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Atlantic Ocean

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Atlantic Ocean
Map of the Arctic Ocean
Extent of the Atlantic Ocean according to the 2002 IHO definition, excluding Arctic and Antarctic regions
Coordinates0°N 25°W / 0°N 25°W / 0; -25Coordinates: 0°N 25°W / 0°N 25°W / 0; -25[1]
Basin countriesList of bordering countries (not drainage basin), ports
Surface area106,460,000 km2 (41,100,000 sq mi)[2][3]
North Atlantic: 41,490,000 km2 (16,020,000 sq mi),
South Atlantic 40,270,000 km2 (15,550,000 sq mi)[4]
Average depth3,646 m (11,962 ft)[4]
Max. depthPuerto Rico Trench
8,376 m (27,480 ft)[5]
Water volume310,410,900 km3 (74,471,500 cu mi)[4]
Shore length1111,866 km (69,510 mi) including marginal seas[1]
IslandsList of islands
TrenchesPuerto Rico; South Sandwich; Romanche
Settlements
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 five oceans, with an area of about 106,460,000 km2 (41,100,000 sq mi).[2][3] It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe, and Asia from the "New World" of the Americas in the European perception of the World.

Through its separation from Africa, Europe, and Asia from the Americas, the Atlantic Ocean has played a central role in the development of human society, globalization, and the history of many nations. While the Norse were the first humans to cross the Atlantic, it was the 1492 expedition of Christopher Columbus which proved to be the most consequential. Columbus's expedition ushered in an age of exploration and colonization of the Americas by European powers, most notably Spain, France, and the United Kingdom. From the 16th to 19th centuries, the Atlantic Ocean was the center of both an eponymous slave trade and the Columbian exchange while occasionally hosting naval battles. Such naval battles, as well as growing trade from regional American powers like the United States and Brazil, both increased in degree during the 20th century, and while no major military conflicts took place in the Atlantic in the present 21st century, the ocean remains a core component of trade across the world.

The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Europe and Africa to the east, and North and South America to the west. As one component of the interconnected World Ocean, it is connected in the north to the Arctic Ocean, to the Pacific Ocean in the southwest, the Indian Ocean in the southeast, and the Southern Ocean in the south (other definitions describe the Atlantic as extending southward to Antarctica). The Atlantic Ocean is divided in two parts, by the Equatorial Counter Current, with the North(ern) Atlantic Ocean and the South(ern) Atlantic Ocean split at about 8°N.[6]

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Africa

Africa

Africa is the world's second-largest and second-most populous continent, after Asia in both aspects. At about 30.3 million km2 including adjacent islands, it covers 20% of Earth's land area and 6% of its total surface area. With 1.4 billion people as of 2021, it accounts for about 18% of the world's human population. Africa's population is the youngest amongst all the continents; the median age in 2012 was 19.7, when the worldwide median age was 30.4. Despite a wide range of natural resources, Africa is the least wealthy continent per capita and second-least wealthy by total wealth, behind Oceania. Scholars have attributed this to different factors including geography, climate, tribalism, colonialism, the Cold War, neocolonialism, lack of democracy, and corruption. Despite this low concentration of wealth, recent economic expansion and the large and young population make Africa an important economic market in the broader global context.

Asia

Asia

Asia is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometers, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which has long been home to the majority of the human population, was the site of many of the first civilizations. Its 4.7 billion people constitute roughly 60% of the world's population, having more people than all other continents combined.

Americas

Americas

The Americas are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World.

Earth

Earth

Earth is the third planet from the Sun and the only place known in the universe where life has originated and found habitability. While Earth may not contain the largest volumes of water in the Solar System, only Earth sustains liquid surface water, extending over 70.8% of the Earth with its ocean, making Earth an ocean world. Earth's polar regions currently retain most of all other water with large sheets of ice covering ocean and land, dwarfing Earth's groundwater, lakes, rivers and atmospheric water. Land, consisting of continents and islands, extends over 29.2% of the Earth and is widely covered by vegetation. Below Earth's surface material lies Earth's crust consisting of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's liquid outer core generates a magnetic field that shapes the magnetosphere of Earth, largely deflecting destructive solar winds and cosmic radiation.

Christopher Columbus

Christopher Columbus

Christopher Columbus was an Italian explorer and navigator from the Republic of Genoa who completed four voyages across the Atlantic Ocean sponsored by the Catholic Monarchs of Spain, opening the way for the widespread European exploration and European colonization of the Americas. His expeditions were the first known European contact with the Caribbean and Central and South America.

Age of Discovery

Age of Discovery

The Age of Discovery or the Age of Exploration, part of the early modern period and largely overlapping with the Age of Sail, was a period from approximately the 15th century to the 17th century in European history, during which seafaring Europeans explored, colonized, and conquered regions across the globe.

Atlantic slave trade

Atlantic slave trade

The Atlantic slave trade, transatlantic slave trade, or Euro-American slave trade involved the transportation by slave traders of enslaved African people, mainly to the Americas. The slave trade regularly used the triangular trade route and its Middle Passage, and existed from the 16th to the 19th centuries. The vast majority of those who were transported in the transatlantic slave trade were people from Central and West Africa that had been sold by other West Africans to Western European slave traders, while others had been captured directly by the slave traders in coastal raids; Europeans gathered and imprisoned the enslaved at forts on the African coast and then brought them to the Americas. Except for the Portuguese, European slave traders generally did not participate in the raids because life expectancy for Europeans in sub-Saharan Africa was less than one year during the period of the slave trade. The colonial South Atlantic and Caribbean economies were particularly dependent on labour for the production of sugarcane and other commodities. This was viewed as crucial by those Western European states which, in the late 17th and 18th centuries, were vying with one another to create overseas empires.

Columbian exchange

Columbian exchange

The Columbian exchange, also known as the Columbian interchange, was the widespread transfer of plants, animals, precious metals, commodities, culture, human populations, technology, diseases, and ideas between the New World in the Western Hemisphere, and the Old World (Afro-Eurasia) in the Eastern Hemisphere, in the late 15th and following centuries. It is named after the Italian explorer Christopher Columbus and is related to the European colonization and global trade following his 1492 voyage. Some of the exchanges were purposeful; some were accidental or unintended. Communicable diseases of Old World origin resulted in an 80 to 95 percent reduction in the number of Indigenous peoples of the Americas from the 15th century onwards, most severely in the Caribbean. The cultures of both hemispheres were significantly impacted by the migration of people from the Old World to the New. European colonists and African slaves replaced Indigenous populations across the Americas, to varying degrees. The number of Africans taken to the New World was far greater than the number of Europeans moving to the New World in the first three centuries after Columbus.

Brazil

Brazil

Brazil, officially the Federative Republic of Brazil, is the largest country in South America and in Latin America. At 8.5 million square kilometers (3,300,000 sq mi) and with over 217 million people, Brazil is the world's fifth-largest country by area and the seventh most populous. Its capital is Brasília, and its most populous city is São Paulo. The federation is composed of the union of the 26 states and the Federal District. It is the only country in the Americas to have Portuguese as an official language. It is one of the most multicultural and ethnically diverse nations, due to over a century of mass immigration from around the world, and the most populous Roman Catholic-majority country.

Arctic Ocean

Arctic Ocean

The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately 14,060,000 km2 (5,430,000 sq mi) and is known as the coldest of all the oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea. It has been also been described as an estuary of the Atlantic Ocean. It is also seen as the northernmost part of the all-encompassing World Ocean.

Antarctica

Antarctica

Antarctica is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest continent, being about 40% larger than Europe, and has an area of 14,200,000 km2 (5,500,000 sq mi). Most of Antarctica is covered by the Antarctic ice sheet, with an average thickness of 1.9 km (1.2 mi).

8th parallel north

8th parallel north

The 8th parallel north is a circle of latitude that is 8 degrees north of the Earth's equatorial plane. It crosses Africa, the Indian Ocean, South Asia, Southeast Asia, the Pacific Ocean, Central America, South America and the Atlantic Ocean.

Toponymy

The Aethiopian Ocean in a 1710 French map of Africa
The Aethiopian Ocean in a 1710 French map of Africa

The oldest known mentions of an "Atlantic" sea come from Stesichorus around mid-sixth century BC (Sch. A. R. 1. 211):[7] Atlantikôi pelágei (Greek: Ἀτλαντικῷ πελάγει; English: 'the Atlantic sea'; etym. 'Sea of Atlas') and in The Histories of Herodotus around 450 BC (Hdt. 1.202.4): Atlantis thalassa (Greek: Ἀτλαντὶς θάλασσα; English: 'Sea of Atlas' or 'the Atlantic 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.[9] In these uses, the name refers to Atlas, the Titan in Greek mythology, who supported the heavens and who later appeared as a frontispiece in Medieval maps and also lent his name to modern atlases.[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.[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.[10] The Greek word thalassa has been reused by scientists for the huge Panthalassa ocean that surrounded the supercontinent Pangaea hundreds of millions of years ago.

The term "Aethiopian Ocean", derived from Ancient Ethiopia, was applied to the Southern Atlantic as late as the mid-19th century.[12] During the Age of Discovery, the Atlantic was also known to English cartographers as the Great Western Ocean.[13]

The pond is a term often used by British and American speakers in reference to the Northern Atlantic Ocean, as a form of meiosis, or ironic understatement. It is used mostly when referring to events or circumstances "on this side of the pond" or "on the other side of the pond", rather than to discuss the ocean itself.[14] The term dates to 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.[15][16][17]

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Atlas (mythology)

Atlas (mythology)

In Greek mythology, Atlas is a Titan condemned to hold up the heavens or sky for eternity after the Titanomachy. Atlas also plays a role in the myths of two of the greatest Greek heroes: Heracles and Perseus. According to the ancient Greek poet Hesiod, Atlas stood at the ends of the earth in extreme west. Later, he became commonly identified with the Atlas Mountains in northwest Africa and was said to be the first King of Mauretania. Atlas was said to have been skilled in philosophy, mathematics, and astronomy. In antiquity, he was credited with inventing the first celestial sphere. In some texts, he is even credited with the invention of astronomy itself.

Histories (Herodotus)

Histories (Herodotus)

The Histories of Herodotus is considered the founding work of history in Western literature. Written around 430 BC in the Ionic dialect of classical Greek, The Histories serves as a record of the ancient traditions, politics, geography, and clashes of various cultures that were known in Greece, Western Asia and Northern Africa at that time. Although not a fully impartial record, it remains one of the West's most important sources regarding these affairs. Moreover, it established the genre and study of history in the Western world.

