Desert formations are landforms created by wind erosion and deposition in arid environments. Dunes are one of the most common desert formations, consisting of mounds or ridges of sand that can range from a few feet to hundreds of feet in height. They are formed when wind blows sand particles up the windward side of the dune, and then down the leeward side. Dunes can move over time, depending on the strength and direction of the wind.