Geologic report of Black Butte, Antelope Valley, California. Geologic report of the Puente Hills, California

摘要

I. The Black Butte is a distinct hill among other remnant hills in the southern Antelope Valley. Nearly all the other buttes in the vicinity are grayish tan in color and consist of granite cut by numerous splite and pegmatite dikes. The Black Butte has, besides this granite massif, a cap of diorite which weathers black and hence gives the hill its name.ududII. A portion of the Puente Hills west of the Pass and Covina Road and east of the town of Puente comprises the area. The structure under the hills are an anticline plunging to the west, a fault running north, and south through the center of the area, and overturning to the north of the eastern portion of the fold. Two rock types, shale and conglomerate, of upper Puente Formation of Upper Miocene time, comprise the area.ud