(J8 



GEOLOGICAL BISTOEY OF LAKE LAHONTAN, 



desert near Brown's Station was found by Mr. R. W. Woodward to have the 

 following composition :'*" 



NORTH CAKSON LAKE. 



This lake is situated on the northern part of the Carson Desert (see 

 Plate VII) and receives its waters from both the Humboldt and the Carson 

 rivers. Having no outlet, the waters flowing into it have been supposed to 

 sink, and for this reason it is generally spoken of as the "Humboldt and 

 Carson Sink." As this term is based on an error, we have used the name 

 "North Carson Lake" instead. 



During the winter and spring it receives a considerable supply of water 

 from both the Humboldt and Carson rivers, and becomes a shallow playa- 

 lake, between 20 and 25 miles in length, by 14 miles in breadth. In unu- 

 sually arid summers the water supply fails, and the lake evaporates to dry- 

 ness. As desiccation becomes more intense the salts impregnating the lake- 

 beds are brought to the surface and form an efflorescence several inches in 

 thickness. 



This was the case when the Carson Desert was visited by the writer in 

 October, 1881. The lake had then wholly evaporated, leaving a broad mud- 

 plain covered in places with a white alkaline crust that looked like patches 

 of snow. 



SOUTH CARSON LAKE. 



Situated on the southern border of the Carson Desert lies South Car- 

 son Lake. This, like the larger lake to the northward, is a playa-lake and 

 occupies a ver}' shallow depression in the lake-beds flooring the desert. 

 Like other lakes of its class, it has indefinite boundaries and varies in size 



^"U. S. Geological Exploration oi' tlip Fortu'tb rarallel, Vol. II, ii. 744. 



