256 THE STORY OF THE EARTH AND MAN. 



represented in Britain; and scarcely at all in north- 

 eastern America; and hence has not impressed the 

 imagination of the English race so strongly as its 

 importance justifies. 



The next succeeding period, that of the Pliocene, 



! continues the conditions of the last, but with signs 

 of decadence. Many of the old gigantic pachyderms 

 have disappeared ; and in their stead some familiar 

 modern genera were introduced. The Pliocene was 

 terminated by the cold or glacial period, in which a 

 remarkable lowering of temperature occurred over all 

 the northern hemisphere, accompanied, at least in a 

 portion of the time, by a very general and great 

 subsidence, which laid all the lower parts of our 

 continents under water. This terminated much of 

 the life of the Pliocene, and replaced it with boreal 

 and Arctic forms, some of them, like the great hairy 

 Siberian mammoth and the woolly rhinoceros, fit 

 successors of the gigantic Miocene fauna. How it 

 happened that such creatures were continued during 

 the Post-pliocene cold, we cannot understand till we 

 have the Tertiary vegetation before us. It must 

 suffice now to say, that as the temperature was 

 modified, and the land rose, and the Modern period 

 was inaugurated, these animals passed away, and 

 those of the present time remained. 



Perhaps the most remarkable fact connected with 

 this change, is that stated by Pictet, that all the 



, modern European mammals are direct descendants 

 of Post-pliocene species; but that in the Post-plio- 



