1.
Oceanic plateau
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An oceanic plateau is a large, relatively flat submarine region that rises well above the level of the ambient seabed. While many oceanic plateaus are composed of continental crust, and often form a step interrupting the continental slope and these were formed by the equivalent of continental flood basalts such as the Deccan Traps in India and the Snake River Plain in the Pacific Northwest of the United States. There are over 180 oceanic plateaus covering an area of 18,486,600 km2, the South Pacific region around Australia and New Zealand contains the greatest number of oceanic plateaus. Density differences in crustal material largely arise from different ratios of various elements, continental crust has the highest amount of silicon. Oceanic crust has an amount of silicon. Igneous oceanic plateaus have an intermediate between continental and oceanic crust, although they are more mafic than felsic
2.
Large igneous province
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The source of many or all LIPs is variously attributed to mantle plumes or to processes associated with plate tectonics. Types of LIPs can include large volcanic provinces, created through flood basalt, rampino and Stothers cite eleven distinct flood-basalt episodes - occurring in the past 250 million years - which created volcanic provinces and plateaus and coincided with mass extinctions. However, more flood basalts have been recognized, such as the large Ontong Java Plateau, mafic, basalt sea floors and other geological products of normal plate tectonics were not included in the definition. The definition of LIP has been expanded and refined, and is still a work in progress, LIP is now frequently also used to describe voluminous areas of, not just mafic, but all types of igneous rocks. Sub-categorization of LIPs into large volcanic provinces and large plutonic provinces, Large igneous provinces are created during short-lived igneous events resulting in relatively rapid and high-volume accumulations of volcanic and intrusive igneous rock. These events warrant study because, The study of LIPs has economic implications, some workers associate them with trapped hydrocarbons. They are associated with economic concentrations of copper–nickel and iron and they are also associated with formation of major mineral provinces including Platinum-Group Element Deposits, and in the Silicic LIPs, silver and gold deposits. Titanium and vanadium deposits are found in association with LIPs. Future LIP events may pose a hazard to human civilization, LIPs in the geological record have marked major changes in the hydrosphere and atmosphere, leading to major climate shifts and maybe mass extinctions of species. Plate tectonic theory explains topography using interactions between the plates, as influenced by viscous stresses created by flow within the underlying mantle. Since the mantle is extremely viscous, the flow rate varies in pulses which are reflected in the lithosphere by small amplitude. Understanding how the interaction between mantle flow and lithosphere elevation influences formation of LIPs is important to gaining insights into past mantle dynamics, LIPs have played a major role in continental breakup, continental formation, new crustal additions from the upper mantle, and supercontinent cycles. Earth has a shell made of a number of discrete. The mantles flow is driven by the descent of cold tectonic plates during subduction, the surface of the Earth reflects stretching, thickening and bending of the tectonic plates as they interact. In this model, tectonic plates diverge at mid-ocean ridges, where hot mantle rock flows upward to fill the space, plate-tectonic processes account for the vast majority of Earths volcanism. Beyond the effects of convectively driven motion, deep processes have other influences on the surface topography, the convective circulation drives up-wellings and down-wellings in Earths mantle that are reflected in local surface levels. Hot mantle materials rising up in a plume can spread out radially beneath the tectonic plate causing regions of uplift and these ascending plumes play an important role in LIP formation. When created, LIPs often have an extent of a few million km²
3.
