4:76 H. J. Biddle — Surface Geology of Southern Oregon. 



cient interest to justify their publication. This region was 

 reconnoitered by Mr. I. C. Russell in 1881 and 1882 ; and to 

 his description* reference must be had for a complete account 

 of its topography and surface geology. These notes are merely 

 intended to supplement some of the observations of that writer, 

 and to call attention to a few points not previously noted. A 

 portion of northern California, which has the same topograph- 

 ical features and geological structure as southern Oregon, is 

 included in the following observations. 



The first region to be considered is Warner Yalley. This 

 is a long, narrow valley, bounded on both sides by fault scarps 

 of grand proportions, and extending in a nearly north and 

 south direction. Its southern end is close to the point where 

 the dividing line between California and Nevada meets the 

 southern boundary of Oregon. This valley, as already not6d 

 by Russell,f was occupied by a Quaternary lake, which never 

 overflowed ; and in its lowest portions are, at present, a chain 

 of shallow lakes, and marshes. These lakes all drain, daring 

 the wet season, into the northernmost lake ; and are conse- 

 quently, with the exception of the latter, nearly or quite fresh. 

 The northernmost lake, on the contrary, is alkaline and brack- 

 ish. A sample of this body of water, collected in September, 

 was found to contain about four grams of solid matter to the 

 liter. Qualitative analysis showed the presence of sodium, 

 magnesium, traces of calcium and potassium, chlorine, sul- 

 phuric and carbonic acids, — the chief constituent being com- 

 mon salt. The salts contained in this lake do not, however, 

 represent the total amount left by the evaporation of the 

 ancient lake. On the east side of the valley, near its northern 

 end, is a group of ponds and marshes, the waters of which are 

 highly concentrated salt solutions. When dried by the heat 

 of summer they leave crusts of various salts. The common 

 salt from these ponds, though somewhat impure from the 

 admixture of sulphates, has become of importance to the 

 country round about; and several hundred tons are collected 

 annually for salting sheep and cattle. As the supply is 

 renewed every year, it is reasonable to infer that the salt is 

 derived from the sediments in the bed of the ancient lake, 

 which absorbed most of the salts left upon its desiccation. In 

 addition to sodium chloride, the waters of these ponds contain 

 a great quantity of sodium and magnesium sulphates, and a 

 trace of borax. In the mud beneath the ponds are crusts of 

 sodium sulphate, and nodules, up to three inches in diameter, 

 of a mineral which has the composition of Ulexite, a borate of 

 soda and lime. 



* Fourth Annual Report of the U. S. Geological Survey. A Geological Recon- 

 naissance in Southern Oregon, by I. C. Russell. 

 f Loc. cit., p. 459. 



