Dalton Formation

(Including Poughquag and Lowerre Formation) - Gray, tan-weathering, medium-grained, generally well layered gneiss or feldspathic quartzite, composed of quartz, microcline, plagioclase, muscovite, biotite, and generally tourmaline; some schistose micaceous layers have sillimanite; commonly as quartz-sillimanite nodules rimmed with muscovite. Layers of purer quartzite in many areas, especially near the top or where the formation is thin.
State Connecticut
Name Dalton Formation
Geologic age Lower Cambrian and perhaps partly older
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > Quartzitefeldspathic quartzite; layers of purer quartzite in many areas, especially near the top or where the formation is thin.
Metamorphic > GneissComposed of quartz, microcline, plagioclase, muscovite, biotite, and generally tourmaline; some schistose micaceous layers have sillimanite; commonly as quartz-sillimanite nodules rimmed with muscovite.
Comments Part of Western Uplands; Proto-North American (Continental) Terrane - Carbonate Shelf
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 Fairfield - Litchfield