Yellow Mounds Overlook sits in the most colorful part of Badlands geology. Yellow, purple, gray and striped reddish beds appear in order from bottom to top: the Yellow Mounds paleosol, the Interior Paleosol, the Chadron Formation and the Brule Formation. The yellow is a fossil soil, once the top of an old sea floor, stained by goethite. Nearby, 1950s survey markers are weathering out of the Chadron clay, a direct record of how fast this ground is wearing away. The Big Pig Dig, which ran from 1993 to 2008 near the Conata picnic area, produced more than 19,000 fossils, and the work there is finished. The small lot has no restroom. Badlands is an open-hike park, so visitors can walk among the mounds, but the clay is treacherous when it is wet.
These are the Yellow Mounds. If stopping cuts me off, tap play. The lot is at the bend, on the right, and if it's gone by, Conata Basin is next on the same side. It isn't a separate rock. It's old sea floor, weathered into soil and buried. Surveyors set metal markers flush with this ground in the nineteen fifties. Now they're weathering out of it. Parked? Stay put a moment. What's under the ground near here is Boone's, three minutes of it, and it begins by itself.
Photo: NPS / Larry McAfee, public domain · Public domain