The Atlantic Ocean is the second largest ocean in the world with a total area of ​​approximately 106,460,000 square kilometers (41.1 million square miles). It covers about 20 percent of the Earth's surface and about 29 percent of its surface area. This separates the "Old World" from the "New World".
The Atlantic Ocean occupies an elongated S-shaped basin that extends longitudinally between Eurasia and Africa to the east, and America to the west. As one component of the interconnected global ocean, it connects north to the Arctic Ocean, to the Pacific Ocean in the southwest, the Indian Ocean to the southeast, and the Southern Ocean to the south (another definition describing the Atlantic as extending south into Antarctica). The Equatorial Counter Current divides it into North Atlantic Ocean and South Atlantic Ocean about 8 Â ° N.
Atlantic scientific explorations include the Challenger expedition, the German Meteor expedition, the Lamont-Doherty Earth Observatory of Columbia University, and the United States Navy Hydrographic Office.
Video Atlantic Ocean
Etimologi
The oldest mention of the "Atlantic" of the sea originated from Stesichorus around the middle of the sixth century BC (Sch. AR 1. 211): Atlantikoi pelÃÆ'¡gei (Greek: ????????? The Atlantis Sea and the Atlantis of the Sea and The Histories of Herodotus about 450 BC (Hdt: 1202.4): Atlantis thalassa (Greek: ??????????????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????????? became part of the sea that surrounds all the land, so on the one hand it refers to Atlas, the Titan in Greek mythology, which supports the heavens and which later emerges as a face image on the Medieval map and also lends its name to the modern atlas. for the early Greek sailors and in Ancient Greek mythology literature such as the Iliad and Odyssey, the seas encompassing all these are known as Oceanus, the giant river that encompasses the world, unlike the sea shrink ups known by the Greeks: the Mediterranean Sea and the Black Sea. Instead, the term "Atlantic" was originally referred to specifically for the Atlas Mountains in Morocco and the open seas of the Strait of Gibraltar and the coast of North Africa. The Greek word
The term "Aethiopian Ocean", derived from Ancient Ethiopia, was applied to the South Atlantic until the mid-19th century. During the Age of the Invention, the Atlantic was also known by the English cartographer as Great Western Ocean .
Maps Atlantic Ocean
Extents and data
The International Hydrographic Organization (IHO) defined the sea and ocean boundaries in 1953, 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 breadth and number of oceans and seas vary.
The Atlantic Ocean is bordered in the west by North and South America. It connects to the Arctic Sea through Denmark Strait, Greenland Sea, Norwegian Sea, and Barents Sea. To the east, the right oceanic boundary is Europe: the Strait of Gibraltar (where it connects with the Mediterranean Sea - one of its marginal oceans - and, in turn, the Black Sea, both also touching Asia) and Africa.
In the southeast, the Atlantic blends with the Indian Ocean. East Meridian 20 °, running south from Cape Agulhas to Antarctica defines its borders. In the 1953 definition it extends southward to Antarctica, while on the map then it is limited to parallel 60 Â ° by the Southern Ocean.
Atlantic has an irregular beach that is infested by many bays, bays, and seas. These include the Baltic Sea, the Black Sea, the Caribbean Sea, the Davis Strait, the Danish Strait, part of the Drake Strait, the Gulf of Mexico, the Labrador Sea, the Mediterranean Sea, the North Sea, the Norwegian Sea, almost all the Scotia Sea, and other tributaries of water bodies. Including the marginal ocean of the Atlantic coastline measures 111,866 km (69,510 mi) compared to 135,663 km (84,297 mi) for the Pacific.
Including its marginal ocean, the Atlantic covers an area of ​​106,460,000 km <2 (41.1 million sq. Mi) or 23.5% of the global oceans and has a volume of 310,410,900 km 3 (74,471. 500 cuÃ, mi) or 23.3% of the total ocean volume on earth. Not including the marginal ocean, the Atlantic covers 81,760,000 km 2 (31,570,000 sqà mi) and has a volume of 305,811,900 km 3 (73,368,200 mu). The North Atlantic includes 41.490.000 km 2 (16,020,000 sqÃ, mi) (11.5%) and the South Atlantic 40.270.000 km 2 (15.55 million sq. mi) (11.1%). The average depth is 3,646 m (11,962 ft) and the maximum depth, Milwaukee Deep in the Puerto Rico Tram, is 8,486 m (27,841 ft).
Bathymetry
The Atlantic Batimetry is dominated by the underwater mountains called Mid-Atlantic Ridge (MAR). It runs from 87 ° N or 300 km (190 miles) south of the Arctic to the subantarctic Bouvet Island at 42 ° S.
Mid-Atlantic Ridge
MAR divided the Atlantic longitudinal into two parts, in each series of sediments separated by secondary mountains, horizontally. MAR reaches above 2,000 m (6,600 ft) throughout most of its length, but is disturbed by larger transformation errors in two places: Parit Romanche near the Equator and Gibbs Fracture Zone at 53 ° N. MAR is a barrier to ground water, but at these two changes, deep water currents can pass from one side to the other.
