Abstract

The regional structural grain of the North American Cordillera is approximately N 20°W (340°). A great number of more subtle structures within the Cordillera and the Interior Plains trend north-south or east-west. The Caroline Arch in Alberta trends east-west and displays a lineament pattern with symmetry about the north-south direction. The observation of a strong fracture pattern in north-south and east-west directions in the Cordillera, and less conspicuous in the Interior Plains and the observation of similar trends in other continents suggest the presence of a global fracture pattern, possibly caused by changes in the shape of the Earth. Measurement of the structural intensity over the Peace River Arch of Alberta and the extension of the Cordillera in east-west direction in the Lower Cretaceous, Tertiary and Recent time, all show a remarkable correlation with Steiner’s hypothesis of the relationship of the sun’s position relative to the galactic centre with the rythmic expansions and contractions of the Earth. Steiner’s model predicts the change from an expanding Earth to a contracting or stable Earth in Pennsylvanian time. The Peace River Arch continued rising from the Devonian to Pennsylvanian time, and was stable, or slightly subsiding from the Permian to the Cretaceous. Maximum fault movement with vertical throw up to 250 feet (76 m) occurred in Pennsylvanian time. Steiner’s predictions of an expanding Earth since the Lower Cretaceous appears to be supported by strong east-west extensions of the Cordillera in Lower Cretaceous, Tertiary and Recent time. Fracture data might support Continental drift of North America “en block” in a westerly to southwesterly direction. Drift to the south, along meridians due to some “pole-fleeing force”, can best explain east-west trending folds and north-south trending tensile fractures.