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86-614: Only the uppermost part of the fill of the Hatton Basin is known with certainty, based on DSDP boreholes (sites 116 & 117) and ODP borehole 982. The interpretation of the deeper parts relies on correlation with older sequences known from the Hatton Bank. The basement is thought to consist of metamorphic rocks of Paleoproterozoic age, based on sampling from the Rockall High. The oldest sedimentary rocks proven in

172-492: A World Heritage Site for their geological value, four of them are considered of "Outstanding Universal Value" based on their cultural and natural criteria: Þingvellir , Iceland; Landscape of the Pico Island Vineyard Culture , Portugal; Gough and Inaccessible Islands , United Kingdom; and Brazilian Atlantic Islands: Fernando de Noronha and Atol das Rocas Reserves, Brazil. Continental shelves in

258-506: A Navy Sonic Depth Finder to draw a continuous map across the bed of the Atlantic. This involved little guesswork because the idea of sonar is straightforward with pulses being sent from the vessel, which bounce off the ocean floor, then return to the vessel. The deep ocean floor is thought to be fairly flat with occasional deeps, abyssal plains , trenches , seamounts , basins , plateaus , canyons , and some guyots . Various shelves along

344-721: A branch of the Gulf Stream which flows northward from the Grand Banks ; and the Subpolar Front , an extension of the North Atlantic Current, a wide, vaguely defined region separating the subtropical gyre from the subpolar gyre. This system of currents transports warm water into the North Atlantic, without which temperatures in the North Atlantic and Europe would plunge dramatically. North of

430-533: A general continuous cooling since early Eocene with a significant temperature drop at the Oligocene/Eocene boundary. This surface water temperature appears to indicate that Antarctic ice sheet probable at this time already reached to the coast. Glaciers on the continent at higher altitudes, however, may have started to grow since the early Eocene. This conclusion is in consistence with other reports documented above. Atlantic The Atlantic Ocean

516-639: A total of 15 wells drilled around the Antarctic continent, including 4 wells in the Ross Sea, 5 wells on the continental margins, 2 wells in the abyssal plain and 4 wells across the SE Indian Ridge, among which the Site 270 was drilled at the highest latitude (77° 26.45′ S) Analyses of data collected from the drilling accomplish the following results: Prior to the deep sea drilling program, the ages of

602-416: A weak Intertropical Convergence Zone , South Atlantic tropical cyclones are rare. The Atlantic Ocean is underlain mostly by dense mafic oceanic crust made up of basalt and gabbro and overlain by fine clay, silt and siliceous ooze on the abyssal plain. The continental margins and continental shelf mark lower density, but greater thickness felsic continental rock that is often much older than that of

688-621: Is a complex of four water masses, two that form by deep convection in the open ocean – classical and upper Labrador sea water – and two that form from the inflow of dense water across the Greenland-Iceland-Scotland sill – Denmark Strait and Iceland-Scotland overflow water. Along its path across Earth the composition of the NADW is affected by other water masses, especially Antarctic bottom water and Mediterranean overflow water. The NADW

774-467: Is fed by a flow of warm shallow water into the northern North Atlantic which is responsible for the anomalous warm climate in Europe. Changes in the formation of NADW have been linked to global climate changes in the past. Since human-made substances were introduced into the environment, the path of the NADW can be traced throughout its course by measuring tritium and radiocarbon from nuclear weapon tests in

860-498: Is found off the eastern coast of Canada. Surface water temperatures, which vary with latitude, current systems, and season and reflect the latitudinal distribution of solar energy, range from below −2 °C (28 °F) to over 30 °C (86 °F). Maximum temperatures occur north of the equator, and minimum values are found in the polar regions. In the middle latitudes, the area of maximum temperature variations, values may vary by 7–8 °C (13–14 °F). From October to June

946-575: Is interrupted by larger transform faults at two places: the Romanche Trench near the Equator and the Gibbs fracture zone at 53°N . The MAR is a barrier for bottom water, but at these two transform faults deep water currents can pass from one side to the other. The MAR rises 2–3 km (1.2–1.9 mi) above the surrounding ocean floor and its rift valley is the divergent boundary between