MAR rises 2-3 km (1.2-1.9 million) above the surrounding seafloor and its cracked valley is a distinct boundary between the North American and Eurasian plates in the North Atlantic and the South American and African plates in the South Atlantic. MAR produces basaltic volcanoes in EyjafjallajÃÆ'¶kull, Iceland, and lava cushions on the ocean floor. The water depth at the top 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 deeper.
MAR is truncated by two perpendicular protrusions: the Azores-Gibraltar Transform Fault, the boundary between the Nubian and Eurasian plate, cuts the MAR in the Azores Triple Junction, on both sides of the Azores plate, near 40 Â ° N. A clearer and nameless boundary between the North American and South American plates, cutting the MAR close to or just north of the Fractle Zone of the Fifteenth-Twenties, approximately at 16 ° C.
In the 1870s, the Challenger expedition discovered what parts are now known as the Middle Atlantic Spine, or:
A high ridge rises to an average height of about 1,900 fathoms [3,500m]; 11.400Ã, ft] beneath the surface across the North and South Atlantic basins in the direction of the meridians of Cape Farewell, perhaps the southernmost of at least as the Gough Island, following the outline of the beaches of the Old World and the New World.
The rest of the ridge was discovered in 1920 by a German Meteor expedition using an audible echo apparatus. MAR exploration in the 1950s led to the general acceptability of seafloor deployment and tectonic plates.
Most of the MAR flows underwater but where it reaches the surface it has produced volcanic islands. While nine of them are collectively nominated as World Heritage Sites for their geological value, four of them are considered "Universal Extraordinary Value" based on their cultural and natural criteria: ÃÆ'žingvellir, Iceland; View of Pico Island Wine Garden, Portugal; Gough and Inaccessible Islands, United Kingdom; and the Atlantic Islands of Brazil: Fernando de Noronha and Atoll das Rocas Reserves, Brazil.
Ocean floor
The continental shelf in the Atlantic is vast in Newfoundland, southernmost South America, and north-eastern Europe. In western Atlanticic carbonate platforms dominate large areas, such as Blake Plateau and Bermuda Rise. The Atlantic is surrounded by passive margins except in some locations where active margins form deep trenches: Puerto Rico Trench (8,414 m or 27,605 ft maximum depth) in the western Pacific and South Trench Sandwich (8,264 m or 27,113 ft) in the South Atlantic. There are many submarine valleys in northeastern North America, Western Europe, and northwestern Africa. Some of these gorges stretch as long as the continents rise and further into the abyssal plains as deep sea channels.
In 1922 the historic moment in cartography and oceanography took place. USS Stewart uses Sonic Depth Finder to draw a continuous map over the Atlantic bed. This involves a bit of a guess because the sonar idea is straight forward with a pulse sent from the ship, which bounces off the seabed, then returns to the ship. The deep ocean floor is considered quite flat with occasional depths, abyssal plains, moats, sea mountains, basins, highlands, canyons, and some jokes. Various shelves along the periphery of the continent cover about 11% of the lower topography with several channels in cutting across the continent.
The average depth between 60 Â ° C and 60 ° S is 3,730 m (12,240 ft), or close to the global average, with a capital depth of between 4,000 and 5,000 m (13,000 and 16,000 ft).
In the South Atlantic, Walvis Ridge and the Rio Grande Rise are blocking ocean currents. The Laurentian Abyss is found off the east coast of Canada.
Water Characteristics
The surface water temperature, which varies with latitude, current system, and season and reflects the distribution of solar energy in latitudinal manner, ranging from below -2 Â ° C (28 Â ° F) to over 30 ° C (86 Â ° F). The maximum temperature occurs north of the equator, and the minimum value is found in the polar regions. In the middle latitudes, the area of ​​maximum temperature variation, its value may vary from 7 to 8 Â ° C (13-14 Â ° F).
From October to June the surface is usually covered by sea ice in the Labrador Sea, the Danish Strait, and the Baltic Sea.
The Coriolis effect circulates the North Atlantic water in a clockwise direction, while the South Atlantic water circulates counter-clockwise. The southern waves in the Atlantic Ocean are semi-diurnal; ie, two high pairs occur during every lunar 24 hours. In latitudes above 40 Â ° North, some east-west oscillations, known as North Atlantic oscillations, occur.
Salinity
On average, the Atlantic is the most salty main ocean; the salinity of surface water in open sea ranges from 33 to 37 parts per thousand (3.3 - 3.7%) based on mass and varies with latitude and season. Evaporation, precipitation, river flow and sea ice melt affect the value of surface salinity. Although the lowest salinity value is just north of the equator (due to high tropical rainfall), generally the lowest values ​​are at high latitudes and along the coast where large rivers enter. The maximum salinity value occurs at about 25 ° north and south, in subtropics with low rainfall and high evaporation.
