Geologic units in New York (state in United States)

Additional scientific data in this geographic area

Machias Formation (Upper Devonian) at surface, covers 4 % of this area

Shale, siltstone; Rushford Sandstone; Caneadea, Canisteo, and Hume Shales; Canaseraga Sandstone; South Wales and Dunkirk Shales.

Conneaut Group, undivided (Upper Devonian) at surface, covers 4 % 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.

Upper Walton Formation (Upper Devonian) at surface, covers 3 % of this area

Shale, sandstone, conglomerate.

Genesee Group (Upper Devonian) at surface, covers 3 % of this area

West River Shale; Genundewa Limestone; Penn Yan and Geneseo Shales; all except Geneseo replaced eastwardly by Ithaca Formation-shale, siltstone and Sherburne Siltstone.

Biotite and/or hornblende granite gneiss (Middle Proterozoic) at surface, covers 3 % 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.

Metanorthosite and anorthositic gneiss (Middle Proterozoic) at surface, covers 3 % 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.

Charnockite, granitic and quartz syenite gneiss (Middle Proterozoic) at surface, covers 3 % 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.

Monmouth Group, Matawan Group and Magothy Formation (Upper Cretaceous) at surface, covers 2 % of this area

Silty clay, glauconitic sandy clay, sand, gravel.

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

Underlying bedrock geology unknown.

Oneonta Formation (Middle - Upper Devonian) at surface, covers 2 % of this area

Shale, sandstone, conglomerate.

Sonyea Group (Upper Devonian) at surface, covers 2 % of this area

In west: Cashaqua and Middlesex Shales. In east: Rye Point Shale; Rock Stream ("Enfield") Siltstone; Pulteney, Sawmill Creek, Johns Creek, and Montour Shales.

Potsdam Sandstone (Cambrian) at surface, covers 2 % of this area

Potsdam Sandstone (Covey Hill in Quebec)

Interlayered metasedimentary rock and granitic, charnockitic, mangeritic, or syenitic gneiss (Middle Proterozoic) at surface, covers 2 % of this area

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

Lower Walton Formation (Upper Devonian) at surface, covers 2 % of this area

Shale, sandstone, conglomerate.

Beekmantown Group (in part) (Lower Ordovician) at surface, covers 2 % 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.

Undivided metasedimentary rock and related migmatite (Middle Proterozoic) at surface, covers 1 % of this area

Undivided metasedimentary rock and related migmatite.

Queenston Shale (Upper Ordovician) at surface, covers 1 % of this area

Queenston Shale

Oswego Sandstone (Upper Ordovician) at surface, covers 1 % of this area

Oswego Sandstone

Canajoharie Shale (Middle Ordovician) at surface, covers 1 % of this area

Canajoharie Shale

Vernon Formation (Upper Silurian) at surface, covers 1 % of this area

Dhale, dolostone.

Trenton Group (Middle Ordovician) at surface, covers 1 % 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.

Utica Shale (Middle Ordovician) at surface, covers 1 % of this area

Utica Shale

Pulaski and Whetstone Gulf Formations (Upper Ordovician) at surface, covers 1 % of this area

Siltstone, shale.

Camillus, Syracuse, and Vernon Formations (Upper Silurian) at surface, covers 1 % of this area

Shale, dolostone, salt, and gypsum.

Beers Hill, Dunn Hill, Millport, and Moreland Shales; Grimes Siltstone (Upper Devonian) at surface, covers 1 % of this area

Beers Hill, Dunn Hill, Millport, and Moreland Shales; Grimes Siltstone.

Gardeau Formation (Upper Devonian) at surface, covers 1 % of this area

Shale, siltstone; Roricks Glen Shale.

Theresa Formation (Cambrian - Lower Ordovician) at surface, covers 1 % of this area

Dolostone, sandstone (Chateauguay in Quebec).

Undifferentiated Medina Group and Queenston Formation (Upper Ordovician - Lower Silurian) at surface, covers 1 % of this area

Grimsby Formation-sandstones, shale; and Queenston Formation-shale, siltstone.

Panther Mountain Formation (Middle Devonian) at surface, covers 1 % of this area

Shale, siltstone, sandstone.

Oswayo and Venango Formations (Upper Devonian) at surface, covers 1.0 % of this area

Shale, siltstone, sandstone; replaced eastwardly by Cattaraugus Formation-shale, sandstone, conglomerate.

Clinton Group (Lower Silurian) at surface, covers 1.0 % of this area

Herkimer Sandstone; Kirkland Hematite; Willowvale Shale; Westmoreland Hematite; Sauquoit Formation-sandstone, shale; Oneida Conglomerate.

Unadilla, Laurens, New Lisbon, and Gilboa Formations (Middle Devonian) at surface, covers 1.0 % of this area

Shale, siltstone, sandstone.

Biotite and/or hornblende granite gneiss (Middle Proterozoic) at surface, covers 0.9 % 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.

Normanskill Formation (Middle Ordovician) at surface, covers 0.9 % of this area

Shale, argillite, siltstone.

Wiscoy Formation (Upper Devonian) at surface, covers 0.9 % of this area

Sandstone, shale; Hanover and Pipe Creek Shales.

West Hill and Gardeau Formations (Upper Devonian) at surface, covers 0.9 % of this area

Shale, siltstone; Roricks Glen Shale; upper Beers Hill Shale; Grimes Siltstone.

Pyroxene and/or hornblende granitic gneiss (Middle Proterozoic) at surface, covers 0.8 % 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.

Schenectady Formation (Upper Ordovician) at surface, covers 0.8 % of this area

Graywacke, sandstone, siltstone, shale.

Charnockite, mangerite, pyroxene-quartz syenite gneiss (Middle Proterozoic) at surface, covers 0.8 % of this area

Overprint signifies inequigranular texture.

Lockport Group (Upper Silurian) at surface, covers 0.8 % of this area

Oak Orchard and Penfield Dolostones; both replaced eastwardly by Sconondoa Formation-limestone, dolostone.

Glacial and Alluvial Deposits (Quaternary) at surface, covers 0.8 % of this area

Underlying bedrock geology unknown.

Leucogranitic (alaskitic) gneiss (Middle Proterozoic) at surface, covers 0.7 % 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.

Moscow Formation (Middle Devonian) at surface, covers 0.7 % of this area

In west: Cooperstown and Portland Point shale and sandstone Members; In east: ""Manorkill"" and Portland Point shale and sandstone Members.

Calcitic and dolomitic marble (Middle Proterozoic) at surface, covers 0.7 % of this area

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

Austin Glen Formation (Middle Ordovician) at surface, covers 0.7 % of this area

Graywacke, shale

Plattekill and Ashokan Formations (Middle Devonian) at surface, covers 0.7 % of this area

Shale, sandstone; Ashokan Formation-shale, sandstone.

Angola and Rhinestreet Shales (Upper Devonian) at surface, covers 0.7 % of this area

Angola and Rhinestreet Shales.

Skaneateles Formation (Middle Devonian) at surface, covers 0.7 % of this area

In west: Levanna Shale and Stafford Limestone Members; In east: Butternut, Pompey, and Delphi Station Shale Members, Mottville Sandstone Member.

Ludlowville Formation (Middle Devonian) at surface, covers 0.7 % of this area

In west: Deep Run Shale, Tichenor Limestone, Wanakah and Ledyard Shales, Centerfield Limestone Members. In east: King Ferry Shale and other members, Stone Mill Sandstone Member.

Camillus and Syracuse Formations (Upper Silurian) at surface, covers 0.6 % of this area

Shale, dolostone, gypsum, salt.

Black River Group (Middle Ordovician) at surface, covers 0.6 % 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.

Honesdale Formation (Upper Devonian) at surface, covers 0.6 % of this area

Sandstone, shale.

Marcellus Formation (Middle Devonian) at surface, covers 0.6 % of this area

Pecksport, Solsville, Otsego, and Chittenango shale and sandstone Members, Cherry Valley Limestone, and Union Springs Shale Members.

Lockport Group (Upper Silurian) at surface, covers 0.6 % of this area

Consists of: Guelph, Oak Orchard, Eramosa, and Goat Island Dolostones; Gasport Limestone-local bioherms.

Austin Glen Formation (Middle Ordovician) at surface, covers 0.6 % of this area

Graywacke, shale

Northeast Shale and Shumla Siltstone (Upper Devonian) at surface, covers 0.6 % of this area

Northeast Shale and Shumla Siltstone.

Nassau Formation (Cambrian?) at surface, covers 0.5 % of this area

South of 43 degrees; slate, shale, thin quartzite, includes Stuyvesant Conglomerate, Diamond Rock Quartzite, Curtis Mountain Quartzite, and Bomoseen Graywacke Members.

Skaneateles Formation (Middle Devonian) at surface, covers 0.5 % of this area

Levanna Shale, Stafford Limestone Members.

Biotite-quartz-plagioclase paragneiss, amphibolite, and related migmatite (Middle Proterozoic) at surface, covers 0.5 % of this area

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

Undifferentiated Lower Hamilton Group (Middle Devonian) at surface, covers 0.5 % of this area

Panther Mountain, Mount Marion, Stony Hollow, and Union Springs shales and sandstones.

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.

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

Undivided metasedimentary rock and related migmatite.

Moscow Formation (Middle Devonian) at surface, covers 0.5 % of this area

In west: Windom and Kashong Shales, Menteth Limestone Members; In east: Cooperstown Shale Member, Portland Point Limestone Member.

Onondaga and Bois Blanc Limestones (Middle Devonian) at surface, covers 0.5 % of this area

In New York: Onondaga Limestone-Seneca, Morehouse (cherty), and Clarence Limestone Members, Edgecliff cherty Limestone Member, local coral bioherms; Bois Blanc Limestone-sandy, thin, discontinous. In Ontario: Dundee Limestone; Lucas Formation-dolostone, limestone (Anderdon); Amherstburg Formation-limestone, dolostone, sandstone (Sylvania); Bois Blanc Formation-dolostone, limestone, sandstone (Springvale).

Marcellus Formation (Middle Devonian) at surface, covers 0.4 % of this area

In west: Oatka Creek Shale Member; In east: Cardiff and Chittenango Shale Members, Cherry Vale Limestone and Union Springs Shale Members.

Mangerite, pyroxene-(hornblende) syenite gneiss (Middle Proterozoic) at surface, covers 0.4 % of this area

Mangerite, pyroxene syenite gneiss - pyroxene-(hornblende) syenitic gneiss; mesoperthite common. Overprint signifies inequigranular texture.

Walloomsac Formation (Middle Ordovician) at surface, covers 0.4 % of this area

Slate, phyllite, schist, metagraywacke.

Nunda Formation, West Hill Formation (Upper Devonian) at surface, covers 0.4 % of this area

Nunda: sandstone, shale; West Hill: shale, siltstone; Corning Shale.

Helderberg Group (Lower Devonian) at surface, covers 0.4 % 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.

Akron Dolostone (Upper Silurian) at surface, covers 0.3 % of this area

Bertie Formation - dolostone, shale.

Slide Mountain Formation (Upper Devonian) at surface, covers 0.3 % of this area

Sandstone, shale, conglomerate.

Frankfort Formation (Upper Ordovician) at surface, covers 0.3 % of this area

Shale, siltstone.

Normanskill Shale (Middle Ordovician) at surface, covers 0.3 % of this area

Minor mudstone, sandstone.

Onondaga Limestone (Middle Devonian) at surface, covers 0.3 % of this area

Seneca, Morehouse (cherty), and Nedrow Limestone Members, Edgecliff cherty Limestone Member, local bioherms.

Slide Mountain Formation (Upper Devonian) at surface, covers 0.3 % of this area

Sandstone, shale, conglomerate.

Charnockite, granitic and quartz syenite gneiss (Middle Proterozoic) at surface, covers 0.3 % 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.

Interlayered metasedimentary rock and granitic, charnockitic, mangeritic, or syenitic gneiss (Middle Proterozoic) at surface, covers 0.3 % of this area

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

Onondaga Limestone (Lower to Middle Devonian) at surface, covers 0.3 % of this area

Schoharie Formation-shale, limestone; Carlisle Center Siltstone; Esopus Shale.

