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Mineral Resources > Online Spatial Data > Geology > by state > New Hampshire Geology

Geologic units in Grafton county, New Hampshire

Hornblende granodiorite (Late Ordovician) at surface, covers 0.1 % of this area

Hornblende granodiorite.

Lithology: granodiorite

Ammonoosuc Volcanics, Bimodal volcanic rocks (Middle - Upper Ordovician) at surface, covers 0.9 % of this area

Ammonoosuc Volcanics, Bimodal volcanic rocks.

Lithology: bimodal suite

Hornblende granodiorite of Highlandcroft pluton (Late Ordovician) at surface, covers 0.1 % of this area

Hornblende granodiorite of Highlandcroft pluton - Contains minor tonalite and diorite.

Lithology: granodiorite; tonalite; diorite

Hornblende gabbro (Late Ordovician) at surface, covers < 0.1 % of this area

Hornblende gabbro.

Lithology: gabbro

Gile Mountain Formation, undivided (Lower Devonian) at surface, covers < 0.1 % of this area

Gile Mountain Formation, undivided - 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.

Lithology: schist; metasedimentary rock; phyllite; slate; metavolcanic rock

Concord Granite (Late Devonian ) at surface, covers 4 % of this area

Concord Granite - Gray two-mica granite, locally grading to tonalite.

Lithology: granite; tonalite

Littleton Formation, Volcanic lentils (Lower Devonian) at surface, covers 0.4 % of this area

Littleton Formation, Volcanic lentils - Both mafic and felsic

Lithology: mafic metavolcanic rock; felsic metavolcanic rock

Kinsman Granodiorite (Early Devonian ) at surface, covers 13 % of this area

Kinsman Granodiorite - (Kinsman Quartz Monzonite of Billings, 1955) - Foliated granite, granodiorite, tonalite, and minor quartz diorite; large megacrysts of potassium feldspar characteristic; garnet locally abundant.

Lithology: granite; granodiorite; tonalite; quartz diorite

Augite-hornblende-biotite gabbro (Cretaceous) at surface, covers < 0.1 % of this area

Augite-hornblende-biotite gabbro - Fine- to coarse-grained.

Lithology: gabbro

Porphyritic biotite granodiorite (Early - Late Devonian) at surface, covers < 0.1 % of this area

Porphyritic biotite granodiorite - Found in Mt. Cube quadrangle.

Lithology: granodiorite

Orfordville Formation (Ordovician) at surface, covers < 0.1 % of this area

Orfordville Formation - Carbonaceous phyllite; minor quartzite.

Lithology: phyllite; quartzite

Fitch Formation (Upper Silurian; Pridolian and Ludlovian) (Upper Silurian - (Pridolian and Ludlovian)) at surface, covers 0.4 % of this area

Fitch Formation - Metamorphosed limestone, calcareous sandstone, siltstone, and dark pelitic schist; lower contact is disconformable on the Clough Quartzite. Fossiliferous.

Lithology: marble; quartzite; phyllite; pelitic schist

Littleton Formation, Metabasaltic greenstone or amphibolite (Lower Devonian) at surface, covers < 0.1 % of this area

Littleton Formation, Metabasaltic greenstone or amphibolite.

Lithology: greenstone; amphibolite

Perry Mountain Formation, Sedimentary and subordinate distal felsic and mafic volcanic facies in Piermont allochthon (Lower?- Middle? Silurian) at surface, covers 3 % of this area

Perry Mountain Formation, Sedimentary and subordinate distal felsic and mafic volcanic facies in Piermont allochthon.

Lithology: metasedimentary rock; felsic metavolcanic rock; mafic metavolcanic rock

Winnipesaukee Tonalite (Early Devonian) at surface, covers 0.7 % of this area

Winnipesaukee Tonalite (Winnipesaukee Quartz Diorite of Billings, 1955) - Gray, massive to foliated tonalite and minor quartz diorite, granodiorite, and granite. Probably coeval with Spaulding Tonalite.

Lithology: tonalite; quartz diorite; granodiorite; granite

Albee Formation (Ordovician) at surface, covers 0.1 % of this area

Albee Formation - Massive, gray, white-weathered quartzite and feldspathic quartzite interbedded with greenish-gray slate, phyllite, feldspthic phyllite and quartzose argillaceous phyllite. Micaceous quartzite, quartz-mica schist, mica schist and hornfels contining porphyroblasts of biotite, garnet, staurolite and sillimanite in the vicinity of granitic plutons. Soda-rhyolite tuff occurs locally. Micaceous quartzite characterized by thin, schistose "pinstripe" partings is common in many areas.

