Drillers looking to help produce drinking water for Pine Island residents have dug up evidence that Florida, the self-proclaimed 'Sunshine State', may be a lot older than we thought. In a new study of mud and rock samples, drilled from a 700m salt-water injection bore-hole, the University of Florida has described the area around Fort Myers as similar to the islands of the Florida Keys today. Until now, geologists had thought that Florida was inundated under a shallow sea, until at least 35 million years ago, during the Oligocene epoch.
With the discovery of several thick brown lignite deposits, soft coal-like rocks rich in plant matter, the advent of land has been pushed back to some 45 million years ago - to a time known as the Eocene epoch. These deposits were analyzed by David Jarzen, research scientist for the Florida Museum of Natural History.
From his analysis of the pollen and plant remains found, it is thought the area was a boggy swampland, bordered by warm seas. Trees, palms, ferns and herbs are all likely to have flourished in a series of low-lying islands.
The study was published in the current issue of Palynology, and dated the sediments using the remains of small-marine animals, known as foramnifera. These were found in limestone layers between the lignites. Co-author Curtis Klug described the process of sampling ''As we're drilling through the rock and the cuttings come to the surface, we collect them, examine them, and determine the type of rock and its estimated age''. The foramnifera are single-celled marine animals for which there is a well-used dating mechanism.
Modern-day Floridans would likely feel at home. Georgia Southern University professor of geology, Fredrick Rich, says ''Those terrestrial trees, shrubs and herbs didn't live out there all by themselves. I envision a small key, or maybe several small keys just like the islands in Florida Bay.''
The study will also aid future drillers seeking to make the best use of Florida's water resources. It shows that the underlying geology is more complex than thought. Rich said. ''There is a buried landscape down there and the engineers need to know that is the case.''