Qt - Quaternary terrace deposits (sands and gravels)
Qal - Quaternary alluvium (muds, sands, and gravels)
Kt - Upper Cretaceous Taylor Formation (marls)
Kau - Upper Cretaceous Upper Austin Formation (limestone)
Kam - Upper Cretaceous Middle Austin Formation (limestone)
Kal - Upper Cretaceous Lower Austin Formation (limestone)
Kef - Upper Cretaceous Eagle Ford Formation (shales)
Kwb - Upper Cretaceous Woodbine Formation (sands and sandy shales)