Description: The sill geomorphic feature layer represents the spatial extent of the sills of the worlds oceans based on interpretation of the SRTM30 plus v7 global bathymetry model. The layer is one of the 25 layers that make up the global seafloor geomorphic features map (Harris et.al. 2014). Sills are “a sea floor barrier of relatively shallow depth restricting water movement between basins” (IHO, 2008). Thus every basin has a sill, over which fluid would escape if the basin were filled to overflowing. The identification of sills in this study is based on selecting contours at a specified interval of 10 m (shelf except for Antarctica), 50 m (Antarctic shelf) or 100 m (all other areas) depending upon the location. Selecting the most shoal, closed contour defines the basin; one contour interval above this typically identifies a discrete location where contours “escape” from the basin and join into the regional bathymetry. This location is mapped as the sill. Sills were mapped for all of the major ocean basins and seas and for the larger basins perched on the continental shelf; sills were not mapped for the smaller basins perched on the slope or shelf or for the smaller abyssal basins.
Copyright Text: The global seafloor geomorphic features map has been produced through a collaboration between Geoscience Australia, GRID-Arendal and Conservation International.
Reference: Harris et. al. (2014) Geomorphology of the oceans.Marine Geology (in Press)