White Mesa, located along U.S. Route 160, Arizona, lies on diputed Hopi-Navajo land area. In this Picture of the Day, the white cliffs are enhanced by the early morning sunrise. Sandstone layers (strata) in this area vary from yellow, black, green, red, white, to pink, depending on their age. This white layer of sandstone is bonded with limestone and is nearly pure silica. The 2,300 foot thick deposit is thought to have originated in Canada and blown into what once was a Colorado/Arizona lowland.