The Cincinnati Group is a geologic group in Kentucky, Ohio and Indiana. It is Upper Ordovician in age. This geologic group is made up of member formations: Drakes Formation, Whitewater Formation, Liberty Formation, Arnheim Formation, Grant Lake Limestone, Miamitown Shale, Fairview Formation, and Kope Formation. There are also several members of the respective formations.[1] Most of these formations are highly fossiliferous.
Stratigraphy
Drakes Formation
The Drakes Formation is a geologic formation in Kentucky. It preserves fossils dating back to the Ordovician period.
The Drakes Formation was named by Weir for outcrops near the East Fork of Drakes Creek in the Paint Lick quadrangle, southwestern east-central Kentucky.[2] This formation ranges from 20 ft to 150 ft thick, thinning northward. It includes four members, Saluda Dolomite Member, Preachersville Member, Rowland Member and Bardstown Member. These formations are made up of interbedded limestone and shale with units of dolomite ranging from a few inches to a few feet think.
Whitewater Formation
The Whitewater Formation is a geologic formation in Ohio and Indiana. It preserves fossils dating back to the Ordovician Period.[3]
The Whitewater was first named by J. M. Nickles in 1903.[4] He described exposures of limestone and interbedded calcareous shale along the Whitewater River at Richmond, Wayne County, Indiana.
An excellent exposure of the Whitewater Formation is a roadcut located on Route 27 south of Richmond, Indiana, at 39.7877 N, -84.9014 W. It is typically called “Richmond South” in field guides and other publications.
-
Fossiliferous slab -
Rugosa corals -
-
Small brachiopod -
Another brachiopod -
Liberty Formation
The Liberty Formation is a geologic formation in Ohio and Indiana. It preserves fossils dating back to the Ordovician Period.
Waynesville Formation
The Waynesville Formation is a geologic formation in Ohio and Indiana. It preserves fossils from the Late Ordovician Period.
Paleofauna
The Cincinnati Group Has produced many fossil animals. The stratigraphy of the Cincinnati Group is complex and the different constituents unit(Elkhorn,Liberty,Saluda,and Whitewater Formations) Are interpreted as being a complex and coeval system of laterally equivalent environments.[5]
Cephalopoda
| Genus | Species | Material | Notes |
|---|---|---|---|
| Narthecoceras | N.dunni | Shells | A large 3 m Orthoconic nautiloid.[6] |
| Endoceras | E.proteiforme | Shells | A gigantic orthoconic nautiloid,at least 4.6 m.[7][8] |
| Lambeoceras | L.richmondese | Shells | A moderately large nautiloid 1 m shell length.[7] |
| Treptoceras | T.sp. | Shells | A small 20 cm nautiloid.[9][10] |
| Nautiloid indet. | Indet | Shells | Numerous indeterminate nautiloids.[7] |
Arthropoda
| Genus | Species | Material | Notes |
|---|---|---|---|
| Isotelus | I.maximus | Numerous specimens | Giant 50 cm trilobite.[7] |
| Megalograptus | M.ohioensis | Holotype specimen | Large 80 cm eurypterid.[7] |
See also
- List of fossiliferous stratigraphic units in Kentucky
- List of fossiliferous stratigraphic units in Ohio
- List of fossiliferous stratigraphic units in Indiana
References
- ^ Davis, R. A. (1986). “Cincinnati region: Ordovician stratigraphy near the southwest corner of Ohio”. Southeastern Section of the Geological Society of America. Geological Society of America. pp. 21–24. doi:10.1130/0-8137-5406-2.21. ISBN 978-0-8137-5406-2. Retrieved 2025-06-16.
- ^ Calloway Creek limestone and Ashlock and Drakes Formations (Upper Ordovician) in south-central Kentucky (Report). US Geological Survey. 1965. doi:10.3133/b1224d.
- ^ “Geolex — Whitewater”. ngmdb.usgs.gov. Retrieved 2025-06-16.
- ^ Nickles, J. M., 1903, The Richmond Group in Ohio and Indiana and its subdivisions, with a note on the genus Strophomena and its type: American Geologist, v. 32, p. 202–218.
- ^ Davis, Richard (1998). “SAMPLING THE LAYER CAKE THAT ISN’T: THE STRATIGRAPHY AND PALEONTOLOGY OF THE TYPE-CINCINNATIAN” (PDF).
- ^ “Dodges creek locality”.
- ^ a b c d e Collins, Horace (1970). “Ohio fossils” (PDF).
- ^ “Endoceras proteiforme”. Atlas of Ordovician Life. 2013-12-06. Retrieved 2026-04-29.
- ^ “Warren county site”.
- ^ “Treptoceras duseri”. Atlas of Ordovician Life. 2013-12-06. Retrieved 2026-04-29.