Douglas Group (IAPAd;0)

Douglas Group

Interval includes Stranger, Cass, Lawrence formations. Primary Lithologies: shale and mudstone, light to dark gray, part silt laminated. Secondary Lithologies: limestone, fossiliferous, part coated grain; siltstone to very fine sandstone; pedogenic mudstone, part red-brown, part calcareous/nodular. Minor: coal, carbonaceous shale; black shale. Maximum thicknesses 90-135 ft (27-41 m).

State	Iowa
Name	Douglas Group
Geologic age	Upper Pennsylvanian, upper Missourian-lower Virgilian
Lithologic constituents	Major Sedimentary > Clastic > Mudstone (Bed, Calcareous, Carbonaceous)light to dark gray, part silt laminated; minor pedogenic mudstone, part red-brown, part calcareous/nodular; incidental carbonaceous shale Sedimentary > Clastic > Mudstone > Shale (Bed)light to dark gray, part silt laminated Minor Sedimentary > Clastic > Siltstone (Bed)siltstone to very fine sandstone Sedimentary > Carbonate > Limestone (Bed)fossiliferous, part coated grain Incidental Sedimentary > Clastic > Mudstone > Shale > Black-shale (Bed) Sedimentary > Coal (Bed)
References	Witzke, Brian J., Anderson, Raymond R., and Pope, John P., 2010, Iowa Geological and Water Survey, DNR, Bedrock Geologic Map of Iowa, OFM-2010-1. Scale 1:500,000.
NGMDB product	NGMDB product page for 96753
Counties	Adair - Adams - Cass - Fremont - Madison - Mills - Montgomery - Pottawattamie - Ringgold - Taylor - Union

Douglas Group

Witzke, Brian J., Anderson, Raymond R., and Pope, John P., 2010, Iowa Geological and Water Survey, DNR, Bedrock Geologic Map of Iowa, OFM-2010-1. Scale 1:500,000.