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GMEG - Geology, Minerals, Energy, & Geophysics Science Center

Geologic and Geomorphic Evolution of the lower Colorado River




Geology and geomorphology of the northern Lower Colorado River Corridor

Index map showing geologic mappint in the study area

Focus on 1:50,000-scale geologic mapping of the river corridor and studies of the evolution and integration of the river system from Hoover Dam south to Yuma.

Geologic mapping of the northern Colorado River corridor (NoCOLO), which transects Cottonwood, Mohave, and Chemehuevi Valleys; and the bedrock reaches of Black Canyon, Pyramid Canyon, Mohave Canyon / Topock Gorge, and part of Monument Canyon north of Parker Dam. Valleys along this reach of the river contain extensive remnants of late Cenozoic river and tributary stratigraphic units that support the model for river integration by a downstream-directed process of lake spillover. Additional mapping in this area will help further test this model through identification, delineation, description, and dating of key deposits and landforms. Mapping of the distribution of key units throughout this entire area will also provide a very useful data set for testing hypotheses relating to modes and consequences of river integration and will allow for an assessment of potential tectonic controls on paleo-river profiles. The mapping will also identify key, previously unknown targets for geochronologic, geochemical, and paleontological sampling campaigns.

Objectives: The primary objective of this task is to develop a 1:50,000 geologic map of the northern Colorado River river corridor (NoCOLO) between Hoover Dam and Parker Dam. The task involves the concurrent development of a surficial geologic map and a bedrock geologic map. The map will leverage published and ongoing 1:24k mapping by NBMG, AZGS, and USGS. New 1:50,000-scale mapping will extend the existing mapping to the project boundary. Field efforts will focus on refinement of older mapping and new mapping; identification and analysis of paleontological features; and collection and analysis of datable materials, mainly volcanic ash beds that are present in the area.



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