Sharps Formation — LLMpedia

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Sharps Formation is a Paleogene lithostratigraphic unit in the Great Plains of the United States, principally exposed in southwestern South Dakota and adjacent Nebraska. It is a component of the White River Group and has been central to studies by institutions such as the Smithsonian Institution, University of Nebraska–Lincoln, South Dakota School of Mines and Technology, and the American Museum of Natural History. Researchers from the United States Geological Survey and the Geological Society of America have used the unit to interpret Cenozoic climatic change and vertebrate evolution following the Eocene–Oligocene extinction event.

Geology and Stratigraphy

The Sharps Formation is lithologically characterized by siltstones, mudstones, sandstones, and paleosols that form part of the stratigraphic succession between the Chadron Formation and the Brule Formation. Regional mapping by the United States Geological Survey and stratigraphers affiliated with the University of Wyoming has refined correlations with the White River Formation framework used across the Great Plains. Lithofacies analysis by teams from the Geological Society of America and the American Association of Petroleum Geologists has documented lateral facies changes related to fluvial systems similar to those described in the Badlands National Park exposures. Biostratigraphic zones tied to mammalian assemblages recognized by specialists from the Carnegie Museum of Natural History and isotope stratigraphy work connected to laboratories at the University of California, Berkeley have constrained its position within the Oligocene.

Fossil assemblages from the Sharps Formation include rich vertebrate faunas studied by paleontologists at the American Museum of Natural History, Smithsonian Institution, and the Field Museum of Natural History. Important collections have been compared with material from the John Day Formation, the Brule Formation, and the Chadron Formation to interpret faunal turnover across the Oligocene. Notable taxa recovered by teams from the University of Nebraska State Museum and the Natural History Museum, London include artiodactyls and perissodactyls that inform evolutionary studies by researchers at the Royal Society and the Paleontological Society. Work by paleobotanists associated with Harvard University and the New York Botanical Garden has documented fossil leaves and seeds that complement mammalian data in paleoecological reconstructions presented at meetings of the Society of Vertebrate Paleontology.

Sedimentological studies led by investigators from the University of Kansas and the University of Missouri interpret the Sharps Formation as predominantly fluvial to overbank deposits, with paleosol horizons indicating episodic subaerial exposure comparable to depositional models used in the Florissant Fossil Beds National Monument research. Radiometric constraints and magnetostratigraphic correlations developed in collaboration with the Geological Society of America and laboratories at the University of Oxford place the unit within the Oligocene epoch, contemporaneous with faunal phases recognized by the International Commission on Stratigraphy. Paleoclimatic interpretations drawing on stable isotope work performed at the Scripps Institution of Oceanography and the Max Planck Institute for Chemistry suggest a cooling trend consistent with global patterns seen after the Eocene–Oligocene transition.

Although not a primary target for hydrocarbons in the manner of the Denver Basin or the Powder River Basin, the Sharps Formation has been assessed by the United States Geological Survey and the Bureau of Land Management for local groundwater aquifers and as a potential aggregate source for regional construction projects overseen by the South Dakota Department of Transportation. Mineral prospecting reports involving consultants from the American Geophysical Union and engineering firms working with the U.S. Army Corps of Engineers have evaluated its suitability as a building material and its geotechnical properties for infrastructure near the Badlands National Park roadways. Paleontological resources from the Sharps Formation also contribute to regional tourism associated with institutions such as the Black Hills Institute of Geological Research and museums in Rapid City, South Dakota.

Initial descriptions and mapping of the unit were advanced by field geologists from the United States Geological Survey and early 20th-century investigators connected to the University of Nebraska–Lincoln and the South Dakota School of Mines and Technology. Over the decades, major contributions have come from paleontologists at the American Museum of Natural History, the Smithsonian Institution, and the Carnegie Museum of Natural History, whose systematic collecting programs paralleled work at the John Day Fossil Beds National Monument. Key syntheses presented at conferences of the Geological Society of America and the Society of Vertebrate Paleontology integrated stratigraphic, paleontologic, and geochemical data produced by collaborative teams from the University of California, Los Angeles, Princeton University, and the University of Chicago.

Management of exposures and fossil localities within the Sharps Formation involves coordination among federal and state agencies such as the National Park Service, the Bureau of Land Management, the South Dakota Game, Fish and Parks Department, and municipal authorities in counties bordering Badlands National Park. Fossil stewardship policies informed by the Society of Vertebrate Paleontology and guidelines from the National Science Foundation govern collecting, curation, and public outreach carried out by museums including the Field Museum of Natural History and the University of Nebraska State Museum. Ongoing monitoring programs developed with the United States Geological Survey and conservation NGOs aim to balance paleontological research, educational access, and preservation of stratigraphic sections comparable to management practices at the Florissant Fossil Beds National Monument.

Category:Geologic formations of South Dakota