ABSTRACT

Two regional structural salients of the Rocky Mountains meet in the vicinity of Crowsnest Pass where they are represented by north-trending structures that occur in conjunction with, and are partly superimposed upon, northwest-trending structures Two distinct phases of orogenic deformation can be recognized in this region. The older is represented by relatively shallow west and southwest-dipping thrust faults, some of which are rather tightly folded themselves, and by concordant folds; the younger by west-dipping normal faults along which large blocks have been tilted toward the east. Four principal structural units, all of which are intimately related but differ in tectonic level and style, occur between Coleman, Alberta and the valley of Elk River in British Columbia. These are: the Coleman fault plate, the Lewis thrust sheet, the Alexander fault plate, and the Fernie basin. Interpretations of the structural geometry are illustrated in a group of serial sections.