Monument Valley (Navajo: Tsé Biiʼ Ndzisgaii, meaning valley of the rocks) is a region of the Colorado Plateau characterized by a cluster of vast sandstone buttes, the largest reaching 1,000 ft (300 m) above the valley floor. It is located on the Arizona-Utah state line (around 36°59′N 110°6′W Coordinates: 36°59′N 110°6′W), near the Four Corners area. The valley lies within the range of the Navajo Nation Reservation and is accessible from U.S. Highway 163.
The area is part of the Colorado Plateau. The elevation of the valley floor ranges from 5,000 to 6,000 feet (1,500 to 1,800 m) above sea level. The floor is largely siltstone of the Cutler Group, or sand derived from it, deposited by the meandering rivers that carved the valley. The valley’s vivid red color comes from iron oxide exposed in the weathered siltstone. The darker, blue-gray rocks in the valley get their color from manganese oxide.
The buttes are clearly stratified, with three principal layers. The lowest layer is the Organ Rock Shale, the middle is de Chelly Sandstone, and the top layer is the Moenkopi Formation capped by Shinarump Conglomerate. The valley includes large stone structures including the famed “Eye of the Sun”.
Between 1948 and 1967, the southern extent of the Monument Upwarp was mined for uranium, which occurs in scattered areas of the Shinarump Conglomerate; vanadium and copper are associated with uranium in some deposits.
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