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

Geologic units in Minnehaha county, South Dakota

Outwash, Undifferentiated (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Illinoian(?) Pre-Illinoian]) at surface, covers 2 % of this area

Heterogeneous sand and gravel with minor clay of glaciofluvial orgin. Thickness up to 90 ft (27 m).

Lithology: sand; gravel; clay or mud

Lacustrine Sediments (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 0.3 % of this area

Glaciolacustrine clay and silt with minor sand and gravel. Forms flat, low-lying terrain. Includes deposits from Glacial Lake Dakota and Glacial Lake Agassiz. Thickness up to 60 ft (18m).

Lithology: clay or mud; silt; sand; gravel

Outwash, Collapsed (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 2 % 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

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

Till, Ground Moraine (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Illinoian(?)]) at surface, covers 12 % of this area

Heterogeneous, clay with silt to boulder-size clasts. Exhibits a distinctive weathered, dissected surface. Contains prominent oxidized joints and fractures with gypsum or calcite. Typically overlain by up to 25 ft (8 m) of loess. Thickness up to 120 ft (37 m).

Lithology: clay or mud; silt; sand; gravel

Lacustrine Sediments, Ice-walled (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 0.2 % of this area

Glaciolacustrine clay and silt with minor sand and gravel. Forms elevated level terrain. Thickness up to 60 ft (18m).

Lithology: clay or mud; silt; sand; gravel

Eolian Deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers < 0.1 % 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

Sioux Quartzite (Proterozoic | Paleoproterozoic) at surface, covers 0.8 % of this area

Pink, reddish to tan, siliceous, fine to coarse-grained, iron-stained orthoquartzite with minor conglomerate and mudstone layers. Estimated thickness greater than 1,000 ft (305 m).

Lithology: quartzite; conglomerate; mudstone

Till, End Moraine (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 16 % 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

Till, Stagnation Moraine (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 16 % 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

Outwash, Terrace (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 0.1 % of this area

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

Lithology: clay or mud; silt; sand; gravel

Clayely Till, Ground Moraine (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Pre-Illinoian]) at surface, covers 31 % of this area

Heterogeneous, clay to boulder-size clasts of glacial orgin. Exhibits a distinctive weathered, dissected surface. Contains prominent oxidized joints and fractures with gypsum or calcite. Typically overlain by up to 45 ft (14 m) of loess. Thickness of uppermost Pre-Illinoian till may be up to 120 ft (37 m). Composite thickness of all Pre-Illinoian till may be up to 1,000 ft (305 m).

Lithology: clay or mud; silt; sand; gravel

Outwash, Valley Train (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 6 % of this area

Heterogeneous silt to gravel. Confined to valleys of glaciofluvial orgin. Thickness up to 60 ft (18m).

Lithology: silt; sand; gravel

Till, Ground Moraine (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers 0.7 % 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