Tuesday, January 09, 2007

Slim Buttes, South Dakota

This past weekend we spent a few days hoofing about on Slim Buttes, South Dakota, in search of wild game.
These buttes have history. On September 8, 1876, Captain Anson Mills and 150 soldiers stumbled upon a camp of 25 to 30 lodges of Sioux and Cheyenne Indians on the eastern slopes of Slim Buttes. They attacked the following morning. At least ten Sioux and two cavalrymen died. This was only 11 weeks after the Battle of Little Bighorn. The battle site is about 8 miles southeast of Reva Gap. It is on private land.
These buttes have geology. They are Tertiary rocks and feature an outlier of the White River group, an Oligocene age badlands geology, most of which are found in southern South Dakota, western Nebraska, and eastern Colorado. You may remember seeing these rocks in Badlands National Park, where they form the famous mounds, spires, pinnacles, and hoodoos that draw millions to gawk and bake beneath the infernal badlands sun. Many end up languishing in Wall Drug, sloshing about, bellies full of ice water. But I digress.
Here we find two formations of the White River group, the Chadron and Brule. Above them lies the Arikaree formation, of more recent origin, deposited during the Miocene age. The White River group is underlian by Paleocene age Ludlow formation. The Ludlow formation contains lignites, and these coal veins were mined during the 1950's and 1960's for the urnanium they contained. Ground and surface water still contain elevated levels of uranium and there is concern about health hazards. Residents cite increased incidents of cancer.
The Arikaree formation contains "concretionary, cross-bedded, calcareous sandstones, siltstones, silty claystones, carbonates, and tuffaceous beds"¹, which is to say it has a lot of fine white sandstone and volcanic ash. It is ledge-forming, that is, it forms the cliffs that characterize the buttes. It is dramatic, a Ponderosa pine forest rising above the golden plains, perched atop sheer cliffs. One writer ranks Slim Buttes as one of the loveliest landscapes in South Dakota.²
Them is buttes alright.

The storied, seasoned, game hunter, Perry Dexter, spotting absolutely nothing, but what does it matter.

The Castles in Slim Buttes, a National Landmark.

Beneath the Arikaree formation cliffs. Trusted camp-hand Jim Nauertz is the dot in the center, living large.

¹ Hoganson, John W., Edward C. Murphy, Nels F. Forsman. 2006. Lithostratigraphy, Paleontology, and Biochronology of the Chadron, Brule, and Arikaree Formations in North Dakota. North Dakota Geological Survey, Bismarck, ND.

² Hogan, Edward Patrick, 1995. The Geography of South Dakota. Pinehill Press, Inc., Freeman, S.D.