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The Tertiary in Wyoming, US

Tertiary in Wyoming map

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Tertiary Fossils

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Paleontology and geology

Tertiary sediments are widespread in Wyoming, covering the floors of the Bighorn, Powder River, Wind River, and Green River Basins with thousands of feet of sediment eroded off the rising Rockies. The Early Tertiary climate favored the growth of luxurious forests that grew on the basin floors. The coals formed from these forests are mined in the state today, and fossil plants are common in many Tertiary formations. The Green River Formation, organic-rich rock referred to as oil shale, was deposited as sediment on the floor of an Early Tertiary (Eocene) lake that formed in the Green River Basin. These rocks contain abundant, beautifully preserved fish fossils, including the Wyoming State Fossil, Knightia eocaena, a herring-like fish. Less well known to most people are the fossils of flamingos, crocodiles, boas, and bats that have been found in the Green River shales. Large volcanic eruptions periodically deposited thick layers of ash across the state during the Middle Tertiary (Oligocene and Miocene), as the Rockies continued to rise.

Links to more on the Tertiary in Wyoming

Organizations | Education and Exhibits | Research and Collections | Resources


Parks (showing 1 of 1 listings)

Fossil Butte National Park: Designated a national park in 1972, Fossil Butte has preserved some of the most fossil-rich exposures of the Green River Formation for all to see. At this website, you can find information on the fossils and rocks in the park, as well as how to get there.

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Government Agencies (showing 1 of 1 listings)

Wyoming State Geological Survey: Find out more about the geological, paleontological, mineral, and energy resources of Wyoming. Maps and publications about Wyoming and the state's resources can be found for sale.

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Education and Exhibits

Virtual Exhibits (showing 1 of 1 listings)

Localities of the Eocene: The Green River Formation: Visit this exhibit for more information on the rocks, fossils, and history of research of the Green River Formation, including references. Explore other exhibits on the UC Museum of Paleontology site to find out about the Tertiary period and the animals that lived during that time.

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Research and Collections

Ongoing Research Projects (showing 1 of 1 listings)

Bridger Basin Project: Ongoing field research in the Bridger Formation of southwestern Wyoming seeks to document the stratigraphy and depositional environments of this highly fossiliferous middle Eocene rock unit, as well as the biostratigraphy, biochronology, and evolutionary relationships of its abundant and exquisitely preserved fossils.

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Field Guides (showing 1 of 1 listings)

Green River Paleobotany Project: This site is geared towards amateurs and professionals who collect fossil plants from the Parachute Creek Member of the Green River Formation in Colorado and Utah. The site provides an identification guide for more than 250 species of fossil plants and encourages collectors to submit images of their own fossils if they think they have found a new species.

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