Cincinnati Group as used by Wickstrom (1990) (OHOc;0)

State	Ohio
Name	Cincinnati Group as used by Wickstrom (1990)
Geologic age	Ordovician
Original map label	Oc
Comments	Secondary unit descriptions from USGS Lexicon website (ref. OH017) and OH009, OH011: In northwestern OH, overlies the Trenton Limestone and the Point Pleasant Formation. In the subsurface of the report area the unit is undifferentiated, though the basal Kope Formation can be identified. Preliminary correlations indicate a great deal of intertonguing and many facies changes above the Kope. Basal portion of the Cincinnati is composed of light- to dark-gray shales and silty shales grading upward into light-gray to green calcareous shales intermixed and interlayered with fine- to medium-crystalline fossiliferous limestones and dolomites. Group thickens from less than 700 ft in extreme western OH to approximately 950 ft on the eastern edge of the study area (Wickstrom and others, 1992). The Geological Survey of Ohio recognizes the Cincinnati Group proposed by Meek and Worthen (1865), but at this time retains it as an informal term. The unit will be formally reinstated as a lithostratigraphic term after revision of its lower boundary and minor lithologic redescription of its units are completed. The ten formations included in the group are the (ascending) Clays Ferry Formation, the Kope Formation, the Fairview Formation, the Miamitown Shale, the Grant Lake Limestone, the Arnheim Formation, the Waynesville Formation, the Liberty Formation, the Whitewater Formation, and the Drakes Formation. Six members have been identified in the course of field mapping: the Point Pleasant Tongue of the Clays Ferry, the informal Bellevue, Corryville, Mount Auburn, and Straight Creek members of the Grant Lake Limestone, and the Preachersville Member of the Drakes Formation. The Backbone Creek and Elk Creek beds are recognized as excellent stratigraphic marker beds (Shrake and others, 1988).
Primary rock type	shale
Secondary rock type	dolostone (dolomite)
Other rock types	limestone
Lithologic constituents	Major Sedimentary > Clastic > Mudstone > Shale (Bed)Shale, dolomite and limestone, interbedded. Various shades of gray; thin to medium bedded. Minor Sedimentary > Carbonate > Dolostone (Bed)Shale, dolomite and limestone, interbedded. Various shades of gray; thin to medium bedded. Sedimentary > Carbonate > Limestone (Bed)Shale, dolomite and limestone, interbedded. Various shades of gray; thin to medium bedded.
Map references	Digital Ohio map from CD produced as a result of a contract between the U.S. Geological Survey and the Ohio Geological Survey. Released with permission of the Ohio Geological Survey, June 2005.
Unit references	Digital Ohio map from CD produced as a result of a contract between the U.S. Geological Survey and the Ohio Geological Survey. Released with permission of the Ohio Geological Survey, June 2005. File of unit descriptions received from Ohio Geological Survey. Wickstrom, L.H., Gray, J.D. and Stieglitz, R.D., 1992, Stratigraphy, structure, and production history of the Trenton Limestone (Ordovician) and adjacent strata in northwestern Ohio: Ohio Division of Geological Survey Report of Investigations, no. 143, 78 p. Shrake, D.L., Schumacher, G.A. and Swinford, E.M., 1988, Field guidebook to the stratigraphy, sedimentology, and paleontology of the Upper Ordovician Cincinnati Group of southwest Ohio: Ohio Division of Geological Survey, Society of Economic Paleontologists and Mineralogists, 5th Midyear Meeting, 81 p. USGS Geologic Names Lexicon (GEOLEX) [http://ngmdb.usgs.gov/Geolex/]
Geographic coverage	Auglaize - Champaign - Clark - Clinton - Darke - Greene - Logan - Madison - Mercer - Miami - Montgomery - Preble - Shelby