REVIEWS. 737 



from cold to temperate and back again to cold. The mammalian 

 remains likewise indicate fluctuations of climate. In Central Russia 

 there are fossil beds overlying the drift of the most extensive ice sheet. 

 These fossil beds are not buried by till, since they are beyond the limit 

 of the later advance of the ice, but they are clearly neither post- nor pre- 

 glacial. Thev are thought to represent a climate more humid and 

 more mild than that which now exists in the same region. 



Evidence for the existence of multiple ice epochs is not confined to 

 the fossil beds, strong as their testimony is. In Germany there is an 

 "upper" bowlder clay different in physical and lithological constitution 

 from the "lower." This implies a difference indirection of movement 

 of the ice which formed the two beds of till. Thus in Western Ger- 

 many, the "lower " till was deposited by ice moving from north to 

 south, while the " upper" till was deposited by ice moving from north of 

 east to south of west. This two-fold division of the bowlder clay exists 

 south of the region of the great Baltic ridge, though the southern limit 

 of the "upper" till south of this ridge seems not to have been accu- 

 rately determined. 



As in Britain, so on the continent, Professor Geikie. finds evidence 

 that the ice-sheet which reached farthest south, and which deposited 

 the "lower" till of Western Germany, is not the oldest ice-sheet which 

 affected Northern Europe. In Southern Sweden there is a till or ground 

 moraine older than that produced by the most extensive ice-sheet. 

 This oldest bed of drift, so it is affirmed, was deposited by ice moving 

 from the southeast to the northwest. The overlying drift is the product 

 of ice which moved from north-northeast to south-southwest, or nearly 

 at rignt angles to the direction of the first movement. No interglacial 

 beds are found here, but the diversity of movement is so great that, 

 taken in connection with the extraordinary direction of the first, its 

 significance cannot be trifling. It is to be noted that the foregoing 

 interpretation does not involve three periods of drift deposition in 

 Southern Sweden. The " lowest " ground moraine is referred to the 

 first epoch (the time equivalent of the Weybourn crag), while the 

 "upper" must be made to include the deposits of the second and third, 

 if deposits of both exist. Some corroborative evidence of a great 

 " Baltic " glacier, which antedated the most extensive mer de glace of the 

 continent and of Britain, is thought to be found in certain fossil beds 

 of Central Germany, though for their own particular region these fos- 

 sil beds are thought to be pre-glacial. The " lower " till of Central Ger- 



