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The Greenback Creek 7 ½’ Quadrangle is located on the west flank of the Sierra Ancha and directly northeast of Theodore Roosevelt Lake (Figure 1). The geology is dominated by sedimentary rocks of the middle Proterozoic Apache Group and the middle Proterozoic diabase that commonly intrudes it (e.g. Bergquist et al., 1981; Wrucke, 1989). Early to middle Proterozoic granitic rocks are exposed beneath the Apache Group, primarily along the southwestern edge of the bedrock exposures in the map area. Tertiary conglomerate and local sandstone are deposited on the bedrock and in the flanking Tonto Basin, and have been subjected to only minor faulting and tilting. Upper Cenozoic sedimentary units and geomorphic surfaces were...
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The New River Mesa Quadrangle is located along the northern fringe of the Phoenix metropolitan area. The quadrangle includes several high-standing mesas, and although the rugged terrain of the New River Mesa area is undeveloped, the area to the south is becoming increasingly urbanized and is undergoing rapid population growth. Geologic mapping was related to other previous and ongoing mapping projects of urban fringe areas located to the north and northeast of the Phoenix metropolitan area. A series of color 1 : 24,000-scale aerial photographs (dated 11-5-79 and 6-11-88) were obtained from the U. S. Department of Interior and the Tonto National Forest office in Phoenix, and these were used by the field geologists...
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