[75] Furthermore, colonisation models based on mtDNA, yDNA, and atDNA data respectively support neither the "blitzkrieg" nor the "three-wave" hypotheses but they also deliver mutually ambiguous results. Furthermore, it is clear from statistical analyses of annual tropical cyclones that these changes do not display multidecadal cyclicity. The earliest exploitation, however, took place on the now submerged shelves, and most settlements now excavated were then located several kilometers from these shelves. 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. The most important species in the area, Gulf menhaden, reached a million tons in the mid-1980s but only half a million tons in 2013 and is now considered fully fished. Our sailing weather forecasts are derived using data from the most trusted and reliable weather models available. Climatic zones vary with latitude; the warmest zones stretch across the Atlantic north of the equator. The MAR reaches above 2,000 m (6,600 ft) 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. For their own safety, the crew jettisoned two nuclear bombs, which were never recovered. [35], There are five intermediate waters: four low-salinity waters formed at subpolar latitudes and one high-salinity formed through evaporation. 'Sea of Atlantis') and in The Histories of Herodotus around 450 BC (Hdt. [41] Météo des plages de l'océan Atlantique La façade Atlantique dispose en majorité de grandes plages de sable fin, souvent bien animées tout au long de l'année. [6], Every winter, the Icelandic Low produces frequent storms. Horse mackerel and hake are the most important species, together representing almost half of the landings. Currently, there is no cost-effective way to mine or extract gold from the ocean to make a profit. [37], 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. Correspondingly, the extent and number of oceans and seas vary. Limited data makes the state of redfishes and deep-water species difficult to assess but most likely they remain vulnerable to overfishing. [56]. [85], 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. [77] Arctic cod reached its lowest levels in the 1960s–1980s but is now recovered. The most productive areas include the Grand Banks of Newfoundland, the Scotian Shelf, Georges Bank off Cape Cod, the Bahama Banks, the waters around Iceland, the Irish Sea, the Bay of Fundy, the Dogger Bank of the North Sea, and the Falkland Banks. Large quantities of basalt erupted at this time period are found on Baffin Island, Greenland, the Faroe Islands, and Scotland, with ash falls in Western Europe acting as a stratigraphic marker. Stocks of northern shrimp and Norwegian lobster are in good condition. [61], In the central segment rifting started to break Africa in two by opening the Benue Trough around 118 Ma. Ocean currents influence the climate by transporting warm and cold waters to other regions. 211):[7] Atlantikôi pelágei (Greek: Ἀτλαντικῷ πελάγει; English: 'the Atlantic sea'; etym. 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. Geologists distinguish two magmatic phases. This final stage, nevertheless, coincided with or resulted in the end of continental extension in Africa. The ice season is longer in the polar regions, but there is little shipping in those areas. Spreading began opening the Labrador Sea around 61 million years ago, continuing until 36 million years ago. 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. A. R. 1. While their middens resemble 12–11 kya-old Late Stone Age (LSA) middens found on every inhabited continent, the 50–45 kya-old Enkapune Ya Muto in Kenya probably represents the oldest traces of the first modern humans to disperse out of Africa. In the southeast, the Atlantic merges into the Indian Ocean. [86], In the North-West Atlantic landings have decreased from 4.2 million tons in the early 1970s to 1.9 million tons in 2013. [67], Mitochondrial DNA (mtDNA) studies indicate that 80–60,000 years ago a major demographic expansion within Africa, derived from a single, small population, coincided with the emergence of behavioral complexity and the rapid MIS 5–4 environmental changes. Along its path across Earth the composition of the NADW is affected by other water masses, especially Antarctic Bottom Water and Mediterranean Overflow Water. Iceland was initially settled 865–930 CE following a warm period when winter temperatures hovered around 2 °C (36 °F) which made farming favorable at high latitudes. 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. 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).