Atlantic Ocean

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"Atlantic", "North Atlantic", "South Atlantic", "Atlantic Basin", and "Atlantic coast" redirect here. For other uses, see Atlantic (disambiguation), North Atlantic (disambiguation), South Atlantic (disambiguation), Atlantic Basin (disambiguation), and Atlantic Coast (disambiguation).
Atlantic Ocean
Map of the Atlantic Ocean
Basin countries List of countries, ports
Surface area 82,185,000 km2 (31,732,000 sq mi)
North Atlantic: 41,490,000 km2 (16,020,000 sq mi), South Atlantic 40,270,000 km2 (15,550,000 sq mi)[1]
Average depth 3,646 m (11,962 ft)[1]
Max. depth 8,486 m (27,841 ft)[1]
Water volume 305,811,900 km3 (73,368,200 cu mi)[1]
Shore length1 111,866 km (69,510 mi) including marginal seas[2]
Islands List of islands
Trenches Puerto Rico; South Sandwich; Romanche
1 Shore length is not a well-defined measure.
This video was taken by the crew of Expedition 29 on board the ISS. The pass starts from just northeast of the island of Newfoundland over the North Atlantic Ocean to central Africa, over South Sudan.

The Atlantic Ocean is the second largest of the world's oceans with a total area of about 106,460,000 square kilometres (41,100,000 sq mi), slightly more than half that of the Pacific Ocean.[3] It covers approximately 20 percent of the Earth's surface and about 29 percent of its water surface area. It separates the "Old World" from the "New World".

The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Eurasia and Africa to the east, and the Americas to the west. As one component of the interconnected global ocean, it is connected in the north to the Arctic Ocean, 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 Equatorial Counter Current subdivides it into the North Atlantic Ocean and South Atlantic Ocean at about 8°N.[4]


The oldest known mention of "Atlantic" is in The Histories of Herodotus around 450 BC (Hdt. 1.202.4): Atlantis thalassa (Greek: Ἀτλαντὶς θάλασσα; English: Sea of Atlas) where the name refers to "the sea beyond the pillars of Heracles" which is said to be part of the ocean that surrounds all land.[5] Thus, on one hand, the name refers to Atlas, the Titan of Greek mythology, who supported the heavens and who later appeared as a frontispiece in Medieval maps and has thus also lend his name to modern atlases.[6] 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 the enclosed seas well-known to the Greeks: the Mediterranean and the Black Sea.[7] In contrast, the term "Atlantic" originally referred specifically to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the North African coast.[6] The Greek word thalassa has been reused by scientist for the huge ocean Panthalassa that surrounded the supercontinent Pangaea hundreds of million years ago.

The term "Ethiopic Ocean", derived from Ethiopia, was applied to the southern Atlantic as late as the mid-19th century.[8]


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 Irish or British people refer to the United States and Canada as "across the pond", and vice versa.[9]

The "Black Atlantic" refers to the role of this ocean in shaping black people's history, especially through the Atlantic slave trade. Irish migration to the US is meant when the term "The Green Atlantic" is used. The term "Red Atlantic" has been used in reference to the Marxian concept of an Atlantic working class, as well as to the Atlantic experience of indigenous Americans. [10][11][12]

Extent and data[edit]

For complete lists of marginal seas and borders of the Atlantic, see List of seas § Atlantic Ocean, and Borders of the oceans § Atlantic Ocean.
For the extent of the Southern Ocean, see Southern Ocean § Definitions and use.
Extent of the Atlantic Ocean according to the 2002 IHO definition, excluding Arctic and Antarctic regions

The International Hydrographic Organization (IHO) defined the limits of the oceans and seas in 1953,[13] but some of these definitions have been revised since then and some are not used by various authorities, institutions, and countries, see for example the CIA World Factbook. Correspondingly, the extent and number of oceans and seas varies.

