Geologic units in Warren county, New York

Charnockite, granitic and quartz syenite gneiss (Middle Proterozoic) at surface, covers 17 % 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.

Undivided metasedimentary rock and related migmatite (Middle Proterozoic) at surface, covers 13 % of this area

Undivided metasedimentary rock and related migmatite.

Biotite and/or hornblende granite gneiss (Middle Proterozoic) at surface, covers 12 % of this area

Locally pyroxenic; commonly with subordinate leucogranitic gneiss, biotite-quartz-plagioclase gneiss, other metasedimentary rocks, amphibolite, migmatite. Amphibolite with porphyroblasts of K-feldspar locally prominent in northwest Adirondacks. In northwest Adirondacks, grades into Yphg.

Biotite and/or hornblende granite gneiss (Middle Proterozoic) at surface, covers 12 % of this area

Locally pyroxenic; commonly with subordinate leucogranitic gneiss, biotite-quartz-plagioclase gneiss, other metasedimentary rocks, amphibolite, migmatite. Amphibolite with porphyroblasts of K-feldspar locally prominent in northwest Adirondacks. Overprint signifies inequigranular texture or phacoidal structure. In northwest Adirondacks, grades into Yphg.

Interlayered metasedimentary rock and granitic, charnockitic, mangeritic, or syenitic gneiss (Middle Proterozoic) at surface, covers 6 % of this area

Interlayered metasedimentary rock and granitic, charnockitic, mangeritic, or syenitic gneiss.

Glacial and Alluvial Deposits (Quaternary) at surface, covers 6 % of this area

Underlying bedrock geology unknown.

Interlayered metasedimentary rock and granitic, charnockitic, mangeritic, or syenitic gneiss (Middle Proterozoic) at surface, covers 5 % of this area

Interlayered metasedimentary rock and granitic, charnockitic, mangeritic, or syenitic gneiss.

Charnockite, granitic and quartz syenite gneiss (Middle Proterozoic) at surface, covers 5 % 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.

Metanorthosite and anorthositic gneiss (Middle Proterozoic) at surface, covers 4 % 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.

Biotite-quartz-plagioclase gneiss, amphibolite, and related migmatite (Middle Proterozoic) at surface, covers 3 % of this area

Locally sillimanitic; commonly garnetiferous in and adjacent to Adirondack Highlands.

Gabbroic or noritic metanorthosite (Middle Proterozoic) at surface, covers 3 % of this area

Dark mineral content in excess of 10 percent (part of unit Ya).

Hybrid rock: mangeritic to charnockitic gneiss (Middle Proterozoic) at surface, covers 2 % of this area

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

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

Undivided metasedimentary rock and related migmatite.

Biotite-quartz-plagioclase paragneiss (Middle Proterozoic) at surface, covers 2 % of this area

Commonly very low in biotite content, with interbedded feldspathic and biotitic quartzite and amphibolite; sillimanite and garnet common, graphite sporadic.

Charnockite, mangerite, pyroxene-quartz syenite gneiss (Middle Proterozoic) at surface, covers 1 % of this area

Overprint signifies inequigranular texture.

Leucogranitic gneiss (Middle Proterozoic) at surface, covers 1 % of this area

Sodic plagioclase ranges from generally subordinate to locally dominant; locally with biotite, hornblende, pyroxene, garnet, sillimanite, disseminated magnetite; commonly contains metasedimentary layers, amphibolite, migmatite; plagioclase-rich variety is host to magnetite ore bodies in eastern Adirondacks.

Biotite-quartz-plagioclase paragneiss, amphibolite, and related migmatite (Middle Proterozoic) at surface, covers 1 % of this area

Locally sillimanitic; commonly garnetiferous in and adjacent to Adirondack Highlands.

Beekmantown Group (in part) (Cambrian) at surface, covers 0.9 % of this area

In Champlain Valley: Whitehall Formation-dolostone, limestone (with Cryptozoon reefs); Ticonderoga Formation-dolostone (locally cherty), sandstone. In Vermont: Clarendon Springs Dolostone; Danby Formation-sandstone, quartzite, dolostone.

Glacial and Alluvial Deposits (Quaternary) at surface, covers 0.9 % of this area

Underlying bedrock geology unknown.

Calcitic and dolomitic marble (Middle Proterozoic) at surface, covers 0.8 % of this area

Predominantly; variably siliceous; in part with calcsilicate rock and amphibolite.

Quartzite, quartz-biotite schist and graphitic schist (Middle Proterozoic) at surface, covers 0.7 % of this area

In part feldspathic, micaceous, garnetiferous, sillimanitic.

Beekmantown Group (in part) (Lower Ordovician) at surface, covers 0.5 % 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.

Interlayered amphibolite and granitic, charnockitic, mangeritic, or syenitic gneiss (Middle Proterozoic) at surface, covers 0.5 % of this area

Interlayered amphibolite and granitic, charnockitic, mangeritic, or syenitic gneiss.

Metagabbro (Middle Proterozoic) at surface, covers 0.4 % of this area

Metagabbro, olivine metagabbro, derived amphibolite.

Leucogranitic (alaskitic) gneiss (Middle Proterozoic) at surface, covers 0.3 % of this area

Sodic plagioclase ranges from generally subordinate to locally dominant; locally with biotite, hornblende, pyroxene, garnet, sillimanite, disseminated magnetite; commonly contains metasedimentary layers, amphibolite, migmatite; plagioclase-rich variety is host to magnetite ore bodies in eastern Adirondacks.

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 central massif of Adirondacks.

Quartzite, quartz schist and graphitic schist (Middle Proterozoic) at surface, covers < 0.1 % of this area

In part feldspathic, micaceous, garnetiferous, sillimanitic.

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

Mangerite or charnockite, and the Yach lithology.

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

Potsdam Sandstone (Cambrian) at surface, covers < 0.1 % of this area

Potsdam Sandstone

Biotite and/or hornblende granite gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Locally pyroxenic; commonly with subordinate leucogranitic gneiss, biotite-quartz-plagioclase gneiss, other metasedimentary rocks, amphibolite, migmatite. Amphibolite with porphyroblasts of K-feldspar locally prominent in northwest Adirondacks. Overprint signifies inequigranular texture or phacoidal structure. In northwest Adirondacks, grades into Yphg.

Amphibolite (Middle Proterozoic) at surface, covers < 0.1 % of this area

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

Canajoharie Shale (Middle Ordovician) at surface, covers < 0.1 % of this area

Canajoharie Shale

Potsdam Sandstone (Cambrian) at surface, covers < 0.1 % of this area

Potsdam Sandstone (Covey Hill in Quebec)