Black hillsStratigraphy

Steven Dutch, Professor Emeritus, Natural and Applied Sciences, Universityof Wisconsin - Green Bay

Era Formation   Picture Notes
Tertiary Medicine Root Gravels 0-2 m    
Sharps 30 m Forms the tips of the highest Badlands pinnacles
Rockyford Ash 2-4 m A thin ledge-forming unit just below the tops of the pinnacles.
Brule 100 m Makes up most of the Badlands cliffs. Often banded white and pink.
Chadron 15-20 m From top to bottom: gray Chadron Formation, red Interior Paleosol, yellow Yellow Mounds Paleosol, and yellow-gray Fox hillsFormation.

The paleosols are not really a formation, but truncate a number of formations.

Interior Paleosol 1-2 m
Chamberlain Pass 0-4 m
Yellow Mounds Paleosol 2-5 m
Upper Cretaceous Fox hills 6-60 m
Pierre Shale 200 m + God must have been in a gray mood when he made this stuff and covered half of South Dakota with it.
Upper Cretaceous Niobrara Formation 80 m    
Upper Cretaceous Carlile Shale 150 m    
Upper Cretaceous Greenhorn Formation Upper Limestone 20 m    
Lower Shale 60-80 m
Upper Cretaceous Belle Fourche Shale 100 m    
Lower Cretaceous Mowry Shale 40 m    
Lower Cretaceous Newcastle Sandstone 10 m  
Lower Cretaceous Skull Creek Shale 60-80 m Dull gray shale with gypsum. Not the white nodular masses of the Spearfish but transparent blades, best seen by sun glint.
Lower Cretaceous Fall River Formation 40 m That's lignite at the bottom.
Lower Cretaceous Lakota Formation 70-110 m    
Upper Jurassic Morrison Formation 0-30 m   The Western Interior Jurassic formation.
Upper Jurassic Unkpapa Sandstone 15-40 m Not typical Unkpapa but striking. This purple and yellow striped facies is found in a small area not publicly accessible.
Upper Jurassic Sundance Formation 25 m Consists of a variety of sandstone and limestone members.
Permian Spearfish Formation   The Spearfish and Opeche Formations are all but indistinguishable, except that the Spearfish has abundant gypsum.
Permian Minnekahta Limestone   Pink, fine-bedded
Permian Opeche Formation   The Opeche can be told from the very similar Spearfish Formation by its lack of gypsum.
Pennsylvanian-Permian Minnelusa Formation   Gray but stained orange by the overlying formations.
Lower Mississippian Pahasapa Limestone   This is the cave-forming unit in the Black hills. Called Madison Limestone elsewhere and in older literature.
Upper Devonian - Lower Mississippian Englewood Limestone   This photo nicely shows the two-toned nature of the Englewood: pink below, buff above.
Cambrian Deadwood Formation   Various shades of red but has glauconitic members near the base in places.
  Unconformity   Here 500 m.y. Deadwood Sandstone rests on 1.7 b.y. old schist. One quarter of the age of the earth is missing here.

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Created 7 April 2003, Last Update 06 June 2020