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, 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 the 1953 definition it extends south to Antarctica, while in later maps it is bounded at the 60° parallel by the Southern Ocean.[13]

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 the Scotia Sea, and other tributary water bodies.[2] 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.[2][14]

Including its marginal seas, the Atlantic covers an area of 85,133,000 km2 (32,870,000 sq mi) or 23.5 % of the global ocean and has a volume of 310,410,900 km3 (74,471,500 cu mi) or 23.3 %. Excluding the Mediterranean and Baltic, the Atlantic covers 82,185,000 km2 (31,732,000 sq mi) and has a volume of 305,811,900 km3 (73,368,200 cu mi). The North Atlantic covers 41,490,000 km2 (16,020,000 sq mi) (11.5 %) and the South Atlantic 40,270,000 km2 (15,550,000 sq mi) (11.1 %).[1] The average depth is 3,646 m (11,962 ft) and the maximum depth, the Milwaukee Deep in the Puerto Rico Trench, is 8,486 m (27,841 ft).[1][15]


False colour map of ocean depth in the Atlantic basin

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 42°S.[16]

Mid-Atlantic Ridge[edit]

Main article: Mid-Atlantic Ridge

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 2000 m along most of its length, but 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.[17]

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 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.[18] The depth of water at the apex of the ridge is less than 2,700 metres (1,500 fathoms; 8,900 ft) in most places, while the bottom of the ridge is three times as deep.[19]

The MAR 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.[20] 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.[21]

In 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 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 the outlines of the coasts of the Old and the New Worlds.[22]

The remainder of the ridge was discovered in the 1920s by the German Meteor expedition using echo-sounding equipment.[23] The exploration of the MAR in the 1950s lead to the general acceptance of seafloor spreading and plate tectonics.[16]

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 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.[16]

Ocean floor[edit]

For a list of fracture zones in the Atlantic, see List of fracture zones § Atlantic Ocean.

Continental shelves in the Atlantic are wide off Newfoundland, southern-most South America, and north-eastern 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 (8,414 m (27,605 ft) maximum depth) in the western Pacific and South Sandwich Trench (8,264 m (27,113 ft)) in the South Atlantic. There are numerous submarine canyons off north-eastern North America, western Europe, and north-western Africa. Some of these canyons extend along the continental rises and farther into the abyssal plains as deep-sea channels.[17]

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 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).[17]

In the South Atlantic the Walvis Ridge and Rio Grande Rise form barriers to ocean currents. The Laurentian Abyss is found off the eastern coast of Canada.

Water characteristics[edit]

Map displaying a looping line with arrows indicating that water flows eastward in the far Southern ocean, angling north east of Australia, turning sough after passing Alaska, then crossing the mid-Pacific to flow north of Australia, continuing west below Africa, then turning northwest until reaching eastern Canada, then angling east to southern Europe, then finally turning south just below Greenland and flowing down the Americas' eastern coast, and resuming its flow eastward to complete the circle
Path of the thermohaline circulation. Purple paths represent deep-water currents, while blue paths represent surface currents.

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).[4]

From October to June the surface is usually covered with sea ice in the Labrador Sea, Denmark Strait, and Baltic Sea.[4]

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 during each 24 lunar hours. In latitudes above 40° North some east-west oscillation, known as the North Atlantic Oscillation, occurs.[4]


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 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.[4]

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 the South Atlantic, and the "Atmospheric Bridge", which evaporates subtropical Atlantic waters and exports it to the Pacific.[24]

Water masses[edit]

Temperature-salinity characteristics for Atlantic water masses[25]
Water mass Temperature Salinity
Upper waters (0–500 m)
Atlantic Subarctic
Upper Water (ASUW)
0.0–4.0°C 34.0–35.0
Western North Atlantic
Central Water(WNACW)
7.0–20°C 35.0–36.7
Eastern North Atlantic
Central Water (ENACW)
8.0–18.0°C 35.2–36.7
South Atlantic
Central Water (SACW)
5.0–18.0°C 34.3–35.8
Intermediate waters (500–1500 m)
Western Atlantic Subarctic
Intermediate Water (WASIW)
3.0–9.0°C 34.0–35.1
Eastern Atlantic Subarctic
Intermediate Water (EASIW)
3.0–9.0°C 34.4–35.3
Mediterranean Water (MW) 2.6–11.0°C 35.0–36.2
Arctic Intermediate Water (AIW) -1.5–3.0°C 34.7–34.9
Deep and abyssal waters (1500 m–bottom)
North Atlantic
Deep Water (NADW)
1.5–4.0°C 34.8–35.0
Antarctic Bottom Water (AABW) -0.9–1.7°C 34.64–34.72
Arctic Bottom Water (ABW) -1.8–-0.5°C 34.85–34.94