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1032-854: Is intersected by two perpendicular ridges: the Azores–Gibraltar Transform Fault , the boundary between the Nubian and Eurasian plates , intersects the MAR at the Azores triple junction , on either side of the Azores microplate, near the 40°N . A much vaguer, nameless boundary, between the North American and South American plates, intersects the MAR near or just north of the Fifteen-Twenty fracture zone , approximately at 16°N . In

1118-729: Is now northern and central Brazil. The formation of the Central American Isthmus closed the Central American Seaway at the end of the Pliocene 2.8 Ma ago. The formation of the isthmus resulted in the migration and extinction of many land-living animals, known as the Great American Interchange , but the closure of the seaway resulted in a "Great American Schism" as it affected ocean currents, salinity, and temperatures in both

1204-794: Is now the Carpathian region, that were similar to the Sargasso Sea. It is possible that the population in the Sargasso Sea migrated to the Atlantic as the Tethys closed at the end of the Miocene around 17 Ma. The origin of the Sargasso fauna and flora remained enigmatic for centuries. The fossils found in the Carpathians in the mid-20th century often called the "quasi-Sargasso assemblage", finally showed that this assemblage originated in

1290-690: Is the second-largest of the world's five oceanic divisions , with an area of about 85,133,000 km (32,870,000 sq mi). It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery , it was known for separating the New World of the Americas ( North America and South America ) from the Old World of Afro-Eurasia ( Africa , Asia , and Europe ). Through its separation of Afro-Eurasia from

1376-519: Is then a major hiatus, with the next youngest preserved strata above the unconformity (known regionally as C30) being of Upper Eocene to Lower Oligocene age. The remainder of the sequence consists of Miocene to Pleistocene calcareous oozes . The basin is understood to be a result of rifting within the Hatton–Rockall plateau. The age of the rifting is poorly constrained, but is thought to be of Cretaceous age. From wide-angle seismic profiles over

1462-472: The Age of Discovery , the Atlantic was also known to English cartographers as the Great Western Ocean . The pond is a term often used by British and American speakers in reference to the northern Atlantic Ocean, as a form of meiosis , or ironic understatement. It is used mostly when referring to events or circumstances "on this side of the pond" or "on the other side of the pond" or "across

1548-564: The Carpathian Basin from where it migrated over Sicily to the central Atlantic where it evolved into modern species of the Sargasso Sea. The location of the spawning ground for European eels remained unknown for decades . In the early 19th century it was discovered that the southern Sargasso Sea is the spawning ground for both the European and American eel and that the former migrate more than 5,000 km (3,100 mi) and

1634-474: The Icelandic Low produces frequent storms. Icebergs are common from early February to the end of July across the shipping lanes near the Grand Banks of Newfoundland . The ice season is longer in the polar regions, but there is little shipping in those areas. Hurricanes are a hazard in the western parts of the North Atlantic during the summer and autumn. Due to a consistently strong wind shear and

1720-909: The Integrated Ocean Drilling Program in 2004 and the present International Ocean Discovery Program in 2013. The initial contract between the National Science Foundation (NSF) and the Regents of the University of California was signed on June 24, 1966. This contract initiated the first phase of the DSDP, which was based in Scripps Institution of Oceanography at the University of California, San Diego . Global Marine, Inc. conducted

1806-664: The Mediterranean and Red Sea . Technical and scientific reports followed during the period. The second phase of DSDP ended on August 11, 1972. The success of the Glomar Challenger was almost immediate. On one of the sites with a water depth of 1,067 m (3,501 feet), core samples revealed the existence of salt domes . Oil companies received samples after an agreement to publish their analysis. The potential of oil beneath deep ocean salt domes remains an important avenue for commercial development today. As for

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1892-684: The North American and Eurasian plates in the North Atlantic and the South American and African plates in the South Atlantic. The MAR produces basaltic volcanoes in Eyjafjallajökull , Iceland, and pillow lava on the ocean floor. The depth of water at the apex of the ridge is less than 2,700 m (1,500 fathoms ; 8,900  ft ) in most places, while the bottom of the ridge is three times as deep. The MAR

