From abstract: The Parkfield district, one of the minor California quicksilver districts, lies on the southern end of the Diablo Range, in the southeastern part of Monterey County and the westernmost tip of Kings County. (...) Two geologically similar areas, separated by 10 miles of unmineralized rocks, have been mapped. These areas contain (1) sedimentary, volcanic, and metamorphic rocks belonging to the Franciscan formation, of probable Jurassic age, (2) sedimentary rocks of Cretaceous age, (3) a few outcrops of fossiliferous strata assigned to the Temblor formation, of middle Miocene age, (4) large masses of serpentine emplaced along fault zones in post-Miocene time, (5) lenses of silica-carbonate rock formed by the alteration of the serpentine, and (6) large areas of landslide.

This report discusses geologic work conducted in the Strayton district, California on the deposits of quicksilver and antimony.

Report issued by the U.S. Bureau of Mines discussing safety hazards in western mines. Mine hoisting and haulage accidents are presented. Accident prevention is also discussed. This report includes tables.

Preface: The author of this paper gives a thorough description of a complex of very unusual igneous rocks and associated hydrothermal deposits.

Abstract: The manganese deposits of the Paymaster district, in Imperial County, Calif., extend along steeply inclined normal fault fissures which cut Tertiary (?) volcanic breccia and fanglomerate. The ore deposits are in part open-space fillings composed largely of psilomelane, and in part fault breccia replaced by psilomelane, pyrolusite, and manganite. Calcite and rock fragments are the chief impurities. High-grade ore now exposed averages about 40 percent manganese, and contains much barium. About 3,000 tons of ore averaging 42 percent manganese was produced from the district by hand-sorting in 1917-18. It is estimated that nearly the same amount could be produced again, largely from present workings. In addition, a few tens of thousands of tons of milling ore, estimated to contain between 10 and 30 percent of manganese, are believed to exist in veins one to three feet wide within one or two hundred feet of the surface.

From Introduction: "The present report is based on 10 weeks of field work from mid-November 1940 until late January 1941, and 4 days in May 1941. An area of 5 1/2 square miles in and about Del Puerto Canyon was mapped on a scale of 600 feet to 1 inch, and two small areas in the vicinity of the Adobe Canyon and Black Bart chromite mines were mapped on a scale of 200 feet to 1 inch."

Report discussing earthquake activity in the United States during 1942. The report is broken down by regions and has sections for specific earthquakes.