1 88 
SCENERY OF SWITZERLAND. 
CHAPTER VII. 
ACTION OF RIVERS. 
Although the elevation of the Swiss Alps is the 
result of geological causes, the present configuration 
of the surface is mainly due to erosion and denuda- 
tion. It is indeed impossible to understand the 
physical geography of any country without some 
knowledge of the action of water, and especially of 
rivers. 
The velocity of a stream depends partly on the 
inclination of its bed, and partly on the volume of 
Fig. 4 7. — Final Slope of a River. 
water; if then we study an ancient river which has 
passed the stormy period of childhood, and forced 
its way through the obstacles of middle life, so that 
its waters run with approximately equal rapidity, we 
shall find that the slope diminishes from its source to 
the sea or lake into which it falls, with some such 
curve as in Fig. 47. 
