Geological Map of the Galleta Flat East 7.5' Quadrangle, Cochise County, Arizona, v. 3.0

The Galleta Flat East 7.5' Quadrangle is located in northwestern Cochise County in southeastern Arizona, north of the town of Benson. The San Pedro River flows south to north across the quadrangle and has been in a downcutting phase during the Quaternary. Lower Quaternary and upper Pliocene strata, which are exposed in bluffs and low hills flanking the river, were deposited in fluvial and lacustrine-margin to playa environments (Smith, 1994; Youberg et al., 2003). Bedrock exposed near the northern end of the Quadrangle consists of early Proterozoic Johnny Lyon Granodiorite and Pinal Schist (Cooper and Silver, 1964; Drewes, 1974).