Geologic units in Chautauqua county, New York

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

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.

Northeast Shale and Shumla Siltstone (Upper Devonian) at surface, covers 21 % of this area

Northeast Shale and Shumla Siltstone.

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

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.

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

Westfield Shale and Laona Siltstone.

Wiscoy Formation (Upper Devonian) at surface, covers 0.8 % of this area

Sandstone, shale; Hanover and Pipe Creek Shales.

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

Angola and Rhinestreet Shales.

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

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.

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

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

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

Medium-gray shale and some thin light-gray siltstone interbeds; included in Canadaway Formation of New York; included in ""Chemung"" of earlier workers; contains sparse fossil marine fauna.

Corry Sandstone through Riceville Formation, undivided (Devonian) at surface, covers < 0.1 % of this area

Same as Berea-through-Riceville (MDbr) interval, but uppermost sandstone unit is recognized as Corry, not Berea.

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

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.

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

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