Little Missouri National Grassland Bentonite Hills Trail

The Bentonite Hills Trail cuts a 22-mile arc through some of North Dakota’s most otherworldly terrain, where ancient seabeds have eroded into a moonscape of clay spires and multicolored mudstone that looks more Mars than Midwest. Starting from the Burning Coal Vein parking area, the route follows old oil exploration roads through the Sentinel Butte formation, passing active paleontology sites where 65-million-year-old dinosaur bones still emerge from the bentonite clay after every thunderstorm.

Don’t let the moderate rating fool you — when wet, this bentonite clay becomes automotive quicksand that’ll bog down anything without aggressive tread and momentum. Stock high-clearance vehicles handle it fine in dry conditions, but check weather religiously and carry recovery gear. Best season runs May through October, avoiding spring mud and winter freeze-thaw cycles. The reward is absolute solitude, world-class stargazing, and geology so alien you’ll question which planet you’re actually exploring.