Geologic Map of the Needles 7.5' quadrangle, California and Arizona

Scientific Investigations Map 3062
By: , and 



The Needles 7.5' quadrangle straddles the Colorado River in the southern part of the Mohave Valley, in Mohave County, Arizona, and San Bernardino County, California. The quadrangle contains part of the Havasu National Wildlife Refuge, sections of the Fort Mojave Indian Reservation, most of the city of Needles, and several major interstate highways and railroads. 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). Multiple cycles of aggradation of the Colorado River, each followed by episodes of downcutting, are recorded by Pliocene through historic deposits on the piedmonts that border the floodplain. Regionally, the complex stratigraphy related to the Colorado River has been the subject of geologic interest for over 150 years. The California and Arizona piedmont portions of the Needles quadrangle expose a subset of this incompletely understood stratigraphic record. Thus, the stratigraphic sequence presented on this map is a version of the stratigraphy of the Colorado River as interpreted locally. The deposits in the recently active Colorado River valley floor support riparian habitat and irrigated agriculture. The distributions of sand-rich channel deposits and mud-rich floodplain deposits in the valley are mapped on the basis of the history of the movement of the Colorado River in the quadrangle, which has been documented in sequential aerial photographs since 1937 and maps dating to 1857.

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Geologic Map of the Needles 7.5' quadrangle, California and Arizona
Series title Scientific Investigations Map
Series number 3062
DOI 10.3133/sim3062
Edition Version 1.0
Year Published 2009
Language English
Publisher U.S. Geological Survey
Contributing office(s) Western Earth Surface Processes
Description Report: ii, 31 p.; Map: 37 x 29.5 inches; Image; ReadMe; Metadata; Geodatabase; Shapefiles
Country United States
State Arizona, California
Other Geospatial Needles 7.5' quadrangle
Projection Polyconic
Scale 24000
Online Only (Y/N) N
Additional Online Files (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details