Fine crystalline, silty, cherty dolomite, and oolitic chert with local sandstone beds.
Sandstone, chert and interbedded dolomite
Coarse - crystalline cherty dolomite with a basal Gunter Sandstone Member.
Alluvium - clay, silt, sand, and gravel.
Undifferentiated (Ordovician rocks)
St. Peter Sandstone, Everton Formation
Eminence Dolomite - dolomite with some druse - coated chert. Potosi Dolomite - dolomite with abundance of druse - coated chert.
Keokuk Limestone, Burlington Limestone, Elsey Formation, Reeds Spring Formation, Pierson Limestone, Fern Glen Formation.
Decorah Group, Plattin Group
Northview Shale, Sedalia Formation, Compton Limestone, Bachelor Formation Chouteau Group, Hannibal Shale, Horton Creek Limestone.
Joachim Dolomite, Dutchtown Formation
Leemon Formation, Maquoketa Group including: (Girardeau Limestone, Orchard Creek Shale, Thebes Sandstone, Cape La Croix Shale), Cape Limestone, Kimmswick Limestone, Noix-Cyrene Limestone, Maquoketa Shale.
Chattanooga Shale, Sylamore Sandstone, Fortune Formation, Holts Summit Sandstone, Snyder Creek Shale, Cedar Valley Limestone, Louisiana Limestone, Saverton Shale, Grassy Creek Shale, Turpin Sandstone, Bushberg Sandstone, Glen Park Limestone, St. Larent Limestone, Beauvais Sandstone, Grand Tower Limestone, Clear Creek Chert, Little Saline Limestone, Grassy Knob Chert, Bailey Formation.
Cabaniss Subgroup - cyclic deposits, shale, sandstone, clay and several workable coal beds. Krebs Subgroup - cyclic deposits, sandstone, siltstone, shale, clay and some workable coal beds.