This is Tcherski's explanation of the extraordinary events which he has chronicled, after years of the most arduous labour and under conditions of peculiar hardship. And though his work cannot be over-estimated, and his opinions should receive the most careful consideration, yet I fear the explanation will not be looked upon as entirely satisfactory. Every one will agree with him that the climate of Siberia must have been greatly moister in pliocene and pleistocene times than it is now. The Aralo-Caspian covered a vast area of South-western Siberia. Freshwater basins existed along the east of the Ural Mountains, while Central Asia was studded over with a number of large lakes, which have now almost entirely vanished. But that the generally assumed refrigeration of Europe must have had a chilling effect on the Siberian atmosphere seems to me evident. That the whole of Northern Europe should have been made uninhabitable owing to the advance of the Scandinavian ice-sheet, while North Siberia at the same time supported forests, meadows, and a temperate fauna, is incredible. At the approach of winter, at any rate, the animals would have been driven southward for thousands of miles to seek shelter from the snows and cold and to obtain nourishment, and it would scarcely have been possible for them to undertake such vast migrations at every season. Professor James Geikie's suggestion (p. 706), that the Mammoth and Woolly Rhinoceros could have survived the Pleistocene Epoch in Southern Siberia, does not appear to solve the problem, as that part of Asia must have participated in the great cold which is said to have prevailed all over Europe.
Let us now concede, for the sake of argument, that the current views regarding the pleistocene climate of Europe are correct. We are told by Professor Geikie that the climate of Scotland during part of the Pleistocene Epoch was so cold, that the whole country was buried underneath one immense _mer de glace_, through which peered only the higher mountain-tops (p. 67). If this was the state of climate in close proximity to the Atlantic, it must probably have been still more severe on the European continent. Now at the present time Siberia has the reputation of being the coldest country in the world, and the mercury of the thermometer is said to remain frozen for weeks during winter, even in the south.