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[email protected]. GSA provides this and other forums for the presentation of diverse opinions and positions by scientists worldwide, regardless of their race, citizenship, gender, religion, or political viewpoint. Opinions presented in this publication do not reflect official positions of the Society. Geological Society of America Field Guide 6 2005 Birth of the lower Colorado River—Stratigraphic and geomorphic evidence for its inception near the conjunction of Nevada, Arizona, and California P. Kyle House Nevada Bureau of Mines and Geology, University of Nevada, Reno, Nevada 89557, USA Philip A. Pearthree Arizona Geological Survey, 416 W. Congress #100, Tucson, Arizona, 85701, USA Keith A. Howard U.S. Geological Survey, Menlo Park, California 94025, USA John W. Bell Nevada Bureau of Mines and Geology, University of Nevada, Reno, Nevada 89557, USA Michael E.