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| This zoomed-in view looking north from the Bright Angel Trail toward the Inner Gorge of the inner Colorado River passage of the Grand Canyon. The image shows the nonconformity between the underlying crystalline rocks (Vishnu Basement Rocks) and the overlying horizontal limestone beds of the Bass Formation. In turn, the Bass Formation is overlain by the Hakatai Shale and the Shinumo Quartzite. The Bass-Hakatai-Shinumo sequence are part of the Unkar Group of Precambrian age (Late Proterozoic, about 1.2 billion years old). The Great Unconformity runs along the top of the top of the Shinumo Quartzite beneath the overlying Tapeats Sandstone which is partially visible at the top of the Inner Gorge (as mapped by Billingsley, 2000). On the right, folded layers of limestone of the Bass Formation terminate against offset granitic rocks along a fault. In this view, the fault is a high-angle reverse fault. |
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