Indian Ocean
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The Indian Ocean is the third largest of the worlds oceanic divisions, covering 70,560,000 km2. It is bounded by Asia on the north, on the west by Africa, on the east by Australia, the Indian Ocean is known as Ratnākara, the mine of gems in ancient Sanskrit literature, and as Hind Mahāsāgar, in Hindi. The northernmost extent of the Indian Ocean is approximately 30° north in the Persian Gulf, the oceans continental shelves are narrow, averaging 200 kilometres in width. An exception is found off Australias western coast, where the width exceeds 1,000 kilometres. The average depth of the ocean is 3,890 m and its deepest point is Diamantina Deep in Diamantina Trench, at 8,047 m deep, Sunda Trench has a depth of 7, 258–7,725 m. North of 50° south latitude, 86% of the basin is covered by pelagic sediments. The remaining 14% is layered with terrigenous sediments, glacial outwash dominates the extreme southern latitudes. The major choke points include Bab el Mandeb, Strait of Hormuz, the Lombok Strait, the Strait of Malacca, the Indian Ocean is artificially connected to the Mediterranean Sea through the Suez Canal, which is accessible via the Red Sea. All of the Indian Ocean is in the Eastern Hemisphere and the centre of the Eastern Hemisphere is in this ocean, marginal seas, gulfs, bays and straits of the Indian Ocean include, The climate north of the equator is affected by a monsoon climate. Strong north-east winds blow from October until April, from May until October south, in the Arabian Sea the violent Monsoon brings rain to the Indian subcontinent. In the southern hemisphere, the winds are milder. When the monsoon winds change, cyclones sometimes strike the shores of the Arabian Sea, the Indian Ocean is the warmest ocean in the world. Long-term ocean temperature records show a rapid, continuous warming in the Indian Ocean, Indian Ocean warming is the largest among the tropical oceans, and about 3 times faster than the warming observed in the Pacific. Research indicates that human induced greenhouse warming, and changes in the frequency, among the few large rivers flowing into the Indian Ocean are the Zambezi, Shatt al-Arab, Indus, Godavari, Krishna, Narmada, Ganges, Brahmaputra, Jubba and Irrawaddy River. The oceans currents are controlled by the monsoon. Two large gyres, one in the northern hemisphere flowing clockwise and one south of the equator moving anticlockwise, during the winter monsoon, however, currents in the north are reversed. Deep water circulation is controlled primarily by inflows from the Atlantic Ocean, the Red Sea, north of 20° south latitude the minimum surface temperature is 22 °C, exceeding 28 °C to the east. Southward of 40° south latitude, temperatures drop quickly, surface water salinity ranges from 32 to 37 parts per 1000, the highest occurring in the Arabian Sea and in a belt between southern Africa and south-western Australia
4.
Submerged continent
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A submerged continent is a continental mass, extensive in size, but mainly undersea. The terminology is used by some paleogeologists and geographers in reference to land masses. The two main examples in class are the Kerguelen Plateau and Zealandia. Submerged continents have been sought and speculated about in regard to a possible lost continent underwater in the Atlantic Ocean, there was also a search in the 1930s for Lemuria, believed to have possibly been a submerged continent between the Indian and African coasts. Continental fragment Life timeline Mythical continents Nature timeline
5.
Australia
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Australia, officially the Commonwealth of Australia, is a country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands. It is the worlds sixth-largest country by total area, the neighbouring countries are Papua New Guinea, Indonesia and East Timor to the north, the Solomon Islands and Vanuatu to the north-east, and New Zealand to the south-east. Australias capital is Canberra, and its largest urban area is Sydney, for about 50,000 years before the first British settlement in the late 18th century, Australia was inhabited by indigenous Australians, who spoke languages classifiable into roughly 250 groups. The population grew steadily in subsequent decades, and by the 1850s most of the continent had been explored, on 1 January 1901, the six colonies federated, forming the Commonwealth of Australia. Australia has since maintained a liberal democratic political system that functions as a federal parliamentary constitutional monarchy comprising six states. The population of 24 million is highly urbanised and heavily concentrated on the eastern seaboard, Australia has the worlds 13th-largest economy and ninth-highest per capita income. With the second-highest human development index globally, the country highly in quality of life, health, education, economic freedom. The name Australia is derived from the Latin Terra Australis a name used for putative lands in the southern hemisphere since ancient times, the Dutch adjectival form Australische was used in a Dutch book in Batavia in 1638, to refer to the newly discovered lands to the south. On 12 December 1817, Macquarie recommended to the Colonial Office that it be formally adopted, in 1824, the Admiralty agreed that the continent should be known officially as Australia. The first official published use of the term Australia came with the 1830 publication of The Australia Directory and these first inhabitants may have been ancestors of modern Indigenous Australians. The Torres Strait Islanders, ethnically Melanesian, were originally horticulturists, the northern coasts and waters of Australia were visited sporadically by fishermen from Maritime Southeast Asia. The first recorded European sighting of the Australian mainland, and the first recorded European landfall on the Australian continent, are attributed to the Dutch. The first ship and crew to chart the Australian coast and meet with Aboriginal people was the Duyfken captained by Dutch navigator, Willem Janszoon. He sighted the coast of Cape York Peninsula in early 1606, the Dutch charted the whole of the western and northern coastlines and named the island continent New Holland during the 17th century, but made no attempt at settlement. William Dampier, an English explorer and privateer, landed on the north-west coast of New Holland in 1688, in 1770, James Cook sailed along and mapped the east coast, which he named New South Wales and claimed for Great Britain. The first settlement led to the foundation of Sydney, and the exploration, a British settlement was established in Van Diemens Land, now known as Tasmania, in 1803, and it became a separate colony in 1825. The United Kingdom formally claimed the part of Western Australia in 1828. Separate colonies were carved from parts of New South Wales, South Australia in 1836, Victoria in 1851, the Northern Territory was founded in 1911 when it was excised from South Australia
6.
