Heli Ski Mountain Ranges: the formation of the Rockies
The formation of mountains doesn’t happen overnight – it is a slow process that takes millions of years. Until relatively recently in mans history no one could come up with a feasible theory to explain how these great structures could have come to be. The Himalayas, the Rockies, the Andes; all of these massive ranges must have be formed somehow, but it took a while until geologists were in union about just how.
Here, near us in BC, there are three main mountain ranges: the Coastal Mountains, the Skeena Mountains and the Rockies. By far the most expansive, holding the Continental Divide and attracting millions of visitors a year, are the Rocky Mountains, and this is how they were formed.
To understand how mountains arose in the first place we need to understand basic plate tectonics. This is the well-established theory that the earth is made up of a series of plates covering the surface of the earth, each moving relatively and independently of the others. At one time in history, all these plates were joined as one large land mass known as Pangea. Over time this huge continent broke up into smaller plates, and as these plates began to drift they inevitably began colliding into each other – with mountainous consequences.
‘Orogenies’ is the name given to separate periods of mountain building. In this area of Canada two separate ‘orogenies’ are responsible for the formation of the mountains we see today.
Initially, there was a North American Plate moving in a westerly direction, and a Pacific Plate moving northwards. From the movement of the Pacific Plate, two landmasses, known as terranes, were formed, literally by the ‘bulldozing’ of the chain of islands that stood in the way.
When the northern moving Pacific Plate collided with the North American Plate, the crust on which it had been moving was forced into the Earth’s surface. In between the two plates, the first of the two terranes were sandwiched. Being too buoyant enough to be pushed under like the crust, it ended up becoming part of the edge of the continent. This is the first ‘orogeny’ and the resultant forces compressing the already existent landmasses formed the Columbia Mountains (including the Caribous, Selkirks, Purcells and the Monashees).
From these collisions a huge shock wave was born. This in turn disrupted the huge masses of rock in its path, which cracked and slide up over neighboring rocks. This process, known as thrust faulting, was partially to thank for the formation of the Rockies.
A while later (actually around 85 million years ago) the second of the two terranes collided. This set about a whole new set of shock waves that provided the energy needed to form the foothills and front ranges of the Rockies. Dying out as they reached Calgary, the forces left the prairies undisturbed.