ANCIENT GLACIERS IN EASTERN HEMISPHERE. 1S5 



they are identical in character. What may be their rela- 

 tions in time remains to be determined." 



The physical geography of Europe is so different from 

 that of America, that there was a marked difference in 

 the secondary or incidental effects of the Glacial period 

 upon the two regions. In America the continental area 

 over which the glaciers spread is comparatively simple in 

 its outlines. East of the Rocky Mountains, as we have 

 seen, the drainage of the Glacial period was, for a time, 

 nearly all concentrated in the Mississippi basin, and the 

 streams had a free course southward. 



But in Europe there was no free drainage to the south, 

 except over a small portion of the glaciated area in central 

 Eussia, about the head-waters of the Dnieper, the Don, 

 and the Volga ; though the Danube and the Ehone af- 

 forded free course for the waters of a portion of the great 

 Alpine glaciers. But all the great rivers of northern 

 Europe flow to the northward, and, with the exception of 

 the Seine, they all for a time encountered the front of the 

 continental ice-sheet. This circumstance makes it dif- 

 ficult to distinguish closely between the direct glacial 

 deposits in Europe and those which are more or less 

 modified by water action. At first sight it would seem 

 also somewhat hazardous to attempt to correlate with any 

 portion of the Glacial period the deposition of the gravelly 

 and loamy deposits in valleys, which, like those of the 

 Seine and Somme, lie entirely outside of the glaciated 

 area. 



Upon close examination, however, the elements of 

 doubt more and more disappear. The Glacial period was 

 one of great precipitation, and it is natural to suppose 

 that the area of excessive snow-fall extended considerably 

 beyond the limit of the ice-front. During that period 

 therefore, the rivers of central France must have been an- 

 nually flooded to an extent far beyond anything which is 

 known at the present time. Since these rivers flowed to 



