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Research about Black Hills

Source-linked reports with geographic coverage including Black Hills.

54 records · Page 3Linked to original sources
USGS1975

The Black Hills-Rapid City flood of June 9-10, 1972: A description of the storm and flood

On June 9, 1972, an almost stationary group of thunderstorms formed over the eastern Black Hills of South Dakota near Rapid City and produced record amounts of rainfall and flood discharges. Nearly 15 inches of rain fell in about 6 hours near Nemo, S. Dak., and more than 10 inches of rain fell over a 60-square-mile area. The resulting floods were the highest ever recorded in South Dakota. At least 18 of the 27 streams where peak flows were computed experienced flows that exceeded the 50-year flood. At least 237 people died in the Black Hills flood and 8 people were still listed as missing 6 months after the flood. Another 3,057 people were injured, and total damage is estimated to have exceeded $160 million. As documented by radar and' satellite images and by radiosonde observations, as well as by much other weather data, the unusual and excessive rainfall was partly the result of a strong, low-level, easterly airflow that forced moist air upslope over the Black Hills. This sustained orographic effect helped the air to rise, cool, become very unstable, and release its moisture in repeating -thunderstorms. Another important contributing factor was the unusually light winds at higher levels. Those light winds did not disperse the moist air or move the thunderstorms along to prevent the extreme concentration of rainfall. Instead, these conditions allowed heavy rainfall to remain almost stationary along the eastern slopes of the Black Hills. Rainfall data from 24 observing stations and from over 200 miscellaneous sites show that all reported rains greater than 4 inches fell on the eastern slopes of the Black Hills. At least 6 inches of rain fell over a 300-square-mile area that lies primarily between 4,000 and 5,000 feet elevation. Almost all the flood peaks occurred between 2230 MDT on June 9 and 0100 MDT on June 10, 1972, in a flood belt about 40 miles long and 20 miles wide along the eastern slopes of the Black Hills. This belt extended from Sturgis, S. Dak., on the north to Hermosa, S. Dak., on the south, with Rapid City near the center. To document the flood, peak discharge determinations were made at 49 sites. Records show that about 13,000 acre-feet of water flowed through Rapid City during the 2 days of flooding. At one point during the night of June 9, the floodwaters rose about 3.5 feet in 15 minutes. Coming off the slopes of the Black Hills, the flood peak traveled the 22 miles between Deer Creek and Rapid City in about 3.5 hours.

South Dakota↗
USGS1963

Stratigraphic sections and correlation of beds in the Inyan Kara Group and Morrison Formation, north end of the Black Hills, Crook County, Wyoming, and Butte County, South Dakota

Descriptions of 47 stratigraphic sections of the Ivan Kara Group and Morrison Formation are given for an area extending from bluffs on the west side of the Belle Fourche River in T. 56 N., R. 64 W., Crook County, Wyo., southeastward across the Bear Lodge Mountains to a point in T. 8 N.,R. 1 E., Butte County, S. Dak.--a distance of about 35 miles. Also given are four sections measured farther southeast in the area between Belle Fourche and Rapid City, South Dakota. The Morrison, Lakota, and Fall River Formations are each subdivided into two parts and the subdivisions are correlated for most of the area.

South Dakota, Wyoming↗
USGS1960

Structure associated with rock creep in the Black Hills, South Dakota

Many areas of schist in the southern Black Hills, South Dakota, have a thin zone of disintegrated rock that is 4-10 feet below the ground surface and parallel to it. Fresh, undeformed schist overlying this zone has moved downhill in a mass-wasting process since the present surface was formed.

South Dakota↗
USGS1956

Alteration of sandstone as a guide to uranium deposits and their origin, northern Black Hills, South Dakota

