Relief of the ocean floor
Also called: Ocean floor divisions · Topic: Oceans: Hydrological Cycle, Relief of the Ocean Floor, Temperature and Salinity · NCERT: Class 11, Ch 12 "Water (Oceans)"
Meaning
Relief of the ocean floor means the shape of the land under the sea. Most of the ocean floor lies 3–6 km deep. It is as uneven as the land, with the biggest mountain ranges, the deepest trenches and the largest plains on Earth. Plate movements, volcanoes and the build-up of sediment shape it. It has four major divisions:
- Continental shelf: usually less than 200 m deep
- Continental slope: about 200–3,000 m deep
- Deep-sea (abyssal) plain: about 3,000–6,000 m deep
- Oceanic deeps (trenches): the deepest parts
Example
Off western India, the Arabian Sea floor starts with a wide shelf that holds the Bombay High oilfield. Further out, it drops down the slope to deep plains.
Don't confuse with
- Minor relief features: ridges, seamounts, guyots and canyons are minor features. Oceanic deeps are one of the four major divisions, not a minor feature.
Related concepts
- Continental margin
- Continental shelf
- Continental slope
- Abyssal plain
- Oceanic trench
- Mariana Trench
- Puerto Rico Trench
- Sunda Trench