A portion of the inner continental shelf in the northern Gulf of Mexico exhibits sinusoidal, submarine ridges and troughs oriented roughly 70° to the strand line. Almost perpendicular to the ridges and troughs are two linear sand bodies lying at 70 and 90 ft. (21 and 27 m) depths. A thin lamina of clayey silt covers the coarse, clean sands forming this topography. Sediments comprising the sand bodies are distinguishable from surrounding sediments by their larger grain size and higher heavy mineral content. The ridges display coarser, better sorted sediments with higher heavy mineral percentages than the troughs. It is proposed that the sand bodies originated as barrier islands and/or spits during the Late Wisconsin regression. Fluvial action cut the ridge and trough topography into the terrace and the recent, Wisconsin sea level rise modified the topography to its present form. Radiocarbon dates the youngest aspects of the 70 ft. deep sand body as at least 5,000 years B.P.