Stamford Gneiss (VTpCAsg;0)

Stamford Gneiss - Granitic biotite gneiss with megacrysts of microcline. A dike-like feature of Stamford Granite, found near eastern margin of Green Mountain massif near locality 1 on this map (represented by sample 172), was incorrectly referred to as a probable Late Proterozoic diabase dike by Ratcliffe on his section of the Bedrock Map of Massachusetts (Zen and others, 1983). U-Pb zircon dates from Karabinos and Aleinikoff (1988, 1990) yield an age of 959+/-4 Ma. Unpublished data from Harding and Mukasa yield a U-Pb zircon date of about 950 Ma (Ratcliffe and others, 1993).

State	Vermont
Name	Stamford Gneiss
Geologic age	Precambrian
Original map label	pCsg
Comments	Part of Plutonic Rocks Secondary unit description per VT004.
Primary rock type	biotite gneiss
Secondary rock type
Other rock types
Lithologic constituents	Major Metamorphic > Gneissgranitic biotite gneiss with megacrysts of microcline
Map references	Nicholson, S.W., Dicken, C.L., Horton, J.D., Foose, M.P., Mueller, J.A.L., and Hon, Rudi, 2006, Preliminary integrated geologic map databases for the United States: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, Rhode Island, and Vermont: U.S. Geological Survey Open-File Report 2006-1272. [http://pubs.er.usgs.gov/publication/ofr20061272]
Unit references	Doll, C.G., Cady, W.M., Thompson, J.B., Jr., and Billings, M.P., 1961, Centennial Geologic Map of Vermont: Vermont Geological Survey, Miscellaneous Map MISCMAP-01, scale 1:250,000. Ratcliffe, N.M., Potter, D.B. and Stanley, R.S., 1993, Bedrock geologic map of the Williamstown and North Adams quadrangles, Massachusetts and Vermont, and part of the Cheshire quadrangle, Massachusetts: U.S. Geological Survey Miscellaneous Investigations Series Map, I-2369, 13 p., 2 sheets, scale 1:24,000. [http://pubs.er.usgs.gov/publication/i2369]
Geographic coverage	Bennington