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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

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Regional Geology
Karst Development & Characterization
Sinkhole Lake Evolution & Effect of Urbanization
Identification of Karst Features from Seismic Patterns
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Lake Disston
Flagler County, Florida

Introduction | Subsurface Characterization

Subsurface Characterization

Lake Disston
Lake Disston. Black lines show profile locations.
Lake Disston is characterized by a variety of seismic reflections. These reflections are consistent throughout the lake and are represented by the colored lines in seismic profiles A-A' and B-B' below. The lines have been digitized and the depths to the reflections plotted as contour maps shown below. In the eastern part of the lake there is a large subsidence (> 1 km), obscured by noise in the record (A-A' and Contour Maps 1, 2, 3). The western part has several smaller, near surface and deeper depressions (types 2 and 3, B-B'). The deep subsurface relationship between this complex and the larger subsidence is uncertain. Seismic profile B-B' shows a deeper subsidence (type 3) with infilling by Hawthorn Group sediments that appear to have fracturing or dissolution type features that have distorted the overburden (B-B', yellow line). These features may provide conduits for surface water recharge of the aquifer. Except for near surface sediments, the strata has subsided. High frequency, horizontal reflections near the surface may represent more lacustrine type fill, with no apparent disturbance (right green line).

Seismic Profile A-A'
Prolfile A-A'

Seismic Profile B-B'
Profile B-B'

Subsurface Profile C-C' Depth to Limstone
Subsurface Profile Depth to Limestone
Depth to Intermediate Horizon Depth to Lake Bottom
Depth to Intermediate Horizon Lake Disston Distribution of Features
(noted from seismic profiles)

Logs from wells in the area (Index Map D, wells V-0339, F-0296) show the depth to the Ocala Limestone to decrease from about -46 m (-150 ft) NVGD east of the lake to about -15 m (-50 ft) NGVD to the west. The reflective horizon represented by the dark green line in profiles A-A' and B-B', correlates with this contact. The variable relief of this horizon, as expressed on the left side of profile A-A', and in the contour plot (Depth to Limestone) and subsurface two dimensional profile C-C', is characteristic of mature karst development and a subsidence sinkhole. Besides the large depression in the east central portion of the lake (Depth to Limestone), there also appears to be dip in the karst surface to the northwestern portion of the lake. The plot of the intermediate horizon shows subsequent subsidence in the overlying Hawthorn Group sediments.

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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Updated December 05, 2016 @ 11:25 AM (JSS)