The geologic map of the 7.5' quad of Needles has been published by the USGS and various versions are available online.
The announcement says "The quadrangle is underlain by structurally undeformed sediments of Pliocene and younger age that were deposited by the Colorado River, as well as alluvial fan deposits on the piedmonts that flank the Black Mountains (in Arizona) and the Sacramento Mountains (in California)."
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