14 ALBRECHT PENCE 



terminal moraines in the valleys, where they separate the reversed 

 drainage in the region of diffluence from a peripheral drainage. 

 The latter has been partially formed by shoving away the original 

 rivers which descended to the ground before it was entered by the 

 glaciers. When the ice came, they could not continue their courses 

 and must flow along its rim. Thus they were pushed from their 

 old courses and driven into new ones, which surround the ends of 

 the glaciers. Many of these shoved river courses are no longer in 

 use, having often been captured by the headwaters of the reversed 

 drainage, as, for example, the Mangfall in Bavaria, which for a long 

 distance flows along the terminal moraines of the Inn glacier, until it 

 makes an elbow at the place where it was captured by a stream flowing 

 on a reversed slope. Other shoved river courses became stable, 

 since they were driven into the valleys of other rivers. Thus north of 

 the old glacier of the Dran the waters of the upper valley of the Gurk 

 were shoved by the rim of the ice into that valley which is now that 

 of the middle Gurk, and which formerly had its own river. Here 

 the moraine of the glacier along which the Gurk was shoved is still 

 visible. In other cases the moraines are insignificant, especially 

 where the glacier ended in a deep valley, and the course of shoved 

 rivers can be traced only by the erosive action exercised along the 

 glacier, cutting gorges into the projecting parts of the valley side. A 

 magnificent example of such a shoved river can be followed on the 

 left slope of the valley of the Sesia in upper Italy below Varallo. By 

 their erosion on mountain passes, by establishing reversed slopes in 

 their terminal regions, and by shoving the rivers coming from non- 

 glaciated regions, the old glaciers of the Alps have profoundly 

 modified, especially near their ends, the preglacial hydrography of 

 the Alps. 



The traces of glacial action in the Alpine valleys extend beyond 

 the limits of the trough. Near the ends of the ancient glaciers the 

 troughs are overlooked by moraines, which now and then are located 

 directly on the shoulders. In the interior of the mountains the stri- 

 ated and rounded surfaces reach far above the shoulders, and there 

 is a very marked scoring limit which separates those parts of the valley 

 slopes which have been buried under the ice and rounded by it, from 

 the higher, ragged slopes, which suffered by weathering. The 



