Cenezoic sediments underlie the entire southeastern part of the Coastal Plain south of the Cretaceous outcrop. The Paleocene series consists chiefly of marine clastic deposits in southwestern Alabama and the Panhandle of Florida, limestone in southeastern Alabama, and dolomite and anhydrite in Peninsular Florida. The Eocene series consists chiefly of marine clastics with limestone at the top. In Peninsular Florida the entire series ins non-clastic. The Oligocene series is predominantly limestone where present but is absent in eastern Georgia and the eastern and central part of Peninsular Florida. The Miocene series consists chiefly of marine clastic deposits. In Georgia and Florida the lower part is a marl which grades into a limestone in places. Post-Miocene deposits are chiefly clastics. The coastal terraces have a mantle of Pleistocene marine sand and the stream terraces a mantle of Pleistocene fluvial clastics. Pleistocene limestone is present in southern Florida. The thickness of Cenezoic deposits ranges from less than 2,000 feet in an area in the northern part of the Florida Peninsula to more than 5,500 feet in southwestern Alabama and in southern Florida.

The southeastern Coastal Plain includes parts of two distinct sedimentary provinces, one of marine clastic sediments in the eastern part of the northern Gulf Coast area, and another of marine non-clastic sediments, chiefly carbonates and anhydrite, in Peninsular Florida.