Lithology: quartzite; slate; phyllite; mica schist; hornfels; tuff

Porphyritic syenite (Jurassic) at surface, covers 0.2 % of this area

Porphyritic syenite - Hastingsite or hornblende and (or) hedenbergite are present.

Lithology: syenite

Spaulding Tonalite (Early Devonian) at surface, covers 0.4 % of this area

Spaulding Tonalite (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.

Lithology: quartz diorite; tonalite; granodiorite; granite

Granodiorite to tonalite (Late Ordovician) at surface, covers 4 % of this area

Granodiorite to tonalite.

Lithology: granodiorite; tonalite

Gile Mountain Formation (Devonian) at surface, covers < 0.1 % of this area

Gile Mountain Formation - Gray quartz-muscovite phyllite or schist, interbedded and intergradational with gray micaceous quartzite (graywacke northeast of Nulhegan River), calcareous mica schist, and, locally, quartzose and micaceous crystalline limestone like that of the Waits River formation. The phyllite and schist commonly contain porphyroblasts of biotite, garnet, or staurolite, and locally kyanite, andalusite, or sillimanite. Used as Early Devonian Gile Mountain Formation. Generally consists of gray to tan metawacke and schist or phyllite, gradational into its Meetinghouse Slate Member, but much more thickly bedded and less pelitic. Contains minor metavolcanic lentils. Unnamed metavolcanic member is possibly equivalent to Putney Volcanics of southeastern VT. Separately mapped interbedded gray slate or phyllite and brown-weathering calcite-ankerite metasiltstone, and minor marble and quartzite, resembles Waits River Formation of VT. Meetinghouse Slate Member consists of gray to black phyllite and silty metasandstone turbidite. Report includes geologic map, cross sections, correlation chart, and four 1:500,000-scale derivative maps (Lyons and others, 1997).

Lithology: phyllite; mica schist; quartzite; limestone; graywacke

Metamorphosed gabbro, diorite, and intrusive basalt dikes (Devonian? - Silurian?) at surface, covers 0.1 % of this area

Metamorphosed gabbro, diorite, and intrusive basalt dikes - Chiefly in northern New Hampshire.

Lithology: metavolcanic rock

Ammonoosuc Volcanics, Metasedimentary rocks (Middle - Upper Ordovician) at surface, covers 0.2 % of this area

Ammonoosuc Volcanics, Metasedimentary rocks - Contains mafic metavolcanic lenses.

Lithology: metasedimentary rock; mafic metavolcanic rock

Partridge Formation, Interstratified metavolcanic rocks (Middle - Upper Ordovician) at surface, covers 0.3 % of this area

Partridge Formation, Interstratified metavolcanic rocks - Chiefly amphibolites, found in southwestern New Hampshire.

Lithology: amphibolite; metavolcanic rock

Madrid Formation (Upper Silurian? ) at surface, covers 0.7 % of this area

Madrid Formation - 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.

Lithology: granofels; calc-silicate schist; pelitic schist

Hornblende (or alkalic amphibole) syenite (Jurassic) at surface, covers 0.1 % of this area

Hornblende (or alkalic amphibole) syenite.

Lithology: syenite

Metavolcanic and metasedimentary rocks of the lower part of Ammonoosuc Volcanics, undivided (Middle Ordovician) at surface, covers < 0.1 % of this area

Metavolcanic and metasedimentary rocks of the lower part of Ammonoosuc Volcanics, undivided.

Lithology: metavolcanic rock; metasedimentary rock

Littleton Formation, Lower unnamed member (Lower Devonian) at surface, covers 5 % of this area

Littleton Formation, Lower unnamed member - Thinly or poorly bedded aluminous lower part, somewhat rusty. Rare quartzite lentils. Carrabassett Formation in northwestern Maine is probably correlative.

Lithology: metasedimentary rock; metavolcanic rock; quartzite

Ammonoosuc Volcanics (Ordovician) at surface, covers < 0.1 % of this area

Ammonoosuc Volcanics - Fine-grained chloritic and biotitic gneiss and greenstone in areas north of Bellows Falls; biotite gneiss and amphibolite south of Bellows Falls. (Southeastern Vermont).

Lithology: biotite gneiss; greenstone; amphibolite

Migmatitic rocks (Devonian - Silurian) at surface, covers 0.3 % of this area

Migmatitic rocks - Formations unidentifiable owing to obliteration of original sedimentary or volcanic characteristics by anatexis or by numerous intrusions.

