Ocean Floor:
Also referred to as the seabed, the structure of the ocean floor is shaped by plate tectonics. The majority of the ocean floor consists of deep areas called abyssal plains.
Major divisions of the oceanic relief
The ocean floors can be divided into four major divisions:
(i) The Continental Shelf
This is the extended margin of each continent that is submerged under relatively shallow seas and gulfs.
It is the shallowest part of the ocean, with a gradient of about 1° or less.
Continental shelves typically have an average width of around 80 kilometers, though some, like the coasts of Chile and Sumatra’s west coast, may be very narrow or virtually absent. Conversely, the Siberian shelf in the Arctic Ocean is the widest, extending up to 1,500 kilometers.
These shelves are covered with varying layers of sediment transported from land by rivers, glaciers, wind, and distributed by waves and currents.
(ii) The Continental Slope
The continental slope is the area that connects the continental shelf to the ocean basins. It begins at the edge of the continental shelf and descends steeply.
The slope's gradient ranges from 2 to 5 degrees.
Depths in this region vary between 200 and 3,000 meters. This area marks the end of the continental crust and features canyons and pits.
(iii) The Deep Sea Plain
These are gently sloping areas within ocean basins, characterized by being the flattest and smoothest regions on Earth.
The deep sea plains are covered with fine-grained sediments, including clay and silt.
(iv) The Oceanic Deeps
These are the deepest sections of the ocean, known as trenches, which are narrow, steep-sided basins that are approximately 3 to 5 kilometers deeper than the surrounding ocean floor.
Oceanic deeps are usually found at the base of continental slopes and along island arcs, and are associated with active volcanic activity and significant earthquake zones.
The ocean floor holds vast quantities of metals and rare earths. Many countries and corporations are interested in the commercial potential of deep-sea mining. The UN’s sea convention stipulates that any activities in the high seas must be equitably shared among states, and that would include profits from deep-sea mining.
