Phantom Ranch Tour - the Inner Gorge of the Grand Canyon

This zoomed-in view looks north from the Bright Angel Trail toward the Inner Gorge of the Grand Canyon. The image shows the unconformity (Greatest Angular Unconformity) 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 is part of the Unkar Group of Precambrian age (Late Proterozoic, about 1.2 billion years old). Another unconformity, 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.