GLOBAL EXPANSION AND PALEOMAGNETIC DATA

Abstract

The method for detecting changes in the earth’s radius from paleomagnetic data, as originally proposed by Ward (1963) is reviewed and, slightly modified, applied to the available observations. The method enables us to calculate the paleomagnetic pole positions for different radii of the earth: the earth’s radius for which the coeval poles of one continent show the least scatter is considered the best estimate of the radius during that geological period. A number of paleomagnetic observations appear to be suitable. They suggest that the Permian radius of the earth was about 0.8 of the present one. In Cretaceous time this ratio had increased to 0.9’7-0.98. For the rest of the paleomagnetic observations the method does not work, as they indicate neither a changing nor a constant earth’s radius. It is probable that these latter observations lack the accuracy required for this kind of investigation.