NPS Geodiversity Atlas—Hagerman Fossil Beds National Monument, Idaho

Geodiversity refers to the full variety of natural geologic (rocks, minerals, sediments, fossils, landforms, and physical processes) and soil resources and processes that occur in the park. A product of the Geologic Resources Inventory, the NPS Geodiversity Atlas delivers information in support of education, Geoconservation, and integrated management of living (biotic) and non-living (abiotic) components of the ecosystem.

hagerman fossil beds report cover with paleontologist image
In-depth geologic information is contained in the baseline inventory products of the Geologic Resources Inventory, see table below.

Geologic Features and Processes

Hagerman Fossil Beds National Monument is a world-renowned paleontological site based on the exceptional abundance and diversity of Pliocene fossils. The Hagerman horse (Equus simplicidens) is recognized as the official fossil for the state of Idaho. Over 550 fossil localities are documented on the arid slopes between the west bank of the Snake River and the Bruneau Plateau.

Hagerman Fossil Beds National Monument is located at the contact between the basalt-dominated Eastern Snake River Plain and the sediment-dominated Western Snake River Plain near the southeastern margin of ancient Lake Idaho. The general geology of the monument consists primarily of stream and lake sediments of the Pliocene Glenns Ferry, early Pleistocene Tuana Gravels, and Pleistocene Yahoo Clay of the Idaho Group. These formations lie unconformably on the siliceous Miocene-aged Idavada Volcanics. The Glenns Ferry Formation contains sediments inter-bedded with occasional basalt flows, silicic volcanic ash, and basaltic pyroclastic deposits, ranging in age from 1.8 - 3.5 million years old. The sediments represent deposition within lake, stream and flood plain environments.

Paleontological Resources

The Glenns Ferry Formation is the fossil producing unit at Hagerman Fossil Beds and represents a range of ancient terrestrial environments including wetland, riparian, lacustrine, and grassland savanna ecosystems. These unconsolidated sediments exposed within Hagerman Fossil Beds have yielded a remarkable diversity and abundance of fossils. Currently there are in excess of 500 known individual fossil localities within the monument, which have produced over 145 separate species of plants and animals, 44 of which are holotypes.

Data from Hagerman Fossil Beds also records the ecological response of various species and their environments to climate change during the Pliocene Paleontological research has been conducted in the Hagerman Fossil Beds area for more than half a century. An extensive body of literature related to the geology and paleontology of the area exists and is maintained by the park.

All NPS fossil resources are protected under the Paleontological Resources Preservation Act of 2009 (Public Law 111-11, Title VI, Subtitle D; 16 U.S.C. §§ 470aaa - 470aaa-11).


Landslides have been a problem for Hagerman Fossil Beds in the past. Causes seem to involve the amounts of water supplied by natural precipitation and by man-made irrigation. Irrigation has ceased since approximately 2005, but because of the steepness of the topography and the nature of the geologic materials, the potential still exists for future landslide events.

Radioactive geologic materials are known to exist at Hagerman Fossil Beds, both in the rocks and fossils. Uranium and radium are found in the basalt flows of the area and, in some cases, have been concentrated in fossil material. Radioactive materials pose a serious threat to human health and safety, so precautionary measures are needed while handling and preparing of some fossil material.

Geology Field Notes

Students and teachers of college-level (or AP) introductory geology or earth science teaching courses will find that each park's Geologic Resource Inventory report includes the Geologic History, Geologic Setting, and Geologic Features & Processes for the park which provides a useful summary of their overall geologic story. See Maps and Reports, below.

Regional Geology

Hagerman Fossil Beds is a part of the Columbia Plateau Physiographic Province and shares its geologic history and some characteristic geologic formations with a region that extends well beyond park boundaries.

Maps and Reports

The Geologic Resources Inventory produces digital geologic maps and reports for more than 270 natural resource parks. The products listed below are currently available for this park, check back often for updates as many maps, reports, and posters are still in progress.
  • Scoping summaries are records of scoping meetings where NPS staff and local geologists determined the park’s geologic mapping plan and what content should be included in the report.
  • Digital geologic maps include files for viewing in GIS software, a guide to using the data, and a document with ancillary map information. Newer products also include data viewable in Google Earth and online map services.
  • Reports use the maps to discuss the park’s setting and significance, notable geologic features and processes, geologic resource management issues, and geologic history.
  • Posters are a static view of the GIS data in PDF format. Newer posters include aerial imagery or shaded relief and other park information. They are also included with the reports.
  • Projects list basic information about the program and all products available for a park.

Source: Data Store Saved Search 2893. To search for additional information, visit the Data Store.

NPS Soil Resources Inventory project has been completed for Hagerman Fossil Beds National Monument and can be found on the NPS Data Store.

Source: Data Store Saved Search 2964. To search for additional information, visit the Data Store.

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Hagerman Fossil Beds National Monument

National Park Service Geodiversity Atlas

The servicewide Geodiversity Atlas provides information on geoheritage and geodiversity resources and values within the National Park System. This information supports science-based geoconservation and interpretation in the NPS, as well as STEM education in schools, museums, and field camps. The NPS Geologic Resources Division and many parks work with National and International geoconservation communities to ensure that NPS abiotic resources are managed using the highest standards and best practices available.

For more information on the NPS Geodiversity Atlas, contact us.

Hagerman Fossil Beds National Monument

Last updated: February 10, 2022