[25]. North Atlantic Deep Water flows southward below the thermocline of the subtropical gyre. A small population of modern humans — probably fewer than a thousand reproducing individuals — survived glacial maxima by exploring the high diversity offered by these Palaeo-Agulhas plains. The sea snail perlemoen abalone is targeted by illegal fishing and remain overfished. In the middle latitudes, the area of maximum temperature variations, values may vary by 7–8 °C (13–14 °F). Maximum salinity values occur at about 25° north and south, in subtropical regions with low rainfall and high evaporation. [30], The remainder of the ridge was discovered in the 1920s by the German Meteor expedition using echo-sounding equipment. Oceanic debris tends to accumulate at the center of gyres and coastlines, frequently washing aground where it is known as beach litter. Température de l'eau de l'océan atlantique en janvier - Minimum : 33°F/Maximum : 84°F Température de l'eau de l'océan atlantique en février - Minimum : 30°F/Maximum : 85°F Température de l'eau de l'océan atlantique en mars - Minimum : 30°F/Maximum : 85°F Température de l'eau de l'océan atlantique en avril - Minimum : 33°F/Maximum : 85°F Température de l'eau de l'océan atlantique en mai - … ", "The geological history of the North Atlantic Ocean", Atlantic Continental Shelf and Slope of the United States, "Problems and Prospects for the Pelagic Driftnet", "Huge Garbage Patch Found in Atlantic Too", Armed Forces Radiobiology Research Institute, "The rise of Europe: Atlantic trade, institutional change and economic growth", "All roads lead to home: panmixia of European eel in the Sargasso Sea", "The Ysterfontein 1 Middle Stone Age rock shelter and the evolution of coastal foraging", "Archaeology of the continental shelf: marine resources, submerged landscapes and underwater archaeology", "Zircon U-Pb geochronology links the end-Triassic extinction with the Central Atlantic Magmatic Province", "Decadal variability of subpolar gyre transport and its reverberation in the North Atlantic overturning", "Exploring the analogy between modern trafficking in humans and the trans-Atlantic slave trade", "Slowing of the Atlantic meridional overturning circulation at 25 N", "The fit of the continents around the Atlantic", "Are subduction zones invading the Atlantic? It is known to separate the "Old World" from the "New World" in European perception of the World. Between the 15th century and 1888, when Brazil became the last part of the Americas to end the slave trade, an estimated ten million Africans were exported as slaves, most of them destined for agricultural labour. [6] Associated offshore basaltic flows reach as far south as the Falkland Islands and South Africa. [6], The Gulf Stream and its northern extension towards Europe, the North Atlantic Drift is thought to have at least some influence on climate. Meanwhile, the Scotia Arc and Caribbean Plate in the western Atlantic Basin are eastward-propagating subduction systems that might, together with the Gibraltar system, represent the beginning of the closure of the Atlantic Ocean and the final stage of the Atlantic Wilson cycle. "[73] Others later proposed a "three-wave" migration over the Bering Land Bridge. [38], North of the North Atlantic Gyre, the cyclonic North Atlantic Subpolar Gyre plays a key role in climate variability. [68] During the Last Glacial Maximum (LGM) 20,000 years ago humans had to abandon their initial settlements along the European North Atlantic coast and retreat to the Mediterranean. Almost half of the stocks are fished at biologically unsustainable levels. The biggest culprits are rivers and with them many agriculture fertilizer chemicals as well as livestock and human waste. Une équipe de chercheurs a récemment fourni la réponse grâce à l’analyse détaillée de sédiments lacustres. [43], Other species endemic to the Sargasso Sea include the sargassum fish, a predator with algae-like appendages which hovers motionless among the Sargassum. The Rockall Trough opened between 105 and 84 million years ago although along the rift failed along with one leading into the Bay of Biscay. [28] 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.[29]. Total catches have been fluctuating since the 1970s; reaching 3.9 million tons in 2013 or slightly less than the peak production in 2010. This involved little guesswork because the idea of sonar is straight forward with pulses being sent from the vessel, which bounce off the ocean floor, then return to the vessel. 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 the Falkland Islands. [6], Scientific explorations of the Atlantic include the Challenger expedition, the German Meteor expedition, Columbia University's Lamont-Doherty Earth Observatory and the United States Navy Hydrographic Office.