the watershed between this valley of the German Ocean, as it may be termed, and that of the English Channel, in which the Seine and the Somme and other French rivers joined those of the south coast, and ultimately reached the Atlantic. Evidence that the latter river flowed in the course assigned to it in the map is afforded by the discovery of the fresh-water mussel (_Unio pictorum_), recorded by Mr. Godwin Austen[239] to have been dredged up by Captain White from a depth of from 50 to 100 fathoms, not