The high surface salinity in the Atlantic, where the Atlantic thermohaline circulation is dependent, is maintained by two processes: Agulhas Leakage/Rings, which brings salt water to the Southern Indian Ocean, and the subtropical "Atmospheric Bridge". Atlantic waters and export them to the Pacific.
Water masses
The Atlantic Ocean consists of four major upper water masses with different temperatures and salinity. The Atlantic Subarctic Sea Water in the northern most northern part of the Atlantic is the source for Submediate Intermediate Water and North Atlantic Intermediate Water. Central North Atlantic Water can be divided into the Central Central Sea portion of the East and West Atlantic as the western part is heavily influenced by the Gulf Stream and therefore the top layer is closer to the subpolar of fresh water intermediates. East water is saltier due to its proximity to the Mediterranean Water. Central North Atlantic Water flows to the South Central Atlantic Water at 15 Â ° N.
There are five medium waters: four low-salinity waters formed in subpolar latitudes and one high salinity formed by evaporation. Arctic Intermediate Water, flowing from the north to become a source for Deep Water Deep Atlantic south of Greenland-Scotland sill. Both waters between have different salinity in the west and east basin. Various salinity in the North Atlantic is attributed to the northern subtropical gyre asymmetry and a large number of contributions from various sources: Labrador Sea, Norwegian Sea-Greenland, Mediterranean and South Atlantic Water.
The North Atlantic Water (NADW) is a complex of four water masses, two of which are formed by deep convection in the open sea - Classical and Upper Labrador Sea Water - and two formed from the entry of solid water across Greenland - Iceland-Scotland sillÃ, - Denmark Strait and Iceland-Scotland Abundant Water. Along its path across the Earth, the composition of NADW is influenced by other water masses, especially the Antarctic Bottom Water and Mediterranean Water Abundance. NADW is fed by a shallow warm shallow stream to the north of the North Atlantic that is responsible for the warm climate of anomalies in Europe. Changes in the formation of NADW have been linked to global climate change in the past. Because artificial substances are introduced into the environment, the NADW path can be traced along its path by measuring tritium and radiocarbon from nuclear weapons tests in the 1960s and CFCs.
Gyres
The North Atlantic Coast is clockwise in the North Atlantic, and Atlantic Atlantic clockwise counter-cold water appears in the South Atlantic.
In the North Atlantic, the surface circulation is dominated by three interconnected currents: Gulf currents flowing north-east from the coast of North America on Cape Hatteras; North Atlantic Stream, a branch of the Gulf Stream that flows north from the Grand Banks; and the Subpolar Front, an extension of the North Atlantic Stream, a vast area, vaguely separating the subtropical gyre from the subpolar gyre. This current system transports warm water to the North Atlantic, without which temperatures in the North Atlantic and Europe will drop dramatically.
North Atlantic North Pilin, North Atlantic brackets Subpolar cyclones play a key role in climate variability. It is governed by ocean currents from marginal marine and regional topography, rather than being controlled by wind, both at sea level and at sea level. Subpolar gyre forms an important part of the global thermohalin circulation. Its eastern part includes the eddy branches of the North Atlantic Stream that carry warm subtropical salt water to the northeast Atlantic. There the water is cooled during the winter and forms a backflow that joins along the slopes of the eastern continent of Greenland where they form an intense (40-50 Sv) current that flows around the continental boundary of the Labrador Sea. One-third of this water becomes part of the interior of the North Atlantic Deep Deep Water (NADW). The NADW, in turn, feeds meridional overturning circulation (MOC), heat transport to the north threatened by anthropogenic climate change. The large variations in subpolar pies on a decade-old scale, linked to North Atlantic oscillations, are especially pronounced in Labrador Sea Water, the top layer of MOC.
The South Atlantic is dominated by the southern anti-cyclone subtropical twist. Central South Atlantic Water comes from this gyre, while Antarctic Intermediate Water comes from the upper layers of the circumpolar region, near the Drake Strait and the Falkland Islands. These two currents receive some contributions from the Indian Ocean. On the east coast of Africa, the small Angolian Cyclone trees lie in a large subtropical gyre. The southern subtropical twist is partly covered by the wind-induced Ekman layer. Gyre residence time is 4.4-8.5 years. The North Atlantic Sea water flows south below the subtropical spiral thermocline.
Sargasso Sea
The Sargasso Sea in the western North Atlantic can be defined as the area in which two species of Sargassum S. Fluitans and natans ) float, an area of ​​4,000 km ( 2,500 miles) and is surrounded by Gulf Stream, North Atlantic Drift and North Equatorial Current. This seaweed population may have originated from Tertiary ancestors on the coast of Europe from Tethys Ocean before and, if so, defended itself with vegetative growth, floating in the ocean for millions of years.