Herodotus

Herodotus

Herodotus was a Greek historian and geographer from the Greek city of Halicarnassus, part of the Persian Empire and a later citizen of Thurii in modern Calabria (Italy). He is known for having written the Histories – a detailed account of the Greco-Persian Wars. Herodotus was the first writer to perform systematic investigation of historical events. He is referred to as "The Father of History", a title conferred on him by the ancient Roman orator Cicero.

Greek mythology

Greek mythology

A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities of deities, heroes, and mythological creatures, and the origins and significance of the ancient Greeks' own cult and ritual practices. Modern scholars study the myths to shed light on the religious and political institutions of ancient Greece, and to better understand the nature of myth-making itself.

Ancient Greece

Ancient Greece

Ancient Greece was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity, that comprised a loose collection of culturally and linguistically related city-states and other territories. Most of these regions were officially unified only once, for 13 years, under Alexander the Great's empire from 336 to 323 BC. In Western history, the era of classical antiquity was immediately followed by the Early Middle Ages and the Byzantine period.

Iliad

Iliad

The Iliad is one of two major ancient Greek epic poems attributed to Homer. It is one of the oldest extant works of literature still widely read by modern audiences. As with the Odyssey, the poem is divided into 24 books and was written in dactylic hexameter. It contains 15,693 lines in its most widely accepted version. Set towards the end of the Trojan War, a ten-year siege of the city of Troy by a coalition of Mycenaean Greek states, the poem depicts significant events in the siege's final weeks. In particular, it depicts a fierce quarrel between King Agamemnon and a celebrated warrior, Achilles. It is a central part of the Epic Cycle. The Iliad is often regarded as the first substantial piece of European literature.

Odyssey

Odyssey

The Odyssey is one of two major ancient Greek epic poems attributed to Homer. It is one of the oldest extant works of literature still widely read by modern audiences. As with the Iliad, the poem is divided into 24 books. It follows the Greek hero Odysseus, king of Ithaca, and his journey home after the Trojan War. After the war, which lasted ten years, his journey lasted for ten additional years, during which time he encountered many perils and all his crewmates were killed. In his absence, Odysseus was assumed dead, and his wife Penelope and son Telemachus had to contend with a group of unruly suitors who were competing for Penelope's hand in marriage.

Oceanus

Oceanus

In Greek mythology, Oceanus was a Titan son of Uranus and Gaia, the husband of his sister the Titan Tethys, and the father of the river gods and the Oceanids, as well as being the great river which encircled the entire world.

Atlas Mountains

Atlas Mountains

The Atlas Mountains are a mountain range in the Maghreb in North Africa. It separates the Sahara Desert from the Mediterranean Sea and the Atlantic Ocean; the name "Atlantic" is derived from the mountain range. It stretches around 2,500 km (1,600 mi) through Morocco, Algeria and Tunisia. The range's highest peak is Toubkal, which is in central Morocco, with an elevation of 4,167 metres (13,671 ft). The Atlas mountains are primarily inhabited by Berber populations.

Panthalassa

Panthalassa

Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean, was the superocean that surrounded the supercontinent Pangaea, the latest in a series of supercontinents in the history of Earth. During the Paleozoic–Mesozoic transition c. 250 Ma it occupied almost 70% of Earth's surface. Its ocean floor has completely disappeared because of the continuous subduction along the continental margins on its circumference. Panthalassa is also referred to as the Paleo-Pacific or Proto-Pacific because the Pacific Ocean is a direct continuation of Panthalassa.

Pangaea

Pangaea

Pangaea or Pangea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million years ago, and began to break apart about 200 million years ago, at the end of the Triassic and beginning of the Jurassic. In contrast to the present Earth and its distribution of continental mass, Pangaea was centred on the equator and surrounded by the superocean Panthalassa and the Paleo-Tethys and subsequent Tethys Oceans. Pangaea is the most recent supercontinent to have existed and the first to be reconstructed by geologists.

Aethiopia

Aethiopia

Ancient Aethiopia, first appears as a geographical term in classical documents in reference to the upper Nile region of Sudan, as well as certain areas south of the Sahara. Its earliest mention is in the works of Homer: twice in the Iliad, and three times in the Odyssey. The Greek historian Herodotus "specifically" uses the appellation to refer to such parts of sub-Saharan Africa as were then known within the inhabitable world.

Extent and data

The International Hydrographic Organization (IHO) defined the limits of the oceans and seas in 1953,[18] 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 vary.

The Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea and Barents Sea. To 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.[18]

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.[1] 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.[1][19]

Including its marginal seas, the Atlantic covers an area of 106,460,000 km2 (41,100,000 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% of the total volume of the earth's oceans. Excluding its marginal seas, the Atlantic covers 81,760,000 km2 (31,570,000 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%).[4] The average depth is 3,646 m (11,962 ft) and the maximum depth, the Milwaukee Deep in the Puerto Rico Trench, is 8,376 m (27,480 ft).[20][21]

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International Hydrographic Organization

International Hydrographic Organization

The International Hydrographic Organization (IHO) is an intergovernmental organisation representing hydrography. As of May 2022, the IHO comprised 98 Member States.

Denmark Strait

Denmark Strait

The Denmark Strait or Greenland Strait is an oceanic strait between Greenland to its northwest and Iceland to its southeast. The Norwegian island of Jan Mayen lies northeast of the strait.

Greenland Sea

Greenland Sea

The Greenland Sea is a body of water that borders Greenland to the west, the Svalbard archipelago to the east, Fram Strait and the Arctic Ocean to the north, and the Norwegian Sea and Iceland to the south. The Greenland Sea is often defined as part of the Arctic Ocean, sometimes as part of the Atlantic Ocean. However, definitions of the Arctic Ocean and its seas tend to be imprecise or arbitrary. In general usage the term "Arctic Ocean" would exclude the Greenland Sea. In oceanographic studies the Greenland Sea is considered part of the Nordic Seas, along with the Norwegian Sea. The Nordic Seas are the main connection between the Arctic and Atlantic oceans and, as such, could be of great significance in a possible shutdown of thermohaline circulation. In oceanography the Arctic Ocean and Nordic Seas are often referred to collectively as the "Arctic Mediterranean Sea", a marginal sea of the Atlantic.

Barents Sea

Barents Sea

The Barents Sea is a marginal sea of the Arctic Ocean, located off the northern coasts of Norway and Russia and divided between Norwegian and Russian territorial waters. It was known among Russians in the Middle Ages as the Murman Sea ; the current name of the sea is after the historical Dutch navigator Willem Barentsz.

Mediterranean Sea

Mediterranean Sea

The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Southern Europe and Anatolia, on the south by North Africa, and on the east by the Levant in Western Asia. The Mediterranean has played a central role in the history of Western civilization. Geological evidence indicates that around 5.9 million years ago the Mediterranean was cut off from the Atlantic and was partly or completely desiccated over a period of some 600,000 years during the Messinian salinity crisis before being refilled by the Zanclean flood about 5.3 million years ago.

Black Sea

Black Sea

The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Romania, Russia, Turkey, and Ukraine. The Black Sea is supplied by major rivers, principally the Danube, Dnieper, and Don. Consequently, while six countries have a coastline on the sea, its drainage basin includes parts of 24 countries in Europe.

20th meridian east

20th meridian east

The meridian 20° east of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Europe, Africa, the Atlantic and Indian oceans, the Southern Ocean, and Antarctica to the South Pole.

Cape Agulhas

Cape Agulhas

Cape Agulhas is a rocky headland in Western Cape, South Africa. It is the geographic southern tip of Africa and the beginning of the dividing line between the Atlantic and Indian Oceans according to the International Hydrographic Organization. It is approximately half a degree of latitude, or 55 kilometres (34 mi), further south than the Cape of Good Hope.

Antarctica

Antarctica

Antarctica is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest continent, being about 40% larger than Europe, and has an area of 14,200,000 km2 (5,500,000 sq mi). Most of Antarctica is covered by the Antarctic ice sheet, with an average thickness of 1.9 km (1.2 mi).

60th parallel south

60th parallel south

The 60th parallel south is a circle of latitude that is 60 degrees south of Earth's equatorial plane. No land lies on the parallel—it crosses nothing but ocean. The closest land is a group of rocks north of Coronation Island of the South Orkney Islands, which are about 54 km south of the parallel, and Thule Island and Cook Island of the South Sandwich Islands, which both are about 57 km north of the parallel.

Baltic Sea

Baltic Sea

The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain.

Caribbean Sea

Caribbean Sea

The Caribbean Sea is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles starting with Cuba, to the east by the Lesser Antilles, and to the south by the northern coast of South America. The Gulf of Mexico lies to the northwest.

Biggest seas in Atlantic Ocean

Top large seas:[22][23][24]

  1. Sargasso Sea - 3.5 million km2
  2. Caribbean Sea - 2.754 million km2
  3. Mediterranean Sea - 2.510 million km2
  4. Gulf of Guinea - 2.35 million km2
  5. Gulf of Mexico - 1.550 million km2
  6. Norwegian Sea - 1.383 million km2
  7. Hudson Bay - 1.23 million km2
  8. Greenland Sea - 1.205 million km2
  9. Argentine Sea - 1 million km2
  10. Labrador Sea - 841,000 km2
  11. Irminger Sea - 780,000 km2
  12. Baffin Bay - 689,000 km2
  13. North Sea - 575,000 km2
  14. Black Sea - 436,000 km2
  15. Baltic Sea - 377,000 km2
  16. Libyan Sea - 350,000 km2
  17. Levantine Sea - 320,000 km2
  18. Celtic Sea - 300,000 km2
  19. Tyrrhenian Sea - 275,000 km2
  20. Gulf of Saint Lawrence - 226,000 km2
  21. Bay of Biscay - 223,000 km2
  22. Aegean Sea - 214,000 km2
  23. Ionian Sea - 169,000 km2
  24. Balearic Sea - 150,000 km2
  25. Adriatic Sea - 138,000 km2
  26. Gulf of Bothnia - 116,300 km2
  27. Sea of Crete - 95,000 km2
  28. Gulf of Maine - 93,000 km2
  29. Ligurian Sea - 80,000 km2
  30. English Channel - 75,000 km2
  31. James Bay - 68,300 km2
  32. Bothnian Sea - 66,000 km2
  33. Gulf of Sidra - 57,000 km2
  34. Sea of the Hebrides - 47,000 km2
  35. Irish Sea - 46,000 km2
  36. Sea of Azov - 39,000 km2
  37. Bothnian Bay - 36,800 km2
  38. Gulf of Venezuela - 17,840 km2
  39. Bay of Campeche - 16,000 km2
  40. Gulf of Lion - 15,000 km2
  41. Sea of Marmara - 11,350 km2
  42. Wadden Sea - 10,000 km2
  43. Archipelago Sea - 8,300 km2

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Caribbean Sea

Caribbean Sea

The Caribbean Sea is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles starting with Cuba, to the east by the Lesser Antilles, and to the south by the northern coast of South America. The Gulf of Mexico lies to the northwest.