Biotite and/or hornblende granite gneiss (Middle Proterozoic) at surface, covers 0.3 % 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.

Ludlowville Formation (Middle Devonian) at surface, covers 0.3 % of this area

Deep Run Shale, Tichenor Limestone, Wanakah and Ledyard Shales, Centerfield Limestone Members.

Wappinger Group (Cambrian - Lower Ordovician) at surface, covers 0.3 % of this area

(Including Fishkill limestone and dolostone): Copake Formation ?-limestone, dolostone; Rochdale Formation-limestone, dolostone; Halcyon Lake Dolostone-locally cherty; Briarcliff Dolostone; Pine Plains Formation-dolostone, shale, oolite; Stissing Formation-dolostone, shale.

Walloomsac Formation (Middle Ordovician) at surface, covers 0.3 % of this area

Phyllite, schist, metagraywacke.

Manhattan Formation, undivided (Ordovician?) at surface, covers 0.3 % of this area

Pelitic schists, amphibolite; Units ?Omb, ?Omc, and ?Omd may be Cambrian eugeosynclinal rocks thrust upon Oma; ?Omd - sillimanite-garnet-muscovite-biotite-plagioclase-quartz gneiss; ?Omc - sillimanite-garnet-muscovite-biotite-quartz-plagioclase schistose gneiss, sillimanite nodules, local quartz-rich layers; ?Omb - discontinous unit of amphibolite and ?Omc-type schist.

Biotite-quartz-plagioclase gneiss (Middle Proterozoic) at surface, covers 0.3 % of this area

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

Nunda Formation (Upper Devonian) at surface, covers 0.3 % of this area

Sandstone, shale.

Rensselaer Graywacke (Cambrian?) at surface, covers 0.3 % of this area

Minor shale.

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

With variable amounts of garnet, sillimanite, biotite.

Fordham Gneiss, undivided (Precambrian - Middle Proterozoic) at surface, covers 0.2 % of this area

fe: garnet-biotite-quartz-plagioclase gneiss, and amphibolite; fd: sillimanite-garnet schistose gneiss, quartzite; fc: biotite-hornblende-quartz-plagioclase gneiss, quartz-feldspar lenses, amphibolite, biotite and/or hornblende-quartz-feldspar gneiss; fb: amphibolite, biotite and/or hornblende-garnet-quartz-plagioclase gneiss; fa: garnet-biotite-quartz-plagioclase gneiss, amphibolite, biotite-hornblende-quartz-plagioclase gneiss, quartz-feldspar granulite.

Cashaqua and Middlesex Shales (Upper Devonian) at surface, covers 0.2 % of this area

Cashaqua and Middlesex Shales.

Moscow Formation (Middle Devonian) at surface, covers 0.2 % of this area

Windom and Kashong Shales, Menteth Limestone Members.

Mount Merino and Indian River Formations (Ordovician) at surface, covers 0.2 % of this area

Shale, slate, cherts.

Beekmantown Group (Cambrian) at surface, covers 0.2 % of this area

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

Elizaville Formation (Cambrian - Ordovician) at surface, covers 0.2 % of this area

Shale, argillite, quartzite.

Trenton and Black River Groups, undivided (Middle Ordovician) at surface, covers 0.2 % 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.

Tully Limestone (Middle Devonian) at surface, covers 0.2 % of this area

Tully Limestone

Hornblende granite and granite gneiss (Middle Proterozoic) at surface, covers 0.2 % of this area

With subordinate leucogranite.

Hybrid rock: mangeritic to charnockitic gneiss (Middle Proterozoic) at surface, covers 0.2 % of this area

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

Poultney Formation (Middle and Lower Ordovician) at surface, covers 0.2 % of this area

Dull-white and whitish-gray-weathering, and pale-green and gray, thinly bedded to laminated slate and phyllite. Has distinctive beds, 1 cm to several centimeters thick, of siliceous argillite and metasiltstone and locally abundant thin beds of micritic black limestone near the base, interbedded with dark slate. Contains graptolites ranging from Ibexian to Whiterockian (Berry, 1961). Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

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

Metagabbro, olivine metagabbro, derived amphibolite.

Biotite granite gneiss (Middle Proterozoic) at surface, covers 0.2 % of this area

Overprint signifies inequigranular texture.

Cobleskill Limestone (Upper Silurian) at surface, covers 0.2 % of this area

Bertie and Camillus Formations - dolostone, shale.

Biotite-quartz-plagioclase gneiss (Middle Proterozoic) at surface, covers 0.2 % of this area

With subordinate biotite granitic gneiss, amphibolite, calcsilicate rock.

Beekmantown Group (Lower Ordovician) at surface, covers 0.2 % 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.

Gowanda, South Wales, and Dunkirk Shales (Upper Devonian) at surface, covers 0.2 % of this area

Gowanda, South Wales, and Dunkirk Shales.

Lower Beers Hill Shale (Upper Devonian) at surface, covers 0.2 % of this area

Dunn Hill, Millport, and Moreland Shales.

Irondequoit Limestone thru Kodak Sandstone (Lower Silurian) at surface, covers 0.2 % of this area

Includes: Irondequoit Limestone, Williamson Shale; Wolcott Furnace Hematite; Wolcott Limestone; Sodus Shale; Bear Creek Shale; Wallington Limestone; Furnaceville Hematite; Maplewood Shale; Kodak Sandstone.

Dolomitic and calcitic marbles interlayered with significant amounts of calcsilicate rock (Middle Proterozoic) at surface, covers 0.2 % of this area

Metasedimentary amphibolite, pyroxene granulite, and various gneisses; includes interlayered diopsidic and tremolitic marble and quartzite, and talc-tremolite rock (mined in Balmat-Edwards belt, northwest Adirondacks).

Bloomsburg Formation (Upper Silurian) at surface, covers 0.2 % of this area

Shale, sandstone; Guymard Quartzite; Otisville Shale; Shawangunk Conglomerate-sandstone, conglomerate.

Raritan Formation (Upper Cretaceous) at surface, covers 0.2 % of this area

Clay, silty clay, sand, gravel.

Decew Dolostone and Rochester Shale (Lower Silurian) at surface, covers 0.2 % of this area

Decew Dolostone and Rochester Shale

Undifferentiated Hamilton Group (Middle Devonian) at surface, covers 0.2 % of this area

Shale, siltstone. In eastern Orange County: Skunnemunk Formation-sandstone, conglomerate; Bellvale Formation-shale, sandstone; Cornwall Shale.

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

Pyroxenic amphibolite, hornblende gneiss, commonly biotitic, garnetiferous; subordinate calcsilicate rock.

Stockbridge Marble (Cambrian - Lower Ordovician) at surface, covers 0.2 % of this area

Stockbridge Marble.

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

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

Germantown Formation (Cambrian) at surface, covers 0.1 % of this area

South of Troy; shale, conglomerate, limestone.

Theresa (Galway) Formation (Cambrian) at surface, covers 0.1 % of this area

Dolostone, sandstone, shale.

Charnockite, mangerite, pyroxene-quartz syenite gneiss (Middle Proterozoic) at surface, covers 0.1 % of this area

Overprint signifies inequigranular texture.

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

Sandstone, shale.

Hornblende-quartz syenite gneiss (Middle Proterozoic) at surface, covers 0.1 % of this area

Overprint signifies inequigranular texture.

Everett Schist (Cambrian?) at surface, covers 0.1 % of this area

Locally with minor meta-graywacke lenses.

Medina Group (Lower Silurian) at surface, covers 0.1 % of this area

Consists of: Thorold Sandstone; Grimsby Formation-sandstone, shale; Power Glen and Cabot Head Shales; Whirlpool Sandstone.

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

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

Genesee Group (Upper Devonian) at surface, covers 0.1 % of this area

West River Shale; Genundewa Limestone; Penn Yan and Geneseo Shales; North Evans Limestone.

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

Utica 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.

Syracuse Formation (Upper Silurian) at surface, covers 0.1 % of this area

Dolostone, shale, gypsum, salt.

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

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

Quartz-plagioclase gneiss (Middle Proterozoic) at surface, covers 0.1 % of this area

May contain pyroxenes, hornblende, biotite; locally interlayered with amphibolite; subordinate biotite mesoperthite gneiss.

Pulaski and Whetstone Gulf Formations (Upper Ordovician) at surface, covers 0.1 % of this area

Shale, siltstone.

Valcour, Crown Point, and Day Point Limestones (Middle Ordovician) at surface, covers 0.1 % 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.

Austerlitz Phyllite (Cambrian?) at surface, covers 0.1 % of this area

Austerlitz Phyllite - minor quartzite

Inwood Marble (Early Cambrian - Lower Ordovician) at surface, covers 0.1 % of this area

Dolomite marble, calc-schist, granulite, and quartzite, overlain by calcite marble; grades into underlying patchy Lowerre Quartzite of Early Cambrian age.

Bull Formation - Mettawee slate facies (Neoproterozoic) at surface, covers 0.1 % of this area

Predominantly greenish-gray to pale-lustrous-green chlorite-muscovite-quartz phyllite; and green and purple, bedded and mottled phyllite. Locally contains boudins and thin beds of limestone and pods of pinkish-gray to cream-white dolostone, and minor quartzite. Unit interfingers with the West Castleton Formation above and laterally grades into the Bomoseen Graywacke Member. Also shown as CZnm (Mettawee Member of the Nassau Formation of Potter, 1972). Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

Stuyvesant Falls Formation (Ordovician) at surface, covers 0.1 % of this area

South of Troy; shale, siltstone.

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

Oatka Creek Shale Member.

Biotite-quartz-plagioclase gneiss, amphibolite, and related migmatite (Middle Proterozoic) at surface, covers 0.1 % of this area

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

Quartz-feldspar gneiss (Middle Proterozoic) at surface, covers 0.1 % of this area

With variable amounts of garnet, sillimanite, biotite.

Fordham Gneiss (C and D member) (Precambrian - Middle Proterozoic) at surface, covers 0.1 % of this area

fc: biotite-hornblende-quartz-plagioclase gneiss, quartz-feldspar lenses, amphibolite, biotite and/or hornblende-quartz-feldspar gneiss; fd: sillimanite-garnet schistose gneiss, quartzite.

Netop Formation - chlorite phyllite member (Cambrian and Neoproterozoic) at surface, covers < 0.1 % of this area

Light-green to gray, lustrous, chlorite±chloritoid-muscovite-quartz phyllite and greenish-gray metasiltstone. Rocks of the Dorset Mountain slice (includes Dorset Mountain proper and Mount Equinox, southward to West Mountain near Bennington). Part of the Taconic Allochthon.

Onondaga Limestone (Lower to Middle Devonian) at surface, covers < 0.1 % of this area

Seneca, Morehouse (cherty), and Nedrow Limestone Members, Edgecliff cherty Limestone Member, local bioherms, Buttermilk Falls Limestone Member; Schoharie Formation-shale, limestone; Carlisle Center Siltstone; Esopus Shale.

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

In part feldspathic, micaceous, garnetiferous, sillimanitic.

Hartland Formation (Ordovician?) at surface, covers < 0.1 % of this area

Basal amphibolite overlain by pelitic schists.

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

Coeymans and Manlius Limestones; Rondout Dolostone.

Brunswick Formation (Upper Triassic) at surface, covers < 0.1 % of this area

Sandstone and conglomerate.

Glacial and Alluvial Deposits (Quaternary) at surface, covers < 0.1 % of this area

Underlying bedrock geology unknown.

West Castleton Formation (Middle and Lower Cambrian) at surface, covers < 0.1 % of this area

Dark-gray to black, fine-grained slate and phyllite, interbedded with thinly laminated bluish-black fine-grained limestone, limestone conglomerate. Unit is interbedded near the base with green phyllite and sooty-punky-weathering calcitic quartz wacke and limestone of the Browns Pond Formation, which is shown separately where mapped. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

Undifferentiated Middle Ordovician thru Lower Cambrian allochthonous rocks (Cambrian - Ordovician) at surface, covers < 0.1 % of this area

Principally pelite; lesser quartzite, limestone, conglomerate, graywacke.

Westfield Shale and Laona Siltstone (Upper Devonian) at surface, covers < 0.1 % of this area

Westfield Shale and Laona Siltstone.