Japan
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Japan is a sovereign island nation in Eastern Asia. Located in the Pacific Ocean, it lies off the eastern coast of the Asia Mainland and stretches from the Sea of Okhotsk in the north to the East China Sea, the kanji that make up Japans name mean sun origin. 日 can be read as ni and means sun while 本 can be read as hon, or pon, Japan is often referred to by the famous epithet Land of the Rising Sun in reference to its Japanese name. Japan is an archipelago consisting of about 6,852 islands. The four largest are Honshu, Hokkaido, Kyushu and Shikoku, the country is divided into 47 prefectures in eight regions. Hokkaido being the northernmost prefecture and Okinawa being the southernmost one, the population of 127 million is the worlds tenth largest. Japanese people make up 98. 5% of Japans total population, approximately 9.1 million people live in the city of Tokyo, the capital of Japan. Archaeological research indicates that Japan was inhabited as early as the Upper Paleolithic period, the first written mention of Japan is in Chinese history texts from the 1st century AD. Influence from other regions, mainly China, followed by periods of isolation, from the 12th century until 1868, Japan was ruled by successive feudal military shoguns who ruled in the name of the Emperor. Japan entered into a period of isolation in the early 17th century. The Second Sino-Japanese War of 1937 expanded into part of World War II in 1941, which came to an end in 1945 following the bombings of Hiroshima and Nagasaki. Japan is a member of the UN, the OECD, the G7, the G8, the country has the worlds third-largest economy by nominal GDP and the worlds fourth-largest economy by purchasing power parity. It is also the worlds fourth-largest exporter and fourth-largest importer, although Japan has officially renounced its right to declare war, it maintains a modern military with the worlds eighth-largest military budget, used for self-defense and peacekeeping roles. Japan is a country with a very high standard of living. Its population enjoys the highest life expectancy and the third lowest infant mortality rate in the world, in ancient China, Japan was called Wo 倭. It was mentioned in the third century Chinese historical text Records of the Three Kingdoms in the section for the Wei kingdom, Wa became disliked because it has the connotation of the character 矮, meaning dwarf. The 倭 kanji has been replaced with the homophone Wa, meaning harmony, the Japanese word for Japan is 日本, which is pronounced Nippon or Nihon and literally means the origin of the sun. The earliest record of the name Nihon appears in the Chinese historical records of the Tang dynasty, at the start of the seventh century, a delegation from Japan introduced their country as Nihon
7.
