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Geologic Map of the State of Florida
[This text is taken from the Florida Geological Survey Open File Report No. 80.]
The basement rocks of the Florida Platform include Precambrian-Cambrian igneous rocks, Ordovician-Devonian Sedimentary rocks, and Triassic-Jurassic volcanic rocks (Arthur, 1988). Florida's igneous and sedimentary foundation separated from what is now the African Plat when the super-continent Pangea rifted apart in the Triassic (pre-Middle Jurassic?) and sutured to the North American craton (Smith, 1982).
A thick sequence of mid-Jurassic to Holocence sediments (unlithified to well lithified) lies unconformably upon the eroded surface of the basement rocks. Carbonate sedimentation predominate from mid-Jurassic until at least mid-Oligocene on most of the Florida platform. In response to renewed uplift and erosion in the Appalachian highlands to the north and sea-level fluctuations, siliciclastic sediments began to encroach upon the carbonate-depositing environments of the Florida Platform. Deposition of siliciclastic-bearing carbonates and siliciclastic sediments predominated from mid-Oligocene to the Holocene over much of the platform. Numerous disconformities that formed in response to nondeposition and erosion resulting from sea-level fluctuations occur within the stratigraphic section.
The oldest sediments exposed at the modern land surface are Middle Eocene carbonates of the Avon Park Formation which crop out on the crest of the Ocala Platform in west-central Florida. The pattern of exposures of younger sediments is obvious on the geologic map. Much of the state is blanketed by Pliocene to Holocene siliciclastic-bearing sediments that were deposited in response to late Tertiary and Quaternary sea-level fluctuations .
The characteristic landscape of Florida is relatively to extremely flat. There are few large, natural exposures and limited smaller exposures that geologists can investigate. The result is that geologists must rely primarily on de-watered or dry pits and quarries for exposures and must make use of subsurface data in studying the geology of Florida. Subsurface data, in the form of well cuttings and cores, were utilized extensively in the development of this map. Formational tops recognized in the subsurface have been extrapolated to the surface where exposures are limited.
Florida Geological Survey
By Thomas M. Scott, P.G. 99
U.S. Department of the Interior, U.S. Geological Survey
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Last updated: 04 September, 2013 @ 02:03 PM(TJE)