Extensive area of flat upland, usually bounded by an escarpment on all sides but sometimes enclosed by mountains. Plateaus are extensive, and together with enclosed basins they cover about 45% of the Earth's land surface. The essential criteria for a plateau are low relative relief and some altitude. Low relief distinguishes plateaus from mountains, although their origin may be similar. Plateaus, being high, often create their own local climate; the topography of plateaus and their surroundings often produce arid and semiarid conditions.