Sunset on the Mittens, Monument Valley Tribal Park, Navajo Nation, Arizona

The massive towers of sandstone in this photograph have been dubbed “The Mittens”. They are all that remain of a once-vast plateau which covered this area now called Monument Valley. As this plateau eroded away, large mesas were reduced to smaller and smaller buttes which eventually eroded into these free-standing towers. The sheer vertical sandstone cliffs of these monoliths are composed of the De Chelly Sandstone which takes its name from the canyons just south of here. As the softer sloping ramp of Organ Rock Shale at the base of these towers erodes and undermines the De Chelly Sandstone above, huge unsupported blocks will continue to tumble down the slopes.