Unit c [of Stockbridge Marble] (CTCAsc;0)

State	Connecticut
Name	Unit c [of Stockbridge Marble]
Geologic age	Upper Cambrian
Original map label	Csc
Comments	Part of Western Uplands; Proto-North American (Continental) Terrane - Carbonate Shelf Secondary unit description from USGS Geologic Names lexicon (ref. CT017): Revised as Stockbridge Formation, a heterogeneous rock group that may be mapped as seven lithostratigraphic units A through G (ascending). Highest bed as mapped by Dale (1923) is interbedded with overlying schist and is reassigned to Walloomsac Formation. Units A, B, and C are mostly dolostone and include important beds of arkose and phyllite. Units D and F are heterogeneous rocks consisting of silty limestone, dolostone, calcite marble, phyllite, and calcareous sandstone. Sandstone shows cross-stratification that allows determination of the top of bedding. Units E and G are massive, white to gray calcite marble that include interbedded pale, massive, fine-grained dolostone. Because of this heterogeneity, the name is revised to Stockbridge Formation. Excellent exposures may be seen at Vossburg Hill and on hillside south of South Egremont village in Egremont quad, MA and NY. Yields no fossils but overlies Cheshire Quartzite of Early Cambrian age and underlies Middle Ordovician Walloomsac Formation; therefore, the Stockbridge spans the age between Early Cambrian and Early or Middle Ordovician.
Primary rock type	marble
Secondary rock type	sandstone
Other rock types
Lithologic constituents	Major Metamorphic > Metasedimentary > Metacarbonate > MarbleGray, generally massive dolomite marble, commonly contains quartz grains. Minor Sedimentary > Clastic > Sandstonelocally beds of sandstone; may be calcitic near top
Map references	Connecticut Geological and Natural History Survey, DEP, in cooperation with the U.S. Geological Survey, 2000, Bedrock Geology of Connecticut, data format: shapefile, file name: bedrock, downloaded from: http://magic.lib.uconn.edu/cgi-bin/MAGIC_DBsearch2.pl?Geography=37800&Loc=0000 on 9/18/2003, scale 1:50,000. [http://magic.lib.uconn.edu/connecticut_data.html#environmental] [http://magic.lib.uconn.edu/cgi-bin/MAGIC_DBsearch2.pl?Geography=37800&Loc=0000]
Unit references	Rodgers, John, compiler, 1985, Bedrock Geological Map of Connecticut: Connecticut Geological and Natural History Survey, Hartford, Connecticut, 2 sheets, scale 125,000. USGS Geologic Names Lexicon (GEOLEX) [http://ngmdb.usgs.gov/Geolex/]
Geographic coverage	Litchfield