LAKES 



173 



material in its water, the Caspian Sea about 13 per cent, 

 and the Dead Sea about 25 per cent. An effort to swim 

 in these waters gives one an exceedingly queer sensation. 

 The buoyancy is so great that a large part of the body is 

 out of water, and one finds oneself bobbing around like a 

 cork. When boats pass from the fresh water of the Volga 



MINING SALT IN THE DRIED UP SALTON LAKE, CALIFORNIA 



River to the salt water of the Caspian Sea, their hulls grad- 

 ually rise perceptibly higher. 



Where bodies of water like these have dried up, their old 

 beds are exposed as almost level plains. These become 

 exceedingly fertile under irrigation as soon as the salts are 

 dissolved and drained out of the soil. Fine examples of this 

 are the fruitful plains near Salt Lake City and in Imperial 

 Valley, California. 



