It is underlain by a basement terrane comprising Proterozoic metamorphic rocks, Mesozoic plutonic rocks, and Mesozoic and Mesozoic or Cenozoic hypabyssal dikes. The basement terrane is capped by a widespread Tertiary erosion surface preserved in remnants in the Eagle Mountains and buried beneath Cenozoic deposits in Pinto Basin. In adjacent quadrangles, Miocene basalt overlies the erosion surface. A sequence of at least three Quaternary pediments is planed into the north piedmont of the Eagle Mountains, each in turn overlain by successively younger residual and alluvial deposits. File Size Readme tabulates contents of database and describes how to access them.
Metadata file contains detailed technical descriptions of structure and content of digital data.
Also available on the USGS Geologic Division Node of the National Geospatial Data Clearinghouse in these two and other formats. Explanatory pamphlet describes approach used in building database, and discusses purpose, content, and geologic framework of database. Portable Document Format file containing full-sized, navigable graphic image of geologic map with marginal explanation.