The current Rocky Mountains were raised in the Laramide orogeny from between 80 and 55 Ma. For the Canadian Rockies, the mountain building is analogous to a rug being pushed on a hardwood floor: the rug bunches up and forms wrinkles (mountains). In Canada, the subduction of the Kula plate and the terranes smashing into the continent are the feet pushing the rug, the ancestral rocks are the rug, and the Canadian Shield in the middle of the continent is the hardwood floor.