The San Andres Formation in the Palo Duro Basin is a middle Permian carbonate-evaporite sequence situated between two red-bed units, the underlying Glorieta and the overlying undifferentiated Queen-Grayburg sequences. The San Andres Formation, deposited during relative structural quiescence in the region, is composed of cyclic sequences of dark anhydritic mudstone, skeletal limestone, dolomite, nodular anhydrite, bedded anhydrite, and halite.

The Fleming Group and its basinward equivalents constitute the stratigraphic record of one of the major Cenozoic depositional episodes of the northern Gulf Coast Basin. The depositional sequence representing the episode is bounded above by the Amphistegina B shale and below by the Anahuac shale. Initially, lower Miocene (Oakville) progradation advanced across the broad submerged shelf platform constructed during earlier Frio deposition. When outbuilding reached the Frio paleocontinental margin, the rate slowed as large-scale growth faulting created a narrow lower Miocene expansion zone.