"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"