Bull Formation - Bomoseen Graywacke member (Neoproterozoic) at surface, covers < 0.1 % of this area

Pale-reddish-brown to light-gray-weathering, medium- and fine-grained, massive to thickly bedded, olive-green to gray micaceous quartz-feldspar graywacke and siltstone, locally containing coarse detrital muscovite, biotite, and autoclastic slate chips. Resembles finer grained parts of the Rensselaer Graywacke Member of the Nassau Formation (of Potter, 1972), and the Bird Mountain Grit (of Dale, 1900). Unit interfingers with and grades laterally into the Mettawee slate facies. In the Mt. Anthony area is shown as CZnb (Bomoseen Member of the Nassau Formation of Potter, 1972). Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

Decew Dolostone and Rochester Shale (Lower Silurian) at surface, covers < 0.1 % of this area

Decew Dolostone and Rochester Shale

Hybrid rock: anorthositic and metasedimentary rock (Middle Proterozoic) at surface, covers < 0.1 % of this area

Ranges from anorthositic rock with local blocks, shreds or layers of undifferentiated metasediment, to mappable roof pendants and/or xenoliths of metasediment in anorthositic rock.

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

Sandstone, shale; Hanover and Pipe Creek Shales.

Biotite-quartz-plagioclase paragneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

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

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

In part feldspathic, micaceous, garnetiferous, sillimanitic.

Nassau Formation of Potter (1972) - Mettawee member (Neoproterozoic) at surface, covers < 0.1 % of this area

Predominantly greenish-gray to pale-lustrous-green chlorite-muscovite-quartz phyllite; and green and purple, bedded and mottled phyllite. Locally contains boudins and thin beds of limestone and pods of pinkish-gray to cream-white dolostone, and minor quartzite. Unit interfingers with the West Castleton Formation above and laterally grades into the Bomoseen Graywacke Member. Also shown as CZnm (Mettawee Member of the Nassau Formation of Potter, 1972). Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

Irondequoit Limestone thru Kodak Sandstone (Lower Silurian) at surface, covers < 0.1 % of this area

Includes: Irondequoit Limestone, Rockway Dolostone, Hickory Corners Limestone, Neahga Shale, and Kodak Sandstone.

Walloomsac Formation (Upper Ordovician) at surface, covers < 0.1 % of this area

Same description as Hortonville Formation - Dark-gray siliceous shale and phyllite containing thin beds of bluish-gray argillaceous limestone and minor beds of gray to tan quartzite. Grades into limy shales of the Stony Point Formation. Tectonically shredded, silty varieties near and on Whipstock Hill constitute the Whipstock Breccia Member of Potter (1972) (Oww). Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

Vernon Shale (Upper Silurian) at surface, covers < 0.1 % of this area

Vernon Shale

Garnet-bearing gneiss and interlayered quartzite (Middle Proterozoic) at surface, covers < 0.1 % of this area

Contains varying amounts of biotite, garnet, sillimanite; minor marble, amphibolite, rusty paragneiss.

Poultney Formation (""A"" Member) (Cambrian) at surface, covers < 0.1 % of this area

North of Troy: shale, limestone; Hatch Hill Formation-shale, dolostone; West Castleton Formation-shale, limestone, conglomerate.

Undifferentiated Medina Group and Queenston Formation (Upper Ordovician - Lower Silurian) at surface, covers < 0.1 % of this area

Grimsby Formation-sandstones, shale; and Queenston Formation-siltstone, shale.

Hortonville Formation - shale and phyllite (Upper Ordovician) at surface, covers < 0.1 % of this area

Dark-gray siliceous shale and phyllite containing thin beds of bluish-gray argillaceous limestone and minor beds of gray to tan quartzite. Grades into limy shales of the Stony Point Formation. Unit mapped west of the Taconic allochthon, and northwest of the Sudbury slice. Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

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

Commonly biotitic; garnetiferous, pyroxenic, in and adjacent to central massif of Adirondacks.

Copake and Halcyon Lake Formations, Rochdale Limestone (Lower Ordovician) at surface, covers < 0.1 % of this area

Columbia County: Copake Formation-limestone, dolostone; Halcyon Lake Formation-chert, calc-dolostone.

Beekmantown Group (in part) (Cambrian) at surface, covers < 0.1 % 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.

Akron Dolostone (Upper Silurian) at surface, covers < 0.1 % of this area

Bertie Formation - dolostone, shale.

Nassau Formation of Potter (1972) - Rensselaer Graywacke member (Lower Cambrian and Neoproterozoic) at surface, covers < 0.1 % of this area

Nassau Formation of Potter (1972) - Rensselaer Graywacke member. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

West Hill and Gardeau Formations (Upper Devonian) at surface, covers < 0.1 % of this area

Shale, siltstone; Roricks Glen Shale; upper Beers Hill Shale; Grimes Siltstone.

Quassaic Quartzite (Upper Ordovician) at surface, covers < 0.1 % of this area

Quartzite, sandstone, conglomerate.

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

Potsdam Sandstone

Onondaga Limestone (Middle Devonian) at surface, covers < 0.1 % of this area

Seneca, Morehouse (cherty), and Nedrow Limestone Members, Edgecliff cherty Limestone Member, local bioherms.

Mount Merino Formation (Upper Ordovician) at surface, covers < 0.1 % of this area

Light-gray, powdery-weathering, and red, green, and dark-gray, thinly bedded siliceous argillite and mudstone distinguished from the Indian River Slate by abundance of cherty siliceous layers. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

Interlayered amphibolite and hornblende granitic gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Interlayered amphibolite and hornblende granitic gneiss.

Taconic Melange (Middle Ordovician) at surface, covers < 0.1 % of this area

Chaotic mixture of Early Cambrian thru Middle Ordovician pebble to block-size angular to rounded clasts in a pelitic matrix of Middle Ordovician (Barneveld) age. Rims and floors earlier submarine gravity slides of Taconian Orogeny.

Brunswick Formation (Upper Triassic) at surface, covers < 0.1 % of this area

Mudstone, sandstone and arkose.

Undifferentiated Lower Devonian and Silurian rocks (Lower Devonian - Silurian) at surface, covers < 0.1 % of this area

In northern Ulster County: Port Ewen thru Manlius Limestones; Rondout Dolostone; Binnewater Sandstone; High Falls Shale. In Orange County: Kanhouse Sandstone; Woodbury Creek Formation-shale, sandstone; Esopus Shale; Connelly Conglomerate; Central Valley Sandstone; New Scotland Limestone thru Rondout Dolostone; Decker Limestone; Poxono Island Formation-shale, dolostone; Longwood Shale; Green Pond Conglomerate.

Nassau Formation (Cambrian?) at surface, covers < 0.1 % of this area

Shale, quartzite.

Enfield"" and Kattel Formations (Upper Devonian) at surface, covers < 0.1 % of this area

Shale, siltstone, sandstone.

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

Shale, sandstone.

Hornblende syenite gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Overprint signifies inequigranular texture.

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

Sandstone, shale.

Pyroxene-hornblende-quartz-plagioclase gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Pyroxene-hornblende-quartz-plagioclase gneiss.

Leucogranitic gneiss (Middle Proterozoic) at surface, covers < 0.1 % 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.

Austin Glen Graywacke (Upper Ordovician) at surface, covers < 0.1 % of this area

Unit is indistinguishable from beds in the Austin Glen Graywacke (after Potter, 1972) (Oag) interpreted as synorogenic autochthonous rocks. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

Hammer Creek Formation (Upper Triassic) at surface, covers < 0.1 % of this area

Conglomerate.

Mettawee Slate (Cambrian?) at surface, covers < 0.1 % of this area

North of 43 degrees includes Castleton (North Brittain) Conglomerate. Mudd Pond Quartzite, Zion Hill Quartzite, and Bomoseen Graywacke Members.

Palisade Diabase (Early Jurassic) at surface, covers < 0.1 % of this area

Palisade Diabase

Mount Merino and Indian River Formations (Ordovician) at surface, covers < 0.1 % of this area

Shale, argillite, chert.

New Milford Formation (Upper Devonian) at surface, covers < 0.1 % of this area

Sandstone, shale.

Stuyvesant Falls Formation (Ordovician) at surface, covers < 0.1 % of this area

Shale, siltstone.

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

Mangerite or charnockite, and the Yach lithology.

Hatch Hill Formation (Upper Cambrian) at surface, covers < 0.1 % of this area

Dark-gray to black, sooty- to rusty-weathering, splintery-fractured pyritic slate and phyllite and interbedded bluish-gray dolomitic quartzite. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

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

Shale, siltstone; Rushford Sandstone; Caneadea, Canisteo, and Hume Shales; Canaseraga Sandstone; South Wales and Dunkirk Shales; In Pennsylvania: Towanda Formation-shale, sandstone.

Garnet-biotite-quartz-feldspar gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Quartzite, quartz-feldspar gneiss, calcsilicate rock.

Bedford Gneiss (Ordovician?) at surface, covers < 0.1 % of this area

Biotite-quartz-plagioclase gneiss and interlayered amphibolite; in part with augen of andesine and microcline.

Serpentinite (Lower Ordovician) at surface, covers < 0.1 % of this area

Serpentinite.

Everett Schist (Cambrian?) at surface, covers < 0.1 % of this area

Minor meta-graywacke lenses. Includes Greylock Schist in Massachusetts.

Rusty and gray biotite-quartz-feldspar gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Rusty facies contains variable amounts of garnet, sillimanite, cordierite, graphite, sulfides; minor marble and calcsilicate rock.

Stockbridge Formation (Cambrian - Lower Ordovician) at surface, covers < 0.1 % of this area

Calcitic and dolomitic marble.

Poughquag Quartzite (Cambrian) at surface, covers < 0.1 % of this area

(includes local Dalton Formation at base)-locally conglomeratic.

Briarcliff Dolostone and Pine Plains Formation (Cambrian) at surface, covers < 0.1 % of this area

Briarcliff - locally cherty; Pines Plains - dolostone, shale, oolite.

Rondout Formation (Upper Silurian) at surface, covers < 0.1 % of this area

Dolostone, limestone; Binnewater Sandstone; High Falls Shale; Warwarsing Limestone; Decker Limestone; Bossardville Limestone; Poxono Island Formation-shale, dolostone.

Lower Beers Hill Shale (Upper Devonian) at surface, covers < 0.1 % of this area

Dunn Hill, Millport, and Moreland Shales.

Cumberland Head Argillite (Middle Ordovician) at surface, covers < 0.1 % of this area

Cumberland Head Argillite

Briarcliff Dolostone and Pine Plains Formation (Cambrian) at surface, covers < 0.1 % of this area

Columbia County: Pine Plains-dolostone, oolite, shale.

Poultney Formation (""B"" and ""C"" Members) (Ordovician) at surface, covers < 0.1 % of this area

North of Troy; shale, slate, siltstone.

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.

Harrison/Ravenswood Gneiss (Ordovician?) at surface, covers < 0.1 % of this area

Harrison Gneiss - in New York and Connecticut, Brookfield diorite gneiss in Connecticut, and Ravenswood Gneiss in Brooklyn - biotite-hornblende-quartz-plagioclase gneiss with accessory garnet and sphene; plagioclase commonly occurs as augen.

Copake and Rochdale Formations (Lower Ordovician) at surface, covers < 0.1 % of this area

Copake Formation-limestone, dolostone, siltstone; Rochdale Formation-limestone, dolostone; Halcyon Lake Dolostone-locally cherty.

Germantown Formation (Cambrian) at surface, covers < 0.1 % of this area

Shale, limestone, conglomerate.

Stissing Formation (Cambrian) at surface, covers < 0.1 % of this area

Dolostone, shale.

Metanorthosite and anorthositic gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Metanorthosite and anorthositic gneiss.

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

Sandstone, arenaceous limestone.

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

Ferrohedenbergite-fayalite granite and granite gneiss.

Ilion Shale (Upper Silurian) at surface, covers < 0.1 % of this area

Ilion Shale

Interlayered metasedimentary rock and granitic gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Interlayered metasedimentary rock and granitic gneiss.

