Geologic units in Schenectady county, New York

Schenectady Formation (Upper Ordovician) at surface, covers 79 % of this area

Graywacke, sandstone, siltstone, shale.

Canajoharie Shale (Middle Ordovician) at surface, covers 10 % of this area

Canajoharie Shale

Normanskill Shale (Middle Ordovician) at surface, covers 9 % of this area

Minor mudstone, sandstone.

Beekmantown Group (Lower Ordovician) at surface, covers 2 % of this area

Mohawk Valley: Chuctanunda Creek Dolostone; Tribes Hill Formation-limestone, dolostaone; Gailor Dolostone. Washington County: Providence Island Dolostone; Fort Cassin Formation-limestone, dolostone; Fort Ann Formation-limestone, dolostone; Cutting Formation-dolostone, local chert, limestone at top, siltstone at base.

Trenton and Black River Groups, undivided (Middle Ordovician) at surface, covers 0.3 % of this area

Mohawk Valley: Dolgeville, Denley, Sugar River, Kings Falls, Glens Falls, Rockland, Amsterdam, and Lowville Limestones. Washington County: Glens Falls and Orwell Limestones.

Helderberg Group (Lower Devonian) at surface, covers < 0.1 % of this area

West of Albany: Alsen, Becraft, New Scotland, Kalkberg, Coeymans, and Manlius Limestones; Rondout Dolostone. South of Albany: Port Ewen, Alsen thru Manlius Limestones; Rondout Dolostone.

Beekmantown Group (Cambrian) at surface, covers < 0.1 % of this area

Mohawk Valley: Little Falls Dolostone-chert; Hoyt Formation-limestone, dolostone, oolite. Washington county: Whitehall Formation-dolostone, limestone; Ticonderoga Dolostone-chert.

Cobleskill Limestone (Upper Silurian) at surface, covers < 0.1 % of this area

Bertie, Camillus, and Syracuse Formations - shale, dolostone; Brayman Shale.