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WELCOME TO FLORIDA
AND THE GEOLOGY OF THE FLORIDA PLATFORM
The State of Florida represents the exposed portion of a broad carbonate buildup known as the Florida Platform. This platform extends westward under the Gulf of Mexico a couple of hundred miles, making the west coast of the Florida Peninsula the approximate center line of the feature. While our surface relief is minor compared to mountainous areas of the earth, our subsurface geology and geomorphology, shaped by marine and surficial processes, is highly complex and offers great interpretative challenges to our geoscience professionals. We typically don’t have the luxury of observing miles of outcrops along railroad or highway cuts through mountains or hills to aid in our geologic mapping solutions. The majority of our data comes from subsurface cores, well cuttings, wireline geophysical logs, surface geophysics and water geochemistry. This requires significant skill among our State’s geologists to interpolate between known data points, to understand hydrogeochemical processes, and to predict subsurface conditions in areas with little information.
Beneath the thousands of feet of limestones, dolostones, and evaporates that comprise the bulk of the stratigraphic sequence beneath our state; Florida’s basement rocks include Precambrian-Cambrian igneous rocks, Ordovician-Devonian sedimentary rocks, and Triassic-Jurassic volcanic rocks. These range in depth from just under 3,500 feet in the north central peninsula to over 18,000 feet in south Florida. Overlying this basement sequence is the thick accumulation of shallow marine carbonates, reflecting the region’s separation from what is now the African Plate when the super-continent Pangea rifted apart in the Triassic – Early Jurassic. The shallow seas flooding into the rifting basin began the long sequence of carbonate buildup we see today as the foundation of the Florida Platform. By the Late Oligocene, the clastic sediments eroding from the southern end of the Appalachian Mountains began to reach the pristine shallow marine environments of the Florida Platform. Throughout the Neogene fluvial, coastal, and shallow marine systems transported clastics onto the platform. Numerous sea-level fluctuations subsequently eroded, redeposited and reworked these sediment packages throughout the area. Superimposed on this complex sequence of migrating coastal environments, are the multifaceted episodes of subsurface and surface karstification that became the precursor for the world-class Floridan Aquifer System. Stratigraphic changes, lithofacies shifts, bedding sequences, joints, fractures, faults, caves, sinkholes, and springs all combine to make our prediction of subsurface fluid movement challenging to say the least. Clearly, simple “engineering” solutions for contamination clean-up based on standardized models are doomed to fail without competent professional geology being a part of the assessment.
Florida’s distinctive geologic history, paleoenvironments, and post-depositional modifications of our geologic units have led to many unique and significant economic mineral deposits. Florida was recently ranked 5th in the Nation with a combined estimated mineral production of $1.75 billion. Our state supplies about one-quarter of the world’s phosphate needs and three-quarters of US domestic needs. Florida ranked second nationally in production and fourth in consumption of crushed stone (limestone and dolostones), and we are in the top five in the production of Portland cement and peat; and first in the production of masonry cement. We rank 15th in sand and gravel used or produced, and continue to lead the nation in heavy minerals and fuller’s earth production. Florida also produces significant amounts of kaolin, common clay, sand, fill clay, and shell. Florida also produces Oil & Gas from the Cretaceous Sunniland trend in South Florida and from the Jurassic Smackover in NW Florida, near Jay. Dimension stone is no longer produced in Florida, however historically it was mined in the panhandle and on the east coast. Hard-rock phosphate also is no longer mined.
Florida’s Professional Geologist community is a diverse and active group of professionals. Their professional contributions are mostly involved in various hydrogeologic aspects of land-use decisions or for permit support (municipal well supply, landfills, contamination assessment and remediation, aquifer recharge mapping, injection wells, aquifer storage & recovery wells, etc.). Other areas include: economic geology (mining), coastal erosion / flood control assessments, environmental consulting, with local and state governmental agencies, and as professional colleagues within engineering firms.
Florida is mostly known as a tourist state. We are famous for our beaches, weather, coral reefs, springs, lakes, and commercial attractions. We are also strong in the agricultural arena with large parcels dedicated to citrus, vegetables, and other farm products. But generally, economic minerals or a need for competent professional geology to assist with natural resources conservation or environmental sustainability is not typically a visible component when various issues of importance to the pubic are discussed by our policy makers. Nevertheless, our state, located between the Gulf of Mexico and the Atlantic Ocean, our abundant springs, lakes, and wetlands, our vast amounts and dependence on groundwater, and our substantial amount of annual rainfall, make our peninsula a natural “hydrogeologic engine” as these processes continually modify and shape our water dominated physiography, and support our ecosystems and unique environments. Florida has much to offer and challenge our geoscientists and interested geology students. It’s great to live and work in paradise.
Walt
Schmidt, Ph.D., P.G.
State Geologist & Chief
Florida Geological Survey
Gunter Building
903 W. Tennessee St.
Tallahassee, Florida
32304-7700
DEP MS #720
850/488-4191 voice
850/488-8086 fax
e-mail: walt.schmidt@dep.state.fl.us
FGS Web page: http://www.dep.state.fl.us/geology/
