Oglala National Grassland: The Toadstool Garden and the Time Before Grass

The formations at Toadstool Geologic Park look like a science fiction set: pedestals of pale clay with mushroom caps of harder sandstone balanced on top, eroded into shapes that architects might draw if they were trying to make something unprovable. They sit inside the Oglala National Grassland in the Nebraska Panhandle, a few miles from the Pine Ridge Reservation line, and they are old enough to put the word old into a different register.

The sediments here are Oligocene, deposited roughly thirty to thirty-five million years ago, when this region was a subtropical savannah crossed by slow meandering rivers. The bones of animals that have no living relatives erode continuously from the pale clay: titanotheres the size of modern rhinoceros, three-toed horses the size of dogs, ancient camels and giant tortoises and predatory entelodonts that looked like pigs designed by engineers who hated mercy. After a heavy rain, new material surfaces. Paleontologists come here specifically to walk the exposures the morning after storms.

The Lakota called this corner of the panhandle a passage country between the Pine Ridge to the south and the Niobrara country to the east. The Oglala National Grassland name reflects both: the Oglala Sioux Tribe's ancestral territory runs through this landscape, and what is now federal grassland was, within living memory, homestead land that failed. The Bankhead-Jones Farm Tenant Act of nineteen thirty-seven authorized the federal government to purchase those failed homesteads and convert them to managed public land. The Oglala Grassland is part of that buyout, a landscape that homesteaders broke, the Dust Bowl defeated, and the federal government purchased back and is now attempting to restore.

The Toadstool formations care nothing for any of this. They have been eroding at their own pace for thirty million years.