62 EARLY MAN IN BRITAIN. [CHAP. in. 



streams of lava and clouds of ashes. In Switzerland 

 also the formation of great lakes of upper Meiocene age 

 was accompanied by the development of volcanoes, at 

 Oeningen. 1 



The central axis of the Alpine chain occupied its 

 present position, and may have been as high or higher 

 than it now is. The denudation, by which it has 

 suffered in the long lapse of ages since the Meiocene 

 times, has been compensated by the amount of elevation 

 by which the Meiocene strata of the Tongrian zone 

 have been lifted up no less than 10,940 feet above the 

 sea in the Dent du Midi. Those of the Helvetian zone 

 have been elevated 2470 feet at Lausanne, and 2800 at 

 Berne. 2 



The same remarks apply also to the Pyrenees, although 

 their history has not been made out with the same 

 accuracy as that of the Alpine chain. 



The Meiocene Climate. 



The testimony as to climate offered by the Meiocene 

 vegetation is clear and decisive. The numerous palms 

 could only have flourished under a warm and equable 

 climate, and the flora as a whole is now only to be 

 found in sub -tropical regions, where the winters are 

 very mild. In the vast lapse of time, however, repre- 

 sented by the Meiocene strata in Switzerland, a gradual 

 lowering of temperature is marked by changes in the 

 vegetation. In the lower Meiocene, or Aquitanian stage, 

 evergreen trees and shrubs constitute nearly three- 

 quarters of the whole forest, while in the upper Meiocene 



1 IJeer, Primeval World of Switzerland, i. p. 303. 

 2 User, op. cit. 



