Figure 9. Click in figure for larger image. Map showing the thickness of post-impoundment sediment in
Lake Mead. These sediments have accumulated since completion of the Hoover
Dam in 1935. The thickest part of the deposit fills the valley of the
Colorado River, while the Virgin River valley in Overton Arm and the Las
Vegas Wash valley in Las Vegas Bay both have a much thinner sediment cover.
The reason for this sediment distribution is because the Colorado River
supplies the majority of the sediment to the lake. Sediment is limited
to the deepest parts of the valleys because of dispersal by density flows.
The lettered bars mark the locations of profiles shown in Figure