STRUCTURAL WORK DURING 1901 AND 1902 IN THE EASTERN 
OHIO OIL FIELDS. 
By W. T. Griswold. 
INTRODUCTION. 
In the latter part of the field season of 1901 the writer undertook 
the investigation of two important economie problems relating to the 
accumulation of oil, the field work being continued during 1902. The 
problems noted were, first, the determination of the degree of accu 
racy with which a stratum at considerable depth can be plotted under 
favorable conditions, viz, easily distinguished outcropping strata and 
high degree of accurac} 7 in topographic and geologic work, and, second, 
the effect of geologic structure on the accumulation of oil and gas. 
FACTORS CONTROLLING ACCUMULATION OF OIL. 
Structure. — The theory that the accumulation of oil and gas is con- 
trolled by the geologic structure of the porous strata in which it is 
contained has been advanced by Prof. I. C. White, and discussed by 
many leading geologists under the general designation of the anti- 
clinal theory. 
The anticlinal theory ascribes the accumulation of oil and gas in 
pools of economic value to the influence of geologic structure. The 
oil and gas are supposed originally to have been widely disseminated 
throughout the sedimentary deposits in which they were formed, and 
their segregation is thought to be due to the different specific gravi- 
ties of the various fluids occurring in the rocks. If a porous stratum 
contains gas, oil, and water, these fluids will arrange themselves 
according to their specific gravities, and if this stratum is not hori 
zontal the lighter fluids will be forced toward the higher part of the 
stratum until their progress is stopped by change in structure or other 
conditions. In this case an accumulation of gas and oil will be formed 
that may be of sufficient quantity to be of economic value. 
This theory is now generally accepted by leading geologists. Unfor- 
tunately, however, only a small percentage of the men actually 
engaged in the production of oil attach much value to any geologic 
theory. This is probably owing to the fact that the method of repre- 
senting geologic structure by contours has not been previously applied 
336 
