Geology topics
Research about Powder River basin
Source-linked reports with geographic coverage including Powder River basin.
Lithofacies map, cross section, and favorable areas for uranium deposits, Powder River basin, Wyoming and Montana
No abstract available.
Thickness, percent sand, and configuration of shallow hydrogeologic units in the Powder River basin, Montana and Wyoming
No abstract available.
Long-term highwall stability in the northwestern Powder River basin, Wyoming and Montana
Time-dependent behavior of natural and and excavated slopes in sedimentary rocks is a subject that is poorly understood at present but that is now an important consideration in the design, operation, and reclamation of energy-extraction facilities, in part because of the environmental considerations mandated by the Surface Mining Control and Reclamation Act of 1977 (Public Law 95-87.) A slide in an abandoned, unreclaimed strip mine northwest of Sheridan, Wyoming, has been analyzed as an example of a long-term slop failure in the region. This slide occurred in early 1975, some 20 years after cessation of mining. This investigation used Spencer's limiting equilibruim method and an elastic-plastic finite element method incorporating the Drucker-Prager yield criterion.
Climate appraisal maps of the rehabilitation potential of strippable coal lands in the Powder River basin, Wyoming and Montana
No abstract available.
Effects of coal mine subsidence in the western Powder River basin, Wyoming
Analyses of the surface effects of past underground coal mining in the western Powder River Basin suggest that underground mining of strippable coal deposits will damage the environment more over long periods of time than will modern surface mining, provided proper restoration procedures are followed after surface mining. Subsidence depressions and pits are a continuing hazard to the environment and to man's activities 5-20 km north of Sheridan, Wyo., above mines that were abandoned 25-80 years ago where the overburden is weak and is less than about 60 m thick. In addition, fires commonly start by spontaneous combustion when water and air enter the abandoned mine workings via subsidence cracks and pits. The fires can then spread to unmined coal as they create more cavities, more subsidence, and more cracks and pits through which air can circulate. In modern surface mining operations the total land surface underlain by minable coal is removed to expose the coal. The coal is removed, the overburden and topsoil are replaced, and the land regraded and revegetated. The land, although disturbed, can be more easily restored and put back into use than land underlain by abandoned underground mine workings in areas where the overburden is less than about 60 m thick. The resource recovery of modern surface mining also is much greater than that of underground mining procedures. Although present-day underground mining technology is advanced as compared to that of 25-80 years ago, subsidence resulting from mining of thick coal beds beneath overburden less than about 60 m thick by underground methods can cause greater damage to surface drainage, ground water, and vegetation than can properly designed surface mining operations. This report briefly discusses the geology and surface and underground effects of former large-scale underground mining in a 50 km2 area north of Sheridan, Wyo. and describes some environmental consequences and problems caused by mining.