Red Mountain crops out on the west-central side of the 5,000 sq. kilometer San Francisco volcanic field of northern Arizona. A late stage phreatomagmatic blast carved out an amphitheater in cones interior. The interior cinder cone stratigraphy is beautifully exposed. Large xenocrysts of pyroxene (augite) are abundant in the walls and floor of the crater.
Photographer: Ted Grussing
Photo Date: September 2017