"Millersville Limestone Member" "Mincke Member" "Misenheimer Shale Member" "Mississippian Subsystem" "Missourian Series" "Moccasin Springs Formation" "Modern Soil" "Modesto Formation" "Momence Sandstone Member" "Montrose Chert Member" "Mooseheart Member" "Moredock Member" "Morrowan Series" "Mortimer Member" "Morton Tongue" "Mosalem Formation" "Mounds Gravel" "Mt. Carmel Sandstone Member" "Mt. Rorah Coal Member" "Mt. Simon Sandstone" "Mulberry Grove Silt Member" "Murphysboro Coal Member" "Murray Bluff Sandstone Member" "Nachusa Formation" "Neda Formation" "Negli Creek Limestone Member" "New Albany Shale Group" "New Burnside Coal Member" "New Glarus Member" "New Haven Coal Member" "New London Member" "New Richmond Sandstone" "Niagaran Series" "Noix Oolite Member" "Nokomis Sandstone Member" "North Hill Group" "Nutwood Shale Member" "O'Nan Coal Member" "Oak Grove Limestone Member" "Oak formation" "Oakland Till Member" "Offerman Member" "Ogle Till Member" "Oglesby Member" "Okaw Group" "Omega Limestone Member" "Omphghent member" "Oneota Dolomite" "Opdyke Coal Member" "Orchard Creek Shale Member" "Ordovician System" "Otis Member" "Ottawa Limestone Megagroup" "Owl Creek Formation" "Paint Creek Group" "Paleocene Series" "Paleozoic Erathem" "Palestine Sandstone" "Pearl Formation" "Pecatonica Formation" "Peddicord Tongue" "Pennsylvanian Subsystem" "Peoria Silt" "Percy Limestone Member" "Petersburg Silt" "Peyton Colluvium" "Piasa Limestone" "Piatt Member" "Pike Soil" "Plaines Member" "Plano Silt Member" "Platteville Group" "Plattin Subgroup" "Pleasant Grove Soil" "Pleasantview Sandstone Member" "Pleistocene Series" "Pliocene Series" "Pokeberry Limestone Member" "Pond Creek Coal Member" "Popcorn Sandstone Member" "Pope Creek Coal Member" "Pope Megagroup" "Porters Creek Formation" "Post Creek Formation" "Potosi Dolomite" "Potsdam Sandstone Megagroup" "Pounds Sandstone Member" "Prairie du Chien Group" "Precambrian Erathem" "Prospect Hill Siltstone" "Proviso Siltstone Member" "Purington Shale Member" "Quaternary System" "Quimbys Mill Formation" "Raccoon Creek Group" "Racine Formation" "Radnor Till Member" "Ramp Creek Limestone Member" "Rapid Member" "Reel Limestone Member" "Reelsville Limestone Member" "Reisner Limestone Member" "Renault Limestone" "Rendleman Oolite Bed" "Reynoldsburg Coal Member" "Richmondian Stage" "Ridenhower Formation" "Rivoli Member" "Robein Member" "Roby Silt Member" "Rocher Member" "Rock Branch Coal Member" "Rock Island Coal Member" "Romeo Member" "Roodhouse coal bed" "Rosiclare Sandstone Member" "Roxana Silt" "Salem Limestone" "Sample Sandstone Member" "Sangamon Soil" "Sankoty Sand Member" "Sauk Sequence" "Saverton Shale" "Scales Shale" "Schweizer Member" "Scottsburg Limestone Member" "Scottville Limestone Member" "Seahorne Limestone Member" "Seelyville Coal Member" "Sellers Limestone Bed" "Seville Limestone Member" "Sexton Creek Limestone" "Shakopee Dolomite" "Sharpsboro Member" "Shelbyville Coal Member" "Sherwood Member" "Shetlerville Limestone Member" "Shoal Creek Limestone Member" "Shorewood Member" "Shullsburg Member" "Shumway Limestone Member" "Silurian System" "Sinsinawa Member" "Smithboro Till Member" "Snider Till Member" "Solon Member" "Sonora Formation" "Sorento Limestone Member" "Spar Mountain Sandstone Member" "Spechts Ferry Formation" "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" "Sweeney Formation" "Sweetland Creek Shale" "Sylamore Sandstone" "Tar Springs Sandstone" "Tarter Coal Member" "Teneriffe Silt" "Tertiary System" "Tete de Morts Formation" "Thebes Sandstone Member" "Tilton Till Member" "Tioga Bentonite Bed" "Tippecanoe Sequence" "Tiskilwa Formation" "Tonti Sandstone Member" "Toulon Member" "Trempealeauan Stage" "Trentonian Stage" "Tripp Limestone Member" "Trivoli Sandstone Member" "Troutman Member" "Trowbridge Coal Member" "Turner Mine Shale Member" "Two Rivers Member" "Tygett Sandstone Member" "Tyson Member" "Ullin Limestone" "Unnamed clastic member - Carbondale Formation" "Unnamed gray shale member - Carbondale Formation" "Upper Devonian Series" "Valmeyeran Series" "Vandalia Till Member" "Vergennes Sandstone Member" "Vermilionville Sandstone Member" "Victory Member" "Vienna Limestone" "Virgilian Series" "Wadsworth Formation" "Walche Limestone Member" "Walgreen Member" "Wall Member" "Walnut Grove Limestone Member" "Walshville Member" "Waltersburg Formation" "Wapsipinicon Limestone" "Warsaw Shale" "Wasco Member" "Wayside Member" "Wedron Group" "West Baden Group" "West Franklin Limestone Member" "West Lebanon Formation" "Wheeler Coal Member or Bed" "Wilcox Formation" "Wilhelmi Formation" "Will Scarlet Shale Member" "Willis Coal Member" "Winnebago Formation" "Winslow Till Member" "Wise Lake Formation" "Wise Ridge Coal Member" "Witt Coal Member" "Wolf Creek Formation" "Womac Coal Member" "Woodbury Limestone Member" "Wyota Member" "Yankeetown Sandstone" "Yarmouth Soil" "Yorkville Member"