Lithology: migmatite

Quimby Formation (Upper Ordovician?) at surface, covers < 0.1 % of this area

Quimby Formation - Black graphitic-sulfidic rusty-weathering schist and thickly bedded metagraywacke.

Lithology: schist; metasedimentary rock

Pink equigranular biotite granite (Late Devonian) at surface, covers 1 % of this area

Pink equigranular biotite granite - Found in Woodsville and Whitefield quadrangles and in small intrusive units in northern and southeastern New Hampshire.

Lithology: granite

Upper part of Rangeley Formation (Lower Silurian (Llandoverian)) at surface, covers 3 % of this area

Upper part of Rangeley Formation - 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.

Lithology: pelitic schist; metasedimentary rock; calc-silicate rock

Undifferentiated Granitic Rocks (Ordovician) at surface, covers < 0.1 % of this area

Undifferentiated granitic rocks.

Lithology: granite

Mount Osceola Granite, Granite containing hornblende and, locally, hastingsite, ferrohedenbergite, or fayalite (Early - Middle Jurassic) at surface, covers 3 % of this area

Mount Osceola Granite, Granite containing hornblende and, locally, hastingsite, ferrohedenbergite, or fayalite.

Lithology: granite

Littleton Formation, Calc-silicate rock (Lower Devonian) at surface, covers < 0.1 % of this area

Littleton Formation, Calc-silicate rock - Possibly equivalent in part to Hildreths Formation of Maine but not restricted to one horizon. Locally fossiliferous, as in Moosilauke quadrangle.

Lithology: calc-silicate rock

Perry Mountain Formation, undivided (Lower? - Middle? Silurian) at surface, covers 2 % of this area

Perry Mountain Formation, undivided - Sharply interbedded quartzites, light-gray nongraphitic metapelite, and "fast-graded" meta-turbidites. Coticule layers common.

Lithology: quartzite; meta-argillite; metasedimentary rock

Conway Granite (Middle - Late? Jurassic) at surface, covers 8 % of this area

Conway Granite - Typically pink, coarse-grained mesoperthitic biotite (amphibole-free) granite; locally fine-grained or porphyritic.

Lithology: granite

Metadiorite (Devonian) at surface, covers < 0.1 % of this area

Metadiorite - Dikes and sills of metagabbro, metadiabase and meta-andesite too small to show are chiefly in the Missisquoi, Albee, and Orfodville formations.

Lithology: metavolcanic rock

Ammonoosuc Volcanics, Volcaniclastic metagraywackes (Middle - Upper Ordovician) at surface, covers < 0.1 % of this area

Ammonoosuc Volcanics, Volcaniclastic metagraywackes.

Lithology: metasedimentary rock

Granite porphyry (Early Jurassic) at surface, covers 2 % of this area

Granite porphyry - 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).

Lithology: granite

Porphyritic (alkalic feldspar) biotite granite (Late Ordovician) at surface, covers 0.3 % of this area

Porphyritic (alkalic feldspar) biotite granite.

Lithology: granite

Clough Quartzite (Lower Silurian (upper Llandoverian)) at surface, covers 0.7 % of this area

Clough 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.

Lithology: quartzite; meta-conglomerate; mica schist

Gile Mountain Formation, Meetinghouse Slate Member (Lower Devonian ) at surface, covers < 0.1 % of this area

Meetinghouse Slate Member - Gray to black phyllite and silty metasandstone turbidite.

Lithology: phyllite; metasedimentary rock

Gray augite-hornblende-biotite monzonite (Cretaceous) at surface, covers 0.1 % of this area

Gray augite-hornblende-biotite monzonite.

Lithology: monzonite

Madrid and Smalls Falls Formations, undivided (Silurian) at surface, covers 0.2 % of this area

Madrid and Smalls Falls Formations, undivided.

Lithology: granofels; schist; calc-silicate schist; pelitic schist

Biotite trondhjemite in Rumney quadrangle (Early - Late Devonian) at surface, covers 0.2 % of this area

Biotite trondhjemite in Rumney quadrangle.

Lithology: trondhjemite

Fitch and Clough Formations, undivided (Silurian) at surface, covers 0.9 % of this area

Fitch and Clough Formations, undivided.

Lithology: quartzite; marble; meta-conglomerate; sandstone; mica schist; siltstone; pelitic schist; marble

Partridge Formation, undivided (Middle - Upper Ordovician) at surface, covers 3 % of this area

Partridge Formation, undivided - Black, rusty-weathering sulfidic-graphitic slate or schist and sparse to abundant metagraywacke. Lies stratigraphically between upper and lower parts of the Ammonoosuc Volcanics.

