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Age, distribution, and formation of late Cenozoic paleovalleys of the lower Colorado River and their relation to river aggradation and degradation

Keith A. Howard, Scott C. Lundstrom, Daniel V. Malmon and Simon J. Hook
Age, distribution, and formation of late Cenozoic paleovalleys of the lower Colorado River and their relation to river aggradation and degradation (in Late Cenozoic drainage history of the southwestern Great Basin and lower Colorado River region; geologic and biotic perspectives, Marith C. Reheis (editor), Robert Hershler (editor) and David M. Miller (editor))
Special Paper - Geological Society of America (2008) 439: 391-410

Abstract

Distinctive far-traveled fluvial sediment of the lower Colorado River fills 20 paleo-valleys now stranded by the river downstream of Grand Canyon as it crosses the Basin and Range Province. These sediments resulted from two or more aggradational episodes in Pliocene and Pleistocene times following initial incision during the early Pliocene. A review of the stratigraphic evidence of major swings in river elevation over the last 5 m.y. from alternating degradation and aggradation episodes establishes a framework for understanding the incision and filling of the paleovalleys. The paleo-valleys are found mostly along narrow bedrock canyon reaches of the river, where divides of bedrock or old deposits separate them from the modern river. The paleovalleys are interpreted to have stemmed from periods of aggradation that filled and broadened the river valley, burying low uplands in the canyon reaches into which later channel positions were entrenched during subsequent degradation episodes. The aggradation-degradation cycles resulted in the stranding of incised river valleys that range in elevation from near the modern river to 350 m above it.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 439
Title: Age, distribution, and formation of late Cenozoic paleovalleys of the lower Colorado River and their relation to river aggradation and degradation
Title: Late Cenozoic drainage history of the southwestern Great Basin and lower Colorado River region; geologic and biotic perspectives
Author(s): Howard, Keith A.Lundstrom, Scott C.Malmon, Daniel V.Hook, Simon J.
Author(s): Reheis, Marith C.editor
Author(s): Hershler, Roberteditor
Author(s): Miller, David M.editor
Affiliation: U. S. Geological Survey, Menlo Park, CA, United States
Affiliation: U. S. Geological Survey, Denver, CO, United States
Pages: 391-410
Published: 2008
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 95
Accession Number: 2008-111798
Categories: Geomorphology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, sketch map
N32°00'00" - N36°00'00", W115°00'00" - W114°00'00"
Secondary Affiliation: Smithsonian Institution, USA, United StatesCalifornia Institute of Technology, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200841
Program Name: USGSOPNon-USGS publications with USGS authors
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