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Ocean Relief – Meaning – Types – Roles

by Sekar Puspa

creatures, environment, reliefOcean relief is the outcome of the great depressions of the earth’s outer layer mostly on the bottom surface. The bottom surface of the ocean or known as ‘land’ under the waters of the ocean floor creating the complex and varied features.

As a result, there are deepest trenches and the largest plains on the ocean floor as well. They are formed due to the presence of many factors including the factors of tectonic, volcanic, and depositional processes.

Indeed, this case means that ocean bottom and ocean floor are not plain, yet, has various relief. In addition, ocean floor has the portion of 3-6 km below the sea level.

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Consequently, as ocean floors provide the various form of ocean relief, then the ocean floors can be divided into four divisions as written below.

Major Ocean Relief

It is known that ocean relief has the major structure relief which is laid on the ocean floor. The major structure formed by the natural processes such as tectonic. Hence, here is the list of major ocean relief below.

  • Continental Shelf

What is continental shelf? Well, it is known that this shelf typically ends at a very steep slope so that it is called as the shelf break. The continental shelves are almost absent or very narrow along some of the margins. The average width of continental shelves is around 80 km while they have the various depth as well. Moreover, the continental shelf is the extended margin of each continent occupied by shallow seas and gulfs. It also becomes the shallowest part of the ocean with an average gradient of 1° or even less. What makes this ocean floor is by the coverage of variable thicknesses of sediments by rivers, glaciers, and wind. (see also: Marine Protected Areas)

In addition, the continental shelf s formed due to the submergence of a part of a continent, the relative rise in sea level, and the sedimentary deposits brought down by the rivers. As the consequence, the example of the continental shelf is the Great Banks and Newfoundland. (see also: Effects of Ocean Currents)

Further, continental shelf provides marine food and it contains richest fishing grounds. For this reason, it becomes the good source of minerals like petroleum and gas as well as other kinds of mineral like gold, manganese, iron, and copper. At this point, what makes this ocean relief has rich creatures is the way many ocean plants and many types of algae live in the sunny waters. Sunlight penetrates the shallow waters and many kinds of ocean organisms live in there. Therefore, it brings nutrients to organisms for sure. (see also: Ocean Layers)

  • Continental Slope

The next one is the presence of continental slope which connects the continental shelf and the ocean basins. It presents where the bottom of continental shelf sharply drops off into a steep slope and has the various gradient between 2-5°. Not only the various gradient, but the depth of this type also varies between 200 and 3,000 m. Further, the continental slope takes 8.5% of the total ocean area. (see also: Facts of Dead Sea)

  • Deep Sea Plain

Talking about deep sea plain results in the presence of gently sloping areas of the ocean basins. As a result, these become the flattest and smoothest regions of the worlds. They also have the various depth between 3,000 and 6,000 m. Then, what makes this a relief is by the coverage of fine-grained sediments like clay and silt.

As the consequence, these abyssal plains occur at depths of over 1,980 m below the sea level which are underlain by the oceanic crust. Also, these deep sea plains are commonly found in all major ocean basins including in the Atlantic and Indian ocean basins. (see also: Volcano under the Ocean)

  • Oceanic Deeps or Trenches

As a matter of fact, oceanic deeps or also called as the trenches are the deepest parts of the oceans. It is known that the trenches have the steep side and the narrow basins. They also have 3-5 km deeper than the surrounding ocean floor. They belong to the bases of continental slopes and along island arcs. Moreover, what makes the occurrence of trenches is the presence of active volcanoes and strong earthquakes include the endogenetic forces which have produced the mountains. Furthermore, the ocean deeps have the depth range of 7,000 to 9,000 meters. Also, ocean deeps can be found in the Caribbean Sea and the Pacific Ocean. Still, the greatest known ocean deep is the challenge point of Mariana Trench near Guam Island while there are other ones like Mindanao Deep, Tonga Trench, and Japanese Trench in the Pacific Ocean.

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After talking about the major part of ocean relief, then there are also the minor of ocean relief which written below.

Minor Ocean Relief

Apart from the presence of major ocean relief, there is also minor ocean relief. Minor ocean relief is divided into some parts including the mid-oceanic ridges, guyots, seamounts, and others. Thus, if you want to know the detail information of minor ocean relief, then kindly check the following statements below.