Taconic Melange (Middle Ordovician) at surface, covers < 0.1 % of this area

Chaotic mixture of Early Cambrian thru Middle Ordovician pebble to block-size clasts in a pelitic matrix of Middle Ordovician (Barneveld) age. Rims and floors earlier submarine gravity slides of Taconian Orogeny.

Calcitic and dolomitic marble (Middle Proterozoic) at surface, covers < 0.1 % of this area

Variably siliceous; in part with calcsilicate rock and amphibolite.

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

Limestone, chert.

Indian River Slate (Upper Ordovician) at surface, covers < 0.1 % of this area

Deep-maroon and bluish-green-weathering, well-bedded and variegated slate; contains minor centimeter-thick, white-weathering, red and bluish-black cherty layers characteristic of the Mount Merino Formation. Contains graptolites of the C. bicornis Biozone (Berry, 1961). Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

Brunswick Formation (Upper Triassic) at surface, covers < 0.1 % of this area

Sandstone, siltstone and mudstone.

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

Leucogranitic gneiss

Port Ewen thru Manlius Limestone, Rondout Dolostone, undifferentiated. (Upper Silurian - Lower Devonian) at surface, covers < 0.1 % of this area

Port Ewen thru Manlius Limestone, Rondout Dolostone, undifferentiated.

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.

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

Biotite and/or hornblende-quartz-feldspar gneiss.

Fort Ann Formation (Lower Ordovician) at surface, covers < 0.1 % of this area

(Shown only in New York State). Medium- to dark-gray and mottled, medium- to thick-bedded dolomitic limestone and buff-weathering dolostone. Part of the Beekmantown Group. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts).

Interlayered amphibolite and granitic, charnockitic, mangeritic, or syenitic gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

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

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

Metagabbro, olivine metagabbro, derived amphibolite.

Chipman Formation - Bascom Formation (Middle and Lower Ordovician) at surface, covers < 0.1 % of this area

Interbedded orangey-tan- to buff-weathering dolostone and bluish-gray to gray mottled dolomitic limestone or calcite marble and calcareous sandstone. In southern Vermont east of the Taconic Range, rocks mapped as Bascom Formation may include unmapped members of the Chipman Formation. Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

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

Grimsby Formation-sandstone, shale.

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

Alsen, Becraft, New Scotland, Kalkberg, Coeymans, and Manlius Limestones.

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

Shale, sandstone, conglomerate.

Glens Falls Limestone (Upper Ordovician) at surface, covers < 0.1 % of this area

Dark-bluish-gray-weathering, thinly bedded dark-gray to black granular limestone; locally grades upward into sooty- weathering shaly limestone beds rich in fragments of the trilobite Cryptolithus. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts). Also part of the Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

Balmville Limestone (Middle Ordovician) at surface, covers < 0.1 % of this area

Vermont: Whipple Limestone.

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

Stony Point Shale

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

Limestone, chert; Port Jervis Formation (near Port Jervis only)-shale, limestone, chert.

Browns Pond Formation of Rowley and others (1979) (Lower Cambrian) at surface, covers < 0.1 % of this area

Gray to black slate, punky-weathering calcitic wacke and mudstone, and thin limestone breccia in part equivalent to the West Castleton Formation. Shown only in the Granville, N.Y., area. Locally purple and green slate above black slate of the Browns Pond is interpreted as a lens of the Mettawee slate facies in the Bull Formation. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

Balmville Limestone (Middle Ordovician) at surface, covers < 0.1 % of this area

Balmville Limestone

Hornblende norite (Upper Ordovician) at surface, covers < 0.1 % of this area

Hornblende is poikilitic.

Fordham Gneiss (B member) (Precambrian - Middle Proterozoic) at surface, covers < 0.1 % of this area

fb: amphibolite, biotite and/or hornblende-garnet- quartz-plagioclase gneiss.

Pawlet Formation (Upper Ordovician) at surface, covers < 0.1 % of this area

Light-gray, tan-weathering, mica-speckled, massive to thin-bedded quartz-plagioclase wacke interbedded with dark-gray carbonaceous slate. Contains distinctive autoclastic chips of gray slate, fragments of dacitic to andesitic volcanics, and subangular clasts of dark-gray quartz and oligoclase. Interbedded black slates contain graptolites of the C. bicornis Biozone (see Webby and others, 2004, fig. 2.1) (lower to middle Mohawkian). Interpreted as uncomformable on rocks as old as the Hatch Hill Formation and possibly the West Castleton Formation of the allochthon. Unit is indistinguishable from beds in the Austin Glen Graywacke (after Potter, 1972) (Oag) interpreted as synorogenic autochthonous rocks. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

Cambrian thru Middle Ordovician carbonate rock (Cambrian - Middle Ordovician) at surface, covers < 0.1 % of this area

Occuring as slivers caught along thrusts of later allochthones, or carbonate blocks in Taconic Melange. Also mapped as horses along normal faults.

Fort Cassin Formation (Middle and Lower Ordovician) at surface, covers < 0.1 % of this area

Shown locally from Whitehall, N.Y., to Orwell, Vt. Laterally equivalent to Providence Island Dolostone. Part of the Beekmantown Group. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts).

Biotite augite norite (Upper Ordovician) at surface, covers < 0.1 % of this area

Biotite augite norite

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).

Pyroxenite (Upper Ordovician) at surface, covers < 0.1 % of this area

Pyroxenite

Manhattan Formation (A Member) (Middle Ordovician) at surface, covers < 0.1 % of this area

Sillimanite-garnet-muscovite-biotite-quartz- plagioclase schists; calcite marble and calcsilicate rock at base.

Fordham Gneiss (E member) (Precambrian - Middle Proterozoic) at surface, covers < 0.1 % of this area

fe: garnet-biotite-quartz-plagioclase gneiss, and amphibolite.

Fort Cassin Formation - Sciota Limestone Member (Middle and Lower Ordovician) at surface, covers < 0.1 % of this area

Light-gray, fine- grained, and dark-gray, fossiliferous, and platy bluish-gray limestone. Contains upper Ibexian to lower Whiterockian conodonts at the type locality near Sciota School House, in the Benson quadrangle (J.E. Repetski, USGS, written commun., 2004). Part of the Beekmantown Group. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts).

Whitehall Formation - dolostone (Lower Ordovician and Upper Cambrian) at surface, covers < 0.1 % of this area

Predominantly light-gray and pinkish-gray, coarse-grained dolostone and cherty dolostone. Part of the Beekmantown Group. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts).

Providence Island Dolostone (Middle and Lower Ordovician) at surface, covers < 0.1 % of this area

Light-buff-tan- weathering, massive to thick-bedded, fine-grained dark-gray dolostone; has “beeswax-scored” surfaces; contains thin layers of fossiliferous bluish-gray limestone (largely equivalent to the Bridport Member of the Chipman Formation, north of Orwell). Part of the Beekmantown Group. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts).

Stockton Formation (Upper Triassic) at surface, covers < 0.1 % of this area

Arkose, conglomerate, and mudstone.

Oswego Sandstone (Upper Ordovician) at surface, covers < 0.1 % of this area

Oswego Sandstone

Winooski Dolostone (Middle Cambrian) at surface, covers < 0.1 % of this area

Well-bedded dolostone weathering beige, cream, and buff, with green, red, or gray phyllite, siliceous partings, and thin beds of blue-quartz-pebble conglomerate and quartzite. Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

Olivine pyroxenite (Upper Ordovician) at surface, covers < 0.1 % of this area

In part with poikilitic hornblende; local peridotite.

Diorite with hornblende and/or biotite (Upper Ordovician) at surface, covers < 0.1 % of this area

Diorite with hornblende and/or biotite.

Oriskany Sandstone (Lower Devonian) at surface, covers < 0.1 % of this area

Oriskany Sandstone.

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

Light-gray, tan, and dark-gray, well- bedded pebbly quartzite, crossbedded vitreous quartzite, and local conglomerate. Part of the Beekmantown Group. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts).

Unadilla Formation (Middle - Late Devonian) at surface, covers < 0.1 % of this area

Shale, siltstone.

Whipstock Breccia in the Walloomsac Formation (Upper Ordovician) at surface, covers < 0.1 % of this area

Largely a tectonic breccia formed in situ; contains abundant pseudo-pebbles. Part of the Taconic Allochthon. Wildflysch-like conglomerates within the Hortonville, Ira, and Walloomsac Formations occur as local areas of black slate rich in inclusions of quartzite, greenish-gray slate, wacke, and punky-weathering bluish-gray limestone, interpreted as sedimentary breccias, deposited in front of the advancing Taconic allochthon (Upper Ordovician) (Zen, 1961; Potter, 1972; Fisher, 1985). Exposed near the western and northern margin of the allochthon and in the Bennington area at the type Whipstock. Here and at many localities the Forbes Hill and Whipstock breccias are tectonic breccias formed in situ by disruption of thin to thick beds, laminae, and carbonate-quartz-sulfide veins rather than clastic sedimentary rocks. The cleavage and related folding commonly is a late strain-slip cleavage characterized by a strong down-plunge lineation parallel to reclined hingelines of minor folds of foliation and compositional layering. Units are retained although interpretation as sedimentary wildflysch deposits is in part questionable.

Calcitic and dolomitic marble (Middle Proterozoic) at surface, covers < 0.1 % of this area

Variably siliceous; in part with calcsilicate rock and amphibolite.

Middlebury Limestone (Middle Ordovician) at surface, covers < 0.1 % of this area

Buff-streaked, dark-bluish-gray, thinly bedded and well-foliated dolomitic limestone, shown above the Champlain thrust south of Middlebury. Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

Muscovite-biotite granodiorite (Upper Devonian) at surface, covers < 0.1 % of this area

Muscovite-biotite granodiorite - of Peekskill Pluton.

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

Biotite and/or hornblende-quartz-feldspar gneiss, similar to Yonkers Gneiss and parts of Fordham C member.

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

Biotite-hornblende granite and granite gneiss.

Black River Group (Middle Ordovician) at surface, covers < 0.1 % of this area

Chaumont Limestone-chert; Lowville Limestone; Pamelia Dolostone.

Connoquenessing and Sharon Formations (Lower Pennsylvanian) at surface, covers < 0.1 % of this area

Sandstone, shale; Sharon Formation-shale, sandstone, conglomerate; Olean Conglomerate 50-100 ft. (15-30 m).

Fordham Gneiss (A member) (Precambrian - Middle Proterozoic) at surface, covers < 0.1 % of this area

fa: garnet-biotite-quartz-plagioclase gneiss, amphibolite, biotite-hornblende-quartz-plagioclase gneiss, quartz-feldspar granulite.

Biotite-quartz-plagioclase gneiss (Middle to Early Mesoproterozoic) at surface, covers < 0.1 % of this area

Light-greenish-gray to pinkish-gray, well-foliated and well-layered quartz-rich gneiss and more mafic biotite-hornblende-pyroxene-quartz-plagioclase gneiss irregularly distributed within unit. Unit may be in part older than the tonalitic gneiss (Y2bt). Paragneiss. Rocks of the Adirondacks in Vermont and in the Whitehall, N.Y., area.

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.

Great Meadows Formation - Winchell Creek Member (Lower Ordovician) at surface, covers < 0.1 % of this area

Tan-weathering, gray, well-bedded and crossbedded laminated quartzite and dolostone; sandy beds weather to a woody-grained surface texture. Part of the Beekmantown Group. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts).

Great Meadows Formation - dolostone (Lower Ordovician) at surface, covers < 0.1 % of this area

Light-gray, medium-grained, medium- to thick-bedded dolostone, locally cherty. Part of the Beekmantown Group. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts).

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

Includes Hortonville and Ira Shales in Vermont.

Greenstones and tuffs and/or basalt (Cambrian?) at surface, covers < 0.1 % of this area

Greenstones and tuffs and/or basalt

Fort Cassin Formation - Ward Siltstone Member (Lower Ordovician) at surface, covers < 0.1 % of this area

Light-tan to gray, thinly bedded and crossbedded, calcareous and dolomitic siltstone and quartzite in beds similar to the quartzite of the Root Pond Quartzite Member (Ofcrp). Part of the Beekmantown Group. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts).

Gabbro or norite to hornblende diorite (Upper Ordovician) at surface, covers < 0.1 % of this area

Rock complex with minor pyroxenite; Croton Falls and Peach Lake complexes in New York, and Mt. Prospect Complex in Connecticut.