Gulf of Guinea

Gulf of Guinea

The Gulf of Guinea is the northeasternmost part of the tropical Atlantic Ocean from Cape Lopez in Gabon, north and west to Cape Palmas in Liberia. The intersection of the Equator and Prime Meridian is in the gulf.

Gulf of Mexico

Gulf of Mexico

The Gulf of Mexico is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States; on the southwest and south by the Mexican states of Tamaulipas, Veracruz, Tabasco, Campeche, Yucatan, and Quintana Roo; and on the southeast by Cuba. The Southern U.S. states of Texas, Louisiana, Mississippi, Alabama, and Florida, which border the Gulf on the north, are often referred to as the "Third Coast" of the United States.

Hudson Bay

Hudson Bay

Hudson Bay, sometimes called Hudson's Bay, is a large body of saltwater in northeastern Canada with a surface area of 1,230,000 km2 (470,000 sq mi). It is located north of Ontario, west of Quebec, northeast of Manitoba and southeast of Nunavut, but politically entirely part of Nunavut. It is an inland marginal sea of the Arctic Ocean. It drains a very large area, about 3,861,400 km2 (1,490,900 sq mi), that includes parts of southeastern Nunavut, Alberta, Saskatchewan, Ontario, Quebec, all of Manitoba, and parts of the U.S. states of North Dakota, South Dakota, Minnesota, and Montana. Hudson Bay's southern arm is called James Bay.

Greenland Sea

Greenland Sea

The Greenland Sea is a body of water that borders Greenland to the west, the Svalbard archipelago to the east, Fram Strait and the Arctic Ocean to the north, and the Norwegian Sea and Iceland to the south. The Greenland Sea is often defined as part of the Arctic Ocean, sometimes as part of the Atlantic Ocean. However, definitions of the Arctic Ocean and its seas tend to be imprecise or arbitrary. In general usage the term "Arctic Ocean" would exclude the Greenland Sea. In oceanographic studies the Greenland Sea is considered part of the Nordic Seas, along with the Norwegian Sea. The Nordic Seas are the main connection between the Arctic and Atlantic oceans and, as such, could be of great significance in a possible shutdown of thermohaline circulation. In oceanography the Arctic Ocean and Nordic Seas are often referred to collectively as the "Arctic Mediterranean Sea", a marginal sea of the Atlantic.

Argentine Sea

Argentine Sea

The Argentine Sea is a marginal sea of the Atlantic Ocean adjacent to the southern tip of South America. It ranges from the mouth of the estuary of the Río de la Plata in the north to the Isla de los Estados in the south, and from the Argentine coast to the 200 meters isobath. Its width varies between 210 km in front of Mar del Plata and 850 km at the latitude of the Falkland Islands. The coastline extends for 4,725 km. To the east of the Argentine Sea extends much deeper and more extensive Argentine Basin.

Labrador Sea

Labrador Sea

The Labrador Sea is an arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland. The sea is flanked by continental shelves to the southwest, northwest, and northeast. It connects to the north with Baffin Bay through the Davis Strait. It is a marginal sea of the Atlantic.

Irminger Sea

Irminger Sea

The Irminger Sea is a marginal sea of the North Atlantic Ocean. It is bordered to the west by southern Greenland, to the north by Iceland and the Denmark Strait, to the east by the Reykjanes Ridge, and to the south by open waters of the North Atlantic.

Baffin Bay

Baffin Bay

Baffin Bay, located between Baffin Island and the west coast of Greenland, is defined by the International Hydrographic Organization as a marginal sea of the Arctic Ocean. It is sometimes considered a sea of the North Atlantic Ocean. It is connected to the Atlantic via Davis Strait and the Labrador Sea. The narrower Nares Strait connects Baffin Bay with the Arctic Ocean. The bay is not navigable most of the year because of the ice cover and high density of floating ice and icebergs in the open areas. However, a polynya of about 80,000 km2 (31,000 sq mi), known as the North Water, opens in summer on the north near Smith Sound. Most of the aquatic life of the bay is concentrated near that region.

Black Sea

Black Sea

The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Romania, Russia, Turkey, and Ukraine. The Black Sea is supplied by major rivers, principally the Danube, Dnieper, and Don. Consequently, while six countries have a coastline on the sea, its drainage basin includes parts of 24 countries in Europe.

Baltic Sea

Baltic Sea

The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain.

Celtic Sea

Celtic Sea

The Celtic Sea is the area of the Atlantic Ocean off the southern coast of Ireland bounded to the east by Saint George's Channel; other limits include the Bristol Channel, the English Channel, and the Bay of Biscay, as well as adjacent portions of Wales, Cornwall, and Brittany. The southern and western boundaries are delimited by the continental shelf, which drops away sharply. The Isles of Scilly are an archipelago of small islands in the sea.

Bathymetry

False color map of ocean depth in the Atlantic basin
False color 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 54°S.[25] Expeditions to explore the bathymertry of the Atlantic include the Challenger expedition and the German Meteor expedition; presently, Columbia University's Lamont–Doherty Earth Observatory and the United States Navy Hydrographic Office conduct research on the ocean.[6]

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 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. 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.[26]

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.[27] 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.[28]

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.[29] 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.[30]

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 [3,500 m; 11,400 ft] below the surface traverses the basins of the North and South Atlantic in a meridianal direction from Cape Farewell, probably its far south at least as Gough Island, following roughly the outlines of the coasts of the Old and the New Worlds.[31]

The remainder of the ridge was discovered in the 1920s by the German Meteor expedition using echo-sounding equipment.[32] The exploration of the MAR in the 1950s led to the general acceptance of seafloor spreading and plate tectonics.[25]

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.[25]

Ocean floor

Continental shelves in the Atlantic are wide off Newfoundland, southernmost 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 (8,376 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. 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.[26]

In 1922, a historic moment in cartography and oceanography occurred. The USS Stewart used a Navy Sonic Depth Finder to draw a continuous map across the bed of the Atlantic. This involved little guesswork because the idea of sonar is straightforward with pulses being sent from the vessel, which bounce off the ocean floor, then return to the vessel.[33] 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).[26]

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.

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False color

False color

False color refers to a group of color rendering methods used to display images in color which were recorded in the visible or non-visible parts of the electromagnetic spectrum. A false-color image is an image that depicts an object in colors that differ from those a photograph would show. In this image, colors have been assigned to three different wavelengths that our eyes cannot normally see.

Bathymetry

Bathymetry

Bathymetry is the study of underwater depth of ocean floors, lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water depth measurements are from Ancient Egypt over 3000 years ago. Bathymetric charts, are typically produced to support safety of surface or sub-surface navigation, and usually show seafloor relief or terrain as contour lines and selected depths (soundings), and typically also provide surface navigational information. Bathymetric maps may also use a Digital Terrain Model and artificial illumination techniques to illustrate the depths being portrayed. The global bathymetry is sometimes combined with topography data to yield a global relief model. Paleobathymetry is the study of past underwater depths.

Mid-Atlantic Ridge

Mid-Atlantic Ridge

The Mid-Atlantic Ridge is a mid-ocean ridge located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North American from the Eurasian Plate and the African Plate, north and south of the Azores Triple Junction. In the South Atlantic, it separates the African and South American plates. The ridge extends from a junction with the Gakkel Ridge northeast of Greenland southward to the Bouvet Triple Junction in the South Atlantic. Although the Mid-Atlantic Ridge is mostly an underwater feature, portions of it have enough elevation to extend above sea level, for example in Iceland. The ridge has an average spreading rate of about 2.5 centimetres (1 in) per year.

Bouvet Island

Bouvet Island

Bouvet Island is an island and dependency of Norway, and declared an uninhabited protected nature reserve. It is a subantarctic volcanic island, situated in the South Atlantic Ocean at the southern end of the Mid-Atlantic Ridge, making it the world's most remote island. It is not part of the southern region covered by the Antarctic Treaty System.

54th parallel south

54th parallel south

The 54th parallel south is a circle of latitude that is 54 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, the Indian Ocean, the Pacific Ocean and South America.

Challenger expedition

Challenger expedition

The Challenger expedition of 1872–1876 was a scientific programme that made many discoveries to lay the foundation of oceanography. The expedition was named after the naval vessel that undertook the trip, HMS Challenger.

German Meteor expedition

German Meteor expedition

The German Meteor expedition was an oceanographic expedition that explored the South Atlantic ocean from the equatorial region to Antarctica in 1925–1927. Depth soundings, water temperature studies, water samples, studies of marine life and atmospheric observations were conducted.

Columbia University

Columbia University

Columbia University is a private Ivy League research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhattan, it is the oldest institution of higher education in New York, the fifth-oldest in the United States, and one of nine colonial colleges founded prior to the Declaration of Independence.

Lamont–Doherty Earth Observatory

Lamont–Doherty Earth Observatory

The Lamont–Doherty Earth Observatory (LDEO) is the scientific research center of the Columbia Climate School, and a unit of The Earth Institute at Columbia University. It focuses on climate and earth sciences and is located on a 189-acre campus in Palisades, New York, 18 miles (29 km) north of Manhattan on the Hudson River.

53rd parallel north

53rd parallel north

The 53rd parallel north is a circle of latitude that is 53 degrees north of the Earth's equatorial plane. It crosses Europe, Asia, the Pacific Ocean, North America, and the Atlantic Ocean.

Divergent boundary

Divergent boundary

In plate tectonics, a divergent boundary or divergent plate boundary is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent boundaries within continents initially produce rifts, which eventually become rift valleys. Most active divergent plate boundaries occur between oceanic plates and exist as mid-oceanic ridges.

Eurasian Plate

Eurasian Plate

The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia, with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and the area east of the Chersky Range in eastern Siberia. It also includes oceanic crust extending westward to the Mid-Atlantic Ridge and northward to the Gakkel Ridge.

