Rusty-weathering, pelitic schist, metasandstone, and local coarse-grained metasandstone lentils; calc-silicate pods common; minor coticule. Probably equivalent to member C of Rangeley Formation of Maine.
Granite, granodiorite, and tonalite.
(Kinsman Quartz Monzonite of Billings, 1955) - Foliated granite, granodiorite, tonalite, and minor quartz diorite; large megacrysts of potassium feldspar characteristic; garnet locally abundant.
Gray, thinly laminated (5-25 mm) metapelite with local lentils of turbidites and thin quartz conglomerates in western New Hampshire. Sparse calc-silicate pods and coticule. Probably equivalent to member B of Rangeley Formation of Maine.
Gray two-mica granite, locally grading to tonalite.
Black, rusty-weathering sulfidic-graphitic slate or schist and sparse to abundant metagraywacke. Lies stratigraphically between upper and lower parts of the Ammonoosuc Volcanics.
(Spaulding Quartz Diorite of Fowler-Billings, 1949) - Weakly foliated to nonfoliated, spotted biotite quartz diorite, tonalite, granodiorite, and granite; garnet and muscovite may or may not be present.
Ammonoosuc Volcanics, Bimodal volcanic rocks - Locally includes unmapped Oals.
Granodioritic to quartz dioritic gneissic border phase of Oobg, perhaps in part metasomatic. Part of the Bronson Hill arch intrusive rocks.
Gray metapelite and metawacke and subordinate metavolcanic rocks; generally, but not everywhere, conformable with underlying Fitch or Madrid Formations. Fossiliferous in western New Hampshire.
Dark-gray to coaly-black, fine-grained plagioclase-muscovite-quartz schist and metawacke, shown southeast of Springfield; in part correlative with staurolite-grade rocks mapped as Littleton Formation (Dl) flanking the Vernon dome (shown as DSwb/Dl). Part of the Connecticut Valley Trough.
Dark-gray to grayish-black, rusty-weathering sulfidic slate and phyllite interlayered with felsic volcanic rocks and tuffs, and amphibolite (Opa). Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt.
Thinly or poorly bedded aluminous lower part, somewhat rusty. Rare quartzite lentils. Carrabassett Formation in northwestern Maine is probably correlative.
Pink, moderately to weakly foliated.
Light-gray metaturbidite, lithologically identical to, and probably correlative with, the Seboomook Formation of Maine. Coticule layers common.
Medium- to coarse-grained, potassium-feldspar-megacrystic, biotite granodiorite gneiss of the Ashuelot pluton. U-Pb zircon age of 403±2 Ma (R.D. Tucker, USGS, written commun., 2008). Part of the Bronson Hill arch intrusive rocks.
(Bethlehem Gneiss of Billings, 1955) - Gray, strongly foliated biotite-muscovite granodiorite and associated tonalite and granite.
A heterogeneous unit of interlayered and interfingering metamorphosed volcanic, volcaniclastic, and sedimentary rocks. Compositions range from basalt to sodic rhyolite. Fragmental rocks dominate (tuff to tuff breccia), but include sparse mafic pillow lava and felsic lava. Sedimentary protoliths include dark-gray sulfidic shale, ironstone, siltstone, graywacke, volcanic conglomerate, and rare limestone. Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt.
Madrid and Smalls Falls Formations, undivided.
Granite, granodiorite, and trondhjemite.
Medium-dark- to dark-gray slate interlayered with light-gray, fine-grained micaceous quartzite; in southeastern Vermont near the Vernon dome Dl is equated with DSwb and may be older than in the Bradford area. Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt.
Interlayered, commonly rusty-weathering quartz-feldspar micaceous granofels and dark-gray mica schist containing porphyroblasts of garnet, staurolite, and kyanite. Calc-silicate lenses common in the granofels; granule and pebble metaconglomerate locally are present. Part of Piermont and other allochthons.
Fitch and Clough Formations, undivided.
Perry Mountain and Rangeley Formations, undivided.
