Interbedded thick feldspathic wackes, tan and green slates, and minor calcareous lenses.
Thinly laminated, "pin-striped" gray, green, or tan metapelite and quartzite.
Perry Mountain Formation, Sedimentary and subordinate distal felsic and mafic volcanic facies in Piermont allochthon.
Pink, moderately to weakly foliated.
Rangeley Formation, undivided.
Found in northern New Hampshire.
Typically pink, coarse-grained mesoperthitic biotite (amphibole-free) granite; locally fine-grained or porphyritic.
Gray metapelite and metawacke and subordinate metavolcanic rocks; generally, but not everywhere, conformable with underlying Fitch or Madrid Formations. Fossiliferous in western New Hampshire.
Very rusty weathering, thinly bedded sulfidic-graphitic schist and pyrrhotitic calc-silicate granofels. Eastern facies equivalent to lower part of the Fitch Formation. Locally mapped as Francestown Formation of Nielson (1981) in southern New Hampshire.
Similar to Concord Granite.
Interbedded gray phyllite, in places containing feldspathic clasts, and feldspathic metasandstone, variably graded.
Ammonoosuc Volcanics, Metabasalt.
Frontenac Formation, Proximal bimodal volcanic facies.
Hornblende (or alkalic amphibole) syenite.
Metavolcanic and metasedimentary rocks of the lower part of Ammonoosuc Volcanics, undivided.
Trondhjemite and quartz diorite in northern Jefferson dome in Gorham quadrangle.
Hornblende-biotite quartz syenite to syenite.
Foliated biotite and (or) hornblende granite; locally diorite and lesser amounts of gabbro. Where present, potassium feldspar is microcline. Contact aureole is in the Albee Formation. U-Pb zircon ages of 442±4 Ma, no. 30 (Moench and Aleinikoff, 2003), and 444.1±2.1 Ma, no. 29 (Rankin and Tucker, 2009); and U-Pb sphene age of 443±3 Ma, no. 31 (Moench and Aleinikoff, 2003). Part of the Highlandcroft Plutonic Suite: Epizonal to mesozonal, foliated and metamorphosed (greenschist facies) plutons exposed northwest of the Ammonoosuc fault. Compositions range from granite to diorite to lesser amounts of gabbro. Part of the Bronson Hill arch intrusive rocks.
More mafic rocks have hornblende; part of Lost Nation pluton.
Frontenac Formation, Massive tan- or brown-weathering calcite-ankerite-muscovite granofels and interbedded gray metapelite - Probably partly a facies equivalent to the Waits River Formation in Vermont.
Formations unidentifiable owing to obliteration of original sedimentary or volcanic characteristics by anatexis or by numerous intrusions.
Ammonoosuc Volcanics, Bimodal volcanic rocks - Locally includes unmapped Oals.
Thick-bedded, ankeritic, micaceous, and feldspathic metasandstones interlayered with subordinate dark-gray metapelite. Metasandstone beds commonly are rusty weathering and up to 4 m thick; calc-silicate lenses locally present. Part of the Connecticut Valley Trough.
Rusty, dark metapelite containing thin coticule laminations, feldspathic metatuff, and vein quartz lenses.
Biotite quartz diorite in northeastern New Hampshire
Ironbound Mountain Formation, Felsic volcanic member.
Madrid and Smalls Falls Formations, undivided.
Smalls Falls Formation, Metabasalt member.
Found in Percy quadrangle of northern New Hampshire.
Porphyritic (alkalic feldspar) biotite granite.
Contains riebeckite and (or) hastingsite.
Light-gray to greenish-gray, white-weathering, fine-grained feldspathic metasandstone and metasiltstone, and light-gray to greenish-gray to dark-gray phyllite. Lesser amounts of quartzite. Rare calc-silicate nodules. Generally sharply bedded, but graded beds as well as slump structures are locally obvious. Tourmaline is a sporadic accessory mineral. May be sulfidic (either pyrite or pyrrhotite) and rusty weathering. “Pinstriping” is common. U-Pb zircon SHRIMP age of 492.5±7.8 Ma from a porphyritic tonalite sill about 2 km east of West Bath, N.H. (D.W. Rankin, USGS, unpub. data, 2011). Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt.
