In this area, mobile sand bedforms move over a predominantly gravel substrate. Ripples and other bedforms on the lower slope indicate both NE and SW directed currents, although some current indicators, such as comet marks around large boulders, may be relict. In the Faeroe-Shetland Channel, widespread gravel at the seabed on the lower continental slope and on the basin floor is largely a relict from the late glacial. Gravel has remained unburied primarily due to very low sedimentation rates during the Holocene, rather than to erosion by bottom currents, although the latter may have contributed to the overall low sedimentation rate by preventing deposition of fine grained sediment. In the northern Rockall Trough, bottom currents are the main agent of sediment transport at all depths on the continental slope down to at least 1,500 m.
Currents are towards the northeast on the eastern margin of the trough.
However, below the crest of the Wyville-Thomson Ridge, at about 500 m water depth, these currents are deflected to the west and then southwest by the ridge topography. No mounds have been discovered north of the Wyville-Thomson Ridge. The factors controlling the location of the carbonate mound fields are not understood at the present time. Numerous colonies of the deep-water coral Lophelia pertusa were found on the carbonate mounds. Elsewhere in the areas surveyed during 1996 and 1998, Lophelia has only been encountered sporadically as small isolated colonies.