Core logs from Searles Lake, San Bernardino County, California

Abstract

Forty-one drill holes in the saline deposit on Searles Lake, San Bernardino County, Calif., were cored and logged. Drill holes averaged about 100 feet in depth; the majority are located around the margins of the dry lake. The saline deposit consists of an upper salt body about 39 square miles in area, of which 12 .sqtiare miles are exposed in the central part of the lake, and a lower salt body of approximately the same areal extent found at greater depth. The 2 salt bodies are separated by a seam of clay or marl averaging about 12 feet thick. Isopach maps show the salt bodies are slightly elongated to the north; maximum thicknesses of the upper and lower salt bodies are 95 and 54 feet, respectively. Core logs, in written and graphic form, show the chief minerals of the saline bodies are halite, trona, hanksite, borax, and burkeite; relatively minor quantities of 13 additional minerals are described. The 41 drill-hole logs are shown graphically in columnar sections which give thicknesses, mineralogy, and mineral percentages; 15 representative written logs are published in full. GEOLOGIC INVESTIGATIONS IN MOJAVE DESERT REGION ACKNOWLEDGMENTSThe drilling program was carried out with the cooperation of the American Potash & Chemical Corp., the West End Chemical Co., the Searles Lake Chemical Corp., and the San Bernardino Borax Mining Co., Ltd., all of whom permitted drilling of their properties on Searles Lake.Microscopic and X-ray determinations of many mineral specimens were made by Robert D. Alien, of the Geological Survey.About 1,200 samples were taken by the writer for chemical analysis. These chemical determinations, chiefly for boron, were made by Henry Kramer, Sol Berman, and Hy Almond, chemists, of the U. S. Geological Survey. Results of these chemical analyses are in CORE LOGS FROM SEARLES LAKE, CALIFORNIA 143