Lithology: slate; schist; metasedimentary rock

Perry Mountain Formation, Volcanic facies in Piermont allochthon (Lower? - Middle? Silurian) at surface, covers 0.2 % of this area

Perry Mountain Formation, Volcanic facies in Piermont allochthon.

Lithology: felsic volcanic rock; mafic volcanic rock

Ammonoosuc Volcanics, Metasedimentary rocks (Middle - Upper Ordovician) at surface, covers 0.3 % of this area

Ammonoosuc Volcanics, Metasedimentary rocks.

Lithology: metasedimentary rock

Orfordville Formation, Post Pond Volcanics (Ordovician) at surface, covers < 0.1 % of this area

Orfordville Formation, Post Pond Volcanics - Greenstone, green chloritic schist interbedded with schistose felsite, quartz-feldspar-sericite schist; fine-grained chloritic, biotitic gneiss, all west of Ammonoosuc fault; mainly amphibolite east of the Ammonoosuc fault.

Lithology: greenstone; greenschist; mica schist; biotite gneiss; amphibolite

Greenvale Cove Formation (Lower Silurian? ) at surface, covers 0.2 % of this area

Greenvale Cove Formation - Grayish-violet interlaminated metashale, feldspathic metasandstone, and calc-silicate rock of the Piermont allochthon in western New Hampshire.

Lithology: meta-argillite; metasedimentary rock; calc-silicate rock

Littleton Formation, Metaconglomerate and quartzite (Lower Devonian) at surface, covers < 0.1 % of this area

Littleton Formation, Metaconglomerate and quartzite - Locally fossiliferous in Whitefield quadrangle.

Lithology: meta-conglomerate; quartzite

Lower part of Rangeley Formation (Lower Silurian (Llandoverian)) at surface, covers 2 % of this area

Lower part of Rangeley Formation - 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.

Lithology: meta-argillite; meta-conglomerate; calc-silicate rock

Hornblende or alkalic amphibole quartz syenite (Jurassic) at surface, covers < 0.1 % of this area

Hornblende or alkalic amphibole quartz syenite.

Lithology: quartz syenite

Tonalite (Middle Ordovician) at surface, covers < 0.1 % of this area

Tonalite - Extended from Joslin Turn, Vermont.

Lithology: tonalite

Smalls Falls Formation, undivided (Upper to Middle Silurian (Ludlovian and Wenlockian)) at surface, covers 1 % of this area

Smalls Falls Formation, undivided -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.

Lithology: schist; granofels

Rangeley Formation, undivided (Lower Silurian (Llandoverian)) at surface, covers 2 % of this area

Rangeley Formation, undivided.

Lithology: metasedimentary rock; calc-silicate rock; meta-argillite; quartzite; pelitic schist; granofels; felsic metavolcanic rock

Littleton Formation, undivided (Lower Devonian; Siegenian) at surface, covers 4 % of this area

Littleton Formation undivided - Gray metapelite and metawacke and subordinate metavolcanic rocks; generally, but not everywhere, conformable with underlying Fitch or Madrid Formations. Fossiliferous in western New Hampshire.

Lithology: metasedimentary rock; metavolcanic rock

Bethlehem Granodiorite (Early Devonian) at surface, covers 10 % of this area

Bethlehem Granodiorite (Bethlehem Gneiss of Billings, 1955) - Gray, strongly foliated biotite-muscovite granodiorite and associated tonalite and granite.

Lithology: granodiorite; tonalite; granite

Littleton Formation, Upper unnamed member (Lower Devonian) at surface, covers 4 % of this area

Littleton Formation, Upper unnamed member - Light-gray metaturbidite, lithologically identical to, and probably correlative with, the Seboomook Formation of Maine. Coticule layers common.

Lithology: metasedimentary rock

Ammonoosuc Volcanics, Metabasalt (Middle - Upper Ordovician) at surface, covers 0.8 % of this area

Ammonoosuc Volcanics, Metabasalt.

