Engulfed in summer's heat, it's good to remember that autumn is not so far off. Here the quaking aspen of the Inner Basin of the Pleistocene San Francisco Mountain are in full fall bloom. San Francisco Mountain is a large composite volcano of the San Francisco Volcanic field of northern Arizona. The inner crater formed during a catastrophic debris avalanche event that decapitated the summit and delivered debris avalanche materials to the plain east of San Francisco Mountain. Photo by Ted Grussing.