Unique geomorphologic features in ocean basins
Abyssal plains
- Nearly level floors of ocean basins lie beneath 3.5-5 km of water
- Largely featureless, but with some local relief
- Abyssal hills rise < 1km above abyssal plains
- Seamounts rise > 1 km above abyssal plains
- Underlain by young sedimentary rocks that are distinct from those found fringing the continents
- Basement is oceanic rock (basalts or gabbros)