Lithology: meta-basalt

Gile Mountain Formation, Meetinghouse Slate Member (Devonian) at surface, covers < 0.1 % of this area

Gile Mountain Formation, Meetinghouse Slate Member - Chiefly gray slate or phyllite characterized by beds of gray schistose quartzite 1/8 inch to 3 inches thick. Gile Mountain Formation and its Meetinghouse Slate Member were previously considered to be Early Devonian based on Emsian plant fossils from Compton Formation of QUE (Hueber and others, 1990; Hatch, 1991). Age assignment here changed to Early Devonian(?) because recent mapping indicates that Gile Mountain and Compton are not coextensive across VT-QUE border as formerly believed by Doll and others (1961, State map) and St. Julien and Slivitsky (1987). Instead, the formations are separated by Ironbound Mountain Formation. Ironbound Mountain Formation is conformably overlain by Compton, but it is not yet known whether Ironbound Mountain is overlain or underlain by Gile Mountain; this is shown by queried Ironbound Mountain-Gile Mountain contact in area of Averill 7.5-min quad, VT. Correlation of Gile Mountain and Compton is justified only if Gile Mountain in this area conclusively is shown to be underlain by Ironbound Mountain; otherwise, Gile Mountain (with possible exception of its Meetinghouse Slate Member) would be coeval with Silurian Frontenac Formation. Hatch (1988) proposed that Meetinghouse represents upper part of Gile Mountain on basis of graded bedding seen south of map area. This relationship is not proven, however, because Gile Mountain-Meetinghouse contact is difficult to define and graded beds are not always easily interpreted. On this map, Meetinghouse is tentatively shown to occur below main body of Gile Mountain on basis of remarkable similarity between it and Ironbound Mountain Formation. This relationship easily explains highly pelitic character of the Meetinghouse with upward-coarsening character of Lower Devonian sequences elsewhere in map area. Meetinghouse Slate Member includes volcanic facies (Moench and others, 1995).

Lithology: slate; phyllite; quartzite

Large mesoperthitic phenocrysts in a pink to gray quartz syenite porphyry of "Albany type" (Cretaceous) at surface, covers < 0.1 % of this area

Large mesoperthitic phenocrysts in a pink to gray quartz syenite porphyry of "Albany type" - Alkalic amphibole or fayalite may be present. Part of Ossipee Mountain Complex of Kingsley (1931).

Lithology: quartz syenite

Ammonoosuc Volcanics, Bimodal volcanic rocks (Middle - Upper Ordovician) at surface, covers 8 % of this area

Ammonoosuc Volcanics, Bimodal volcanic rocks - Locally includes unmapped Oals.

Lithology: bimodal suite

Mesoperthitic granite (Jurassic) at surface, covers < 0.1 % of this area

Mesoperthitic granite - Contains riebeckite and (or) hastingsite.

Lithology: granite

Biotite tonalite (Early - Late Devonian) at surface, covers 0.3 % of this area

Biotite tonalite - Dark-gray; found in southeastern and western New Hampshire.

Lithology: tonalite

Ammonoosuc Volcanics, Felsic metavolcanic rocks (Middle - Upper Ordovician) at surface, covers 0.8 % of this area

Ammonoosuc Volcanics, Felsic metavolcanic rocks.

Lithology: felsic metavolcanic rock

Littleton Formation, Epiclastic metavolcanic sediments (Lower Devonian) at surface, covers 0.4 % of this area

Littleton Formation, Epiclastic metavolcanic sediments.

Lithology: metavolcanic rock

Two-mica granite of northern and southeastern New Hampshire (Early - Late Devonian) at surface, covers 0.2 % of this area

Two-mica granite of northern and southeastern New Hampshire - Similar to Concord Granite.

Lithology: granite

Biotite granodiorite (Late Ordovician) at surface, covers 0.7 % of this area

Biotite granodiorite.

Lithology: granodiorite

Moat Volcanics (Middle Jurassic?) at surface, covers 0.1 % of this area

Moat Volcanics - Bedded and ignimbritic tuffs, flows, and breccias; also porphyritic rhyolite and minor trachyte.

Lithology: ignimbrite; ash-flow tuff; volcanic breccia (agglomerate); rhyolite; trachyte

Gabbro (Jurassic) at surface, covers < 0.1 % of this area

Gabbro - Has varying amounts of olivine, augite, and hornblende.

Lithology: gabbro

Partridge Formation, White quartz-kyanite rock (Middle - Upper Ordovician) at surface, covers < 0.1 % of this area

Partridge Formation, White quartz-kyanite rock.

Lithology: schist

Biotite granite (Late Ordovician) at surface, covers 5 % of this area

Biotite granite - Pink, moderately to weakly foliated.

Lithology: granite

Porphyritic hornblende or alkalic amphibole quartz syenite (Jurassic) at surface, covers 0.5 % of this area

Porphyritic hornblende or alkalic amphibole quartz syenite.

Lithology: quartz syenite