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Colluvium

Clay to boulder-size clasts forming rubble residuum and talus. Thickness up to 30 ft (9m).
State South Dakota
Name Colluvium
Geologic age Phanerozoic | Cenozoic | Quaternary
Primary rock type clay or mud
Secondary rock type silt
Other rock types sand; gravel
Lithologic constituents
Major
Unconsolidated > Fine-detrital > Clay (Colluvial)
Unconsolidated > Fine-detrital > Silt (Colluvial)
Unconsolidated > Coarse-detrital > Sand (Colluvial)
Unconsolidated > Coarse-detrital > Gravel (Colluvial)
Unconsolidated > Coarse-detrital > Boulders (Colluvial)
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 Lawrence - Lyman - Meade - Mellette - Pennington - Perkins - Walworth