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GEOLOGY DETERMINES WHERE THE TRAILS ARE LOCATED

If you visited vista points on the South Rim before embarking on your hike, you likely stared at the steep Kaibab Formation that forms a 350-foot-high cliff just about everywhere, providing few locations to descend below the rim. The Coconino Sandstone and Redwall Limestone form similarly impenetrable barriers. The Bright Angel Trail follows the Bright Angel Fault: Movement along the fault broke the solid rock, allowing erosion to proceed more rapidly. Eventually steep talus piles formed along the fault zone, allowing passage through otherwise vertical cliffs. In addition, the faulting has caused the rock on the southeast side of the fault to be about 200 feet lower than that on the northwest side, and the trail can snake back and forth across the fault depending on which side provides easier passage. The benefit of the fault scarp is especially visible where the Bright Angel Trail cuts through the Coconino Sandstone above the 1.5-Mile Resthouse and along Jacobs Ladder below the 3-Mile Resthouse. This fault first formed during the breakup of Rodinia 750 million years ago.