This report is a contribution to the Strategic Environmental Assessment (SEA7) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). Investigations of the hydrocarbon prospectivity and earthquake activity include the whole of SEA7 but in this report investigations of the sea-bed sediments are restricted to the Hebrides Shelf, Rockall Trough and east Rockall Bank.
On the Hebrides Shelf, Hebrides Slope, east Rockall Bank and in the deep-water Rockall Trough the modern sea-bed sediments are mainly composed of mixtures of former glacial deposits and grains of modern interglacial biogenic carbonate shell. Former glacial deposits and modern biogenic carbonate are now mainly mixed and transported by wave-orbital currents and residual currents on Rockall Bank and by combinations of wave-orbital currents, tidal currents and residual currents on the Hebrides Shelf and upper Hebrides Slope. Below approximately 300 metres water depth in the Rockall Trough the sea-bed sediments are mainly transported by circulating deep-water residual currents.