Paleontology and geologyDuring the Quaternary, sea level fluctuated widely as glaciers grew and melted in the northern part of North America. Thick, alternating layers of marine shells and freshwater marls now exposed along the Florida peninsula provide evidence of the rise and fall of sea level over the state at this time. These fluctuations, coupled with Florida’s low topography, caused major changes in the amount of exposed land area. As glaciers to the north grew larger, sea level dropped up to 125 meters below present level, and Florida’s shoreline expanded nearly 150 kilometers to the west. Vast savannas formed and were populated by large animals, such as mammoths, mastodons, horses, and bison. Today, fossils of some of these mammals are found in sediments on the sea floor in the Gulf of Mexico. During warmer interglacial times, sea level rose up to 45 meters above present sea level. Most of the state’s modern topography (e.g. rivers, lakes, barrier islands) formed during this time. |