ABSTRACT The upper continental slope in the Arctic Ocean off Alaska and northwestern Canada is characterized by a series of low mounds and troughs. These features are found only between the edge of the shelf and the 200-fathom isobath on the slope, and on the sides of two shelf valleys. The origin of this microrelief is not clear, but the evidence available suggests that it is best explained as formed by mass movement on low slopes in regions where tides are small and tidal currents are weak.