2U THE EARTH MADE READY FOR MAN 



wherever the ice in melting had left them bare. 

 They were smoothed off and almost polished, while 

 deep scratches ran parallel to the direction in which 

 the glaciers were moving. So when he came to this 

 country he knew what those marks meant which 

 had puzzled our learned men. 



Glaciers had made the marks, — glaciers of such 

 extent that they stretched in one mass of ice across 

 the northern part of North America. As high upon 

 the mountain sides as the rocks were ground off, 

 so thick was the ice that had flowed over the land. 

 It had scoured off all the rocks on its way toward 

 the south, and carved them with straight lines and 

 grooves. 



What do you suppose were nature's carving 

 tools? They were the pieces of rock that had been 

 broken off the ledges as the mighty glacier pushed 

 its way irresistibly over the land. Frozen into the' 

 mass, they were held as tight as in a vise. Thus they 

 traveled with the moving ice, scraping the rocks 

 smooth while the harder, sharper fragments scratched 

 parallel Hues on the surfaces that had been already 

 bared and smoothed. Such records do the glaciers 

 leave now upon the rocks in the Alps, in Green- 

 land and in Alaska. Such records the glaciers have 

 left upon the rocks in the northern part of North 

 America and Europe. 



Nature has many other ways of telling us about 

 the "Great Ice Age" besides the telltale lines and 

 the smooth rocks. She tells us by the changed 

 shapes of the mountains, by the filled-up valleys, 

 by long, even ridges and rounded hills, and by the 



