Sunset Crater is the youngest cinder cone of northern Arizona's San Francisco volcanic field. The Bonito slabby aa lava flow, shown here, erupted from the west base of the cone. The general absence of cinders on the flow suggests this occurred late in the eruptive life of Sunset Crater.
O'Leary Peak, an older volcanic dome, is in the background. Sunset Crater National Monument is a popular geotourism site.