AbstractIn the Nahoni Range of the northern Ogilvie Mountains, Yukon Territory, Canada, dissection channels are most markedly developed on valley sides facing the north and north-east. The extent of slope channelling is controlled by intensity of insolation and its influence on persistence of snow and ice. Upon the cooler north- and north-east-facing slopes, snow and ice remain well into midsummer; melt water is released over a long period and its discharge is restricted to narrow rivulets. In contrast, snow and ice on the warmer west- and south-facing slopes melt rapidly during the late spring months. The scree on these valley sides moves down-slope as a more or less uniform mass of water-saturated detritus.