American Cordillera
This north–south shortening is anomalous, as crustal shortening in the rest of the North American Cordillera is oriented generally east–west because of the generally east–west compression that was due to the subduction of the Farallon plate under western North America. Also unlike the rest of the North American Cordillera, deformation in the MFTB involved rocks of the North American Craton, most notably the Grand Canyon sequence of sedimentary rocks.