Walloomsac Formation

Tan to dark-blue-gray laminated quartzite and calcareous quartzite previously mapped as Bellowspipe Quartzite.
State Massachusetts
Name Walloomsac Formation
Geologic age Middle Ordovician
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > QuartziteTan to dark-blue-gray laminated quartzite and calcareous quartzite previously mapped as Bellowspipe Quartzite.
Comments Part of Taconic-Berkshire Zone (Ordovician and Older Rocks). Thin limestone unit near base of Walloomsac locally contains abundant bryozoan fragments, cup corals, pelmatozoan hash, and conodonts that indicate that the base of the Walloomsac is Rocklandian (middle and late Caradocian) or younger. Age of unit is Middle Ordovician per MA011.
References
NGMDB product
Counties Berkshire