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Geologic units in Jerauld county, South Dakota

Till, Minor Moraine (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 43 % of this area

Heterogeneous, clay with silt to boulder-size clasts of glacial orgin. A geomorphic feature that is characterized by elevated linear ridges including minor, washboard, or recessional moraines. Composite thicknessof all Upper Wisconsin till may be up to 300 ft (91 m).

Lithology: clay or mud; silt; sand; gravel

Till, Stagnation Moraine (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 24 % 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

Till, Ground Moraine (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 14 % 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

Outwash, Collapsed (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 8 % 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

Outwash, Undifferentiated (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 5 % of this area

Heterogeneous sand and gravel, with minor clay and silt. Deposits of glaciofluvial orgin including outwash plains, kame terraces, and other undifferentiated deposits. Thickness up to 30 ft (9m).

Lithology: sand; gravel; clay or mud; silt

Till, End Moraine (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 3 % of this area

Heterogeneous, clay with silt to boulder-size clasts of glacial orgin. A geomorphic feature that is characterized by elevated linear ridges with hummocky terrain locally at former ice sheet margins. Composite thicknessof all Upper Wisconsin till may be up to 300 ft (91 m).

Lithology: clay or mud; silt; sand; gravel

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

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

Lithology: clay or mud; silt; sand; gravel

Pierre Shale (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 0.9 % 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).

Alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.8 % 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