22 FLORIDA GEOLOGICAL SURVEY-EIGHTH ANNUAL REPORT. 
OIL PROSPECTING. 
Prospecting for oil and gas has been carried on in Florida at 
intervals for many years and at the present time drillings are being 
made near Tallahassee, Chipley and Kissimmee. 
Oil and gas may occur in any rocks which are sufficiently porous 
to retain them, but are found in commercial quantities only where 
favorable structural conditions exist. There must in all cases be 
a capping of impervious rock to retain the oil so that it may not es¬ 
cape to the surface. Large quantities of oil probably are not found 
except where there are particularly favorable structural conditions. 
The simplest structure probably is an arch or upward fold in the 
rock. The oil and gas being lighter than water, rise to the top of 
the fold and are retained there by the overlying impervious stratum. 
This simple upward fold is known as an anticline, and the theory 
of the accumulation of oil in a fold of this kind is known as the 
anticlinal theory, which was first proposed in 1892 by Dr. I. C. 
White, State Geologist of West Virginia. Dome structure in rocks 
affords equally favorable conditions, and involves the same princi¬ 
ples, the oil rising in the porous stratum to the top of the dome. 
Rock strata dipping in one direction only, thus forming a mono¬ 
cline, may by slight alterations in the rate of dip produce basins or 
other structures which are capable of retaining oil. In fact any 
structural feature in the rocks which permits the storage of a quan¬ 
tity of oil may afford a commercial supply. 
Structure, however, is not the only requisite, and it is not to 
be assumed that where the structure is favorable, oil and gas are 
necessarily present. The origin of oil and gas is not fully under¬ 
stood. The theory that more nearly meets general acceptance than 
any other, perhaps, is that the oil and gas are derived from an or¬ 
ganic source, either animal or vegetable matter imbedded in the 
rocks of the earth. An alternate hypothesis is that of an inorganic 
origin, it being assumed that the oil and gas originate through chem¬ 
ical reactions which take place deep within the earth. In either 
case the oil and gas move upward and are collected where the con¬ 
ditions are favorable in the rocks above. It thus follows that struc¬ 
tural conditions favorable to the accumulation of oil may and fre¬ 
quently do exist without any oil being present. On the other hand, 
oil and gas probably form in the earth without having an opportu¬ 
nity, owing to lack of favorable structure, to accumulate in com¬ 
mercial quantities. 
