Abstract

This complex subject has had no definite factor to which it might be tied. The author suggests that a structural concept expressed in previous papers in connection with exploration for oil may be such a tie. In this concept the occurrence of fundamental northeast-southwest and northwest-southeast trends of deformation are described, which are believed to be the results of zonal pressures parallel to the earth's equator which occurred at the time the first condensation of the crust took place and the continents were formed as segments in these zones. If so, continental drift, including particularly the rotational movement involved, could not have occurred except by rotations of 90°, 180°, or 360°, or by following zigzag courses with 90° turns and no rotation.

As geophysical data on the interior of the earth increase, their interpretation tends to bring out more clearly the highly irregular nature of the Mohorovicic discontinuity. It has been reported from Russia that structure on this surface has been found to reflect generally the regional and local structure at the surface, where it has a northwest-southwest trend. This indicates that the continental crust either extended through the M discontinuity at the time the fundamental trends were formed or that this deformation extended downward as the continental crust thickened. Both possibilities suggest a stable continent, although the mechanism suggested by Dietz probably could apply.

In connection with the occurrence of materials which are interpreted as being evidence of ancient glacial conditions associated with continental drift, it is suggested that these deposits may have been associated with high altitudes. For instance, the Ouachita Mountains of southeastern Oklahoma once probably formed high ranges; as others have pointed out, the erratics of the region may have been derived from mountain glaciation on these ranges and have been ice rafted into the flysch of Johns Valley. Surely glaciation in the Himalayas and Andes is causing widespread deposition and markings that in time could be taken as evidence of continental glaciation.

To counteract the evidence of paleomagnetic data that continental drift has occurred requires showing that the geomagnetic and geographic axes need not approach coincidence. Evidence is increasing that the earth's core is liquid and that a mechanism exists associated with it which does not require this coincidence.

In connection with the origin of oil, it has recently been proposed that pre-Tertiary oil fields have paleolatitudes of less than 20° and that, therefore, drilling for Paleozoic and Mesozoic oil should be preceded by paleolatitude studies. This theory is further tied up with the concept of the continental origin of hydrocarbons which has been expressed as the official view of the Soviet Academy of Science.