FLORIDA GEOLOGICAL SURVEY


resources. Thirty-four cross sections have been
produced for this study (Plate 1). Each of the
cross sections illustrates regional
lithostratigraphy of Eocene through Pliocene
formations, lithology, mineralogy, gamma-ray
logs, topographic profiles and hydrostratigraphic
delineations. Although most of the data used to
construct the cross sections was taken from
wells drilled as part of ROMP (Gomberg, 1975),
borehole data (e.g., from cores, cuttings and
geophysical logs) from the FDEP-FGS and the
U.S. Geological Survey (USGS) were utilized to
fill in as many gaps as possible.

 The mapping phase of the study facilitated
development of a new geologic and
hydrogeologic database, FGS Wells. Structure
contour (surface elevations) and isopach
(thickness) maps for all regionally extensive
lithostratigraphic and hydrostratigraphic units
within the District were then developed. The
maps include all units between land surface and
the top of the Middle Floridan confining unit
(Table 1).

 Data from more than 1050 wells (including
offshore boreholes) serve as control for these
maps (Plate 2). In addition, synthetic wells were
used to provide lateral (edge) control during map
surface interpolation. These wells represent an
artificial stratigraphic record for a given location
based on interpolated elevations from existing
maps or cross sections. The new surface and
thickness maps presented herein were developed
using the ESRI geographic information system
(GIS) program ArcMAP (see Map Development
and Data Management, p. 24) for details on map
production. Each map includes the lateral extent
of each unit and locations of wells within the
study area that were used to interpolate surfaces
and thicknesses.

Study Area

 Maps and cross sections produced for this
study cover the entire SWFWMD region (Figure
1). To facilitate present and future hydrologic
modeling and comparison of these maps to
adjacent Water Management Districts, a 10 mi
(16.1 km) wide buffer extending beyond the
District boundary was included in the study area


(Figure 1, Plate 2). Surface interpolation
techniques, such as kriging, can produce non-
representative contours along the margins of
mapped units. To address these undesirable
"edge effects," data from within a second 10 mi
(16.1 km) wide buffer zone was utilized. The
additional data helped stabilize surface
interpolations and contours, and allowed for a
more accurate delineation of the vertical and
lateral extents of certain mapped units. The
project study area, which covers approximately
14,340 mi2 (37,141 km2), does not include
wells within the second (outermost) buffer.

Previous Investigations

 Numerous researchers have focused on the
regional geology and hydrogeology of southwest
Florida. Sub-Floridan aquifer system geology,
with an emphasis on pre-Cenozoic basement
geology, is presented in several papers including
Applin (1951), Applin and Applin (1965), Bass
(1969), Barnett (1975), Smith (1982) and
Chowns and Williams (1983). Arthur (1988)
and Heatherington and Mueller (1997) focus on
geochemistry of basement terrains, while Smith
and Lord (1997) summarize the tectonic and
geophysical aspects of the Florida basement.
Gohn (1988) and Randazzo (1997) provide
comprehensive overviews of Mesozoic and
Cenozoic geology of the Atlantic Coastal Plain,
including peninsular Florida. Mesozoic and
Cenozoic paleoceanographic and structural
evolution along the margin of the Florida
peninsula is presented in Hine (1997).

 Selected early studies of Cenozoic and
younger formations include Applin and Applin
(1944), Cooke (1945), Puri and Vernon, (1964)
and Chen (1965). More recent stratigraphic
research on units in south and southwest Florida
has been completed by Miller (1986), Scott
(1988), McCarten et al. (1995), Brewster-
Wingard et al. (1997) and Cunningham et al.
(1998). Missimer (2002) focused on Oligocene
through Pliocene stratigraphic relationships in
the southernmost part of the present study area
(Charlotte County), as well as Lee and western
Collier Counties. Pliocene and younger
stratigraphy has been the focus of several studies