Lower Walton Formation (Upper Devonian) at surface, covers < 0.1 % of this area

Shale, sandstone, conglomerate.

Carbonaceous phyllite and siltstone (Lower Cambrian and Neoproterozoic) at surface, covers < 0.1 % of this area

Medium- to dark-gray carbonaceous phyllite, gray slate, and metasiltstone, locally containing light-gray, medium- to thick-bedded quartzite and dolomitic quartzite (CZbq). Unit resembles rocks of the Netop Formation but lacks the distinctive lenses and pods of bluish-gray dolostone of the Netop on Dorset Mountain, although lenses of whitish quartzite are present. Rocks of the Dorset Mountain slice (includes Dorset Mountain proper and Mount Equinox, southward to West Mountain near Bennington). Part of the Taconic Allochthon.

Hague Gneiss of Alling (1918) (Middle Mesoproterozoic) at surface, covers < 0.1 % of this area

Yellowish-grayish- green to rusty-sulfidic-weathering, garnet (large)-sillimanite-biotite-orthoclase-plagioclase-quartz schist or gneiss, locally containing mappable and discontinuous lenses, layers or pods of quartzite, marble, or calc-silicate rock. Contains a coarse sillimanite-feldspar gneissosity older than the regional Ottawan foliation. Paragneiss. Rocks of the Adirondacks in Vermont and in the Whitehall, N.Y., area.

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

Grayish-red sandstone, siltstone, shale, and mudstone; units of gray sandstone occur in upper part; lithologies in upper part arranged in fining-upward cycles. In the Altoona area, the Catskill Formation is mapped as the Duncannon, Sherman Creek, and Irish Valley Members, which are described under "Central and Eastern Pennsylvania" provinces.

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.

Muscovite-biotite granite (Upper Devonian) at surface, covers < 0.1 % of this area

Muscovite-biotite granite - of Peekskill Pluton.

West Castleton Formation - quartzite (Middle and Lower Cambrian) at surface, covers < 0.1 % of this area

Boudins of whitish-gray-weathering, bluish-gray quartzite. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

Hortonville Formation - limestone (Upper Ordovician) at surface, covers < 0.1 % of this area

Near base contains bluish-gray, granular, smooth-weathering fossiliferous limestone. Unit mapped west of the Taconic allochthon, and northwest of the Sudbury slice. Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

Beers Hill, Dunn Hill, Millport, and Moreland Shales (Upper Devonian) at surface, covers < 0.1 % of this area

Beers Hill, Dunn Hill, Millport, and Moreland Shales.

Cambrian thru Middle Ordovician carbonate rock (Cambrian - Middle Ordovician) at surface, covers < 0.1 % of this area

Occuring as slivers caught along thrusts of later allochthones, or carbonate blocks in Taconic Melange. Also mapped as horses along normal faults.

Ladentown diabase and baslatic lava (Upper Triassic) at surface, covers < 0.1 % of this area

Ladentown diabase and basaltic lava

Conneaut Group, undivided (Upper Devonian) at surface, covers < 0.1 % of this area

Germania Formation-shale, sandstone; Whitesville Formation-shale, sandstone; Hinsdale Sandstone; Wellsville Formation-shale, sandstone; Cuba Sandstone.

Long Run and Walcksville Members of Catskill Formation, undivided (Devonian) at surface, covers < 0.1 % of this area

Includes, in descending order, the Long Run (Dclr) and Walcksville (Dcw) Members of the Catskill Formation, which are described separately below.

Lamprophyre, trachyte, and rhyolite dikes (Jurassic - Lower Cretaceous) at surface, covers < 0.1 % of this area

Lamprophyre, trachyte, and rhyolite dikes - not shown in Proterozoic terrane.

Whitehall Formation - limestone (Lower Ordovician and Upper Cambrian) at surface, covers < 0.1 % of this area

Layers of gray limestone. Part of the Beekmantown Group. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts).

Chipman Formation - Bridport Member (Middle Ordovician) at surface, covers < 0.1 % of this area

Thickly bedded, “beeswax-scored,” orangey-beige-weathering, yellowish-gray to light-bluish-gray dolostone, dark-gray fine-grained to aphanitic dolostone, and minor beds of bluish-gray limestone. Transitions eastward into the Beldens Member with addition of limestone beds. Equivalent to Providence Island Dolostone (Ofcpi). Chipman Formation (mapped south of Wings Point). Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

Ticonderoga Formation (Upper Cambrian) at surface, covers < 0.1 % of this area

Light-gray, yellowish-gray- to buff- weathering quartzose dolostone, pebbly dolomitic quartzite, and interbedded quartzite. Part of the Beekmantown Group. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts).

Granodioritic augen gneiss and quartz monzonite gneiss (Late Mesoproterozoic) at surface, covers < 0.1 % of this area

Light-gray to pinkish-gray, garnet-biotite-plagioclase-micro-perthite augen granodioritic gneiss, locally massive but well foliated. Contains deformed phenocrysts (augen) aligned in old relict flow (?) foliation. Rocks of the Adirondacks in Vermont and in the Whitehall, N.Y., area.

Ira Formation - limestone (Upper Ordovician) at surface, covers < 0.1 % of this area

Contains basal limestone, locally referred to as the Whipple Marble Member. Unit mapped along east side of the Taconic allochthon south to Bennington. Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

Walloomsac Formation - limestone (Upper Ordovician) at surface, covers < 0.1 % of this area

Basal limestone member. Tectonically shredded, silty varieties near and on Whipstock Hill constitute the Whipstock Breccia Member of Potter (1972) (Oww). Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

Plattekill and Ashokan Formations (Middle Devonian) at surface, covers < 0.1 % of this area

Shale, sandstone; Ashokan Formation-shale, sandstone.

Netop Formation - wacke member (Cambrian and Neoproterozoic) at surface, covers < 0.1 % of this area

Bluish-gray, fine-grained metawacke and metasiltstone, perhaps equivalent to the Bomoseen Graywacke Member of the Bull Formation. Rocks of the Dorset Mountain slice (includes Dorset Mountain proper and Mount Equinox, southward to West Mountain near Bennington). Part of the Taconic Allochthon.

Fort Cassin Formation - Root Pond Quartzite Member (Middle and Lower Ordovician) at surface, covers < 0.1 % of this area

Light-gray to tannish-white, well-bedded and vitreous steel-gray quartzite interbedded with orangey-tan- and beige-weathering dolostone and thin beds of fossiliferous limestone. Named for occurrences near Root Pond in the Benson quadrangle, but herein extended to include thin lenses of quartzite that occur interbedded at several positions in the Fort Cassin Formation. Interbedded limestones contain upper Ibexian conodonts southwest of Root Pond (J.E. Repetski, USGS, written commun., 2004). Part of the Beekmantown Group. Rocks of the Laurentian Margin. Part of the Adirondack lowlands and Lake Champlain lowlands (west of the Orwell and Champlain thrusts).

Trachyte porphyry (Jurassic - Lower Cretaceous) at surface, covers < 0.1 % of this area

Laccolith (?) at Cannon's Point near Willsboro, Essex County.

Sillimanite-cordierite-almandine-biotite-quartz-feldspar gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Sillimanite-cordierite-almandine-biotite-quartz-feldspar gneiss.

Towamensing Member of Catskill Formation (Devonian) at surface, covers < 0.1 % of this area

Dominantly gray sandstone and some siltstone and shale; freshwater fossils.

Bull Formation - Zion Hill Quartzite member (Lower Cambrian and Neoproterozoic) at surface, covers < 0.1 % of this area

Light-greenish-gray to whitish-gray-weathering, massive vitreous quartzite; locally contains quartz-pebble conglomerate and wacke near the base. Unit commonly 5 to 10 m thick but is as much as 65 m thick; occurs as many lenticular quartzites within the Mettawee slate facies in the Bull Formation, not restricted to one horizon. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

Quartzite (Middle Mesoproterozoic) at surface, covers < 0.1 % of this area

Light-tan to yellowish-gray, massive to well-layered magnetite-garnet quartzite and magnetite-biotite-garnet quartzite in beds as much as 10 m thick. Occurs in two layers, one within or attached to the Hague Gneiss and one within biotite-quartz-plagioclase gneiss (Y2bpg) beneath the Hague Gneiss. The latter is rich in microcline and passes through interbedding into a quartzose facies of Y2bpg. Paragneiss. Rocks of the Adirondacks in Vermont and in the Whitehall, N.Y., area.

Pharaoh Mountain Gneiss of Wiener and others (1984) (Late to Middle Mesoproterozoic) at surface, covers < 0.1 % of this area

Rusty-grayish-brown- to brown-weathering, knubbly coarse-grained magnetite-garnet-hornblende and pyroxene-bearing charnockitic gneiss and garnet-hornblende granite gneiss. Has large polycrystalline aggregates of plagioclase as much as 1.5 cm long, recrystallized from pre-Ottawan phenocrysts (?) of plagioclase. Contains mappable and folded screens of marble, calc-silicate rock (Y2cs), mafic diopside-hypersthene gneiss, and interbedded sillimanite-garnet quartzite (Y2qz). Interpreted as largely intrusive but may contain some charnockitic gneiss of uncertain origin. Rocks of the Adirondacks in Vermont and in the Whitehall, N.Y., area.

Carbonate - limestone (Cambrian and Neoproterozoic?) at surface, covers < 0.1 % of this area

Pods, lenses, or zones of thinly bedded limestone (ls), dolostone (d), and limestone conglomerate in the Mettawee slate facies in the Bull Formation, West Castleton Formation, and Hatch Hill Formation. These rocks locally contain Lower Cambrian fossils, but may range in age from Neoproterozoic to Late Cambrian. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

Chazy, Black River, and Trenton Limestones - undifferentiated (Upper and Middle Ordovician) at surface, covers < 0.1 % of this area

See individual formation descriptions. Shown locally west of the Taconic allochthon. Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

Eagle Bridge Quartzite (Lower Cambrian) at surface, covers < 0.1 % of this area

Dull-gray, pitted, and bluish-gray dolomitic quartz wacke and quartzite distinguished by small pebbles and grains of dark-blue to black quartz, dacitic rock fragments, and abundant plagioclase. Beds resembling the Eagle Bridge Quartzite may occur at several stratigraphic positions within the black slate and gray phyllite of the West Castleton and Hatch Hill(?) Formations, undifferentiated (Cwcu), and near the base of the Poultney Formation, and probably are not all correlative. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

High Point Member (Upper Ordovician) at surface, covers < 0.1 % of this area

(Drake, 1991) - Medium-dark-gray, thin-bedded shale, siltstone and fine-grained sandstone, containing turbidite sequences Tbcde to Tcde of Bouma (1962). Interbedded with less abundant, light-yellowish-gray-weathering, medium-gray to medium-dark-gray, medium-grained, medium- to thick-bedded and massive, quartz- and calcareous-cemented quartz sandstone containing rip-ups of medium- to dark-gray shale and siltstone that commonly consist of Bouma (1962) turbidite sequences Tab to Ta. Restricted to northeast section of Martinsburg outcrop belt. Thermally metamorphosed near intrusive bodies. Grades along strike to the southwest into Ramseyburg Member by decrease in average grain size, absence of shale rip-ups, and lack of siliceous cement. Lower contact gradational and placed at base of lowermost thick-bedded graywacke or amalgamated graywacke containing shale rip-ups. Unit assigned to Orthograptus ruedemanni zone to Climacograptus spiniferus zone of Riva (1969, 1974) using graptolites collected by Parris and Cruikshank (1992). Thickness ranges from 0 to 1,370 m (0-4,500 ft).

Biotite tonalite gneiss (Middle Mesoproterozoic) at surface, covers < 0.1 % of this area

Predominantly chalky-white-weathering, massive biotite tonalite gneiss. Passes laterally into white, fine-grained trondhjemitic aplite near contacts with larger screens of paragneiss. U-Pb zircon Thermal Ionization Mass Spectrometry (TIMS) age of 1329±37 Ma (McLelland and Chiarenzelli, 1990) obtained from exposure 1.5 km west of Austin Hill on the west side of South Bay, west of Whitehall, N.Y. Contains lenses and screens of rusty sulfidic garnet-biotite-feldspar-quartz schist, dark-gray garnet-feldspar quartzite, and calc-silicate gneiss on south end of Austin Hill. Unit interpreted as intrusive into some paragneiss units that are here older than 1328±32 Ma (McLelland and Chiarenzelli, 1990). Rocks of the Adirondacks in Vermont and in the Whitehall, N.Y., area.

