|Geologic age||Lower Devonian|
Metamorphic > Gneiss > Biotite-gneissOrthopyroxene-biotite gneiss, probably originally intermediate volcanic rocks.
|Comments||Part of Merrimack Belt (Silurian, Devonian and Pennsylvanian Rocks). Secondary unit description per MA006 as reported in USGS Geologic Names lexicon (ref. MA024): Report text and figures deal extensively with areal extent of Littleton in MA, but footnotes [added to the report just before the report went to press] indicate two major restrictions to the use of the Littleton [these changes are not reflected on the MA State bedrock geologic map]: 1) Recent stratigraphic interpretations in the Monadnock (Thompson, 1985) and Hinsdale (Elbert, 1986) areas, NH, and remapping in the Mt. Grace area (Robinson, 1987), MA, have shown that garnet quartzite and iron formation mapped as Littleton Formation in the Pelham-Shutesbury syncline in MA, are now assigned to the Perry Mountain Formation, [here geographically extended to MA.] 2) Littleton Formation rocks in the belt that enters MA from NH east of the Keene gneiss dome and extending to southwest of Ware, and rocks in the Amherst inlet where Littleton and Partridge are complexly interfolded, are here assigned to the Rangeley Formation [here geographically extended to MA]. [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.] (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/