Barnes Butte, a volcanic rhyolite dome of welded tuff on the edge of Prineville, is part of the Crooked River caldera and a prominent local landmark. Partly within the city, it also bears traces of a more recent industrial era: a mercury mine operated there in the 1940s, and in 2015 the Bureau of Land Management conducted cleanup work to reduce health risks for nearby residents and Barnes Butte Elementary School. Today the butte is valued mainly for recreation, scenery, and preservation, with hiking trails and a city-adopted 2021 concept plan proposing future amenities and habitat improvements around Happy Hour Plateau.