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| This view along the Bright Angel Trail shows the falls, plunge pools, and erosion-polished granite along a small tributary of Pipe Creek. The Vishnu Basement Rocks contains several large bodies of granitic rocks (including granite, granodiorite, pegmatite, and aplite). Zoroaster Granite is a historic name given granitic to the Granite Gorge (Powell's name for the Inner Gorge) and elsewhere in the region. However, these plutonic rocks (rocks that form from the cooling of igneous plutons) have a complex history and formed in various forms (small dike to great intrusive bodies) and over a long period of time. Absolute ages for plutonic rocks in the Grand Canyon range from 1840 to 1680 million years old. |
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