  • Mid-Oceanic Ridges

The first minor ocean relief is the one named Mid-Oceanic Ridges which is formed of two chains of mountains separated by a large depression. Mid-Oceanic Ridges become the largest mountain systems on earth as it has the total length of 75,000 km. As the consequence, mid-ocean ridges formed by the tectonics process and caused by seafloor spreading like magma rising through the crust and emerging as lava. Indeed, they are formed of the tectonic process which Iceland as the example of this mid-Atlantic Ridge. (read also: Sea Salt Facts)

  • Submarine Canyons

Submarine canyons are existed by cutting across the continental shelves and slopes which are extending from the mouths of large rivers. The example of this ocean relief is the Hudson Canyon as the best-known submarine canyon in the world. Moreover, the large canyons in the world in the Bering Sea of Alaska.

Submarine canyons also refer to the steep-sided valley cut into the seabed of the continental slope and have the canyon wall with the height of up to 5 km from the canyon floor to canyon rim. As the consequence, submarine canyons formed by the occurrence of two main processes. They are the erosion and the mass casting of the continental slope. At this point, there are an estimated 9,477 submarine canyons on earth with Amazon Canyon, Congo Canyon, Hudson Canyon as the examples. (read also: Effects of Greenhouse)

  • Seamount

As a matter of fact, there are many mountains on ocean floors. Consequently, seamount is also being categorized as the ocean relief as it has pointed summits which are rising from the seafloor. It also does not reach the surface of the ocean. It also has the 3,000 – 4,500 m tall. Then, it turns out that many seamounts are in the Gulf of Alaska.

It also turns amounts are the common marine ecosystems which bring interaction between seamounts and underwater currents. Seamounts provide habitat for numerous fish and other marine animals such as sharks, tuna, and cephalopods With the presence of seamount, it helps the living of corals, plankton, fish, and other marine mammals. Besides, not only providing great habitats for marine mammals, but seamounts are heavily populated with the presence of corals. (See also: Salinity of Ocean Water)

As a result, many seamounts support commercial fishing industries as well. Indeed, it brings the negative impact of fishing on seamount ecosystem. Since the over fisheries bring bad impacts to the fish populations in seamounts, then it will need the good management practices of fisheries. Then, with the good management, there will no depleting stock number of fish for sure. (see also: Endangered Sea Turtles List)

  • Guyots

The next minor ocean relief is the presence of guyots. This one is linked with the seamount as guyots are also known as the flat-topped seamount. They occur as the evidence of gradual subsidence through stages then becoming the flat-topped submerged mountains. As the consequence, Guyot has the flat top over 200m below the surface pf the sea and has the diameters that can exceed 10 km. Furthermore, guyots are also linked with the specific lifeforms as well. (see also: Surface of Tension Liquids)

  • Atoll

Atoll refers to the low islands found in the tropical oceans and consists the coral reefs surroundings the central depression. Next, Atoll can be a part of the sea or the form of enclosing a body of fresh or highly saline water as well. This also refers to the coral reef which has the ring shape that encircles a lagoon partially or completely. Moreover, the atoll coral often sits atop the rim of an extinct seamount or eroded volcano which partially beneath the water. It is also known that Atolls are the product of the tropical marine organisms growth. As a result, corals of the atoll will only thrive in warm tropical and subtropical waters of the ocean. Then, atolls are commonly found in the Pacifica Ocean, Marshall Islands, and the Indian Ocean. (See also: Marine Disasters)

  • Fracture Zones

The next one is fracture zone which is the linear oceanic feature resulting from by the action of offset mid-ocean ridge axis segments. It is also formed by the presence of plate tectonics. What causes fractures in the ocean floor is by the mid-ocean ridges activities. As mid-ocean ridges push apart two plates and let the either side of it be moved and transformed faults due to the variances in plate motion, then the movement makes the offset which causes the fractures. Furthermore, there are the lists of the fracture zone in the ocean such as the Blanco fracture zone, Charlie-Gibbs Fracture Zone, Mendocino fracture zone, Romanche fracture zone, and Solano fracture zone. Further, fracture zones have the zone of 125 km long and 15 km wide. (see also: Sea Erosion)

  • Island Arcs

Island arcs are often composed of a chain of volcanoes wth arc-shaped alignment and close to the boundary between two converging tectonic plates. Indeed, arcs are the formation of one oceanic tectonic plate which produces magma at the depth below the over-riding plate. (See also: How to Prevent El Nino)

There is a term which states the difference between island arcs and volcanic island arcs. As a result, volcanic arcs are the shape mountain belt which commonly causes by volcanoes composed while island arcs are not volcanic. At this point, the arc shape formed by the geometry of the spherical plate along a line on a spherical surface.

