192 



CLIMATE OF EUEOPEAN DRIFT 



[Ch. X. 



vegetation capable of nourishing these great quadrupeds to 

 have once flourished between the latitudes 40° and 65° N". 



Climate of European Drift and Gave Deposits. — We 



m 



ay 

 now ask, with what European deposits does the frozen mud 



of Siberia containing the remains of the mammoth 



m so 



fresh a state correspond geologically ? Their superficial dis- 

 tribution, and the species of mammalia, as well as the fact 

 that the shells which Middendorf and others observed 



m 



them are of living species, seem to connect them chronologi- 

 cally with that paleolithic drift in which flint implements 

 have been detected in England, France, and Italy. The 

 temperature which prevailed in the valleys of the Thames, 

 Somme, and Seine at the era in question, was, according to 

 Mr. Prestwich, 20° Fahrenheit colder than now, or such as 

 would now belong to a country from 10° to 15° of latitude 

 more to the north.* This estimate is founded on a careful 

 analysis of the land and freshwater shells which accompany 

 the remains of the mammoth and its associates in the 

 paleolithic alluvium. If we confine our attention to those 

 terrestrial shells which are most commonly buried in the 

 same gravel and sand as the JElephas primigenius and Rhino- 

 ceros tichorhinus, we find them to amount to no less than 

 48 species in the valley of the Thames and its neighbourhood. 

 All but two of these still survive in Britain ; these two, 

 Helix incamata and Helix ruderata, still inhabit the continent 

 of Europe, and have a great range from north to south. The 

 associated freshwater shells, more than twenty in number, are 

 also British species ; but as they occur, with two or three 

 exceptions, as far north as Finland, their presence is not 

 opposed to the hypothesis of a cold climate, especially as the 

 Limncece are capable of being frozen up, and then reviving 

 again when the river-ice melts. At Fisherton, near Salisbury, 

 one of the rude flint implements of the earliest stone age 

 was found in drift containing the mammoth and Siberian 

 rhinoceros, together with the Greenland lemming and a 



Spermophilus, a northern form of quadruped allied to the 



marmot 



living species ; the whole assemblage being confirmatory of 



* Prestwich, Phil. Trans., 1864, part 2, p. 89. 





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