68 THE WORLD'S LUMBER ROOM. 



The glacier's motion, like that of a river, is greatest on 

 the surface, and greater in the middle than at the sides ; and 

 what with the strain resulting from this unequal motion, and 

 the extremely rough uneven character of its bed, its surface 

 is also rough, and rent with cracks and fissures of all sizes, 

 from a few inches to several feet across. 



Looking down upon it from a height, we should generally 

 see on either side the glacier a dark line, which, on closer 

 examination, would prove to be a mound of fragments, large 

 and small, and huge blocks, many tons in weight, which 

 have fallen from the cliffs and mountains bounding it on 

 either side, and are thus being gradually carried down 

 into the valley. Thousands of tons of rock and rubbish are 

 continually falling from the heights above ; and when two 

 glaciers meet, as not unfrequently happens, the two nearest 

 "moraines," as these rubbish mounds are called, join together 

 and form a central moraine, often twenty or thirty feet 

 high. The three moraines then travel on together to the 

 end of the glacier, where the ice melts and drops them, 

 forming a " terminal moraine," perhaps eighty or 100 feet 

 high. 



But glaciers, like rivers, are " dust-makers," as well as 

 " dust-carriers," for the joints which exist in all rocks, in a 

 greater or less degree, make it easy both for running water 

 and ice to force the blocks out of their places ; and then, 

 besides the immense heaps of rubbish which the glacier 

 carries on its surface, large quantities also fall into its cracks 

 and fissures, and, being jammed in between the ice and its 

 bed, are pressed against the rocks by all the weight of the 

 mass above. These fragments of stone are, in fact, the 