Marble and calc-silicate gneiss (Middle Mesoproterozoic) at surface, covers < 0.1 % of this area

Medium-dark-gray to light-gray diopside-phlogopite-scapolite-calcite marble, phlogopite-tremolite-talc schist, and dark-gray diopside-hornblende (actinolite)-plagioclase calc-silicate gneiss. Paragneiss. Rocks of the Adirondacks in Vermont and in the Whitehall, N.Y., area.

Cheshire Quartzite and Dalton Formation (Cambrian) at surface, covers < 0.1 % of this area

Cheshire Quartzite and Dalton Formation

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

Greenish-gray, olive, and buff sandstone and siltstone, and gray shale in varying proportions; includes "Pocono" ("Knapp") and Oswayo of earlier workers; difficult lithologic distinction between Oswayo and "Knapp"- "Pocono" south and east of type area at Olean, N. Y.; contains marine fossils; includes lateral equivalents of Shenango Formation, Cuyahoga Group, Corry Sandstone, Bedford Shale, and Cussewago Sandstone, plus Oswayo Formation.

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.

Ramseyburg Member (Upper and Middle Ordovician) at surface, covers < 0.1 % of this area

(Drake and Epstein, 1967) - Interbedded medium- to dark-gray, to brownish-gray, fine- to medium-grained, thin- to thick-bedded graywacke sandstone and siltstone and medium- to dark-gray, laminated to thin-bedded shale and slate. Unit may form complete turbidite sequences, Tabcde (Bouma, 1962), but basal cutout sequences Tcde dominate. Basal scour, sole marks, and soft-sediment distortion of beds are common in graywacke. Thermally metamorphosed near intrusive bodies. Lower contact placed at bottom of lowest thick- to very thick bedded graywacke, but contact locally grades through sequence of dominantly thin-bedded shale and slate and minor thin- to medium-bedded discontinuous and lenticular graywacke beds in the Bushkill member. Parris and Cruikshank (1992) correlate unit with Orthograptus ruedemanni to lowest part of Climacograptus spiniferus zones of Riva (1969, 1974). Thickness ranges from 640 m (2,100 ft) in Delaware River Valley, to 1,524 m (5,000 ft) near Stillwater, to 1067 m (3,500 ft) at New York State line.

Allentown Dolomite (Lower Ordovician and Upper Cambrian) at surface, covers < 0.1 % of this area

(Wherry, 1909) - Very thin to very thick bedded dolomite containing minor orthoquartzite and shale. Upper part is medium-light- to medium-dark-gray, fine- to medium-grained, locally coarse-grained, medium- to very thick bedded dolomite. Floating quartz sand grains and two sequences of medium-light- to very light gray, thin-bedded quartzite and discontinuous, dark-gray chert lenses occur directly below upper contact. Rhythmically bedded lower dolomite beds alternate between light and dark gray weathering, medium and very light gray, fine and medium grained, and thin and medium bedded, which are interbedded with shaly dolomite. Ripple marks, crossbeds, edgewise conglomerate, mud cracks, oolites, and algal stromatolites occur throughout unit, but more typically in lower part. Shaly dolomite increases downward toward lower conformable contact with the Leithsville Formation. Oldest beds contain trilobite fauna of early Late Cambrian age; younger beds contain latest Cambrian fauna (Howell, 1945; Howell and others, 1950). Thickness about 580 m (1,900 ft).

Graptoliferous slate (Upper Ordovician) at surface, covers < 0.1 % of this area

Black slate of Climacograptus bicornis Biozone on and west of Whipstock Hill, otherwise typical of slates of the Walloomsac Formation shown as Ow. Part of the Taconic Allochthon.

Bull Formation - Mud Pond Quartzite member (Lower Cambrian) at surface, covers < 0.1 % of this area

Buff- to gray-weathering vitreous quartzite as much as 6 m thick, containing deeply weathered ovoidal areas of carbonate-cemented quartzite. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

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

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

Nassau Formation of Potter (1972) - basaltic volcanics (Lower Cambrian and Neoproterozoic) at surface, covers < 0.1 % of this area

Includes basaltic volcanics. Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

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.

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

White- to light-gray-weathering, white, grayish-white, or, less commonly pinkish-orange, coarse- to locally fine-crystalline calcite marble with accessory amounts of graphite, phlogopite, chondrodite, clinopyroxene, and serpentine. Contains pods and layers of clinopyroxene-garnet skarn, hornblende skarn, and clinopyroxene-rich rock. Thin layers of metaquartzite occur locally. Intruded by the Mount Eve Granite in the Pochuck Mountain area. Franklin Marble is host to the Franklin and Sterling Hill zinc ore bodies; exploited for talc and asbestiform minerals near Easton, Pennsylvania. Subdivided into an upper marble, "Wildcat marble," and a lower marble, "Franklin marble," by New Jersey Zinc Co. geologists (Hague and others, 1956).

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

Light-gray- to pinkish-white-weathering, tan to pinkish-white, fine- to medium-grained, well-layered gneiss composed principally of quartz, microcline, and lesser amounts of oligoclase. Common accessory minerals include biotite, garnet, magnetite, and, locally, sillimanite.

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.

Elizaville Formation (Cambrian - Ordovician) at surface, covers < 0.1 % of this area

Shale, argillite, quartzite.

Stockton Formation (Upper Triassic) at surface, covers < 0.1 % of this area

(Kmmel, 1897) - Light-gray, light-grayishbrown, yellowish- to pinkish-gray, or violet-gray to reddish-brown, medium- to coarse-grained arkosic sandstone and reddish- to purplish-brown mudstone, silty mudstone, argillaceous siltstone, and shale. Mudstone, siltstone and shale beds thicker and more numerous in central Newark basin west of Round Valley Reservoir. Sandstones mostly planar-bedded, with scoured bases containing pebble lags and mudstone rip-ups. Unit is coarser near Newark basin border fault, where poorly exposed, reddish-brown to pinkish-white, medium- to coarse-grained, feldspathic pebbly sandstone and conglomerate (Trss) and pebble to cobble quartzite conglomerate (Trscq). Maximum thickness of formation about 1,240 m (4,070 ft).

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

Gray, brown, and olive shale and siltstone; marine fossils. Includes the following members, in descending order: Tully-argillaceous limestone; Sherman Ridge, Montebello (sandstone), Fisher Ridge, Dalmatia, and Turkey Ridge. In south-central Pennsylvania, includes Clearville, Frame, Chaneysville, and Gander Run Members. Characterized by coarsening-upward cycles.

Bushkill Member (Middle Ordovician) at surface, covers < 0.1 % of this area

(Drake and Epstein, 1967) - Interbedded medium- to dark gray, thinly laminated to thick-bedded shale and slate and less abundant medium-gray to brownish-gray, laminated to thin-bedded siltstone. To the southwest, fine-grained, thin dolomite lenses occur near base. Complete turbidite sequences (Bouma, 1962) occur locally, but basal cutout sequences (Tbcde, Tcde or Tde) dominate. Conformable lower contact is placed at top of highest shaly limestone; elsewhere, lower contact is commonly strain slipped. Correlates with graptolite Climacograptus bicornis to Corynoides americanus zones of Riva (1969, 1974) (Parris and Cruikshank, 1992). Thickness ranges from 1,250 m (4,100 ft) in Delaware River Valley to 457 m (1,500 ft) at New York State line.

Pillow lava (Ordovician) at surface, covers < 0.1 % of this area

At Stark's Knob near Schuylerville, Saratoga County.

Walloomsac Formation - phyllite (Upper Ordovician) at surface, covers < 0.1 % of this area

A black carbonaceous highly graptoliferous phyllite. Tectonically shredded, silty varieties near and on Whipstock Hill constitute the Whipstock Breccia Member of Potter (1972) (Oww). Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

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

Olive-gray siltstone and shale, characterized by graded bedding; marine fossils; some very fine grained sandstone in northeast; black shale of Harrell Formation at base in Susquehanna Valley.

Shelburne Marble (Lower Ordovician) at surface, covers < 0.1 % of this area

Predominantly light-gray- to white- and bluish-gray-streaked calcite marble and massive white- and green-streaked calcite marble. Locally contains intermediate dolostone and gray limestone beds. Vermont Valley sequence and Middlebury synclinorium (above the Orwell and Champlain thrusts).

Sandy phyllite, granofels, and cherty phyllite (Upper Ordovician) at surface, covers < 0.1 % of this area

Gray and grayish-green rocks associated with Whipstock breccia on Whipstock Hill but of uncertain correlation. Part of the Taconic Allochthon.

Hornblendite (Upper Ordovician) at surface, covers < 0.1 % of this area

Hornblendite

Metagabbro (Late Mesoproterozoic) at surface, covers < 0.1 % of this area

Garnet-hornblende (±olivine) gabbro and dioritic gneiss; similar rock mapped in the Chittenden Intrusive Suite in Vermon. Rocks of the Adirondacks in Vermont and in the Whitehall, N.Y., area.

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

Pinkish-gray- to medium-buff-weathering, pinkish-white or light-pinkish-gray, medium- to coarse-grained, gneissoid to indistinctly foliated granite and sparse granite gneiss composed principally of microcline microperthite, quartz, oligoclase, and hornblende. Some phases are quartz syenite or quartz monzonite. Includes small bodies of pegmatite and amphibolite not shown on map. U-Pb age approximately 1,090 Ma (Drake and others, 1991b).

Shawangunk Formation (Middle and Lower Silurian) at surface, covers < 0.1 % of this area

(Mather, 1840; Epstein and Epstein, 1972) - Upper part is medium- to medium-dark-gray, or dark-greenish-gray, medium- to thick-bedded sandstone and pebble conglomerate having well rounded grains, some of which are limonite stained. Conglomerate consists of matrix-supported quartz and subordinate shale pebbles as long as 5 cm (2 in.) in poorly to well-sorted, planar tabular to trough crossbedded sandstone. Local black to dark-greenish-gray, thin-bedded shale near upper contact. Middle part, occurring in southwest and sporadically in northeast, is light- to medium-dark-gray, greenish-gray, interbedded thin- to medium-bedded, planar tabular to trough cross-bedded shale and sandstone. Grains are well rounded and moderately to well sorted. Contains sparse graphite flakes. Lower part is light- to medium-gray to light-olive-gray, thin- to thick-bedded quartz and feldspathic sandstone, quartzite, and quartz-pebble conglomerate, which is matrix-supported, poorly to well sorted, cross to planar bedded. Clasts are primarily quartz and sparse dark-gray argillite and black chert. Sandstone is feldspathic and locally approaches an arkose in compostion. Lower contact unconformable and, at places, is a fault of small displacement. Thickness approximately 427 m (1,400 ft).

Kimberlite and alnoite dikes and diatremes (Jurassic - Lower Cretaceous) at surface, covers < 0.1 % of this area

Kimberlite and alnoite dikes and diatremes.

Nassau Formation of Potter (1972) - Bomoseen Member (Neoproterozoic) at surface, covers < 0.1 % of this area

Pale-reddish-brown to light-gray-weathering, medium- and fine-grained, massive to thickly bedded, olive-green to gray micaceous quartz-feldspar graywacke and siltstone, locally containing coarse detrital muscovite, biotite, and autoclastic slate chips. Resembles finer grained parts of the Rensselaer Graywacke Member of the Nassau Formation (of Potter, 1972), and the Bird Mountain Grit (of Dale, 1900). Unit interfingers with and grades laterally into the Mettawee slate facies. In the Mt. Anthony area is shown as CZnb (Bomoseen Member of the Nassau Formation of Potter, 1972). Rocks of the Giddings Brook, Sunset Lake, and Bird Mountain slices. Part of the Taconic Allochthon.

