Paleontology and geology
A warm, tropical sea periodically flooded southern Mississippi during the Tertiary. Fossils of molluscs, whales, sharks, bony fish, and dugongs (relatives of manatees) can be found in these marine sediments. The northern part of the state was above sea level. The landscape was dominated by large rivers, swamps, and forests. The remains of one of these forests can be seen by visiting the Mississippi Petrified Forest, located about twenty miles northwest of Jackson.