44 



Virginia, to live in Greenland, now ice covered. When the ice of 

 the glacier melted away it left only signs of its presence ; but when 

 the temperate latitude plants grew in Greenland they left seeds, 



leaves and tree 

 t r u n k s which 

 have been im- 

 bedded in the 

 rocks as fossils. 

 One may now 

 pick the leaves of 

 temperate cli- 

 mate trees from 

 the rocks be- 

 neath a great 

 icecap. 



N e V ertheless, 

 to one who stu- 

 dies them, the 

 signs left by the 

 glacier are as 



clear proof as the leaves and seeds. From these signs we know that 

 the climate has changed slowly, but we have not yet learned why it 

 changed. 



There are now two places on the earth where vast glaciers, or ice 

 sheets, cover immense areas of land, one in the Antarctic, a region 

 very little known, the other in Greenland, where there is an ice 

 sheet covering land having an area more than ten times that of the 

 State of New York. Let us go to this region to see what is being 

 done there, in order to compare it with what has been done in New 

 York. 



In the interior is a vast plateau of ice, in places over 10,000 feet 

 high, a great icy desert (Fig. 21), where absolutely no life of any 

 kind, either animal or plant, can exist and where it never rains, but 

 where even in the middle of summer the storms bring snow. Such 

 must have been the condition in northeastern America during the 

 glacial period. 



436 



21. — A view over the great ice plateau of Greenland with 

 a mountain peak projecting above it. 



