Geologic units in Fulton county, New York

Glacial and Alluvial Deposits (Quaternary) at surface, covers 23 % of this area

Underlying bedrock geology unknown.

Quartz-feldspar gneiss (Middle Proterozoic) at surface, covers 13 % of this area

With variable amounts of garnet, sillimanite, biotite.

Canajoharie Shale (Middle Ordovician) at surface, covers 12 % of this area

Canajoharie Shale

Biotite and/or hornblende granite gneiss (Middle Proterozoic) at surface, covers 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. Overprint signifies inequigranular texture or phacoidal structure. In northwest Adirondacks, grades into Yphg.

Charnockite, granitic and quartz syenite gneiss (Middle Proterozoic) at surface, covers 8 % 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.

Quartzite, quartz schist and graphitic schist (Middle Proterozoic) at surface, covers 6 % of this area

In part feldspathic, micaceous, garnetiferous, sillimanitic.

Beekmantown Group (Cambrian) at surface, covers 5 % of this area

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

Biotite-quartz-plagioclase gneiss (Middle Proterozoic) at surface, covers 4 % of this area

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

Theresa (Galway) Formation (Cambrian) at surface, covers 4 % of this area

Dolostone, sandstone, shale.

Beekmantown Group (Lower Ordovician) at surface, covers 3 % of this area

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

Trenton and Black River Groups, undivided (Middle Ordovician) at surface, covers 3 % of this area

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

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

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

Pyroxene-hornblende-quartz-plagioclase gneiss (Middle Proterozoic) at surface, covers 2 % of this area

Pyroxene-hornblende-quartz-plagioclase gneiss.

Biotite and/or hornblende granite gneiss (Middle Proterozoic) at surface, covers 2 % 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.

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

Utica Shale

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

Undivided metasedimentary rock and related migmatite.

Potsdam Sandstone (Cambrian) at surface, covers 0.7 % of this area

Potsdam Sandstone

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

Utica Shale

Amphibolite (Middle Proterozoic) at surface, covers 0.3 % of this area

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

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

Metagabbro, olivine metagabbro, derived amphibolite.

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.

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

Chaumont Limestone-chert; Lowville Limestone; Pamelia Dolostone.

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

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