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Coastal & Marine Geology Program > Center for Coastal & Regional Marine Studies > Geologic Characterization of Lakes and Rivers of Northeast Florida > OFR 00-180

Subsurface Characterization of Selected Water Bodies in the St Johns River Water Management District, Northeast Florida

Northeast Florida Lakes and Rivers Home
North East Florida Atlas
About the Atlas:
Introduction You are at the introduciton to the NE Florida Atlas
Methods
Regional Geology
Karst Development & Characterization
Sinkhole Lake Evolution & Effect of Urbanization
Identification of Karst Features from Seismic Patterns
Summary
Acknowledgements
References
Printable Version of the Atlas
Contacts
About the Atlas

Introduction

Location of lakes and rivers in northeast Florida from which high-resolution single-channel seismic profile data were collected.
Figure 1: Location of lakes and rivers in northeast Florida from which high-resolution single-channel seismic profile data were collected. Click on the image for a larger version.
Florida is a karst (limestone) platform with abundant sinkholes, springs, and caverns. Karstic erosion of the land surface is controlled by chemical and mechanical processes occurring in the upper portion of the limestone where the most intense dissolution occurs (Beck, 1988). In Florida, surface features characteristic of karst include dolines (sinkholes), solution pipes, broad flat-bottomed prairies and closed circular depressions that either drain underground or fill with water to form lakes.

The term "sinkhole," or doline, implies a form, a function, and a basic mechanism of origin (Waltham, 1989). The form is a closed basin having no surface drainage outlet. The function is to transmit surface water underground to an aquifer or discharge ground water to the surface as a spring. Sinkhole origin is initiated by solution of the underlying host rock. Sinkholes form primarily on terrain of limestone or dolomite, or where either of these rocks occur near from the surface. They can, however, form over any rock that is soluble.

Surveys of sinkholes were conducted in part to test the effectiveness of shallow-water marine geophysical techniques in determining the geomorphology of karst features. Investigation of subsurface karst features has proven to be a difficult task. Due to their random, unpredictable distribution, natural cavities or buried sinkholes are notoriously difficult and expensive to locate and assess in site studies. There are several direct and indirect methods of mapping and identifying features associated with karst, all of which have limitations. Waltham (1989) provides a review of the methods used for the detection of cavities. Methods of geophysical applications used in cave and sinkhole detection have been reviewed by Bates (1973), McCann and others (1982), Owen (1983), and McCann and others (1987). These authors, however, report that previously applied geophysical techniques had little reliability for widespread use, but the potential cost savings compared to other methods warrant consideration. High-resolution seismic-reflection profiling (HRSP) been used to detect subsurface features related to karst in lakes and rivers with varying degrees (Missimer and Gardner, 1976; Locker and others, 1988; Snyder and others, 1989; Sacks and others, 1991; Subsurface Detection Inc., 1992; Kindinger and others, 1994, 1996, 1998, 1999) and also offshore in the Atlantic Ocean (Meisburger and Field, 1976; Popenoe and others, 1984; Snyder and others, 1989).

Cooperative investigations of north central Florida lakes and rivers were conducted from 1993 to 1996 by the St. Johns River Water Management District (SJRWMD) and the US Geological Survey (USGS) (Fig. 1). This report presents the data from recently developed digital High Resolution Seismic Profiling (HRSP) and identifies subbottom features from selected lakes in Florida. The objectives were: (1) identify evidence of breaches or discontinuities of the confining units between surficial water bodies and the Floridan aquifer, and (2) identify diagnostic features, structure, and geomorphology of sinkhole lakes.

Coastal & Marine Geology Program > Center for Coastal & Regional Marine Studies > Geologic Characterization of Lakes and Rivers of Northeast Florida > OFR 00-180

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