Annual report of the State Mineralogist for the year ending ... . ending from an altitude of five thousand eighthundred to two thousand three hundred feet above sea level. Midwaybetween these points the ridge branches, the northerly branch beingthe Iowa Hill Divide, and the southerly, or main branch, the ForestHill Divide proper. The general course is south of west, or approxi-mately normal to the axis of the main Sierra Range. At certain favorably located points an extended view is obtained ofthis and neighboring divides. Upon losing the effect of the detail onereceives the impression of a ge
Annual report of the State Mineralogist for the year ending ... . ending from an altitude of five thousand eighthundred to two thousand three hundred feet above sea level. Midwaybetween these points the ridge branches, the northerly branch beingthe Iowa Hill Divide, and the southerly, or main branch, the ForestHill Divide proper. The general course is south of west, or approxi-mately normal to the axis of the main Sierra Range. At certain favorably located points an extended view is obtained ofthis and neighboring divides. Upon losing the effect of the detail onereceives the impression of a general uniformity in the grades of thesummit-lines. These summit-lines appear as the remaining traces of agently undulating plane, sloping regularly from the bases of themassive peaks of the Sierra to the Sacramento Valley. One readilyconceives the idea that the deep canons and gulches, wThich give to themodern surface its broken and rugged character, are but the results ofthe prolonged erosive action of the present streams. Rgi. -CROSSSECT/ON-FOREST HILL DIVIDE. An examination of the district shows that the bases and main bodiesof these ridges are composed of metamorphic rocks of great age; andthat there are commonly exposed on the summits large accumulationsof volcanic material and extensive river deposits of a comparatively * A map accompanies this article. 436 REPORT OF THE STATE MINERALOGIST. recent geological epoch. In a popular sense, however, these depositare decidedly ancient, and they have been appropriately credited to aiancient river system. A characteristic cross-section of the Forest Hill Divide is given iiFig. 1. The Metamorphic Rocks forming the base and main body of the ridgtand constituting the country rock of the district are commonly slatescarrying seams and ledges of gold-bearing quartz. The slates vary ircharacter; they are finely laminated or coarse and blocky, talcose, argillaceous, or highly siliceous. There are several belts of soft laminatedslate in wh
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Keywords: ., bookcentury1800, booksubjectgeology, booksubjectminesandmineralr
