Hagerman Fossil Beds National Monument, in Idaho, is most famous for the Hagerman Horse, which is also the state fossil. The monument is significant for its variety, quantity, and quality of animal and plant fossils.
What the Scientists Found Here
No other fossil beds preserve such varied land and aquatic species from the time period called the Pliocene Epoch. Over 200 species of plants and animals have been found at hundreds of sites in this park. Eight species are found only here, and 43 were found here first. The Hagerman horse, Equus simplicidens, typifies the fossil quality. Complete and partial skeletons of this zebra-like ancestor of today's horse have come from these fossil beds.
Paleontologists from the Smithsonian Institution in Washington, DC, made the first scientific excavations here in 1929. Local rancher Elmer Cook had shown the fossil beds to a government geologist, Dr. Harold Stearns. During the 1930s, the Smithsonian scientists excavated 120 horse skulls and 20 complete skeletons from an area now called the Horse Quarry. The Smithsonian exchanged some Hagerman horse skeletons with other museums, resulting in their display around the world. Other museums, universities, and the National Park Service have now done work here. Over 200 scientific papers now focus on the Hagerman fossil species.
Clues in the Landscape
Bluffs that contain Hagerman Fossil Beds rise 600 feet above the Snake River. They reveal the environment at the end of the Pliocene Epoch. Grassy plains with ponds and forest stands then received over twice today's 7-10 inches of annual precipitation. Saber-toothed cats, mastodons, camels, ground sloths, hyena-like dogs, beavers, muskrats, otters, antelope, deer, fish, frogs, snakes, and waterfowl lived then.
Sediment layers from river to bluff tops span 550,000 years: 3.7 million years old at river level to 3.15 million years atop the bluff. The layers were deposited when rivers flowing into ancient Lake Idaho flooded the area. The Bonneville Flood 15,000 years ago carved the high bluffs, exposing the layers and fossils. It also deposited fields of melon gravellava boulders the size of watermelons and largerfrom today's river level to gravel bars 225 feet higher. Sediments include river sands, shale deposited in ponds, clay from floods, and volcanic deposits like ash and basalt. Radioactive elements in volcanic ashes are used to determine a fossil's age.
Adapt, Migrate, or Become Extinct
As significant environmental change happens, most plants and animals will have three options: adapt, migrate, or become extinct. The ancient ecosystem of Hagerman's fossil plants and animals shows each response as the area changed from a wetter grassland savanna to today's drier high-desert conditions.
Hagerman Fossil Beds is one of the few sites that preserve enough variety and quantity of fossil evidence to study past climates and ancient ecosystems. Fossil studies also add to research on biodiversity, wetlands ecology, and evolutionary patterns.
Epochs of the CENOZOIC
Indians, Emigrants, and Farmers
American Indians now known as the Shoshone-Bannocks and the Shoshone-Paiutes have lived in the Hagerman Valley for 12,000 years. They caught and dried salmon, steelhead trout, whitefish, and other fishincluding sturgeon weighing over 1,500 pounds. They dug camas lily and other roots and harvested seeds, fruits, and other plants. They hunted small animals and deer, elk, and mountain sheep.
Well-preserved segments of the Oregon Trail exist in the southern part of the monument. Intense summer heat, dust, wind, and lack of water made crossing the Snake River Plain an ordeal. The Hagerman Valley was one of the few places where emigrants could reach the Snake River for water and to trade for fish with American Indians. Another 700 miles of arduous travel lay between here and their destination.
In 1862, the Idaho gold rush increased traffic on the Oregon Trail. Trains of freight wagons hauling up to five tons each brought supplies to Army camps, mines, and developing towns. A few ranchers settled here later. Farming began in the valley in 1879, with John Bell growing alfalfa. In 1882, the Oregon Short Line railroad arrived north of the valley, and farming settlement increased. Today's farmers grow corn and potatoes as the major crops.
Bounded on the east by basalt cliffs formed from past lava flows, the valley boasts many springs. Their water exits the ground at a consistent temperature that is ideal for raising trout. Because the springs also keep the wetlands from freezing in winter, many migrating waterfowl spend the winter here.
Visiting the National Monument
The visitor center is across from the high school on US 30 (221 N. State Street). It offers information, exhibits, displays, and a bookstore. Open 9 to 5 seasonally; call ahead or check the park website for the schedule. Ranger-led programs are listed on the website.
To reach overlooks, drive south on US 30 and cross the Snake River on the Gridley Island Bridge. Turn right on Bell Rapids Road and drive 2.8 miles. The Snake River Overlook is on the right, 0.10 mile after you enter the monument. The boardwalk has exhibits and provides a view of the fossil beds and Snake River. Cross the road to an exhibit about the Oregon Trail; follow the path to see the famous trail.
Continue up the road for three miles to reach the Oregon Trail Overlook. Walk the half-mile interpretive trail to enjoy commanding views. You can also start the Emigrant Trail here. This three-mile trail parallels the Oregon Trail.
Regulations and Safety
For firearms regulations, check the park website.
All natural and historic features are protected by federal law. Do not take, disturb, or damage any fossil. If you find a fossil, leave it in place and report it to a ranger. Many fossils are fragile and must be protected by trained experts before they can be moved safely.
