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Indian Lake
Volusia County, Florida
Introduction | Subsurface Characterization
Subsurface Characterization
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| Indian Lake. Black lines show profile locations. |
Indian Lake is characterized by two areas of subsidence within the lake. These areas are shown in the map at right. Seismic profiles A-A' and B-B' are oblique cross-sections across the two depressions. Seismic profile A-A' (below) shows a bi-directional view of the larger of the two subsidence areas, as the survey trackline turns and crosses the depression twice. The profile shows a strong reflective horizon (red) about 28 m (92 ft) below lake level (9 m, 29.5 ft above NGVD). This horizon is interpreted to be the top of the Ocala Limestone, as correlated elsewhere in the study area with gamma-log profiles. There appears to be an area of collapse within the Ocala, approximately 150 m (492 ft) wide, that has caused a concomitant subsidence in the overlying structure. Seismic profile B-B' (below) shows a smaller subsidence in the southern part of the lake. Some structure such as collapse-related faulting is better visualized in this record. Because of the lack of visible features within the collapsed areas, these profiles show characteristics similar to a type 1 interpretation as shown in the explanation on the Siesmic Track Map. In the uppermost part of the profiles, a relatively transparent signal characteristic of organic debris and sands (type 6) appear to be infilling the depressions. Contour plots of the lake bottom and lower horizon, digitized from the seismic profiles, are shown below. The cross section C-C' was generated from the digitized surfaces.
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| Profile A-A' |
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| Profile B-B' |
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| Above: Subsurface Profile Across Indian Lake |
| Below: Lake Keene and Smokehouse Distribution of Features (noted from seismic profiles). |
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| Areas of subsurface Collapse |
Bathymetry
(depth in meters) |
Depth to Ocala Limestone
(depth in meters) |
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U. S. Department of the Interior | U.S. Geological Survey
