Waterford Group - Rope Ferry Gneiss (RIZwr;0)

State	Rhode Island
Name	Waterford Group - Rope Ferry Gneiss
Geologic age	Late Proterozoic? or older?
Original map label	Zwr
Comments	Part of Hope Valley Subterrane Per printed map: age of rock based on radiometric data from RI012.
Primary rock type	mafic gneiss
Secondary rock type	granitic gneiss
Other rock types	amphibolite
Lithologic constituents	Major Metamorphic > GneissLight- to dark gray, fine- to medium-grained tonalite gneiss composed of plagioclase, quartz biotite, and hornblende, commonly interlayered with granite gneiss composed of microcline, plagioclase, quartz, biotite, and hornblende. Incidental Metamorphic > Amphibolite
Map references	Hermes, O.D., Gromet, L.P., Murray, D.P., Hamidzada, N.A., 1994, Geologic Map of Rhode Island, file name = bedrock_shp.zip (870kb) obtained from Rhode Island Geographic Information System, http://www.edc.uri.edu/rigis-spf/Statewide/state.html#geology , shapefile or interchange file, scale 1/100,000. [http://www.edc.uri.edu/rigis-spf/Statewide/state.html#geology]
Unit references	Hermes, O.D. (comp.), Gromet, L.P. (comp.), Murray, D.P. (comp.), Hamidzada, N.A., Skehan, J.W., and Mosher, S., 1994, Bedrock geologic map of Rhode Island: Rhode Island Map Series No. 1, Kingston, Rhode Island, scale 1: 100,000. Zartman, R.E., Hermes, O.D., and Pease, M.H., Jr., 1988, Zircon crystallization ages, and subsequent disturbance events, in Gneissic rocks of eastern Connecticut and western Rhode Island: American Journal of Science, v. 288, p. 376-402.
Geographic coverage	Washington