Emergencies call 911
Source: NPS Brochure (2014)
Brochures ◆ Site Bulletins ◆ Trading Cards
A Study of the Fossil Horse Remains from the Upper Pliocene of Idaho (C. Lewis Gazin, extract from Proceedings of the United States National Museum, Vol. 83 No. 2985, 1936)
A Traditional Use Study of the Hagerman Fossil Beds National Monument and Other Areas in Southern Idaho (L. Daniel Myers, September 1998)
An Ethnographic Overview and Assessment of the Hagerman Fossil Beds National Monument and Other Area in Southern Idaho (L. Daniel Myers, August 1999)
Fossil Hares from the Late Pliocene of Southern Idaho (C. Lewis Gazin, extract from Proceedings of the United States National Museum, Vol. 83 No. 2976, 1934)
Fossil peccary remains from the upper Pliocene of Idaho (C. Lewis Gazin, extract from Journal of the Washington Academy of Sciences, Vol. 28 No. 2, February 15, 1938)
Geologic Resources Inventory Report, Hagerman Fossil Beds National Monument NPS Natural Resource Report NPS/NRPC/GRD/NRR-2009/162 (J. Graham, December 2009)
Groundwater evaluation of geologic hazards at the Hagerman Fossil Beds, Twin Falls County, Idaho (Paul Summers, December 1985)
Historical Overview: Upper Salmon Falls to Lower Salmon Falls (Todd Shallatt, Kathryn Baxter, Kelly Murphey and Ron James, December 2000)
History of Snake River Canyon Indicated by Revised Stratigraphy of Snake River Group Near Hagerman and King Hill, Idaho USGS Professional Paper 644-F (Harold E. Malde and Allan Cox, 1971)
Late Pliocene (Blancan) Scapanus (Scapanus) (Tilpidae: Mammalia) from the Glenns Ferry Formation of Idaho (J. Howard Hutchison, extract from PaleoBios, Vol. 12 No. 45, 1987)
Long-Range Interpretive Plan: Hagerman Fossil Beds National Monument (September 2016)
Monitoring Sagebrush-steppe Vegetation in the Upper Columbia Basin Network, 2008 Annual Monitoring Report, City of Rocks National Reserve, Hagerman Fossil Beds National Monument, John Day Fossil Beds National Monument NPS Natural Resource Technical Report NPS/UCBN/NRTR-2009/182 (Thomas J. Rodhouse, March 2009)
Museum Management Plan: City of Rocks National Reserve, Craters of the Moon National Monument and Preserve, Hagerman Fossil Beds National Monument, Minidoka Internment National Monument (Robert Applegate, Kent Bush, Brooke Childrey, H. Dale Durham, Phil Gensler, Kirstie Haertel and Diane Nicholson, 2008)
Natural Resource Condition Assessment, Hagerman Fossil Beds National Monument NPS Natural Resource Report NPS/UCBN/NRR-2012/599 (Mark V. Corrao and John A. Erixson, December 2012)
Pearce's Peccary Platygonus pearcei (Greg McDonald, c1993)
Paleontological Resource Inventory and Monitoring, Upper Columbia Basin Network NPS TIC# D-259 (Jason P. Kenworthy, Vincent L. Santucci, Michaleen McNerny and Kathryn Snell, August 2005)
Results of a three-year paleontology inventory at Hagerman Fossil Beds National Monument, southern Idaho (Phil Gensler and Mary C. Carpenter, New Mexico Museum of Natural History & Science Bulletin 34, 2006, ©New Mexico Museum of Natural History and Science, all rights reserved)
Sagebrush Steppe Vegetation Monitoring in Craters of the Moon National Monument and Preserve, Hagerman Fossil Beds National Monument, John Day Fossil Beds National Monument, and Lake Roosevelt National Recreation Area: 2009 Annual Report NPS Natural Resource Technical Report NPS/UCBN/NRTR-2010/302 (Thomas J. Rodhouse, March 2010)
Sagebrush Steppe Vegetation Monitoring in Hagerman Fossil Beds National Monument, 2012 Annual Report NPS Natural Resource Report NPS/UCBN/NRDS-2012/402 (Devin S. Stucki and Thomas J. Rodhouse, October 2012)
Sagebrush Steppe Vegetation Monitoring in Hagerman Fossil Beds National Monument, 2018 Annual Report NPS Natural Resource Report NPS/UCBN/NRR-2019/1870 (Melissa M. Nicolli, February 2019)
Stratigraphy of the Glenns Ferry Formation from Hammett to Hagerman, Idaho Geological Survey Bulletin 1331-D (Harold E. Malde, 1972)
The Fossil Record (1993-2005)
The Hagerman Horse Quarry: History, Status, Potential, and Recommendations for the Future Idaho Museum of Natural History Paleontology Report #2 (William A. Akersten and Mary E. Thompson, December 1992)
The Insectivores of the Hagerman Local Fauna, Upper Pliocene of Idaho (Claude W. Hibbard and Philip R. Bjork, extract from Contributions from the Museum of Paleontology, The University of Michigan Vol. 23 No. 9, February 22, 1971)
The Rodents from the Hagerman Local Fauna, Upper Pliocene of Idaho (Richard J. Zakrzewski, extract from Contributions from the Museum of Paleontology, The University of Michigan Vol. 23 No. 1, November 28, 1969)
Water Resources Management Plan, Hagerman Fossil Beds National Monument, Idaho (Neal Farmer and Jon Riedel, February 2003)
Handbooks ◆ Books
Last Updated: 31-May-2022