1978-616: The North Atlantic Drift is thought to have at least some influence on climate. For example, the Gulf Stream helps moderate winter temperatures along the coastline of southeastern North America, keeping it warmer in winter along the coast than inland areas. The Gulf Stream also keeps extreme temperatures from occurring on the Florida Peninsula. In the higher latitudes, the North Atlantic Drift, warms

2064-514: The North Atlantic oscillation , occurs. On average, the Atlantic is the saltiest major ocean; surface water salinity in the open ocean ranges from 33 to 37 parts per thousand (3.3–3.7%) by mass and varies with latitude and season. Evaporation, precipitation, river inflow and sea ice melting influence surface salinity values. Although the lowest salinity values are just north of the equator (because of heavy tropical rainfall), in general,

2150-555: The Scotia Sea , and other tributary water bodies. Including these marginal seas the coast line of the Atlantic measures 111,866 km (69,510 mi) compared to 135,663 km (84,297 mi) for the Pacific. Including its marginal seas, the Atlantic covers an area of 106,460,000 km (41,100,000 sq mi) or 23.5% of the global ocean and has a volume of 310,410,900 km (74,471,500 cu mi) or 23.3% of

2236-619: The Titan in Greek mythology , who supported the heavens and who later appeared as a frontispiece in medieval maps and also lent his name to modern atlases . On the other hand, to early Greek sailors and in ancient Greek mythological literature such as the Iliad and the Odyssey , this all-encompassing ocean was instead known as Oceanus , the gigantic river that encircled the world; in contrast to

2322-666: The United Kingdom . From the 16th to 19th centuries, the Atlantic Ocean was the center of both an eponymous slave trade and the Columbian exchange while occasionally hosting naval battles. Such naval battles, as well as growing trade from regional American powers like the United States and Brazil , both increased in degree during the early 20th century, and while no major military conflicts have taken place in

2408-638: The meridional overturning circulation (MOC), the northward heat transport of which is threatened by anthropogenic climate change. Large variations in the subpolar gyre on a decade-century scale, associated with the North Atlantic oscillation , are especially pronounced in Labrador Sea Water , the upper layers of the MOC. The South Atlantic is dominated by the anti-cyclonic southern subtropical gyre. The South Atlantic Central Water originates in this gyre, while Antarctic Intermediate Water originates in

2494-458: The thermocline of the subtropical gyre. The Sargasso Sea in the western North Atlantic can be defined as the area where two species of Sargassum ( S. fluitans and natans ) float, an area 4,000 km (2,500 mi) wide and encircled by the Gulf Stream , North Atlantic Drift , and North Equatorial Current . This population of seaweed probably originated from Tertiary ancestors on

2580-555: The "Initial Reports of the Deep Sea Drilling Project", which contains the results of studies of the recovered core material and the associated geophysical information from the expeditions from 1968 to 1983. These reports describe the core materials and scientific data obtained at sea and in shore-based laboratories post-cruise. These volumes were originally prepared for NSF under contract by the University of California , Scripps Institution of Oceanography . In 2007,

2666-578: The 1870s, the Challenger expedition discovered parts of what is now known as the Mid-Atlantic Ridge, or: An elevated ridge rising to an average height of about 1,900 fathoms [3,500 m; 11,400 ft] below the surface traverses the basins of the North and South Atlantic in a meridianal direction from Cape Farewell, probably its far south at least as Gough Island, following roughly

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2752-618: The 1953 definition it extends south to Antarctica, while in later maps it is bounded at the 60° parallel by the Southern Ocean. The Atlantic has irregular coasts indented by numerous bays, gulfs and seas. These include the Baltic Sea , Black Sea , Caribbean Sea , Davis Strait , Denmark Strait , part of the Drake Passage , Gulf of Mexico , Labrador Sea , Mediterranean Sea , North Sea , Norwegian Sea , almost all of

