REVIEWS. 93 



believed to have become again continental, while the climate became 

 so far ameliorated as to allow the growth of great forests. Subse- 

 quently the insulation of Britain was effected, and this was followed 

 by a climate which was probably colder than the present. 



5. The severity of the climate which marked the close of the 

 fourth interglacial interval was such as to bring about local glaciation 

 in some of the mountain valleys of Britain. Here and there the 

 glaciers projected their moraines so far down the mountains that they 

 rest on what is now the 45 to 50 feet beach. In the Alps, this fifth 

 epoch of glaciation is represented by the so-called postglacial moraines 

 in the upper valleys. This is believed to have been the last appearance 

 of glaciers in Britain. The dissolution of these glaciers was again 

 followed by an emergence of the island, and by more genial climatic 

 conditions. 



In support of his conclusions. Prof. Geikie cites some striking 

 facts which are not so widely known as they should be. For example, 

 Swedish geologists have found evidences that there was an ice sheet 

 antedating that which deposited the "lower diluvium," and that during 

 this earlier glaciation the direction of ice movement in southern 

 Sweden was from the south-east to the north-west. The ground 

 moraine deposited by this ice sheet is overlain by the "lower diluvium" 

 which was produced by an ice movement from the north north-east to 

 the south south-west, or nearly at right angles to the first. Again, near 

 Moscow, there exist interglacial beds whose plant remains indicate a 

 climate milder and more humid than that of the present time. These 

 interglacial beds, it will be observed, occur in the region of the 

 "lower diluvium" quite beyond the margin of the ice which produced 

 the " upper diluvium " of Germany and Scandinavia. During this inter- 

 glacial interval, Prof. Geikie maintains that no part of Russia could 

 have been covered with ice. If, then, within the limits of the area 

 covered by the "lower diluvium," and not by the "upper," distinct 

 beds of glacial drift are separated by such beds as those cited, there 

 can be no question but that such separation marks two distinct glacial 

 epochs. If there was an earlier glaciation when the movement of the 

 ice in Sweden was at right angles to that during which the lower part 

 of the " lower diluvium " was produced, this also would seem to be good 

 evidence of three ice epochs prior to the "upper diluvium." The epoch 

 of the "upper diluvium" would then constitute the fourth glacial epoch, 

 and this is the interpretation of Prof. Geikie. 