Water characteristics

As the Gulf Stream meanders across the North Atlantic from the North American east coast to Western Europe its temperature drops by 20 °C (36 °F).
As the Gulf Stream meanders across the North Atlantic from the North American east coast to Western Europe its temperature drops by 20 °C (36 °F).
Path of the thermohaline circulation. Purple paths represent deep-water currents, while blue paths represent surface currents.
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).[6]

From October to June the surface is usually covered with sea ice in the Labrador Sea, Denmark Strait, and Baltic Sea.[6]

The Coriolis effect circulates North Atlantic water in a clockwise direction, whereas South Atlantic water circulates counter-clockwise. The south tides in the Atlantic Ocean are semi-diurnal; that is, two high tides occur every 24 lunar hours. In latitudes above 40° North some east–west oscillation, known as the North Atlantic oscillation, occurs.[6]

Salinity

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.[6]

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.[34]

Water masses

Temperature-salinity characteristics for Atlantic water masses[35]
Water mass Temperature Salinity
Upper waters (0–500 m or 0–1,600 ft)
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 (500–1,500 m or 1,600–4,900 ft)
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 (1,500 m–bottom or 4,900 ft–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 to −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 northernmost 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.[36]

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.[36]

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.[37] 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.[38]

Gyres

North Atlantic    gyre
 North Atlantic    gyre
 North Atlantic    gyre
 IndianOcean gyre
 NorthPacificgyre
 SouthPacificgyre
 South Atlantic        gyre



 World map of the five major ocean gyres
North Atlantic
gyre
North Atlantic
gyre
North Atlantic
gyre
Indian
Ocean
gyre
North
Pacific
gyre
South
Pacific
gyre
South Atlantic
        gyre
North Atlantic    gyre
 North Atlantic    gyre
 North Atlantic    gyre
 IndianOcean gyre
 NorthPacificgyre
 SouthPacificgyre
 South Atlantic        gyre



 World map of the five major ocean gyres
World 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.[6]

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.[39]

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.
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.[40] 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 becomes part of the deep portion of the North Atlantic Deep Water (NADW). The NADW, in its turn, feeds 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.[41]

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 the Falkland Islands. Both these currents receive some contribution from the Indian Ocean. On the African east coast, the small cyclonic Angola Gyre lies embedded in the large subtropical gyre.[42] The southern subtropical gyre is partly masked by a wind-induced Ekman layer. The residence time of the gyre is 4.4–8.5 years. North Atlantic Deep Water flows southward below the thermocline of the subtropical gyre.[43]

Sargasso Sea

Approximate extent of the Sargasso SeaSargassum fish (Histrio histrio)
Approximate extent of the Sargasso Sea
Approximate extent of the Sargasso SeaSargassum fish (Histrio histrio)
Sargassum fish (Histrio histrio)

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 millions of years.[44]

Other species endemic to the Sargasso Sea include the sargassum fish, a predator with algae-like appendages which hovers motionless among the Sargassum. Fossils of similar fishes have been found in fossil bays of the former Tethys Ocean, in what 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.[44] 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 where it migrated over Sicily to the Central Atlantic where it evolved into modern species of the Sargasso Sea.[45]

The location of the spawning ground for European eels remained unknown for decades. In the early 19th century it was discovered that the southern Sargasso Sea is the spawning ground for both the European and American eel and that the former migrate more than 5,000 km (3,100 mi) and the latter 2,000 km (1,200 mi). Ocean currents such as the Gulf Stream transport eel larvae from the Sargasso Sea to foraging areas in North America, Europe, and Northern Africa.[46] Recent but disputed research suggests that eels possibly use Earth's magnetic field to navigate through the ocean both as larvae and as adults.[47]

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Thermohaline circulation

Thermohaline circulation

Thermohaline circulation (THC) is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes. The adjective thermohaline derives from thermo- referring to temperature and -haline referring to salt content, factors which together determine the density of sea water. Wind-driven surface currents travel polewards from the equatorial Atlantic Ocean, cooling en route, and eventually sinking at high latitudes. This dense water then flows into the ocean basins. While the bulk of it upwells in the Southern Ocean, the oldest waters upwell in the North Pacific. Extensive mixing therefore takes place between the ocean basins, reducing differences between them and making the Earth's oceans a global system. The water in these circuits transport both energy and mass around the globe. As such, the state of the circulation has a large impact on the climate of the Earth.

Labrador Sea

Labrador Sea

The Labrador Sea is an arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland. The sea is flanked by continental shelves to the southwest, northwest, and northeast. It connects to the north with Baffin Bay through the Davis Strait. It is a marginal sea of the Atlantic.

Denmark Strait

Denmark Strait

The Denmark Strait or Greenland Strait is an oceanic strait between Greenland to its northwest and Iceland to its southeast. The Norwegian island of Jan Mayen lies northeast of the strait.

Tide

Tide

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and are also caused by the Earth and Moon orbiting one another.

40th parallel north

40th parallel north

The 40th parallel north is a circle of latitude that is 40 degrees north of the Earth's equatorial plane. It crosses Europe, the Mediterranean Sea, Asia, the Pacific Ocean, North America, and the Atlantic Ocean.

North Atlantic oscillation

North Atlantic oscillation

The North Atlantic Oscillation (NAO) is a weather phenomenon over the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level (SLP) between the Icelandic Low and the Azores High. Through fluctuations in the strength of the Icelandic Low and the Azores High, it controls the strength and direction of westerly winds and location of storm tracks across the North Atlantic.

Salinity

Salinity

Salinity is the saltiness or amount of salt dissolved in a body of water, called saline water. It is usually measured in g/L or g/kg.

Sea ice

Sea ice

Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface. Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world's sea ice is enclosed within the polar ice packs in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, including the ocean's ecosystems. Due to the action of winds, currents and temperature fluctuations, sea ice is very dynamic, leading to a wide variety of ice types and features. Sea ice may be contrasted with icebergs, which are chunks of ice shelves or glaciers that calve into the ocean. Depending on location, sea ice expanses may also incorporate icebergs.

25th parallel north

25th parallel north

The 25th parallel north is a circle of latitude that is 25 degrees north of the Earth's equatorial plane. It crosses Africa, Asia, the Indian Ocean, the Pacific Ocean, North America and the Atlantic Ocean.

25th parallel south

25th parallel south

The 25th parallel south is a circle of latitude that is 25 degrees south of the Earth's equatorial plane, just south of the Tropic of Capricorn. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Australasia, the Pacific Ocean and South America.

15th parallel north

15th parallel north

The 15th parallel north is a circle of latitude that is 15 degrees north of the Earth's equatorial plane. It crosses the Saharan fringe in Africa, three key peninsulas of Asia, the Pacific Ocean, an isthmus of Central America, the southern Caribbean and the Atlantic Ocean.

North Atlantic Deep Water

North Atlantic Deep Water

North Atlantic Deep Water (NADW) is a deep water mass formed in the North Atlantic Ocean. Thermohaline circulation of the world's oceans involves the flow of warm surface waters from the southern hemisphere into the North Atlantic. Water flowing northward becomes modified through evaporation and mixing with other water masses, leading to increased salinity. When this water reaches the North Atlantic it cools and sinks through convection, due to its decreased temperature and increased salinity resulting in increased density. NADW is the outflow of this thick deep layer, which can be detected by its high salinity, high oxygen content, nutrient minima, high 14C/12C, and chlorofluorocarbons (CFCs).

Climate

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.
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.[6]

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 the climate by transporting warm and cold waters to other regions. The winds that are cooled or warmed when blowing over these currents influence adjacent land areas.[6]

The Gulf Stream and its northern extension towards Europe, the North Atlantic Drift is thought to have at least some influence on climate. For example, the Gulf Stream helps moderate winter temperatures along the coastline of southeastern North America, keeping it warmer in winter along the coast than inland areas. The Gulf Stream also keeps extreme temperatures from occurring on the Florida Peninsula. In the higher latitudes, the North Atlantic Drift, warms the atmosphere over the oceans, keeping the British Isles and north-western Europe mild and cloudy, and not severely cold in winter, like other locations at the same high latitude. The cold water currents contribute to heavy fog off the coast of eastern Canada (the Grand Banks of Newfoundland area) and Africa's north-western coast. In general, winds transport moisture and air over land areas.[6]

Natural hazards

Iceberg A22A in the South Atlantic Ocean
Iceberg A22A in the South Atlantic Ocean

Every winter, the Icelandic Low produces frequent storms. Icebergs are common from early February to the end of July across the shipping lanes near the Grand Banks of Newfoundland. The ice season is longer in the polar regions, but there is little shipping in those areas.[48]

Hurricanes are a hazard in the western parts of the North Atlantic during the summer and autumn. Due to a consistently strong wind shear and a weak Intertropical Convergence Zone, South Atlantic tropical cyclones are rare.[49]

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Trade winds

Trade winds

The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere, strengthening during the winter and when the Arctic oscillation is in its warm phase. Trade winds have been used by captains of sailing ships to cross the world's oceans for centuries. They enabled colonial expansion into the Americas, and trade routes to become established across the Atlantic Ocean and the Pacific Ocean.

Gulf Stream

Gulf Stream

The Gulf Stream, together with its northern extension the North Atlantic Drift, is a warm and swift Atlantic ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida and up the eastern coastline of the United States then veers east near 36 latitude and moves toward Northwest Europe as the North Atlantic Current. The process of western intensification causes the Gulf Stream to be a northwards accelerating current off the east coast of North America. At about 40°0′N 30°0′W, it splits in two, with the northern stream, the North Atlantic Drift, crossing to Northern Europe and the southern stream, the Canary Current, recirculating off West Africa.

North Atlantic Current

North Atlantic Current

The North Atlantic Current (NAC), also known as North Atlantic Drift and North Atlantic Sea Movement, is a powerful warm western boundary current within the Atlantic Ocean that extends the Gulf Stream northeastward.

Grand Banks of Newfoundland

Grand Banks of Newfoundland

The Grand Banks of Newfoundland are a series of underwater plateaus south-east of the island of Newfoundland on the North American continental shelf. The Grand Banks are one of the world's richest fishing grounds, supporting Atlantic cod, swordfish, haddock and capelin, as well as shellfish, seabirds and sea mammals.

Icelandic Low

Icelandic Low

The Icelandic Low is a semi-permanent centre of low atmospheric pressure found between Iceland and southern Greenland and extending in the Northern Hemisphere winter into the Barents Sea. In the summer, it weakens and splits into two centres, one near Davis Strait, Labrador, and the other west of Iceland. It is a principal centre of action in the atmosphere circulation of the Northern Hemisphere, associated with frequent cyclone activity. It forms one pole of the North Atlantic oscillation, the other being the Azores High.

