CHAP, v.] EVIDENCE AS TO CLIMATE. 113 



trated, comprising the region north of a line passing from 

 Yorkshire eastwards through Hamburg and Eussia ; 2d, 

 the middle zone, common to both groups of animals, 

 extending south of this line as far as the Pyrenees, the 

 Alps, and Hungary ; and lastly, the southern, into which 

 the northern animals never penetrated, or Spain, Italy, 

 and Greece. It must further be observed that the range 

 of the mountainous species, such as the ibex, into the 

 region of the southern animals into the Apennines, the 

 Sierra Nevada the Atlas, and the mountains of Sardinia, 

 of Crete, and Anatolia, shows that the distribution of 

 the Pleistocene mammalia was regulated by climate rather 

 than by physical barriers. 



From this distribution we may infer that the 

 climate was severe in the north and warm in the south, 

 while in the middle zone, comprising France, Germany, 

 and the greater part of Britain, the winters were 

 cold, and the summers warm as in middle Asia and 

 North America, where large tracts of land extend 

 from the Polar region towards the equator, and offer 

 no barrier to the swinging to and fro of the animals. 

 In the summer time the southern species would pass 

 northwards, and in the winter time the northern would 

 swing southwards, and thus occupy at different times of 

 the year the same tract of ground, as is now the case 

 with the elks and reindeer. 



It must not, however, be supposed that the southern 

 animals migrated from the Mediterranean area as far 

 north as Yorkshire in the same year, or the northern as far 

 south as the Mediterranean. There were, as we shall see 

 presently, secular changes of climate in Pleistocene Europe, 

 and while the cold was at its maximum the arctic animals 

 arrived at the southern limit, and while it was at its 



I 



