Hagerman Fossil Beds National Monument

One of North America's richest Pliocene fossil sites, where a rancher found hundreds of prehistoric horses

The Hagerman Fossil Beds cover 4,300 acres of Snake River Canyon and hold one of the most significant Pliocene-era fossil deposits in North America. The star exhibit is the Hagerman Horse, a primitive relative of the modern horse that lived about 3.5 million years ago. Over 200 individual horse specimens have been found here, more than anywhere else on Earth, along with fossils of mastodons, giant ground sloths, American camels, and early forms of beaver and otter.

The visitor centre in town has replicas and interpretation; the actual fossil beds are out on the canyon edge, accessible by a short drive and walk. The site overlooks the Snake River from a sagebrush bluff with good views across the canyon. Guided geology walks run seasonally. The monument itself has no entrance fee.

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A story
In 1928 rancher Elias Hughes noticed some large bones eroding out of the canyon wall on his property. He reported them to the Smithsonian, which excavated over 200 individual specimens of what became known as Hagerman Horse — closely related to the modern horse but extinct for 3.5 million years. The site is now the richest known deposit of Pliocene horse fossils in the world, and the Hagerman Horse (*Equus simplicidens*) is the official state fossil of Idaho.

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