e gptW of 



tion to the material which the glacier gathered 

 up and excavated, it also carried the wreckage 

 brought down by landslides and the eroded 

 matter poured upon it by streams from the 

 heights. Most of the material which falls upon 

 the top of the upper end of the glacier ulti- 

 mately works its way to the bottom, where, 

 with the other gathered material, it is pressed 

 against the bottom and sides and used as a cut- 

 ting or grinding tool until worn to a powder or 

 pebbles. 



Train-loads of debris often accumulate upon 

 the top of the glacier. On the lower course this 

 often is a hundred feet or more above the sur- 

 face, and as the glacier descends and shrivels, 

 enormous quantities of this rocky debris fall off 

 the sides and, in places, form enormous embank- 

 ments; these often closely parallel long stretches 

 of the glacier like river levees. 



The large remainder of the material is carried 

 to the end of the glacier, where the melting ice 

 unloads and releases it. This accumulation, 

 which corresponds to the delta of a river, is the 

 terminal moraine. For years the bulk of the ice 



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