From introduction This report describes large-scale depositional units referred to as architectural elements, interpreted from outcrops of three distinct fluvial sandstone units of the Lakota Formation in the southwestern Black Hills area of Custer and Fall River Counties, South Dakota. These fluvial deposits formed near the end of an episode of continental deposition that began when the Jurassic Sundance sea regressed from the region and ended when the Early Cretaceous Skull Creek sea encroached from the north in Albian time.

From abstract: This report contains complete Bouguer anomaly, isostatic residual anomaly, and horizontal gradient anomaly gravity maps of the Powder River Basin and surrounding areas in southeastern Montana, northeastern Wyoming, and western South Dakota were compiled using gravity data from 21,528 stations. A total-intensity anomaly aeromagnetic map with 3 mile spaced east-west flight-lines is also presented. Also included is an analysis of these maps and data, focusing on gravity and aeromagnetic studies.

From introduction: This report describes the results of 1980 sampling of ground-water pumpage for irrigation on the High Plains, one phase of the High Plains Regional Aquifer-System Analysis project. These data were collected to estimate the volume of irrigation water pumped during 1980 and to determine current trends in irrigation pumpage on the High Plains.

From purpose and approach of study: The purpose of this study was to use the digital-computer model developed from the previous study (Koch, 1982) to examine the effects on the aquifer of a pumping rate of 25 million gallons a day under the worst-drought conditions that occurred during 1974-78. A frequency rating was determined for the most severe low-flow condition in the Big Sioux River.

From introduction: The overall purpose of this study were twofold: (1) To determine where greatest yielding wells at shallowest depths would produce water of suitable quality for municipal and industrial supplies; and (2) to determine regional effects of additional water development on the hydrologic system.

From objectives and scope: The objectives of this study were to more accurately define certain hydrologic and hydraulic characteristics of the James River and its tributaries in South Dakota, to analyze the water budget and water quality within the Sand Lake National Wildlife Refuge, and to identify the need for additional studies.

Purpose: The objectives of this study were (1) to collect, synthesize, and interpret geologic and hydrologic data on the aquifer in the southern South Dakota area; (2) to evaluate, by digital-computer-model simulation, values assigned to the aquifer parameters; and (3) to evaluate the sensitivity of the calibrated digital-computer-model to changes in magnitude of the selected hydrologic parameters. Results of this study are, therefore, applicable to solving potential water-resource management problems in the southern South Dakota and northern Nebraska model area.

From introduction: In July 1977, the South Dakota Geological Survey and the U.S. Geological Survey began a 4-year study to evaluate the water resources and geology of Hanson and Davison Counties. The purpose of this report is to provide hydrogeologic information for future water development and planning in the counties. This study is part of an evaluation of the water resources and geology of eastern South Dakota (fig. 1).

From abstract: The High Plains Regional Aquifer System Analysis study has developed a regional water-resources (and related) data storage and retrieval system to organize and preserve areal interpretive data. The system is general and can easily be adapted for other studies. This report documents the High Plains data base as well as the general system that is independent of the High Plains area.

From purpose and approach of study: The purpose of this study was to develop a predictive model of the ground-water system for use as a management tool. The model will be used by State and local officials in evaluating the effects of alternative methods of controlling or developing the ground-water resources of the Big Sioux aquifer in Minnehaha County.

Abstract: This report lists the machine-readable data files developed for the Madison Limestone and Northern Great Plains Regional Aquifer System Analysis (RASA) projects that are stored on magnetic tape and available from the U.S. Geological Survey. Record format, file content, and size are given for: (1) Drill-stem-test data for Paleozoic and Mesozoic formations; (2) geologic data from the Madison Limestone project; (3) data sets used in the regional simulation model; (4) hydraulic-head data for the Lower and Upper Cretaceous aquifers; and (5) geologic data for Mesozoic formations of the Northern Great Plains.

From introduction: "The U.S. Geological Survey began a 5-year study of the High Plains regional aquifer during the 1978 to provide the hydrologic information needed for the development of computer models to evaluate the aquifer's response to ground-water management alternatives." It contains maps, graphs, and tables.

Abstract: A digital simulation model was used to analyze regional ground-water flow in the Madison Group aquifer in the Powder River Basin and adjacent areas. Most recharge to the aquifer originates in or near the outcrop areas of the Madison in the Bighorn Mountains and Black Hills , and most discharge occurs through springs and wells. Results from the model calculations indicate that the total flow through the aquifer in the modeled areas was approximately 200 cubic feet per second (5.7 cubic metres per second). The aquifer can probably sustain increased ground-water withdrawals probably would significantly lower the potentiometric surface in the Madison aquifer in a large part of the basin. The digital model could better predict the effects of withdrawals if more accurate estimates of the storage coefficient, transmissivity, and leakance could be obtained.

From introduction: This is a progress report on regional stratigraphic and paleontologic studies of the Upper Cretaceous Montana Group and equivalent rocks in the northern part of the western interior of the United States. It presents preliminary data on the positions of strandlines during a 14-m.y. (million year) span of the Late Cretaceous as well as our interpretations of the geologic history of this period.

From abstract and introduction: Mineralogic and stratigraphic studies of the lower part of the Pierre Shale of Late Cretaceous age along the Missouri River indicate correlations different from those generally accepted. The purposes of this paper are to present evidence for the new correlations and to resolve problems of formal nomenclature that result from them.

A report about sandstone in the black hills of Wyoming and South Dakota. It discusses the nonopaque heavy minerals found within it.

The following report describes the examinations of the nonopague heavy minerals in sandstone found in the Black Hills in northeastern Wyoming and western South Dakota. The studies were made to determine if differences in the shapes of the grains and proportions of minerals are sufficiently distinctive to be used in subdividing and correlating formations.

From introduction: This study was part of the U.S. Geological Survey's continuing study of the geology and ore deposits of the southern Black Hills, which was stimulated by the discovery of uranium deposits in sandstone in the area in 1951 (Page and Redden, 1952; Bell and Bales, 1955).

From introduction: This report evaluates four possible types of subsurface reservoirs for radioactive wastes in the Williston basin.

From abstract: The northern Black Hills bentonite mining district includes parts of Crook County, Wyo., Carter County, Mont., and Butte County, S. Dak. Within this district, many beds of bentonite occur interspersed with sedimentary strata of Cretaceous age that have an average total thickness of about 3,000 feet and consist chiefly of marine shale, marl, and argillaceous sandstone. The bentonite beds occur in formations ranging upward from the Newcastle sandstone to the lower part of the Mitten black shale member of the Pierre shale. Tertiary (?) and Quaternary deposits of gravel, sand, and silt are present on extensive terraces, and deposits of such materials also extend along stream courses in all parts of the district.

Report discussing the geology and pegmatites of the Fourmile Quadrangle, located on the southwest side of the Black Hills uplift in Custer County, South Dakota. "This report is an abstract of a paper with the same title that is planned for publication as a Geological Survey professional paper."

The following report covers studies and investigations of uranium deposits in the Black Hills of South Dakota and Wyoming. The ore minerals include carnotite, tyuyamunite, metatyuyamunite, corvusite, rauvite, uraninite, and coffinite, as well as minor amounts of other uranium and vanadium minerals.

The following report covers the Petrographic study of Early Cretaceous age sandstone beds in the Fall River formation and the Fuson-Lakota formations, as well as Late Jurassic age beds in the underlying Unkpapa and Morrison formations along the western side of the Black Hills.

A report regarding petrographic study of sandstone of the Inyan Kara group and associated rocks in the Black hills, Wyoming and South Dakota