2838-485: The 1960s and CFCs . The clockwise warm-water North Atlantic Gyre occupies the northern Atlantic, and the counter-clockwise warm-water South Atlantic Gyre appears in the southern Atlantic. In the North Atlantic, surface circulation is dominated by three inter-connected currents: the Gulf Stream which flows north-east from the North American coast at Cape Hatteras ; the North Atlantic Current ,

2924-578: The Americas, the Atlantic Ocean has played a central role in the development of human society, globalization, and the histories of many nations. While the Norse were the first known humans to cross the Atlantic, it was the expedition of Christopher Columbus in 1492 that proved to be the most consequential. Columbus' expedition ushered in an age of exploration and colonization of the Americas by European powers , most notably Portugal , Spain , France , and

3010-537: The Atlantic are wide off Newfoundland, southernmost South America, and northeastern Europe. In the western Atlantic carbonate platforms dominate large areas, for example, the Blake Plateau and Bermuda Rise . The Atlantic is surrounded by passive margins except at a few locations where active margins form deep trenches : the Puerto Rico Trench (8,376 m or 27,480 ft maximum depth) in

3096-625: The Atlantic include the Challenger expedition and the German Meteor expedition ; as of 2001 , Columbia University 's Lamont–Doherty Earth Observatory and the United States Navy Hydrographic Office conduct research on the ocean. The MAR divides the Atlantic longitudinally into two halves, in each of which a series of basins are delimited by secondary, transverse ridges. The MAR reaches above 2,000 m (6,600 ft) along most of its length, but

3182-403: The Atlantic north of the equator. The coldest zones are in high latitudes, with the coldest regions corresponding to the areas covered by sea ice. Ocean currents influence the climate by transporting warm and cold waters to other regions. The winds that are cooled or warmed when blowing over these currents influence adjacent land areas. The Gulf Stream and its northern extension towards Europe,

3268-589: The Atlantic recently, the ocean remains a core component of trade around the world. The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Europe and Africa to the east, and the Americas to the west. As one component of the interconnected World Ocean , it is connected in the north to the Arctic Ocean , to the Pacific Ocean in the southwest, the Indian Ocean in

3354-469: The Atlantic sea ' , etym . ' Sea of Atlas ' ) and in The Histories of Herodotus around 450 BC (Hdt. 1.202.4): Atlantis thalassa (Ancient Greek: Ἀτλαντὶς θάλασσα , ' Sea of Atlas ' or ' the Atlantic sea ' ) where the name refers to "the sea beyond the pillars of Heracles " which is said to be part of the sea that surrounds all land. In these uses, the name refers to Atlas ,

3440-633: The Bahamas, while coarse river outwash sands and silt are common in shallow shelf areas like the Georges Bank . Coarse sand, boulders, and rocks were transported into some areas, such as off the coast of Nova Scotia or the Gulf of Maine during the Pleistocene ice ages. The break-up of Pangaea began in the central Atlantic, between North America and Northwest Africa, where rift basins opened during

3526-516: The European shores of the former Tethys Ocean and has, if so, maintained itself by vegetative growth , floating in the ocean for millions of years. Other species endemic to the Sargasso Sea include the sargassum fish , a predator with algae-like appendages which hovers motionless among the Sargassum . Fossils of similar fishes have been found in fossil bays of the former Tethys Ocean, in what

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3612-477: The Glomar Challenger achieved the following accomplishments: The ship retrieved core samples in 9-meter-long (30 ft) cores with a diameter of 6.5 cm (2.5 inches). These cores are currently stored at three repositories in the US, Germany, and Japan. One half of each core is called the archive half and is preserved for future use. The working half of each core is used to provide samples for ongoing scientific research. The scientific results were published as

3698-405: The Late Triassic and Early Jurassic. This period also saw the first stages of the uplift of the Atlas Mountains. The exact timing is controversial with estimates ranging from 200 to 170 Ma. The opening of the Atlantic Ocean coincided with the initial break-up of the supercontinent Pangaea , both of which were initiated by the eruption of the Central Atlantic Magmatic Province (CAMP), one of

