Hoppin Formation

Quartzite, argillite, and minor limestone; contains Middle Cambrian fauna.
State Massachusetts
Name Hoppin Formation
Geologic age Middle and Lower Cambrian
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > Argillite
Minor
Sedimentary > Carbonate > Limestone
Metamorphic > Metasedimentary > Metaclastic > Quartzite
Comments Part of Milford-Dedham Zone (Tertiary and Older Rocks). Secondary unit description per MA023 as found in USGS Geologic Names lexicon (ref. MA024): 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 (Goldsmith, 1991).
References
NGMDB product
Counties Bristol - Norfolk