Linear to curvilinear depressions on high-latitude continental shelves have long been regarded as the signature of the ploughing action of iceberg keels impinging on the sedimentary sea-floor (e.g. Woodworth-Lynas et al. 1991). These depressions vary in dimensions and pattern with the size of calved icebergs and their drift tracks through the polar seas. Two different sizes of iceberg appear to have affected the continental shelf north of Svalbard, producing distinctive sets of ploughmarks (Dowdeswell et al. 2010).