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

Geologic units in Benson county, North Dakota

Glacial Sediment- Collapsed Glacial Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 24 % 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

Glacial Sediment- Glacial Sediment Draped Over Pre-existing Topography (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 17 % 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 0.8 % of this area

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

Lithology: shale

Coleharbor Formation- River Sediment- Collapsed River Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 0.8 % 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). Faulted and contorted supraglacial sediment with hummocky topography.

Lithology: sand; gravel

Glacial Sediment- Collapsed Glacial Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 7 % 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

Coleharbor Formation- Offshore Sediment- Ice-Walled Lake Sediment or Collapsed Supraglacial-Lake Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 0.5 % of this area

Laminated silt and clay of glacier-dammed lakes; as thick as 60 meters (200 feet). Flat-bedded sediment elevated above surrounding area or floded sediment with hummocky topography.

Lithology: silt; clay or mud

Coleharbor Formation- Offshore Sediment- Proglacial Lake Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 0.3 % 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

Oahe Formation- Pond Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 6 % of this area

Dark, obscurely bedded clay and silt; typically a few meters thick; in modern ephemeral ponds.

Lithology: clay or mud; silt

Glacial Sediment- Collapsed/Draped Transition Sediments (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 22 % 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

Fox Hills Formation (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 0.9 % of this area

Olive-brown sand, shale, and sandstone; marine shoreline and offshore sediment; as thick as 120 meters (400 feet).

Lithology: sand; shale; sandstone

Coleharbor Formation- River Sediment- Uncollapsed River Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 8 % 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 0.6 % 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

Oahe Formation- Windblown Sand (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 0.1 % of this area

Well-sorted, medium sand with obscure bedding; poorly developed palesols common; as thick as 10 meters (30 feet); knobby topography consisting of inactive transverses or longitudinal dunes nearly obliterated by more recent blowouts.

Lithology: sand

Glacial Sediment- Collapsed Glacial Sediment (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 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 1.0 % 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- Glacial Sediment on Thrust Masses (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers 7 % 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