46 THE OCEAN 



there are numerous inland drainage areas 

 in most of which are lakes. In these areas the 

 precipitation of rain on the whole catchment 

 basin is less than the evaporation ; conse- 

 quently there is no outflow from such a basin 

 into the ocean. The higher lakes in a drainage 

 area of this kind have an outflow into the 

 lowest one and are fresh to the taste, like 

 river-water, but the terminal lake is salt to 

 the taste, like sea-water. The valley of the 

 Jordan with the fresh-water Lake of Tiberias 

 and the salt Dead Sea is an example. The 

 greater part of the " run-off " from the land 

 in the catchment basin of the Jordan ulti- 

 mately finds its way into the Dead Sea, which 

 may be compared to a huge evaporating basin ; 

 the surface layer of water is removed by 

 evaporation under the action of winds and the 

 sun's rays, the salts in solution being left be- 

 hind. In this way in the course of time the 

 Dead Sea has attained its great salinity. The 

 concentration in a salt lake may go on till the 

 lake completely dries up and only saline 

 deposits are left behind. 



In a similar manner the run-off from the 

 whole of the land-surfaces of the globe carries 

 dissolved salts into the ocean, but whereas 

 the composition of the water in salt lakes is 

 determined by the geological structure and 

 climatic conditions of a comparatively small 