Quartz-pebble conglomerate overlain by rusty metapelite and feldspathic quartzite.
Orthoquartzite, quartz metaconglomerate, muscovite schist, minor polymictic metaconglomerate. Disconformable below Fitch Formation and unconformable on Ordovician formations. Equivalent, in part, to member C of Rangeley Formation of Maine. Fossiliferous.
Medium- to coarse-grained, equigranular to porphyritic, muscovite-biotite-microcline-plagioclase metaquartz monzonite; contains garnet, sillimanite-andalusite and cordierite; intrudes rocks of the Rangeley Formation in New Hampshire. U-Pb zircon age of 407±5 Ma, no. 43 (Kohn and others, 1992) at Bellows Falls. Part of the Bronson Hill arch intrusive rocks.
Metamorphosed limestone, calcareous sandstone, siltstone, and pelite. Some limestone conglomerate and polymict conglomerate with calcareous matrix. Locally equivalent to Madrid and Smalls Falls Formations in Chesterfield, N.H., area. Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt.
Quartzite and quartz-cobble metaconglomerate. Locally contains quartz-cobble conglomerate with abundant dark-gray phyllite matrix that resembles phyllite of the Littleton Formation. Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt.
Thinly bedded. Close to transition from lower to upper parts of the Rangeley Formation. Probably equivalent to part of Paxton Formation of Zen and others (1983) in Massachusetts.
Within unit Sr; rusty sulfidic schist occurs in Fall Mountain nappe near Bellows Falls. Part of Piermont and other allochthons.
Predominantly dark- to light-gray, lustrous, carbonaceous chlorite-biotite-muscovite-quartz slate, phyllite, or schist; contains thin beds of quartzite and only sparse layers of punky-weathering limestone. Shown south of the Pomfret dome where rocks typical of the Gile Mountain Formation are absent, and near Randolph. Part of the Connecticut Valley Trough.
Metamorphosed limestone, calcareous sandstone, siltstone, and dark pelitic schist; lower contact is disconformable on the Clough Quartzite. Fossiliferous.
Contains biotite and hornblende.
Amphibolite. Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt.
Light-gray to white, garnet-muscovite-biotite granodiorite at Gassetts quarry, having a U-Pb zircon SHRIMP age of 392±6 Ma, no. 46 (Aleinikoff and others, 2011), from rims on Proterozoic-age cores (J.N. Aleinikoff, USGS, written commun., 2002); and whitish-gray muscovite-rich quartz monzonite and granodiorite, granite pegmatite, and aplite which occur as crosscutting nonfoliated dikes within the core of the domes and as folded and well-foliated dikes on the east and west flanks of the domes; also granite dikes and small stocks of very light gray to white, muscovite-rich, locally garnet-bearing, fine- to medium-grained biotite-muscovite quartz monzonite and granodiorite, locally orbicular, that intrude cover rocks east of the Green Mountain massif from Jamaica to Northfield, including the Liberty Hill locality and the granodiorite stock east of Plymouth. The latter contains inherited zircon with rims having an imprecise SHRIMP age of about 380 to 390 Ma (Aleinikoff and others, 2011); a similar dike south of Plymouth has a U-Pb zircon SHRIMP age of 365±5 Ma, no. 49 (Aleinikoff and others, 2011). These closely resemble undated white granodiorites of the Bethel area and dikes in the Chester and Athens domes; also resemble small dikes of granite, trondhjemite, and quartz monzonite largely west of the Connecti-cut Valley trough. Devonian granitic rocks of southern Vermont. Part of the New Hampshire Plutonic Suite.
Silvery-grayish-green to light-gray, muscovite-biotite (chlorite)-plagioclase-quartz schist and granofels. Part of the Connecticut Valley Trough.
Spatially associated with Spaulding Tonalite plutons.
Sharply interbedded quartzites, light-gray nongraphitic metapelite, and "fast-graded" meta-turbidites. Coticule layers common.
Within unit Sr; quartz conglomerate occurs in Fall Mountain nappe near Bellows Falls. Part of Piermont and other allochthons.