Geologic units in Dutchess county, New York

Walloomsac Formation (Middle Ordovician) at surface, covers 16 % of this area

Phyllite, schist, metagraywacke.

Austin Glen Formation (Middle Ordovician) at surface, covers 15 % of this area

Graywacke, shale

Wappinger Group (Cambrian - Lower Ordovician) at surface, covers 9 % 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.

Stockbridge Marble (Cambrian - Lower Ordovician) at surface, covers 9 % of this area

Stockbridge Marble.

Everett Schist (Cambrian?) at surface, covers 9 % of this area

Locally with minor meta-graywacke lenses.

Normanskill Formation (Middle Ordovician) at surface, covers 8 % of this area

Shale, argillite, siltstone.

Austin Glen Formation (Middle Ordovician) at surface, covers 4 % of this area

Graywacke, shale

Walloomsac Formation (Middle Ordovician) at surface, covers 3 % of this area

Slate, phyllite, schist, metagraywacke.

Nassau Formation (Cambrian?) at surface, covers 3 % of this area

Shale, quartzite.

Biotite granite gneiss (Middle Proterozoic) at surface, covers 3 % of this area

Overprint signifies inequigranular texture.

Elizaville Formation (Cambrian - Ordovician) at surface, covers 3 % of this area

Shale, argillite, quartzite.

Manhattan Formation, undivided (Ordovician?) at surface, covers 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.

Mount Merino and Indian River Formations (Ordovician) at surface, covers 2 % of this area

Shale, argillite, chert.

Stuyvesant Falls Formation (Ordovician) at surface, covers 2 % of this area

Shale, siltstone.

Germantown Formation (Cambrian) at surface, covers 2 % of this area

Shale, limestone, conglomerate.

Poughquag Quartzite (Cambrian) at surface, covers 1 % of this area

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

Briarcliff Dolostone and Pine Plains Formation (Cambrian) at surface, covers 1 % of this area

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

Copake and Rochdale Formations (Lower Ordovician) at surface, covers 1 % of this area

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

Interlayered metasedimentary rock and granitic gneiss (Middle Proterozoic) at surface, covers 1 % of this area

Interlayered metasedimentary rock and granitic gneiss.

Hornblende granite and granite gneiss (Middle Proterozoic) at surface, covers 1 % of this area

With subordinate leucogranite.

Taconic Melange (Middle Ordovician) at surface, covers 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.

Biotite-quartz-plagioclase gneiss (Middle Proterozoic) at surface, covers 0.8 % of this area

With subordinate biotite granitic gneiss, amphibolite, calcsilicate rock.

Briarcliff Dolostone and Pine Plains Formation (Cambrian) at surface, covers 0.4 % of this area

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

Glacial and Alluvial Deposits (Quaternary) at surface, covers 0.4 % of this area

Underlying bedrock geology unknown.

Balmville Limestone (Middle Ordovician) at surface, covers 0.3 % of this area

Balmville Limestone

Stissing Formation (Cambrian) at surface, covers 0.2 % of this area

Dolostone, shale.

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

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

Garnet-bearing gneiss and interlayered quartzite (Middle Proterozoic) at surface, covers 0.2 % of this area

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

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

Quartzite, quartz-feldspar gneiss, calcsilicate rock.

Germantown Formation (Cambrian) at surface, covers 0.2 % of this area

South of Troy; shale, conglomerate, limestone.

Everett Schist (Cambrian?) at surface, covers 0.2 % of this area

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

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

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

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

Shale, slate, cherts.

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

South of Troy; shale, siltstone.

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.

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

Shale, argillite, quartzite.

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.

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.