The surface of the globe covered by water is greater than that corresponding to emerging land. Until the 20th century, the interior of this enormous liquid mass was a mystery and, even today, we know very little about it.
Under the surface of the sea a landscape of very accentuated relief extends, where new terrestrial crust is constantly formed and that houses many unknowns for science. The ocean floor remains the great unknown.
The average depth of the oceans is about four or five kilometers that, compared to the thousands of km they cover, make us see that they are thin layers of water on the planet's surface. But the depth is very variable depending on the area. We can differentiate five zones:
The Continental platform It is the continuation of the continents under water, with depths ranging from 0 meters on the coast line to about 200 m. It occupies about 10% of the ocean area. It is an area of great exploitation of oil and fishing resources.
He Slope It is the area of steep slope that leads from the limit of the continental shelf to the ocean floor. They appear split, from time to time, by underwater canyons carved by sediments that slide in large currents that fall from the platform to the ocean floor.
He ocean floor It has a depth of between 2,000 and 6,000 meters and occupies about 80% of the ocean area.
The dorsal chains Oceanic are elongated surveys of the ocean floor that run along more than 60,000 km. In them the volcanic and seismic activity abounds because they correspond to the zones of formation of the lithospheric plates in which the ocean floor is expanding.
The Abyssal Pits they are narrow and elongated areas where the ocean floor descends to more than 10,000 m deep, at some points. They are especially frequent at the edges of the Pacific Ocean and have great volcanic and seismic activity because they correspond to the areas where the plates sink into the mantle.
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