Greenhorn Formation

Gray shale, mudstone, marl, calcarenite, and shaly limestone grading upward into light-gray to tan, alternating marl and thin-bedded, fossiliferous limestone. Thickness up to 40 ft (12 m).
State South Dakota
Name Greenhorn Formation
Geologic age Upper Cretaceous
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone > Shale (Bed)
Sedimentary > Carbonate > Marlstone (Bed)
Sedimentary > Clastic > Mudstone (Bed)
Minor
Sedimentary > Carbonate > Limestone (Bed)Shaly limestone grading upward into light-gray to tan, alternating marl and thin-bedded, fossiliferous limestone.
Sedimentary > Clastic > Sandstone > Arenite > Calcarenite (Bed)
References

Tomhave, D.W., and Schulz, L.D., 2004, Bedrock Geologic Map Showing Configuration of the Bedrock Surface in South Dakota East of the Missouri River, South Dakota Geological Survey, GM 9, scale 1:500,000.

NGMDB product
Counties Butte - Clay - Custer - Fall River - Grant - Hutchinson - Lawrence - Lincoln - Meade - Pennington - Roberts - Turner - Union - Yankton