Geologic units in Walsh county, North Dakota

Additional scientific data in this geographic area

Pierre Formation (Upper Cretaceous) at surface, covers 30 % of this area

Dark-gray shale; marine offshore sediment; as thick as 700 metres (2,300 feet).

Mowry-Skull Creek, Undivided (Lower to Upper Cretaceous) at surface, covers 23 % of this area

Mowry, Newcastle, and Skull Creek Formations (as described in Kbs).

Inyan Kara (Lower Cretaceous) at surface, covers 15 % of this area

Light-gray, fine to coarse sandstone and gray shale; river, lake, and nearshore marine sediment; as thick as 135 metres (450 feet).

Belle Fourche Formation (Upper Cretaceous) at surface, covers 9 % of this area

Medium- to dark-gray, silty to sandy shale; marine offshore sediment; as thick as 105 metres (350 feet).

Carlile Formation (Upper Cretaceous) at surface, covers 7 % of this area

Dark-gray shale; marine offshore sediment; as thick as 120 metres (400 feet).

Undifferentiated Jurassic Sediments (Jurassic) at surface, covers 6 % of this area

Dark-gray, greenish, and varicolored shale with local limestone (Swift and Rierdon Formation equivalents); mainly nearshore marine sediments; as thick as 180 metres (600 feet).

Niobrara Formation (Upper Cretaceous) at surface, covers 5 % of this area

Light-brown to dark-gray calcareous shale; marine offshore sediment; as thick as 75 metres (250 feet).

Greenhorn Formation (Upper Cretaceous) at surface, covers 3 % of this area

Dark-gray calcareous shale; marine offshore sediment; as thick as 45 metres (150 feet).

Red River Formation (Ordovician) at surface, covers 0.9 % of this area

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

Upper Ordovician (Upper Ordovician) at surface, covers 0.2 % 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 < 0.1 % of this area

Shale, limestone, dolomite, siltstone, and sandstone.