Abstract

The Rocky Mountain system extends from the Liard River, British Columbia, to near Santa Fe, New Mexico, and contains within itself a wide diversity of structural phenomena. The basic structural framework of this region can be discussed in terms of the present structural position of the Precambrian crystalline basement. The basic divisions based on this scheme are: 1—Canadian shield; 2—thinly covered shield; 3—area of locally exposed basement; 4—area of deeply buried basement; and 5—the area where the basement is no longer recognizable.

The Rocky Mountain system as a whole constitutes a belt of deformation which developed in Laramide time. The presence of large crustal folds in which the basement is involved is not typical of the deformation which usually arises from the shelf area that lay adjacent to a trough site of deposition. Factors involved in this development as well as local variations on the general pattern are discussed.