Geologic Map and Report for the Theodore Roosevelt Dam Area, Gila and Maricopa Counties, Arizona

The Theodore Roosevelt Dam area is located approximately 90 km east of Phoenix on the southwest flank of Tonto Basin (Figure 1). The map area encompasses the southeastern end of the Mazatzal Mountains and the northern Two Bar Ridge area at the northeastern end of the Superstition Mountains. The area was mapped during November, 1997 to April, 1998, as part of a multiyear mapping program directed at producing a geologic map of the Theodore Roosevelt 30' x 60' Quadrangle. A 1 :24,000 scale map is the primary product of this study (Plate 1; Figure 2), and the accompanying report describes rock units and other geologic features and includes modal mineral analyses of granitic rocks that was done in order to classify the granitoids.