The Maria fold and thrust belt (MFTB) is a portion of the North American Cordillera orogen in which geological structures accommodate roughly north–south to northwest-southeast vergent Mesozoic age crustal shortening. This lies in contrast to the remainder of the Cordillera, in which shortening is predominantly east–west. Structures associated with the Maria Fold and Thrust Belt are exposed in a series of mountain ranges in southeastern California and western Arizona. Many of the deep structures of the MFTB have been exposed due to east–west to northeast-southwest Cenozoic age extension and unroofing.