Bright Angel Shale Coconino Sandstone Hermit Shale Hualapai Tribe Kaibab Limestone Muav Limestone Paleozoic Strata Redwall Limestone Supai Formation Torweap Formation american history arizona az canyons colorado river desert edge erosion grand canyon grand canyons grandcanyon history indian indians landscape layers mountains native american native american indians native americans navajo overlook rim to rim rocks scenic overlook sediments southwest tapeats Sandstone time tourism tourists u.s.a. united states of america usa west rim