PETROLEUM RESOURCES—LEVORSEN 
strated. Folds of all degrees of inten- 
sity, coupled with unconformities, 
facies changes, rapid eastward thick- 
ening of all rocks in the geologic 
column from Cambrian to Pennsyl- 
vanian in age, and all sliced with great 
numbers of low-angle faults assure an 
almost unlimited number of traps 
ore 
Cleveland $ 
o Indianapolis 
251 
lineation is more nearly north and 
south and passes under the southwest- 
northeast trend of the later over- 
thrusting. Moreover, the number of 
faults and their intensity increase from 
northeast to southwest until the belt 
passes under the Cretaceous and Ter- 
tiary overlap in Alabama. The pat- 
ene 
APPALACHIAN -OVERTHRUST 
wh REGION 
Regional 
Dip-strike é Anticlinal axis. 
100 MILES 
Ficure 8.—Reference map of the eastern United States showing the Appalachian overthrust 
belt crossing obliquely an older regional pattern of folding. 
extending from Alabama to Penn- 
sylvania. 
An interesting speculation may be 
be made on the basis of the evidence 
indicated on the geologic map, shown 
in figure 8. It is rather evident from 
this map that the fault belt crosses 
obliquely an older pattern of folding 
shown by the anticlinal trends and the 
regional strike of the rocks. This older 
tern suggests a sort of pendulum fault 
movement from AB to AC, the rocks 
from the east overriding the western 
rocks a progressively increasing dis- 
tance from north to south. 
The underlying western rocks are 
known oil and gas producers and may 
extend far to the east below the soles 
of the overthrust series. Isopach and 
paleogeologic maps offer the means of 
