Tim Fitzharris / Sandstone striations and erosional features, Badlands National Park, South Dakota

Tom Vezo / Mushroom hoodoo rock formations, Bisti Wilderness Area, New Mexico

Tom Vezo / Mushroom hoodoo rock formation, Bisti Wilderness Area, New Mexico

Sumio Harada / Eroded sandstone formation, Badlands National Park, South Dakota

Tim Fitzharris / Badlands National Park, South Dakota

Tim Fitzharris / Badlands National Park, South Dakota

Tim Fitzharris / Badlands National Park, South Dakota

Tim Fitzharris / Eroded buttes showing layers of sedimentary rock, Badlands National Park, South Dakota

Tim Fitzharris / Eroded buttes showing layers of sedimentary rock, Badlands National Park, South Dakota

Tim Fitzharris / Detail of erosional feature, Badlands National Park, South Dakota

Tim Fitzharris / Eroded buttes and prairie in Badlands National Park, South Dakota

Tim Fitzharris / Eroded buttes and prairie in Badlands National Park, South Dakota

Tim Fitzharris / Upper prairie in Badlands National Park, South Dakota

Tim Fitzharris / Mule Deer (Odocoileus hemionus) trio in the grasslands of Badlands National Park, South Dakota

Tim Fitzharris / Landscape showing erosional features in sandstone amid grassland, Badlands National Park, South Dakota

Tim Fitzharris / Landscape showing erosional features in sandstone, Badlands National Park, South Dakota

Tim Fitzharris / White River Overlook showing sandstone striations and erosional features, Badlands National Park, South Dakota

Tim Fitzharris / Sandstone striations and erosional features, Badlands National Park, South Dakota

Tim Fitzharris / Landscape showing erosional features with grassland, Badlands National Park, South Dakota

Tim Fitzharris / Badlands in Theodore Roosevelt National Park, North Dakota

Tim Fitzharris / Storm cloud lit by setting sun over the prairie, Badlands National Park, South Dakota

Gerry Ellis / Vista of eroded sedimentary rock in the Black Hills, Badlands National Park, South Dakota

Gerry Ellis / Eroded landform, Badlands National Park, South Dakota

Jim Brandenburg / Sedimentary layers exposed by erosion, Badlands National Park, South Dakota

Jim Brandenburg / Clouds rolling across mountain range at twilight, Badlands National Park, South Dakota

Jim Brandenburg / Sedimentary layers exposed by erosion, Badlands National Park, South Dakota

Jim Brandenburg / Eroded sedimentary formations, Badlands National Park, South Dakota

Jim Brandenburg / Eroded gully in sedimentary soils, Badlands National Park, South Dakota

Jim Brandenburg / Sunset in January, Badlands National Park, South Dakota

Jim Brandenburg / Barren, sedimentary hills eroded by wind and weather, Badlands National Park, South Dakota

Jim Brandenburg / Sedimentary hills sculpted by wind and weather, Badlands National Park, South Dakota

Jim Brandenburg / Eroded sedimentary hills, Badlands National Park, South Dakota

Jim Brandenburg / Eroded landscape, Badlands National Park, South Dakota

Jim Brandenburg / Saber-toothed Tiger skull fossil, Badlands National Park, South Dakota

Jim Brandenburg / Badlands National Park by moonlight, South Dakota

Jim Brandenburg / Badlands National Park by moonlight, South Dakota