From introduction: The sampling on which the estimates of ore reserves in this report are partly based was done by Lasky and Roberts. The text was written by Lasky, who, except where otherwise noted, is responsible for any descriptions, comments, and conclusions concerning the area beyond the limits of the Hanna holdings, as well as for all statements concerning reserves and recommendations for future prospecting.

From abstract: Pt 1. The present work seems to confirm the genetic theory previously published, namely that [Illinois Cave in Rock] deposits were formed by ascending solutions. These solutions probably followed minor fissures that connected below with larger fissures, which in turn probably connected with a major fault zone. It is believed that where such minor fissures extended upward only to the shale or other impervious cap rock, or were greatly reduced in size where they penetrated such beds, the solutions spread laterally along the contact and along the limestone beds beneath it and replaced the limestone. Pt 2. This report is a presentation of the results of an electrical-resistivity survey conducted in the fluorspar-bearing areas of Hardin County, Ill., principally during the field seasons of 1934 and 1935.

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.

From introduction: The Red Bluff Bay area was examined briefly for the Geological Survey by John C. Reed and others in 1939. During the summer of 1941 the writers, with R. E. L. Rutledge, mapped this area on a scale of 1:12,000, and examined the serpentine masses in the interior during the course of reconnaissance trips into the surrounding region.

From introduction: In this study the Geological Survey and the Bureau of Mines, United States Department of the Interior, cooperated. The author prepared detailed geologic maps showing the surface topography, geology, and workings of 11 mines, and the underground workings and geology of 7 of these; the Bureau of Mines engineers directed diamond-drilling and.bulldozer-trenching. The locations of the detailed maps are shown on plate 23, an index map overprinted on a segment of the map made by Reed and Wells.

From preface: The manuscript of this report, which is the culmination of field and office studies carried on intermittently s' ice 1914, partly in cooperation with the Geological Survey of Georgia, was completed early in 1938. It was prepared with the expectation that it would form part of a more comprehensive report on the geology of Georgia by several authors, which was intended to accompany a geologic map of the entire State on a scale of 1: 500,000. However, this map without the text was published in 1939 by the Georgia Division of Mines, Mining and Geology. Part of this map is reproduced herein as plate 1 without revision.

From Introduction: The field work that furnished the basis for this report was begun in 1930 and was continued at intervals until 1934. The anticlinal character of the Kettleman Hills is apparent to even the casual observer, but the many structural complications due to an intricate network of minor faults, at least in North Dome and Middle Dome, are much less obvious. Though it is improbable that these faults have any relation to the occurrence of oil, an attempt was made to map them, not only to represent the structure adequately but also because the stratigraphy could not be understood if they were neglected. Faunal zones were particularly useful in mapping. On the other hand, some lithologic units proved to be more persistent than had been expected. The two sets of features-fossils and lithology-served as checks on each other.

Introduction: Part 2 of the Systematic Report continues and concludes the study of the Mollusca from the Miocene and lower Pliocene of Virginia and North Carolina. One hundred and nineteen species, only a fraction of the known fauna, are reviewed and 66 additional species are described and figured. (See faunal chart, pp. 180-183.) The report upon the gastropods suffers from the same shortcomings obvious in the work on the pelecypods. Most of the material is from old collections made before the importance of the exact placing of the fossil locality both areally and vertically was recognized. Many of the citations of outcrops are vague and the sections generalized. Detailed field studies, particularly on the zoning of the Yorktown formation in southern Virginia and northern North Carolina, were begun later by Wendell P. Mansfield, but he died in the summer of 1939 before the completion of the work.

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.

This report is part of a series describing the structural features, the character of the oil- and gas-producing beds, and the localities where additional oil and gas may be found in parts of Osage County, Oklahoma. This part discusses the geology and resources in the northeastern part of the county, along the Oklahoma-Kansas boundary.

