Toadstool Geologic Park

The geology here is the draw, and it's legitimately strange. Resistant sandstone slabs sit atop narrower pedestals of soft clay and siltstone — the harder cap protects the softer stem below from erosion, and over millions of years that process produces the mushroom shapes that give the park its name. The formations are geologically related to South Dakota's Badlands National Park, with the same layered sediments dating back 38–24 million years. The sediments also hold scientifically valuable fossil deposits: ancient horses, rhinoceroses, camels, saber-toothed cats, and entelodonts have all been found here, and a preserved trackway in the park captures what appears to be entelodonts pursuing two species of rhinoceros down an ancient stream channel. Fossils and artifacts are protected under federal law — collection is prohibited.

The access road is part of the experience, not a formality. Toadstool Road runs roughly 11 miles of unpaved gravel from Highway 2 to the park entrance, and conditions can change fast — the road becomes difficult to impassable after rain or snow. Plan accordingly and carry water, since none is available on-site. Once there, a one-mile interpretive loop trail from the campground covers the main formations, with a self-guided brochure available at the trailhead kiosk. The campground has 12 sites with picnic tables, fire rings, and vault toilets, and is open year-round. There is no gas, food, or lodging nearby.