Geologic units in Clinton county, New York

Potsdam Sandstone (Cambrian) at surface, covers 41 % of this area

Potsdam Sandstone (Covey Hill in Quebec)

Pyroxene and/or hornblende granitic gneiss (Middle Proterozoic) at surface, covers 23 % of this area

Biotitic in part; sodic plagioclase ranges from generally subordinate to locally dominant; plagioclase-rich facies locally contain disseminated magnetite and magnetite ore bodies; grades westward into Yhbg, and southward into Ylg.

Glacial and Alluvial Deposits (Quaternary) at surface, covers 11 % of this area

Underlying bedrock geology unknown.

Charnockite, granitic and quartz syenite gneiss (Middle Proterozoic) at surface, covers 7 % of this area

Variably leucocratic, containing varying amounts of hornblende, pyroxenes, biotite; may contain interlayered amphibolite, metasedimentary gneiss, migmatite. Overprint signifies inequigranular texture or phacoidal structure.

Beekmantown Group (in part) (Lower Ordovician) at surface, covers 6 % of this area

In St. Lawrence Valley: Ogdensburg Dolostone (Beauharnois Dolostone in Canada); In Champlain Valley: Providence Island Dolostone; Fort Cassin Formation-limestone, dolostone; Fort Ann Formation (Spellman of Clinton and Essex Counties)-limestone, dolostone; Cutting Formation-dolostone (locally cherty), limestone, siltstone. In Vermont: includes Bridport, Bascom, Cutting, and Shelburne carbonates.

Theresa Formation (Cambrian - Lower Ordovician) at surface, covers 4 % of this area

Dolostone, sandstone (Chateauguay in Quebec).

Valcour, Crown Point, and Day Point Limestones (Middle Ordovician) at surface, covers 2 % of this area

Locally reefy, Ste. Therese Siltstone at base; Middlebury Limestone in Vermont; St. Martin and Rockcliffe Limestones in St. Lawrence Valley. Includes some Otbr and Obk adjacent to Champlain Thrust in Vermont.

Metanorthosite and anorthositic gneiss (Middle Proterozoic) at surface, covers 2 % of this area

Mafic mineral percentage contoured in northwestern Marcy massif (St. Regis Quadrangle); contour value shown on high side of countoue line. See also Yach, Yack, Yamu.

Undivided metasedimentary rock and related migmatite (Middle Proterozoic) at surface, covers 2 % of this area

Undivided metasedimentary rock and related migmatite.

Cumberland Head Argillite (Middle Ordovician) at surface, covers 1 % of this area

Cumberland Head Argillite

Trenton Group (Middle Ordovician) at surface, covers 0.8 % of this area

In Black River Valley: Cobourg Formation-Hillier shale and limestone Member, Hallowell limestone Member; Denley, Sugar River, Kings Falls, and Rockland Limestones. In Champlain Valley: Glens Falls Formation-Montreal shale and limestone Member, Larrabee limestone Member.

Charnockite, mangerite, pyroxene-quartz syenite gneiss (Middle Proterozoic) at surface, covers 0.7 % of this area

Overprint signifies inequigranular texture.

Stony Point Shale (Middle Ordovician) at surface, covers 0.4 % of this area

Stony Point Shale

Black River Group (Middle Ordovician) at surface, covers 0.3 % of this area

In Black River Valley: Chaumont Limestone-locally cherty; Lowville Limestone; Pamelia Formation-dolostone, shale, arkose. In Champlain Valley: Amsterdam, Isle La Motte, and Lowville Limestones: Pamelia Dolostone.

Metagabbro (Middle Proterozoic) at surface, covers 0.2 % of this area

Metagabbro, olivine metagabbro, derived amphibolite.

Amphibolite (Middle Proterozoic) at surface, covers 0.2 % of this area

Commonly biotitic; garnetiferous, pyroxenic, in and adjacent to Adirondack Highlands.

Ferrohedenbergite-fayalite granite and granite gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Ferrohedenbergite-fayalite granite and granite gneiss.

Interlayered gabbroic or noritic metanorthosite (Middle Proterozoic) at surface, covers < 0.1 % of this area

Mangerite or charnockite, and the Yach lithology.

Hybrid rock: mangeritic to charnockitic gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

With xenocrysts of calcic andesine and, locally, xenoliths of anorthosite; with increasing percentage of anorthosite component, passes gradationally into anorthositic rocks.

Trenton and Black River Groups, undivided (Middle Ordovician) at surface, covers < 0.1 % of this area

Glens Falls and Orwell Limestones. In Canada: Lindsay, Verulam, Bodcaygeon, Gull River Limestones; Shadow Lake Dolostone.