Massive to weakly foliated, purple biotite-feldspar granofels, layered calc-silicate, and dark pelitic-sulfidic schist containing calc-silicate pods in upper member; an eastern facies equivalent to the upper part of the Fitch Formation. Locally mapped as the Warner Formation of Nielson (1981) in southern New Hampshire.
Hornblende quartz monzonite.
Porphyritic biotite granodiorite in northern Jefferson dome in Milan quadrangle.
Foliated to nonfoliated and coarse- to fine-grained; includes mafic dikes tentatively correlated with Chickwolnepy intrusions.
Gray metapelite containing sparse siltstone laminations and abundant lenses of vein quartz.
Sharply interbedded quartzites, light-gray nongraphitic metapelite, and "fast-graded" meta-turbidites. Coticule layers common.
Northernmost New Hampshire.
Composition ranges from quartz monzonite to diorite.
Hornblende or alkalic amphibole quartz syenite.
Mount Osceola Granite, Granite containing hornblende and, locally, hastingsite, ferrohedenbergite, or fayalite.
Frontenac Formation, Mixed volcanic and sedimentary facies.
Quartz-pebble conglomerate overlain by rusty metapelite and feldspathic quartzite.
Granite containing phenocrysts of smoky quartz and microperthite; alkalic amphibole, hornblende, and hedenbergite or fayalite may be present. "Mount Lafayette" type granite porphyry of Billings (1955).
Part of Lost Nation pluton of northwestern New Hampshire.
Gray to tan metawacke and schist or phyllite; gradational into Meetinghouse Slate Member but more thickly bedded and less pelitic than the member. Includes minor metavolcanic lentils.
Contains minor muscovite. Makes up Cambridge Black pluton.
Ammonoosuc Volcanics, Volcaniclastic metagraywackes.
Found in Woodsville and Whitefield quadrangles and in small intrusive units in northern and southeastern New Hampshire.
Thickly bedded feldspathic volcaniclastic grit and interbedded gray slate. Equivalent to Grenier Ponds Member of the Ironbound Mountain Formation in western Maine.
Found in northwestern New Hampshire.
Rusty-weathered, dark siliceous scaly slate or schist of flaser structure, polymictic fragments from a few mm to (in Maine) several hundred meters. A melange consisting of metasedimentary, felsic/mafic metavolcanics, and ultramafic rocks..
Frontenac Formation, Graded-bedded metagraywacke and subordinate gray phyllite.
Porphyritic phase of hornblende-biotite tonalite.
Porphyritic biotite quartz syenite in central Jefferson dome in Mt. Washington quadrangle.
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.
Chiefly in northern New Hampshire.
Leucocratic granite to quartz syenite.
Light- to medium-gray, fine-grained micaceous metasandstones that grade upward into subordinate dark-gray slate or phyllite; some rocks are calcareous. Graded sets range in thickness from a few centimeters to about a meter; typically they are 10 to 30 cm thick. Contact with Di gradational. Part of the Connecticut Valley Trough.
(Kinsman Quartz Monzonite of Billings, 1955) - Foliated granite, granodiorite, tonalite, and minor quartz diorite; large megacrysts of potassium feldspar characteristic; garnet locally abundant.
Medium-dark-gray to grayish-black lustrous slate, phyllite, and schist containing sparse to moderately abundant 1-mm to- 5-cm-thick beds of light-gray, fine-grained metasandstone and metasiltstone, commonly pyritiferous and calcareous. Some graded beds. Gradational contact with Dco above and Dir below. Interpreted to be correlative with the Meetinghouse Slate Member of the Gile Mountain Formation. Part of the Connecticut Valley Trough.
