The Mount Fagan quadrangle is located approximately 30 km southeast of downtown Tucson, and includes the northern terminus of two mountain ranges; of the Santa Rita Mountains in the center and southwest, and the Empire Mountains along the eastern boundary. The northern portion of the quadrangle consists of a gently north-sloping piedmont surface carved into Quaternary basin-fill deposits in the northwest and rolling hills of bedrock in the northeast (Figure 1). The area was mapped during October, 2000 through May, 2001 as part of a multiyear mapping program directed at producing complete geologic map coverage for the Phoenix-Tucson metropolitan corridor. A 1:24,000 scale map is the primary product of this study (Plate 1). Mapping was done under the joint State-Federal STATEMAP program, as specified in the National Geologic Mapping Act of 1992, and was jointly funded by the Arizona Geological Survey and the U.S. Geological Survey under STATEMAP Program Contract #00HQAG0149.