Description

This map and report summarize the surficial geology of the southern parts of the New River Mesa and Humboldt Mountain quadrangles on the northeastern margin of the Phoenix metropolitan area. The map area is just north of Cave Creek and Carefree and is approximately 40 km northeast of Phoenix. The map area consists primarily of fairly rugged mountainous terrain, but also includes the valleys of Cave Creek and Camp Creek and the northern part of an extensive dissected bedrock pediment. The mountainous portion of the study area is underlain by Precambrian metamorphic and granitic rocks, and Tertiary basalt and sedimentary rocks. Most of the bedrock at the surface in the mountains has been weathered into hillslope colluvium, although relatively intact bedrock may be observed in gullies. Deeply weathered Precambrian granitic rocks have been eroded into a well-developed pediment at the southern margin of the mapped area. Quaternary alluvium is found primarily along the larger drainage's in the mountains and along smaller drainage's that cross the pedimented areas on the southern margin of the map area.