AQUEOUS AGENCIES. 81 



w;iy with silt, until filially only a mother liquor is 

 left, which is very difficult to dry away. 



Now, all these stages are actually found in Nature. 

 Great Salt Lake has reached the saturation point, and is 

 beginning to deposit. The Dead Sea has deposited largely, 

 and its composition is that of a half exhausted mother 

 liquor. Lake Elton, on the Russian steppes, has deposited 

 all its salt, and its composition is that of a wholly exhausted 

 mother liquor. Borings about the shores of Lake Elton 

 show an alternation of silt and salt many times repeated, 

 such as we have described. The bearing of these facts 

 on the explanation of what are called salt-measures will 

 be seen when we come to treat of these. 



In cases of saline lakes formed by the accumulation of 

 the waters of rivers and springs, the deposits are far more 

 complicated. The deposits found in the dried-up lakes 



FIG. 42. An island of tufa in Pyramid Lake, Nevada. 



of Nevada consist of common salt, lime carbonate, soda 

 sulphate, soda carbonate, soda borate (borax), and soda 

 lime borate (ulexite). 



LK CONTE, GEOL. 6 



