Geologic units in Greene county, Ohio

Cincinnati Group as used by Wickstrom (1990) (Ordovician) at surface, covers 30 % of this area

Shale, dolomite and limestone, interbedded. Various shades of gray; thin to medium bedded; Data from core holes. Occurs beneath glacial drift.

Cedarville, Springfield, and Euphemia Dolomites, Undivided (Silurian) at surface, covers 21 % of this area

Cedarville Dolomite, white to gray to blue gray, weathers gray, abundant intercrystalline, moldic, and vuggy porosity, massive bedded, 0 to 100 feet thick. Diagnostic features include porosity, cliff-forming nature of unit, and pentameriid brachiopod fossil zone near contact with Springfield Dolomite. Springfield Dolomite, gray to tan, mottled with brownish gray, massive bedded where unweathered and layered bricklike where weathered, 5 to 10 feet thick. Euphemia Dolomite, dolomite to dolomitic limestone, gray to bluish gray, massive bedded, 5 to 15 feet thick. Diagnostic features include large, blocky bedding where weathered and cliff forming nature. Interval ranges from 10 to 125 feet in thickness. Euphemia Dolomite averages 1.6 to 2.6 m in thickness. Environment of deposition was normal marine offshore, free from clastic influence; similar to Cedarville Dolomite. Unconformably overlies Massie Shale. Correlates with Bisher Formation to the southeast. Age is Wenlockian (Ausich, 1987).

Tymochtee and Greenfield Formations, Undivided (Silurian) at surface, covers 12 % of this area

Dolomite, olive-gray to yellowish- brown, thin to massive bedded, upper two-thirds commonly contains brownish-black to gray shale laminae; locally developed brecciated zones in lower one third.

Massie and Osgood Shales; Dayton and Brassfield Limestones; Laurel Dolomite; Undivided (Silurian) at surface, covers 11 % of this area

Massie Shale; gray to bluish gray; planar to irregular, thin to thick bedded; calcareous; slakes; minor limestone and dolomite beds; 0 to 10 feet thick. Laurel Dolomite; gray to tan, weathers brown; argillaceous to nonargillaceous; wavy, thin to medium bedded; 5 to 10 feet thick. Osgood Shale, blue gray to gray weathers brown; thin to massive bedded; calcareous with minor limestone and dolomite; slakes and slumps readily in outcrop; 3 to 25 feet thick. Dayton Limestone; gray to bluish-gray weathers grayish-white; medium to thick bedded; fine grained; dolomitic; 5 to 15 feet thick. Brassfield Limestone; white to pink, locally gray to reddish brown; irregular, thin to medium bedded; coarsely crystalline; abundant pelmatozoan fossils; grayish-green glauconitic partings; cliff forming; 20 to 50 feet thick. Interval ranges from 32 to 100 feet in thickness.

Drakes, Whitewater and Liberty Formations, Undivided (Ordovician) at surface, covers 8 % of this area

Drakes Formation; shale (90%) and limestone/dolomite (10%), interbedded; gray and maroon, weathers yellowish gray; planar to irregular, thin to thick bedded; 20 to 30 feet thick. Whitewater Formation, limestone (60%) and shale (40%) interbedded; gray weathers yellowish gray; irregular to wavy, thin to medium bedded; 20 to 80 feet thick. Liberty Formation, limestone (50%) and shale (50%), interbedded; gray weathers yellowish gray; planar to irregular, thin to medium bedded; 20 to 40 feet thick. Interval ranges from 60 to 150 feet in thickness. 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).

Waynesville and Arnheim Formations, Undivided (Ordovician) at surface, covers 7 % of this area

Waynesville Formation, shale (70%) and limestone (30%) interbedded; gray to bluish gray weathers light gray; planar to irregular, thin to thick bedded; 90 to 120 feet thick. Arnheim formation, shale (60%) and limestone (40%) interbedded; gray to bluish gray weathers light gray; planar, wavy, irregular, to nodular (in upper portion), thin to thick bedded; 50 to 100 feet thick. Contains multiple sedimentary cycles consisting of the alternation of shale and limestone displaying planar to irregular bedding with limestone and shale exhibiting wavy to nodular bedding. Ranges from 140 to 220 feet. 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).

Grant Lake and Fairview Formations, Miamitown Shale, Undivided (Ordovician) at surface, covers 5 % of this area

Limestone (50%) and shale (50%), interbedded; gray to bluish-gray weathers light gray to yellowish-gray;, planar to lenticular, thin to medium bedded in lower half; wavy to irregular to nodular, thin to thick bedded in upper half; fossiliferous. Interval of shale (90%) with limestone (10%), as much as 35 feet thick, near middle of unit.

Cedarville, Springfield, Euphemia, and Laurel Dolomites; Massie Shale, Undivided (Silurian) at surface, covers 4 % of this area

Cedarville Dolomite, white to gray to blue gray weathers gray; abundant intercrystalline, moldic, and vuggy porosity, massive bedded, 0 to 100 feet thick. Diagnostic features include porosity, cliff-forming nature of unit, and pentamerid brachiopod fossil zone near contact with Springfield Dolomite. Springfield Dolomite, gray to tan, mottled with brownish gray, massive bedded where unweathered and layered brick-like where weathered, 5 to 10 feet thick. Euphemia Dolomite, dolomite to dolomitic limestone, gray to bluish gray, massive bedded, 5 to 15 feet thick. Diagnostic features include large, blocky bedding where weathered and cliff forming nature. Massie Shale, gray to bluish gray, minor limestone and dolomite beds, calcareous, slakes easily, planar to irregular bedding, thin to thick bedded, 0 to 10 feet thick. Diagnostic feature includes calcareous shale with limestone and dolomite. Laurel Dolomite, gray to tan, weathers brown, argillaceous to nonargillaceous, wavy bedding, thin to medium bedded, 5 to 10 feet thick. Interval ranges from 115 to 140 feet thick. Euphemia Dolomite averages 1.6 to 2.6 m in thickness. Environment of deposition was normal marine offshore, free from clastic influence; similar to Cedarville Dolomite. Unconformably overlies Massie Shale. Correlates with Bisher Formation to the southeast. Age is Wenlockian (Ausich, 1987).

Dayton and Brassfield Limestones (Silurian) at surface, covers 0.4 % of this area

Dayton Limestone; gray to bluish-gray weathers grayish-white; medium to thick bedded; fine grained; dolomitic; 5 to 15 feet thick. Brassfield Limestone; white to pink, locally gray to reddish brown; irregular, thin to medium bedded; coarsely crystalline; abundant pelmatozoan fossils; grayish-green glauconitic partings; cliff forming; 20 to 50 feet thick. Interval ranges from 32 to 100 feet in thickness.

Estill Shale (Silurian) at surface, covers 0.2 % of this area

Shale and minor dolomite interbedded, reddish to greenish gray, weathers light gray, planar to irregular bedding, thin to thick bedded, 30 to 180 feet thick. Diagnostic features include dominance of shale and the units susceptibility to be unstable on slopes and cause landslides.

Clinton and Cataract Groups, Undivided (Silurian) at surface, covers 0.2 % of this area

Dolomite, limestone and shale, interbedded. Various shades of gray, olive green, yellow and reddish-gray; laminated to thick bedded; argillaceous, glauconitic, pyritic, ferruginous and/or phosphatic; locally fossiliferous. Data from core holes. Occurs beneath glacial drift.