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Mineral Resources > Online Spatial Data > Geology > by state > Ohio Geology

Geologic units in Logan county, Ohio

Salina Group (Silurian) at surface, covers 40 % of this area

Salina Group - Dolomite, gray, yellow-gray to olive-gray, laminated to thin bedded; occasional thin bed and laminae of dark gray shale and anhydrite and/or gypsum; brecciated zones in part.

Lithology: dolostone (dolomite); shale; evaporite

Lockport Dolomite (Silurian) at surface, covers 12 % of this area

Lockport Dolomite - Dolomite, shades of white to medium gray, medium to massive bedded, fine to coarse crystalline; fossiliferous; vuggy.

Lithology: dolostone (dolomite)

Ohio Shale (Devonian) at surface, covers 10 % 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

Cincinnati Group as used by Wickstrom (1990) (Ordovician) at surface, covers 2 % of this area

Cincinnati Group as used by Wickstrom (1990) - Shale, dolomite and limestone, interbedded. Various shades of gray; thin to medium bedded; Data from core holes. Occurs beneath glacial drift.

Lithology: shale; dolostone (dolomite); limestone

Tymochtee and Greenfield Formations, Undivided (Silurian) at surface, covers 22 % 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.

Lithology: dolostone (dolomite); shale

Clinton and Cataract Groups, Undivided (Silurian) at surface, covers 5 % of this area

Clinton and Cataract Groups, Undivided - 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.

Lithology: shale; limestone; dolostone (dolomite)

Detroit River Group and Columbus Limestone, Undivided (Devonian) at surface, covers 10 % of this area

Detroit River Group and Columbus Limestone, Undivided - Dolomite, pale yellow-gray to light brown weather brown; thin to massive bedded; fine crystalline; local quartz sand in lower portion.

Lithology: dolostone (dolomite); sand