Hell Creek Formation

Tan to brown, light- to dark-gray, "somber beds" of shale. Interbedded with brown to red carbonaceous shale, gray and brown bentonitic silty shale, and gray, brown and yellow siltstone, sandstone, and claystone-pebble conglomerate. Thickness 260-600 ft (79-183 m).
State South Dakota
Name Hell Creek Formation
Geologic age Late Cretaceous
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone > Shale (Bed, Carbonaceous)
Minor
Sedimentary > Clastic > Conglomerate (Bed)
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Clastic > Siltstone (Bed)
References

Martin, J.E., Sawyer, J.F., Fahrenbach, M.D., Tomhave, D.W., and Schulz, L.D., 2004, Geologic Map of South Dakota: South Dakota Geological Survey, GM 10, scale 1:500,000.

NGMDB product
Counties Butte - Corson - Dewey - Harding - Meade - Perkins - Ziebach