The fall of ash drifted downwind from the Bruneau-Jarbidge supervolcano eruption (in present-day Idaho), nearly 1,000 miles (1,600 km) west of the Ashfall site.

A large number of very well preserved fossil Teleoceras (extinct hippo-like relatives of rhinos), small three-toed and one-toed horses, camels, and birds have been excavated.

There are also abundant clues to the region's ecology, indicating a savanna of grassland interspersed with trees that luxuriated in a warmer, milder climate than today's.

The rapidly accumulating ash, windblown into deep drifts at low places like the waterhole site, remained moderately soft.

[10] Specially constructed walkways afford visitors an unobstructed close-up view of paleontologists at work during the summer field season.