| State |
Massachusetts |
| Name |
Walloomsac Formation |
| Geologic age |
Middle Ordovician |
| Lithologic constituents |
Major
Metamorphic > Schistgraphitic quartz phyllite and schist
Metamorphic > Metasedimentary > Metaclastic > Phyllitegraphitic quartz phyllite and schist
Minor
Sedimentary > Carbonate > Limestone (Lens)
|
| 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 |
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., and Wones, D.R., 1983, Bedrock Geologic Map of Massachusetts: U.S. Geological Survey, Reston, VA, scale 1: 250,000.
https://pubs.er.usgs.gov/publication/70046713 Ratcliffe, N.M., Potter, D.B. and Stanley, R.S., 1993, Bedrock geologic map of the Williamstown and North Adams quadrangles, Massachusetts and Vermont, and part of the Cheshire quadrangle, Massachusetts: U.S. Geological Survey Miscellaneous Investigations Series Map, I-2369, 13 p., 2 sheets, scale 1:24,000.
https://pubs.er.usgs.gov/publication/i2369
|
| NGMDB product |
|
| Counties |
Berkshire - Hampden
|