3784-468: The North Atlantic Gyre, the cyclonic North Atlantic Subpolar Gyre plays a key role in climate variability. It is governed by ocean currents from marginal seas and regional topography, rather than being steered by wind, both in the deep ocean and at sea level. The subpolar gyre forms an important part of the global thermohaline circulation . Its eastern portion includes eddying branches of the North Atlantic Current which transport warm, saline waters from

3870-456: The Oligocene. In addition, drilling onshore around the Ross Sea and on the Antarctic Peninsular also confirms that Antarctic ice sheet already existed at least since the Oligocene. The occurrence of ice-rafted debris in marine sediments is an indication of icebergs presence. Hence the earliest occurrence in the high latitudes could possibly reveal the inception of sea-level glaciations. It should be pointed out that there are factors influencing

3956-409: The Ross shelf began to sink below sea-level about 25 Mya in the Oligocene. This suggests that Antarctic glaciers already advanced to the Ross Sea shelf. This age is consistent with the dating of the shallow unconformity seen on the seismic profiles. The unconformity was attributed to the glacier erosion when advancing to the coastal area. Development of the Circum Antarctic Current was also initiated in

4042-437: The South Atlantic, and the "Atmospheric Bridge", which evaporates subtropical Atlantic waters and exports it to the Pacific. The Atlantic Ocean consists of four major, upper water masses with distinct temperature and salinity. The Atlantic subarctic upper water in the northernmost North Atlantic is the source for subarctic intermediate water and North Atlantic intermediate water. North Atlantic central water can be divided into

4128-438: The area are Albian (uppermost Lower Cretaceous ) mudstones and sandstones, encountered in two British Geological Survey boreholes drilled on the Hatton Bank. By comparison with neighbouring basins both Paleozoic and Mesozoic sequences are expected to be present in the Hatton Basin. The proven Cenozoic sequence starts with Paleocene lavas, part of the North Atlantic Igneous Province , overlain by Eocene claystones . There

4214-412: The atmosphere over the oceans, keeping the British Isles and northwestern Europe mild and cloudy, and not severely cold in winter, like other locations at the same high latitude. The cold water currents contribute to heavy fog off the coast of eastern Canada (the Grand Banks of Newfoundland area) and Africa's northwestern coast. In general, winds transport moisture and air over land areas. Every winter,

4300-465: The basin and the adjacent highs, a stretching factor of about 2 has been estimated. 57°N 19°W  /  57°N 19°W  / 57; -19 Deep Sea Drilling Project The Deep Sea Drilling Project ( DSDP ) was an ocean drilling project operated from 1968 to 1983. The program was a success, as evidenced by the data and publications that have resulted from it. The data are now hosted by Texas A&M University , although

4386-432: The coast of New York . This re-entry was accomplished with the use of sonar scanning equipment and a re-entry cone that had a diameter of 5 m (16 feet) and height of 4.5 m (14 feet). One major technological advance was the extended use of the holes after drilling. Geophysical and geochemical measurements were made during and after drilling, and occasionally long-term seismic monitoring devices were installed in

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4472-427: The continent This interpretation of Antarctic glaciation history based on marine sediments was subsequently supported by the onshore study of the Antarctic Peninsular and by the coring results around McMurdo Ice Shelf. Micropaleontologic data from deep sea sediments around the Antarctic continental margin indicate that since at least the late Oligocene-early Miocene, surface waters were relatively cool. With

4558-495: The continued cooling trend, the cold water mass gradually expanded northward until early Pliocene during which an intensified cooling episode resulted in a temperature minimum as evidenced by the northward shift of the silica/carbonate facies boundary. This deduction is similar to the conclusion based on ice-rated debris studies. Surface temperatures inferred from the oxygen and carbon isotope analyses of both benthonic and planktonic foraminifera in high-latitude marine sediments show

4644-418: The distribution of ice-rafted debris, such as ocean currents, and sea water near surface temperatures. Hence the earliest occurrence should be considered as the minimum age of ice rafting at sample locations. Investigations of ice-rafted debris reasonably conclude that the Antarctic ice sheet was initiated at least 25 Mya and cumulated at about 4.5 Mya, as evidenced by ice-rafted debris reaching farthest away from

