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U.S. Geological Survey Scientific Investigations Map 3062

Geologic Map of the Needles 7.5’ Quadrangle, California and Arizona

By Daniel V. Malmon, Keith A. Howard, and Susan S. Priest

2009

Abstract

Thumbnail of and link to map PDF (41 MB)

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.

Version 1.0

Posted March 2, 2009

For additional information:
Contact Information, Western Region Geology and Geophysics Science Center—Menlo Park
U.S. Geological Survey
345 Middlefield Road, MS-975
Menlo Park, CA 94025-3591
http://geomaps.wr.usgs.gov/

This report is available via print on demand.

Part of this report is presented in Portable Document Format (PDF). Download the latest version of Adobe Reader, free of charge.


Suggested citation:

Malmon, Daniel V., Howard, Keith A., and Priest, Susan S., 2009, Geologic map of the Needles 7.5' quadrangle, California and Arizona: U.S. Geological Survey Scientific Investigations Map 3062, scale 1;24,000, 1 sheet, includes 31 p. pamphlet [https://pubs.usgs.gov/sim/3062/].



Contents of pamphlet

Introduction

Methods

Age Designations

Stratigraphic Nomenclature and Mapping Conventions

Geologic and Tectonic Setting

Geologic History and Interpretations

Exposure at the Southpoint Power Plant

Distribution of Sediment on the Valley Floor

Flood Hazards in the Needles Quadrangle

Acknowledgments

Description of Map Units

References Cited


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