"Spoon Formation" "Spring Grove Member" "Springfield Coal Member" "Springville Shale" "St. Clair Limestone" "St. David Limestone Member" "St. James Member" "St. Louis Limestone" "St. Peter Sandstone" "Starrs Cave Limestone" "Starved Rock Sandstone Member" "State Pond Member" "Ste. Genevieve Limestone" "Sterling Till Member" "Stewartville Member" "Stillman Member" "Stonefort Limestone Member" "Strawbridge Member" "Sugar Run Formation" "Survant Coal Member"