Continental rises – Criteria for identification of continental rises include the occurrence of a smooth sloping seabed as indicated by evenly-spaced, slope-parallel contours (eg. Curray et al., 2002; Dowdeswell et al., 2008; Covault et al., 2011). In this study, the term “Rise” was restricted to features that abut continental margins and does not include the mid-ocean ridge (or “rise”), which was mapped as a separate feature.  The GEBCO Gazetteer of geographic names of undersea features (IHO-IOC, 2012) was used to ensure all named features were included. There is considerable variability in the mean thickness of sediment characterising rises in the different ocean regions, ranging from around 450 m in the South Pacific to over 3,100 m in the Indian Ocean.

Most continental rises occur adjacent to passive continental margins; the continental rise covers more than 27.1 million km2 adjacent to passive margins and less than 2.3 million km2 adjacent to active margins.  The continental rise completely surrounds Antarctica covering 39.4% of the Southern Ocean (see Table), forming a halo of sediment surrounding the Antarctic continent.

Example of continental rise (in yellow) and submarine fan (red) adjacent to the coast of southeastern Brazil.  Grey shading represents abyssal plain (white) abyssal hills (light grey) and abyssal mountains (dark grey).

Statistics on continental rises (from Harris et al., 2014).  The percentage areas refer to ocean regions and the percentage of the abyssal zone that is continental rise. Sediment thickness data derived from the global sediment thickness map of Divins (2003) and from a map for the Arctic Ocean region published by Jackson and Oakey (1990).

OceanArea km2Rise area%%Area of abyssal zone that is RiseNumber of RisesMean sediment thickness (m)Sediment thickness Std Dev
Arctic Ocean906,8306.9817.061,276677
Indian Ocean6,244,2008.769.94113,1262,611
Mediterranean and Black Sea384,91012.727.47No data
North Atlantic Ocean7,823,57017.523.2142,8142,093
North Pacific Ocean976,9101.191.4252,2641,719
South Atlantic Ocean6,234,08015.417.082,0451,299
South Pacific Ocean556,7100.6390.695452233
Southern Ocean6,704,84033.039.441,729891
All Oceans29,832,0408.249.7355

Covault , J.A., 2011. Submarine Fans and Canyon-Channel Systems: A Review of Processes, Products, and Models. Nature Education Knowledge 3, 893-894.

Curray, J.R., Emmel, F.J., Moore, D.G., 2002. The Bengal Fan: morphology, geometry, stratigraphy, history and processes. Marine and Petroleum Geology 19, 1191–1223.

Divins, D., 2003. Total Sediment Thickness of the World’s Oceans and Marginal Seas. NOAA National Geophysical Data Center.

Dowdeswell, J.A., Cofaigh, C., Noormets, R., Larter, R.D., Hillenbrand, C.D., Benetti, S., Evans, J., Pudsey, C.J., 2008. A major trough-mouth fan on the continental margin of the Bellingshausen Sea, West Antarctica: The Belgica Fan. Marine Geology 252, 129-140.

Harris, P.T., MacMillan-Lawler, M., Rupp, J., Baker, E.K., 2014. Geomorphology of the oceans. Marine Geology 352, 4-24.

IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organisation and Intergovernmental Oceanographic Commission, Monaco, p. 32.

IHO-IOC, 2012. GEBCO Gazetteer of Undersea Feature Names, October 2012 version,

Jackson, H.R., Oakey, G.N., 1990. Sedimentary thickness map of the Arctic Ocean. In: Grantz, A. et al. (Eds.), The Arctic Ocean Region, Vol. L. Geological Society of America, The Geology of North America, Boulder, Plate 5.

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