Geologic Map of the Cocoraque Butte 7.5' Quadrangle, Pima County, Arizona, v. 2.0

The rocks exposed in this study area represent the eastern-most exposures of the Roskruge Mountains, themselves part of a long chain of low ridges and hills extending as far north as the Silverbell Mountains, and as far south as the Coyote Mountains. This part of the Roskruge Mountains contains rocks that can be grouped into three major subdivisions as follows: (1) a sequence of steeply tilted and folded sedimentary and volcanic rocks containing andesite, rhyolite, and both fluvial and eolian sandstones, (2) a thick pile of Cretaceous rhyodacitic welded ash-flow tuff—here containing only the Tuff of Sharp Peak, and (3) much younger middle Tertiary volcanic and sedimentary rocks. A small granitic pluton intrudes rocks of subdivision [...]