Other species of endemic Sargasso Sea include sargassum fish, predators with complementary algae such as floating motionlessly between Sargassum . The same fish fossils have been found in the fossil bays of Tethys Ocean before, in what is now the Carpathian region, which is similar to the Sargasso Sea. It is possible that populations in the Sargasso Sea migrate to the Atlantic as Tethys closed at the end of the Miocene around 17 Ma. The origin of the fauna and flora of Sargasso remains mysterious for centuries. The fossils found in the Carpathians in the mid-20th century, often called "quasi-Sargasso collections", ultimately show that this collection originated from the Carpathian Basin from which it migrated to Sicily in the Middle Atlantic where it evolved into the modern species of Sargasso Sea.
Spawning sites for European eel remain unknown for decades. At the beginning of the 19th century it was discovered that the southern Sargasso Sea was the breeding ground for European and American eels and that the first migrated over 5,000 km (3,100 miles) and the latter 2,000 km (1,200 mi). Ocean currents like the Bay of Grasshopper transport transports from the Sargasso Sea to the feeding areas of North America, Europe and North Africa. Recent but debatable research suggests that eels may use Earth's magnetic field to navigate through the sea as both larvae and as adults.
Climate
Climate is influenced by surface water temperature and water flow and wind. Due to the marvelous ability of the ocean to store and release heat, the maritime climate is more moderate and has less extreme seasonal variations than the terrestrial climate. Precipitation can be estimated from coastal weather data and air temperature from water temperature.
Oceans are the main source of atmospheric moisture obtained by evaporation. The climate zone varies with latitude; the hottest zone stretching north of the Atlantic at the equator. The coldest zones are in high latitudes, with the coldest areas corresponding to areas covered by sea ice. Ocean currents affect the climate by transporting warm and cold water to other areas. The wind that is cooled or warmed when blowing over the current affects adjacent land areas.
The Gulf Stream and the northern extension to Europe, the North Atlantic Drift is expected to have an effect on the climate. For example, the Gulf Stream helps moderate winter temperatures along the southeast coast of North America, keeping it warm in the winter along the coast rather than in the countryside. The Gulf Stream also maintains the extreme temperatures of what is happening in the Florida peninsula. At higher latitudes, the North Atlantic Drift, warms the atmosphere above the ocean, keeping the British Isles and northwestern Europe light and cloudy, and not very cold in winter like other locations in the same high latitudes. Cold streams contribute to the thick fog off the coast of eastern Canada (Grand Banks of Newfoundland area) and the northwest coast of Africa. In general, winds carry moisture and air above the ground.
Natural hazards
The iceberg is common from early February to late July on a cruise line near the Grand Banks of Newfoundland. The ice season is longer in the polar regions, but there is little shipping in these areas.
Hurricane is dangerous in the western part of the North Atlantic during summer and autumn. Due to consistently strong wind shear and the weak Intertropical Convergence Zone, they are practically unknown in the South Atlantic.
Plate tectonics
Middle Atlantic
The outbreak of Pangea began in the Middle Atlantic, between North America and Northwest Africa, where cracks were built during the Triassic and Early Jurassic End. This period also sees the first phase of the Atlas Mountains lift. The exact time is still controversial with estimates ranging from 200 to 170 Ma.
The opening of the Atlantic Ocean coincided with the outbreak of Pangea supercontinent, both triggered by the eruption of Central Atlantic Magmatic Province (CAMP), one of the largest and most diverse provinces in Earth's history. with the Triassic-Jurassic extinction event, one of Earth's great extinction events. Dams, frames, and lava flows from the CAMP eruption in 200 Ma have been found in West Africa, eastern North America, and northern South America. The extent of volcanism has been estimated 4.5 ÃÆ' - 10 6 km 2 (1,7 ÃÆ' - 10 6 sqÃ, mi) where 2.5 ÃÆ' - 10 6 Ã, km 2 (9,7 ÃÆ'â € " 10 5 sq sq) includes what is now northern and central Brazil.
The Establishment of Central America's Isthmus closes the American Seaway at the end of the Pliocene 2.8 Ma. The formation of the precarious soil resulted in the migration and extinction of many animals that live on land, known as the Great American Configuration Intersection, but the ocean's cover resulted in the "Great American Schism" because it affects ocean currents, salinity, and temperatures at sea. both Atlantic and Pacific. Marine organisms on both sides of isthmus become isolated and either diverged or extinct.
North America
Geologically the North Atlantic is an area bounded to the south by two conjugate boundaries, Newfoundland and Iberia, and to the north by the Arctic Eurasian Basin. The North Atlantic clearance closely follows the borders of its predecessor, the Ocean of Iapetus, and spread from the Middle Atlantic in six stages: Iberia-Newfoundland, Hedgehog-North America, Eurasia-Greenland, Eurasia-North America. Active and inactive spreading systems in this area are characterized by interactions with Icelandic hotspots.
South Atlantic
West Gondwana (South America and Africa) broke up in Early Cretace to form the South Atlantic. The clear distance between the shorelines of the two continents is listed on the first map which includes the South Atlantic and is also the subject of the reconstruction of the first computer-aided tectonic plates in 1965. However, this remarkable match has proved problematic and then reconstruction has introduced various zones deformation along the coastline to accommodate the splits that spread northward. Rift and continental deformation have also been introduced to divide the two continental plates into sub-plates.
