continental shelf

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continental shelf:

see oceanocean,
interconnected mass of saltwater covering 70.78% of the surface of the earth, often called the world ocean. It is subdivided into four (or five) major units that are separated from each other in most cases by the continental masses. See also oceanography.
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Continental Shelf

 

relatively shallow submarine plain adjacent to the shores of the continents and genetically constituting a part of the continent. It was formerly assumed that its outer boundary was located at a depth of 200 m, but research conducted in the 1950’s and 1960’s demonstrated that its outer edge may be located at various depths, in some cases down to 1,500-2,000 m (for example, in the South Kuril trough of the Sea of Okhotsk and on the New Zealand submarine plateau).


Continental Shelf

 

the comparatively level part of the underwater margin of the continent adjacent to the coast and characterized by the same geological structure. The boundaries of the continental shelf are the shores of the sea or ocean and the shelf break (an abrupt increase of the declivity of the sea floor, the transition to the continental slope). The depth at the shelf break is close to 100–200 m, but in some cases reaches 500–1,500 m, for example, at the southern part of the Sea of Okhotsk and the shelf break of the New Zealand Shelf.

The continental shelf as a historical geological category has existed in all geological periods, prograding considerably in some, such as the Jurassic and Cretaceous periods, while retrograding in others, for example, the Permian and Devonian periods. The present geological epoch is characterized by a moderate development of the shelves.

The continental shelf is part of the underwater margin of the continent and has a continental crust. The coast and the shelf have similar geomorphological features. Various relict subaerial forms of relief and deposits are widespread, as are many traces of ancient shorelines, which indicate that the shelf formed primarily as a result of the inundation of the continental margins by the world ocean in postglacial times and as a result of recent tectonic subsidences of the earth’s surface. Also widespread are shelves formed as a result of the retreat of shores through the action of abrasion or as a result of the underwater accumulation of thick deposits of sediments near the continental margins.

The total area of continental shelves is about 32 million sq km. The largest shelf areas are found along the northern margin of Eurasia, where it is 1,500 km wide, in the Bering Sea, Hudson Bay, the South China Sea, and along the northern coast of Australia.

The continental shelf has been used for fishing and hunting sea mammals since ancient times; 92 percent of all the fish caught commercially are caught in shelf waters. Prospecting for minerals, especially petroleum and gas, has developed extensively in the shelf area. In 1975 petroleum extracted from the shelf accounted for 20 percent of all the petroleum extracted in the world; placer deposits of minerals, such as cassiterite, titano-magnetite, diamonds, and gold, are also exploited.

The international legal status of the continental shelf is regulated by a special convention adopted in Geneva in 1958. In the Convention on the Continental Shelf, the term “continental shelf” refers to “(a) the seabed and subsoil of the submarine areas adjacent to the coast but outside the area of the territorial sea, to a depth of 200 m or, beyond that limit, to where the depth of superjacent waters admits of the exploitation of the natural resources of the set area; (b) the seabed and subsoil of similar submarine areas adjacent to the coasts of islands.” The convention acknowledges the sovereign right of coastal states to explore and exploit the natural resources of the shelf, including mineral and other nonliving resources of the seabed and subsoil and living organisms attached to the seafloor or moving along it, such as corals, sponges, mussels, and crabs. Other states do not have the right to do this without the consent of the coastal state.

As a general principle, the boundary of the continental shelf is determined by agreement between interested states in conformity with the rules established by the convention. Such agreements have been concluded by the Soviet Union with Finland (May 20, 1965, and May 6, 1967) and with Poland (Aug. 28, 1969). In addition, the USSR, Poland, and the Democratic Republic of Germany signed a declaration on the continental shelf of the Baltic Sea on Oct. 23, 1968, which established the general principles for delineating the shelf in this region.

A special aspect of the legal status of the continental shelf is that it does not involve the legal status of the superjacent waters of the high seas and the air space above these waters. According to the convention, a coastal state has the right to build, maintain, and operate necessary structures and installations on the shelf and to create a 600-meter safety zone around such structures and installations, as well as to take any necessary steps to protect them. It is stipulated that these structures, installations, and safety zones must not be on important international sea-lanes.

REFERENCES

Leont’ev, O. K. Dno okeana. Moscow, 1968.
Shepard, F. P. Morskaia geologiia, 2nd ed. Leningrad, 1969. (Translated from English.)
Kartirovanie shel’fov: Sb. st. Leningrad, 1974.
Problemy geologii shel’fa: Sb. st. Moscow, 1975.
Ostrovnye shel’fy tropicheskoi zony okeana. Moscow, 1975.
Khrustalev, Iu. P. Mineral’nye bogatstva Mirovogo okeana. Rostov-on-Don, 1975.
Slevich, S. B. Shel’f: Osvoenie i ispol’zovanie. Leningrad, 1977.
Molodtsov, S. V. Mezhdunarodno-pravovoi rezhim otkrytogo moría i kontinental’nogo shel’fa. Moscow, 1960.
Kalinkin, G. F., and Ia. A. Ostrovskii. Morskoe dno: komu ono prinadlezhif? Moscow, 1970.
Zhudro, A. K., and Iu. Kh. Dzhavad. Morskoe pravo. Moscow, 1974.

continental shelf

[¦känt·ən¦ent·əl ′shelf]
(geology)
The zone around a continent, that part of the continental margin extending from the shoreline and the continental slope; composes with the continental slope the continental terrace. Also known as continental platform; shelf.

continental shelf

the sea bed surrounding a continent at depths of up to about 200 metres (100 fathoms), at the edge of which the continental slope drops steeply to the ocean floor.
References in periodicals archive ?
Russia is following the 'rules' regarding the determination of extended continental shelves and it is not surprising that given its size, its sovereign rights over the Arctic seabed will be substantial (equivalent to the size of Mongolia).
Using existing datasets and following the parameters and conditions set out in Article 76, the Geological Survey of Canada (GSC) and Canadian Hydrographic Service (CHS) conducted a desktop study in the mid 1990s to get a preliminary indication of Canada's extended continental shelves (Fig.
The Arctic Ocean coastal states (Canada, Russia, Norway, Denmark and the US) are all in the process of defining their extended continental shelves, although they are at different stages.
and the LORITA working group, 2010, Sedimentary and crustal structure from the Ellesmere Island and Greenland continental shelves onto the Lomonosov Ridge, Arctic Ocean: Geophysical Journal International, v.
Continental shelves are rich in marine life and mineral resources.
convention also defines rights for new continental shelves in waters beyond the 200-nautical-mile mark if the sediment has reached a certain thickness.
The world of the oceans is therefore now made up of continental shelves that are continental shelves and continental shelves that are not.
Although the 1982 Convention has given States without significant continental shelves a uniform broad legal shelf of 200 nautical miles, it could not, by the nature of things, award landlocked States any such right, though landlocked States are given rights to fish in the exclusive economic zones of coastal States under certain conditions
Rampant photosynthesis pulled billions of tons of carbon dioxide out of the air, and this carbon got quickly buried on the continental shelves.
His current research interests include boundary layer dynamics and sediment transport processes through in situ measurements of instrumented seabed landers, offshore geohazards and mobility of large-scale bedforms through multibeam and sidescan surveys and sampling, physical and numerical models of hydrodynamics and sediment transport processes on continental shelves and in coastal environments.
This scenario focuses on the interplay between changing sea levels and the growth of calcium carbonate coral reefs on the continental shelves.
When the ice sheets melted at the end of the glacial period, sea levels rose and coral reefs regrew on the continental shelves.

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