  • Escarpment

Talking about escarpment refers to a topic which explains the long cliff formed by faulting or erosion and separates two level areas of differing elevations. It also means that escarpment refers to the margin between two landforms or steep slope.

Moreover, the escarpment has generally involved the processes of differential erosion of sedimentary rocks or the vertical movement of the Earth’s crust. Indeed, it is the formation of the transition from one series of sedimentary rocks to another series of a different age and composition. Not only for that, escarpment are often caused by the faults which place the ground surface so that one side becomes higher than the other one. Further, sea scraps belong to the zone between coastal lowlands and continental plateaus. (see also: Ocean Coral Reef)

  • Bank

One of ocean relief features is the one called as a Bank. It is a flat-topped elevation located in the continental margins and becomes the sites of the most productive fisheries in the world. This one occurs due to the process of the erosional and depositional activity. As the consequence, ocean banks are often formed by the volcanic nature or can be the submerged atolls. Moreover, banks can be carbonate which are the rising platforms from the ocean depths or terrigenous which is due to the elevation of sedimentary deposits. Moreover, the example of Bank is the Grand Bank in the north-western Atlantic, Newfoundland. (See also: Marine Energy)

  • Shoal

It is known that a shoal is a detached elevation with shallow depths and is dangerous for navigation. Moreover, a shoal refers to the natural submerged ridge, bank, or bar which consists of sand or other material and rises from the bed of body water. It is also often called as the sandbars or gravel bars as well. Shoals are the long and narrow ridges which resulting in the shallowing of the water and appear as the coastal landform in the sea. The composition of the shoal is the sand and the grain size of the material is linked to the size or strength of the waves which moves the material.

There are two types of shoals which include sandbars that are available where the waves are breaking and occur in the seaward of a trough and the river bar that is a sedimentary deposit. This is due to the freshwater sediment deposit or the waves action as well. (See also: Acidification of the Ocean)

  • Reef

A reef or coral reef is the organic deposit formed by living or dead marine organisms. Also, reef creates a mound or rocky elevation like a ridge. Coral reefs have been the great marine ecosystem in the ocean. It is also linked with seamounts and guyots as well. Consequently, reefs can be up to 261 feet or 0 m below the surface. Moreover, reefs are the formation of the abiotic process, sand deposition, wave erosion, and other natural processes. Then, coral reefs made by biotic processes involved of corals and calcareous algae. Therefore, as corals take the great ecosystem in the ocean, then the become the major contributors of marine living organisms.

As the consequence, coral reefs plays a role in becoming the great barrier from storms in the ocean. It also supports the habitat for the diversity of fish including algae, sponges, and invertebrates. Indeed, coral reefs can protect the marine living for sure. As a result, it takes part in balancing the ocean food chain as well. What is even great is that the reefs can filter the water and enhance the water quality.

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Roles of Ocean Relief

As you have read above, there are types of ocean relief which present on the ocean floor. Then, you may wonder what benefits and roles of them. As the consequence, we have also listed the roles of ocean relief below. Check it out!

  • Ocean relief can control the motion of sea water as it has various depths and widths as well.
  • The movement in ocean currents can cause many variations in both oceans and in the atmosphere.
  • Ocean relief where take places at the bottom of the ocean can influence the navigation and fishing. At this point, the different feature of ocean relief may provide different marine creatures. Then, it will enable the various action of fisheries. (read also: Types of Sea Urchins)

As the conclusion, due to the natural processes occur in the ocean floor, then the processes affect the appearance of the bottom of the ocean. Indeed, this one affects in the building of the different ocean relief. Then, as you have read the information about ocean relief above, now you have known what types and roles of ocean relief as well.

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