740 THE JOURNAL OF GEOLOGY. 



tion of this second series of gravels, there was a long period of erosion 

 and weathering, during which deep valleys were cut in the high terrace 

 gravels. This period of erosion corresponds with the second intergla- 

 cial epoch of the region. Later, a third series of glacial gravels was 

 deposited in the valleys cut out of the second series. This third 

 series may be traced into direct connection with the terminal 

 moraines in the mountain valleys. The foregoing sequence was first 

 established by Penck for Upper Bavaria, but it has been found to hold for 

 all the Alpine Vorland between the Rhine and the Traun. By Professor 

 Geikie these three glacial epochs of Switzerland are believed to cor- 

 respond to the first three glacial epochs of Northern Europe. 



The argument for the tripartite division of the glacial deposits of 

 Switzerland as stated by Professor Geikie, seems strong. The evidence 

 has been gathered with great care by those on whose conclusions we 

 have learned to rely. Until it is decided how far the ice must have 

 retreated, relative to earlier and later advances, and how long it must 

 have stayed in retreat, in order that a re-advance shall constitute a 

 new ice epoch, there is of course chance for discussion as to whether 

 these separate series of glacial deposits represent distinct glacial 

 epochs. But from Professor Geikie's exposition, there can hardly be 

 a doubt that the three subdivisions of the Alpine drift are thoroughly 

 distinct, distinct enough to make their reference to separate epochs the 

 most natural method of classifying them. 



Later than the three glacial epochs, as determined by Penck and his 

 associates, there are said to be two later sets of moraines in Switzerland. 

 To these Professor Penck assigns a "post-glacial" age. Geikie thinks 

 they may belong to the fourth and fifth epochs, according to his gen- 

 eral classification for the whole of Europe. This would make five gla- 

 cial epochs in Switzerland, according to Geikie, two of which are "post- 

 glacial," according to Penck. 



Evidence of the same general import is likewise found in the 

 Auvergne. It will thus be seen that the evidence for the existence of 

 multiple glacial epochs is not confined to one area, or even to a few 

 closely associated areas. The evidence is drawn from widely separated 

 sources, and is found in all regions which were extensively affected by 

 glaciation. 



Concerning the general question of the division of the glacial 

 period into epochs, it may be said that too much reliance is not to 

 be placed on specific bits of evidence, or on specific lines of evidence. 



