Geology of Black Butte, Los Angeles County, California. Geology of the Puente Hills

Abstract

Geology of Black Butte, Los Angeles County, California The area studied lies directly on the First Standard Parallel North of the San Bernardino Base and Meridian in the Black Butte Quadrangle, Los Angeles County, California. Black Butte is about 125 miles by auto northeast of Los Angeles. The size of the area is about 1 square mile, with a relief of approximately 600 feet. No part of the area has been put under culture. The field work was conducted by topographic location and with Brunton compasses insofar as was practicable. Five days were spent in the field. The work was undertaken to give the author experience in igneous geology. Geology of the Puente Hills The area described in this report, is that part of the Puente Hills, California, lying to the north and west of the Turnbull Canyon road, and is the extreme western end of this range of hills. The area is most readily reached by the Turnbull Canyon road from the town of Whittier, which lies about two miles to the southwest. Whittier is some thirteen miles east of Los Angeles. The area in question lies on the common corner of the El Monte, Puente, Whittier, and La Habra quadrangles, and has an area of about four square miles. A small portion (perhaps five percent) is under cultivation with citrus and avocado orchards. Approximately ninety percent of the total area is grazing land for sheep, horses, and dairy cattle. The remaining five percent is covered with sage and other brush. The relief is about 1200 feet, the elevations ranging from 250 to 1400 feet. The drainage in this particular portion of the Puente Hills is east and west, since a long ridge trends almost due north across the area. The topography appears to be in early maturity. Outcrops are fairly abundant, but in many cases do not lend themselves readily to giving a dip and strike. The field work was done with a topographic map by the U.S.G.S., and a Brunton compass. Fifteen days were spent in the field.