Monument Valley

Monument Valley, straddling the Arizona-Utah border on the Navajo Nation, is a valley studded with isolated sandstone buttes and mesas rising as much as 300 meters above the surrounding plain, formed from layered sedimentary rock of the Cutler Group, deposited during the Permian period roughly 270 million years ago. The formations owe their shape to differential erosion: a resistant caprock of Organ Rock Shale and de Chelly Sandstone sits atop softer underlying siltstone, and as wind and infrequent but powerful flash floods stripped away the surrounding weaker rock over millions of years, the harder-capped remnants were left standing as isolated buttes and pinnacles, including well known formations such as the Mittens and Merrick Butte. Known to the Navajo as Tse Bii' Ndzisgaii, the valley's striking silhouettes, further reddened by iron oxide within the rock, have made it one of the most widely recognized landscapes in the American West.