78 DYNAMICAL GEOLOGY. 



Conditions of the Formation of Saline Lakes. 



Any lake will, in time, become saline if it has no outlet ; 

 but whether or not it has an outlet depends on the relation 

 of supply by rivers and springs to waste by evaporation. 

 If the supply exceeds the waste, the lake will rise until it 

 finds an outlet, and remain fresh i. e., the quantity of 

 saline matter is so small as to be imperceptible to the 

 taste. But if the waste be equal to or exceed the supply, 

 so that the quantity of water is stationary or diminishes, 

 then the salting process begins. Every drop of river or 

 spring water coming into the lake contains some saline 

 matter, however small, gathered from rocks and soils, 

 and this is, of course, left in the lake. Thus there is a 

 continual leaching of all the surrounding soils, and an 

 accumulation of the leachings in the lake. It may take 

 thousands or even hundreds of thousands of years, but in 

 time the lake will become saline, and more and more so, 

 until finally the point of saturation is reached and deposit 

 begins. 



I have taken the case of concentration of river water, 

 but it matters not how the lake was originally formed ; 

 the same conditions will determine its saltness or fresh- 

 ness. For example, if a salt lake be formed by the isola- 

 tion of a portion of sea water in the gradual upheaval of 

 a continent, whether it remains a salt lake or whether it 

 becomes fresh will depend on the conditions indicated 

 above. If, for example, the sea bottom and contiguous 

 land about the Golden Gate were elevated so as to sepa- 

 rate the Bay of San Francisco from the Pacific Ocean, 

 this bay would certainly become a fresh lake ; for the 

 amount of water coming into the bay is far greater than 

 the waste by evaporation. This is shown by the fact 

 that, although so fully connected with the ocean, the 

 waters of the bay are far fresher than those of the sea. 

 The water of the bay would therefore rise until it found 

 an outlet to the sea, and then would commence a process 



