Geologic map of Gray Mountain and Painted Desert, northern Arizona, by George Billingsley and others (US. Geological Survey). Gray Mountain is one of a number of prominent monoclines on Arizona's Colorado Plateau.
Billingsley, G.H., Priest, S.S., and Felger, T.J, 2007, Geologic map of the Cameron 30' x 60' quadrangle, Coconino County, northern Arizona. U.S. Geological Survey Scientific Investigations Map SIM-2977, map scale 1:100,000. ngmdb.usgs.gov/Prodesc/proddesc_93280.htm