|Name||Estill Shale and Drowning Creek Formation, Undivided|
Sedimentary > Carbonate > Dolostone (Bed)Estill Shale: minor interbedded dolomite. Drowning Creek Formation: dolomite, bluish gray to gray weathers yellowish orange; argillaceous and silty in part; planar to lenticular, thin to thick bedded; 20 to 90 feet thick.
Sedimentary > Clastic > Mudstone > Shale (Bed)Estill Shale: reddish to greenish gray, weathers light gray, planar to irregular bedding, thin to thick bedded, 30 to 180 feet thick. Drowning Creek Formation: minor shale.
Slucher, E.R., (principal compiler), Swinford, E.M., Larsen, G.E., and others, with GIS production and cartography by Powers, D.M., 2006, Bedrock geologic map of Ohio: Ohio Division of Geological Survey Map BG-1, version 6.0, scale 1:500,000.