Iceberg

Iceberg

An iceberg is a piece of freshwater ice more than 15 m long that has broken off a glacier or an ice shelf and is floating freely in open (salt) water. Smaller chunks of floating glacially-derived ice are called "growlers" or "bergy bits". The sinking of the Titanic in 1912 led to the formation of the International Ice Patrol in 1914. Much of an iceberg is below the surface, which led to the expression "tip of the iceberg" to illustrate a small part of a larger unseen issue. Icebergs are considered a serious maritime hazard.

Atlantic hurricane

Atlantic hurricane

An Atlantic hurricane, also known as tropical storm or simply hurricane, is a tropical cyclone that forms in the Atlantic Ocean, primarily between the months of June and November. A hurricane differs from a cyclone or typhoon only on the basis of location. A hurricane is a storm that occurs in the Atlantic Ocean and northeastern Pacific Ocean, a typhoon occurs in the northwestern Pacific Ocean, and a cyclone occurs in the South Pacific Ocean or Indian Ocean.

Wind shear

Wind shear

Wind shear, sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal wind shear. Vertical wind shear is a change in wind speed or direction with a change in altitude. Horizontal wind shear is a change in wind speed with a change in lateral position for a given altitude.

Intertropical Convergence Zone

Intertropical Convergence Zone

The Intertropical Convergence Zone, known by sailors as the doldrums or the calms because of its monotonous windless weather, is the area where the northeast and the southeast trade winds converge. It encircles Earth near the thermal equator though its specific position varies seasonally. When it lies near the geographic Equator, it is called the near-equatorial trough. Where the ITCZ is drawn into and merges with a monsoonal circulation, it is sometimes referred to as a monsoon trough, a usage that is more common in Australia and parts of Asia.

South Atlantic tropical cyclone

South Atlantic tropical cyclone

South Atlantic tropical cyclones are unusual weather events that occur in the Southern Hemisphere. Strong wind shear, which disrupts the formation of cyclones, as well as a lack of weather disturbances favorable for development in the South Atlantic Ocean, make any strong tropical system extremely rare, and Hurricane Catarina in 2004 is the only recorded South Atlantic hurricane in history. Storms can develop year-round in the South Atlantic, with activity peaking during the months from November through May. Since 2011, the Brazilian Navy Hydrographic Center has assigned names to tropical and subtropical systems in the western side of the basin, near the eastern coast of Brazil, when they have sustained wind speeds of at least 65 km/h (40 mph), the generally accepted minimum sustained wind speed for a disturbance to be designated as a tropical storm in the North Atlantic basin. Below is a list of notable South Atlantic tropical and subtropical cyclones.

Geology and plate tectonics

The Atlantic Ocean is underlain mostly by dense mafic oceanic crust made up of basalt and gabbro and overlain by fine clay, silt and siliceous ooze on the abyssal plain. The continental margins and continental shelf mark lower density, but greater thickness felsic continental rock that is often much older than that of the seafloor. The oldest oceanic crust in the Atlantic is up to 145 million years and situated off the west coast of Africa and east coast of North America, or on either side of the South Atlantic.[50]

In many places, the continental shelf and continental slope are covered in thick sedimentary layers. For instance, on the North American side of the ocean, large carbonate deposits formed in warm shallow waters such as Florida and the Bahamas, while coarse river outwash sands and silt are common in shallow shelf areas like the Georges Bank. Coarse sand, boulders, and rocks were transported into some areas, such as off the coast of Nova Scotia or the Gulf of Maine during the Pleistocene ice ages.[51]

Central Atlantic

Opening of the Central Atlantic 200-170 Ma
Opening of the Central Atlantic 200-170 Ma
Opening of the Central Atlantic 200-170 Ma

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.[52]

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.[53] 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.[54]

The formation of the Central American Isthmus closed the Central American Seaway at the end of the Pliocene 2.8 Ma ago. The formation of the isthmus resulted in the migration and extinction of many land-living animals, known as the Great American Interchange, but the closure of the seaway resulted in a "Great American Schism" as it affected ocean currents, salinity, and temperatures in both the Atlantic and Pacific. Marine organisms on both sides of the isthmus became isolated and either diverged or went extinct.[55]

North Atlantic

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.[56]

Seafloor spreading led to the extension of the crust and formations of troughs and sedimentary basins. 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. [57]

Spreading began opening the Labrador Sea around 61 million years ago, continuing until 36 million years ago. Geologists distinguish two magmatic phases. One from 62 to 58 million years ago predates the separation of Greenland from northern Europe while the second from 56 to 52 million years ago happened as the separation occurred.

Iceland began to form 62 million years ago due to a particularly concentrated mantle plume. 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. [58] The opening of the North Atlantic caused significant uplift of continental crust along the coast. For instance, in spite of 7 km thick basalt, Gunnbjorn Field in East Greenland is the highest point on the island, elevated enough that it exposes older Mesozoic sedimentary rocks at its base, similar to old lava fields above sedimentary rocks in the uplifted Hebrides of western Scotland. [59]

The North Atlantic Ocean contains about 810 seamounts, most of them situated along the Mid-Atlantic Ridge.[60] The OSPAR database (Convention for the Protection of the Marine Environment of the North-East Atlantic) mentions 104 seamounts: 74 within the national Exclusive economic zone. Of these seamounts, 46 are located close to the Iberian Peninsula.

South Atlantic

The opening of the South Atlantic
The opening of the South Atlantic
The opening of the South Atlantic
The opening of the South Atlantic

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.[61][62] 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.[61] Intra-continental rifts and deformations have also been introduced to subdivide both continental plates into sub-plates.[63]

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.[64]

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 and 121 Ma and 90–60 Ma.[64]

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.[63]

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.[63]

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 seafloor spreading in this segment and consequent opening of the Equatorial Atlantic Gateway (EAG) to the period 120–96 Ma.[65][66] This final stage, nevertheless, coincided with or resulted in the end of continental extension in Africa.[63]

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. First, small ocean basins opened and a shallow gateway appeared during the Middle Eocene. 34–30 Ma a deeper seaway developed, followed by an Eocene–Oligocene climatic deterioration and the growth of the Antarctic ice sheet.[67]

Closure of the Atlantic

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. Together these three tectonic forces are slowly 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 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.[68]

Discover more about Geology and plate tectonics related topics

Basalt

Basalt

Basalt is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a rocky planet or moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of Venus, which cover ~80% of the surface, are basaltic; the lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars.

Gabbro

Gabbro

Gabbro is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is chemically equivalent to rapid-cooling, fine-grained basalt. Much of the Earth's oceanic crust is made of gabbro, formed at mid-ocean ridges. Gabbro is also found as plutons associated with continental volcanism. Due to its variant nature, the term gabbro may be applied loosely to a wide range of intrusive rocks, many of which are merely "gabbroic". By rough analogy, gabbro is to basalt as granite is to rhyolite.

Felsic

Felsic

In geology, felsic is a modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz. It is contrasted with mafic rocks, which are relatively richer in magnesium and iron. Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Felsic magma or lava is higher in viscosity than mafic magma/lava.

Georges Bank

Georges Bank

Georges Bank is a large elevated area of the sea floor between Cape Cod, Massachusetts, and Cape Sable Island, Nova Scotia (Canada). It separates the Gulf of Maine from the Atlantic Ocean.

Gulf of Maine

Gulf of Maine

The Gulf of Maine is a large gulf of the Atlantic Ocean on the east coast of North America. It is bounded by Cape Cod at the eastern tip of Massachusetts in the southwest and by Cape Sable Island at the southern tip of Nova Scotia in the northeast. The gulf includes the entire coastlines of the U.S. states of New Hampshire and Maine, as well as Massachusetts north of Cape Cod, and the southern and western coastlines of the Canadian provinces of New Brunswick and Nova Scotia, respectively.

Extinction event

Extinction event

An extinction event is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. It occurs when the rate of extinction increases with respect to the background extinction rate and the rate of speciation. Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty. These differences stem from disagreement as to what constitutes a "major" extinction event, and the data chosen to measure past diversity.

Dike (geology)

Dike (geology)

A dike or dyke, in geological usage, is a sheet of rock that is formed in a fracture of a pre-existing rock body. Dikes can be either magmatic or sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. Clastic dikes are formed when sediment fills a pre-existing crack.

Aquatic sill

Aquatic sill

An aquatic sill is a sea floor barrier of relatively shallow depth that restricts water movement between benthic zones of an oceanic basin or lake bottom. There are roughly 400 sills in the Earth's oceans, covering 0.01% of the seafloor. A classic example is the Strait of Gibraltar Gateway between the Mediterranean sea and the Atlantic Ocean.

Central American Seaway

Central American Seaway

The Central American Seaway was a body of water that once separated North America from South America. It formed during the Jurassic during the breakup of the supercontinent Pangaea, and closed when the Isthmus of Panama was formed by volcanic activity in the late Pliocene.

Great American Interchange

Great American Interchange

The Great American Biotic Interchange, also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which land and freshwater fauna migrated from North America via Central America to South America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor and bridged the formerly separated continents. Although earlier dispersals had occurred, probably over water, the migration accelerated dramatically about 2.7 million years (Ma) ago during the Piacenzian age. It resulted in the joining of the Neotropic and Nearctic biogeographic realms definitively to form the Americas. The interchange is visible from observation of both biostratigraphy and nature (neontology). Its most dramatic effect is on the zoogeography of mammals, but it also gave an opportunity for reptiles, amphibians, arthropods, weak-flying or flightless birds, and even freshwater fish to migrate. Coastal and marine biota, however, was affected in the opposite manner; the formation of the Central American Isthmus caused what has been termed the Great American Schism, with significant diversification and extinction occurring as a result of the isolation of the Caribbean from the Pacific.

Eurasian Basin

Eurasian Basin

The Eurasian Basin, or Eurasia Basin, is one of the two major basins into which the Arctic Basin of the Arctic Ocean is split by the Lomonosov Ridge. The Eurasia Basin may be seen as an extension of the North Atlantic Basin through Fram Strait. It is further split by the mid-ocean Gakkel Ridge into the Nansen Basin and the Amundsen Basin. The latter basin is the deepest one of the Arctic Ocean and the geographic North Pole is located there.