Plateau
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Plateaus can be formed by a number of processes, including upwelling of volcanic magma, extrusion of lava, and erosion by water and glaciers. Magma rises from the mantle, causing the ground to swell upward, in way, large, flat areas of rock are uplifted. Plateaus can also be built up by lava spreading outward from cracks, plateaus can also be formed by the erosional processes of glaciers on mountain ranges, leaving them sitting between the mountain ranges. Water can also erode mountains and other landforms down into plateaus, volcanic plateaus are produced by volcanic activity. The Columbia Plateau in the northwestern United States is an example, dissected plateaus are highly eroded plateaus cut by rivers and broken by deep narrow valleys. Plateaus are classified according to their surrounding environment, intermontane plateaus are the highest in the world, bordered by mountains. The Tibetan Plateau is one such plateau, Piedmont plateaus are bordered on one side by mountains and on the other by a plain or a sea. The Piedmont Plateau of the Eastern United States between the Appalachian Mountains and the Atlantic Coastal Plain is an example, continental plateaus are bordered on all sides by plains or oceans, forming away from the mountains. The Tibetan plateau covers approximately 2,500,000 km2, the plateau is sufficiently high enough to reverse the Hadley cell convection cycles and to drive the monsoons of India towards the south. The second-highest plateau is the Deosai Plateau of the Deosai National Park at an elevation of 4,114 m. It is located in the Astore and Skardu districts of Gilgit-Baltistan, Deosai means the land of giants. The park protects an area of 3,000 km2 and it is known for its rich flora and fauna of the Karakoram-West Tibetan Plateau alpine steppe ecoregion. In spring it is covered by sweeps of wildflowers and a variety of butterflies. The highest point in Deosai is Deosai Lake, or Sheosar Lake from the Shina language meaning Blind lake near the Chilim Valley. The lake lies at an elevation of 4,142 m, one of the highest lakes in the world, and is 2.3 km long,1.8 km wide, and 40 m deep on average. Some other major plateaus in Asia are, Armenian Highlands, Iranian plateau, Anatolian Plateau, Mongolian Plateau, and the Deccan Plateau. This polar ice cap is so massive that the echolocation sound measurements of ice thickness have shown that parts of the Antarctic dry land surface have been pressed below sea level. Thus, if that same ice cap were removed, the large areas of the frozen white continent would be flooded by the surrounding Antarctic Ocean or Southern Ocean
8.
Gondwana
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In paleogeography, Gondwana, also Gondwanaland, is the name given to an ancient supercontinent. It is believed to have sutured about 600 to 530 million years ago, Gondwana formed prior to Pangaea, and later became part of it. Around 335 to 250 million years ago Gondwana and Laurasia joined together to form the supercontinent Pangaea, Gondwana then separated from Laurasia in the breakup of Pangaea, drifting farther south after the split. Gondwana itself then also broke apart, the continent of Gondwana was named by Austrian scientist Eduard Suess, after the Gondwana region of central northern India which is derived from Sanskrit for forest of the Gonds. The name had previously used in a geological context, first by H. B. From which the Gondwana sedimentary sequences are also described, for example, the plant family Proteaceae, known only from southern South America, South Africa, Australia, and New Zealand, is considered to have a Gondwanan distribution. This pattern is considered to indicate an archaic, or relict. The assembly of Gondwana was a protracted process, several orogenies led to its final amalgamation 550 to 500 million years ago at the end of the Ediacaran, and into the Cambrian. These include the Brasiliano Orogeny, the East African Orogeny, the Malagasy Orogeny, the final stages of Gondwanan assembly overlapped with the opening of the Iapetus Ocean between Laurentia and western Gondwana. During this interval, the Cambrian explosion occurred and this is the Famatinian block and it formerly continued the line of the Appalachians southwards. One of the sites of Gondwanan amalgamation was the East African Orogeny. The East African Orogeny at about 650–630 Mya affected a part of Arabia, north-eastern Africa, East Africa. Collins and Windley propose that in this orogeny, Azania collided with the Congo–Tanzania–Bangweulu Block, the later Malagasy orogeny at about 550–515 Mya affected Madagascar, eastern East Africa and southern India. In it, Neoproterozoic India collided with the already combined Azania and Congo–Tanzania–Bangweulu Block, at the same time, in the Kunga Orogeny Neoproterozoic India collided with the Australia/Mawson continent. Other large continental masses, including the core cratons of North America, Europe, when Pangaea broke up, two large masses, Gondwana and Laurasia, were formed. During the late Paleozoic, Gondwana extended from a point at or near the South Pole to near the Equator, across much of Gondwana, the climate was mild. During the Mesozoic, the world was on average warmer than it is today. Gondwana was then host to a variety of flora and fauna for many millions of years
9.
