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96-644: Source waters for the Benguela include cold upwelled waters from the depths of the Atlantic Ocean close inshore, joined further off-shore by nutrient poor water that has crossed the Southern Atlantic from South America as part of South Atlantic Gyre . Eddies from the warm South Indian Ocean Agulhas current along South Africa's east coast come round the Cape of Good Hope from time to time to join

192-492: A World Heritage Site for their geological value, four of them are considered of "Outstanding Universal Value" based on their cultural and natural criteria: Þingvellir , Iceland; Landscape of the Pico Island Vineyard Culture , Portugal; Gough and Inaccessible Islands , United Kingdom; and Brazilian Atlantic Islands: Fernando de Noronha and Atol das Rocas Reserves, Brazil. Continental shelves in

288-506: A Navy Sonic Depth Finder to draw a continuous map across the bed of the Atlantic. This involved little guesswork because the idea of sonar is straightforward with pulses being sent from the vessel, which bounce off the ocean floor, then return to the vessel. 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

384-721: A branch of the Gulf Stream which flows northward from the Grand Banks ; and the Subpolar Front , an extension of the North Atlantic Current, a wide, vaguely defined region separating the subtropical gyre from the subpolar gyre. This system of currents transports warm water into the North Atlantic, without which temperatures in the North Atlantic and Europe would plunge dramatically. North of

480-422: A continuous body of water with relatively free interchange among its parts is of fundamental importance to oceanography . The major oceanic divisions are defined in part by the continents , various archipelagos , and other criteria. The principal divisions (in descending order of area) are the: Pacific Ocean , Atlantic Ocean , Indian Ocean , Southern (Antarctic) Ocean , and Arctic Ocean . Smaller regions of

576-416: A weak Intertropical Convergence Zone , South Atlantic tropical cyclones are rare. The Atlantic Ocean is underlain mostly by dense mafic oceanic crust made up of basalt and gabbro and overlain by fine clay, silt and siliceous ooze on the abyssal plain. The continental margins and continental shelf mark lower density, but greater thickness felsic continental rock that is often much older than that of

672-621: Is a complex of four water masses, two that form by deep convection in the open ocean – classical and upper Labrador sea water – and two that form from the inflow of dense water across the Greenland-Iceland-Scotland sill – Denmark Strait and Iceland-Scotland overflow water. Along its path across Earth the composition of the NADW is affected by other water masses, especially Antarctic bottom water and Mediterranean overflow water. The NADW

768-542: Is available at the European Marine Gazetteer website. See also the list of seas article for the seas included in each ocean area. Also note there are many varying definitions of the world's seas and no single authority. The world ocean is divided into a number of principal oceanic areas that are delimited by the continents and various oceanographic features: these divisions are the Atlantic Ocean , Arctic Ocean (sometimes considered an estuary of

864-467: Is fed by a flow of warm shallow water into the northern North Atlantic which is responsible for the anomalous warm climate in Europe. Changes in the formation of NADW have been linked to global climate changes in the past. Since human-made substances were introduced into the environment, the path of the NADW can be traced throughout its course by measuring tritium and radiocarbon from nuclear weapon tests in

960-498: Is found off the eastern coast of Canada. Surface water temperatures, which vary with latitude, current systems, and season and reflect the latitudinal distribution of solar energy, range from below −2 °C (28 °F) to over 30 °C (86 °F). Maximum temperatures occur north of the equator, and minimum values are found in the polar regions. In the middle latitudes, the area of maximum temperature variations, values may vary by 7–8 °C (13–14 °F). From October to June

1056-575: Is interrupted by larger transform faults at two places: the Romanche Trench near the Equator and the Gibbs fracture zone at 53°N . The MAR is a barrier for bottom water, but at these two transform faults deep water currents can pass from one side to the other. The MAR rises 2–3 km (1.2–1.9 mi) above the surrounding ocean floor and its rift valley is the divergent boundary between

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1152-854: Is intersected by two perpendicular ridges: the Azores–Gibraltar Transform Fault , the boundary between the Nubian and Eurasian plates , intersects the MAR at the Azores triple junction , on either side of the Azores microplate, near the 40°N . A much vaguer, nameless boundary, between the North American and South American plates, intersects the MAR near or just north of the Fifteen-Twenty fracture zone , approximately at 16°N . In

1248-729: Is now northern and central Brazil. The formation of the Central American Isthmus closed the Central American Seaway at the end of the Pliocene 2.8 Ma ago. The formation of the isthmus resulted in the migration and extinction of many land-living animals, known as the Great American Interchange , but the closure of the seaway resulted in a "Great American Schism" as it affected ocean currents, salinity, and temperatures in both

