332 University of California Publications. [Geology 



this point of view the descent of the water plane in the Egan 

 Eange would be the subterranean correlative of the last desic- 

 cation of Lake Bonneville. The discriminating test between the 

 two suggestions above made as to the lowering of the ground 

 water would be the generality of the phenomenon. If, in va- 

 rious mines distributed over the Great Basin, it should be found 

 to be a fact that the ground water has in general been lowered 

 to a similar extent, then local causes would be eliminated except 

 as modifying conditions, and the general cause, the advent of 

 arid conditions, would seem to be the true explanation. If such 

 should prove to be the case, it would be an interesting addition 

 to the accumulating facts which go to show a definite dependence 

 of certain important features of ore deposits upon climatic 

 conditions. 



The temperature of the mine water at the bottom of the in- 

 clined shaft on June 15, 1904, was determined to be 16° C. A 

 sample of the water had previously been sent to San Francisco 

 and was there analyzed by Dr. Harry East Miller, with the re- 

 sult tabulated below. It is probable that the proportion of ferric 

 sulphate is higher than is actually the case in the mine owing 

 to the difficulty of preventing oxidation of the ferrous salt. The 

 result is interesting as an indication of the materials which are 

 being leached from the porphyry by the descending meteoric 

 waters. There is no evidence or suggestion of ascending waters 

 in the mine at present. 



ANALYSIS OF MINE WATER AT THE RUTH MINE. 



Grains per Gallon of 

 231 cu. in. 



Si0 2 + insoluble matter 5.50 



NaCl 4.88 



KC1 . 55 



FeS0 4 5.77 



Fe 2 (S0 4 ) 3 8-78 



K,S0 4 2.96 



CaS0 4 20.99 



MgSO< 7.61 



Organic matter + water of sulphates 6.96 



64.00 



