Neogene units lie near the surface in the Florida panhandle in a narrow band extending from 20 miles west of Tallahassee, Leon County, northwest to Oak Grove in north-central Okaloosa County. These sediments are primarily clayey, sandy (quartz), shell beds exposed along a number of stream or river bluffs. Downdip towards the Gulf of Mexico these units thicken and change in lithologic character. Although subsurface units, these contemporaneous lithologic packages can be defined and mapped throughout the region using stratigraphic core tests, water-well cuttings, and geophysical well logs. The Bruce Creek Limestone and Intracoastal Formation are two units, predominantly subsurface, mapped from this area. It is also noted that the Chipola and Jackson Bluff formations are younger downdip in the subsurface than where they are exposed up dip. Pleistocene quartz sands, gravels, and massive silty clay beds are mapped in Gulf, Franklin, and southern Liberty counties. These units were deposited in brackish and fluvial environments as the Apalachicola delta system advanced to the south. The Neogene and Pleistocene sequence of sediments thickens and dips along a gently plunging 3.Xis that descends gulfward through central Gulf County. This thickened sequence of sediments is called the Apalachicola Embayment. The lithologic and faunal characteristics of the formations, from the Upper Eocene to the Pleistocene are, summarized. This information is then used to suggest paleoenvironments for the various units. A generalized paleoenvironmental sequence is postulated from the mid- Tertiary to Recent. Differing opinions on the nature and origin of the Apalachicola Embayment have been expressed by numerous geologists. By incorporating interpretations from the Neogene (this paper) with sequential structural contour maps from the Upper Cretaceous to the Lower Micoene (unpublished maps by May and Schmidt, 1974), and Jurassic mapping by Pontigo (1982), with the large volume of published literature on the area, a geologic history has been synthesized. The low feature (embayment) resulted from a graben which had its origin in Triassic to Early Jurassic time. This graben slowly filled with sediments until it ceased to exist as an embayment at the end of the Early Cretaceous. From Early Cretaceous through Early Eocene a "low" or depression occurred east of the Jurassic axis. During Early through latest Eocene the axis of this "low" shifted to the northwest until the Oligocene, when it was repositioned once again over the Jurassic axis. This Late Cretaceous- Tertiary feature is considered to be due to slow deposition in a current-swept strait similar to the present Florida Straits. During the Early and Middle Miocene, the strait apparently began to fill in as carbonates from the Florida platform on the southeast infringed on the shallow channel, and clastics from the northwest spilled over onto the shallow shelf. From the Late Miocene to Pleistocene the strait completely filled and the prograding coastal plain migrated over the area. The feature does not currently exist as a topographic low since the Apalachicola River Delta has prograded over the area.