Minnekahta Limestone and Opeche Shale

Minnekahta Limestone-Purple to gray, finely crystalline, thin- to medium-bedded limestone with varying amounts of red shale. Thickness 30-50 ft (9-15 m). Opeche Shale- Red siltstone, argillaceous sandstone and shale interbedded with caliche layers. Thickness 85-130 ft (26-40 m).
State South Dakota
Name Minnekahta Limestone and Opeche Shale
Geologic age Permian
Lithologic constituents
Sedimentary > Clastic > Mudstone > Shale (Bed)
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Carbonate > Limestone (Bed)

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 Custer - Fall River - Lawrence - Meade - Pennington