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

White- to tan-weathering, greenish-gray, fine- to medium-grained, well-layered gneiss containing oligoclase, clinopyroxene, variable amounts of quartz, and trace amounts of opaque minerals and titanite. Some phases contain scapolite and calcite. Commonly interlayered with pyroxene amphibolite or marble.

Mafic gneiss (Middle to Early Mesoproterozoic) at surface, covers < 0.1 % of this area

Dark-gray to black, fine-grained, magnetite-garnet-hornblende-biotite-diopside-plagioclase gneiss, commonly containing beds of dark-gray vitreous magnetite-garnet quartzite, 2 to 5 cm thick, tremolite-pyroxene gneiss, and biotite-rich, rusty-weathering garnet-quartz schist and gray sulfidic sillimanite quartzite. Occurs as screens within tonalitic gneiss and the Pharaoh Mountain Gneiss and is interpreted as paragneisses older than the tonalitic gneiss (Y2bt). Paragneiss. Rocks of the Adirondacks in Vermont and in the Whitehall, N.Y., area.

Quartz-Oligoclase Gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

White-weathering, light-greenish-gray, medium- to coarse-grained, moderately layered to indistinctly foliated gneiss and lesser amounts of granofels composed of quartz, oligoclase or andesine, and, locally, biotite, hornblende and (or) clinopyroxene. Contains thin amphibolite layers.

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.

Manhattan Schist (Lower Cambrian and (or) Late Proterozoic) at surface, covers < 0.1 % of this area

(Hall, in press) - Medium-dark gray, medium- to coarse-grained schist and gneiss composed of biotite, muscovite, quartz, and plagioclase, and local accessory minerals sillimanite, kyanite, tourmaline, and garnet. Contains some interlayered amphibolite. Unit is not exposed in the map area, but is present in boring logs.

Leithsville Formation (Middle and Lower Cambrian) at surface, covers < 0.1 % of this area

(Wherry, 1909) - Thin- to thick-bedded dolomite containing subordinate siliciclastic rocks. Upper part is medium- to medium-dark-gray, fine- to medium-grained, pitted, friable, mottled and massive dolomite. Middle part is medium-gray, stylolitic, fine-grained, thin- to medium-bedded dolomite that is interbedded with shaly dolomite and, less commonly, vari-colored quartz sandstone, siltstone, and shale. Lower part is medium-gray, medium-grained, medium-bedded dolomite containing quartz-sand grains in stringers and lenses near the contact with the Hardyston Quartzite. Archaeocyathids of Early Cambrian age suggest an intraformational disconformity separating rocks of Middle and Early Cambrian age (Palmer and Rozanov, 1976). Thickness approximately 305 m (1,000 ft).

Bloomsburg Red Beds (Upper Silurian) at surface, covers < 0.1 % of this area

(White, 1883) (High Falls Shale of previous usage) - Grayish-red, thin- to thick-bedded, poorly to moderately well sorted, massive siltstone, sandstone, and local quartz-pebble conglomerate containing local planar to trough crossbedded laminations. Conglomerate consists of matrix-supported quartz pebbles in grayish-red, fine-grained sandstone matrix. Locally, near base of unit, is greenish-gray, light-gray, or grayish-orange, massive, planar tabular to trough crossbedded quartz sandstone to siltstone with subrounded grains. Lower part of formation marked by several upward-fining sequences of light-gray sandstone grading through grayish-red, fine-grained sandstone and siltstone to grayish-red, mudcracked siltstone and mudstone. Each sequence is 1 to 3 m (3-10 ft) thick. Lower contact placed at bottom of lowermost red sandstone. Thickness approximately 460 m (1,510 ft).

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

Succession of grayish-red sandstone, siltstone, shale, and mudstone, generally in fining-upward cycles; some gray sandstone and conglomerate.

Mount Eve Granite (Middle Proterozoic) at surface, covers < 0.1 % of this area

(Drake and others, 1991a) - Light-pinkish-gray or grayish-tan-weathering, light-gray to pinkish-gray, medium- to coarse-grained granite containing microcline microperthite, quartz, oligoclase, and biotite. Common accessory minerals include hornblende, biotite, magnetite, and allanite. Most of the rock is a syenogranite. Upper intercept U-Pb age of 1,020ñ4 Ma (Drake and others, 1991a). Occurs in Pochuck Mountain area along New York boundary.

Hardyston Quartzite (Lower Cambrian) at surface, covers < 0.1 % of this area

(Wolff and Brooks, 1898) - Medium- to light-gray, fine- to coarse-grained, medium- to thick-bedded quartzite, arkosic sandstone and dolomitic sandstone. Basal pebble to cobble conglomerate typically contains clasts of local basement affinities. Contains fragments of the trilobite Olenellus thompsoni of Early Cambrian age. Thickness approximately 0.5 to 62 m (1.6-200 ft).

Green Pond Conglomerate (Lower (?) and Middle Silurian) at surface, covers < 0.1 % of this area

(Rogers, 1836) - Medium- to coarse-grained quartz-pebble conglomerate, quartzitic arkose and orthoquartzite, and thin- to thick-bedded reddish-brown siltstone. Grades downward into gray, very dark-red, or grayish-purple, medium- to coarse-grained, thin- to very thick bedded pebble to cobble conglomerate containing clasts of red shale, siltstone, and chert; yellowish-gray sandstone and chert; dark-gray shale and chert; and white-gray and pink milky quartz. Quartz cobbles are as long as 10 cm (4 in.), and rare red shale clasts as much as 46 cm (18 in.) across. Milky quartz pebbles average 2.5 cm (1 in.) in length. Red arkosic quartz-pebble conglomerate and quartzite are more abundant than gray and grayish-green quartzite. Unconformably overlies Martinsburg Formation, Allentown Dolomite, Leithsville Formation, or Proterozoic rocks. About 305 m (1000 ft) thick.

Moosalamoo Formation - gray phyllite and metawacke member (Lower Cambrian and Neoproterozoic) at surface, covers < 0.1 % of this area

Dark-gray, sooty-weathering, splintery sulfidic to non-sulfidic quartz phyllite and pebbly and gritty biotite metawacke. Cover rocks of the Lincoln Mountain massif and northwestern flank of the Green Mountain massif.

Skunnemunk Conglomerate (Middle Devonian) at surface, covers < 0.1 % of this area

(Darton, 1894) - Grayish-purple to grayish-red, thin- to very thick bedded, locally cross-bedded, polymictic conglomerate and sandstone containing clasts of white vein quartz, red and green quartzite and sandstone, red and gray chert, and red shale; interbedded with medium-gray, thin-bedded sandstone and greenish-gray and grayish-red, mud-cracked shale. Conglomerate and sandstone matrix is primarily hematite and microcrystalline quartz. Conglomerate cobbles range to 16.5 cm (6.5 in) long, and average cobble size increases in upper part of unit. Lower contact conformable and gradational as defined by Kummel and Weller (1902). About 915 m (3,000 ft) thick.

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

Interbedded olive-gray mudstone, siltstone, sandstone, and thin conglomerate; marine fossils throughout; "Chemung" of earlier workers. Laterally equivalent to Scherr and Foreknobs Formations.

Bellvale Sandstone (Middle Devonian) at surface, covers < 0.1 % of this area

(Bellvale Flags of Darton, 1894; Willard, 1937) - Upper beds are grayish-red to grayish-purple sandstone containing quartz pebbles as large as 3 cm (1.2 in) in diameter. Lower beds are light-olive-gray- to yellowish-gray- and greenish-black-weathering, medium-gray to medium-bluish-gray very thin to very thick bedded siltstone and sandstone cross-bedded, graded and interbedded with black to dark-gray shale that is locally fossiliferous. More sandstone in upper beds becomes finer downward. Lower contact conformable and placed where beds thicken and volume of shale and siltstone are about equal. The unit is 535 to 610 m (1,750-2,000 ft) thick.

Kanouse and Esopus Formations and Connelly Conglomerate, undivided (Lower Devonian) at surface, covers < 0.1 % of this area

Kanouse Sandstone (Kmmel, 1908) - Medium-gray, light-brown, and grayish-red, fine- to coarse-grained, thin- to thick-bedded sparsely fossiliferous sandstone and pebble conglomerate. Basal conglomerate beds are interbedded with siltstone similar to the upper part of the Esopus Formation and contain well-sorted, subangular to subrounded, gray and white quartz pebbles less than 1 cm (0.4 in.) long. Lower contact gradational. About 14 m (46 ft) thick. Esopus Formation - (Vanuxem, 1842; Boucot, 1959) - Light- to dark-gray, laminated to thin-bedded siltstone interbedded with dark-gray to black mudstone, dusky-blue sandstone and siltstone, and yellowish-gray fossiliferous siltstone and sandstone. Lower contact probably conformable with the Connelly Conglomerate. The formation is about 100 m (330 ft) thick at Greenwood Lake and estimated at 55 m (180 ft) thick in Longwood Valley. Connelly Conglomerate (Chadwick, 1908) - Grayish-orange weathering, very light gray to yellowish-gray, thin-bedded quartz-pebble conglomerate. Quartz pebbles average 1 to 2 cm (0.4-0.8 in.), are subrounded to well rounded, and well sorted. The unit unconformably overlies the Berkshire Valley Formation. About 11 m (36 ft) thick.

Passaic Formation Sandstone and Siltstone facies (Lower Jurassic and Upper Triassic) at surface, covers < 0.1 % of this area

Sandstone (JTrps) is interbedded grayish-red to brownish-red, medium- to fine-grained, medium- to thick-bedded sandstone and brownish-to-purplish-red coarse-grained siltstone; unit is planar to ripple cross-laminated, fissile, locally calcareous, containing desiccation cracks and root casts. Upward-fining cycles are 1.8 to 4.6 m (6-15 ft) thick. Sandstone beds are coarser and thicker near conglomerate units (JTrpcq, JTrpcl). Maximum thickness about 1,100 m (3,610 ft).

Potassic Feldspar Gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Light-gray- to pinkish-buff-weathering, pinkish-white to light-pinkish-gray, fine- to medium-grained, moderately foliated gneiss and lesser amounts of granofels composed of quartz, microcline, microcline microperthite and local accessory amounts of biotite, garnet, sillimanite, and opaque minerals.

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

Gray- to buff- or white-weathering, greenish-gray, medium- to coarse-grained, massive, gneissoid to indistinctly foliated granite containing mesoperthite to microantiperthite, quartz, oligoclase, and clinopyroxene. Common accessory minerals include titanite, magnetite, apatite, and trace amounts of pyrite. Some phases are monzonite, quartz monzodiorite, or granodiorite. Locally includes small bodies of amphibolite not shown on map.

Biotite-quartz-oligoclase gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

White- to light-gray-weathering, light- to medium-gray or greenish-gray, fine- to coarse-grained, massive to moderately well layered, foliated gneiss composed of oligoclase or andesine, quartz, biotite, and, locally, garnet. Commonly interlayered with amphibolite.

Pegmatite dikes (Late Mesoproterozoic) at surface, covers < 0.1 % of this area

Pinkish-gray to light-gray, unfoliated, magnetite-biotite (±tourmaline) granite pegmatite, <1 m to 10 m thick. Crosscuts Ottawan foliation and locally fills narrow, northeast-trending, steeply dipping normal ductile shear zones. Intrusive rocks of the Adirondacks in Vermont and in the Whitehall, N.Y., area.

Clinopyroxene-Quartz-Feldspar Gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Pinkish-gray- or pinkish-buff-weathering, white to pale-pinkish-white or light-gray, fine- to medium-grained, massive to moderately well-layered gneiss composed of microcline, quartz, oligoclase, clinopyroxene, and trace amounts of epidote, biotite, titanite, and opaque minerals. Commonly interlayered with amphibolite or pyroxene amphibolite.

