A mushroom rock, rock pedestal, or gour is a typical mushroom-shaped landform that is formed by the action of wind erosion. At an average height of two to three feet (0.6 to 0.9 m) from the base, the material-carrying capacity of the wind is at its maximum, so abrasion (erosion by wind in which transported materials hit an exposed rock surface and polish it or scratch it) is also maximized. In some cases, harder rocks are arranged horizontally over a softer rock, resulting in such erosion.