|
 |
|
|
 |
Open File Report:
Seismic Reflection
Surveys |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
Drayton Island |
 |
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
| |
Location
of seismic profiles collected from the vicinity
of Drayton Island in Lake George. Click on the number in red
to view Figure 33. |
In February, 1994, reconnaissance profiles were run from the vicinity
of Drayton Island that is situated in the confluence of the St. Johns River
and Lake George in Putnam county (Fig. 3) to Palatka. These surveys
were conducted to test data acquisition in the St. Johns River for future
more detailed work.
An example of this data from the northern portion
of Lake George (Fig. 10) is shown in Figure 33. This is an example of a
deep buried subsidence sinkhole. Reflections are resolvable at depths of
44 milliseconds (37 meters, 120 feet) at this site and even deeper in others.
The surveys provided excellent detail of cross bedding in the river channel
and identified other buried sinkholes along the channel. Resolution was
poor in areas where bottom conditions caused multiples and post processing
did little to enhance the data. Further work is being done to assess the
data for previously mapped faults, structure and morphology of the Croaker
Hole near Welaka and correlation to available borehole geophysical data.
top of page
 |
next section
|
