Shape and Size:

The Arctic Ocean is almost circular in shape and surrounds the North Pole of the earth. Its total area is about 14 million km2, which is only 8.3 percent of the area of the Pacific Ocean. The characteristic feature of this ocean is that it is surrounded on all sides by land masses except at a few places where it is connected with the Atlantic and the Pacific oceans.

At 170°W this ocean is connected with the Pacific Ocean through the Bering Strait. But the waters of this Polar Basin mix with those of the Atlantic Ocean through the open seas between Greenland, Iceland and British Islands. According to the Russian scientists, the Arctic Ocean is of recent origin. The estimated age of this ocean is approximately one lakh years.

Until recently our knowledge about the Arctic Ocean was rather very scanty. But recent explorations by the Soviet Russia practically revolutionized our knowledge of the polar seas. According to Defant, however, this ocean can be regarded as a continuation of the Atlantic Ocean across the Greenland-Iceland-Faroes Ridge, and the American and European Mediterranean Seas.

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This ocean is divided into two basins by a great central ridge extending from the Novo Sibirskie Islands through the North Pole to Greenland and Ellesmere Land. The length of this ridge is 1800 kilometers, and it is also named as Lomonosov Ridge.

The basin near the northern coast of Eurasia is called the Eurasia Basin, and that close to the American coast is named as The Amer- asia Basin. The width of the central ridge varies from 64 km to 200 km in different parts.

The ridge has steep slopes, spurs and saddles in different localities. Recent exploration has succeeded in discovering a few deeps also, which are of varying depths ranging from 3820 m to 5220 m.

Bottom Relief

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Continental Shelf:

The continental shelf to the north of Alaska and Greenland is 96-192 km wide. But along the north coast of Eurasia the shelf becomes much wider, its width ranging from 480 km to 1960 km. There are several submarine valleys on the continental shelf. On the Santa Anna shelf is found the biggest depression which is 480 km long and 176 km wide.

The continental shelf in the eastern and northern part of the ocean basin is relatively wider varying from 160 to 640 km in width. However, in the west of North America and Greenland the width of the shelf has decreased considerably.

It is said that the Arctic Ocean has the singular distinction of having the widest continental shelf. The Canadian Archipelago, Greenland and several island groups of Eurasia rise on the Arctic continental shelves.

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Ridges and Basins:

Since the Arctic Ocean remains frozen throughout the year, the detailed knowledge of its bottom relief could not be obtained. However, as stated earlier, the most important ridge is the central Lomonosov Ridge.

The depth of water over the higher elevations of the ridge ranges from 517-900 fathoms. In fact, the Trans-Arctic extension of the Mid-Atlantic Ridge, which is known as the Nansen Ridge, divides the Eurasian Basin into two parts.

The geographic North Pole has been located in the Fram Basin which is 2345 fathoms deep, and is surrounded by the Nansen and Lomonosov Ridges. The Nansen Basin (2300 fathoms) is situated in the middle of the Nansen Cordillera and the coast of Eurasia. The Alpha Cordillera divides the Amerasia Basin into two sub-basins.

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The Makarob Basin surrounded by Alpha and Lomonosov Ridges is 2200 fathoms deep. The Canada Basin happens to be the biggest one. It is situated between the Beaufort shelf and the Alpha Ridge. The average depth of this basin is 2091 fathoms.

Islands of the Arctic Ocean:

The rim of the Arctic Basin is dotted with a large number of islands. Some of the large and extensive islands like the Canadian Archipelago, the New Siberian Islands, and Novaya Zemlya are in fact parts of the submerged margins of the land-masses with broad continental shelves. There are some other islands like Spitzbergen, Bear Island and Jan Mayen which represent the higher parts of the submarine ridges.

Marginal Seas :

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The Arctic Ocean is characterized by a large number of marginal seas on its coastal regions. However, most of them are situated along the northern coasts of the land masses. Off the coast of Alaska there lies the Beaufort Sea; whereas the East Siberian Sea and Laptev Sea are situated along the Siberian coast.

The Kara Sea lies between the mouth of the river Ob draining into the Arctic Basin and the Island of Novaya Zemlya. Lastly, there is the Barents Sea situated between Spitzbergen and Norway. It should be borne in mind that all the marginal seas of the Arctic Ocean are shallow, and remain frozen almost all the year round.