16 ALBRECHT PENCE 



guish between cirques in valleys and cirques on slopes, between 

 trough's ends and corries. 



The forms produced by small glaciers on the slopes of the valleys 

 vary very much. One feature is produced everywhere where the 

 glaciers are overlooked by rocks ; that is, the corrie cliff, originated by 

 sapping. The formation of a basin at the foot of these cliffs depends 

 on the same conditions as the formation of a basin in a valley occu- 

 pied by a glacier; it is only formed where the successive cross-sections, 

 after having increased, again, diminish — a condition which is regu- 

 larly found in those glaciers which end on the slope on which they 

 began. The true corries, with basins in their bottoms, are therefore 

 mostly the beds of isolated hanging glaciers which did not descend 

 far below the snow limit, and their bottoms lie nearly at the level of 

 this limit. But if on the slopes we have glaciers which feed the valley 

 glaciers, then we have usually to deal only with an increase of their 

 cross-sections, and their bottoms descend without interruption some- 

 what below the surface of the valley glaciers. Then an open corrie 

 is formed, the bottom of which often terminates rather abruptly a 

 little below the scoring limit along the sides of the glacier valley. 

 There are many transitions between the true, closed corrie and the 

 open corrie; for there are many transitions between isolated hanging 

 glaciers and affluent hanging glaciers. Now and then we find closed 

 corries along the sides of a valley glacier, formed by its lateral affluents, 

 which were dammed up by it. On the other hand, we find open corries 

 as the beds of local, isolated glaciers, which lay on slopes the steep- 

 ness of which was not favorable to the establishment of reversed 

 slopes. 



Closed corries prevail in the eastern parts of the Alps, where this 

 mountain chain did not reach far above the snow-line of the Great 

 Ice Age. Now and then we find here mountains with a single corrie 

 or Kar, whose steep cliffs contrast strongly with the rounded and 

 smoothed forms prevailing around it. Other summits are rather 

 crowded with corries, which have eaten back so far that there is only 

 a part of the old rounded mountain surface conserved. In other 

 cases the last trace of the latter has disappeared, and there is a sharp 

 crest line which separates the corries or Kar e of opposite sides. If this 

 crest disappears under the attacks of the glaciers, then a flat surface 



