Sandstone, chert and interbedded dolomite
Fine crystalline, silty, cherty dolomite, and oolitic chert with local sandstone beds.
Coarse - crystalline cherty dolomite with a basal Gunter Sandstone Member.
Eminence Dolomite - dolomite with some druse - coated chert. Potosi Dolomite - dolomite with abundance of druse - coated chert.
Derby-Doerun Dolomite - alternating thin dolomite, siltstone, and shale; Davis Formation - glauconitic shale with fine - grained sandstone, limestone, and dolomite); Bonneterre Dolomite - dolomite, dolomitic limestone, and limestone; glauconitic in lower part.
Sandstone with some dolomitic and shaly lenses; coarse - graines to conglomeratic and arkosic at base.
Keokuk Limestone, Burlington Limestone, Elsey Formation, Reeds Spring Formation, Pierson Limestone, Fern Glen Formation.