This report is part of a series describing the structural features, the character of the oil- and gas-producing beds, and the localities where additional oil and gas may be found in parts of Osage County, Oklahoma. This part discusses the geology and resources of the Burbank and South Burbank oil fields, in the northwestern part of Osage County and the eastern part of Kay County.

From Introduction: "Scattered throughout the Colorado Front Range, there are many small copper deposits, believed to be of pre-Cambrian age. The have been widely prospected but have produced little or no ore. In one of these, the Copper King mine, near Gold Hill, Colo., nickel was discovered in 1930, and development in the following years has exposed some 25,000 tons of ore containing from 2 to 3 percent of nickel. No other nickel deposit is known in the Front Range, but a somewhat similar deposit has been opened in Gem mine, near Canon City and about 120 miles south of Gold Hill."

From introduction: The object of this paper is to describe the salient features of Jurassic diastrophism in parts of the Tonopah and Hawthorne quadrangles in west-central Nevada. The problem is complicated by the lack of continuity of exposures, earlier folding of the older rocks, metamorphism caused by the later granitic in-trusions, and by superposed Tertiary and later normal faults.

This report is part of a series describing the structural features, the character of the oil- and gas-producing beds, and the localities where additional oil and gas may be found in parts of Osage County, Oklahoma. This part discusses the geology and resources along the southern border of the county, encompassing Osage and Pru, Oklahoma.

This report is part of a series describing the structural features, the character of the oil- and gas-producing beds, and the localities where additional oil and gas may be found in parts of Osage County, Oklahoma. This part discusses the geology and resources in the southeast corner of the county, adjacent to Tulsa.

This report describes results of a field study in the Shafter mining district and conclusions presented are drawn from field studies along with office studies.

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

Report describing the characteristics of manganese deposits found in White Pine County, Nevada, and geographic information about the surrounding area.

From abstract: The Blue Wing district, Lemhi County, Idaho, is not only the principal tungsten mining district in the State but it has recently become one of the leading producers of tungsten in the United States. So far only one mine in the district is productive, but other prospects are being actively developed.

From introduction: This paper describes the geology of a part of the Alaskan Range that lies in the headwater region of the Copper and Tanana Rivers.

From Introduction: "The recent large increase in gold production from the Alma district has greatly stimulated interest in territory immediately to the east, where many small gold-bearing veins have been discovered. Consequently, as a cooperative project of the United States Geological Survey and the State of Colorado, 7 weeks in 1938 were devoted to renaissance work to determine the origin of the placer gold and the possibilities for discovering valuable lode deposits either near the surface or at depth."

From introduction: The present report aims to supply additional information regarding the Tertiary deposits, which are the source of most of the gold placers now being worked in that part of the Eagle-Circle district lying south of the Yukon River. The work was conducted from base camps along the river, but the belt of Tertiary rocks is at places as much as 20 miles from the Yukon, so that it is not easily accessible from the river except in the vicinity of mining camps, where roads or trails have been constructed southward.

This report is part of a series describing the structural features, the character of the oil- and gas-producing beds, and the localities where additional oil and gas may be found in parts of Osage County, Oklahoma. This part discusses the geology and resources in the northeastern part of the county.

Abstract: The presence of cinnabar in the Wild Horse district, in western Lander County, Nev., has been known since about 1916, but little ore was produced until 1940. In that year and early in 1941, deposits discovered in 1939 were mined to apparent exhaustion by the Wild Horse Quicksilver Mining Co., which had produced 827 flasks at the end of April 1941. The district is underlain by moderately deformed sandstone, shale, and limestone of Lower and Middle Triassic age, locally covered by remnants of a mantle of Tertiary fanglomerate, tuff, and lava. The Triassic rocks are partly silicified, and cinnabar has been found in and near silicified rock, particularly the silicified limestone at the base of -the Middle Triassic. The ore bodies so far discovered were individually small and ill-defined, and had an average tenor of less than 0.5 percent of quicksilver. Other similar ore bodies are to be expected at moderate depths, but the cost of exploration for them may, perhaps, prove excessive.