IRfvers an& ffloofcs* 153 



upon the earth only to go through the same 

 operation again. The whole surface of the 

 earth is divided into drainage areas that lead 

 either directly through rivulets and rivers to 

 the ocean, or into some land-locked basin, 

 where it either finds an outlet under ground or 

 is kept within bounds through the process of 

 evaporation, the same as is the case with our 

 great oceans. In North America the amount 

 of drainage area that has no outlet to the 

 ocean amounts to about 3 per cent, of the whole 

 surface. In other countries the percentage of 

 inland drainage is much larger. The great 

 Salt Lake in Utah is an instance where there 

 is no outlet for the water except through the 

 medium of evaporation. Inasmuch as all 

 rivers and streams contain a certain propor- 

 tion of salt, especially in such strongly alka- 

 line land regions as the Great Basin of the 

 North American continent, these inland 

 lakes in time become saturated with this and 

 other mineral substances. 



Salt is constantly being carried into the 

 lake by the water of the stream that feeds it, 

 and the water is continually being evaporated, 

 leaving the salt behind. This process has 

 been going on in the valley of Utah for so long 

 a period that 17 per cent, of the contents of the 

 lake is salt. The Humboldt Eiver in Nevada, 

 which empties into a small lake of the same 

 name, and lies at the foot of the Humboldt 