Geologically the South Atlantic can be divided into four segments: Equatorial segment, from 10 Â ° N to 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 Agulhas-Falkland Fracture Zone (AFFZ); and the Falkland segment, south of AFFZ.
In the south segment of the Early Cretaceous intensive plural (133-130 Ma) of the ParanÃÆ'¡-Etendeka Large Igneous Province produced by Tristan hotspot yields an estimated volume of 1.5 ÃÆ' - 10 6 up to 2.0 ÃÆ' - 10 6 Ã, km 3 (3,6 ÃÆ' - 10 5 up to 4.8 ÃÆ' - 10 5 Ã, cuÃ, mi). It covers an area of ​​1.2 ÃÆ' - 10 6 up to 1.6 ÃÆ' - 10 6 Ã, km 2 (4.6 ÃÆ' - 10 5 to 6.2 ÃÆ' - 10 5 sq sq mi) in Brazil, Paraguay, and Uruguay and 0.8 ÃÆ' - 10 5 km 2 (3,1 Ã mi - 10 4 sq sq) in Africa. Dyke's rivals in Brazil, Angola, eastern Paraguay, and Namibia, however, show that LIP originally covered a much larger area and also showed a failing split in all these areas. The associated offshore basal currents reach as far south as the Falkland Islands and South Africa. Traces of magmatism in both offshore and inland 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.
In rifting the Falkland segment begins with a dextral movement between Patagonia and Colorado sub-plate between the Early Jurassic (190M) and Early Cretaceous (126.7 Ma). Approximately 150 m of sea floor spread spread northward to the southern segment. No more than 130 Ma rifting has reached Walvis Ridge-Rio Grande Rise.
In the middle of the segment rifting began to break Africa in two by opening the Benue Trench around 118 Ma. Rifting in the central segment, however, coincides with the Cretaceous Normal Superchron (also known as the Cretaceous quiet period), the 40 Ma period without a magnetic reversal, which makes it difficult to date the ocean spread in this segment.
Equatorial segment is the last phase of the solution, but, since it is located on the Equator, magnetic anomalies can not be used for dating. Various approximate sea floor deployment dates spread across this segment to the period of 120-96 Ma. This final stage, however, coincides with or leads to the end of continental extension in Africa.
Approximately 50 Ma The opening of the Drake Strait results from changes in the movement and degree of separation of the South American and Antarctic plates. The first small ocean basin is opened and a shallow gate appears during the Middle Eocene. 34-30 Ma a deeper ocean developed, followed by Eocene-Oligocene climatic damage and Antarctic ice sheet growth.
Atlantic Closure
The embryonic subduction limit potentially develops in western Gibraltar. The Gibraltar Arc in the western Mediterranean migrates west to the Middle Atlantic where it joins the convergent African and Eurasian plates. Together these three tectonic forces gradually evolved into a new subduction system in the eastern Atlantic Basin. Meanwhile, the Scotia Arc and Caribbean Plate in the West Atlantic Basin is a possible eastern subduction system, along with the Gibraltar system, representing the beginning of the closure of the Atlantic Ocean and the final stage of the Wilson Atlantic cycle.
History
Origin of human
Humans evolved in Africa; first by deviating from another ape around 7 Ma; then develop stone tools around 2.6 Ma; to finally evolve as a modern man around 100 kya. The earliest evidence for the complex behavior associated with modernity of behavior has been found in the Greater Cape Floristic Region (GCFR) along the coast of South Africa. During the latest glacial phase, the Agulhas plains are now submerged above sea level, extending to the South African coast further south for hundreds of kilometers. The small population of modern humans - perhaps less than a thousand individual reproductions - survived the glacial maxima by exploring the high diversity offered by this Palaeo-Agulhas plateau. The GCFR is limited to the north by the Cape Fold Belt and its limited space to the south results in the development of social networks where complex Stone Age technologies emerge. Therefore, human history begins on the coast of South Africa where the Atlantic Benguela Upwelling and Indian Ocean Agulhas meet today to produce an intertidal zone where shellfish, feather seals, fish and seabirds provide the necessary protein source. The African origins of this modern behavior are evidenced by the 70,000 year carving of the Blombos Cave, South Africa.
Old World
Mitochondrial DNA studies (mtDNA) show that 80-60,000 years ago a major demographic expansion in Africa, derived from a single, small population, coincided with the emergence of complexity of behavior and 5-4 MIS rapid environmental changes. This group of people not only spread throughout Africa, but also began spreading out of Africa to Asia, Europe and Australasia about 65,000 years ago and quickly replaced the early humans in the region. During the Last Glacial Maximum (LGM) 20,000 years ago humans had to abandon their early settlement along the North Atlantic coast of Europe and retreated to the Mediterranean. After rapid climate change at the end of LGM, the area is again inhabited by the Magdalenian culture. Other hunter-gatherers follow waves disturbed by large-scale dangers such as Laacher See volcanic eruptions, Doggerland puddles (now the North Sea), and the formation of the Baltic Sea. The European coast of the North Atlantic is permanently inhabited about 9-8.5 thousand years ago.
