A rock model for the upper Carboniferous orthoquartzitic sandstone complexes of northern Alabama is constructed through examination of outcrops which are large enough to show the patterns of both vertical and horizontal variation. This rock model is never present in its entirety in any single exposure, but all outcrops of the orthoquartzitic sandstone can be explained in terms of their relation to the model. The characteristics of the model are consistent with modern shoreline features and establish that the sandstone bodies are representative of beach- and barrier-island situations. Paleogeographic reconstruction, utilizing seaward directions as indicated by the beach-barrier complexes, reveals two directions of sediment influx, one from the northeast and one from the south. These two systems merged in north-central Alabama, causing the sea to withdraw toward the northwest.