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

Geologic units in Buffalo county, South Dakota

Till, Stagnation Moraine (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 37 % of this area

Heterogeneous, clay with silt to boulder-size clasts of glacial orgin. A geomorphic feature that is characterized by hummocky terrain with abundant sloughs resulting from stagnation of ice sheets. Composite thickness of all Upper Wisconsin till may be up to 300 ft (91 m).

Lithology: clay or mud; silt; sand; gravel

Niobrara Formation (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 0.1 % of this area

White to dark gray argillaceous chalk, marl, and shale. Weathers yellow to orange. Contains thin, laterally continuous bentonite beds, chalky carbonaceous shale, minor sand, and small concretions. Thickness 160-225 ft (49-69 m).

Lithology: limestone; limestone; shale; clay or mud; sand

Eolian Deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers 5 % of this area

(loess and sand dune) Silt to medium-grained sand. Deposited as sand sheets and barchan, linear, and dome-like dunes and as veneer on uplands. Thickness up to 300 ft (91m).

Lithology: silt; sand

Till, Ground Moraine (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 1 % of this area

Heterogeneous, clay with silt to boulder-size clasts of glacial orgin. A geomorphic feature that is characterized by smooth, rolling terrain. Composite thickness of all Upper Wisconsin till may be up to 300 ft (91 m).

Lithology: clay or mud; silt; sand; gravel

Terrace Deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.5 % of this area

Clay to boulder-size clasts deposited as pediments, paleochannels, and terrace fills of former flood plains. Thickness up to 75 ft (23m).

Lithology: clay or mud; silt; sand; gravel

Dam (None) at surface, covers < 0.1 % of this area

Lithology: indeterminate

Pierre Shale (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 35 % of this area

Blue-gray to dark-gray, fissile to blocky shale with persistent beds of bentonite, black organic shale, or light-brown chalky shale. Contains minor sandstone, conglomerate, and abundant carbonate and ferruginous concretions. Thickness 1,000-2,700 ft (305-823 m).

Lithology: shale; clay or mud; sandstone; conglomerate

Outwash, Terrace (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 4 % of this area

Heterogeneous clay to gravel of glaciofluvial orgin. Thickness up to 60 ft (18m)

Lithology: clay or mud; silt; sand; gravel

Alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 14 % of this area

Clay to boulder-size clasts with locally abundant organic material. Thickness up to 75 ft (23m).

Lithology: clay or mud; silt; sand; gravel

Outwash, Collapsed (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 1 % of this area

Heterogeneous sand and gravel of glaciofluvial orgin. Deposited as outwash sediments that collapsed due to melting of buried ice. Thickness up to 90 ft (27m).

Lithology: sand; gravel