Lake Mead - Boulder Basin

Boulder Basin is the large, open part of Lake Mead just north of Hoover Dam. This view is looking east from Boulder Beach toward the high cliffs of middle Miocene-age basalt flows that cap a plateau (Fortification Hill) in the Black Mountains on the east (Arizona) side of the Colorado River Valley near Hoover Dam. Numerous lava flows are exposed in the Fortification Hill volcanic section. These volcanic flows accumulated in the ancestral Boulder Basin valley prior to the development of the modern Colorado River (Grand Canyon) drainage system. Lake Mead National Recreation Area is situated in the eastern Basin and Range Province. The province is characterized by a series of generally north-trending mountain ranges and intervening sediment-filled valleys (or basins) (Faulds and others, 2008). To the east, Lake Mead National Recreation Area borders Grand Canyon-Parashant National Monument and Grand Canyon National Park. These parks are on both on the western end of the Colorado Plateau Province.