1344-794: Is now the Carpathian region, that were similar to the Sargasso Sea. It is possible that the population in the Sargasso Sea migrated to the Atlantic as the Tethys closed at the end of the Miocene around 17 Ma. The origin of the Sargasso fauna and flora remained enigmatic for centuries. The fossils found in the Carpathians in the mid-20th century often called the "quasi-Sargasso assemblage", finally showed that this assemblage originated in

1440-686: Is the ocean that separates Asia and Australia from the Americas . It may be further subdivided by the Equator into northern and southern portions. The 3rd edition, currently in force, of the International Hydrographic Organization 's (IHO) Limits of Oceans and Seas defines the limits of the North Pacific Ocean (excluding the seas it contains) as follows: The 3rd edition, currently in force, of

1536-635: Is the second-largest of the world's five oceanic divisions , with an area of about 85,133,000 km (32,870,000 sq mi). It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery , it was known for separating the New World of the Americas ( North America and South America ) from the Old World of Afro-Eurasia ( Africa , Asia , and Europe ). Through its separation of Afro-Eurasia from

1632-472: The Age of Discovery , the Atlantic was also known to English cartographers as the Great Western Ocean . The pond is a term often used by British and American speakers in reference to the northern Atlantic Ocean, as a form of meiosis , or ironic understatement. It is used mostly when referring to events or circumstances "on this side of the pond" or "on the other side of the pond" or "across

1728-573: The Arctic Ocean differently, as depicted in the map comparing its definition to the IHO's definition. The Atlantic Ocean separates the Americas from Europe and Africa . It may be further subdivided by the Equator into northern and southern portions. The 3rd edition, currently in force, of the International Hydrographic Organization 's (IHO) Limits of Oceans and Seas defines the limits of

1824-564: The Carpathian Basin from where it migrated over Sicily to the central Atlantic where it evolved into modern species of the Sargasso Sea. The location of the spawning ground for European eels remained unknown for decades . In the early 19th century it was discovered that the southern Sargasso Sea is the spawning ground for both the European and American eel and that the former migrate more than 5,000 km (3,100 mi) and

1920-474: The Icelandic Low produces frequent storms. Icebergs are common from early February to the end of July across the shipping lanes near the Grand Banks of Newfoundland . The ice season is longer in the polar regions, but there is little shipping in those areas. Hurricanes are a hazard in the western parts of the North Atlantic during the summer and autumn. Due to a consistently strong wind shear and

2016-597: The International Hydrographic Organization 's (IHO) Limits of Oceans and Seas defines the limits of the South Pacific Ocean (excluding the seas it contains) as follows: Note that these definitions exclude any marginal waterbodies that are separately defined by the IHO (such as the Gulf of Alaska and Coral Sea ), though these are usually considered to be part of the Pacific Ocean. In its 2002 draft,

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2112-793: The Mediterranean Sea . On the South. The equator , from the coast of Brazil to the Southwestern limit of the Gulf of Guinea . Note that this definition excludes any marginal waterbodies that are separately defined by the IHO (such as the Caribbean Sea and North Sea ), though these are usually considered to be part of the Atlantic Ocean. The 3rd edition (currently in force) of the International Hydrographic Organization 's (IHO) Limits of Oceans and Seas defines

2208-684: The North American and Eurasian plates in the North Atlantic and the South American and African plates in the South Atlantic. The MAR produces basaltic volcanoes in Eyjafjallajökull , Iceland, and pillow lava on the ocean floor. The depth of water at the apex of the ridge is less than 2,700 m (1,500 fathoms ; 8,900  ft ) in most places, while the bottom of the ridge is three times as deep. The MAR

2304-616: The North Atlantic Drift is thought to have at least some influence on climate. For example, the Gulf Stream helps moderate winter temperatures along the coastline of southeastern North America, keeping it warmer in winter along the coast than inland areas. The Gulf Stream also keeps extreme temperatures from occurring on the Florida Peninsula. In the higher latitudes, the North Atlantic Drift, warms

2400-514: The North Atlantic oscillation , occurs. On average, the Atlantic is the saltiest major ocean; surface water salinity in the open ocean ranges from 33 to 37 parts per thousand (3.3–3.7%) by mass and varies with latitude and season. Evaporation, precipitation, river inflow and sea ice melting influence surface salinity values. Although the lowest salinity values are just north of the equator (because of heavy tropical rainfall), in general,

