The Bárdenas Reales is a semi-desert natural region, or badlands, of some 42,000 hectares (100,000 acres) in southeast Navarre, bordering Aragon (Spain). 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 seamounts. Bárdenas 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. Summers are very hot, winter are cold. It is classified Natural Park in 1999 by the Parliament of Navarra, Reserve of the Biosphere by UNESCO in 2000.