Mowry Shale, Newcastle Sandstone, and Skull Creek Shale (SDKms;0)

Mowry Shale- Black to gray, siliceous, fissile shale and siltstone containing bentonite layers, and sparse sandstone dikes and sills. Thickness 125-250 ft (38-76 m). Newcastle Sandstone- Gray, light-brown to yellow, discontinuously distributed siltstone, claystone, sandy shale, and fine-grained sandstone. Thickness up to 290 ft (88 m). Skull Creek Shale- Dark-gray to blueish-gray shale containing ferruginous, and carbonate concretions. Thickness 150-275 ft (46-84 m).

State	South Dakota
Name	Mowry Shale, Newcastle Sandstone, and Skull Creek Shale
Geologic age	Phanerozoic \| Mesozoic \| Cretaceous-Early
Original map label	Kms
Primary rock type	shale
Secondary rock type	siltstone
Other rock types	sandstone; claystone
Lithologic constituents	Major Sedimentary > Clastic > Siltstone (Bed) Sedimentary > Clastic > Mudstone > Shale (Bed) Minor Sedimentary > Clastic > Mudstone > Claystone (Bed) Sedimentary > Clastic > Sandstone (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