2496-555: The Scotia Sea , and other tributary water bodies. Including these marginal seas the coast line of the Atlantic measures 111,866 km (69,510 mi) compared to 135,663 km (84,297 mi) for the Pacific. Including its marginal seas, the Atlantic covers an area of 106,460,000 km (41,100,000 sq mi) or 23.5% of the global ocean and has a volume of 310,410,900 km (74,471,500 cu mi) or 23.3% of

2592-619: The Titan in Greek mythology , who supported the heavens and who later appeared as a frontispiece in medieval maps and also lent his name to modern atlases . On the other hand, to early Greek sailors and in ancient Greek mythological literature such as the Iliad and the Odyssey , this all-encompassing ocean was instead known as Oceanus , the gigantic river that encircled the world; in contrast to

2688-602: The United Kingdom . From the 16th to 19th centuries, the Atlantic Ocean was the center of both an eponymous slave trade and the Columbian exchange while occasionally hosting naval battles. Such naval battles, as well as growing trade from regional American powers like the United States and Brazil , both increased in degree during the early 20th century, and while no major military conflicts have taken place in

2784-638: The meridional overturning circulation (MOC), the northward heat transport of which is threatened by anthropogenic climate change. Large variations in the subpolar gyre on a decade-century scale, associated with the North Atlantic oscillation , are especially pronounced in Labrador Sea Water , the upper layers of the MOC. The South Atlantic is dominated by the anti-cyclonic southern subtropical gyre. The South Atlantic Central Water originates in this gyre, while Antarctic Intermediate Water originates in

2880-458: The thermocline of the subtropical gyre. The Sargasso Sea in the western North Atlantic can be defined as the area where two species of Sargassum ( S. fluitans and natans ) float, an area 4,000 km (2,500 mi) wide and encircled by the Gulf Stream , North Atlantic Drift , and North Equatorial Current . This population of seaweed probably originated from Tertiary ancestors on

2976-578: The 1870s, the Challenger expedition discovered parts of what is now known as the Mid-Atlantic Ridge, or: An elevated ridge rising to an average height of about 1,900 fathoms [3,500 m; 11,400 ft] below the surface traverses the basins of the North and South Atlantic in a meridianal direction from Cape Farewell, probably its far south at least as Gough Island, following roughly

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3072-618: The 1953 definition it extends south to Antarctica, while in later maps it is bounded at the 60° parallel by the Southern Ocean. The Atlantic has irregular coasts indented by numerous bays, gulfs and seas. These include the Baltic Sea , Black Sea , Caribbean Sea , Davis Strait , Denmark Strait , part of the Drake Passage , Gulf of Mexico , Labrador Sea , Mediterranean Sea , North Sea , Norwegian Sea , almost all of

3168-485: The 1960s and CFCs . The clockwise warm-water North Atlantic Gyre occupies the northern Atlantic, and the counter-clockwise warm-water South Atlantic Gyre appears in the southern Atlantic. In the North Atlantic, surface circulation is dominated by three inter-connected currents: the Gulf Stream which flows north-east from the North American coast at Cape Hatteras ; the North Atlantic Current ,

3264-466: The 3rd edition. The Indian Ocean washes upon southern Asia and separates Africa and Australia . The 3rd edition, currently in force, of the International Hydrographic Organization 's (IHO) Limits of Oceans and Seas defines the limits of the Indian Ocean (excluding the seas it contains) as follows: Note that this definition excludes any marginal waterbodies that are separately defined by

3360-520: The 3rd edition. The boundary of the Indian Ocean is a constitutional issue for Australia. The Imperial South Australia Colonisation Act, 1834 , which established and defined the Colony of South Australia defined South Australia's southern limit as being the "Southern Ocean". This definition was carried through to Australian constitutional law upon the Federation of Australia in 1901. The Pacific

3456-587: The African continent. The icy Benguela and the warm, south-flowing Agulhas current do not meet off the Cape of Good Hope (see diagram on the right, above), but there is a body of water off the South African south coast, east and particularly west of Cape Agulhas that consists of eddies from both currents, so that offshore water temperatures along the south coast of Africa vary chaotically. Northward winds along

3552-522: The Americas, the Atlantic Ocean has played a central role in the development of human society, globalization, and the histories of many nations. While the Norse were the first known humans to cross the Atlantic, it was the expedition of Christopher Columbus in 1492 that proved to be the most consequential. Columbus' expedition ushered in an age of exploration and colonization of the Americas by European powers , most notably Portugal , Spain , France , and

