Geology of the Rocky Mountains
The Canadian Rockies are quite different in appearance and geology from the American Rockies to the south of them. The Canadian Rockies are composed of layered sedimentary rock such as limestone and shale, where as the American Rockies are made mostly of metamorphic and igneous rock such as gneiss and granite. The American Rockies are, on average, higher in elevation than the Canadian Rockies, but have less vertical relief, which is to say they are shorter from base to summit because the mountain valleys are higher. The Canadian Rockies are more jagged than the American Rockies, because the Canadian Rockies have been very heavily glaciated, resulting in sharply pointed mountains separated by wide, U-shaped valleys gauged by glaciers, where as the American Rockies are more rounded, with river-carved V-shaped valleys between them. The Canadian Rockies are cooler and wetter, giving them moister soil, bigger rivers, and more glaciers. The tree line is much lower in the Canadian Rockies than in the American Rockies. The geology of the Rocky Mountains is that of a discontinuous series of mountain ranges with distinct geological origins. Collectively these make up the Rocky Mountains, a mountain system that stretches from Canada through central New Mexico and which is part of the great mountain system known as the North American Cordillera. The rocks making up the mountains were formed before the mountains were raised. The cores of the mountain ranges are in most places formed of pieces of continental crust that are over one billion years old. In the south, an older mountain r
nge was formed 300 million years ago, then eroded away. The rocks of that older range were reformed into the Rocky Mountains. The Rocky Mountains took shape during an intense period of plate tectonic activity that resulted in much of the rugged landscape of the western North America. The Laramide orogeny, about 80-55 million years ago, was the last of the three episodes and was responsible for raising the Rocky Mountains. Subsequent erosion by glaciers has created the final form of the mountains. The rocks in the Rocky Mountains were formed before the mountains were raised by tectonic forces. The oldest rock is Precambrian metamorphic rock that forms the core of the North American continent. There is also Precambrian sedimentary argillite, dating back to 1.7 billion years ago. During the Paleozoic, western North America lay underneath a shallow sea, which deposited many kilometers of limestone and dolomite. In the southern Rocky Mountains, near present-day Colorado, these ancestral rocks were disturbed by mountain building approximately 300Ma, during the Pennsylvanian. This mountain building produced the Ancestral Rocky Mountains. The uplift created two large mountainous islands, known to geologists as Frontrangia and Uncompahgria, located roughly in the current locations of the Front Range and the San Juan Mountains. They consisted largely of Precambrian metamorphic rock forced upward through layers of the limestone laid down in the shallow sea. The mountains eroded throughout the late Paleozoic and early Mesozoic, leaving extensive deposits of sedimentary rock.
More information about Fernie Alpine Chalet: