2 ALBRECI1T PENCE 



valleys are usually not accordant; they do not lie at the level of the 

 main valley, but at a higher level; their rivers often tumble down in 

 waterfalls to join the master-river, or they have cut into the floor 

 of the lateral valleys a deep gorge, through which they whirl, and rush 

 to reach the bottom of the main valley. These are the very well- 

 known Klammen of the eastern, and the "gorges" of the western, 

 Alps; and many waterfalls of this mountain chain lie at the mouths of 

 the side valleys. 



The cross-sections of our Alpine valleys are also other than what 

 one might expect. The master- valleys have in general an extended 

 flat bottom, at the sides of which rise very steep walls. At a certain 

 height, steep slopes below change into more gentle ones above. Well- 

 marked ledges separates the two slopes, and form distinct shoulders 

 on both sides of the valleys — a condition not usually found elsewhere. 

 That part of the valley which lies below the shoulders has often a 

 trough-like appearance. The trough extends upward to that region in 

 which the aggraded valley bottom is succeeded by a series of descend- 

 ing rocky steps, and here is often formed a very striking trough's 

 end, by the cliff side of a high step. Above the shoulders the valley 

 slopes are far from being regular; often they form cirque-like niches, 

 at the bottoms of which little tarns occur. These are the Kar of the 

 Alps, the "corries" of Scotland. 



There are certain rules which control the occurrence of all these 

 features. The heights at which the side valleys terminate above 

 the main valley show a pretty regular arrangement. They describe 

 a curve which slopes down regularly between the height above the 

 trough end and that point where we meet with the last part of the 

 reversed slope of the valley floor. The shoulders show a similar, 

 but less regular, arrangement; they are also limited by the trough's 

 end and the end of the last reversed slope of the valley floor; their 

 height also decreases, though not regularly, between these two points. 

 The whole arrangement leads to the conclusion that the trough has 

 been excavated in an older valley with a higher floor; the shoulders 

 are the intersections between the trough sides and the side slopes of 

 the old valley. The hanging side valleys are parts of the old valley 

 system which suffered little from erosion, and conserved their original 

 depth. This condition is now generally accepted, since the connection 



