Submarine fans seaward of mid-latitude glacial ice streams in cross-shelf troughs show a complex evolution. Unlike high-latitude fans where glacigenic debris-flows predominate, meltwater discharge appears to play a larger role in fan evolution, reflected in the growth of high channel-levees and the development of broad, flat-floored submarine valleys. Where canyons are deeply incised, large mass-transport events may be triggered leading to much of the mid-fan area being constructed of mass-transport deposits (MTDs). The Laurentian and Northeast fans are two large submarine fans that lie seawards of major glacial cross-shelf troughs on the continental margin south of Nova Scotia, Canada (Fig. 1a). Both fans span more than 300 km from the shelf break to the Sohm Abyssal Plain. The fans have well-developed channel-levee systems with the western levee of the Laurentian Fan forming a major constructional feature on the margin (Fig. 1c, e). Multibeam and side-scan data coverage of the fans is more complete for the lower fan of Northeast Fan and for the middle and upper fan of Laurentian Fan. Fig. 1. Multibeam bathymetry, backscatter, side-scan and seismic-reflection data over large mid-latitude trough-mouth fans south of …