Iapetus Ocean

Iapetus Ocean

The Iapetus Ocean was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale. The Iapetus Ocean was situated in the southern hemisphere, between the paleocontinents of Laurentia, Baltica and Avalonia. The ocean disappeared with the Acadian, Caledonian and Taconic orogenies, when these three continents joined to form one big landmass called Euramerica. The "southern" Iapetus Ocean has been proposed to have closed with the Famatinian and Taconic orogenies, meaning a collision between Western Gondwana and Laurentia.

History

Human origin

Humans evolved in Africa; first by diverging from other apes around 7 mya; then developing stone tools around 2.6 mya; to finally evolve as modern humans around 200 kya. 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. During the latest glacial stages, the now-submerged plains of the Agulhas Bank were exposed above sea level, extending the South African coastline farther south by hundreds of kilometers. 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 GCFR is delimited to the north by the Cape Fold Belt and the limited space south of it resulted in the development of social networks out of which complex Stone Age technologies emerged.[69] Human history thus begins on the coasts of South Africa where the Atlantic Benguela Upwelling and Indian Ocean Agulhas Current meet to produce an intertidal zone on which shellfish, fur seal, fish and sea birds provided the necessary protein sources.[70] The African origin of this modern behaviour is evidenced by 70,000 years-old engravings from Blombos Cave, South Africa.[71]

Old World

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. This group of people not only expanded over the whole of Africa, but also started to disperse out of Africa into Asia, Europe, and Australasia around 65,000 years ago and quickly replaced the archaic humans in these regions.[72] 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. Following rapid climate changes at the end of the LGM this region was repopulated by Magdalenian culture. Other hunter-gatherers followed in waves interrupted by large-scale hazards such as the Laacher See volcanic eruption, the inundation of Doggerland (now the North Sea), and the formation of the Baltic Sea.[73] The European coasts of the North Atlantic were permanently populated about 9–8.5 thousand years ago.[74]

This human dispersal left abundant traces along the coasts of the Atlantic Ocean. 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). The MSA population was small and dispersed and the rate of their reproduction and exploitation was less intense than those of later generations. 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.[75]

Excavation of the Ertebølle middens in 1880
Excavation of the Ertebølle middens in 1880

The same development can be seen in Europe. In La Riera Cave (23–13 kya) in Asturias, Spain, only some 26,600 molluscs were deposited over 10 kya. In contrast, 8–7 kya-old shell middens in Portugal, Denmark, and Brazil generated thousands of tons of debris and artefacts. The Ertebølle middens in Denmark, for example, accumulated 2,000 m3 (71,000 cu ft) of shell deposits representing some 50 million molluscs over only a thousand years. This intensification in the exploitation of marine resources has been described as accompanied by new technologies — such as boats, harpoons, and fish-hooks — because many caves found in the Mediterranean and on the European Atlantic coast have increased quantities of marine shells in their upper levels and reduced quantities in their lower. The earliest exploitation, however, took place on the now submerged shelves, and most settlements now excavated were then located several kilometers from these shelves. The reduced quantities of shells in the lower levels can represent the few shells that were exported inland.[76]

New World

During the LGM the Laurentide Ice Sheet covered most of northern North America while Beringia connected Siberia to Alaska. 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."[77] Others later proposed a "three-wave" migration over the Bering Land Bridge.[78] These hypotheses remained the long-held view regarding the settlement of the Americas, a view challenged by more recent archaeological discoveries: the oldest archaeological sites in the Americas have been found in South America; sites in north-east Siberia report virtually no human presence there during the LGM; and most Clovis artefacts have been found in eastern North America along the Atlantic coast.[79] 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. Contradictory data from archaeology and genetics will most likely deliver future hypotheses that will, eventually, confirm each other.[80] 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.[81] Early settlements across the Atlantic have been suggested by alternative theories, ranging from purely hypothetical to mostly disputed, including the Solutrean hypothesis and some of the Pre-Columbian trans-oceanic contact theories.

Based on the medieval Íslendingasögur sagas, including the Grœnlendinga saga, this interpretative map of the "Norse World" shows that Norse knowledge of the Americas and the Atlantic remained limited.
Based on the medieval Íslendingasögur sagas, including the Grœnlendinga saga, this interpretative map of the "Norse World" shows that Norse knowledge of the Americas and the Atlantic remained limited.

The Norse settlement of the Faroe Islands and Iceland began during the 9th and 10th centuries. A settlement on Greenland was established before 1000 CE, but contact with it was lost in 1409 and it was finally abandoned during the early Little Ice Age. This setback was caused by a range of factors: an unsustainable economy resulted in erosion and denudation, while conflicts with the local Inuit resulted in the failure to adapt their Arctic technologies; a colder climate resulted in starvation, and the colony got economically marginalized as the Great Plague and Barbary pirates harvested its victims on Iceland in the 15th century.[82] 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. This did not last, however, and temperatures quickly dropped; at 1080 CE summer temperatures had reached a maximum of 5 °C (41 °F). 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.[83]

Atlantic World

The Atlantic Gyres influenced the Portuguese discoveries and trading port routes, here shown in the India Run ("Carreira da Índia"), which would be developed in subsequent years.
The Atlantic Gyres influenced the Portuguese discoveries and trading port routes, here shown in the India Run ("Carreira da Índia"), which would be developed in subsequent years.

Christopher Columbus reached the Americas in 1492 under Spanish flag.[84] Six years later Vasco da Gama reached India under the Portuguese flag, by navigating south around the Cape of Good Hope, thus proving that the Atlantic and Indian Oceans are connected. In 1500, in his voyage to India following Vasco da Gama, Pedro Alvares Cabral reached Brazil, taken by the currents of the South Atlantic Gyre. Following these explorations, Spain and Portugal quickly conquered and colonized large territories in the New World and forced the Amerindian population into slavery in order to exploit the vast quantities of silver and gold they found. Spain and Portugal monopolized this trade in order to keep other European nations out, but conflicting interests nevertheless led to a series of Spanish-Portuguese wars. A peace treaty mediated by the Pope divided the conquered territories into Spanish and Portuguese sectors while keeping other colonial powers away. 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. They could explore the convoys leaving the Americas because prevailing winds and currents made the transport of heavy metals slow and predictable.[84]

Embarked and disembarked slaves in the Atlantic slave trade 1525–1863 (first and last slave voyages)
Embarked and disembarked slaves in the Atlantic slave trade 1525–1863 (first and last slave voyages)

In the colonies of the Americas, depredation, smallpox and others diseases, and slavery quickly reduced the indigenous population of the Americas to the extent that the Atlantic slave trade had to be introduced to replace them — a trade that became the norm and an integral part of the colonization. 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. 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.[85][86]

From Columbus to the Industrial Revolution Trans-Atlantic trade, including colonialism and slavery, became crucial for Western Europe. For European countries with direct access to the Atlantic (including Britain, France, the Netherlands, Portugal, and Spain) 1500–1800 was a period of sustained growth during which these countries grew richer than those in Eastern Europe and Asia. Colonialism evolved as part of the Trans-Atlantic trade, but this trade also strengthened the position of merchant groups at the expense of monarchs. Growth was more rapid in non-absolutist countries, such as Britain and the Netherlands, and more limited in absolutist monarchies, such as Portugal, Spain, and France, where profit mostly or exclusively benefited the monarchy and its allies.[87]

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. Likewise, GDP doubled in Atlantic countries but rose by only 30% in the rest of Europe. By end of the 17th century, the volume of the Trans-Atlantic trade had surpassed that of the Mediterranean trade.[87]

Upon completion in 1858, the first successful Transatlantic telegraph cable was laid out beneath the Atlantic Ocean by the United States and Britain.

The Atlantic Ocean became the scene of one of the longest continuous naval military camapaigns throughout World War II, from 1939 to 1945.

Discover more about History related topics

Human evolution

Human evolution

Human evolution is the evolutionary process within the history of primates that led to the emergence of Homo sapiens as a distinct species of the hominid family, which includes all the great apes. This process involved the gradual development of traits such as human bipedalism, dexterity and complex language, as well as interbreeding with other hominins, indicating that human evolution was not linear but weblike. The study of human evolution involves several scientific disciplines, including physical and evolutionary anthropology, paleontology, and genetics.

Behavioral modernity

Behavioral modernity

Behavioral modernity is a suite of behavioral and cognitive traits that distinguishes current Homo sapiens from other anatomically modern humans, hominins, and primates. Most scholars agree that modern human behavior can be characterized by abstract thinking, planning depth, symbolic behavior, music and dance, exploitation of large game, and blade technology, among others. Underlying these behaviors and technological innovations are cognitive and cultural foundations that have been documented experimentally and ethnographically by evolutionary and cultural anthropologists. These human universal patterns include cumulative cultural adaptation, social norms, language, and extensive help and cooperation beyond close kin.

Cape Floristic Region

Cape Floristic Region

The Cape Floral Region is a floristic region located near the southern tip of South Africa. It is the only floristic region of the Cape Floristic Kingdom, and includes only one floristic province, known as the Cape Floristic Province.

Agulhas Bank

Agulhas Bank

The Agulhas Bank is a broad, shallow part of the southern African continental shelf which extends up to 250 km (160 mi) south of Cape Agulhas before falling steeply to the abyssal plain.

Cape Fold Belt

Cape Fold Belt

The Cape Fold Belt is a fold and thrust belt of late Paleozoic age, which affected the sequence of sedimentary rock layers of the Cape Supergroup in the southwestern corner of South Africa. It was originally continuous with the Ventana Mountains near Bahía Blanca in Argentina, the Pensacola Mountains, the Ellsworth Mountains and the Hunter-Bowen orogeny in eastern Australia. The rocks involved are generally sandstones and shales, with the shales persisting in the valley floors while the erosion resistant sandstones form the parallel ranges, the Cape Fold Mountains, which reach a maximum height of 2325 m at Seweweekspoortpiek.

Benguela Current

Benguela Current

The Benguela Current is the broad, northward flowing ocean current that forms the eastern portion of the South Atlantic Ocean gyre. The current extends from roughly Cape Point in the south, to the position of the Angola-Benguela front in the north, at around 16°S. The current is driven by the prevailing south easterly trade winds. Inshore of the Benguela Current proper, the south easterly winds drive coastal upwelling, forming the Benguela Upwelling System. The cold, nutrient rich waters that upwell from around 200–300 m (656–984 ft) depth in turn fuel high rates of phytoplankton growth, and sustain the productive Benguela ecosystem.

