372 



THE WORK OF RUNNING WATER 



waterfalls furnish power for 

 mills, factories, electric rail- 

 ways and lighting, and in- 

 dustries spring up and the 

 inhabitants become indus- 

 trial rather than agricultural. 

 In the old valleys, the slopes 

 are gentle and the floor broad 

 and fertile and adapted to 

 farming; water power is low 

 and too meager for 

 facture, and agriculture 

 the principal means of liveli- 

 hood. Navigation is difficult 

 and even dangerous in the 

 younger valleys, transporta- 

 tion is limited to railroads, 

 and commerce is retarded by 

 lack of outlets to markets. Navigation in older rivers is easy, 

 transportation is cheap, and a natural outlet to the commercial 



FIG. 240. A waterfall. 



manu- 



is 





m 



FIG. 241. Waves beat unceasingly against the shore. 



