Period: Paleogene to Neogene Epoch: Late Oligocene to Early Miocene Faunal stage: Chattian through Hemphillian ~23.03–5.33 mya, calculates to a period of 17.7 million years The Alum Bluff Group replaces the Hawthorn Group west of the Apalachicola River with occurrences in Bay, Calhoun, Holmes, Jackson, Liberty, Okaloosa, Walton, and Washington counties.

The coloration is from cream to olive gray with mottled reddish brown in the weathered sections.

The sands are soft and very fine to coarse with sporadic gravel while carbonate lenses are quite hard.

[1][2] The Alum Bluff Group are defined by the stratigraphic position and mollusks contained within.

The residuum includes Lower to Upper Miocene and younger weathered sediments.