Coal Vein Trail

The Coal Vein Trail in Theodore Roosevelt National Park's South Unit interprets a geological phenomenon unique to the North Dakota Badlands: lignite coal seams that caught fire through spontaneous combustion and burned for decades beneath the surface. The trailhead is located near the campground loop in the South Unit, and the 0.8-mile self-guided loop traverses an eerily colorful landscape where the underground combustion that started around 1951 baked the surrounding clay layers into brick-red and orange formations known as scoria or clinker. Informational signs along the route explain how the coal seams ignited naturally—likely triggered by lightning or prairie fire—and how the intense subsurface heat transformed surrounding materials. The burned-out vein area is now collapsed, creating a slightly sunken trench visible from the trail. Scoria, the clinker-like fused rock produced by the burning, is found throughout the Badlands region and gives many of the eroded buttes their distinctive rusty hue. The trail also offers good views of the Little Missouri River valley and the layered sedimentary badlands topography that Theodore Roosevelt himself explored extensively during his ranching years here from 1883 to 1886.