Hairpins and Superintervals

Abstract

The path of apparent polar wandering relative to North America has several sharp turning points or hairpins. These hairpins record rapid changes in the direction of motion of North America relative to the pole. The youngest of these hairpins (in the Cretaceous) corresponds approximately in time to a major "tectonic reorganization" suggested by Coney on other grounds. The older hairpins are also supposed to represent first-order tectonic breaks, and they are therefore used to divide post-Archean time into 5 superintervals. The diastrophic significance of these superintervals is briefly discussed.