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Show 180 Eruptive granite- At the Saline Flats of the Mohave River, at Dead Mountain, and in the Opal ranges, granite appears under circumstances indicating the eruptive character of the rock. FIG. 2.- From Buena Vista Mountain. Eruptive dtortte.- Two narrow dioritic dikes, 2 to 3 feet thick and but about 15 distant from each other, traverse the calcareous sandstone of palaeozoic age ' near Duck-weilei Station, at Owens Lake, in such a manner that the phenomenon strikes even those who never were devoted to observations in nature most impressively, ( see Fig. 3.) At the contact- surface of the eruptive and the sedimentary rock, the latter is fritted and very bard, ( so- called porcelain jasper,) due to the metamorphosis produced by the heat of the erupted rock. FIG. 3.- Section in vicinity of Owen's Lake. P, sandstone wall, 30 feet high ; strata dipping at an angle of 24° toward the east; D, dikes of diorite. In the vicinity of the mining- town I van pah, in the Opal Mountains, aud farther east, at Mount Newberry, on the Colorado River, dikes of diorite in granite are very extensive, and the rock assumes in part a porphyritic structure. At Chuokavalla Peak, in San Diego County, occurs an eruptive rock of the appear- |