Geology of Cemetery Ridge, Clanton Hills, and Westernmost Gila Bend Mountains, La Paz and Yuma Counties, Arizona

The area described in this study includes Cemetery Ridge, the Clanton Hills, and the westernmost Gila Bend Mountains (picacho Hills), La paz and Yuma counties, Arizona. The study area (Fig. 1) encompasses all of the Nottbusch Butte Quadrangle (1:24,000), the northern part of the Turtleback Mountain Quadrangle (1 :24,000), and the southwestern part of the Eagletail Mountains West Quadrangle (1 :24,000). Bedrock in this area consists of Proterozoic to Jurassic igneous and metamorphic rocks that are overlain by Miocene silicic volcanic rocks, subordinate mafic and intermediate volcanic units, and continental calcareous sedimentary rocks (plate 1). Sources of data are shown in Figure 2, rock-unit correlations and relative ages are shown in Figure 3, and map symbols are shown in Table 1. The area was mapped with funds provided to the Arizona Geological Survey by the U.S. Geological Survey COGEOMAP program, contract #14-08-0001-A0872. Field work was carried out in November"' and December, 1991. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government.