►ScHARFF — On the Origin of the Euvopean Fauna. 457 



clay. Mr. Sjogren (78), however, has shown that hitherto all the- 

 observations have pointed to the fact that the former do not overlie 

 the boulder-clay, but occur side by side, a circumstance which cer- 

 tainly speaks for the contemporaneousness of the two formations. 



We have to choose consequently between one of two alternatives — 

 either I^orthern Eussia was covered by a mass of ice, and then Siberia 

 must have been practically uninhabitable, or tlie climate of both 

 Europe and Siberia were more temperate than they are now. In the 

 face of the numerous works which have been written in recent years 

 by Prof. J. Geikie, Prof. Penck, Mr. Palsan, Prof. Bonney, and many 

 other distinguished geologists, on the proofs of a cold and even Arctic 

 climate in Europe during the Glacial Period, it may seem futile to 

 doubt what is put forward as a well-established fact. But with 

 Tcherski I hare been led to conclude, that Siberia had a compara- 

 tively mild climate in Pleistocene times. jSTorthern Europe could 

 not — that being the case — have been glaciated in the manner above 

 described. Before following the migrations of the Siberian fauna to 

 Europe, I must therefore dwell for a little while on the origin of the 

 Continental boulder- clay. 



What is now looked upon as such an established fact, was ex- 

 plained in cj^uite a different manner fifty years ago. Murchison, 

 de Yerneuil, and von Keyserling, who studied these identical Eussian 

 boulder-clays, which are now regarded as ground moraines of huge 

 glaciers, came to the conclusion that they were laid down by the sea, 

 and as regards the origin of these clays the following is their verdict 

 (59, p. 536) : — " If, as we believe, it is impossible to imagine that 

 the detritus in question should have been carried across the Baltic 

 Sea, and from the level of that sea several hundred miles up the 

 streams, under any coneeivable terrestrial conditions, it follows from 

 these considerations alone that all theories to account for the move- 

 ment of such bodies over the dry surface of the earth are inadmissible. 

 The hypothesis of glaciers advancing up-hill for the distance of 700- 

 800 miles involves, in fact, a physical absurdity." The present 

 champion of the theory of the marine origin of the boulder-clay in 

 Germany, Mr. Berendt has, in a lengthy essay, published about sixteen 

 years ago, given his reasons for still adhering to the old views (6). 



A good many of the facts brought forward by this writer seem to 

 be equally well explained by either the terrestrial or tlie marine 

 theory; but Prof. Penck (66 3) in an article, wiitten in answer to 

 Mr. Berendt, certainly adduces several, which, I believe, have never 

 been satisfactorily elucidated by the marine mode of origin of the 



