The Pennsylvanian foreland province of Texas and eastern New Mexico covers approximately 150,000 square miles. Over this whole area close relationships exist between structural and sedimentary developments. Originally a marginal segment of the mid-Paleozoic craton, it was isolated from the ocean by borderland mountain ranges. Uplift of these Llanorian ranges altered the early continental shelf block into an incipient mediterranean, notching deeply into the cratonic core. The eastern margin of this intra-continental seaway was almost continuously loaded with clastic sediments. Extensive limestone banks spread across the unloaded marginal shallows farther west. Uplifted positive blocks and topographic highs within the negative interior supported isolated limestone buildups. Intervening clastic and carbonate-starved deeps accumulated thin sections of dark shales. Facies changes associated with environmental boundaries limit embayment stratigraphic correlations.