Greenhorn Formation (SDKg;0)

Gray shale, mudstone, marl, calcarenite, and shaley limestone grading upward into light-gray to tan, alternating marl and thin-bedded, fossiliferous limestone. Thickness 225-315 ft (69-96 m).

State	South Dakota
Name	Greenhorn Formation
Geologic age	Phanerozoic \| Mesozoic \| Cretaceous-Late
Original map label	Kg
Primary rock type	shale
Secondary rock type	mudstone
Other rock types	limestone
Lithologic constituents	Major Sedimentary > Carbonate > Limestone (Bed) Sedimentary > Carbonate > Marlstone (Bed) Sedimentary > Clastic > Mudstone (Bed) Sedimentary > Clastic > Mudstone > Shale (Bed)
Map 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
Unit 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
Geographic coverage	Butte - Custer - Fall River - Lawrence - Meade - Pennington