[6]. [17], The Atlantic has irregular coasts indented by numerous bays, gulfs and seas. ", "The great American schism: divergence of marine organisms after the rise of the Central American Isthmus", "On the Movements of the North Atlantic Subpolar Front in the Preinstrumental Past", "Coastal South Africa and the Coevolution of the Modern Human Lineage and the Coastal Adaptation", "Stone age people in a changing South African greater Cape Floristic Region", "Stability of the thermohaline circulation under millennial CO2 forcing and two alternative controls on Atlantic salinity", "The Discovery of America: The first Americans may have swept the Western Hemisphere and decimated its fauna within 1000 years", "Extensive 200-million-year-old continental flood basalts of the Central Atlantic Magmatic Province", "Why did modern human populations disperse from Africa ca. [86], In the South-East Atlantic catches have decreased from 3.3 million tons in the early 1970s to 1.3 million tons in 2013. Atlantic Ocean, body of salt water covering about one-fifth of Earth’s surface and separating the continents of Europe and Africa to the east from those of North and South America to the west. 34–30 Ma a deeper seaway developed, followed by an Eocene–Oligocene climatic deterioration and the growth of the Antarctic ice sheet. The Laurentian Abyss is found off the eastern coast of Canada. The excess of oxygen-depleting chemicals leads to hypoxia and the creation of a dead zone. 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. [32] The deep ocean floor is thought to be fairly flat with occasional deeps, abyssal plains, trenches, seamounts, basins, plateaus, canyons, and some guyots. The 20° East meridian, running south from Cape Agulhas to Antarctica defines its border. 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. [26] 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. Its eastern portion includes eddying branches of the North Atlantic Current which transport warm, saline waters from the subtropics to the north-eastern Atlantic. [44], The location of the spawning ground for European eels remained unknown for decades. [43] The origin of the Sargasso fauna and flora remained enigmatic for centuries. [69] The European coasts of the North Atlantic were permanently populated about 9–8.5 thousand years ago. [19][20], The bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge (MAR). [6], The oceans are the major source of the atmospheric moisture that is obtained through evaporation. In 1973 late American geoscientist Paul S. Martin proposed a "blitzkrieg" colonization of the Americas by which Clovis hunters migrated into North America around 13,000 years ago in a single wave through an ice-free corridor in the ice sheet and "spread southward explosively, briefly attaining a density sufficiently large to overkill much of their prey. The most important species, the Argentine shortfin squid, which reached half a million tons in 2013 or half the peak value, is considered fully fished to overfished. 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. [88], Marine pollution is a generic term for the entry into the ocean of potentially hazardous chemicals or particles. The NADW, in its turn, feeds the meridional overturning circulation (MOC), the northward heat transport of which is threatened by anthropogenic climate change. Active and inactive spreading systems in this area are marked by the interaction with the Iceland hotspot. Selon les chercheurs, ces résultats montrent que le réchauffement récent de la surface de l’océan Atlantique est sans précédent. [49], In many places, the continental shelf and continental slope are covered in thick sedimentary layers. 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. Ocean currents such as the Gulf Stream transport eel larvae from the Sargasso Sea to foraging areas in North America, Europe, and Northern Africa. [11] 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. The measurements for the water temperature in Fort Lauderdale, Florida are provided by the daily satellite readings provided by the NOAA. 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 the western Atlantic and South Sandwich Trench (8,264 m or 27,113 ft) in the South Atlantic. [6], 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. The Landnámabók (Book of Settlement) records disastrous famines during the first century of settlement — "men ate foxes and ravens" and "the old and helpless were killed and thrown over cliffs" — and by the early 1200s hay had to be abandoned for short-season crops such as barley. ", "Why doesn't the South Atlantic Ocean experience tropical cyclones? [46], Climate is influenced by the temperatures of the surface waters and water currents as well as winds. 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 where it migrated over Sicily to the Central Atlantic where it evolved into modern species of the Sargasso Sea. [83], Trans-Atlantic trade also resulted in increasing urbanization: in European countries facing the Atlantic, urbanization grew from 8% in 1300, 10.1% in 1500, to 24.5% in 1850; in other European countries from 10% in 1300, 11.4% in 1500, to 17% in 1850. The third group, "continuously increasing trend since 1950", is only found in the Indian Ocean and Western Pacific. 