GKEAT SALT LAKE. 435 



are unusually insoluble, and that those which are brought in b}^ the trib- 

 utary streams are almost immediately thrown down. That lime has been, 

 in solution in the waters is proved by the peculiar sands found on the beach 

 at various points, notably at Black Eock Point and along the southern end 

 of the Terrace Mountains. These sands are made up of little spherical 

 grains of white, opaque carbonate of lime, up to one-tenth of an inch in 

 diameter. An analysis made of them by Mr. R. W. Woodward gave the 

 following results : 



Ferric oxide and alumina 0.25 0.29 



Lime 51.39 51.44 



Magnesia 0.82 1.02 



Soda 0.77 0.73 



Potassa 0.36 0.32 



Sulphuric acid 0.52 0.53 



Carbonic acid 40.74 40.74 



Chlorine trace trace 



Water 1.28 1.28 



Insoluble residue 3.88 3.85 



100.01 100.20 



Under the microscope, they are seen to have a rudely concentric struct- 

 ure, and may therefore be considei'ed to be a concretion formed around 

 some nucleus perhaps of organic origin, or perhaps some minute grain of 

 siliceous sand. As has already been mentioned, similar deposits have been 

 found in the Tertiary beds of the Green River Basin, compacted into a rock, 

 and in some cases silicified. 



The \sike contains no fish, and was long supposed to be absolutely de- 

 void of animal life, although the tributary streams abound in fresh-water 

 fish, such as perch and trout, and the latter are even found in the Hot 

 Spring La,ke. Mr. Sereno Watson, of this Survey, has, however, discov- 

 ered a minute crustacean which inhabits its waters, and which has been de- 

 scribed by Prof. A. E. VerrilP as Artemia fertlUs. The shores of the lake 



'Am. Jour, of Sci., Nov., ISGO. 



