Abstract: Large U- and V-shaped submarine valleys and intervening ridges on the continental slope southeast of Sable Island Bank are only partially veneered with late Pleistocene to Holocene gray-pale olive green silty clay. Older Pleistocene reddish-brown mud-sand-pebble admixtures locally crop out in the vicinity of dissected topography. The scalloped slope topography, lack of continuation of some major slope valleys onto the lower rise, and exposure of Pleistocene units reflect important mass-gravity in this area during the Quaternary. Broad mounds that form the lower termination of valleys, some of them covering more than 25 km2, are probably toes of enormous subaqueous gravity slides of Pleistocene or older age. Cores penetrating contorted, mixed Pleistocene and Holocene glacio-marine sediments indicate that slumping has continued until recent time.
