Banded, dark-green, reddish-brown, and white iron-formation, ferruginous chert, and minor mica schist. Includes three or more ages of oxide-, carbonate-, silicate-, and sulifide-facies iron-formation and interbedded tuffaceous rocks. Thickness 20-500 ft (6-152 m).
State South Dakota
Name Iron-Formation
Geologic age Early Proterozoic
Lithologic constituents
Sedimentary > Chemical > Banded-iron-formation (Bed)
Sedimentary > Chemical > Chert (Bed)
Metamorphic > Schist > Mica-schist

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, GM 10, scale 1:500,000.

NGMDB product
Counties Custer - Lawrence - Pennington