48 G. H. WESTBY 
pated from the seismograph work. The reflection results were re- 
checked and found to be satisfactory. It was concluded that the geo- 
logical assumption of uniform dip between seismic datum points was 
in error. Further seismic work confirmed this belief and resulted in the 
map C shown in Fig. 3. A well was located in the SE. SE. SE. Sec. 28 
and was drilled to the Wilcox. The seismic work was checked per- 
fectly and as this is being written the well has just commenced to 
make a considerable amount of gas and oil from the Wilcox sand. 
TOPOGRAPHY AND GEOLOGY 
The topographic relief in the area shot is about 50 feet or about 
equal to the structural closure. The creek shown on map D in Fig. 
4 has a flood plain averaging one-third mile in width over the pros- 
pect. 
The Checkerboard limestone outcrops to the northeast and west 
of the prospect. It was found also in a few shot holes. Its position in 
these shallow holes indicates a nosing over the north end of the pros- 
pect. Out of the alluvium filled flood plain Pennsylvanian shales are 
found beneath a thin mantle of soil. 
The Glenn sand, here water bearing, lies at about 1,800 feet. The 
Taneha sand containing oil and gas occurs at a depth of 2,050 feet. 
The Wilcox sand is the chief source of production in this area. Its 
average yield is about 5,000 barrels to the acre but on good structures 
this average has exceeded 30,000 barrels per acre. A partial section 
of the lower formations is shown in Fig. 5. Over the top of the struc- 
ture thinning in the Mississippi lime permits accentuation of structure 
in the Wilcox sand. 
EQUIPMENT AND METHODS USED IN SEISMIC WORK 
SHOWN ON MAP BIN FIG. 2 
A standard Seismograph Service Corporation crew was employed. 
Six electro-magnetic pickups were used, each connected through a 
three stage amplifier. Recording was accomplished by a moving coil 
oscillograph. Timing lines of one one-hundredth second were placed 
on the record by means of a tuned light shutter controlled by a tuning 
fork. Telephone communication by means of a line from shot point 
to recorder transmitted the shot moment and instructions from the 
observer to the shooter. An example of records taken with this equip- 
ment is shown in Fig. 6. 
Shot holes were dug to the base of the alluvium or to a similar 
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