Bathymetry: Features and Hypsography

The study of the distribution of elevations on the Earth or hypsography shows how more than half of the world ocean is dominated by deep basins (4–6.5 km) covered with abyssal plains and hills. Seafl oor from 2 to 4 km depth is primarily comprised of oceanic ridge systems that spread over ~30% of the seafl oor. The shallow seas and continental margins from sea level to 2 km depth cover the least amount of area and represent only ~15% of the seafl oor. Superimposed on the primary features of the seafl oor landscape are secondary features such as the median valley, seamounts, and submarine canyons. Finescale geomorphology of the underwater landscape and discontinuities in bathymetry are increasingly being used to assess distributions of marine organisms. New terminology and computational methods identify seafl oor features that enhance marine biodiversity and allow for better management of vulnerable marine ecosystems.