160 C. A. HEILAND 
of gas from the productive layers into the upper strata, which has 
been previously mentioned, has replaced all salt water and has made 
the strata poor conductors. At what depth this zone begins would be 
difficult to state as the curves are not complete enough to draw such 
conclusions. If this assumption is correct, it follows that the electrical 
characteristics of the Wealden can not be much different from those 
of the Dogger, as the curve observed in the northwest profile in the 
east is not much different from the curve observed in the west trav- 
erse. It actually appears from geologic reports that the Wealden is 
also oil bearing in this area and contains a heavy oil which is not 
exploited, and it is further seen from the results that, if such an oil 
horizon exists below the locality of the northwest part of the east 
profile, this horizon is at shallower depth at this point than it is in the 
west. The southwest part of the east traverse does not show an in- 
fluence of poor conductors at the depths reached. 
As a whole, the data published by Koenigsberger appear to be far 
too meager to permit very far-reaching conclusions. They do not seem 
to indicate that it would be possible with his method to differentiate 
a poorly conductive sedimentary stratum devoid of oil, from a 
stratum which is saturated with oil. It is possible that Koenigsberger 
has used greater electrode separations and thus greater depths of 
penetration in addition to those for which results have been published, 
and it is possible that the results obtained at greater depth sub- 
stantiate his statements. However, the published data do not cor- 
roborate them, and the writer doubts very much that, if the illustrated 
results had been obtained in areas in which the presence of oil was not 
known, anybody would have seen anything unusual about them. 
The second instance where a direct location of oil by a resistivity 
method has been described offers much more concrete information. 
The results in question were obtained on a site in Kentucky, the 
geology of which is shown in Figure 39 a. Lee’s partition method was 
used, and the curves obtained when going to either west or east of 
both stations 2 and 3 are illustrated in Figure 39 6. The depth of the 
oil zone from the surface was in this place, however, much less than 
the depth of the oil zone on which Koenigsberger did his work; it 
was only 250-300 feet, while the depth of the productive oil forma- 
tions in Koenigsberger’s experiments was about three times as great. 
The oil zone occurs in the form of an oil sand between wells 2 and 3. 
Actually, east from station 2, the observed resistivity values were 
greater than those on the west, and the converse holds for station 3; 
490 
