CH. XL. 



GLACIERS. 



449 



geologist, named De Saussure, spent much time in examining 

 the glaciers of the Alps, and pointed out how they are now- 

 forming large deposits in the valleys out of these heaps of 

 rubbish which they bring down from the mountains. Since 

 his time many geologists had taken up the study, but it was 



FIG. 74. 

 Glacier carrying down Stones and Rubbish (Lyell). 



Professor Agassiz who first spelled out the wonderful history 

 we can learn from it, about the former climate of our hemi- 

 sphere. He noticed that rocks over which a glacier has 

 moved are polished and grooved by the rough stones and 

 sand frozen into the bottom of the ice, just in the same way 

 as a piece of wood is scraped by the sharp iron at the 

 bottom of a plane ; and by these glacial scratches or stria. 



