Key: Mainly Marine Stratified Sequence

• Quaternary
  • Qh Holocene
  • Qp Pleistocene
  • Q Quaternary
  • Limits of Pleistocene glacial deposits
• Tertiary
  • Tp Pliocene
  • Tm Miocene
  • To Oligocene
  • Te3 Eocene Jackson Group
  • Te2 Eocene Claihorne Group
  • Te1 Eocene Wilcox Group
  • Te Eocene
  • Ts Paleocene
• Cretaceous
  • uK4 Navarro Group
  • uK3, uK3b, Uk3a Taylar Group
  • uK2 Austin and Eagle Ford Group
  • uK1 Woodhine and Tuscaloosa Groups
  • uK Upper Cretaceous
  • lK3 Washita Group
  • lK2 Fredericksburg Group
  • lK1 Trinity Group
  • lK lower Cretaceous
• Triassic-Jurassic
  • J Jurassic
  • JTr Lower Jurassic and Upper Triassic
  • Tr Triassic
  • lMz lower Mesozoic
• Permian
  • P4 Oehoan Series
  • P3b Upper part of Guadalupian Series
  • P3a Lower part of Guadalupian Series
  • P3 Guadalupian Series
  • P2b Upper part of Leonardian Series
  • P2a Lower part of Leonardian Series
  • P1 Wolfcampian Series
  • P Permian
• Pennsylvanian
  • PP4 Virgilian Series
  • PP3 Missourian Series
  • PP2 Des Moinesian Series
  • PP1 Mulkan and Morrowan Series
  • PP1a Arnkan and Morrowan Series, Jackson Sandstone
  • uPz Upper Paleozoic clastic wedge sequence
  • uPz Upper Paleozoic
  • PP Pennsylvanian
• Mississippian
  • M3 Chesterian Series
  • M2 Merantecian Series
  • M1 Osagean and Kinderkookian Series
  • M Mississippian
• Devonian
  • D3 Upper Devonian
  • D2 Middle Devonian
  • D1 Lower Devonian
  • D Devonian
• Silurian
  • S3 Upper Silurian (Cayugan)
  • S2 Middle Silurian (Niagaran)
  • S1 Lower Silurian (Alexandrian)
  • DS Devonian and Silurian
  • S Silurian
• Ordvician
  • O3 Upper Ordovician (Cincinnatian)
  • O2 Middle Ordovician (Mohawkian)
  • O1, O1b, O1a Lower Ordovician (Canadian)
  • O Ordovician
  • lPz Lower Paleozoic
  • OC Cambrian-Ordovician
• Cambrian
  • C Cambrian
  • Cq basal Lower Cambrian clastic rocks
  • Precambrian
    • Z Precambrian sedimentary rocks
    • Y3 Missoula Group
    • Y2 Wallace, Siyeh and Helena Formations
    • Y1 Ravalli Group and Prichard Formation
    • Y Precambrian metasemimentary rocks
    • X Precambrian metasedimentary rocks
    • W metasedimentary rocks