CHAPTEH YI. 



DESCRIPTIVE GEOLOGY OF THE CLEAR LAKE REGION. 



[Atlas Slioct III.] 



General character. — Clear Lake IS ail iiTegular and picturesque slieet of 

 water, l^-ing at an elevation of 1,310 feet^ in the heart of the Coast Ranges. 

 Manv of the surrounding hills rise to an elevation of about one thousand 

 feet above the level of the lake, but the dominant feature of the seenery 

 is the prominent mass of Konocti (or Uncle Sam), the summit of which, as 

 measured by Mr. J. D. Tloft'inanii, stands 2,936 feet above the lake at high 

 water (ilarch, 1884). Konocti is a group of volcanic cones considerably 

 eroded, but retaining clear traces of its original form, to which it approxi- 

 mates as nearly as do Mt. Shasta and Mt. Hood.' Like those mountains, 

 too, it is composed of andesites of the group called asperites in a preceding 

 chapter and is probably of very nearly the same age. I'he peaks are 

 rocky and the declivit}' toward the remarkable basin of Little Borax Lake 

 is precipitous. The eastern flank also is steep and the rock is exposed to 

 view over a wide area. Here it is scored with three sets of concentric line.=, 

 which sweep across the mountain side in graceful cnrves and mark series 

 of bedded hows of the lava composing the mass. The lower portions of 

 Konocti and a very large proportion of the ranges of the district are 

 densely clothed with brush, chiefly dwarf oaks, chamisal, and manzanita. 

 These remain green throughout the summer and mitigate the impression of 

 drought wdiich the scenery in general creates. They also afford a refuge 



' Determined by Mr. R. K. Nichols for the Clear Lake Water Company. 



^ See ray paper "Ou the geometrical form of volcanic cones," Am, Jour. Sci., 3il series, vol. 30, 188.'), 

 p. 283. 



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