County of site: Harding County
Location of site: SD 20, ¼ mile W. of SD-79, E. of Buffalo, Reva
Year designated a landmark: 1976
Ownership: Federal
Size: 987 Acres
Camping fees: None
Drinking water: Not Available
Water available for washing or cleaning only
Firewood: No
Trash pick-up: No
Toilet: Yes
From Reva Gap Campground to The Castles roads are gravel, but good
Marker Text:
THE CASTLES
Administered by the Forest Service
United States Department of Agriculture
has been designated a
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REGISTERED
NATIONAL LANDMARK
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This site posses exceptional value
As an illustration of the Nation's Natural
Heritage and contributes to a better
Understanding of Man's environment
1979
Heritage Conservation and Recreation Service
United States Department of the Interior
The finding of Oligocene deposits Explained
The South Dakota Slim Buttes field trip notes kept by the University of Illinois
"Badlands are common in South Dakota west of the Missouri River, in the area known as the Missouri Plateau. Badlands formations often occur along the bluffs of the larger river valleys or on the sides of sizable buttes. Just west of the Little Missouri River, at the headwaters of the Moreau River, is an area known as the "Jump Off" badlands. Smaller areas of badlands can also be found along the edges of the Slim Buttes and Cave Hills and in the valleys of the Grand and Moreau Rivers.
"Why Are They Important?
Fossil Site - South Dakota badlands are famous as the source of fossil specimens of extinct mammal species. These mammals lived in the late Eocene and Oligocene epochs, between 57 and 26 million years ago.
Underlying the White River Badlands is the Pierre Shale, formed from the mud of a shallow inland sea that covered the mid section of the North American continent 80 million years ago. Fossils of ammonites, baculites, and other marine creatures are commonly found in Pierre Shale.
"Around 65 million years ago, the land was forced up, and the sea slowly drained away. A jungle developed on the exposed seabed, transforming the mud and shale into a bright yellow soil. During the Oligocene, the climate, at first warm and humid, became cool and dry.
"As the lands to the west rose even higher, sediment-loaded floods washed over this level region, depositing layer after layer of mud, volcanic ash and sand. Under pressure of successive layers, these sediments became soft rock. Throughout this period, a wide variety of mammals roamed the area. Some of these creatures died and were covered by the layers of sediment. Their remains, buried under the rock, fossilized. Beginning half a million years ago, erosion began to expose these fossils.
"Today, these rocks contain the best and most complete record of animals from the Oligocene epoch. The White River Badlands have been a rich source of information for paleontologists throughout the world, as they trace the development of ancient life forms.
"Geological Resource - Geologists studying the formation of badlands topography and the recent geological history of the earth also find much valuable evidence in the South Dakota badlands.
"Wildlife Habitat - Although by definition badlands contain very little vegetation, some plants, particularly prairie grasses, are found in South Dakota's badlands regions. Sod tables, remnants of the prairie that have resisted erosion, provide platforms for vegetation (see Figure 1). Cliff swallows, bighorn sheep and deer find protection in the maze-like gullies and ravines of badlands, a unique wildlife habitat." ~ Joan Steiner, Badlands National Park, Interior, SD