The Atlantic Ocean consists of four major, upper water masses with distinct temperature and salinity. The Atlantic Subarctic Upper Water in the northern-most North Atlantic is the source for Subarctic Intermediate Water and North Atlantic Intermediate Water. North Atlantic Central Water can be divided into 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.[26]

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 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 the large number of contributions from a wide range of sources: Labrador Sea, Norwegian-Greenland Sea, Mediterranean, and South Atlantic Intermediate Water.[26]

The North Atlantic Deep Water (NADW) 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.[27] The NADW 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 man-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 the 1960s and CFCs.[28]


Map showing 5 circles. The first is between western Australia and eastern Africa. The second is between eastern Australia and western South America. The third is between Japan and western North America. Of the two in the Atlantic, one is in hemisphere.
Map of the five major ocean gyres

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.[4]

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, 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 transport warm water into the North Atlantic, without which temperatures in the North Atlantic and Europe would plunge dramatically.[29]

In the subpolar gyre of the North Atlantic warm subtropical waters are transformed into colder subpolar and polar waters. In the Labrador Sea this water flows back to the subtropical gyre.

North of 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.[30] 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 the subtropics to the north-eastern 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 become parts of the deep portion of the North Atlantic Deep Water (NADW). The NADW, in its turn, feed 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.[31]

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 the upper layers of the circumpolar region, near the Drake Passage and 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.[32] 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 southerward below the thermocline of the subtropical gyre.[33]

Sargasso Sea[edit]

Main article: Sargasso Sea
Aproximate extent of the Sargasso Sea

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 the European shores of the former Tethys Ocean and has, if so, maintained itself by vegetative growth, floating in the ocean, for million of years.[34]

Other species endemic to the Sargasso Sea include the sargassum fish, a predator with algae-like appendages who hovers motionless among the Sargassum. Fossils of similar fishes have been found in fossil bays of the former Tethys Ocean, in what 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.[34] 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 the Carpathian Basin from were it migrated over Sicily to the Central Atlantic where it evolved into modern species of the Sargasso Sea.[35]

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 eel and the American eel and that the former migrate more than 5,000 km (3,100 mi) and 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 Europe, Northern Africa, and North America.[36]


Map of Caribbean showing seven approximately parallel westward-pointing arrows that extend from east of the Virgin Islands to Cuba. The southern arrows bend northward just east of the Dominican Republic before straightening out again.
Waves in the trade winds in the Atlantic Ocean—areas of converging winds that move along the same track as the prevailing wind—create instabilities in the atmosphere that may lead to the formation of hurricanes.

Climate is influenced by the temperatures of the surface waters and water currents as well as winds. Because of 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.[4]

The oceans are the major source of the atmospheric moisture that is obtained through evaporation. Climatic zones vary with latitude; the warmest zones stretch across 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 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.[4]

The Gulf Stream and its northern extension towards Europe, the North Atlantic Drift, for example, warms the atmosphere of the British Isles and north-western Europe and influences weather and climate as far south as the northern Mediterranean. The cold water currents contribute to heavy fog off the coast of eastern Canada (the Grand Banks of Newfoundland area) and Africa's north-western coast.[4]

In general, winds transport moisture and air over land areas. Hurricanes develop in the southern part of the North Atlantic Ocean (Hurricanes are rare in the South Atlantic Ocean).[4] More local particular weather examples could be found in examples such as the Azores High, Benguela Current, and Nor'easter.

Natural hazards[edit]

Overhead photo of iceberg
Iceberg A22A in the South Atlantic Ocean

Icebergs are common from February to August in the Davis Strait, Denmark Strait, and the northwestern Atlantic and have been spotted as far south as Bermuda and Madeira. Ships are subject to superstructure icing in the extreme north from October to May. Persistent fog can be a maritime hazard from May to September, as can hurricanes north of the equator (May to December).

The United States' southeast coast has a long history of shipwrecks due to its many shoals and reefs. The Virginia and North Carolina coasts were particularly dangerous.

The Bermuda Triangle is popularly believed to be the site of numerous aviation and shipping incidents because of unexplained and supposedly mysterious causes, but Coast Guard records do not support this belief.

