258 GENERALIZATIONS. 



that these numbers, by their immensity, are just as little com- 

 prehended by the human mind as are the natural phenomena 

 which they should lay open before us. 



Section 2. Action of Water. 



Movements proceeding from the interior of the earth, and 

 modified by the character of the terrestrial crust, have produced 

 those wrinkles of the surface which we call mountains and val- 

 leys. But in their further development water has been a very 

 important agent. When, in summer, we walk over a large 

 glacier, we see not unfrequently on the surface a regular system 

 of little hills and valleys formed by the water flowing over the 

 ice. This gives us a good idea of the process that must take 

 place when a river makes its way down an inclined plane. Its 

 action is denned by the degree of inclination of the surface and 

 the mass of the water. Wherever firm land exists, this action 

 of water will commence, and during all geological periods 

 water has assisted in determining the configuration of Swit- 

 zerland. In the earlier ages of the world, when the sea 

 threw its waves upon the shore, this action influenced the 

 formation of the coast; but the present form of Switzerland is 

 especially due to the waters of the Pliocene and Quaternary 

 periods. 



A glance at the Swiss map shows that the mountain- chains 

 and longitudinal valleys produced by the upheaval of the Alps 

 follow a direction from south-west to north-east. The flow of 

 the waters in this region was determined by the valleys which 

 owe their origin to the upheaval ; and the main rivers, the Rhone 

 and Rhine, have the same direction from Coire to Martigny. 

 From Martigny to the Lake of Geneva transverse valleys cut 

 through the mountains ; and the Rhone, following these gorges, 

 bends nearly at a right angle and flows towards the north-west. 

 The same direction is taken by the Rhine from Coire to Sargans; 

 but there, instead of passing through the great valley-lake 

 of Wallenstadt, the river follows the fissure (cluse) of the 

 Schollberg and flows into the Lake of Constance. Although the 

 direction of these rivers and brooks of the Alpine region is de- 

 termined bv the stratification of the Swiss mountains, the 



