STREAM-VALLEY ASYMMETRY IN AN ARCTIC-SUBARCTIC ENVIRONMENT: CONDITIONS GOVERNING THE GEOMORPHIC PROCESSES.

Abstract : A sample of 210 slope profiles from (1) plateau-top, (2) upper and (3) lower valley locations in the Caribou Hills, N.W.T., was analyzed according to a statistical experiment designed to elucidate the phenomenon and controls of valley asymmetry. The chief factors examined were topographic position (which involves changing elevation, climate, vegetation and immediate relief) and the combination of slope aspect and stream position. Supplementary data on soil moisture, vegetation cover, and evaporation were incorporated. Despite the complex geomorphic situation in the area, the experiment established that asymmetry exists, and reverses from category (3) (above) to categories (2) and (1). North-facing slopes are generally steeper in the higher elevations where snow-banks and nivation are important, and particularly are found lower on the slope profile. South-facing slopes are steeper in the lower valleys where vegetation is sparse because of a summer water deficiency, and channel erosion by tributaries is more intense. Here, the slopes are kept at about the maximum angle that the parent material, weakly consolidated sands and claystones will stand. (Author)