ABSTRACT
Sediment movement in, and some hydrological characteristics of, bedrock gullies on steep mountain slopes are described. Data are presented from a measurement and monitoring study at four sites in the Mt. Rae area of the Canadian Rocky Mountains between 1979 and 1984. Sediment movement was monitored using painted and numbered clasts arranged in transects. Observations and measurements of snowmelt- and rainstorm-generated discharge indicate intermittent surface and subnival flows capable of transporting sediment. Mean annual movement distances of marked clasts by transect ranged from less than 1 m to greater than 50 m. Mean values in these gullies exceed by an order of magnitude movements in such processes as debris shift on open slopes, but variability is generally the same as previously published variability measures. Large spatial and temporal variability in movement are suggestive of intermittent and spatially confined transport agents such as ephemeral streamflow. Mixing of channel bed sediments, imbrication in reworked channel bed deposits, and incision in debris pockets within the bedrock channels are also indicative of fluvial activity. Evidence presented in this chapter indicates that intermittent fluvial activity is an effective erosional agent in the high mountain, periglacial environment.
