Desert formations are landforms that are created by the wind and sand in arid regions. A mesa is a flat-topped, steep-sided hill or ridge with a small, relatively level surface at the top. It is formed by erosion or by volcanic activity. A DUNE is a mound of sand that is formed by the wind, usually in desert areas. Sanddunes are large mounds of sand that are formed by the wind and are found in deserts and on beaches.