Geologic units in Belknap county, New Hampshire

Additional scientific data in this geographic area

Upper part of Rangeley Formation (Lower Silurian (Llandoverian)) at surface, covers 27 % of this area

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.

Lower part of Rangeley Formation (Lower Silurian (Llandoverian)) at surface, covers 20 % of this area

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.

Kinsman Granodiorite (Early Devonian) at surface, covers 16 % of this area

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

Winnipesaukee Tonalite (Early Devonian) at surface, covers 16 % of this area

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

Perry Mountain Formation, undivided (Lower? - Middle? Silurian) at surface, covers 6 % of this area

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

Concord Granite (Late Devonian) at surface, covers 6 % of this area

Gray two-mica granite, locally grading to tonalite.

Conway Granite (Middle - Late? Jurassic) at surface, covers 2 % of this area

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

Augite monzodiorite (Jurassic) at surface, covers 2 % of this area

Augite monzodiorite.

Quartz syenite (Jurassic) at surface, covers 2 % of this area

Commonly porphyritic and mesoperthitic; contains biotite and, locally, fayalite, hastingsite, hornblende, or ferrohedenbergite.

Diorite (Jurassic) at surface, covers 1 % of this area

Contains hornblende, biotite, and hedenbergite.

Porphyritic syenite (Jurassic) at surface, covers 1 % of this area

Hastingsite or hornblende and (or) hedenbergite are present.

Mesoperthitic biotite granite (Early Cretaceous) at surface, covers 0.8 % of this area

Pink Conway-type granite of Kingsley (1931).

Porphyritic granite (Jurassic) at surface, covers 0.7 % of this area

Porphyritic granite.

Rangeley Formation, Ribbon-banded calc-silicate of eastern New Hampshire (Lower Silurian (Llandoverian)) at surface, covers 0.2 % of this area

Probably equivalent to Patch Mountain Member of the Sangerville Formation (Llandoverian and Wenlockian) of central Maine.

Porphyritic biotite granite (Cretaceous) at surface, covers 0.2 % of this area

Pink to gray; hastingsite or riebeckite in some varieties.

Smalls Falls Formation, undivided (Upper to Middle Silurian (Ludlovian and Wenlockian)) at surface, covers 0.2 % of this area

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.

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

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

Rhyolite and fine-grained granite (Cretaceous) at surface, covers < 0.1 % of this area

Includes some ignimbritic caldera-fill and minor intrusive rocks (part of Ossipee Mountain Complex of Kingsley, 1931); also some aphanitic gray, black, or tan quartz-feldspar porphyry.

Hornblende-biotite quartz monzodiorite (Jurassic) at surface, covers < 0.1 % of this area

Composition ranges from quartz monzonite to diorite.

Littleton Formation, undivided (Lower Devonian; Siegenian) at surface, covers < 0.1 % of this area

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

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

Has varying amounts of olivine, augite, and hornblende.