Geologic units in Saint Louis county, Missouri

Meramecian Series (Late Mississippian-Meramecian Series) at surface, covers 33 % of this area

St. Louis Limestone, Salem Formation, Warsaw Formation.

Osagean Series (Early Mississippian-Osagean Series) at surface, covers 15 % of this area

Keokuk Limestone, Burlington Limestone, Elsey Formation, Reeds Spring Formation, Pierson Limestone, Fern Glen Formation.

Holocene series (Quaternary-Holocene Series) at surface, covers 14 % of this area

Alluvium - clay, silt, sand, and gravel.

Cherokee Group - Cabaniss Subgroup, Krebs Subgroup (Middle Pennsylvanian-Middle Series-Desmonian Stage) at surface, covers 13 % of this area

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.

Marmaton Group (Middle Pennsylvanian-Middle Series-Desmonian Stage) at surface, covers 12 % of this area

Cyclic deposits, shale and limestone with sandstone, clay and several coal beds, some workable.

Decorah Group, Plattin Group (Middle Ordovician-Mohawkian Series) at surface, covers 4 % of this area

Decorah Group, Plattin Group

Pleasanton Group (Late Pennsylvanian-Upper Series-Missourian Stage) at surface, covers 3 % of this area

Dominantly shale and sandstone with minor coal.

Joachim Dolomite, Dutchtown Formation (Middle Ordovician-Mohawkian Series) at surface, covers 2 % of this area

Joachim Dolomite, Dutchtown Formation

St. Peter Sandstone, Everton Formation (Middle Ordovician to Early Ordovician) at surface, covers 2 % of this area

St. Peter Sandstone, Everton Formation

Leemon Formation, Maquoketa Group, Cape Limestone, Kimmswick Limestone, Noix-Cyrene Limestone, Maquoketa Shale (Late Ordovician to Middle Ordovician) at surface, covers 2 % of this area

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.

Devonian System (Late to Early Devonian) at surface, covers 0.6 % of this area

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.

Kinderhookian Series (Early Mississippian-Kinderhookian Series) at surface, covers 0.2 % of this area

Northview Shale, Sedalia Formation, Compton Limestone, Bachelor Formation Chouteau Group, Hannibal Shale, Horton Creek Limestone.

Smithville Dolomite, Powell Dolomite, Cotter Dolomite, Jefferson City Dolomite (Early Ordovician-Ibexian Series) at surface, covers < 0.1 % of this area

Fine crystalline, silty, cherty dolomite, and oolitic chert with local sandstone beds.

Pennsylvanian Undifferentiated (Pennsylvanian) at surface, covers < 0.1 % of this area

Pennsylvanian Undifferentiated

Silurian system (Late Silurian- to Early Silurian) at surface, covers < 0.1 % of this area

Joliet Limestone, Bowling Green Dolomite, Bryant Knob Formation, Bainbridge Formation, Sexton Creek Limestone.

St. Louis Limestone (Mississippian (Visean)) at surface, covers < 0.1 % of this area

St. Louis Limestone.