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Basalt dike in orange-red Hakatai Shale along Colorado River at Hance Rapid, river mile 76.5, Grand Canyon. Isis Temple and Cheops Pyramid on a fault-block (horst), sitting on "island" of Shinumo Quartzite, of the Unkar Group. Bottom of the Unkar above Granite Gorge, and Vishnu Basement Rocks.
The Cardenas Basalt and Dox Formation are found mostly in the eastern region of Grand Canyon. The Shinumo Quartzite, Hakatai Shale, and Bass Formation are found in central Grand Canyon. The Unkar Group accumulated approximately between 1250 and 1104 Ma (1,104 million years ago, 1.1 billion).
The sills range in thickness from 23 m (75 ft) at Hance Rapids, eastern Grand Canyon, to 300 m (980 ft) in Hakatai Canyon in the Shinumo Creek area. The feeder dikes to these sills are not exposed. However, the feeder dikes for the Cardenas Basalt can be traced, discontinuously, to within a few meters of its base.
The Black Suspension Bridge (also known as the Kaibab Trail Suspension Bridge) spans the Colorado River in the inner canyon of Grand Canyon National Park. The span length is 440 feet (130 m). [ 1 ] The bridge is part of the South Kaibab Trail and is the river crossing used by mules going to Phantom Ranch .
The Grand Canyon Skywalk is a horseshoe-shaped cantilever bridge with a glass walkway at Eagle Point in Arizona near the Colorado River, on the edge of a side canyon in the Grand Canyon West area of the main canyon. [1] It opened as a tourist attraction in 2007, located outside the boundaries of the Grand Canyon National Park.
As in the case of the Grand Canyon asbestos deposits, dolomite and limestone reacted with silica-bearing fluids, heated by the basalt intrusions, forming the serpentine mineral chrysotile. Much like the Grand Canyon asbestos deposits, these basaltic sills and dikes range in age from 1,050 to 1,140 Ma.
The Grand Canyon Supergroup, of which the Unkar Group is the lowermost part, overlies deeply eroded granites, gneisses, pegmatites, and schists that comprise Vishnu Basement Rocks. [3] [5] [6] The Cardenas Basalt has also been called the Rama Formation.
The Uinkaret volcanic field is an area of monogenetic volcanoes in northwestern Arizona, United States, located on the north rim of the Grand Canyon. [2] Lava flows from the Uinkaret volcanic field that have cascaded down into the Grand Canyon, damming the Colorado River, have been used to date the canyon's carving. [3]