Several uranium deposits are present in the Fall River sandstone of Early Cretaceous age on the northeast flank of the Black Hills, Butte County, South Dakota. The deposits are within a fine-grained, well-sorted, persistent basal sandstone unit that ranges in thickness from 2 to 18 feet and dips about 4° NE. Detailed mapping of about 2 square miles surrounding the deposits have shown that all the uranium occurrences and most of the areas of high radioactivity are where the color changes in the basal sandstone from reddish on the up-dip side of the the occurrences to yellowish-gray or buff down-dip. Radioactivity measurements show that uranium is distributed almost continuously along the sinuous red-buff contact for more than 5 miles. Laboratory work indicates that the red color is caused by the hematite resulting from the alteration of ferrous iron minerals and hydrous ferric oxides. The close association of the red-buff contact and the uranium deposits suggest that the two were formed by the same solutions. The uranium was probably deposited originally from ground water which moved down-dip and gradually changed from an oxidizing solution near the surface to a mildly reducing solution at depth. Concentrations of uranium have resulted from the localization of reducing conditions cause perhaps by structures superimposed on the regional dip, local thinning or decrease in permeability of the sandstone, or concentrations of pyritiferous carbonaceous material. The red alteration is probably the result of pre-Oligocene weathering that has extended downward in the more permeable beds about 200 feet below the ancient erosion surface. Oxidation of the primary uranium during the present weathering cycle has resulted in the formation of carnotite and possibly other secondary uranium minerals.

South Dakota↗
USGS1955

Geology of the northern Black Hills bentonite mining district

Extensive deposits of bentonite are present in the Cretaceous sedimentary rock strata cropping out on the northern flank of the Black Hills. These deposits have been the subject of a study by the U.S. Geological Survey as part of the program of the Department of the Interior for appraisal of natural resources of the Missouri River Basin. This report contains information concerning the geology of the bentonite deposits of the Northern Black Hills district. An attempt is made to explain some of the relations that exist between the physical properties and the mineralogical characteristics of the bentonite. Consideration is given to the occurrence of bentonite deposits and different types of sedimentary rocks and to depositional and post-depositional conditions which these rocks reveal. Evidence for sources of ancestral materials and conditions of alteration are discussed.

Black Hills↗
USGS1909

Geology and water resources of the northern portion of the Black Hills and adjoining regions in South Dakota and Wyoming

This paper, which supplements the report on the geology and water resources of the southern half of the Black Hills, published in 1901, is the result of studies made at intervals during the years 1899 to 1907. It relates to an area of about 7,500 square miles, situated about half in South Dakota and half in the northeast corner of Wyoming (Pl. II), and covering the northern half of the Black Hills uplift and a wide area of adjacent plains. The report describes the geology of the sedimentary rocks - their stratigraphy, structure, and history - and discusses their mineral resources, including underground water, coal, gypsum, etc. It also contains information respecting surface waters available for irrigation and stock raising, timber, climate, and the history of the topographic development of the region. The crystalline rocks of the central portion of the Black Hills area and the various igneous rocks of later age are shown on some of the accompanying maps but without differentiation, as the study of their geology was not within the scope of the investigation; neither are their mineral resources considered here, for these are treated in other publications. In the field work I have been assisted mainly by Prof. C. C. O'Harra, of the School of Mines at Rapid, who has mapped the geology of large areas about Aladdin, the Devils Tower, Belle Fourche, and Rapid. Dr. W. S. Tangier Smith has mapped portions of the Bear Lodge and Nigger Hill uplifts, and Mr. C. A. Fisher has assisted in portions of the work. The geology of the region from Sturgis to a point beyond Spearfish Canyon was mapped by Prof. T. A. Jaggar, jr., with the assistance of Mr. J. M. Boutwell, in 1898 and 1899. It is desirable to repeat here the statement made in my previous report that all who study the geology of the Black Hills must feel impressed by the remarkably clear general conceptions of the geologic relations of this region afforded by the survey made by Mr. Henry Newton over a quarter of a century ago. In one short season, with many unfavorable conditions for traveling, he determined most of the broader features and recorded many of the essential details. His posthumous report, edited by Mr. G. K. Gilbert, will always remain a standard work on Black Hills geology. Later studies have added greatly to our knowledge of the details of the stratigraphy and structure, the distribution of the rocks and minerals, and the age of the beds, and have afforded means for a more complete elucidation of the geologic history, especially the physiographic development of the Black Hills region.

South Dakota, Wyoming↗
USGS1904

Economic resources of the northern Black Hills

The mining district of the Black Hills comprised within the Spearfish and Sturgis quadrangles was surveyed geologically in the summers of 1898 and 1899 under the direction of Mr. S. F. Emmons. The following pages present a brief summary of the geologic features, more especially with reference to ore-bearing formations. These are confined to the Algonkian and Paleozoic strata and their associated eruptives.

South Dakota, Wyoming↗