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This view is looking north from the Lakeview Overlook about 4 miles west of Hoover Dam. In the distance, this view shows the dark volcanic rocks of the northern Black Mountains and the more distant folded sedimentary rocks that make up the core of the Muddy Mountains north of the reservoir. The broad, open valley filled by the Boulder Basin portion of Lake Mead is a geologic contrast to the relatively narrow gorge cut by the Colorado River in Black Canyon where the dam was constructed. The broad basin reflects the erosional history of landscape in the Basin and Range Province. Boulder Basin is a north-trending structural basin that locally filled with alluvial sediments in Middle Miocene to Early Pliocene time, deposited about 15 to roughly about 4 million years ago. The modern Colorado River passage through the Grand Canyon and Lake Mead area developed about 5 to 4 million years ago and erosion has be gradually stripping away rocks and sediments, carving canyons, and wearing down the landscape since that time (Beard and others, 2007; Faulds and others, 2008). |
