45 



T_^-^-r, ._; 



22. — The e>ge of a part of the great Greenland ice sheet 

 {on the left) resting on the land, over which art strewn 

 many houldera brougltt hy the ice and left there when it 

 melted. 



This vast ice sheet is slowly iiK.ving outward in all directions from 

 the elevated center, much as a pile of wax may be made to tlow 

 outward by plac- 

 ing a heavy weight 

 upon the middle. 

 Moving toward 

 the north, east, 

 south and west, 

 this glacier must 

 of course come 

 to an end some- 

 where. In places, 

 usually at the heads 

 of bays, the end is 

 in the sea, as the 

 end of our glacier 

 must have been off 

 the shores of New England. From these sea-ends, icebergs con- 

 stantly break off; and, floating away toward the south, often reach, 



before they melt, as far as the 

 path followed by the steamers 

 from the United States * to 

 Europe. Between the bays, 

 where the glacier ends in the sea, 

 the ice front rests on the land 

 (Fig. 22), as it did over the 

 greater part of New York and 

 the States further west. There 

 it melts in the summer, supply- 

 ing streams with water and fill- 

 ing many small ponds and lakes. 

 The front stands there year after 

 year, sometimes moving a little 

 ahead, again melting further 

 back so as to reveal the rocks on 

 33. — A scratched pebble taken from the which it formerly rested. 



ice of the Greenland glacier. Examining tills rock it is 



found to be polished, scratched and grooved just like the bed-rock 

 in New York ; and the scratches extend in the direction from which 



487 



