Geologic units in Putnam county, New York

Biotite-quartz-plagioclase gneiss (Middle Proterozoic) at surface, covers 26 % of this area

With subordinate biotite granitic gneiss, amphibolite, calcsilicate rock.

Biotite granite gneiss (Middle Proterozoic) at surface, covers 23 % of this area

Overprint signifies inequigranular texture.

Amphibolite (Middle Proterozoic) at surface, covers 21 % of this area

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

Garnet-bearing gneiss and interlayered quartzite (Middle Proterozoic) at surface, covers 12 % of this area

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

Manhattan Formation, undivided (Ordovician?) at surface, covers 6 % 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.

Stockbridge Marble (Cambrian - Lower Ordovician) at surface, covers 3 % of this area

Stockbridge Marble.

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

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

Walloomsac Formation (Middle Ordovician) at surface, covers 2 % of this area

Phyllite, schist, metagraywacke.

Garnet-biotite-quartz-feldspar gneiss (Middle Proterozoic) at surface, covers 1 % of this area

Quartzite, quartz-feldspar gneiss, calcsilicate rock.

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

With subordinate leucogranite.

Inwood Marble (Early Cambrian - Lower Ordovician) at surface, covers 0.7 % of this area

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

Calcitic and dolomitic marble (Middle Proterozoic) at surface, covers 0.4 % of this area

Variably siliceous; in part with calcsilicate rock and amphibolite.

Gabbro or norite to hornblende diorite (Upper Ordovician) at surface, covers 0.4 % of this area

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

Hartland Formation (Ordovician?) at surface, covers 0.2 % of this area

Basal amphibolite overlain by pelitic schists.

Poughquag Quartzite (Cambrian) at surface, covers 0.2 % of this area

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

Manhattan Formation (A Member) (Middle Ordovician) at surface, covers 0.2 % of this area

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

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.

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

Diorite with hornblende and/or biotite.

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.