Badlands

Along the Yellowstone River, the Terry Badlands rise in bands of sandstone, siltstone and coal. Water has cut the softer layers into gullies and ravines, leaving resistant rock as buttes, spires and natural bridges. Some hills are capped by clinker, rock baked hard when buried coal seams burned. In 1806 William Clark noticed coal and burnt-looking conical mounds while travelling along the Yellowstone.