So stark and forbidding are the chiseled spires, ragged ridgelines, and deep ravines of South Dakota's badlands that Lieutenant Colonel George Custer once described them as "hell with the fires burned out." Although a bit more accessible than the depths of the underworld, the landscape is easily the strangest in the Great Plains. Ruthlessly ravaged over the ages by wind and rain, the 380 square miles of wild terrain continue to erode and evolve, sometimes visibly changing shape in a few days. Prairie creatures thrive on the untamed territory, and animal fossils are in abundance.