This human spreading leaves traces abundant along the Atlantic Ocean coast. Highly coated layered shell monkeys found in Ysterfontein on the west coast of South Africa are associated with the Middle Stone Age (MSA). MSA populations are small and scattered and their reproductive and exploitation levels are less strong than the next generation. While their middens resemble the 12-11Ã, ka-old Late Stone Age (LSA) middens found in every inhabited continent, the 50-45-year-old Enkapune Ya Muto in Kenya may represent the oldest traces of the first modern humans to spread out of Africa..
The same development can be seen in Europe. In La Riera Cave (23-13Ã, ka) in Asturias, Spain, only about 26,600 molluscs are stored above 10Ã, ka. In contrast, the bowls of 8-7Ã, the elderly in Portugal, Denmark, and Brazil produce thousands of tons of debris and artifacts. The ErtebÃÆ'¸lle middens in Denmark, for example, collect 2,000 m 3 (71,000 cuÃ,ft) of shell deposits representing about 50 million mollusks for just a thousand years. This intensification in the exploitation of marine resources has been described as accompanied by new technologies - such as boats, spears, and fish hooks - as many of the caves found in the Mediterranean and on the Atlantic coast of Europe have increased the number of sea shells at their top levels and the number is reduced in parts down them. The earliest exploitation, however, occurred on shelves that are now submerged, and most of the settlements that are now dug up are located several kilometers from these shelves. The quantity of the reduced shell at the lower level may represent some of the shells exported to the land.
New World
During LGM, Laurentide's Ice Sheet covers most of northern North America while Beringia connects Siberia to Alaska. In 1973, US geoscientist Paul S. Martin proposed an American "blitzkrieg" colonization with Clovis hunters migrating to North America about 13,000 years ago in one wave through ice-free corridors in the ice and "spreading explosively to the south, briefly. reaching a large enough density to kill many of their prey. "Others then propose a" three wave "migration over the Tanah Bering Bridge. These hypotheses remain a long-held view of American settlements, a view challenged by recent archaeological discoveries: the oldest archaeological site in America has been found in South America; sites in northeastern Siberia reported no human presence there during LGM; and most Clovis artifacts have been found in eastern North America along the Atlantic coast. In addition, colonization models based on mtDNA, yDNA, and atDNA data do not support the "blitzkrieg" or "three wave" hypotheses, but also provide unclear results. Contradictory data from archeology and genetics are likely to produce future hypotheses that will eventually confirm each other. The proposed route across the Pacific to South America can account for the early findings of South America and other hypotheses proposing the northern route, through the Canadian Arctic and along the Atlantic coast of North America. Early settlements throughout the Atlantic have been suggested by alternative theories, ranging from purely hypothetical to the most disputed, including the Solutrean hypothesis and some Pre-Columbian trans-oceanic contact theory.
Norse settlements in the Faroe Islands and Iceland began in the 9th and 10th centuries. A settlement in Greenland was established before 1000 CE, but contact with it was lost in 1409 and was eventually abandoned during the early Small Ice Age. This setback is caused by various factors: unsustainable economies lead to erosion and deforestation, while conflicts with local Inuit lead to failure to adapt their Arctic technology; Colder climates lead to starvation; and the colony was economically marginalized when the Great Plague and the Barbary pirates harvested its victims in Iceland in the 15th century. Iceland initially settled 865-930 CE after a warm period when winter temperatures ranged around 2 Â ° C (36 Â ° F) which made farming profitable at high latitudes. However, this did not last long, and the temperature dropped rapidly; at summer CE temperature 1080 has reached a maximum of 5 Ã, Â ° C (41Ã, Â ° F). The LandnÃÆ'¡mabÃÆ'³k ( Book of Settlement ) notes the famine during the first century of settlement - "people eat foxes and crows" and "parents and helpless are killed and thrown over cliff "Ã, - and in the early 1200s, straw should be left for short-term crops such as barley.
The Atlantic world
Christopher Columbus discovered America in 1492 under the banner of Spain. Six years later Vasco da Gama reached India under the Portuguese flag, navigating southward around the Cape of Good Hope, thereby proving that the Atlantic Ocean and the Indies were connected. In 1500, on his way to India after Vasco da Gama, Pedro Alvares Cabral reached Brazil, which was taken by the current of Pilin the South Atlantic. After this exploration, Spain and Portugal quickly conquered and colonized large areas of the New World and forced the Native Americans into slaves to explore the large amounts of silver and gold they found. Spain and Portugal monopolized this trade to prevent other European countries from leaving, but conflicting interests continued to cause a series of Spanish-Portuguese wars. A peace agreement mediated by the Pope divided the conquered territories into Spanish and Portuguese sectors while alienating other colonial powers. Britain, France and the Republic of the Netherlands enviously watched Spanish and Portuguese wealth grow and ally with pirates such as Henry Mainwaring and Alexandre Exquemelin. They can explore convoys that leave America because of the prevailing winds and currents that make heavy metal transportation slow and predictable.