3648-581: The Atlantic and Pacific. Marine organisms on both sides of the isthmus became isolated and either diverged or went extinct. Borders of the oceans The borders of the oceans are the limits of Earth 's oceanic waters . The definition and number of oceans can vary depending on the adopted criteria. The principal divisions (in descending order of area) of the five oceans are the Pacific Ocean , Atlantic Ocean , Indian Ocean , Southern (Antarctic) Ocean , and Arctic Ocean . Smaller regions of

3744-537: The Atlantic are wide off Newfoundland, southernmost South America, and northeastern Europe. In the western Atlantic carbonate platforms dominate large areas, for example, the Blake Plateau and Bermuda Rise . The Atlantic is surrounded by passive margins except at a few locations where active margins form deep trenches : the Puerto Rico Trench (8,376 m or 27,480 ft maximum depth) in

3840-625: The Atlantic include the Challenger expedition and the German Meteor expedition ; as of 2001 , Columbia University 's Lamont–Doherty Earth Observatory and the United States Navy Hydrographic Office conduct research on the ocean. The MAR divides the Atlantic longitudinally into two halves, in each of which a series of basins are delimited by secondary, transverse ridges. The MAR reaches above 2,000 m (6,600 ft) along most of its length, but

3936-403: The Atlantic north of the equator. The coldest zones are in high latitudes, with the coldest regions corresponding to the areas covered by sea ice. Ocean currents influence the climate by transporting warm and cold waters to other regions. The winds that are cooled or warmed when blowing over these currents influence adjacent land areas. The Gulf Stream and its northern extension towards Europe,

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4032-467: The Atlantic recently, the ocean remains a core component of trade around the world. The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Europe and Africa to the east, and the Americas to the west. As one component of the interconnected World Ocean , it is connected in the north to the Arctic Ocean , to the Pacific Ocean in the southwest, the Indian Ocean in

4128-469: The Atlantic sea ' , etym . ' Sea of Atlas ' ) and in The Histories of Herodotus around 450 BC (Hdt. 1.202.4): Atlantis thalassa (Ancient Greek: Ἀτλαντὶς θάλασσα , ' Sea of Atlas ' or ' the Atlantic sea ' ) where the name refers to "the sea beyond the pillars of Heracles " which is said to be part of the sea that surrounds all land. In these uses, the name refers to Atlas ,

4224-596: The Atlantic), Indian Ocean , Pacific Ocean , and the Southern Ocean , defined by the International Hydrographic Organization (IHO) in 2000, the latter being a relatively new addition identified with a distinct ecosystem and a unique impact on global climate. In turn, oceanic waters are interspersed by many smaller seas, gulfs, and bays. If viewed from the southern pole of Earth, the Atlantic, Indian, and Pacific Oceans can be seen as lobes extending northward from

4320-409: The Bahamas, while coarse river outwash sands and silt are common in shallow shelf areas like the Georges Bank . Coarse sand, boulders, and rocks were transported into some areas, such as off the coast of Nova Scotia or the Gulf of Maine during the Pleistocene ice ages. The break-up of Pangaea began in the central Atlantic, between North America and Northwest Africa, where rift basins opened during

4416-525: The Benguela Niño is caused by winds in the west-central equatorial Atlantic Ocean that propagate as subsurface sea temperature anomalies to the African coast. A recent study has demonstrated the importance of local winds in the development of the Benguela Niño off the coast of Namibia and Angola. This local process together with the remote signal from the equatorial regions form the basis of the formation mechanism in which both processes sometimes reinforce each other. Atlantic Ocean The Atlantic Ocean

4512-436: The Benguela Niño, warm, salty waters from the Angola Current move southward, between 15°S and 25°S . This slab of warm salty water extends to 150 km (93 mi) offshore and to 50 m (164 ft) depth. Heavy rains, changes in fish abundance, and temporal proximity to the Pacific El Niño have been observed; however, the causes and effects of the Benguela Niño are not well understood. One research team has shown that

4608-418: The Benguela current. The Benguela current is 200 to 300 km wide and widens further as it flows north and northwest. Its western, seaward edge is well-defined, with many temporary and seasonal eddies and meanders. There is however a well-defined thermal front between the waters associated with the Benguela Upwelling System and those of the eastward flowing Atlantic currents which are not deflected northward by

4704-420: The Benguela system regularly have a duration of 10 days, an optimal period for biological production. It is estimated that the annual biomass production in the Benguela system is 4.7×10 gC/y , making the Benguela system 30 to 65 times more productive per unit area than the global ocean average. While upwelling promotes abundant primary and secondary production in the upper parts of the water column and near

