Barren region covering some 2,000 sq mi (5,200 sq km) of southwestern South Dakota, U.S. It has an extremely rugged landscape almost devoid of vegetation.
It was created by cloudbursts that cut deep gullies in poorly cemented bedrock; its extensive fossil deposits have yielded the remains of such animals as the three-toed horse, camel, saber-toothed tiger, and rhinoceros. Badlands National Park (379 sq mi [982 sq km]), lying mostly between the Cheyenne and White rivers, was established as a national monument in 1939 and a national park in 1978.