Beekmantown Group, Lower Part (Lower Ordovician) at surface, covers < 0.1 % of this area

(Clarke and Schuchert, 1899) - Very thin to thick-bedded, interbedded dolomite and minor limestone. Upper beds are light-olive-gray to dark-gray, fine- to medium-grained, thin- to thick-bedded dolomite. Middle part is olivegray-, light-brown-, or dark-yellowish-orange- weathering, dark-gray, aphanitic to fine-grained, laminated to medium-bedded dolomite and light-gray to light-bluish-gray-weathering, medium-dark- to dark-gray, fine-grained, thin- to medium-bedded limestone, that is characterized by mottling with reticulate dolomite and light-olive-gray to grayish-orange, dolomitic shale laminae surrounding limestone lenses. Limestone grades laterally and down section into medium- gray, fine-grained dolomite. Lower beds consist of medium-light- to dark-gray, aphanitic to coarse-grained, laminated to medium-bedded, locally slightly fetid dolomite having thin black chert beds, quartz-sand laminae, and oolites. Lenses of light-gray, very coarse to coarse-grained dolomite and floating quartz sand grains and quartz-sand stringers at base of sequence. Lower contact placed at top of distinctive medium-gray quartzite. Contains conodonts of Cordylodus proavus to Rossodus manitouensis zones of North American Midcontinent province as used by Sweet and Bergstrom (1986). Unit Obl forms Stonehenge Formation of Drake and Lyttle (1985) and Drake and others (1985), upper and middle beds are included in Epler Formation, and lower beds are in Rickenbach Dolomite of Markewicz and Dalton (1977). Unit is about 183 m (600 ft) thick.

Serpentinite (Cambrian and Late Proterozoic) at surface, covers < 0.1 % of this area

Light-yellowish-green to dark-green, fine-grained, massive serpentinite containing locally abundant magnetite where fresh. Contains a variety of serpentine minerals and alteration products where sheared or weathered. Exposed only along the Hudson waterfront in Hoboken but present elsewhere in boring logs.

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

(Hartnagel, 1907) - Black to dark-gray, very-thin- to thickbedded, fissile shale, fossiliferous, interbedded with medium-gray and light-olive-gray to yellowish-gray, laminated to very-thin-bedded siltstone, that increases in upper part of unit. Lower contact probably conformable. About 290 m (950 ft) thick.

Biotite-Quartz-Feldspar Gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Gray-weathering, locally rusty, gray to tan or greenish-gray, fine- to medium-coarse-grained, moderately layered and foliated gneiss that is variable in texture and composition. Composed of oligoclase, microcline microperthite, quartz, and biotite. Locally contains garnet, graphite, sillimanite, and opaque minerals.

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

Gray- to grayish-black, medium-grained amphibolite composed of hornblende and andesine. Some phases contain biotite and (or) clinopyroxene. Ubiquitous and associated with almost all other Middle Proterozoic units. Some amphibolite is clearly metavolcanic in origin, some is metasedimentary, and some appears to be metagabbro.

Berkshire Valley and Poxono Island Formations, undivided (Upper Silurian) at surface, covers < 0.1 % of this area

Thickness ranges from 76 m (250 ft) at Greenwood Lake to 122 m (400 ft) in Longwood Valley. Berkshire Valley Formation (Barnett, 1970) - Commonly yellowish-gray weathering, medium-gray to pinkish-gray, very thin to thin-bedded fossiliferous limestone interbedded with gray to greenish-gray calcareous siltstone and silty dolomite, medium-gray to light-gray dolomite conglomerate, and grayish-black, thinly laminated shale. Lower contact conformable. Thickness ranges from 27 to 38 m (90-125 ft) thick. Poxono Island Formation, (White, 1882; Barnett, 1970) - Very thin to medium-bedded sequence of medium-gray, greenish-gray, or yellowish-gray, mud-cracked dolomite; light-green, pitted, medium-grained calcareous sandstone, siltstone, and edgewise conglomerate containing gray dolomite; and quartz-pebble conglomerate containing angular to subangular pebbles as much as 2 cm (0.8 in.) long. Interbedded grayish-green shales at lower contact are transitional into underlying Longwood Shale. Thickness ranges from 49 to 84 m (160-275 ft) thick.

Vesicular basalt breccia at East Hoosick (Upper Ordovician) at surface, covers < 0.1 % of this area

In the Walloomsac Formation; perhaps intrusive. Part of the Taconic Allochthon. Wildflysch-like conglomerates within the Hortonville, Ira, and Walloomsac Formations occur as local areas of black slate rich in inclusions of quartzite, greenish-gray slate, wacke, and punky-weathering bluish-gray limestone, interpreted as sedimentary breccias, deposited in front of the advancing Taconic allochthon (Upper Ordovician) (Zen, 1961; Potter, 1972; Fisher, 1985). Exposed near the western and northern margin of the allochthon and in the Bennington area at the type Whipstock. Here and at many localities the Forbes Hill and Whipstock breccias are tectonic breccias formed in situ by disruption of thin to thick beds, laminae, and carbonate-quartz-sulfide veins rather than clastic sedimentary rocks. The cleavage and related folding commonly is a late strain-slip cleavage characterized by a strong down-plunge lineation parallel to reclined hingelines of minor folds of foliation and compositional layering. Units are retained although interpretation as sedimentary wildflysch deposits is in part questionable.

Hornblende-Quartz-Feldspar Gneiss (Middle Proterozoic) at surface, covers < 0.1 % of this area

Pinkish-gray- to buff-weathering, light- pinkish-white to pinkish-gray, fine- to medium-grained, massive to moderately well layered gneiss containing microcline, quartz, oligoclase, hornblende, and magnetite. Locally contains garnet and biotite.

Poxono Island Formation (Upper Silurian) at surface, covers < 0.1 % of this area

(White, 1882) - Greenish-gray, finely crystalline to aphanitic, thin- to medium-bedded, flaggy dolomite containing discontinuous lenses of disseminated, rounded quartz grains. Some local quartz sandstone beds and argillaceous dolomite. Lower contact gradational (Epstein, 1973). Formation poorly exposed; located by drill data. Thickness estimated at 183 m (600 ft) from well data.

Passaic Formation Conglomerate and Sandstone facies (Lower Jurassic and Upper Triassic) at surface, covers < 0.1 % of this area

Conglomeratic sandstone (JTrpsc) is brownish-red pebble conglomerate, medium- to coarse-grained, feldspathic sandstone and micaceous siltstone; unit is planar to low-angle trough cross laminated, burrowed, and contains local pebble layers. Unit forms upward-fining sequences 0.5 to 2.5 m (1.6-8 ft) thick. Conglomeratic sandstone thickness exceeds 800 m (2,625 ft).

Everett Formation (Lower Cambrian and Proterozoic Z) at surface, covers < 0.1 % of this area

Light-green and greenish-gray chlorite-muscovite-albite or chloritoid-rich phyllite. Predominantly dark-gray chloritoid-rich schist in Lenox Mountain.

Pottsville Formation (Pennsylvanian) at surface, covers < 0.1 % of this area

Predominantly gray sandstone and conglomerate; also contains thin beds of shale, claystone, limestone, and coal; includes Olean and Sharon conglomerates of northwestern Pennsylvania; thin marine limestones present in Beaver, Lawrence, and Mercer Counties; minable coals and commercially valuable high-alumina clays present locally.

Rondout and Decker Formations, undivided (Lower Devonian and Upper Silurian) at surface, covers < 0.1 % of this area

Rondout Formation (Clarke and Schuchert, 1899) - Upper part is medium-gray weathering, medium-dark-gray, very fine to fine-grained, medium-bedded, fossiliferous, argillaceous limestone. Middle part is light-medium-gray-weathering, medium-gray, laminated to medium-bedded, argillaceous dolomite. Locally contains deep desiccation polygons. Lower part is medium-gray-weathering, medium- to dark-gray, very fine to medium-grained, medium-bedded fossiliferous limestone. Silurian-Devonian boundary placed in middle of formation (Denkler and Harris, 1988). Lower contact abrupt and placed at top of highest calcareous quartz sandstone. Thickness approximately 12 m (40 ft). Decker Formation (White, 1882) - Light-gray- to yellowish-gray-weathering, light- to medium-gray, calcareous quartz siltstone, sandstone, and fine-pebble conglomerate locally interbedded with fossiliferous medium-gray, medium- to coarse-grained limestone and very fine grained, thin- to medium-bedded dolomite. Lower contact gradational. Thickness varies from 15 m (50 ft) near Duttonville to 25 m (82 ft) at Wallpack Center.

Coeymans Formation, Kalkberg Limestone, Coeymans Limestone, Manlius Limestone, undivided (Lower Devonian) at surface, covers < 0.1 % of this area

At New York border consists of fine-grained, chert-bearing, argillaceous limestone (Kalkberg Limestone) grading downward through coarse-grained limestone (Coeymans Limestone) into fine-grained limestone (Manlius Limestone). Toward southwest these units grade into fine- to coarse-grained limestone with a marked increase in quartz sand that comprises the Coeymans Formation (Epstein and others, 1967). Total thickness 27 m (90 ft). Coeymans Formation (Epstein and others, 1967) - Medium-light-gray, fine- to coarse-grained calcareous sandstone and medium-gray, fine- to coarse-grained, medium- to thick-bedded, locally irregularly-bedded, argillaceous to arenaceous limestone containing lenses of quartz sand and nodules of black chert. Grades downward into medium-gray, fine-grained, argillaceous and arenaceous limestone containing local beds of fine- to coarse-grained pebbly calcareous sandstone. Local bioherms consisting of light-gray to light-pinkish-gray, coarse-grained to very coarse biogenic limestone are unbedded and have sharp boundaries. Lower contact of unit abrupt. Formation thickness varies from 11 m (35 ft) in northeast to 24 m (80 ft) in southwest. Kalkberg Limestone (Chadwick, 1908) - Medium-gray-weathering, medium-dark-gray, fine-grained, very thin to massively bedded fossiliferous limestone. Grades downward into fine- to medium-grained, thin-bedded, fossiliferous argillaceous limestone containing nodules and lenses of dark-gray chert. Grades to the southwest into calcareous and arenaceous rocks of the upper part of the Coeymans Formation near Wallpack Center. Lower contact placed at base of lowest black chert. Approximately 12 m (40 ft) thick. Coeymans Limestone (Clarke and Schuchert, 1899) - Medium-gray weathering, medium-dark-gray, fine-to-coarse-grained, medium- to massively bedded fossiliferous limestone and local argillaceous limestone lenses. Unit is approximately 9 m (30 ft) thick. Between Duttonville and Millville, grades into biohermal and nonbiohermal facies of medium- to coarse-grained limestone of Coeymans Formation of Epstein and others (1967). Manlius Limestone (Vanuxem, 1840) - Medium-gray weathering, medium-dark- to dark-gray, very fine to fine-grained, unevenly bedded fossiliferous limestone. Some local medium-grained limestone, yellowish-gray shale partings and biostromes. Near Hainesville, unit grades into lower part of Coeymans Formation. Lower contact abrupt and placed at top of uppermost very fine grained argillaceous limestone. Thickness approximately 11 m (35 ft).

Minisink Limestone and New Scotland Formation, undivided (Lower Devonian) at surface, covers < 0.1 % of this area

Minisink Limestone (Epstein and others, 1967) - Light-medium-gray-weathering, medium-gray, fine-grained, medium-bedded, partly massive, argillaceous fossiliferous limestone. Some nodules and lenses of purer limestone occur locally. Lower contact gradational. Thickness uniformly 7 m (23 ft). New Scotland Formation (Clarke and Schuchert, 1899) - Upper part is dark-gray, very fine grained, laminated to thin-bedded siliceous shale containing pods of medium-dark-gray, very fine grained limestone; scattered thin beds and lenses of medium-gray, fine-grained argillaceous fossiliferous limestone; and small dark-gray chert nodules. Lower part is medium-dark-gray, thin-bedded, siliceous, fossiliferous calcareous shale. Contains thin beds and lenses of medium-gray, fine-grained, highly fossiliferous, argillaceous limestone containing nodules, lenses and, locally, irregular beds of dark-gray chert. Lower contact abrupt and placed at top of calcareous quartz sandstone. Total thickness is approximately 23 m (75 ft).

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

(White, 1882) - Light-gray to yellowish- gray-weathering, medium-gray to medium-dark-gray, very fine grained, locally fossiliferous, laminated to thin-bedded limestone and argillaceous limestone. Desiccation polygons occur in southwest. Lower contact is gradational and placed at top of uppermost dolomite. Thickness approximately 30 m (100 ft) in southwest, thinning to 3.1 m (10 ft) at New Jersey-New York State boundary.