Magmatism, orogenic timing, and orogenic diachronism in the Cordillera from Mexico to Canada

The distinction between the largely intra-Cretaceous Sevier orogeny and largely post-Cretaceous Laramide orogeny in the Cordillera between Montana and New Mexico does not exist in the northern Rocky Mountains of Montana and Canada and in the Cordillera of Mexico. An explanation of this in terms of the tectonics of the region is proposed.