GLACIAL FEATURES OF THE ALPS 15 



chamfer at the scoring limit (Schliffkehle) exhibits clearly a sapping 

 action of the ice exercised along its sides, and this lateral erosion seems 

 to have been strongest near the surface of the glacier. This condi- 

 tion is perhaps caused by the more brittle state of the glacier ice near 

 its surface, while the trough indicates that the glaciers eroded inten- 

 sively downward at their bottoms. 



Glaciers not only exercise a sapping action along their sides, but 

 also at their very heads, if they are here overlooked by rock cliffs. 

 There is always a marginal crevasse, called in German Randspalte 

 or Bergschrund, which separates the moving ice from the rocks 

 which overlook it. The material loosened here by weathering falls 

 down from the rock walls into this crevasse and arrives at the bottom 

 of the neve, where it is pushed forward by the moving mass grind- 

 ing the bottom of the glacier. By this, not only the formation of 

 screes around the glacier is hindered, but also the .surrounding cliffs 

 are constantly attacked, for the erosive action begins just at their 

 foot and saps them. Glaciers, therefore, which are formed on 

 slopes in broadly open valley basins, surround themselves finally 

 by cliffs, which are pushed backward much as are the cliffs around 

 the gathering basin of a torrent. The bottoms of hanging glaciers 

 may be transformd much as are the floors of main valleys which are 

 occupied by glaciers. The rule of the cross-sections is equally appli- 

 cable to them. A glacier, for example, which ends on the slope can 

 erode the central parts of its bed below the level of its lower end and 

 thereby establish reversed slopes. Thus the original broadly opened 

 valley basin will be gradually changed into a sharply limited niche 

 with a basin on its bottom. The cirquelike form originating in 

 this way is the Kar or "corrie." It differs essentially from that 

 cirque which forms the end of a valley trough, though there is often 

 much similarity in their mere appearance. The trough's end is 

 formed in the bed of a glacier; the corrie at the head of the glacier. 

 The ice moves down over the cliffs of a trough's end, while it moves 

 away from the cliff of a corrie. After having climbed over the 

 walls of the trough's end, one arrives at a flat, formerly occupied 

 by a hanging glacier usually surrounded by cliffs. Then one arrives 

 at a corrie or a series of corries. An ascent of the walls of a corrie 

 always leads one to the crest of mountains. Therefore we distin- 