Agulhas Current

Agulhas Current

The Agulhas Current is the western boundary current of the southwest Indian Ocean. It flows south along the east coast of Africa from 27°S to 40°S. It is narrow, swift and strong. It is suggested that it is the largest western boundary current in the world ocean, with an estimated net transport of 70 sverdrups, as western boundary currents at comparable latitudes transport less — Brazil Current, Gulf Stream, Kuroshio.

Blombos Cave

Blombos Cave

Blombos Cave is an archaeological site located in Blombos Private Nature Reserve, about 300 km east of Cape Town on the Southern Cape coastline, South Africa. The cave contains Middle Stone Age (MSA) deposits currently dated at between c. 100,000 and 70,000 years Before Present (BP), and a Late Stone Age sequence dated at between 2000 and 300 years BP. The cave site was first excavated in 1991 and field work has been conducted there on a regular basis since 1997, and is ongoing.

Last Glacial Maximum

Last Glacial Maximum

The Last Glacial Maximum (LGM), also referred to as the Late Glacial Maximum, was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent 26 ka - 20 ka, during an interval of low obliquity. Ice sheets covered much of Northern North America, Northern Europe, and Asia and profoundly affected Earth's climate by causing a major expansion of deserts, along with a large drop in sea levels. Based on changes in position of ice sheet margins dated via terrestrial cosmogenic nuclides and radiocarbon dating, growth of ice sheets commenced 33,000 years ago and maximum coverage was between 26,500 years and 19–20,000 years ago, when deglaciation commenced in the Northern Hemisphere, causing an abrupt rise in sea level. Decline of the West Antarctica ice sheet occurred between 14,000 and 15,000 years ago, consistent with evidence for another abrupt rise in the sea level about 14,500 years ago. Glacier fluctuations around the Strait of Magellan suggest the peak in glacial surface area was constrained to between 25,200 and 23,100 years ago. Continental ice sheets never reached their isostatic equilibrium during the LGM, as evidenced by high variability in ice volume over short spans of time.

Laacher See

Laacher See

Laacher See, also known as Lake Laach or Laach Lake, is a volcanic caldera lake with a diameter of 2 km (1.2 mi) in Rhineland-Palatinate, Germany, about 24 km (15 mi) northwest of Koblenz, 37 km (23 mi) south of Bonn, and 8 km (5.0 mi) west of Andernach. It is in the Eifel mountain range, and is part of the East Eifel volcanic field within the larger Volcanic Eifel. The lake was formed by a Plinian eruption approximately 13,000 years BP with a Volcanic Explosivity Index (VEI) of 6, on the same scale as the Pinatubo eruption of 1991.

Doggerland

Doggerland

Doggerland was an area of land, now submerged beneath the North Sea, that connected Britain to continental Europe. It was flooded by rising sea levels around 6500–6200 BCE. The flooded land is known as the Dogger Littoral. Geological surveys have suggested that it stretched from what is now the east coast of Great Britain to what are now the Netherlands, the western coast of Germany and the Danish peninsula of Jutland. It was probably a rich habitat with human habitation in the Mesolithic period, although rising sea levels gradually reduced it to low-lying islands before its final submergence, possibly following a tsunami caused by the Storegga Slide. Doggerland was named after the Dogger Bank, which in turn was named after 17th-century Dutch fishing boats called doggers.

Baltic Sea

Baltic Sea

The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain.

Economy

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.[6]

Cod fishery in Norway
Cod fishery in Norway

The Atlantic harbors petroleum and gas fields, fish, marine mammals (seals and whales), sand and gravel aggregates, placer deposits, polymetallic nodules, and precious stones.[88] 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.[89]

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.[6]

Fisheries

The shelves of the Atlantic hosts one of the world's richest fishing resources. 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.[6] Fisheries have, however, undergone significant changes since the 1950s and global catches can now be divided into three groups of which only two are observed in the Atlantic: fisheries in the Eastern Central and South-West Atlantic oscillate around a globally stable value, the rest of the Atlantic is in overall decline following historical peaks. The third group, "continuously increasing trend since 1950", is only found in the Indian Ocean and Western Pacific.[90]

UN FAO partitioned Atlantic in major fishing areas:

Banks of the North-East Atlantic
Banks of the North-East Atlantic
North-East Atlantic

North-East Atlantic is schematically limited to the 42°00' west longitude except around Greenland and at south to 36°00' north latitude; and 68°30' east longitude at the east, according to FAO fisheries definition and include various seas and/or subareas: Barents Sea, Norwegian Sea, Spitzbergen, Bear Island, Skagerrak, Kattegat, Sound, Belt Sea, Baltic Sea, North Sea, Iceland, Faroes Grounds, Rockall, Northwest Coast of Scotland, North Ireland, Irish Sea, West of Ireland, Porcupine Bank, Eastern and Western English Channel, Bay of Biscay, Portuguese Waters, Azores Grounds and Northeast Atlantic South.

In the North-East Atlantic total catches decreased between the mid-1970s and the 1990s and reached 8.7 million tons in 2013. Blue whiting reached a 2.4 million tons peak in 2004 but was down to 628,000 tons in 2013. Recovery plans for cod, sole, and plaice have reduced mortality in these species. Arctic cod reached its lowest levels in the 1960s–1980s but is now recovered. Arctic saithe and haddock are considered fully fished; Sand eel is overfished as was capelin which has now recovered to fully fished. Limited data makes the state of redfishes and deep-water species difficult to assess but most likely they remain vulnerable to overfishing. Stocks of northern shrimp and Norwegian lobster are in good condition. In the North-East Atlantic 21% of stocks are considered overfished.[90]
This zone makes almost three quarters (72.8 %) of European Union fishing catches in 2020. Main fishing EU countries are Denmark, France, the Netherlands and Spain. Most common species include herring, mackerel and sprats.
Banks of the North-West Atlantic
Banks of the North-West Atlantic
North-West Atlantic
In the North-West Atlantic landings have 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 weak signs of recovery, including Greenland halibut, yellowtail flounder, Atlantic halibut, haddock, spiny dogfish, while other stocks shown no such signs, including cod, witch flounder, and redfish. Stocks of invertebrates, in contrast, remain at record levels of abundance. 31% of stocks are overfished in the North-west Atlantic.[90]
Capture of Atlantic north-west cod in million tons
Capture of Atlantic north-west cod in million tons

In 1497, John Cabot became the first Western European since the Vikings to explore mainland North America and one of his major discoveries was the abundant resources of Atlantic cod off Newfoundland. Referred to as "Newfoundland Currency" this discovery yielded some 200 million tons of fish over five centuries. In the late 19th and early 20th centuries new fisheries started to exploit haddock, mackerel, and lobster. From the 1950s to the 1970s the introduction of European and Asian distant-water fleets in the area dramatically increased the fishing capacity and the number of exploited species. It also expanded the exploited areas from near-shore to the open sea and to great depths to include deep-water species such as redfish, Greenland halibut, witch flounder, and grenadiers. Overfishing in the area was recognised as early as the 1960s but, because this was occurring on international waters, it took until the late 1970s before any attempts to regulate was made. In the early 1990s, this finally resulted in the collapse of the Atlantic northwest cod fishery. The population of a number of deep-sea fishes also collapsed in the process, including American plaice, redfish, and Greenland halibut, together with flounder and grenadier.[91]

Eastern Central Atlantic
In the Eastern Central Atlantic small pelagic fishes constitute about 50% of landings with sardine reaching 0.6–1.0 million tons per year. Pelagic fish stocks are considered fully fished or overfished, with sardines south of Cape Bojador the notable exception. Almost half of the stocks are fished at biologically unsustainable levels. Total catches have been fluctuating since the 1970s; reaching 3.9 million tons in 2013 or slightly less than the peak production in 2010.[90]
Western Central Atlantic
In the Western Central Atlantic, catches have been decreasing since 2000 and reached 1.3 million tons in 2013. 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. Round sardinella was an important species in the 1990s but is now considered overfished. Groupers and snappers are overfished and northern brown shrimp and American cupped oyster are considered fully fished approaching overfished. 44% of stocks are being fished at unsustainable levels.[90]
South-East Atlantic
In the South-East Atlantic catches have decreased from 3.3 million tons in the early 1970s to 1.3 million tons in 2013. Horse mackerel and hake are the most important species, together representing almost half of the landings. Off South Africa and Namibia deep-water hake and shallow-water Cape hake have recovered to sustainable levels since regulations were introduced in 2006 and the states of Southern African pilchard and anchovy have improved to fully fished in 2013.[90]
South-West Atlantic
In the South-West Atlantic, a peak was reached in the mid-1980s and catches now fluctuate between 1.7 and 2.6 million tons. 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. Another important species was the Brazilian sardinella, with a production of 100,000 tons in 2013 it is now considered overfished. Half the stocks in this area are being fished at unsustainable levels: Whitehead's round herring has not yet reached fully fished but Cunene horse mackerel is overfished. The sea snail perlemoen abalone is targeted by illegal fishing and remain overfished.[90]


Discover more about Economy related topics

Cod fisheries

Cod fisheries

Cod fisheries are fisheries for cod. Cod is the common name for fish of the genus Gadus, belonging to the family Gadidae, and this article is confined to three species that belong to this genus: the Atlantic cod, the Pacific cod and the Greenland cod. Although there is a fourth species of the cod genus Gadus, Alaska pollock, it is commonly not called cod and therefore currently not covered here.

Gravel

Gravel

Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone.

Marine debris

Marine debris

Marine debris, also known as marine litter, is human-created waste that has deliberately or accidentally been released in a sea or ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing aground, when it is known as beach litter or tidewrack. Deliberate disposal of wastes at sea is called ocean dumping. Naturally occurring debris, such as driftwood and drift seeds, are also present. With the increasing use of plastic, human influence has become an issue as many types of (petrochemical) plastics do not biodegrade quickly, as would natural or organic materials. The largest single type of plastic pollution (~10 %) and majority of large plastic in the oceans is discarded and lost nets from the fishing industry. Waterborne plastic poses a serious threat to fish, seabirds, marine reptiles, and marine mammals, as well as to boats and coasts.

Incineration

Incineration

Incineration is a waste treatment process that involves the combustion of substances contained in waste materials. Industrial plants for waste incineration are commonly referred to as waste-to-energy facilities. Incineration and other high-temperature waste treatment systems are described as "thermal treatment". Incineration of waste materials converts the waste into ash, flue gas and heat. The ash is mostly formed by the inorganic constituents of the waste and may take the form of solid lumps or particulates carried by the flue gas. The flue gases must be cleaned of gaseous and particulate pollutants before they are dispersed into the atmosphere. In some cases, the heat that is generated by incineration can be used to generate electric power.

