STORY A SCRATCHED ROCK TELLS 245 



great stretches of land covered with gravel and sand 

 and boulders. These the great ice sheet left scat- 

 tered about over the ground when it finally melted 

 and retreated toward the north. 



Although nothing upon the earth's surface could 

 stop a great glacier, the sun's rays could. So, when 

 the climate became warmer, the vast ice sheet melted 

 into rivers of water and gradually shrank away 

 until now only a few mountain glaciers, those of the 

 Alps and Rockies, and those in the polar regions, 

 are left. 



In Switzerland rivers of water come pouring out 

 of the end of the melting glacier. So in our country 

 long ago rivers must have poured out all along the 

 southern margin of the ice-sheet as it gradually 

 melted away. Here and there vast beds of gravel 

 and sand were spread out by these gushing waters; 

 here and there huge boulders that had been carried 

 under, in, or upon the ice were dropped and left, 

 sometimes piled up in strange confusion. 



When at last our country was free from its ice 

 chains, and the rushing waters that had carried the 

 melting ice to the sea had finally subsided, what a 

 changed surface was laid bare! The sharp peaks of 

 the mountains had been rounded over, and smooth, 

 round hills of clay were scattered about where no 

 hills had been before. Plateaus of sand stood high 

 above the level plains. Long even ridges of gravel 

 stretched along like artificial embankments, while 

 thick sheets of gravel were spread over great tracts of 

 land, often blocking up the river channels and dam- 

 ming back the rushing water into beautiful lakes. 



