Reconstructs the depositional history of a late Holocene archaeological site, Cowpen Slough (16 CT 147) in the Catahoula Lowlands of east central Louisiana, and places that history in regional context. Procedures including grain-size analysis, field descriptions of soil horizons, x-ray diffraction of clay minerals, and total element analysis are employed to build a description of depositional units and parent material present in on-site sediment samples and off-site subsurface core samples. To infer source, results of tests are integrated with radiocarbon dates and Saucier's chronology for this section in the Lower Mississippi Valley. Authors suggest that between 6000 and 4790 BP the Arkansas was the source of sediment present in the archaeological deposit. After 4790 BP sediments were deposited by the Mississippi river system.