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Lacustrine Sediments

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).
State South Dakota
Name Lacustrine Sediments
Geologic age Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]
Primary rock type clay or mud
Secondary rock type silt
Other rock types sand; gravel
Lithologic constituents
Major
Unconsolidated > Fine-detrital > Clay (Lacustrine)
Unconsolidated > Fine-detrital > Silt (Lacustrine)
Minor
Unconsolidated > Coarse-detrital > Sand (Lacustrine)
Unconsolidated > Coarse-detrital > Gravel (Lacustrine)
Map references
Martin, J. E., Sawyer, J. F., Fahrenbach, M. D., Tomhave, D. W., and Schulz, L. D., 2004, Geologic Map of South Dakota: South Dakota Geological Survey
Unit references
Martin, J. E., Sawyer, J. F., Fahrenbach, M. D., Tomhave, D. W., and Schulz, L. D., 2004, Geologic Map of South Dakota: South Dakota Geological Survey
Counties Beadle - Brown - Campbell - Codington - Day - Deuel - Faulk - Hamlin - Hand - Hughes - Kingsbury - Lake - Marshall - Minnehaha - Potter - Roberts - Spink