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Geologic units in Franklin county, Ohio

Columbus Limestone (Devonian) at surface, covers 35 % of this area

Columbus Limestone - Limestone and dolomite; gray to brown, weathers brown; massive bedding; upper 2/3 fossiliferous, gray limestone, lower 1/3 brown dolomite; 0 to 105 feet thick.

Ohio Shale (Devonian) at surface, covers 25 % of this area

Ohio Shale - Shale; brownish black to greenish gray, weathers brown; carbonaceous to clayey, laminated to thin bedded, fissile parting; carbonate and/or siderite concretions in lowermost 50 feet; petroliferous odor; 250 to 500+ feet thick. Includes Olentangy Shale south of central Delaware Co.

Lithology: black shale; shale

Delaware Limestone (Devonian) at surface, covers 23 % of this area

Delaware Limestone - Limestone; gray to brown; thin to massive bedded; argillaceous partings, nodules and layers, carbonaceous, petroliferous odor; as much as 45 feet thick.

Lithology: limestone

Berea Sandstone and Bedford Shale, Undivided (Devonian) at surface, covers 9 % of this area

Berea Sandstone and Bedford Shale, Undivided - Sandstone and shale; upper portion sandstone; brown, weathers light brown to reddish brown; thin to thick bedded, planar to lenticular bedding; minor shale interbeds; 5 to 75 feet thick, locally 100 to 125 feet thickness in Lorain, Cuyahoga, and Medina Counties; lower portion shale; gray to brown, locally reddish brown; thin to medium bedded, planar to lenticular bedding; interbedded siltstone and sandstone, ripple marks in siltstone beds; 80 to 180 feet thick, locally thin to absent where Berea Sandstone is thick.

Lithology: sandstone; shale; siltstone

Sunbury Shale (Mississippian) at surface, covers 6 % of this area

Sunbury Shale - Carbonaceous shale; black to brownish-black; very thinly laminated; 30 to 120 feet thick.

Lithology: black shale

Maxville Limestone; Rushville, Logan, and Cuyhoga Formations, Undivided (Mississippian) at surface, covers 2 % of this area

Maxville Limestone; Rushville, Logan, and Cuyhoga Formations, Undivided - Shale, siltstone, and sandstone, interbedded; various shades of gray, yellow to brown weather similar color; sandstone, silty to granular, local stringers of quartz pebbles. Shale, clayey to silty, locally fossiliferous. Medium to dark gray, thin to thick bedded limestone locally preserved at top of interval where unit crops out in southern half of state. Lithologies percentages vary in different areas where unit crops out; laterial and vertical gradation common at regional scale.

Tymochtee and Greenfield Formations, Undivided (Silurian) at surface, covers < 0.1 % of this area

Tymochtee and Greenfield Formations, Undivided - 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.