|Name||Collins Hill Formation|
|Geologic age||Upper? and Middle Ordovician|
Metamorphic > SchistGray, rusty-weathering, medium- to coarse-grained, poorly layered schist, composed of quartz, oligoclase, muscovite, biotite, and garnet, and commonly staurolite, kyanite, or sillimanite, generally graphitic.
Metamorphic > Gneissinterlayered with fine-grained two-mica gneiss, especially to the west
Metamorphic > Metasedimentary > Calc-silicate-rockcalc-silicate and rare quartz-spessartine (coticule) layers
Metamorphic > Amphibolite
|Comments||Part of Eastern Uplands; Iapetus (Oceanic) Terrane - Bronson Hill Anticlinorium; Brimfield Schist and equivalent formations (includes Collins Hill Formation) (Upper? and Middle Ordovician).|
Rodgers, John, compiler, 1985, Bedrock Geological Map of Connecticut: Connecticut Geological and Natural History Survey, Hartford, Connecticut, 2 sheets, scale 1:125,000.
|Counties||Hartford - Middlesex - New Haven - Tolland|