Since then Florida has had a long and placid history, most of it under warm waters where limestone deposits built up over millions of years. Almost every geologic unit on this map is very fine grained shale, mudstone, and limestone, but there are some sandy layers, especially in the north, and a couple of phosphate layers that are extensively mined by the chemical and fertilizer industries. No surface rock in Florida is older than Eocene, about 40 million years old.
In more recent times, Florida has been covered and uncovered many times by the sea as the ice-age polar caps released and withdrew water from the ocean. Each time, the waves carried sediments over the peninsula.
Florida is famous for sinkholes and caves that have formed in the limestone, and of course for its fine beaches and coral reefs. See a gallery of Florida geological attractions.
This map gives only a general impression of Florida's rocks, which are very poorly exposed and difficult to map. A recent map from the Florida Department of Environmental Protection is reproduced here in an 800x800 version (330KB) and a 1300x1300 version (500 KB). It shows many more rock units and gives a good idea of what you might find in a big building excavation or sinkhole. The largest versions of this map, which reach 5000 pixels, are available from the U.S. Geological Survey and the state of Florida.
More Florida resources on About.com:
About Jacksonville
About Miami
About Orlando
About Tampa Bay
Florida Travel
Florida Maps
Florida Geography, State Symbols & Facts
Florida Weather & Climate
Florida Campgrounds
Florida Scenic Roads
Florida Beaches
Florida Museums
Florida Archaeology
