Though it was established as a national park in 1978, the Badlands’ rock formations started to take shape 69 million years ago. Back then the region was covered by ocean water. When the sea retreated, it left behind bits of rock called sediment. Half a million years ago, wind and rain began to erode the sediment, carving out buttes as well as slender rock towers called pinnacles.
Now scientists study rocks in the park to find out how the environment here has changed over time. The rocks also contain clues about what types of animals once lived in the area. Archaeologists have unearthed the fossil of an ancient creature called the sabertooth cat as well as the bones of rhino ancestors.
Badlands National Park isn’t completely filled with buttes and pinnacles. Areas with these rock formations are surrounded by grasslands, which support bison, prairie dogs, and other animals. And the land in the park is still changing. The rock formations continue to erode—up to an inch a year in some spots. Eventually wind and water will wear down the entire Badlands until it becomes flat land. Luckily you still have plenty of time to visit and gawk at those rocks!