Twenty kilogrammes of crusts and slabs of indurated carbonate sediment, usually referred to
as hardgrounds, were dredged along the eastern steep wall of the Bannock Basin during the
1984 cruise of RV Bannock. The crusts range in thickness from one to a few centimetres and
the fragments of these crusts are irregular in shape. Their surface is always uneven and their
colour ranges from white to brownish dark grey. Some slabs are impregnated along one
side by ferromanganese sesquioxides, and borings occur in several samples. Serpulid …