The park is rich in geological history. Volcanic evidence is everywhere. The Devil's Gate Pass is all that remains of an extinct volcano.

The prehistoric Bonneville Flood shaped the landscape of the area, rolling and polishing the huge boulders found throughout the park. The flood was caused when eroding waters broke through Red Rock Pass near the Idaho/Utah border. Lake Bonneville, which covered much of what is today the state of Utah, surged through the pass and along the channel of the Snake River in a few short months. For a time, the flow was four times that of the Amazon River. It was the second largest

flood in the geologic history of the world.