POTASH SALTS AND OTHER SALINES IN THE GREAT BASIN REGION. 



31 



The total Balines collected by the rivers of these four basins approximate 3,061,138 

 tons per annum. The contribution per square mile is given in the following table: 



Quantity of salines collected by rivers tributary to four important lake basins. 



Basin. 



Area. 



Quantity 



per square 



mile. 



Bonneville 



Sq. miles. 



49, 500 



40, 000 



3,200 



12,000 



Pounds. 

 96, 600 

 22, 880 

 63, 800 



Lahontan 



Owens 



Southern Oregon lakes - 



108, 720 









Average for four basins 





64, 800 









1 Estimated. 



These figures represent the most active basins, excepting the one in which Mono 

 Lake is situated. They may be taken as representing the northern and western parts 

 of the Great Basin. The southern half of the basin must contribute a very much 

 smaller amount of saline material to the sinks. 



While the above figures appear large and may be large, still when compared with 

 estimates from humid regions they do not appear unreasonable. Van Hise quotes 

 the estimate of T. Mellard Reade^ for the amount of salts per square mile per annum 

 for the whole globe as follows: 



Total, 192,000 pounds. Of this total, calcium carbonate is 10,000 pounds; calcium 

 sulphate, 40,000; sodium chloride, 16,000; silica, 14,000; magnesium carbonate, 8,000; 

 iron oxide, 2,000. Clarke ^ quotes the figures of Dole and Stabler^ for chemical denuda- 

 tion in the United States as 87 tons per annum per square mile. This would be 

 174,000 pounds and would apply to humid conditions. The figures given show that 

 the chemical denudation in the more active parts of the basin region is equivalent 

 to 37 per cent of this figure. 



Table XVII (Appendix) gives the salines in pounds for each square mile of water- 

 shed for the Truckee, Walker, Humboldt, and Owens Pavers. For purposes of com- 

 parison I have added the figures for five rivers in California. The figures show the 

 close relation betv/een run-off and salines removed per square mile. While the 

 saline content of the waters of a river in the semiarid region may be much higher than 

 for a river under humid conditions, the total salines collected in a given time from 

 a unit area is usually much less. This is easily explained by the fact that the greater 

 proportion of the surface waters is absorbed by alluvial material and their salts are 

 retained. The low yield of the Humboldt River is noteworthy. The very small 

 run-off is sufficient explanation. In general, the figures presented show that the 

 greater the run-off the greater the "crop" of salines from a unit area. Exception of 

 the Kern River and the San Ysabel Creek may be made. The character of the water- 

 shed and the rate of decomposition of the regional rocks enter as a factor. The greater 

 relative "crop" of these two streams is undoubtedly due to a greater rate of decom- 

 position of the rocks, or a greater amount of salines in the disintegrated rock upon 

 their watersheds. The water-duty factor, pounds of salines per square mile per 

 second-foot per annum, gives a better basis of comparison between rivers under arid 

 and rivers under humid conditions. Omitting the Kern and San Ysabel, since these 

 streams have exceptional conditions upon their watersheds, the streams of the basin 

 region show a much higher duty than those of the humid region in the near neighbor- 

 hood. To put it in another way, the same quantity of water on the Owens River 

 watershed would gather 4.5 times as much saline material as upon the Tuolumne, 

 and 3.2 times as much as upon the Truckee. 



The figures given can not be taken as the annual rate of chemical denudation for 

 the basin, for it must be kept in mind that the basin streams gather only a part of 

 the run-off waters, the remainder being absorbed in the sinks and basins. Expressed 

 as an equation — Pounds of salines liberated per square mile=pounds of salines 

 retained in soil and sinks -{-pounds gathered by rivers and discharged into lakes. 

 No data upon the amount of salts absorbed are available and, consequently, the sec- 

 ond number of this equation can not be quantitatively stated. The third number 



1 Treatise on Metamorphism, p. 486. 



2 Bui. No. 491, U. S. Geol. Survey, p. 103. 