In the depression of American colonies, disease, and slavery are rapidly reducing the indigenous population of America to the extent that Atlantic slave trade must be introduced to replace them - trade into the norm and an integral part of colonization. Between the 15th and 1888th centuries, when Brazil became the last part of America to end the slave trade, it was estimated that ten million Africans were exported as slaves, most of them dedicated to agricultural labor. Slave trade was officially abolished in the United Kingdom and the United States in 1808, and slavery itself was abolished in the United Kingdom in 1838 and in the United States in 1865 after the Civil War.
From Columbus to the Trans-Atlantic Trade Industry Revolution, including colonialism and slavery, became very important to Western Europe. For European countries with direct access to the Atlantic (including England, France, the Netherlands, Portugal and Spain) 1500-1800 is a period of sustained growth where these countries grow richer than in Eastern Europe and Asia. Colonialism developed as part of the Trans-Atlantic trade, but this trade also strengthened the position of the merchant group at the expense of the king. Growth is faster in non-absolutist countries, such as Britain and the Netherlands, and more limited in absolute monarchies, such as Portugal, Spain, and France, where profits mostly or exclusively benefit the monarchy and its allies.
Trans-Atlantic trade has also resulted in increased urbanization: in the European countries facing Atlantic urbanization grew from 8% in 1300, 10.1% in 1500, to 24.5% in 1850; in other European countries from 10% at 1300, 11.4% in 1500, to 17% in 1850. Similarly, GDP doubled in Atlantic countries but only rose 30% across Europe. By the end of the 17th century the trans-Atlantic trade volume had surpassed the Mediterranean trade.
Economy
The Atlantic has made a significant contribution to the development and economy of the surrounding countries. In addition to major transatlantic transport and communications routes, the Atlantic offers abundant oil deposits in continental shelf sedimentary rocks.
The Atlantic Ocean is a port of oil 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 underwater on the seafloor, but the deposits are also encased in rocks that must be mined. Currently, there is no effective way to mine or extract gold from the ocean for profit.
Various international agreements seek to reduce pollution caused by environmental threats such as oil spills, marine waste, and burning of toxic wastes at sea.
fishery
Atlantic shelves become one of the richest fish resources in the world. The most productive areas include Grand Bank of Newfoundland, Shelf Scotian, Georges Bank on Cape Cod, Bahama Banks, waters around Iceland, the Irish Sea, Bay of Fundy, Dogger Bank in the North Sea, and Falkland Bank. Fisheries, however, experienced significant changes since the 1950s and global catchments can now be divided into three groups that only two are observed in the Atlantic: fisheries in the Middle East and South-West Atlantic oscillate around globally stable values, the rest of the Atlantic as a whole decreased following the historical peak. The third group, "the trend continues to increase since 1950", is only found in the Indian Ocean and the Western Pacific.
In the North Atlantic-Sea catchment area decreased between the mid-1970s and 1990s and reached 8.7 million tons in 2013. Blue lime series reached a peak of 2.4 million tons in 2004 but fell to 628,000 tons in 2013 The recovery plan for cod, sole, and plaice has reduced mortality in this species. The Arctic Cod reached its lowest level in the 1960s-1980s but is now recovering. Arctic saithe and haddock are considered fully fishing; Sand eels captured in excess like capelin that has now fully recovered. Limited data make the state of redfish fish and deepwater species difficult to assess but they are likely to remain vulnerable to overfishing. Stock of northern shrimp and Norwegian lobster in good condition. In the North-East Atlantic, 21% of shares are considered excessive.
In the North-West Atlantic landing has decreased from 4.2 million tons in the early 1970s to 1.9 million tons in 2013. During the 21st century some species have shown signs of weak recovery, including Greenland halibut, flounder yellow, halibut Atlantic, haddock, spiked dogfish, while other stocks do not show such signs, including cod, floating wizards, and redfish. The invertebrate stock, on the contrary, remains at the record level of abundance. 31% of the stocks were caught excessively in the North-west Atlantic.
In 1497 John Cabot became the first to explore the mainland of North America and one of his major discoveries was the abundant source of Atlantic cod in Newfoundland. Referred to as "Newfoundland Currency" this invention supplies humans with about 200 million tons of fish for five centuries. In the late 19th and early 20th centuries, new fisheries began to utilize haddock, mackerel, and lobster. From the 1950s to the 1970s, the introduction of European and Asian long-distance fleets in the region dramatically increased the fishing capacity and number of exploited species. It also expands the exploited area from near the shore to the open sea and to a very deep depth to include deep water species such as red fish, Greenland halibut, flounder mages, and grenadiers. Overfishing in the area was recognized in the early 1960s, but, as it happened in international waters, it took until the late 1970s before attempts to set up were made. In the early 1990s this eventually resulted in the collapse of the northwest Atlantic cod fishery. The populations of a number of deep-sea fish also collapse in the process, including American plaice, redfish, and Greenland halibut, along with flounder and grenadier.
