Walloomsac Formation

Phyllite, schist, metagraywacke.
State New York
Name Walloomsac Formation
Geologic age Middle Ordovician
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > Phyllite
Metamorphic > Schist
Metamorphic > Metasedimentary > Metaclastic > Metasandstone > Metagraywacke
Comments part of Trenton Group and Metamorphic Equivalents up to 8000 ft. (2400 m).
References

Fisher, D.W., Isachsen, Y.W., and Rickard, L.V., 1970, Geologic Map of New York State, consisting of 5 sheets: Niagara, Finger Lakes, Hudson-Mohawk, Adirondack, and Lower Hudson, New York State Museum and Science Service, Map and Chart Series No. 15, scale 1:250,000.

NGMDB product
Counties Columbia - Dutchess - Putnam