Geologic Unit: North River
Publication: Ratcliffe, N.M., and Armstrong, T.R., 1999, Bedrock geologic map of the West Dover and Jacksonville quadrangles, Windham County, Vermont: U.S. Geological Survey Miscellaneous Investigations Series Map, I-2552, 30 p., 2 sheets, scale 1:24,000 [Available online from the USGS PubsWarehouse: http://pubs.er.usgs.gov/pubs/i/i2552]Usage in Publication:
North River Igneous Suite*
Named the North River Igneous Suite for igneous rocks that intrude the Cram Hill Formation in VT. Unit consists of a massive gneiss unit (white to light-gray, well foliated to blastomylonitic, poorly layered, garnet-biotite-muscovite-chlorite-quartz-plagioclase granofels), quartz-feldspar granofels member (light-brown to tan, chlorite-ilmenite-muscovite-quartz-plagioclase granofels), the Blue Mountain facies (dark-gray to black, poorly layered, porphyritic and nonporphyritic, ilmenite-epidote-chlorite-plagioclase-hornblende amphibolite), the Whitneyville facies (light- to medium-green, massive, epidote-ilmenite-sphene-chlorite-hornblende-plagioclase amphibolite), and the West Halifax Trondhjemite (light- to dark-gray, coarse-grained, massive, ilmenite-chlorite-epidote-muscovite-quartz-plagioclase trondhjemite). The Blue Mountain and Whitneyville facies comprise a dike and sill complex. Rocks of the North River Igneous Suite are younger than the Cram Hill Formation and older than the Northfield Formation. The North River is of Ordovician and Silurian(?) age.
Source: GNU records (USGS DDS-6; Reston GNULEX).