136 CLASSIFICATION OP THE PUBLIC LANDS. 



potash salts. As a whole, the quantity of potash associated with the 

 sodium and other bases is so small — only 2 or 3 per cent of the 

 whole — that the potash can not be recovered profitably for commer- 

 cial use. However, as the potassium salts are somewhat more solu- 

 ble than most of the other constituents of natural saline solutions, it 

 is believed that they are generally among the last to be deposited 

 when those solutions are evaporated. Owing to this selective action 

 of evaporation it is probable that somewhere in the saline residues of 

 completely desiccated lakes the potassium compounds will be segre- 

 gated in much richer concentrations than elsewhere. This condition 

 might not exist in natural saline deposits if the deposition of the 

 salines were interrupted by some event which permitted the escape of 

 the residual brines before all their constituents or final products were 

 deposited. But apparently in the playas of the Great Basin no such 

 event has interposed; hence all the constituents of the accumulated 

 brines must still remain, and it is believed that in certain favorable 

 places rich potassiurti-beariug salts exist. 



Most of the lakes that formerly existed in the Great Basin have 

 completely disappeared by evaporation. Vast quantities of saline 

 residues must have been deposited by the final drying up of these 

 lakes, but for the most part such deposits are not now seen at the 

 surface. It is believed that the,greater part of the salines deposited 

 simultaneously with the disappearance of the lakes has since been 

 buried by sediments carried into these basins by streams and depos- 

 ited as alluvial wash or in later lakes that have occupied the original 

 depressions. Older saline deposits elsewhere have been formed in a 

 similar way. 



If this hypothesis is sound, it follows that the probability of en- 

 countering saline deposits by drilling in the bottom of the desiccated 

 lake basins is very great and that under favorable conditions potas- 

 sium-rich sahnes will be among those encountered. It is hoped that 

 such buried salines may not in all places be so deep as to be 

 inaccessible. 



Field work undertaken by the Government in the search for pot- 

 ash has heretofore been largely of an exploratory character and has 

 not followed any general or established rule of procedure. A sys- 

 tematic study of brines, bitterns, and rock-salt deposit in all parts of 

 the United States is included in the general plan. The Geological 

 Survey has drilled a well approximately 1,000 feet deep near the 

 center of the Carson Desert, in northern Nevada. This test is not 

 regarded as completed. Elsewhere in Nevada and in California a 

 number of shallow drill holes have been sunk in other ancient lake 

 basins. Some of these experiments are yielding significant and 

 possibly important results. 



