The cold climate conifer forests of the north displaced broadleaved woodlands. Plants and animals were gradually pushed south to find a warmer climate. Florida became a refuge from the cold. Down here is where the Ice Age north met the subtropical south. Today in a cool wooded part of the Sunshine State, you can still see some of these northern refugees.

The valleys along the Apalachicola River are home to many species that were forced here in the Ice Age e and now remain far away from their populations further north, like the copperhead snake and an astonishing variety of amphibians.

During the Ice Age, Florida was crucial to the survival of many such mild-weather species. They couldn't have withstood the cold of north, and without this refuge, they would simply have become extinct. Another leftover, but one that arrived from the opposite direction.