| State |
Massachusetts |
| Name |
Portland Formation |
| Geologic age |
Lower Jurassic |
| Lithologic constituents |
Major
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Sandstone > Arkose (Bed)
Minor
Sedimentary > Clastic > Mudstone > Shale > Black-shale (Bed)
Sedimentary > Clastic > Sandstone (Bed)
|
| Comments |
Part of Mesozoic Basins (Jurassic and Triassic Rocks); Sedimentary and Volcanic Rocks of Hartford Basin. Secondary unit description per MA003 as reported in USGS Geologic Names lexicon (Rf. MA024): Assigned to Newark Supergroup. Upper part may be Middle Jurassic according to Cornet (1977) (Robinson and Luttrell, 1985). |
| 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 Robinson, Peter and Luttrell, G.W., 1985, Revision of some stratigraphic names in central Massachusetts, IN Stratigraphic notes, 1984: U.S. Geological Survey Bulletin, 1605-A, p. A71-A78.
https://pubs.er.usgs.gov/publication/b1605A USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/Geolex/
https://ngmdb.usgs.gov/Geolex/search
|
| NGMDB product |
|
| Counties |
Hampden - Hampshire
|
