The Bardenas Reales is a semi-desert natural region, or badlands, of some 42,000 hectares in southeast Navarre. The soils are made up of clay, chalk, and sandstone and have been eroded by water and wind creating surprising shapes, canyons, plateaus, tabular structures, and isolated hills, called cabezos. Bardenas Reales lacks urban areas, vegetation is scarce and the many streams that cross the territory have a markedly seasonal flow, staying dry most of the year.