Badlands

Declared a national monument in 1939 and a national park in 1978, Badlands protects a landscape of eroded gullies and pinnacles that exposes one of the richest sequences of Oligocene mammal fossils in the world (some 33-23 million years ago), including primitive ancestors of horses, camels and rhinoceroses that then populated the North American plains. Its name comes both from the French settlers ('mauvaises terres') and from the Lakota ('mako sica'), each describing how inhospitable the ground is for farming or for travel.