Hurricanes are also a natural hazard in the Atlantic, but mainly in the northern part of the ocean, rarely tropical cyclones form in the southern parts. Hurricanes usually form between 1 June and 30 November of every year.

Plate tectonics[edit]

The break-up of Pangaea resulted in the opening of the Atlantic Ocean in three stages

Central Atlantic[edit]

The break-up of Pangaea began in the Central Atlantic, between North America and Northwest Africa, where rift basins opened during 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.[37]

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 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.[38] 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 4.5×106 km2 (1.7×106 sq mi) of which 2.5×106 km2 (9.7×105 sq mi) covered what is now northern and central Brazil.[39]

Northern Atlantic[edit]

Geologically the Northern Atlantic is the area delimited to the south by two conjugate margins, Newfoundland and Iberia, and to the north by the Arctic Eurasian Basin. The opening of the Northern Atlantic closely followed the margins of its predecessor, the Iapetus Ocean, and spread from the Central Atlantic in six stages: IberiaNewfoundland, Porcupine–North America, Eurasia–Greenland, Eurasia–North America. Active and inactive spreading systems in this area are marked by the interaction with the Iceland hotspot.[40]

South Atlantic[edit]

West Gondwana (South America and Africa) broke up in the Early Cretaceous to form the South Atlantic. The apparent fit between the coastlines of the two continents was noted on the first maps that included the South Atlantic and it was also the subject of the first computer-assisted plate tectonic reconstructions in 1965.[41][42] This magnificent fit, however, has since then proven problematic and later reconstructions have introduced various deformation zones along the shorelines to accommodate the northward-propagating break-up.[41] Intra-continental rifts and deformations have also been introduced to subdivide both continental plates into sub-plates.[43]

Geologically the South Atlantic can be divided into four segments: Equatorial segment, from 10°N to the Romanche Fracture Zone (RFZ);; Central segment, from RFZ to Florianopolis Fracture Zone (FFZ, north of Walvis Ridge and Rio Grande Rise); Southern segment, from FFZ to the Agulhas-Falkland Fracture Zone (AFFZ); and Falkland segment, south of AFFZ.[44]

In the southern segment the Early Cretaceous (133–130 Ma) intensive magmatism of the Paraná–Etendeka Large Igneous Province produced by the Tristan hotspot resulted in an estimated volume of 1.5×106 to 2.0×106 km3 (3.6×105 to 4.8×105 cu mi). It covered an area of 1.2×106 to 1.6×106 km2 (4.6×105 to 6.2×105 sq mi) in Brazil, Paraguay, and Uruguay and 0.8×105 km2 (3.1×104 sq mi) in Africa. Dyke swarms in Brazil, Angola, eastern Paraguay, and Namibia, however, suggest the LIP originally covered a much larger area and also indicate failed rifts in all these areas. Associated offshore basaltic flows reach as far south as the Falkland Islands and South Africa. Traces of magmatism in both offshore and onshore basins in the central and southern segments have been dated to 147–49 Ma with two peaks between 143–121 Ma and 90–60 Ma.[44]

In the Falkland segment rifting began with dextral movements between the Patagonia and Colorado sub-plates between the Early Jurassic (190 Ma) and the Early Cretaceous (126.7 Ma). Around 150 Ma sea-floor spreading propagated northward into the southern segment. No later than 130 Ma rifting had reached the Walvis Ridge–Rio Grande Rise.[43]

In the central segment rifting started to break Africa in two by opening the Benue Trough around 118 Ma. Rifting in the central segment, however, coincided with the Cretaceous Normal Superchron (also known as the Cretaceous quiet period), a 40 Ma period without magnetic reversals, which makes it difficult to date sea-floor spreading in this segment.[43]

The equatorial segment is the last phase of the break-up, but, because it is located on the Equator, magnetic anomalies cannot be used for dating. Various estimates date the propagation of sea-floor spreading in this segment to the period 120–96 Ma. This final stage, nevertheless, coincided with or resulted in the end of continental extension in Africa.[43]

Closure of the Atlantic[edit]

