Digital Surfaces and Thicknesses of Selected Hydrogeologic Units of the Floridan Aquifer System in Florida and Parts of 
Georgia, Alabama, and South Carolina

By Lester J. Williams and Joann F. Dixon

Groundwater Resources Program

USGS Data Series Report 2015-926

http://pubs.usgs.gov/ds/0926/
http://dx.doi.org/10.3133/ds926

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Abstract

Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system were developed 
to define an updated hydrogeologic framework as part of the U.S. Geological Survey Groundwater Resources Program. 
The dataset contains structural surfaces depicting the top and base of the aquifer system, its major and minor 
hydrogeologic units and zones, geophysical marker horizons, and the altitude of the 10,000-milligram-per-liter 
total dissolved solids boundary that defines the approximate fresh and saline parts of the aquifer system. The 
thicknesses of selected major and minor units or zones were determined by interpolating points of known thickness 
or from raster surface subtraction of the structural surfaces. Additional data contained include clipping polygons; 
regional polygon features that represent geologic or hydrogeologic aspects of the aquifers and the minor units or 
zones; data points used in the interpolation; and polygon and line features that represent faults, boundaries, and 
other features in the aquifer system.


The digital datasets are downloadable as individual zip files contained within the download directory:

Geodatabase
ds926.gdb.zip - Layers are arranged in the geodatabase by figure number, plate number, and thicknesses. 
Two additional feature classes, basemap and other_features, containing layers pertaining to the feature classes.

Shapefiles
ds926_shapefiles.zip - Contains all point and vector based data arranged by figure number, plate number, 
and thicknesses. Two additional directories, basemap and other_features, containing shapefiles pertaining to the 
directory name.

ASCII rasters
ds926_ASCII_rasters.zip - Contains all raster data listed in the geodatabase in ASCII format arranged 
by figure number, plate number, and thicknesses.



Suggested Citation
Williams and Dixon, 2015, Digital Surfaces and Thicknesses of Selected Hydrogeologic Units of the Floridan Aquifer System 
in Florida and Parts of Georgia, Alabama, and South Carolina: U.S. Geological Survey Data Series 926, available online at 
http://pubs.usgs.gov/ds/0926/ or http://dx.doi.org/10.3133/ds926

Companion Report
Williams and Kuniansky, 2015, Revised Hydrogeologic Framework of the Floridan aquifer system in Florida and Parts of Georgia, 
Alabama, and South Carolina, U.S. Geological Survey Professional Paper 1807. Report available from: http://pubs.usgs.gov/pp/1807/ 
or http://dx.doi.org/10.3133/pp1807