Dry Hill Gneiss (MAZdh;0)

State	Massachusetts
Name	Dry Hill Gneiss
Geologic age	Proterozoic Z
Original map label	Zdh
Comments	Part of Bronson Hill Zone (Ordovician and Older Rocks) Microcline gneiss of the Dry Hill Gneiss in the Pelham dome, a metamorphosed alkali rhyolite, is confirmed to be Late Proterozoic with an age of 613+/-3 Ma (Tucker and Robinson, 1990) per MA015.
Primary rock type	granitic gneiss
Secondary rock type	quartzite
Other rock types
Lithologic constituents	Major Metamorphic > Gneisspink microcline-biotite and microcline-hornblende gneiss Minor Metamorphic > Metasedimentary > Metaclastic > Quartzitecontaining pink microcline megacrysts and minor quartzite
Map references	Unpublished Digital Geologic Map of Massachusetts received from Rudi Hon at Boston College in 1998.
Unit references	Zen, E-An (ed.), Goldsmith, R. (comp.), Ratcliffe, N.M. (comp.), Robinson, P. (comp.), Stanley, R.S. (comp.), Hatch, N.L., Jr., Shride, A.F., Weed, E.G.A., Wones, D.R., 1983, Bedrock Geologic Map of Massachusetts: U.S. Geological Survey, Reston, VA, scale 1: 250,000. Tucker, R.D. and Robinson, Peter, 1990, Age and setting of the Bronson Hill magmatic arc; a re-evaluation based on U-Pb zircon ages in southern New England: Geological Society of America Bulletin, v. 102, no. 10, p. 1404-1419.
Geographic coverage	Franklin - Hampshire