Geologic units in Kittson county, Minnesota

Upper Ordovician (Upper Ordovician) at surface, covers 61 % of this area

Limestone, shaley limestone, and dolostone; includes the Maquoketa Formation, and the Stewartville, Prosser, and Cummingsville Formations of the Galena Group. Also includes limestone and dolostone of the Red River Formation, and sandstone and shale of the Winnipeg Formation in northwest Minnesota.

Hallock Red Beds (Jurassic) at surface, covers 13 % of this area

Shale, limestone, dolomite, siltstone, and sandstone.

Granitic to granodioritic orthogneiss (Neoarchean) at surface, covers 6 % of this area

Granitic to granodioritic orthogneiss. Includes the McGrath Gneiss (~2,752 ± 15, 2,557 Ma) and unnamed units.

Foliated to gneissic tonalite, granodiorite, and diorite (Neoarchean) at surface, covers 5 % of this area

Foliated to gneissic tonalite, granodiorite, and diorite. Includes the Lookout Mountain tonalite (~2,718 Ma) of the Giants Range batholith and other intrusions within batholithic complexes defined by a low-to-moderate gravity signature with magnetic foliation apparent from aeromagnetic maps.

Undifferentiated (Cenomanian to Campanian) at surface, covers 5 % of this area

Conglomerate, sandstone, mudstone, shale, marlstone, siltstone, and minor lignite, deposited in marine and non-marine settings; likely Cenomanian to Campanian age. Unit outline is the product of contouring the stratigraphic top and base, from which an isopach grid was created. Because the distribution is patchy, unit boundaries were drawn from the gridded data to represent locations where more than 25 feet (8 meters) of thickness occurs. As a result, many areas outside of the unit boundaries may be overlain by thin Cretaceous strata and the unit is depicted without a contact line.

Granitic intrusion (Neoarchean) at surface, covers 3 % of this area

Granitic intrusion. Includes the Sacred Heart (~2592, 2,603 Ma) and Ortonville granites, the Shannon Lake Granite (~2,674), and other intrusions having low gravity and magnetic signatures.

Granodiorite to hornblende diorite, locally magmatically foliated (Neoarchean) at surface, covers 3 % of this area

Granodiorite to hornblende diorite, locally magmatically foliated. Includes the Britt Granodiorite (~2,685 Ma) and other intrusions having moderate gravity and magnetic signatures.

Schist and tonalitic to granodioritic paragneiss (Neoarchean) at surface, covers 2 % of this area

Schist and tonalitic to granodioritic paragneiss. Typically adjacent to large batholithic complexes.

Red River Formation (Ordovician) at surface, covers 0.2 % of this area

Yellowish- to brownish-gray limestone and dolomite; offshore marine sediment; as thick as 215 metres (700 feet).

Piper Formation Equivalent (Jurassic) at surface, covers < 0.1 % of this area

White to buff, brown, or gray limestone, gypsum, and anhydrite; offshore marine sediments; as thick as 190 metres (625 feet).

Volcaniclastic rocks of felsic to intermediate composition (Neoarchean) at surface, covers < 0.1 % of this area

Volcaniclastic rocks of felsic to intermediate composition.