Anlantic Ocean

Atlantic Ocean

From Wikipedia, the free encyclopedia

This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations where appropriate. (November 2010)

"Atlantic", "North Atlantic", and "South Atlantic" redirect here. For Atlantic Basin, see Atlantic (disambiguation), North Atlantic (disambiguation), and South Atlantic (disambiguation).

The Atlantic Ocean, not including Arcticand Antarctic regions.

Earth's oceans (World Ocean)
Arctic Ocean Atlantic Ocean Indian Ocean Pacific Ocean Southern Ocean

The Atlantic Ocean is the second-largest of the world'soceanic divisions. With a total area of about 106,400,000 square kilometres (41,100,000 sq mi), it covers approximately twenty percent of the Earth's surface and about twenty-six percent of its water surface area. The first part of its name refers to Atlas of Greek mythology, making the Atlantic the "Sea of Atlas".

The oldest known mention of "Atlantic" is in The Historiesof Herodotus around 450 BC (Hdt. 1.202.4): Atlantis thalassa (Greek: Ἀτλαντὶς θάλασσα; English: Sea of Atlas); see also: Atlas Mountains. Another name historically used^[who?] was the ancient term Ethiopic Ocean, derived from Ethiopia, whose name was sometimes used as asynonym for all of Africa and thus for the ocean.^{[citation needed]} Before Europeans discovered other oceans, the term "ocean" itself was synonymous with the waters beyond theStrait of Gibraltar that we now know as the Atlantic. The Greeks believed this ocean to be a gigantic river encircling the world.

The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between the Americas to the west, and Eurasia and Africa to the east. As one component of the interconnected global ocean, it is connected in the north to the Arctic Ocean (which is sometimes considered a sea of the Atlantic), to the Pacific Ocean in the southwest, the Indian Ocean in the southeast, and the Southern Ocean in the south. (Other definitions describe the Atlantic as extending southward to Antarctica.) The equator subdivides it into the North Atlantic Ocean and South Atlantic Ocean.

Contents  [hide] 1 Geography 1.1 Extent 2 Cultural significance 3 Ocean bottom 4 Water characteristics 5 Climate 6 History 6.1 Notable crossings 7 Ethiopic Ocean 8 Economy 9 Terrain 9.1 Natural resources 9.2 Natural hazards 10 Current environmental issues 10.1 Marine pollution 11 Major ports and harbours 12 See also 13 References 14 Bibliography 15 External links

[edit]Geography

The Atlantic Ocean as seen from the western coast of Portugal

The Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea,Norwegian Sea and Barents Sea. To the east, the boundaries of the ocean proper are Europe; the Strait of Gibraltar (where it connects with the Mediterranean Sea – one of its marginal seas – and, in turn, theBlack Sea) and Africa.

In the southeast, the Atlantic merges into the Indian Ocean. The 20° East meridian, running south fromCape Agulhas to Antarctica defines its border. Some authorities show it extending south to Antarctica, while others show it bounded at the 60° parallel by the Southern Ocean.^[1]

In the southwest, the Drake Passage connects it to the Pacific Ocean. The man-made Panama Canallinks the Atlantic and Pacific. Besides those mentioned, other large bodies of water adjacent to the Atlantic are the Caribbean Sea; the Gulf of Mexico; Hudson Bay; the Arctic Ocean; the Mediterranean Sea; the North Sea; the Baltic Sea and the Celtic Sea.

Covering approximately 22% of Earth's surface, the Atlantic is second in size to the Pacific. With its adjacent seas, it occupies an area of about 106,400,000 square kilometres (41,100,000 sq mi); without them, it has an area of 82,400,000 square kilometres (31,800,000 sq mi). The land that drains into the Atlantic covers four times that of either the Pacific or Indian oceans. The volume of the Atlantic with its adjacent seas is 354,700,000 cubic kilometers (85,100,000 cu mi) and without them 323,600,000 cubic kilometres (77,640,000 cu mi).

The average depth of the Atlantic, with its adjacent seas, is 3,339 metres (10,955 ft); without them it is 3,926 metres (12,881 ft). The greatest depth, 8,605 metres (28,232 ft), is in the Puerto Rico Trench. The Atlantic's width varies from 2,848 kilometres (1,770 mi) between Brazil and Sierra Leone to over 6,400 km (4,000 mi) in the south.

[edit]Extent

Main article: Borders of the oceans#Atlantic Ocean

[edit]Cultural significance

This section requires expansion.

Transatlantic travel played a major role in the expansion of Western civilization into the Americas. It is the Atlantic that separates "Old world" from "New world". In modern times, some idioms refer to the ocean in a humorously diminutive way as the Pond, describing both the geographical and cultural divide between North America and Europe, in particular between the English-speaking nations of both continents. Many British people refer to the USA and Canada as "across the pond", and vice versa.^[2]

[edit]Ocean bottom

Map that uses color to show ocean depth

The principal feature of the bathymetry (bottom topography) is a submarine mountain range called the Mid-Atlantic Ridge.^[3] It extends from Iceland in the north to approximately 58° South latitude, reaching a maximum width of about 1,600 kilometres (990 mi). A great rift valleyalso extends along the ridge over most of its length. The depth of water at the apex of the ridge is less than 2,700 metres (8,900 ft) in most places, the bottom of the ridge is three times as deep and of course several peaks rise above the water and form islands.^[4] The South Atlantic Ocean has an additional submarine ridge, the Walvis Ridge.^[5]

The Mid-Atlantic Ridge separates the Atlantic Ocean into two large troughs with depths from 3,700–5,500 metres (12,100–18,000 ft). Transverse ridges running between the continents and the Mid-Atlantic Ridge divide the ocean floor into numerous basins. Some of the larger basins are the Blake, Guiana, North American, Cape Verde, and Canaries basins in the North Atlantic. The largest South Atlantic basins are the Angola, Cape, Argentina, and Brazil basins.

The deep ocean floor is thought to be fairly flat with occasional deeps, abyssal plains, trenches,seamounts, basins, plateaus, canyons, and some guyots. Various shelves along the margins of the continents constitute about 11% of the bottom topography with few deep channels cut across the continental rise. The Northern Sea and Nova Scotia included the Atlantic Hook in its prehistoric past, which has since detached because of continental drift.

Ocean floor trenches and seamounts:

• Puerto Rico Trench, in the North Atlantic, is the deepest trench at 8,605 metres (28,232 ft)^[6]
• Laurentian Abyss is found off the eastern coast of Canada
• South Sandwich Trench reaches a depth of 8,428 metres (27,651 ft)
• Romanche Trench is located near the equator and reaches a depth of about 7,454 metres (24,455 ft).

Ocean sediments are composed of:

• Terrigenous deposits with land origins, consisting of sand, mud, and rock particles formed by erosion, weathering, and volcanic activity on land washed to sea. These materials are found mostly on the continental shelves and are thickest near large river mouths or off desert coasts.
• Pelagic deposits, which contain the remains of organisms that sink to the ocean floor, include red clays and Globigerina, pteropod, and siliceous oozes. Covering most of the ocean floor and ranging in thickness from 60–3,300 metres (200–10,800 ft) they are thickest in the convergence belts, notably at the Hamilton Ridge and in upwelling zones.
• Authigenic deposits consist of such materials as manganese nodules. They occur where sedimentation proceeds slowly or where currents sort the deposits, such as in the Hewett Curve.

[edit