The Geology of Crater Lake National Park, Oregon With a reconnaissance of the Cascade Range southward to Mount Shasta by Howell Williams
The Parasitic Scoria Cones of Mount Mazama
The Younger Cones
This cone rises approximately 600 feet above a pedestal of glaciated, olivine-rich basaltic andesite and basalt. The greater part is composed of basaltic scoria, among which may be found occasional ribbon bombs 5 feet in length. Close to the summit there are several flows of basalt, and probably others are concealed by slides of scoria. The cone is thus composite. Mixed with the scoria are angular lithic fragments torn from the basement. The summit crater is represented only by irregular depressions, but the flanks of the cone have scarcely been modified by erosion.