Depositional Environment of the Tombigbee Sand Member - Mooreville Formation Contact at Selected Outcrops in Alabama

A study was made of eighteen samples collected at four selected exposures of the contact of the Eutaw and Selma groups (Tombigbee Sand Member and Mooreville Formation) of Late Cretaceous (Austinian) age in central and west-central Alabama. The sediments consisted primarily of quartz sand and glauconite with muscovite and garnet secondary in abundance in the clastic fraction. Several of the samples were calcareous. Particle size analysis, fossils, and mineral content indicate the depositional environment before and after the erosional cycle between Tombigbee and Mooreville sedimentation was neritic and more likely epineritic. Certain areas of deposition may have existed as quite bays and lagoons as part of the shoreline as evidenced by the presence of glauconite and pyrite.