In the Middle East Atlantic small pelagic fish constitute about 50% of landings with sardines reaching 0.6 to 1.0 million tons per year. The stock of pelagic fish is considered as whole fish or over-fish, with sardines in southern Cape Bojador as an exception. Nearly half of the stock is caught at levels that are not biologically sustainable. Total catch has fluctuated since the 1970s; reaching 3.9 million tons in 2013 or slightly lower than peak production in 2010.
In the western part of the western Atlantic the catch has declined since 2000 and reached 1.3 million tons in 2013. The most important species in the area, the Bay of menhaden, reached one million tons in the mid-1980s but only half a million tons in 2013 and now. considered fully fishing. Round Sardinella was an important species in the 1990s but is now considered overtaken. Overcrowded grouper and snapper and northern chocolate shrimp and oyster bowl America are considered fully fishing near overfishing. 44% of the shares are fishing at unsustainable levels.
In the Southeast Atlantic catchment area decreased from 3.3 million tons in the early 1970s to 1.3 million tons in 2013. Horse and hake mackerel are the most important species, together representing nearly half of the landings. Outside of South Africa and Namibia, deep and upstream waters of the Cape have recovered to a sustainable level since regulations introduced in 2006 and the southern African states of pilchard and anchovy have risen to fully fishing in 2013.
In the South-West Atlantic peaks were achieved in the mid-1980s and catches now fluctuate between 1.7 and 2.6 million tons. The most important species, the short squid of Argentina, which reaches half a million tons in 2013 or half the peak value, is considered entirely fishing for overfishing. Another important species is the Brazilian sardinella, with 100,000 tons production by 2013, now considered excessive. Half of the stock in this area is fishing at an unsustainable level: Whitehead's round herring has not yet reached full capture but Cunene horse mackerel is overcaptured. The sea snails of Perlemoen abalone are targeted by illegal fishermen and are still caught redundantly.
Environmental issues
Endangered marine species include manatees, seals, sea lions, turtles, and whales. The drifting of fish can kill dolphins, albatrosses, and other sea birds (petrel, auks), accelerate the decline of fish stocks and contribute to international disputes. Urban pollution comes from the eastern United States, southern Brazil, and eastern Argentina; oil pollution in the Caribbean Sea, Gulf of Mexico, Maracaibo Lake, Mediterranean Sea and North Sea; and industrial waste and municipal waste pollution in the Baltic Sea, the North Sea, and the Mediterranean Sea.
North Atlantic hurricane activity has increased over the last few decades due to rising sea surface temperature (SST) in tropical latitudes, a change that can be attributed to Natural Atlantic Multidecadal Oscillation (AMO) or anthropogenic climate change. The 2005 report shows that Atlantic Atlantic's inverted circulation (AMOC) slowed by 30% between 1957 and 2004. If AMO is responsible for the variability of SST, the AMOC will increase in strength, which does not happen. Furthermore, it is clear from the annual tropical cyclone statistical analysis that these changes do not show multidecadal cyclicality. Therefore, the changes in this SST must be caused by human activity.
The ocean mix layer plays an important role of heat storage over the seasonal and decadal time scales, while the deeper layers are affected for thousands of years and have a heat capacity about 50 times that of the mixed layers. This heat acquisition provides time delays for climate change but also results in ocean thermal expansions that contribute to sea level rise. Global warming of the 21st century will probably produce sea-level rise as thick as five times larger than it is today, while melting glaciers, including the Greenland ice sheet, is thought to be virtually unimportant during the 21st century, possibly resulting in a 3-6 m rise in sea level over one millennium.
On June 7, 2006, the Florida wildlife commission voted to take the manate from the list of endangered species of the country. Some environmentalists fear that this could erode the safety framework for popular marine creatures.
Marine pollution is a generic term for entry into oceans of potentially harmful chemicals or particles. The biggest perpetrators are rivers and with them a lot of agricultural chemical fertilizers as well as livestock and human waste. Excess oxygen-promoting chemicals cause hypoxia and the formation of dead zones.
Marine debris, also known as marine waste, represents man-made wastes floating in water bodies. Ocean fragments tend to accumulate in the center of the gear and coastline, often washing aground where is known as beach waste.
See also
- List of countries and territories adjacent to the Atlantic Ocean
- Seven Seas
- Gulf Stream Playback
- Shipwreck in the Atlantic Ocean
- Atlantic Storm
- Transatlantic crossing
References
Note
Source
Further reading
- Winchester, Simon (2010). Atlantic: The Great Ocean of a Million Stories . HarperCollins UK. ISBN: 978-0-00-734137-5.
External links
- Atlantic Ocean. Cartage.org.lb.
- "North American Atlantic Coast Map from Chesapeake Bay to Florida" from 1639 via World Digital Library
Source of the article : Wikipedia
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