Badlands, SW S.Dak., E of Black Hills; arid plateau (150 ft/46 m–300 ft/91 m above surrounding countryside), c.120 mi/193 km long, 30 mi/48 km–50 mi/80 km wide, bounded S by White R., crossed by Bad R. Characterized by numerous ridges and mesas cut by erosion into colorful peaks, pinnacles, and valleys, with scant vegetation. Region’s name has remained generic while lending the name to other areas of similar aspect. Rich in deposits of prehistoric fossils. Part of region (192.2 sq mi/497.8 sq km) in Pennington and Jackson cos. was set aside (1939) as Badlands Natl. Park. Similarly eroded region is in SW N.Dak., extending N-S along right bank of Little Missouri R.
