234 GEOLOGICAL HISTORY OF LAKE LAHONTAN. 



orates, are known as "vats." These are arranged alternately and may be 

 multiplied to any extent. A profile through a reservoir and the vats on 

 either hand is shovpn in the diagram. 



Vat. Reservoir. Vai. 



Fig. 30. — Section of rt^servoir and vats at Eagle Salt Works, Nevada, 



The lake deposit here is a fine greenish mud or clay, and is so com- 

 pleteh' saturated with brine that a thick crust is formed on the surface by 

 efflorescence every dry season. The salt, being supplied from the beds be- 

 low the surface, is renew^ed every summer, thus allowing a series of crops 

 to be gathered from the same ground. 



A sample of brine from a vat in which the salt had begun to cr3^stallize 

 was analyzed by Mr. Taylor, with the following result : 



Specific gravity, 1. 2115. 



Silica (insoluble.) 0028 



Irou ami aliiiiuna (insoluble) 0004 



Calcium sulphate 2897 



Calcium chloride 3578 



Maguesium chloride 3787 



Potassium chloride 0023 



Sodium chloride 25.3793 



Water 73.5890 



100. 0000 



The annual yield of salt during the past ten years is reported to have 

 been about 2,500 tons. The production has been determined solely by the 

 demand. The amount that could be collected by the simple process of leach- 

 ing the saline lake-beds and evaporating the saturated waters is practically 

 without limit. 



SAND SPRING SALT WORKS. 



The most instructive salt field in the Lahontan basin is situated at the 

 eastern end of a long, barren valley, joined to the Carson desert on the 

 southeast by a narrow pass, and known as Alkali Valley. The floor of this 

 valley, when left dry by tlie evaporation of Lake Lahontan, had the same 

 general level as the Carson desert, and tlie lake-beds may be traced through 

 tlie });iss from one desert to tin; other. In riding from the Carson desert 

 ea.stw;u(l into Alkali Valley, one comes to a line crossing Alkali Valley from 



