North American Craton

The North American
Craton

Taken from: The Glossary of Geology (1980)

Craton = A part of the Earth's crust that has attained stability, and has been a little deformed for a prolonged period. As originally defined, cratons included parts of both continents and ocean basins, but modern knowledge of the ocean basins indicates that the existence of cratons there is unlikely, so the term is now restricted to continental areas. The extensive central cratons of the continents, including both shields and platforms, have been called hedreocratons. Parts of the more mature Phanerozoic fold belts have now achieved, or are approaching, a cratonic condition. Also spelled: Kraton. See also: thalassocraton. Syn: kratogen.

Executive Summary:

If you envision a "lazy susan turntable" on top of the primary tectonic plate. when forces are applied to the plate, the responding tremors cause shifting of the entire Craton which swivels on its axis. The earthquakes and other seismic results are most extreme where the Craton presses against the areas that it is pushing.

The North American Craton's axis point is New Madrid, MO.