4730-478: The drilling operations. The Levingston Shipbuilding Company laid the keel of the Glomar Challenger on October 18, 1967, in Orange, Texas . It sailed down the Sabine River to the Gulf of Mexico , and after a period of testing, DSDP accepted the ship on August 11, 1968. Through contracts with Joint Oceanographic Institutions (JOI), NSF supported the scientific advisory structure for the project and funded pre-drilling geophysical site surveys. Scientific planning

4816-431: The east, the boundaries of the ocean proper are Europe: the Strait of Gibraltar (where it connects with the Mediterranean Sea  – one of its marginal seas  – and, in turn, the Black Sea , both of which also touch upon Asia) and Africa. In the southeast, the Atlantic merges into the Indian Ocean. The 20° East meridian , running south from Cape Agulhas to Antarctica defines its border. In

4902-544: The eastern and western North Atlantic central water since the western part is strongly affected by the Gulf Stream and therefore the upper layer is closer to underlying fresher subpolar intermediate water. The eastern water is saltier because of its proximity to Mediterranean water. North Atlantic central water flows into South Atlantic central water at 15°N . There are five intermediate waters: four low-salinity waters formed at subpolar latitudes and one high-salinity formed through evaporation. Arctic intermediate water flows from

4988-400: The enclosed seas well known to the Greeks: the Mediterranean and the Black Sea. In contrast, the term "Atlantic" originally referred specifically to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the West African coast. The term " Aethiopian Ocean ", derived from Ancient Ethiopia , was applied to the southern Atlantic as late as the mid-19th century. During

5074-403: The holes. This extended understanding of the dynamic processes involved in plate tectonics . Another technological advance involved the introduction of the hydraulic piston corer (HPC ) in 1979, which permitted the recovery of virtually undisturbed cores of sediment. This greatly enhanced the ability of scientists to study ancient ocean environments. From August 11, 1968, to November 11, 1983,

5160-459: The last time with DSDP in November 1983. Parts of the ship, such as its dynamic positioning system, engine telegraph, and thruster console, are stored at the Smithsonian Institution in Washington, D.C. With the advent of larger and more advanced drilling ships, the JOIDES Resolution replaced the Glomar Challenger in January 1985. The new program, called the Ocean Drilling Program (ODP), continued exploration from 1985 to 2003, at which point it

5246-454: The latter 2,000 km (1,200 mi). Ocean currents such as the Gulf Stream transport eel larvae from the Sargasso Sea to foraging areas in North America, Europe, and northern Africa. Recent but disputed research suggests that eels possibly use Earth's magnetic field to navigate through the ocean both as larvae and as adults. The climate is influenced by the temperatures of the surface waters and water currents as well as winds. Because of

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5332-474: The limits of the oceans and seas in 1953, but some of these definitions have been revised since then and some are not recognized by various authorities, institutions, and countries, for example the CIA World Factbook . Correspondingly, the extent and number of oceans and seas vary. The Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait , Greenland Sea , Norwegian Sea and Barents Sea . To

5418-429: The lowest values are in the high latitudes and along coasts where large rivers enter. Maximum salinity values occur at about 25° north and south , in subtropical regions with low rainfall and high evaporation. The high surface salinity in the Atlantic, on which the Atlantic thermohaline circulation is dependent, is maintained by two processes: the Agulhas Leakage/Rings , which brings salty Indian Ocean waters into

5504-454: The margins of the continents constitute about 11% of the bottom topography with few deep channels cut across the continental rise. The mean depth between 60°N and 60°S is 3,730 m (12,240 ft), or close to the average for the global ocean, with a modal depth between 4,000 and 5,000 m (13,000 and 16,000 ft). In the South Atlantic the Walvis Ridge and Rio Grande Rise form barriers to ocean currents. The Laurentian Abyss

5590-407: The maximum depth, the Milwaukee Deep in the Puerto Rico Trench , is 8,376 m (27,480 ft). Top large seas: The bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge (MAR). It runs from 87°N or 300 km (190 mi) south of the North Pole to the subantarctic Bouvet Island at 54°S . Expeditions to explore the bathymertry of

