The Rocky Mountain region of Alberta covers over half of the province's
western border. Largely due to the width and variety of the mountain terrain the Rocky
Mountain natural region is comprised of a series of topographically
diverse conditions that produce
a unique association of plants and animals, many not found anywhere else
in the province. The major valleys parallel the mountain ranges, and at various points the ranges have been cleft by drainage systems allowing the exit of waters from these valleys. Thus
major river systems leaving the eastern slopes of the Rocky Mountains in Alberta flow in an easterly direction.
The Rocky Mountain Natural Region is part of a major uplift that trends along the western part of Alberta forming the Continental Divide. It is
distinguished from the
Foothills Natural Region primarily by structural geology, age and
lithology. The Rocky Mountain Natural Region is underlain primarily by upthrust and folded carbonate and quartzitic
bedrock whereas the Foothills Natural Region is mostly composed of deformed
sandstone and shale.
Exceptions include areas of the Montane Subregion in the
"geological" Foothills of the Porcupine and
Cypress Hills, and occurrences of the Subalpine and Alpine subregions on folded bedrock of the
"geological" Foothills Belt in the Kakwa area.
This Region is the most rugged topographically in Alberta and ranges in width from only 10 kilometres in the
Waterton Lakes National Park
area to more than 100 kilometres in the central portion. Elevations rise from east to west, from major river valleys at 1000 to 1500 metres to 3700 metres along the Continental Divide.
The two major mountain ranges, the easterly Front Ranges and the westerly Main Ranges, are composed mostly of thrust-faulted sediments. Major valleys trend from southeast -northwest through the mountains and are typically occupied by large rivers. Many of Alberta's largest rivers are found within this region where they drain into the Saskatchewan and Mackenzie River systems. The highest mountains occur in the central part of the Region with the lower mountains in the far north and far south. Within the Rocky Mountain Natural Region there have been three natural subregions identified:
Montane, Subalpine and
Alpine, which mainly reflect changes in environmental conditions due to changes in
altitude and aspect.