Hopkins, R.L., and Ranney W.D., 1987, Geology of the Grand Canyon - A hike through time, in Davis, G.H., and VandenDolder, E.M., eds., Geologic diversity of Arizona and its margins: Excursions to choice areas; Field-trip guidebook, 100th Annual Meeting, The Geological Society of America, Phoenix, Arizona, October 26-29, 1987: Arizona Bureau of Geology and Mineral Technology Special Paper 5, p. 52.
