Hoppin Formation

Quartz arenite, argillite, and minor limestone; contains fossils of Lower Cambrian age.
State Rhode Island
Name Hoppin Formation
Geologic age Cambrian
Lithologic constituents
Sedimentary > Clastic > Sandstone > Arenitequartz arenite
Metamorphic > Metasedimentary > Metaclastic > Argillite
Sedimentary > Carbonate > Limestone
Comments Part of Esmond-Dedham Subterrane (West Bay Area). Secondary unit description from USGS Geologic Names lexicon (ref. RI013): Hoppin Formation consists of green and red slaty shale, locally containing calcareous nodules, and lenses of red argillaceous limestone; arkosic quartzite (locally conglomeratic) and sandstone occur at base of formation. Nonconformity at base of formation over Dedham Granite is clearly exposed at Hoppin Hill; Early Pennsylvanian Pondville Conglomerate lies with angular unconformity above. Maximum thickness is approx 244 m. Age is Early and Middle Cambrian. Report includes geologic maps, measured sections, and correlation charts. [Chapters A-J in U.S. Geological Survey Professional Paper 1366 are intended as explanations and (or) revisions to 1:250,000-scale MA State bedrock geologic map of Zen and others (1983).] Source: GNU records (USGS DDS-6; Reston GNULEX).

Hermes, O.D. (comp.), Gromet, L.P. (comp.), Murray, D.P. (comp.), Hamidzada, N.A., Skehan, J.W., and Mosher, S., 1994, Bedrock geologic map of Rhode Island: Rhode Island Map Series No. 1, Kingston, Rhode Island, scale 1:100,000.

USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/Geolex/


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Counties Providence