Continental shelf

Continental shelf

A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island is known as an insular shelf.

Grand Banks of Newfoundland

Grand Banks of Newfoundland

The Grand Banks of Newfoundland are a series of underwater plateaus south-east of the island of Newfoundland on the North American continental shelf. The Grand Banks are one of the world's richest fishing grounds, supporting Atlantic cod, swordfish, haddock and capelin, as well as shellfish, seabirds and sea mammals.

Georges Bank

Georges Bank

Georges Bank is a large elevated area of the sea floor between Cape Cod, Massachusetts, and Cape Sable Island, Nova Scotia (Canada). It separates the Gulf of Maine from the Atlantic Ocean.

Cape Cod

Cape Cod

Cape Cod is a peninsula extending into the Atlantic Ocean from the southeastern corner of mainland Massachusetts, in the northeastern United States. Its historic, maritime character and ample beaches attract heavy tourism during the summer months. The name Cape Cod, coined in 1602 by Bartholomew Gosnold, is the ninth oldest English place-name in the U.S.

Bahama Banks

Bahama Banks

The Bahama Banks are the submerged carbonate platforms that make up much of the Bahama Archipelago. The term is usually applied in referring to either the Great Bahama Bank around Andros Island, or the Little Bahama Bank of Grand Bahama Island and Great Abaco, which are the largest of the platforms, and the Cay Sal Bank north of Cuba. The islands of these banks are politically part of the Bahamas. Other banks are the three banks of the Turks and Caicos Islands, namely the Caicos Bank of the Caicos Islands, the bank of the Turks Islands, and wholly submerged Mouchoir Bank. Farther southeast are the equally wholly submerged Silver Bank and Navidad Bank north of the Dominican Republic.

Irish Sea

Irish Sea

The Irish Sea is an extensive body of water that separates the islands of Ireland and Great Britain. It is linked to the Celtic Sea in the south by St George's Channel and to the Inner Seas off the West Coast of Scotland in the north by the North Channel. Anglesey, North Wales, is the largest island in the Irish Sea, followed by the Isle of Man. The term Manx Sea may occasionally be encountered.

Bay of Fundy

Bay of Fundy

The Bay of Fundy is a bay between the Canadian provinces of New Brunswick and Nova Scotia, with a small portion touching the U.S. state of Maine. It is an arm of the Gulf of Maine. Its extremely high tidal range is the highest in the world. The name is likely a corruption of the French word fendu, meaning 'split'.

Dogger Bank

Dogger Bank

Dogger Bank is a large sandbank in a shallow area of the North Sea about 100 kilometres (62 mi) off the east coast of England.

Environmental issues

Marine debris strewn over the beaches of the South Atlantic Inaccessible Island
Marine debris strewn over the beaches of the South Atlantic Inaccessible Island

Endangered species

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.[92]

Waste and pollution

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.[93]

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 center of gyres and coastlines, frequently washing aground where it is known as beach litter. The North Atlantic garbage patch is estimated to be hundreds of kilometers across in size.[94]

Other pollution concerns include agricultural and municipal waste. 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.

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. For their own safety, the crew jettisoned two nuclear bombs, which were never recovered.[95]

Climate change

North Atlantic hurricane activity has increased over past decades because of increased sea surface temperature (SST) at tropical latitudes, changes that can be attributed to either the natural Atlantic Multidecadal Oscillation (AMO) or to anthropogenic climate change.[96] A 2005 report indicated that the Atlantic meridional overturning circulation (AMOC) slowed down by 30% between 1957 and 2004.[97] If the AMO were responsible for SST variability, the AMOC would have increased in strength, which is apparently not the case. Furthermore, it is clear from statistical analyses of annual tropical cyclones that these changes do not display multidecadal cyclicity.[96] Therefore, these changes in SST must be caused by human activities.[98]

The ocean mixed layer plays an important role in heat storage over seasonal and decadal time-scales, whereas deeper layers are affected over millennia and have a heat capacity about 50 times that of the mixed layer. This heat uptake provides a time-lag for climate change but it also results in thermal expansion of the oceans which contributes to sea level rise. 21st-century global warming will probably result in an equilibrium sea-level rise five times greater than today, whilst melting of glaciers, including that of the Greenland ice-sheet, expected to have virtually no effect during the 21st century, will probably result in a sea-level rise of 3–6 m over a millennium.[99]

Discover more about Environmental issues related topics

Marine debris

Marine debris

Marine debris, also known as marine litter, is human-created waste that has deliberately or accidentally been released in a sea or ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing aground, when it is known as beach litter or tidewrack. Deliberate disposal of wastes at sea is called ocean dumping. Naturally occurring debris, such as driftwood and drift seeds, are also present. With the increasing use of plastic, human influence has become an issue as many types of (petrochemical) plastics do not biodegrade quickly, as would natural or organic materials. The largest single type of plastic pollution (~10 %) and majority of large plastic in the oceans is discarded and lost nets from the fishing industry. Waterborne plastic poses a serious threat to fish, seabirds, marine reptiles, and marine mammals, as well as to boats and coasts.

Inaccessible Island

Inaccessible Island

Inaccessible Island is a volcanic island located in the South Atlantic Ocean, 31 km (19 mi) south-west of Tristan da Cunha. Its highest point, Cairn Peak, reaches 449 m (1,473 ft), and the island is 12.65 km2 (4.88 sq mi) in area. The volcano was last active six million years ago and is currently extinct.

Manatee

Manatee

Manatees are large, fully aquatic, mostly herbivorous marine mammals sometimes known as sea cows. There are three accepted living species of Trichechidae, representing three of the four living species in the order Sirenia: the Amazonian manatee, the West Indian manatee, and the West African manatee. They measure up to 4.0 metres long, weigh as much as 590 kilograms (1,300 lb), and have paddle-like tails.

Albatross

Albatross

Albatrosses, of the biological family Diomedeidae, are large seabirds related to the procellariids, storm petrels, and diving petrels in the order Procellariiformes. They range widely in the Southern Ocean and the North Pacific. They are absent from the North Atlantic, although fossil remains show they once occurred there and occasional vagrants are found. Albatrosses are among the largest of flying birds, and species of the genus Diomedea have the longest wingspans of any extant birds, reaching up to 3.7 m (12 ft). The albatrosses are usually regarded as falling into four genera, but disagreement exists over the number of species.

Auk

Auk

An auk or alcid is a bird of the family Alcidae in the order Charadriiformes. The alcid family includes the murres, guillemots, auklets, puffins, and murrelets. The family contains 25 extant or recently extinct species that are divided into 11 genera.

Marine pollution

Marine pollution

Marine pollution occurs when substances used or spread by humans, such as industrial, agricultural and residential waste, particles, noise, excess carbon dioxide or invasive organisms enter the ocean and cause harmful effects there. The majority of this waste (80%) comes from land-based activity, although marine transportation significantly contributes as well. Since most inputs come from land, either via the rivers, sewage or the atmosphere, it means that continental shelves are more vulnerable to pollution. Air pollution is also a contributing factor by carrying off iron, carbonic acid, nitrogen, silicon, sulfur, pesticides or dust particles into the ocean. The pollution often comes from nonpoint sources such as agricultural runoff, wind-blown debris, and dust. These nonpoint sources are largely due to runoff that enters the ocean through rivers, but wind-blown debris and dust can also play a role, as these pollutants can settle into waterways and oceans. Pathways of pollution include direct discharge, land runoff, ship pollution, atmospheric pollution and, potentially, deep sea mining.

Fertilizer

Fertilizer

A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Many sources of fertilizer exist, both natural and industrially produced. For most modern agricultural practices, fertilization focuses on three main macro nutrients: nitrogen (N), phosphorus (P), and potassium (K) with occasional addition of supplements like rock flour for micronutrients. Farmers apply these fertilizers in a variety of ways: through dry or pelletized or liquid application processes, using large agricultural equipment or hand-tool methods.

Hypoxia (environmental)

Hypoxia (environmental)

Hypoxia refers to low oxygen conditions. Normally, 20.9% of the gas in the atmosphere is oxygen. The partial pressure of oxygen in the atmosphere is 20.9% of the total barometric pressure. In water, oxygen levels are much lower, approximately 7 ppm or 0.0007% in good quality water, and fluctuate locally depending on the presence of photosynthetic organisms and relative distance to the surface.

Dead zone (ecology)

Dead zone (ecology)

Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes. Hypoxia occurs when dissolved oxygen (DO) concentration falls to or below 2 mg of O2/liter. When a body of water experiences hypoxic conditions, aquatic flora and fauna begin to change behavior in order to reach sections of water with higher oxygen levels. Once DO declines below 0.5 ml O2/liter in a body of water, mass mortality occurs. With such a low concentration of DO, these bodies of water fail to support the aquatic life living there. Historically, many of these sites were naturally occurring. However, in the 1970s, oceanographers began noting increased instances and expanses of dead zones. These occur near inhabited coastlines, where aquatic life is most concentrated.

Caribbean Sea

Caribbean Sea

The Caribbean Sea is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles starting with Cuba, to the east by the Lesser Antilles, and to the south by the northern coast of South America. The Gulf of Mexico lies to the northwest.

Gulf of Mexico

Gulf of Mexico

The Gulf of Mexico is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States; on the southwest and south by the Mexican states of Tamaulipas, Veracruz, Tabasco, Campeche, Yucatan, and Quintana Roo; and on the southeast by Cuba. The Southern U.S. states of Texas, Louisiana, Mississippi, Alabama, and Florida, which border the Gulf on the north, are often referred to as the "Third Coast" of the United States.

Lake Maracaibo

Lake Maracaibo

Lake Maracaibo is a lagoon in northwestern Venezuela, the largest lake in South America and one of the oldest on Earth, formed 36 million years ago in the Andes Mountains. The fault in the northern section has collapsed and is rich in oil and gas resources. It is Venezuela's main oil producing area and an important fishing and agricultural producing area. It is inhabited by a quarter of the country's population and is also the place with the most frequent lightning on earth. The famous Catatumbo lightning can illuminate nighttime navigation, and eutrophication caused by oil pollution is a major environmental problem facing the lake.

Source: "Atlantic Ocean", Wikipedia, Wikimedia Foundation, (2023, March 26th), https://en.wikipedia.org/wiki/Atlantic_Ocean.

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See also
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Sources

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