5676-510: The most extensive and voluminous large igneous provinces in Earth's history associated with the Triassic–Jurassic extinction event , one of Earth's major extinction events . Theoliitic dikes , sills , and lava flows from the CAMP eruption at 200 Ma have been found in West Africa, eastern North America, and northern South America. The extent of the volcanism has been estimated to 4.5 × 10  km (1.7 × 10  sq mi) of which 2.5 × 10  km (9.7 × 10  sq mi) covered what

5762-502: The north to become the source for North Atlantic deep water, south of the Greenland-Scotland sill. These two intermediate waters have different salinity in the western and eastern basins. The wide range of salinities in the North Atlantic is caused by the asymmetry of the northern subtropical gyre and a large number of contributions from a wide range of sources: Labrador Sea, Norwegian-Greenland Sea, Mediterranean, and South Atlantic Intermediate Water. The North Atlantic deep water (NADW)

5848-402: The ocean bottom could have been as great as 1,299 m (4,262 feet). To replace the bit, the drill string must be raised, a new bit attached, and the string remade down to the bottom. However, the crew had to thread this string back into the same drill hole. The technique for this formidable task was accomplished on June 14, 1970, in the Atlantic Ocean in 3,000 m (10,000 feet) of water off

5934-444: The ocean floor is probably no older than 200 million years. This is in comparison with the 4.5 billion-year age of the Earth. The International Phase of Ocean Drilling (IPOD) began in 1975 with the Federal Republic of Germany , Japan , the United Kingdom , the Soviet Union , and France joining the United States in field work aboard the Glomar Challenger and in post-cruise scientific research. The Glomar Challenger docked for

6020-425: The ocean's great capacity to store and release heat, maritime climates are more moderate and have less extreme seasonal variations than inland climates. Precipitation can be approximated from coastal weather data and air temperature from water temperatures. The oceans are the major source of atmospheric moisture that is obtained through evaporation. Climatic zones vary with latitude; the warmest zones stretch across

6106-485: The oceanic basalt were estimated based on magnetic lineations generated at the spreading center as the sea floor pulled apart. Sediments immediately overlying the basalt should have ages similar to the age of magnetic stripes. This is confirmed by the micropaleontologic analyses of the basal sediments sampled above the penetrated basalts. These analyses furthermore substantiate that Australia was separated from Antarctic 85 Mya [million years ago] Based on paleo-soil study,

6192-565: The outlines of the coasts of the Old and the New Worlds. The remainder of the ridge was discovered in the 1920s by the German Meteor expedition using echo-sounding equipment. The exploration of the MAR in the 1950s led to the general acceptance of seafloor spreading and plate tectonics . Most of the MAR runs under water but where it reaches the surfaces it has produced volcanic islands. While nine of these have collectively been nominated

6278-595: The pond", rather than to discuss the ocean itself. The term dates to 1640, first appearing in print in a pamphlet released during the reign of Charles I , and reproduced in 1869 in Nehemiah Wallington 's Historical Notices of Events Occurring Chiefly in The Reign of Charles I , where "great Pond" is used in reference to the Atlantic Ocean by Francis Windebank , Charles I's Secretary of State . The International Hydrographic Organization (IHO) defined

6364-493: The printed books were scanned and prepared for electronic presentation by the Texas A&;M University College of Geosciences. DSDP completed four drilling programs; Legs 28, 29, 35 and 36 around Antarctica during four Austral summers, 1972–73, 1973–74, 1974–75 and 1975–76. These programs were focused on two main objectives: Cenozoic global paleoclimatic changes and plate tectonic movements around Antarctica. There were

6450-503: The program was coordinated by the Scripps Institution of Oceanography at the University of California, San Diego . DSDP provided crucial data to support the seafloor spreading hypothesis and helped to prove the theory of plate tectonics . DSDP was the first of three international scientific ocean drilling programs that have operated over more than 40 years. It was followed by the Ocean Drilling Program (ODP) in 1985,

