Big Southern Butte is one of two rhyolitic domes rising from a sea of basalt near the center of the eastern Snake River Plain. Big Southern Butte is one of the largest volcanic domes in the world but at 300,000 years old is also one of the youngest. Access to the top of the butte is available by a Bureau of Land Management service road.   Hikers who trek to the 7,550-foot high summit are rewarded with spectacular panoramic views.
Of the nearby Twin Buttes, East Butte is rhyolitic and Middle Butte is basaltic.
This is the official Idaho Historical Markers Map by the Idaho Transportation Department.
This is the official Idaho Rest Area Map by the Idaho Transportation Department.

Big Southern Butte is one of two rhyolitic domes rising from a sea of basalt near the center of the eastern Snake River Plain. Big Southern Butte is one of the largest volcanic domes in the world but at 300,000 years old is also one of the youngest. Access to the top of the butte is available by a Bureau of Land Management service road.   Hikers who trek to the 7,550-foot high summit are rewarded with spectacular panoramic views.
Of the nearby Twin Buttes, East Butte is rhyolitic and Middle Butte is basaltic.
This is the official Idaho Historical Markers Map by the Idah...