Autumn 2016 in the San Francisco volcanic field of northern Arizona. In the foreground is the reddish summit of Sunset Crater, at about 960 years old, the youngest cinder cone in the field. To its right is O'Leary Peak a dacitic dome complex. Look carefully and you can the 4-wheel drive track leading to the fire tower at the summit of O'Leary Peak. In the background, and almost free of clouds, is the late Pleistocene San Francisco Mountain (Peaks). The ribbons of yellow are groves of quaking aspen trees whose leaves have gone from green to yellow with the cooler fall weather. There a number of excellent online resources describing the volcanism of the San Francisco volcanic field.
Here are several to start with: Hanson, S.L., 2003, Roadside Geology: Wupatki and Sunset Crater Volcano National Monuments. (36 pages) https://library.azgs.arizona.edu/item/DTES-1552427813305-598
Bezy, J.V., 2003, A Guide to the Geology of the Flagstaff Area (56 pages) https://library.azgs.arizona.edu/item/DTES-1552427824089-899
Richard Holm, 1988, Geologic map of San Francisco Mountain, Elden Mountain, and Dry Lake Hills, Coconino County, Arizona. https://ngmdb.usgs.gov/Prodesc/proddesc_9878.htm
Photographer: Ted Grussing
Photo Date: 2016