Geologic units in Montgomery county, New York

Utica Shale (Middle Ordovician) at surface, covers 29 % of this area

Utica Shale

Canajoharie Shale (Middle Ordovician) at surface, covers 23 % of this area

Canajoharie Shale

Schenectady Formation (Upper Ordovician) at surface, covers 17 % of this area

Graywacke, sandstone, siltstone, shale.

Beekmantown Group (Lower Ordovician) at surface, covers 10 % 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.

Beekmantown Group (Cambrian) at surface, covers 6 % of this area

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

Trenton and Black River Groups, undivided (Middle Ordovician) at surface, covers 5 % 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.

Frankfort Formation (Upper Ordovician) at surface, covers 4 % of this area

Shale, siltstone.

Glacial and Alluvial Deposits (Quaternary) at surface, covers 2 % of this area

Underlying bedrock geology unknown.

Theresa (Galway) Formation (Cambrian) at surface, covers 0.7 % of this area

Dolostone, sandstone, shale.

Undivided metasedimentary rock and related migmatite (Middle Proterozoic) at surface, covers 0.5 % of this area

Undivided metasedimentary rock and related migmatite.

Utica Shale (Middle Ordovician) at surface, covers 0.5 % of this area

Utica Shale

Potsdam Sandstone (Cambrian) at surface, covers 0.3 % of this area

Potsdam Sandstone

Quartz-feldspar gneiss (Middle Proterozoic) at surface, covers 0.2 % of this area

With variable amounts of garnet, sillimanite, biotite.

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

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

Clinton Group (Silurian) at surface, covers < 0.1 % of this area

Herkimer Sandstone including Joslin Hill and Jordanville Members; Kirkland Hematite; Willowvale Shale; Westmoreland Hematite; Sauquoit Formation-sandstone, shale; Otsquago Sandstone; Oneida Conglomerate.

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.