POTASH SALTS AND OTHER SALINES IN THE GREAT BASIN REGION. 59 



extremely difficult to locate these beds. Until proved otherwise by a number of 

 bores, Railroad Valley must be looked upon as a possible source of buried salines. 

 The question as to whether these salines will be characterized by a high potassium 

 content is an open one. The finding of surface crusts and brines of relatively high 

 potassium content proves nothing as far as we know at present about the buried salines 

 and brines. A possible explanation of the high potassium content in the surface salines 

 and brines may be found in the fact that there are a number of hot springs in this 

 area, and these may have been responsible for the surface salines. Until analyses of 

 the waters of these springs are available this is only conjecture. 



SAND SPRINGS FLAT. 



Sand Springs Flat areais described on the United States Topographic Sheet as "Eight- 

 mile Flat" and "Fourmile Flat." It was called "Alkali Valley" in Russell's Mono- 

 graph on Lahontan Lake. It lies 11 miles southeast of Fallon, in Churchill County, 

 Nev. The area is about 37 square miles. It has a peculiar interest in that a bay of 

 Lake Lahontan once occupied the area. The highest level of Lake Lahontan was 439 

 feet above the present flat, elevation 3,961. The desiccation of Lake Lahontan would 

 have left a shallow lake upon the flat, and this, on evaporation, would have left a bed 

 of salines. Russell states that the salt bed is from 3 to 5 inches thick near the margin 

 and in the central portion is not less than 3 feet thick. Rain water has collected the 

 ealines in the southeast end of the flat. Russell ^ states that after rains a shallow 

 brine lake of several inches depth and about 15 square miles in area occupies this 

 portion. No notable amounts of potassium have been reported from the salines of 

 this area. 



SEVIER LAKE. 



Sevier Lake is in west-central Utah, Millard County. It is of some interest in that 

 it was formerly a part of Lake Bonneville and for a long time was occupied by a shallow 

 lake, which in recent times has dried up. Gilbert ^ describes the history of this lake. 

 From his account I take the following: 



Sections of the saline beds in the central and marginal portions of the dried lake. 



Central. 



Marginal. 



1. Top. Sodium sulphate, 2 inches 



2. Solium sulphate with some sodium chloride, 1 

 inch. 



3. Sodium sulphate, 2 inches 



4. Gray clay containing woody fiber, 2 inches 



6. Fine sand contauiing fresh water shells, 6 

 inches. 



6. Gray clay. 



1. Top. Sodium chloride cnist, J inch. 



2. Sodium chloride with sodium sulphate and mag- 

 nesium sulphate — free crystals mingled with water, 

 IJ inch. 



3. Sodium sulphate with sodium chloride, a crust of 

 coherent crystals, J inch. 



4. Sodium chloride with sodium sulphate; incoherent 

 crystals mingled with water, li inches. 



5. Sodium chloride, with sodium sulphate, chemically 

 identical with No. 2, but fine-grained and with the 

 consistence of an ooze; color white above, with oc- 

 casional passages of pink and green beneath, J inch. 



6. Dark-gray mud, 2 feet. 



The analyses upon these from the same reference are given in the succeeding table: 



Constituent. 



Center. 



Margin. 



Brine. 





Per cent. 

 84.6 

 .4 

 7.0 



Per cent. 

 14.3 



Per cent. 

 15.5 



Sodium carbonate . . 





Sodium chloride 



80.62 



it^ 



72.1 





.5 



Magnesium sulphate . . . . . . 





5.5 









11.9 



Potassium sulphate 





.7 



3.6 



.1 





"Water 





















100.00 



100.00 



100.00 



1 Monograph No. 11, U. S. Geol. .Survey, p. 236. 2 Monograph No. 1, TJ. S. Geol. Survey, p. 244. 