4800-476: The Cape depending on wind systems. Pulses of upwelling induce biological production. In the Benguela system, phytoplankton growth requires a period of upwelling followed by a period of stratification and relatively calm waters. The phytoplankton bloom usually lags the upwelling event by 1 to 4 days and blooms for 4 to 10 days. In order for zooplankton to have a continuous food supply, the phytoplankton blooms must not occur too far apart. Pulses of upwelling in

4896-404: The European shores of the former Tethys Ocean and has, if so, maintained itself by vegetative growth , floating in the ocean for millions of years. Other species endemic to the Sargasso Sea include the sargassum fish , a predator with algae-like appendages which hovers motionless among the Sargassum . Fossils of similar fishes have been found in fossil bays of the former Tethys Ocean, in what

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4992-407: The IHO (such as the Bay of Bengal and Arabian Sea ), though these are usually considered to be part of the Indian Ocean. In its 2002 draft, the IHO redefined the Indian Ocean, moving its southern limit to 60°S, with the waters south of that line identified as the Southern Ocean . This new definition has not yet been ratified (and, in addition, a reservation was lodged in 2003 by Australia.) While

5088-414: The IHO (such as the Bay of Biscay and Gulf of Guinea ), though these are usually considered to be part of the Atlantic Ocean. In its 2002 draft, the IHO redefined the Atlantic Ocean, moving its southern limit to 60°S, with the waters south of that line identified as the Southern Ocean . This new definition has not yet been ratified (and, in addition, a reservation was lodged in 2003 by Australia.) While

5184-439: The IHO redefined the Pacific Ocean, moving its southern limit to 60°S, with the waters south of that line identified as the Southern Ocean . This new definition has not yet been ratified (and, in addition, a reservation was lodged in 2003 by Australia.) While the name "Southern Ocean" is frequently used, some geographic authorities such as the 10th edition of the World Atlas from the U.S. National Geographic Society generally show

5280-405: The Late Triassic and Early Jurassic. This period also saw the first stages of the uplift of the Atlas Mountains. The exact timing is controversial with estimates ranging from 200 to 170 Ma. The opening of the Atlantic Ocean coincided with the initial break-up of the supercontinent Pangaea , both of which were initiated by the eruption of the Central Atlantic Magmatic Province (CAMP), one of

5376-468: The North Atlantic Gyre, the cyclonic North Atlantic Subpolar Gyre plays a key role in climate variability. It is governed by ocean currents from marginal seas and regional topography, rather than being steered by wind, both in the deep ocean and at sea level. The subpolar gyre forms an important part of the global thermohaline circulation . Its eastern portion includes eddying branches of the North Atlantic Current which transport warm, saline waters from

5472-410: The North Atlantic Ocean (excluding the seas it contains) as follows: On the West. The Eastern limits of the Caribbean Sea , the Southeastern limits of the Gulf of Mexico from the North coast of Cuba to Key West , the Southwestern limit of the Bay of Fundy and the Southeastern and Northeastern limits of the Gulf of St. Lawrence . On the North. The Southern limit of Davis Strait from

5568-476: The Northern limit of Beaufort Sea , through the Northwest coast of Prince Patrick Island to Cape Leopold M'Clintock, thence to Cape Murray ( Brook Island [ sic ]) and along the Northwest coast to the extreme Northerly point; to Cape Mackay ( Borden Island ); through the Northwesterly coast of Borden Island to Cape Malloch, to Cape Isachsen ( Ellef Ringnes Island ); to the Northwest point of Meighen Island to Cape Stallworthy ( Axel Heiberg Island ) to Cape Colgate

5664-469: The Northern limit of Kara Sea . From Cape Molotov to the Northern extremity of Kotelni Island – the Northern limit of Laptev Sea . From the Northern extremity of Kotelni Island to the Northern point of Wrangel Island – the Northern limit of East Siberian Sea . From the Northern point of Wrangel Island to Point Barrow – the Northern limit of Chuckchi Sea [ sic ]. From Point Barrow to Cape Land's End on Prince Patrick Island –

5760-437: The South Atlantic, and the "Atmospheric Bridge", which evaporates subtropical Atlantic waters and exports it to the Pacific. The Atlantic Ocean consists of four major, upper water masses with distinct temperature and salinity. The Atlantic subarctic upper water in the northernmost North Atlantic is the source for subarctic intermediate water and North Atlantic intermediate water. North Atlantic central water can be divided into

