|Geologic age||Lower Devonian|
Metamorphic > Schistquartz schist grading upward into light- to dark-gray, carbonaceous aluminous schist in beds 5 to 15 cm thick
Metamorphic > Metasedimentary > Metaclastic > Quartzitemicaceous quartzite
|Comments||Part of Connecticut Valley Belt (Silurian and Devonian Rocks). Secondary unit description per MA006 as reported in USGS Geologic Names lexicon (ref. MA024): Underlies approximately the western half of that part of Connecticut Valley belt that lies west of Mesozoic basin. At VT State line, Goshen is exactly continuous with Northfield Formation of southern VT. The name Goshen, rather than Northfield, is chosen for these rocks in MA because it has been applied to at least some of them in MA since Emerson's (1898) reports and because the relatively massive and faintly bedded rocks of Northfield Formation in VT change character quite dramatically a few miles south of MA-VT border. Rocks surrounding Granville dome in southernmost MA and adjacent CT were previously mapped as The Straits Schist by Schnabel (1974) and Knapp (1978). Because the Goshen and The Straits are correlative, authors have chosen Goshen for continuity in CT. The unit of planar-bedded schist and minor interbedded brown-weathering carbonate rock mapped as Waits River Formation by Hatch and Hartshorn (1968) northeast of Shelburne Falls dome is here reassigned to Goshen Formation. Contact between Goshen and Waits River is defined as the line along which, going eastward, character of schists changes from aluminous, quartz-poor, and planar-bedded to alumina-poor, contorted, and rich in quartz veins. Although Goshen is subdivided into six informal members on the MA State bedrock geologic map (Zen and others, 1983), all are characterized by at least some gray, graphitic, generally nonrusty-weathering schist. Three members are widespread and are found in consistent stratigraphic sequence in a north-south belt across the State. The other three members are found locally around the vicinity of the Shelburne Falls, Woronoco, and Granville domes. Early Devonian age is based on stratigraphic position and relations to Waits River and Gile Mountain Formations, and on fossil-based Silurian age of underlying rocks (Hatch and others, 1988).|
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., and Wones, D.R., 1983, Bedrock Geologic Map of Massachusetts: U.S. Geological Survey, Reston, VA, scale 1: 250,000.
Hatch, N.L., Jr., Robinson, Peter and Stanley, R.S., 1988, Stratigraphy of the Connecticut Valley belt, Chapter B, IN Hatch, N.L., Jr., ed., Bedrock geology of Massachusetts: U.S. Geological Survey Professional Paper, 1366-A-D, p. B1-B34.
USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/Geolex/
|Counties||Franklin - Hampden - Hampshire|