Rocks surrounding Granville dome in southeasternmost MA and northern CT were mapped by Schnabel (1974) and Knapp (1978) as The Straits Schist. These rocks correlate with Goshen Formation in MA. Goshen was chosen for this report and for the MA State bedrock geologic map (Zen and others, 1983) for continuity with Goshen farther north into MA. [It is unclear as to whether the name The Straits Schist is restricted from all of MA, or from just the area around Granville dome. Papers presented as chapters in U.S. Geological Survey Professional Paper 1366 are intended as explanations and (or) revisions to MA State bedrock geologic map of Zen and others (1983) at scale of 1:250,000.]

Source: GNU records (USGS DDS-6; Reston GNULEX).

Distinctive sequence of metamorphic strata overlying the Collinsville Formation in the Bristol quad., is here correlated with the Straits Schist of Fritts (1963) in the Southington quad. Consists mainly of rusty-weathering, medium- to coarse-grained, commonly crenulated, garnet-bearing, graphitic, muscovite-rich, plagioclase-quartz schist with graded bedding. Unit is called The Straits Schist following the original usage of Rodgers and others (1959). In the southern part of the Bristol quad., unit includes the Southington Mountain Member (here reduced in rank) in its upper part. Age of The Straits is inferred to be Silurian or Devonian. Unit is tentatively correlated with the Goshen Formation based on lithologic similarities and a possible unconformity at the base.

Source: GNU records (USGS DDS-6; Reston GNULEX).