ABSTRACT

Southeastern Alabama, where the clastic upper Eocene and lower Oligocene beds from the west grade into and interfinger with the equivalent limestone beds toward the east, is an area of deep weathering. Exposure are lacking except along the rivers and major streams, where complete unweathered geologic sections can be studied by means of a small boat. Study of these sections where the two lithosomes and their distinctive fossils mingle has resulted in a better understanding of the stratigraphic relationships and correlation of upper Eocene and lower Oligocene strata between Mississippi and Florida.

The Moodys Branch Formation can be divided into a lower and an upper member in southeastern Alabama, the lower member being the Periarchus lyelli Assemblage Zone. The lower member is correlated with the Inglis Formation in Florida and the upper member with the Williston Formation. The members of the Yazoo Clay can be traced eastward into southern Alabama, where they merge into the Crystal River Formation, the "Ocala Limestone" of early reports. The upper member of the Yazoo (Shubuta Clay Member) is correlated with the upper part of the Crystal River (Asterocyclina Assemblage Zone) exposed in the vicinity of Marianna, Florida. The Red Bluff Clay is correlated with the Bumpnose Limestone that overlies the Crystal River Formation in the Marianna area. Like the Bumpnose, it contains the guidefossil Lepidocyclina chaperi Lemoine and Douville in exposures near Perdue Hill, Alabama.