OPEN FILE REPORT NO. 80


 Groundwork for a new geologic map of Florida began in the 1980s with a county-level
mapping effort as part of a statewide radon investigation. The county maps created for the radon
project were merged and modified to produce a new State map. The geologists from the Florida
Geological Survey (FGS) involved in the project included Jon Arthur, Ken Campbell, Joel
Duncan, Frank Rupert, and Tom Scott. Tom Missimer, Missimer International, Ft. Myers,
Florida was part of the mapping team for Charlotte and Lee Counties. Previous mapping
provided a basis for this project. Geologists involved in the preliminary mapping included
Paulette Bond, Richard Johnson, Ed Lane, Walt Schmidt and Bill Yon.

 METHODS
 Much of Florida is covered by a blanket of Pliocene to Holocene, undifferentiated
siliciclastics that range in thickness from less than one foot to greater than 100 feet. As a result,
in developing the criteria for producing this map, FGS geologists decided to map the first
recognizable lithostratigraphic unit occurring within 20 feet (6.1 meters) of the land surface. In
areas where highly karstic limestones underlie the undifferentiated siliciclastics, paleosinkholes
may be infilled with significantly thicker sequences of siliciclastics. If the shallowest
occurrences of the karstic carbonates were 20 feet (6.1 meters) or less below land surface, the
carbonate lithostratigraphic unit was mapped. If the carbonates lie more than 20 feet (6.1
meters) below land surface, an undifferentiated siliciclastic unit was mapped.
 Undifferentiated siliciclastic sediments occur in significant thickness (>20 feet [6.1
meters]) over much of the Gulf Coastal Lowlands (White, 1970; Scott, in preparation) and the
eastern part of the Florida peninsula. Where these sediments were mapped, efforts were made to
determine if beach-ridge or dune topography was present in order to subdivide the siliciclastic
sediments.
 Lithostratigraphic terminology applied in this mapping effort followed, with limited
changes, the lithostratigraphic framework delineated for the Gulf Coast Region chart from the
Correlation of Stratigraphic Units of North America Project (COSUNA) (Braunstein et al.,
1988). Although some of the units depicted on the COSUNA chart have a significant
biostratigraphic basis, the COSUNA chart represents the best effort to date to provide an
accurate stratigraphic framework for the Florida Platform and surrounding regions.
 A peer review of the geologic map and this text by members of the geologic community
outside the FGS was done by S. Upchurch, R. Portell, T. Missimer, J. Bryan, J. Vecchioli, A.
Tihansky, K. Cunningham, G. L. Barr and R. Spechler. The FGS greatly appreciates the efforts
of these geologists.
 FGS cartographers Jim Jones and Ted Kiper worked on the initial phase of this project.
CAD analyst Amy Graves assisted in the map preparation. Lou Cross and Peter Krafft from
Florida Resources and Environmental Analysis Center, Florida State University, finalized the
map in preparation for publication.

 STRATIGRAPHIC COLUMN AND CROSS SECTIONS
 Lithostratigraphic units expressed on the State geological map range from Middle Eocene
to Holocene. The stratigraphic column showing the lithostratigraphic units utilized on the map
delineates only the formations occurring at or near the surface (Figure 1). Table 1 lists the
stratigraphic units and provides a brief lithologic components list. Cross sections (Figures 2 and
3) were constructed utilizing cores and well cuttings from the FGS well cuttings and core
repository. By necessity, the cross sections show some lithostratigraphic units that do not crop