Euan Soutter , Ian Kane, David Hodgson, Stephen S. Flint

The continental shelf-break defines the boundary between shallow- and deep-ocean environments, and is modified by subaerial and submarine processes through geological time. The physiography of the shelf-break therefore records the cumulative influence of these processes, and dictates where, and how efficiently, particulates and pollutants are transported into the deep-ocean. Despite its importance, the continuous along-margin physiography of the shelf-break, and its link to subaerial and submarine processes, remains unquantified on a continental scale. Using a combination of bathymetric data, signal processing and machine learning, we quantify how the physiography of the shelf-break varies continuously along the Americas continental margin. Results show that tectonics exert a first-order control on shelf-break physiography, with the narrowest and deepest canyons associated with small and steep tectonically-active catchments, and steep and narrow shelves. This suggests a dominance of tectonics over climatic and oceanographic factors in shaping submarine geomorphology on a continental scale, supporting the view that particulates and pollutants are most efficiently captured from their source and dispersed to the deep ocean along active margins.