Geologic Map of the Meadview North Quadrangle, Mohave County, Arizona and Clark County, Nevada, by Mark A. Wallace, James E. Faulds, and Robert J. Brady, 2005

The Meadview North Quadrangle lies in the southern Grand Wash trough in the eastern Lake Mead region directly west of the abrupt margin of the Colorado Plateau and mouth of the Grand Canyon. Stratigraphic and structural relations within the quadrangle have important implications for understanding the paleo¬geographic evolution of the region. Fault blocks are tilted eastward and cut by west-dipping normal faults. Gently tilted middle to late Miocene sedimentary rocks, including the Hualapai Limestone, dominate the quadrangle and overlie moderately to steeply tilted Paleozoic sedimentary strata and Proterozoic gneisses and granitoids. The Hualapai Limestone is a lacustrine deposit that immediately predates arrival of the Colorado River. Stratigraphic relations and new age constraints indicate inception of the Colorado River between ~6 and 4.4 Ma. A 4.4 Ma basalt flow is interbedded with Colorado River gravels at Sandy Point. The stratigraphic framework, major structural features, and paleogeographic evolution of the quadrangle are discussed in the accompanying text.

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