During Eocene time the site of the boundary between the States of Mississippi and Alabama fell within the transition zone between the Mississippi embayment and the open Gulf of Mexico. That different types of deposition proceeded simultaneously within these two regions may be inferred from the different facies which deposits of the same age exhibit on opposite sides of the State line. In general, much clay and carbonaceous material were laid down in Mississippi, while shell marl, laminated sand, and limestone were being formed in Alabama. The purpose of this paper is to point out the equivalences of formations of different facies in the two States. The formations of different facies in the two States. The correlation adopted in shown in the following table, all the formation names in which have been previously used, except Kosciusko sandstone, a new name proposed for a member of the Lisbon formation.