In the days of dinosaurs, southern Alberta was a flat coastal marshland. For over 50 million years, dinosaurs fed on lush vegetation, or on other dinosaurs. After the dinosaurs died, their bones were fossilized into the rocks. Dead vegetation rotted and was buried, and over time the great temperatures and pressures created Alberta's oil & gas and its coal. Over millions of years, the rock layers became hardened and compressed into visible layers.
Southern Alberta region became famous because of the 1884 dinosaur bone discoveries of Joseph Tyrell, a geologist with the Canadian Pacific Railway, in the badlands 100 km east of Calgary where the dinosaur bones were exposed by erosion. In the mountains, the dinosaur bones have been exposed through lifting. In the 1950s the continental drift theory of continents was proven as ocean floors were mapped using sonar (underwater radar, invented to find submarines in the Second World War). The mountains were created as tectonic plates of land pushed against each other, some being forced to tremendous elevation. This creates some unusual rock lines in the mountains, with some layers rising from the valley floor to the mountain peaks, and other layers roll up and down like ocean waves.
After the mountains were lifted from sea level, they were subject to erosion by wind and rain, but also by high elevation glacier, and by valley glaciers during the ice ages. Several North American ice ages (the most recent only 10,000 years ago) smoothed the land the east of the mountains to create the fertile western plains that feed the world.
More history of the Canadian Rockies