Abstract Upper Pennsylvanian strata were correlated in 2,500 wells in 28,000 square miles of north-central Texas. The mapped area is representative of the late Paleozoic Eastern Shelf of the Midland Basin. The mapped strata were subdivided into 22 nearly isochronous stratal intervals. After constructing structural and isopachous maps, facies maps of sandstone, limestone, and shale distribution were made that included percentage isolith, ratio, three-component, and trend-surface maps. Only the results of trend-surface maps of sandstone facies are presented here. Fitting trend surfaces to sandstone percentage allows interpretation of both depositional environment and provenance. The patterns of positive residuals in fourth order polynomial trend-surface maps of sandstone percentage permit recognition of deltas and bars. Examples of deltaic advance and retreat, as well as the reworking of older deltaic deposits into bar deposits, are apparent in map sequences of successive intervals. The interpretation of the positive residuals and trend-surfaces supports provenance migration during late Pennsylvanian deposition, when source areas of terrigenous detritus existed both north and east of the Eastern Shelf.