There was a triple junction of three ridges between the Kula Plate to the north, the Pacific Plate to the west and the Farallon Plate to the east. The Kula Plate was subducted under the North American Plate at a relatively steep angle, so that the Canadian Rockies are primarily composed of thrusted sedimentary sheets with relatively little contribution of continental uplift, while the American Rockies are characterized by significant continental uplift in response to the shallow subduction of the Farallon Plate.
... depict the natural history of the island that formed 55 million years ago when volcanic and sedimentary rock from the KulaPacific plate converged into North America (£10; royalbcmuseum.bc.ca).