Dark-gray slate interlayered with thin beds of light-gray, fine-grained micaceous and feldspathic metasandstone (typically ribby weathering). Abruptly graded beds <1 cm to 30 cm thick are locally common as is channeling and, in places, soft-sediment deformation. Commonly sulfidic and rusty weathering. Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt.
Leucocratic, pink or light-brown, and mesoperthitic.
Smalls Falls Formation, Mixed metavolcanic rocks and metavolcanic sediments.
Ammonoosuc Volcanics, Metasedimentary rocks.
Smalls Falls Formation, Felsic metavolcanic member.
Two-mica granite of the Sebago batholith and Effingham pluton of eastern New Hampshire.
Perry Mountain and Rangeley Formations, undivided.
Ironbound Mountain Formation, Euxinic metashale member.
Metamorphosed aphyric rhyolite tuff. Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt.
Gray to light-gray, fine-grained micaceous quartzite a few centimeters to tens of centimeters thick, interbedded with dark-gray graphitic slate, phyllite, or schist. Part of the Connecticut Valley Trough.
Pillow metabasalt member. Lenses within the Hurricane Mountain Formation of northern New Hampshire interpreted as tectonic rafts of Jim Pond Formation.
Ironbound Mountain Formation, Basaltic to andesitic member.
Commonly contains alkalic amphibole and mesoperthite.
Almost-white to dark-gray, locally pink, medium- to coarse-grained hypidiomorphic, granular, biotite-muscovite-microcline-plagioclase granite; accessories include apatite, sphene, pyrite, and magnetite. Igneous rocks of the Northeast Kingdom batholith of Ayuso and Arth (1992). Part of the New Hampshire Plutonic Suite.
Smalls Falls Formation, Metaconglomerate member - Found in Errol quadrangle in northern New Hampshire.
Perry Mountain Formation, Volcanic facies in Piermont allochthon.
Ordovician - Cambrian Dead River formation lower member
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.
Mount Osceola Granite, Green biotite mesoperthitic granite.
Ironbound Mountain Formation, Metarhyolite and microgranite intrusions.
Has varying amounts of olivine, augite, and hornblende.
Ammonoosuc Volcanics, White quartz-kyanite rock and silicate iron-formation.
Dark-greenish-gray to medium-bluish-gray metamorphosed andesitic and basaltic tuff, crystal tuff, and tuff breccia; minor pillow lava. Commonly contains plagioclase and (or) altered mafic phenocrysts. Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt. Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt.
Greenish-gray to pink hornblende-biotite quartz syenite. Monadnock Mountain pluton: Composite stock of quartz syenite, syenite granite, and essexite. K-Ar age of 175±4 Ma (Foland and Faul, 1977). Part of the White Mountain Igneous Suite.
Greenish-gray, light-bluish-gray, or medium-bluish-gray metarhyolite tuff, lapilli tuff, tuff breccia, and lava. Generally porphyritic with 5 to 20 percent plagioclase and, in some places, quartz phenocrysts. Generally strongly foliated with waxy sheen on foliation surfaces. Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt.
Ordovician - Cambrian unnamed volcanic rocks
Devonian Ironbound Mountain Formation
Locally fossiliferous in Whitefield quadrangle.
Cambrian Hurricane Mountain Formation
Ordovician - Cambrian Aziscohos Formation
Silurian - Ordovician Frontenac Formation
Ordovician unnamed volcanic and sedimentary rocks
Cambrian Jim Pond Formation graywacke
Medium-light-bluish-gray, medium-bluish-gray, medium-dark-gray, to medium-dark-greenish-gray metasiltstone and phyllite, and medium-gray feldspathic metawacke. Purple tinge common; coticule and magnetite locally abundant. Stratified rocks of the Bronson Hill arch and Sawyer Mountain belt.
Ordovician gabbro/diorite/ultramafic rocks
Devonian pyroxene-hornblende quartz monzodiorite and quartz diorite - pyroxene-hornblende-biotite quartz monzodiorite, and pyroxene-hornblende-biotite quartz diorite
Ordovician - Cambrian Dead River formation