Excellent exposure of the Miocene Peach Spring Tuff in contact with a sandstone and capped by a thick petrocalcic (hardpan) breccia unit. The Peach Spring Tuff accompanied the formation of the Silver Creek Caldera about 18.8 Ma.
For more, see AZGS's Charles Ferguson's 29-page field trip guide, "The Peach Spring Tuff, its source caldera, and implications for structural geology of the Colorado River Extensional Corridor". http://repository.azgs.az.gov/uri_gin/azgs/dlio/1878
