Geologic Map of the North of Oracle 7.5' Quadrangle, Southeastern Pinal County, Arizona, v. 2.0

The North of Oracle 7½' Quadrangle is located in southeastern Pinal County about 30 miles north of Tucson, Arizona, and lies north and northwest of the town of Oracle. The northeastern corner of the map area encompasses a portion of the western flank of the Black Hills. Signal Peak is just out of the map area in the adjacent Mammoth 7½' Quadrangle to the east. The southeast corner of the map area includes the northern outskirts of the town of Oracle and the large Tucson Wash drainage. The dominant physiographic feature in the map area, however, is Camp Grant Wash, the major drainage for the basin between the Black Hills and Black Mountains, which cuts through the northern part of the map area as it drains northeast to the San Pedro River. The maximum elevation in the map area is about 4400 feet in the southwest corner, and the minimum elevation is about 3200 feet where Camp Grant Wash exits the map area to the north. Bedrock and surficial geology in the study area were mapped between October 2001 to June 2002 as part of a multiyear mapping program directed at producing complete geologic map coverage for the Phoenix-Tucson metropolitan corridor. Additional bedrock mapping, done by J. Spencer in 2003, outlined an extensive pediment developed on porphyritic granite near the center of the south edge of the map. This map is designated version 2.0, with a new publication date, because of this new mapping. Purpose: Geologic mapping north of Tucson is part of continuing efforts by the AZGS to map the geology of the Phoenix - Tucson urban corridor. This map builds on and complements previous and concurrent surfical geologic mapping efforts in the Tucson area.