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Surficial geology of the Southwest Principal Aquifers (SWPA) study

Published by U.S. Geological Survey | Department of the Interior | Metadata Last Checked: February 10, 2026 | Last Modified: 2020-11-17T00:00:00Z
This is a 100-meter cell resolution raster dataset consisting of 1:750,000-scale surficial geology for California and 1:500,000-scale for Nevada, and parts of Utah, Colorado, New Mexico, and Arizona. This data set was aggregated from a compilation of geologic maps of the Southwest Regional GAP Analysis Project (ReGAP) along with California geology and the very southern portion of Oregon and Idaho geology.

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