Rhode Island Formation

Sandstone, graywacke, shale and conglomerate; minor beds of meta-anthracite. Fossil plants. Rhode Island Formation is thickest and most extensive formation in Narragansett basin. Does not extend to Norfolk basin. Consists of gray sandstone and siltstone and lesser amounts of gray to black shale, gray conglomerate, and coal beds 10 m thick. Interfingers with Wamsutta Formation in Narragansett basin. In places overlies Dedham Granite. Age is Middle and Late Pennsylvanian (Goldsmith, 1991).
State Massachusetts
Name Rhode Island Formation
Geologic age Upper and Middle Pennsylvanian
Lithologic constituents
Sedimentary > Clastic > Sandstone
Sedimentary > Clastic > Sandstone > Graywacke
Sedimentary > Clastic > Conglomerate
Sedimentary > Clastic > Mudstone > Shalesome black shale
Sedimentary > Coal > Anthracite (Bed)meta-anthracite
Comments Part of Milford-Dedham Zone (Tertiary and Older Rocks). Secondary unit description per MA023.
NGMDB product
Counties Bristol - Norfolk - Plymouth