50 



BULLETIN 61, U. S. DEPARTMENT OF AGRICULTURE. 



the marginal portions silt deposits -would be greatest, and the salines deposited here 

 would be characterized by a large proportion of insoluble material. In a single large 

 basin the lake during evaporation might be divided into several smaller lakes, and 

 each would have its individual conditions and in each case would form saline deposits 

 differing from the others. Lastly, the nature of the salines would be expected to differ 

 in different lake basins. The proportions between chlorides, sulphates, carbonates, 



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I 



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f<C/ 



Mf2 C03 



WiiiillllPl.^ 



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rA/o/^Co^ 



Mr^So^ 



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40 50 60 



FiG. 6.— Order of deposition of salts in Owens Lake and Mono Lake. 



bicarbonates, and the basic ions present would vary somewhat from the two samples 

 chosen for establishing our criteria. 



Another condition requires discussion. Salines are deposited upon and in lake bot- 

 toms. The lake sediments would include saline waters and, as desiccation proceeded, 

 the lake sediments would include waters containing gradually increasing amounts 

 of saline material. When saturation is reached not only would brine be expected but 

 individual crystals of the different salts would also be so included. If crystallization 



}>roceeded faster than sedimentation, the lake sediments would contain larger and 

 arger proportions of saline material. If sedimentation proceeded faster than crys- 

 tallization, smaller proportions of saline material would be expected. It is evident 