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 millions of years. Carte des zones de prévisions maritimes et alertes en vigueur. Carte de la température des eaux de surface de l’océan Atlantique (secteur Golfe du Méxique/ Caraïbes) en mai 2015 (© 2015 by Ocean Remote Sensing Group, Johns Hopkins University Applied Physics Laboratory). La température de l'océan Atlantique, sur les côtes canadiennes, continue de grimper, selon la plus récente étude sur les conditions océanographiques de Pêches et Océans Canada. [76] A proposed route across the Pacific to South America could explain early South American finds and another hypothesis proposes a northern path, through the Canadian Arctic and down the North American Atlantic coast. 1.202.4): Atlantis thalassa (Greek: Ἀτλαντὶς θάλασσα; English: 'Sea of Atlantis' or 'the Atlantis sea'[8]) 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. 50 kya-old, deeply stratified shell middens found in Ysterfontein on the western coast of South Africa are associated with the Middle Stone Age (MSA). Colonialism evolved as part of the Trans-Atlantic trade, but this trade also strengthened the position of merchant groups at the expense of monarchs. The term dates to as early as 1640, first appearing in print in 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.[14][15][16]. [59] Intra-continental rifts and deformations have also been introduced to subdivide both continental plates into sub-plates. Accédez à la page que vous souhaitez ajouter à vos favoris, ouvrez le menu des raccourcis météo et cliquez sur le bouton « Ajouter aux raccourcis »; Le nom de la page sera affiché dans la fenêtre « Ajouter cette page ». La figure 4.3 représente la distribution moyenne de la température sur une coupe de l'océan Atlantique Ouest.Cette figure illustre bien le confinement des températures élevées dans la partie supérieure de l'océan. Recovery plans for cod, sole, and plaice have reduced mortality in these species. 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%). The earliest evidence for the complex behavior associated with this behavioral modernity has been found in the Greater Cape Floristic Region (GCFR) along the coast of South Africa. [27], 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. [61], About 50 Ma the opening of the Drake Passage resulted from a change in the motions and separation rate of the South American and Antarctic plates. [61], 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. A USAF C-124 aircraft from Dover Air Force Base, Delaware was carrying three nuclear bombs over the Atlantic Ocean when it experienced a loss of power. The slave trade was officially abolished in the British Empire and the United States in 1808, and slavery itself was abolished in the British Empire in 1838 and in the United States in 1865 after the Civil War. For other uses, see, Extent of the Atlantic Ocean according to the 2002 IHO definition, excluding, For complete lists of marginal seas and borders of the Atlantic, see, For the extent of the Southern Ocean, see, For a list of fracture zones in the Atlantic, see, Opening of the Central Atlantic 200-170 Ma, Sebastian A. Gerlach "Marine Pollution", Springer, Berlin (1975), List of bordering countries (not drainage basin), Landscape of the Pico Island Vineyard Culture, Pre-Columbian trans-oceanic contact theories, List of notable crossings of the Atlantic Ocean, collapse of the Atlantic northwest cod fishery, List of countries and territories bordering the Atlantic Ocean, "An inside look at the first solo trip to the deepest point of the Atlantic", "Ἀτλαντίς, DGE Diccionario Griego-Español", "World Map / World Atlas / Atlas of the World Including Geography Facts and Flags - WorldAtlas.com", World Heritage Centre: Mid-Atlantic Ridge, The Geological Society: Mid-Atlantic Ridge, Marchal, Waelbroeck & Colin de Verdière 2016, "Do Baby Eels Use Magnetic Maps to Hitch a Ride on the Gulf Stream? 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. In the 1953 definition it extends south to Antarctica, while in later maps it is bounded at the 60° parallel by the Southern Ocean. [63], An embryonic subduction margin is potentially developing west of Gibraltar. [50], 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. 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. 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. England, France, and the Dutch Republic enviously watched the Spanish and Portuguese wealth grow and allied themselves with pirates such as Henry Mainwaring and Alexandre Exquemelin. [10] 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. [95], Ocean between Europe, Africa and the Americas, "Atlantic", "North Atlantic", "South Atlantic", and "Atlantic Basin" redirect here. Maximum temperatures occur north of the equator, and minimum values are found in the polar regions. 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. In the South Atlantic the Walvis Ridge and Rio Grande Rise form barriers to ocean currents. The second-largest ocean on Earth, the Atlantic drives our weather patterns, including hurricanes, and is home to many species from sea turtles to dolphins.