|Geologic age||Middle Ordovician|
|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.|
|Primary rock type||limestone|
|Secondary rock type|
|Other rock types|
Sedimentary > Carbonate > Limestone (Lense)Blue-gray and white mottled crystalline limestone lenses near base of the Walloomsac locally yielding fragments of pelmatozoa, bryozoa and cup coral.
Unpublished Digital Geologic Map of Massachusetts received from Rudi Hon at Boston College in 1998.
Zen, E-An (ed.), Goldsmith, R. (comp.), Ratcliffe, N.M. (comp.), Robinson, P. (comp.), Stanley, R.S. (comp.), Hatch, N.L., Jr., Shride, A.F., Weed, E.G.A., Wones, D.R., 1983, Bedrock Geologic Map of Massachusetts: U.S. Geological Survey, Reston, VA, scale 1: 250,000.