5856-429: The Southern Ocean. Farther north, the Atlantic opens into the Arctic Ocean, which is connected to the Pacific by the Bering Strait , forming a continuous expanse of water. The five oceans are: The Arctic Ocean covers much of the Arctic and washes upon Northern America and Eurasia . It is sometimes considered a sea or estuary of the Atlantic Ocean. The International Hydrographic Organization (IHO) defines

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5952-405: The Strait of Gibraltar. Despite their names, some smaller landlocked "seas" are not connected with the World Ocean, such as the Caspian Sea (which is nevertheless, geologically, itself a full-fledged ocean—see above) and numerous salt lakes such as the Aral Sea . A complete hierarchy showing which seas belong to which oceans, according to the International Hydrographic Organization (IHO),

6048-412: The West. The limit of the Rio de La Plata . On the North. The Southern limit of the North Atlantic Ocean. On the Northeast. The limit of the Gulf of Guinea . On the Southeast. From Cape Agulhas along the meridian of 20° East to the Antarctic continent . On the South. The Antarctic Continent. Note that these definitions exclude any marginal waterbodies that are separately defined by

6144-412: The atmosphere over the oceans, keeping the British Isles and northwestern Europe mild and cloudy, and not severely cold in winter, like other locations at the same high latitude. The cold water currents contribute to heavy fog off the coast of eastern Canada (the Grand Banks of Newfoundland area) and Africa's northwestern coast. In general, winds transport moisture and air over land areas. Every winter,

6240-403: The coast of Labrador to Greenland and the Southwestern limit of the Greenland Sea and Norwegian Sea from Greenland to the Shetland Islands . On the East. The Northwestern limit of the North Sea , the Northern and Western limits of the Scottish Seas , the Southern limit of the Irish Sea , the Western limits of the Bristol and English Channels , of the Bay of Biscay and of

6336-450: The coast result in Ekman transport offshore and upwelling of nutrient-rich deep water to the euphotic zone . The intensity of the upwelling event is determined by wind strength. Variations in wind strength result in pulses of upwelling, which propagate to the south along the coast with speeds of 5 to 8 m/s. The pulses are similar to a Kelvin wave , except on a scale of 30 to 60 km instead of 1000 km, and can propagate around

6432-506: The coast, deeper waters with limited oxygen exchange create hypoxic areas called oxygen minimum zones at the coastal shelf and upper coastal slope. The Benguela oxygen minimum zone starts around a depth of 100 m and is a few hundred meters thick. Bacteria that use sulphur rather than oxygen, called sulphur-reducing bacteria , reside in the oxygen minimum zone. The most abundant fishes in the Benguela system are Sardinops and Engraulis . The Southern African pilchard ( S. s. ocellatus ),

6528-429: The collision of Cimmeria with Laurasia . The Mediterranean Sea is at times a discrete ocean because tectonic plate movement has repeatedly broken its connection to the World Ocean through the Strait of Gibraltar . The Black Sea is connected to the Mediterranean through the Bosporus , but the Bosporus is a natural canal cut through continental rock some 7,000 years ago, rather than a piece of oceanic sea floor like

6624-431: 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, the Black Sea , both of which also touch upon Asia) and Africa. In the southeast, the Atlantic merges into the Indian Ocean. The 20° East meridian , running south from Cape Agulhas to Antarctica defines its border. In

6720-544: The eastern and western North Atlantic central water since the western part is strongly affected by the Gulf Stream and therefore the upper layer is closer to underlying fresher subpolar intermediate water. The eastern water is saltier because of its proximity to Mediterranean water. North Atlantic central water flows into South Atlantic central water at 15°N . There are five intermediate waters: four low-salinity waters formed at subpolar latitudes and one high-salinity formed through evaporation. Arctic intermediate water flows from

6816-400: The enclosed seas well known to the Greeks: the Mediterranean and the Black Sea. In contrast, the term "Atlantic" originally referred specifically to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the West African coast. The term " Aethiopian Ocean ", derived from Ancient Ethiopia , was applied to the southern Atlantic as late as the mid-19th century. During

6912-527: The extreme West point of Ellesmere Island ; through the North shore of Ellesmere Island to Cape Columbia thence a line to Cape Morris Jesup ( Greenland ). Note that these definitions exclude any marginal waterbodies that are separately defined by the IHO (such as the Kara Sea and East Siberian Sea ), though these are usually considered to be part of the Arctic Ocean. The CIA defines the limits of

7008-517: The latter 2,000 km (1,200 mi). Ocean currents such as the Gulf Stream transport eel larvae from the Sargasso Sea to foraging areas in North America, Europe, and northern Africa. Recent but disputed research suggests that eels possibly use Earth's magnetic field to navigate through the ocean both as larvae and as adults. The climate is influenced by the temperatures of the surface waters and water currents as well as winds. Because of

