Bear River Formation

Bear River Formation
Name	Bear River Formation
Type	Formation
Period	Paleogene
Namedfor	Bear River
Region	Western North America
Country	United States

Bear River Formation The Bear River Formation is a sedimentary rock unit known from exposures in parts of western North America. It has been the focus of regional studies in stratigraphy and paleontology, and has been sampled by researchers from institutions such as the Smithsonian Institution, United States Geological Survey, University of California, and University of Wyoming. Work on the unit intersects with regional syntheses like the Geologic Map of North America and surveys by the American Association of Petroleum Geologists.

Description and Geology

The Bear River Formation consists principally of sedimentary lithologies that include sandstone, siltstone, shale, and interbedded conglomerate, and its outcrops crop out in upland areas adjacent to basins mapped by the United States Geological Survey, the Geological Society of America, and regional surveys from the California Geological Survey. Lithofacies analysis follows methods employed by researchers from the University of Colorado and the University of Utah, and comparisons are made with coeval units such as the Wasatch Formation and the Green River Formation. Structural context includes deformation related to the Laramide Orogeny and later Basin and Range extension described in syntheses appearing in journals like the Journal of Geology and publications of the Royal Society.

Stratigraphy and Age

Biostratigraphic, magnetostratigraphic, and radiometric constraints place parts of the formation in the Paleogene, with correlations to stages defined by the International Commission on Stratigraphy. Key chronostratigraphic markers used in correlation have been reported by teams from the Geological Society of America and cross-referenced against global timescales maintained by the International Union of Geological Sciences. The formation is mapped in stratigraphic columns alongside units such as the Eocene Green River Formation and the Oligocene White River Formation, and its age determinations have been discussed at meetings of the American Geophysical Union and in reports from the U.S. Bureau of Mines.

Paleontology

Fossil content reported from the Bear River Formation includes floral and faunal assemblages that have been compared with collections curated by the Smithsonian Institution, the Natural History Museum, London, and major university museums such as the American Museum of Natural History. Vertebrate remains attributed to Paleogene mammal groups have been described in publications associated with the Society of Vertebrate Paleontology and compared with taxa from the Eocene Wasatch Formation and faunas cataloged at the Yale Peabody Museum of Natural History. Plant macrofossils and palynological assemblages have been used in climate reconstructions following protocols from the Botanical Society of America and studies appearing in journals like Palaeogeography, Palaeoclimatology, Palaeoecology. Trace fossils and invertebrate assemblages have been referenced against regional faunas preserved in units such as the Green River Formation and collections at the Field Museum of Natural History.

Depositional Environment and Paleoclimate

Sedimentological and paleobotanical evidence has been interpreted in the context of depositional models advanced by investigators from the University of British Columbia and the University of Texas at Austin, invoking fluvial, lacustrine, and overbank settings with episodic high-energy input likely linked to regional tectonics including the Laramide Orogeny and subsequent Basin and Range Province extension. Paleoclimate reconstructions draw on analogues discussed at forums like the American Meteorological Society and papers in the Journal of Paleolimnology, and comparisons have been made with Eocene greenhouse intervals summarized by the Intergovernmental Panel on Climate Change and paleobotanical compilations in the Royal Society Open Science.

Economic Importance and Resource Uses

The Bear River Formation has been evaluated for resources by the United States Geological Survey and energy companies represented in publications of the Society of Petroleum Engineers. Prospecting has assessed potential for reservoir-quality sandstones, source-rock potential in organic-rich shales, and aggregate for the construction industry as documented in state geological survey reports such as those from the California Geological Survey and the Wyoming State Geological Survey. Regional mineral assessments have been coordinated with agencies including the U.S. Bureau of Land Management and analyses have appeared in proceedings of the American Association of Petroleum Geologists.

History of Research and Naming

The unit was first recognized and named during geological mapping campaigns led by state geological surveys and field parties connected to institutions such as the United States Geological Survey and the University of Utah. Early descriptions were published in bulletins and geological survey maps comparable to those produced by the Geological Survey of Canada and were later revised in monographs and regional syntheses appearing in venues like the Geological Society of America Bulletin and archives of the Smithsonian Institution. Ongoing work continues through collaborations between academic groups at the University of California, the University of Wyoming, and federal agencies including the United States Geological Survey.

Category:Geologic formations of North America