State | Connecticut |
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Name | Shelton Member [of Trap Falls Formation] |
Geologic age | Middle or Lower Ordovician |
Lithologic constituents |
Major
Metamorphic > GneissWhite, light-gray, or buff, fine- to medium-grained, generally well foliated granitic gneiss, composed of sodic plagioclase, quartz, microcline, muscovite, and garnet (in tiny almost ubiquitous grains), also commonly minor biotite. Generally interlayered with biotite gneiss.
Minor
Metamorphic > Schist > Mica-schistgenerally interlayered with mica schist
Incidental
Metamorphic > Metasedimentary > Calc-silicate-rockgenerally interlayered with calc-silicate rock
|
Comments | Part of Central Lowlands; Iapetus (Oceanic) Terrane - Connecticut Valley Synclinorium; Hartland Belt. Part of Hawley Formation and equivalent formations (includes Trap Falls and Cobble Mountain Formations) (Middle Ordovician). Secondary unit description per CT007. |
References | Rodgers, John, compiler, 1985, Bedrock Geological Map of Connecticut: Connecticut Geological and Natural History Survey, Hartford, Connecticut, 2 sheets, scale 1:125,000.Sevigny, J.H. and Hanson, G.N., 1993, Orogenic evolution of the New England Appalachians of southwestern Connecticut: Geological Society of America Bulletin, v. 105, no. 12, p. 1591-1605. |
NGMDB product | |
Counties | Fairfield |