BENTHIC FORAMINIFERAL ASSEMBLAGES ACROSS THE EOCENE-OLIGOCENE BOUNDARY FROM THE PERDUE HILL QUARRY, ALABAMA

A series of 22 samples was collected from Eocene- Oligocene boundary sediments in the Perdue Hill Quarry. These samples produced an assemblage of approximately 20 species. The most abundant genera include; Bulimina, Uvigerina, Cibicides, Siphonia, Nonion, and Nodosaria. The Eocene assemblage is dominated by Bulimina and Uvigerina. The Oligocene assemblage is dominated by Cibicides, Siphonia, Nonion, and Nodasaria. This change in Benthic Foraminiferal Assemblages across the Eocene-Oligocene Boundary is interpreted to indicate a shift in environmental conditions. The most likely change is a decrease in water depth associated with Late Eocene eustatic sea level fall. The change in Benthic Foraminiferal assemblage correlates well with the planktonic Foraminiferal biostratigraphic zonation from this section, which indicates the Eocene-Oligocene boundary is located in the same position as the changes in Benthic assemblage composition.