Upper member [of Middletown Formation]

Light-gray, generally rusty weathering, well-layered gneiss and granofels, composed of oligoclase, quartz, biotite, and amphibole (cummingtonite, anthophyllite, gedrite, or hornblende, or several of these), also garnet and chlorite. Many layers of amphibolite and biotite gneiss throughout.
State Connecticut
Name Upper member [of Middletown Formation]
Geologic age Middle Ordovician
Lithologic constituents
Major
Metamorphic > Granoblastic > GranofelsLight-gray, generally rusty weathering, well-layered gneiss and granofels, composed of oligoclase, quartz, biotite, and amphibole (cummingtonite, anthophyllite, gedrite, or hornblende, or several of these), also garnet and chlorite.
Metamorphic > GneissLight-gray, generally rusty weathering, well-layered gneiss and granofels, composed of oligoclase, quartz, biotite, and amphibole (cummingtonite, anthophyllite, gedrite, or hornblende, or several of these), also garnet and chlorite; also biotite gneiss.
Minor
Metamorphic > Amphibolite
Comments Part of Eastern Uplands; Iapetus (Oceanic) Terrane - Bronson Hill Anticlinorium
References

Rodgers, John, compiler, 1985, Bedrock Geological Map of Connecticut: Connecticut Geological and Natural History Survey, Hartford, Connecticut, 2 sheets, scale 1:125,000.

NGMDB product
Counties Middlesex