slickrock

Bare, smooth expanses of sandstone, most characteristically the Navajo and Entrada sandstones of the Colorado Plateau — sweeping curves of petrified dunes, often buff, salmon, or red, worn smooth by wind and water into a flowing, organic topography. The name is misleading: slickrock is not slick. Dry sandstone provides excellent traction for boots and tires. The name comes from early stockmen whose iron-shod horses slipped on it.