A large, glacially modified, shelf-edge canyon, Scotian Shelf, Atlantic Canada

Abstract

Located on the Scotian Shelf, The Gully is the largest submarine canyon on the outer southeastern Canadian continental margin (Fig. 1a, b). It indents the continental shelf much deeper than other canyons on the Scotian margin, connecting the middle shelf to the continental slope. It is generally recognized that The Gully formed by fluvial, glacial and meltwater erosion that cut deeply into Cenozoic mudstone and sandstone units (Fader et al. 1998). It was excavated over the past million years as successive continental glaciations lowered sea level, exposing the shelf and allowing rivers to erode and deposit sediments near the top of the continental slope. The Gully was also partially eroded by turbidity currents that flowed down the canyon at times of glacial maxima. Fig. 1. Multibeam swath bathymetry and bathymetric profiles of The Gully, Scotian Shelf, Atlantic Canada. ( a ) Sun-illuminated multibeam-bathymetric image of The Gully and the adjacent Scotian shelf and slope showing feeder canyons, bathymetric profile locations and bathymetric isobaths that define the limits of The Gully. Acquisition system Kongsberg EM1000. Frequency 95 kHz. Grid-cell size 10–20 m. Isobaths are in metres. ( b ) Location of study area (red box; map from GEBCO_08). ( c ) Change in slope image featuring curvilinear moraines on the eastern flank of The Gully. ( d ) Bathymetric profile of …