7104-471: The limits of the Arctic Ocean (excluding the seas it contains) as follows: Between Greenland and West Spitzbergen [ sic ] – The Northern limit of Greenland Sea . Between West Spitzbergen and North East Land – the parallel of lat. 80° N . From Cape Leigh Smith to Cape Kohlsaat – the Northern limit of Barentsz Sea [ sic ]. From Cape Kohlsaat to Cape Molotov –

7200-681: The limits of the South Atlantic Ocean (excluding the seas it contains) as follows: On the Southwest. The meridian of Cape Horn , Chile (67°16'W) from Tierra del Fuego to the Antarctic Continent ; a line from Cape Virgins ( 52°21′S 68°21′W  /  52.350°S 68.350°W  / -52.350; -68.350 ) to Cape Espiritu Santo , Tierra del Fuego, the Eastern entrance to Magellan Strait . On

7296-605: The limits of the oceans and seas in 1953, but some of these definitions have been revised since then and some are not recognized by various authorities, institutions, and countries, for example the CIA World Factbook . Correspondingly, the extent and number of oceans and seas vary. 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

7392-501: The lowest values are in the high latitudes and along coasts where large rivers enter. Maximum salinity values occur at about 25° north and south , in subtropical regions with low rainfall and high evaporation. The high surface salinity in the Atlantic, on which the Atlantic thermohaline circulation is dependent, is maintained by two processes: the Agulhas Leakage/Rings , which brings salty Indian Ocean waters into

7488-514: The margins of the continents constitute about 11% of the bottom topography with few deep channels cut across the continental rise. The mean depth between 60°N and 60°S is 3,730 m (12,240 ft), or close to the average for the global ocean, with a modal depth between 4,000 and 5,000 m (13,000 and 16,000 ft). In the South Atlantic the Walvis Ridge and Rio Grande Rise form barriers to ocean currents. The Laurentian Abyss

7584-596: The maximum depth, the Milwaukee Deep in the Puerto Rico Trench , is 8,376 m (27,480 ft). Top large seas: The bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge (MAR). It runs from 87°N or 300 km (190 mi) south of the North Pole to the subantarctic Bouvet Island at 54°S . Expeditions to explore the bathymertry of

7680-732: The most extensive and voluminous large igneous provinces in Earth's history associated with the Triassic–Jurassic extinction event , one of Earth's major extinction events . Theoliitic dikes , sills , and lava flows from the CAMP eruption at 200 Ma have been found in West Africa, eastern North America, and northern South America. The extent of the volcanism has been estimated to 4.5 × 10  km (1.7 × 10  sq mi) of which 2.5 × 10  km (9.7 × 10  sq mi) covered what

7776-479: The name "Southern Ocean" is frequently used, some geographic authorities such as the 10th edition of the World Atlas from the U.S. National Geographic Society generally show the Atlantic, Indian, and Pacific Oceans continuing to Antarctica. If and when adopted, the 2002 definition would be published in the 4th edition of Limits of Oceans and Seas , re-instituting the 2nd edition's "Southern Ocean", omitted from

7872-419: The name "Southern Ocean" is frequently used, some geographic authorities such as the 10th edition of the World Atlas from the U.S. National Geographic Society generally show the Atlantic, Indian, and Pacific Oceans continuing to Antarctica. If and when adopted, the 2002 definition would be published in the 4th edition of Limits of Oceans and Seas , re-instituting the 2nd edition's "Southern Ocean", omitted from

7968-571: The north to become the source for North Atlantic deep water, south of the Greenland-Scotland sill. These two intermediate waters have different salinity in the western and eastern basins. The wide range of salinities in the North Atlantic is caused by the asymmetry of the northern subtropical gyre and a large number of contributions from a wide range of sources: Labrador Sea, Norwegian-Greenland Sea, Mediterranean, and South Atlantic Intermediate Water. The North Atlantic deep water (NADW)

8064-425: The ocean's great capacity to store and release heat, maritime climates are more moderate and have less extreme seasonal variations than inland climates. Precipitation can be approximated from coastal weather data and air temperature from water temperatures. The oceans are the major source of atmospheric moisture that is obtained through evaporation. Climatic zones vary with latitude; the warmest zones stretch across

