PRESENT CHANGES IN THE EAKTH. 105 



that feeds it above would increase from year to year. 

 The rate of flow varies from varying circumstances. 

 Professor Hughes built a house on a glacier, and he 

 found it to move during fifteen years at the average rate 

 of eight inches daily, or over three quarters of a mile 

 during the whole time. A glacier is made out of snow 

 which becomes consolidated into ice, partly by pressure 

 and partly by the infiltration of water, which, by freez- 

 ing, unites all the grains of snow together. In Fig. 40 

 (p. 106) is represented one of the grand glaciers of the 

 Swiss Alps, the glacier of the Viesch. A glacier carries 

 along whatever of loose material it finds in its course, 

 and therefore there is always a row of loose stones, of 

 various size, lying along upon the ice on each side of the 

 glacier. These are called the lateral moraines. In the 

 glacier of the Viesch there is, as you see, a row of stones 

 along the middle. This, which is called a medial mo- 

 raine, arises from the union of two glaciers in one, as 

 two rivers of water unite. In this case the two lateral 

 moraines of the glaciers which are adjacent to each other 

 unite at the confluence. 



189. Termination of a Glacier. The colder is the cli- 

 mate the farther down does the glacier extend. The 

 termination is higher up in the summer than in the win- 

 ter, and it varies in different seasons, according to the 

 temperature of the season. The locality of the end varies 

 sometimes even miles in the course of a series of years. 

 The glacier is sometimes spoken of as retreating, but this 

 language is, of course, not strictly correct, for there can 

 be no movement backward. The apparent retreat is 

 owing to the melting of the lower part of the glacier to 

 a higher point than before. Toward the termination of 

 a glacier the moraines become less and less distinct from 

 the melting of the ice, and at the very end there issues a 

 stream of water, carrying along with it, to a greater or 

 less distance, much of the loose material which the gla- 

 cier has brought down from the rocks. The stream 



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