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Geologic units in Chautauqua county, New York

Conneaut Group, undivided (Upper Devonian) at surface, covers 51 % of this area

Conneaut Group, undivided - In west: Ellicott and Dexterville Formations-shale, siltstone. In east: Germania Formation-shale, sandstone; Whitesville Formation-shale, sandstone; Hinsdale Sandstone; Wellsville Formation-shale, sandstone; Cuba Sandstone.

Lithology: shale; sandstone; siltstone

Northeast Shale and Shumla Siltstone (Upper Devonian) at surface, covers 20 % of this area

Northeast Shale and Shumla Siltstone.

Lithology: shale; siltstone

Oswayo and Venango Formations (Upper Devonian) at surface, covers 16 % of this area

Oswayo and Venango Formations - shale, siltstone, sandstone; replaced eastwardly by Cattaraugus Formation-shale, sandstone, conglomerate.

Gowanda, South Wales, and Dunkirk Shales (Upper Devonian) at surface, covers 7 % of this area

Gowanda, South Wales, and Dunkirk Shales.

Lithology: shale

Westfield Shale and Laona Siltstone (Upper Devonian) at surface, covers 4 % of this area

Westfield Shale and Laona Siltstone.

Lithology: shale; siltstone

Angola and Rhinestreet Shales (Upper Devonian) at surface, covers 0.1 % of this area

Angola and Rhinestreet Shales.

Lithology: shale; black shale

Venango Formation (Devonian) at surface, covers < 0.1 % of this area

Venango Formation - Light-gray siltstone interbedded with some flaggy, gray sandstone and some bluish-gray shale; Panama Conglomerate and Woodcock Sandstone are, respectively, the lower and upper key beds defining the formation; referred to as "Cattaraugus" by some workers; includes some red shales where it interfingers to the east and south with the Catskill Formation; marine fossils present.

Cuyahoga and Knapp Formations (Lower Mississippian) at surface, covers < 0.1 % of this area

Cuyahoga and Knapp Formations - Cuyahoga Formation-shale, sandstone; Corry Sandstone; Knapp Formation-shale, conglomerate 60-100 ft. (20-30 m).

Wiscoy Formation (Upper Devonian) at surface, covers < 0.1 % of this area

Wiscoy Formation - sandstone, shale; Hanover and Pipe Creek Shales.

Chadakoin Formation (Devonian) at surface, covers < 0.1 % of this area

Chadakoin Formation - Light-gray or brownish siltstone and some sandstone, interbedded with medium-gray shale; included in Conneaut Group and "Chemung" of earlier workers; marine fossils common; includes "pink rock" of drillers.

Lithology: siltstone; shale; sandstone

Shenango Formation through Riceville Formation, undivided (Mississippian and Devonian) at surface, covers < 0.1 % of this area

Shenango Formation through Riceville Formation, undivided - Sandstone, siltstone, and shale in varying proportions; distinguished from Shenango-through-Oswayo (MDso) interval on basis of more common gray shale in Riceville as compared with olive-colored shale and sandstone of Oswayo; contains marine fossils.

Lithology: sandstone; siltstone; shale

Girard Shale (Devonian) at surface, covers < 0.1 % of this area

Girard Shale - Argillaceous, ashen-gray, flaky shale and siltstone; included in Conneaut Group and "Chemung" of earlier workers; marine fossils rare.

Lithology: shale; siltstone