An embryonic subduction margin is potentially developing west of Gibraltar. The Gibraltar Arc in the western Mediterranean is migrating westward into the Central Atlantic where it joins the converging African and Eurasian plates. These three tectonic forces are potentially developing into a new subduction system in the eastern Atlantic Basin. Meanwhile the Scotia Arc and Caribbean Plate in the western Atlantic Basin are eastward-propagating subduction system that might, together with the Gibraltar system, represent the beginning of the closure of the Atlantic Ocean and the end of a Wilson Cycle.[45]


The Norsemen, the Portuguese and the Spanish were the first to explore and to cross it systematically, from Europe to the Americas, as well as to its islands and archipelagos, and from the North Atlantic to the South Atlantic. It was after the voyages of Christopher Columbus in 1492, at the service of Castile (later Spain), that the Americas became well known in Europe and European exploration rapidly accelerated, leading to many new trade routes and the colonization of the Americas.[4]

As a result, the Atlantic became and remains the major artery between Europe and the Americas (known as transatlantic trade). Scientific explorations include the Challenger expedition, the German Meteor expedition, Columbia University's Lamont-Doherty Earth Observatory and the United States Navy Hydrographic Office.[4]


Intended to unite the so-called Western World, the proposed Transatlantic Trade and Investment Partnership, and its possible future expansion, highlights the global importance of trade across the North Atlantic to the exclusion of the continents bordering the South Atlantic.

The Atlantic has contributed significantly to the development and economy of surrounding countries. Besides major transatlantic transportation and communication routes, the Atlantic offers abundant petroleum deposits in the sedimentary rocks of the continental shelves. The Atlantic hosts the world's richest fishing resources, especially in the waters covering the shelves. The major fish are cod, haddock, hake, herring, and mackerel.[4]

The most productive areas include the Grand Banks of Newfoundland, the Nova Scotia shelf, Georges Bank off Cape Cod, the Bahama Banks, the waters around Iceland, the Irish Sea, the Dogger Bank of the North Sea, and the Falkland Banks. Eel, lobster, and whales appear in great quantities. Various international treaties attempt to reduce pollution caused by environmental threats such as oil spills, marine debris, and the incineration of toxic wastes at sea.[4]

The Atlantic harbours petroleum and gas fields, fish, marine mammals (seals and whales), sand and gravel aggregates, placer deposits, polymetallic nodules, and precious stones. Gold deposits are a mile or two under water on the ocean floor, however the deposits are also encased in rock that must be mined through. Currently, there is no cost-effective way to mine or extract gold from the ocean to make a profit.[46]

Environmental issues[edit]

Oceanic trash strewn over the beaches of Inaccessible Island in the South Atlantic

Endangered marine species include the manatee, seals, sea lions, turtles, and whales. Drift net fishing can kill dolphins, albatrosses and other seabirds (petrels, auks), hastening the fish stock decline and contributing to international disputes.[47] Municipal pollution comes from the eastern United States, southern Brazil, and eastern Argentina; oil pollution in the Caribbean Sea, Gulf of Mexico, Lake Maracaibo, Mediterranean Sea, and North Sea; and industrial waste and municipal sewage pollution in the Baltic Sea, North Sea, and Mediterranean Sea.

In 2005, there was some concern that warm northern European currents were slowing down.[48]

On 7 June 2006, Florida's wildlife commission voted to take the manatee off the state's endangered species list. Some environmentalists worry that this could erode safeguards for the popular sea creature.

Marine pollution is a generic term for the entry into the ocean of potentially hazardous chemicals or particles. The biggest culprits are rivers and with them many agriculture fertilizer chemicals as well as livestock and human waste. The excess of oxygen-depleting chemicals leads to hypoxia and the creation of a dead zone.[49]

Marine debris, which is also known as marine litter, describes human-created waste floating in a body of water. Oceanic debris tends to accumulate at the centre of gyres and coastlines, frequently washing aground where it is known as beach litter.

See also[edit]



  1. ^ a b c d e f Eakins & Sharman 2010
  2. ^ a b c CIA World Factbook: Atlantic Ocean
  3. ^ NOAA: How big is the Atlantic Ocean?
  4. ^ a b c d e f g h i j k l m n U.S. Navy 2001
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External links[edit]

Coordinates: 0°N 30°W / 0°N 30°W / 0; -30