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Geologic Unit: Rhode Island

Rhode Island Formation (RI*,MA*)
/Rhode Island Group (RI,MA)
[An identical geographic name may not be applied to a unit [Rhode Island Group] and its parts [Rhode Island Formation] (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983).]

Pennsylvanian, Early
Pennsylvanian, Middle*
Pennsylvanian, Late*
Geologic Province:
New England province*

Areal Extent:

Type Locality:
Not designated. Named from fact that it includes graphite coal beds of Rhode Island (Emerson, 1917).

Sachuest Arkose (RI), Purgatory Conglomerate (RI), Pondville Conglomerate (MA,RI), Wamsutta Formation (MA,RI), Rhode Island Formation (RI,MA), and Dighton Conglomerate (MA,RI) of Rhode Island Group (Skehan and Rast, 1990).

Unit Name History:
Named Rhode Island coal measures (Woodworth, 1899).
Revised to Rhode Island Formation (Emerson, 1917).
MA State Geol. Map usage (Zen and others, 1983).
Revised (Skehan and Rast, 1990).
Overview (Goldsmith, 1991).

Note: If you need more information, please contact Nancy Stamm (
Asterisks (*) indicate usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" implies that a name has been abandoned or that it has fallen into disuse. Former usage and, if known, replacement name given in parentheses ().

Slashes (/) indicate unit name usage violates the 1983 North American Stratigraphic Code. This violation may be explained within brackets ([ ]).

U.S. Department of the Interior, U.S. Geological Survey, Reston, VA, USA
Database project personnel
Last modified: 15-Jan-2013