From the Pinnacles Overlook, at the western end of the Badlands Loop, the earth looks as if it has been clawed open. Below the viewpoint, ridges and spires of soft rock drop steeply into a wide basin, their sides scored with gullies and streaked with bands of colour. The rock layers are sediments laid down over millions of years by ancient seas, rivers and volcanic ash falls from eruptions far to the west, and the badlands are eroding at a rate of about an inch a year, which in geological terms is lightning fast.
The badlands are one of the richest fossil beds in the world. The rocks contain the remains of ancient mammals that lived here more than thirty million years ago, including early horses, rhinoceroses, sabre-toothed cats and strange pig-like creatures called oreodonts. Palaeontologists have been digging here since the mid-nineteenth century, and new fossils are still being found, often exposed by the rains. If you see a fossil, leave it where it is and report it to a ranger.
The Lakota people, who lived on the surrounding prairies, called this land mako sica, meaning bad land, and early French fur traders called it les mauvaises terres à traverser, bad lands to travel across. The names were apt: the terrain is rough, water is scarce, and the summers are scorching. The southern part of the park lies within the Pine Ridge Indian Reservation and is managed jointly by the Oglala Lakota and the National Park Service.
Near the overlook, the Sage Creek Rim Road heads west along the edge of the badlands on gravel toward the Sage Creek Wilderness, where bison, bighorn sheep, pronghorn and prairie dogs roam. It is a beautiful ride, but the surface can be rough and dusty, and it becomes slippery and impassable after rain. On a road bike, stick to the paved loop.
The overlook is just a parking area and a railing. The road continues east along the edge of the badlands, with frequent viewpoints and short trails. Fuel and food are available in Wall, about fifteen kilometres to the north, and at Cedar Pass, near the eastern end of the loop. The best light is early morning and late afternoon, when the colours glow and the shadows bring out the shapes of the formations.