This eruption ejected layers of rhyolite and produced tuff, creating formations of rock in the Leslie Gulch.

Nearby features include the Owyhee River, historically used as a fishing and camping ground for early Native Americans.

[3][verification needed] The caldera is narrow and shaped like a ridge, with precipitous slopes and an escarpment on the northwest flank.

[5] The gulch features an array of rock formations and ash erupted from the volcano approximately 15.5 million years ago.

[6] The nearby Owyhee River was utilized by Native Americans as early as 5,000 years before European habitation of the area.