8160-606: The oceans are called seas , gulfs , bays , straits , and other terms. Geologically, an ocean is an area of oceanic crust covered by water. Oceanic crust is the thin layer of solidified volcanic basalt that covers the Earth's mantle . Continental crust is thicker but less dense. From this perspective, the Earth has three oceans: the World Ocean, the Caspian Sea , and the Black Sea . The latter two were formed by

8256-508: The oceans are called seas , gulfs , bays , straits , and other terms. Geologically, an ocean is an area of oceanic crust covered by water. See also: List of seas on Earth for the seas included in each oceanic area. Though generally described as several separate oceans, the world's oceanic waters constitute one global, interconnected body of salt water sometimes referred to as the World Ocean or Global Ocean. This concept of

8352-565: The outlines of the coasts of the Old and the New Worlds. The remainder of the ridge was discovered in the 1920s by the German Meteor expedition using echo-sounding equipment. The exploration of the MAR in the 1950s led to the general acceptance of seafloor spreading and plate tectonics . Most of the MAR runs under water but where it reaches the surfaces it has produced volcanic islands. While nine of these have collectively been nominated

8448-595: The pond", rather than to discuss the ocean itself. The term dates to 1640, first appearing in print in a pamphlet released during the reign of Charles I , and reproduced in 1869 in Nehemiah Wallington 's Historical Notices of Events Occurring Chiefly in The Reign of Charles I , where "great Pond" is used in reference to the Atlantic Ocean by Francis Windebank , Charles I's Secretary of State . The International Hydrographic Organization (IHO) defined

8544-438: The seafloor. The oldest oceanic crust in the Atlantic is up to 145 million years and is situated off the west coast of Africa and the east coast of North America, or on either side of the South Atlantic. In many places, the continental shelf and continental slope are covered in thick sedimentary layers. For instance, on the North American side of the ocean, large carbonate deposits formed in warm shallow waters such as Florida and

8640-419: The southeast, and the Southern Ocean in the south. Other definitions describe the Atlantic as extending southward to Antarctica . The Atlantic Ocean is divided in two parts, the northern and southern Atlantic, by the Equator . The oldest known mentions of an "Atlantic" sea come from Stesichorus around mid-sixth century BC (Sch. A. R. 1. 211): Atlantikôi pelágei (Ancient Greek: Ἀτλαντικῷ πελάγει , '

8736-551: The subtropics to the northeastern Atlantic. There this water is cooled during winter and forms return currents that merge along the eastern continental slope of Greenland where they form an intense (40–50  Sv ) current which flows around the continental margins of the Labrador Sea . A third of this water becomes part of the deep portion of the North Atlantic Deep Water (NADW). The NADW, in turn, feeds

8832-421: The surface is usually covered with sea ice in the Labrador Sea , Denmark Strait , and Baltic Sea. The Coriolis effect circulates North Atlantic water in a clockwise direction, whereas South Atlantic water circulates counter-clockwise. The south tides in the Atlantic Ocean are semi-diurnal; that is, two high tides occur every 24 lunar hours. In latitudes above 40° North some east–west oscillation, known as

8928-428: The total volume of the Earth's oceans. Excluding its marginal seas, the Atlantic covers 81,760,000 km (31,570,000 sq mi) and has a volume of 305,811,900 km (73,368,200 cu mi). The North Atlantic covers 41,490,000 km (16,020,000 sq mi) (11.5%) and the South Atlantic 40,270,000 km (15,550,000 sq mi) (11.1%). The average depth is 3,646 m (11,962 ft) and

9024-520: The upper layers of the circumpolar region, near the Drake Passage and the Falkland Islands. Both these currents receive some contribution from the Indian Ocean. On the African east coast, the small cyclonic Angola Gyre lies embedded in the large subtropical gyre. The southern subtropical gyre is partly masked by a wind-induced Ekman layer . The residence time of the gyre is 4.4–8.5 years. North Atlantic Deep Water flows southward below

9120-424: The western Atlantic and South Sandwich Trench (8,264 m or 27,113 ft) in the South Atlantic. There are numerous submarine canyons off northeastern North America, western Europe, and northwestern Africa. Some of these canyons extend along the continental rises and farther into the abyssal plains as deep-sea channels. In 1922, a historic moment in cartography and oceanography occurred. The USS Stewart used

9216-658: Was intensely fished in the 1950s and peaking in 1968 with landings over 1.3 million tons. Since then, fishery of the Sardinops has declined and fishery of the Southern African anchovy ( Engraulis capensis ) has taken over. Similar to the Pacific El Niño , a thick slab of warm, nutrient-poor water enters the northern part of the Benguela upwelling system off the Namibia coast about once per decade. During

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