QUATERNARY 



645 



Distribution of the Ice Sheets 



The great event of the Pleistocene was the accumulation of vast 

 continental glaciers. 



1. Other Continents. — As a result of the increasing cold the 

 whole of northern Europe (Fig. 564) was buried under an ice sheet of 

 great thickness, which filled up the basins of the Baltic and North 

 seas and spread over Scotland and the greater part of England. 





Fig. 564. — Map of Europe during glacial times. The area covered by glaciers 

 is shaded, and the direction of the movement of the ice is indicated by arrows. (After 

 J. Geikie.) 



The Alps and Pyrenees were covered by great snow fields and glaciers 

 which stretched over the neighboring lowlands, and even the island 

 of Corsica had glaciers. In the southern hemisphere and in the tropics 

 glaciers appear to have existed where none are now, and our present- 

 day glaciers are insignificant remnants of those of Pleistocene times. 

 One interesting exception to the general glaciation of the northern 

 portion of the Old World was the absence of glaciers in Siberia, where, 

 even at the present, a portion of the country has a mean temperature 

 of five degrees, the soil is permanently frozen to a depth of several 

 hundreds of feet, and Arctic conditions prevail over large areas. 

 The absence of glaciers is now, and probably was then, due to the de- 