6536-409: The proposal of a single, ancient land mass, which is called Pangaea . The samples gave further evidence to support the plate tectonics theory , which at the time attempted to explain the formation of mountain ranges, earthquakes, and oceanic trenches . Another discovery was how youthful the ocean floor is in comparison to Earth's geologic history. After analysis of samples, scientists concluded that

6622-406: The purpose of the scientific exploration, one of the most important discoveries was made when the crew drilled 17 holes at 10 different locations along an oceanic ridge between South America and Africa . The retrieved core samples provided strong proof for continental drift and seafloor renewal at rift zones . This confirmation of Alfred Wegener 's theory of continental drift strengthened

6708-438: The seafloor. The oldest oceanic crust in the Atlantic is up to 145 million years and is situated off the west coast of Africa and the east coast of North America, or on either side of the South Atlantic. In many places, the continental shelf and continental slope are covered in thick sedimentary layers. For instance, on the North American side of the ocean, large carbonate deposits formed in warm shallow waters such as Florida and

6794-536: The southeast, and the Southern Ocean in the south. Other definitions describe the Atlantic as extending southward to Antarctica . The Atlantic Ocean is divided in two parts, the northern and southern Atlantic, by the Equator . The oldest known mentions of an "Atlantic" sea come from Stesichorus around mid-sixth century BC (Sch. A. R. 1. 211): Atlantikôi pelágei (Ancient Greek: Ἀτλαντικῷ πελάγει , '

6880-551: The subtropics to the northeastern Atlantic. There this water is cooled during winter and forms return currents that merge along the eastern continental slope of Greenland where they form an intense (40–50  Sv ) current which flows around the continental margins of the Labrador Sea . A third of this water becomes part of the deep portion of the North Atlantic Deep Water (NADW). The NADW, in turn, feeds

6966-421: The surface is usually covered with sea ice in the Labrador Sea , Denmark Strait , and Baltic Sea. The Coriolis effect circulates North Atlantic water in a clockwise direction, whereas South Atlantic water circulates counter-clockwise. The south tides in the Atlantic Ocean are semi-diurnal; that is, two high tides occur every 24 lunar hours. In latitudes above 40° North some east–west oscillation, known as

7052-480: The total volume of the Earth's oceans. Excluding its marginal seas, the Atlantic covers 81,760,000 km (31,570,000 sq mi) and has a volume of 305,811,900 km (73,368,200 cu mi). The North Atlantic covers 41,490,000 km (16,020,000 sq mi) (11.5%) and the South Atlantic 40,270,000 km (15,550,000 sq mi) (11.1%). The average depth is 3,646 m (11,962 ft) and

7138-636: The upper layers of the circumpolar region, near the Drake Passage and the Falkland Islands. Both these currents receive some contribution from the Indian Ocean. On the African east coast, the small cyclonic Angola Gyre lies embedded in the large subtropical gyre. The southern subtropical gyre is partly masked by a wind-induced Ekman layer . The residence time of the gyre is 4.4–8.5 years. North Atlantic Deep Water flows southward below

7224-424: The western Atlantic and South Sandwich Trench (8,264 m or 27,113 ft) in the South Atlantic. There are numerous submarine canyons off northeastern North America, western Europe, and northwestern Africa. Some of these canyons extend along the continental rises and farther into the abyssal plains as deep-sea channels. In 1922, a historic moment in cartography and oceanography occurred. The USS Stewart used

7310-548: Was conducted under the auspices of the Joint Oceanographic Institutions for Deep Earth Sampling (JOIDES). The JOIDES advisory group consisted of 250 distinguished scientists from academic institutions, government agencies, and private industry from all over the world. Over the next 30 months, the second phase consisted of drilling and coring in the Atlantic , Pacific , and Indian Ocean as well as

7396-485: Was replaced by the Integrated Ocean Drilling Program (IODP). Although itself a remarkable engineering accomplishment, the Glomar Challenger saw many advances in deep-ocean drilling. One problem solved involved the replacement of worn drill bits. A length of pipe suspended from the ship down to the bottom of the sea might have been as long as 6,243 m (20,483 feet). The maximum depth penetrated through

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