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Mineral Resources > Online Spatial Data > Geology > by state > North Dakota Geology

Geologic units in Grand Forks county, North Dakota

Syntectonic to pretectonic granitoid rocks (Late Archean) at surface, covers < 0.1 % of this area

Syntectonic to pretectonic granitoid rocks - Granite and granodiorite of the Vermilion Granitic Complex, the Giants Range and Bemidji batholiths, as well as smaller intrusions of tonalite and monzonite of the Algoman orogen in northern Minnesota. Also includes the Odessa, Sacred Heart, and Fort Ridgely Granites exposed along the Minnesota River Valley in southwestern Minnesota.

Lithology: granite; granodiorite; tonalite; monzonite

Middle and Upper Ordovician rocks, undivided (Middle and Late Ordovician) at surface, covers < 0.1 % of this area

Middle and Upper Ordovician rocks, undivided - Sandstone and shaly sandstone of the Winnipeg Formation and limestone and dolomitic limestone of the Red River Formation along the east edge of the Williston Basin in northwestern Minnesota

Lithology: sandstone; limestone

Coleharbor Formation- Offshore Sediment- Proglacial Lake Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 28 % of this area

Laminated silt and clay of glacier-dammed lakes; as thick as 60 meters (200 feet). Flat-bedded sediment of low-lying plains

Lithology: silt; clay or mud

Coleharbor Formation- River Sediment- Uncollapsed River Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 3 % of this area

Moderately well sorted cross-bedded sand and plane-bedded gravel, including sediment of melt-water and other rivers; as thick as 30 meters (100 feet). Flat-bedded sediment of gently sloping plains and terraces, commonly with braided-channel scars.

Lithology: sand; gravel

Sand of the Oahe and Older Formations, Undivided (Phanerozoic | Cenozoic | Tertiary Quaternary | Pliocene Pleistocene(?) Holocene) at surface, covers 1.0 % of this area

Windblown sand of the Oahe Formation, as thick as 3 meters (10 feet), and sand of older formations with an undulating wind-scoured surface.

Lithology: sand

Glacial Sediment- Collapsed Glacial Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 0.4 % of this area

Unbedded, unsorted mixture of clay, silt, sand, and pebbles, and a few cobbles and boulders; as thick as 30 meters (100 feet)

Lithology: clay or mud; silt; sand; gravel

Oahe Formation- River Sediment (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 18 % of this area

Dark, obscurely bedded clay and silt (overbank sediment); generally overlying cross-bedded sand (channel sediment); as thick as ten meters (30 feet); on flood plains of modern streams.

Lithology: clay or mud; silt; sand

Glacial Sediment- Collapsed Glacial Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 18 % of this area

Unbedded, unsorted mixture of clay, silt, sand, and pebbles, and a few cobbles and boulders; as thick as 30 meters (100 feet)

Lithology: clay or mud; silt; sand; gravel

Granite-rich migmatite (Late Archean) at surface, covers < 0.1 % of this area

Granite-rich migmatite - Granitic gneiss, paragneiss, schist, and migmatite in the Vermillion Granitic Complex, and other parts of extreme northern Minnesota. Grades into granitoid rocks.

Lithology: gneiss; schist; migmatite

Spring Pits (Phanerozoic | Cenozoic | Quaternary ) at surface, covers 1 % of this area

Spring pits, west and north of Grand Forks

Lithology: sand

Multiphase intrusions of hornblende-pyroxene-bearing and biotite-bearing monzonite, monzodiorite, diorite, syenite, and granodiorite (Late Archean) at surface, covers < 0.1 % of this area

Multiphase intrusions of hornblende-pyroxene-bearing and biotite-bearing monzonite, monzodiorite, diorite, syenite, and granodiorite - Typically postdates regional metamorphism and deformation associated with the Algoman orogen.

Lithology: monzonite; monzodiorite; diorite; syenite; granodiorite

Glacial Sediment- Wave-Eroded Glacial Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 30 % of this area

Unbedded, unsorted mixture of clay, silt, sand, and pebbles, and a few cobbles and boulders; as thick as 30 meters (100 feet)

Lithology: clay or mud; silt; sand; gravel

Pierre Formation (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 0.6 % of this area

Dark-gray shale; marine offshore sediment; maximum outcrop thickness is a few hundred meters.

Lithology: shale

Niobrara and Carlile Formations, Undivided (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers < 0.1 % of this area

Niobrara Formation: light-brown to dark-gray calcareous shale; offshore marine sediment; maximun outcrop thickness is 45 meters (150 feet). Carlile Formation: dark-gray shale; marine offshore sediment; maximum outcrop thickness is 30 meters (100 feet).

Lithology: shale

Mafic metavolcanic rocks (Late Archean) at surface, covers < 0.1 % of this area

Mafic metavolcanic rocks - Dominantly basalt that contains thin sedimentary units, including iron-formation. Includes parts of the Ely Greenstone and the Newton Lake Formation in northeastern Minnesota. Also includes metabasalt exposed in the Minnesota River Valley.

Lithology: basalt; sedimentary rock; iron formation; meta-basalt