PETROLEUM RESOURCES—LEVORSEN 
follows. The data used are all taken 
from geologic articles and publications 
available to everyone, much of it in 
the publications of our Geological 
Society. It is the purpose here to 
give some indication of the enormous 
volumes of rocks favorable to petrol- 
eum production but which are as yet 
essentially unexplored. Some of these 
areas and ideas are highly speculative 
at this time, but experience has shown 
over and over again that every produc- 
ing area, whether an individual field 
or a great province, was at one time in 
a similar speculative position. 
The areas selected are shown on the 
North American base map, figure 2. 
They are: (1) the overthrust fault 
belts; (2) the plains regions of western 
Canada and Alaska and of eastern 
Mexico and Guatemala; and (3) the 
wedge out of Lower Cretaceous and 
Jurassic sediments in the Southeastern 
States. 
(1) Overthrust fault belts—More than 
2,500 linear miles from 5 to 100 miles 
wide are shown on the base map in 
which older rocks are thrust over 
younger rocks and in which the geo- 
logy is so complicated as to make it 
extremely difficult to map and under- 
stand. Interpretation of geophysical 
measurements in these fault areas is 
generally impossible. The correct 
knowledge of the geology appears to 
lie in better and more accurate surface 
mapping coupled with careful records 
of deep wells. Probably of equal im- 
portance is the need for geologists to 
learn more of the nature and mechan- 
ics of faulting. 
Yet, within these overthrust belts, 
evidence of petroleum has been found 
at many places, and several oil fields 
discovered. One of these belts ex- 
tends from British Columbia and 
Alberta south across western Mon- 
tana and Wyoming and into Utah 
and Nevada. The Turner Valley 
pool of Alberta (fig. 3) is located in it. 
Another belt is located in the western 
Ouachita Mountains of Oklahoma 
and probably extends southwest across 
Texas. The South Mountain pool 
817369—49——19 
247 
(fig. 4) is one of several examples of 
oil pools in the Ventura region of 
California characterized by thrust 
faulting. The third belt is in the 
Appalachian Mountains extending 
from New York into Alabama where 
it passes under the overlapping Cre- 
taceous and Tertiary rocks. The re- 
cently discovered Rose Hill pool (fig. 
5) in Virginia occurs in this belt. 
Apparently thrust faulting and the 
sort of deformation which occurs in 
these belts are not detrimental to the 
occurrence of petroleum. 
One factor which makes these belts 
favorable for petroleum accumulation 
is the fact that they are generally 
located over areas in which the sedi- 
ments increase rapidly in thickness, 
often thickening at a rate of hundreds 
of feet to the mile. Wherever sedi- 
ments thicken, we may expect to find 
wedge belts of porosity and permea- 
bility, a phenomenon common to 
many proven oil-bearing provinces. 
Since the belts of expanding sediments 
antedate the faulting, they thus pro- 
vide a regional trap before the faulting 
occurred. In fact, they may have also 
localized the thrusting over the initial 
dips which prevailed. 
The Choctaw and related over- 
thrust faults in the western part of the 
Ouachita Mountains of Oklahoma 
(fig. 6) deserve special attention as one 
example of the scale of trap we may 
expect to find in these overthrust belts. 
Here the Ouachita facies of Paleozoic 
age are thrust northwest out and over 
the buried Arbuckle rock facies along 
a front 50 to 100 miles in length. The 
surface maps of this part of Oklahoma 
show the faulted area as separating the 
Lehigh Basin to the northwest from 
the Prairie Hollow syncline to the 
southeast, in each of which the rocks 
are dropped down nearly 2 miles. 
The map and cross sections recently 
published by Hendricks of the United 
States Geological Survey are the basis 
of the section (fig. 7). Below the 
Choctaw overthrust fault, a large anti- 
cline is shown in the older Paleozoic 
formations of the Arbuckle facies, 