Sea level
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Mean sea level is an average level of the surface of one or more of Earths oceans from which heights such as elevations may be measured. A common and relatively straightforward mean sea-level standard is the midpoint between a low and mean high tide at a particular location. Sea levels can be affected by factors and are known to have varied greatly over geological time scales. The careful measurement of variations in MSL can offer insights into ongoing climate change, the term above sea level generally refers to above mean sea level. Precise determination of a sea level is a difficult problem because of the many factors that affect sea level. Sea level varies quite a lot on several scales of time and this is because the sea is in constant motion, affected by the tides, wind, atmospheric pressure, local gravitational differences, temperature, salinity and so forth. The easiest way this may be calculated is by selecting a location and calculating the mean sea level at that point, for example, a period of 19 years of hourly level observations may be averaged and used to determine the mean sea level at some measurement point. One measures the values of MSL in respect to the land, hence a change in MSL can result from a real change in sea level, or from a change in the height of the land on which the tide gauge operates. In the UK, the Ordnance Datum is the sea level measured at Newlyn in Cornwall between 1915 and 1921. Prior to 1921, the datum was MSL at the Victoria Dock, in Hong Kong, mPD is a surveying term meaning metres above Principal Datum and refers to height of 1. 230m below the average sea level. In France, the Marégraphe in Marseilles measures continuously the sea level since 1883 and it is used for a part of continental Europe and main part of Africa as official sea level. Elsewhere in Europe vertical elevation references are made to the Amsterdam Peil elevation, satellite altimeters have been making precise measurements of sea level since the launch of TOPEX/Poseidon in 1992. A joint mission of NASA and CNES, TOPEX/Poseidon was followed by Jason-1 in 2001, height above mean sea level is the elevation or altitude of an object, relative to the average sea level datum. It is also used in aviation, where some heights are recorded and reported with respect to sea level, and in the atmospheric sciences. An alternative is to base height measurements on an ellipsoid of the entire Earth, in aviation, the ellipsoid known as World Geodetic System 84 is increasingly used to define heights, however, differences up to 100 metres exist between this ellipsoid height and mean tidal height. The alternative is to use a vertical datum such as NAVD88. When referring to geographic features such as mountains on a topographic map, the elevation of a mountain denotes the highest point or summit and is typically illustrated as a small circle on a topographic map with the AMSL height shown in metres, feet or both. In the rare case that a location is below sea level, for one such case, see Amsterdam Airport Schiphol
10.
Kerguelen Islands
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The Kerguelen Islands, also known as the Desolation Islands, are a group of islands in the southern Indian Ocean constituting one of the two exposed parts of the mostly submerged Kerguelen Plateau. They are among the most isolated places on Earth, located 450 km northwest of the uninhabited Heard Island and McDonald Islands and more than 3,300 km from Madagascar, the nearest populated location. The main island, Grande Terre, is 6,675 km2 in area and is surrounded by a further 300 smaller islands and islets, the climate is raw and chilly with frequent high winds throughout the year. The surrounding seas are generally rough and they remain ice-free year-round, there are no indigenous inhabitants, but France maintains a permanent presence of 45 to 100 scientists, engineers and researchers. There are no airports on the islands, so all travel, Kerguelen Islands appear as the Ile de Nachtegal on Philippe Buaches map from 1754 before the island was officially discovered in 1772. It is possible this early name was after Tasmans ship De Zeeuwsche Nachtegaal, on the Buache map, Ile de Nachtegal is located at 43°S, 72°E, about 6 degrees north and 2 degrees east of the accepted location of Grande Terre. The islands were discovered by the French navigator Yves-Joseph de Kerguelen-Trémarec on 12 February 1772. The next day Charles de Boisguehenneuc landed and claimed the island for the French crown, yves de Kerguelen organised a second expedition in 1773 and arrived at the baie de lOiseau by December of the same year. On 6 January 1774 he commanded his lieutenant, Henri Pascal de Rochegude, since the end of the whaling and sealing era, most of the islands species have been able to increase their population again. In 1800, Hillsborough spent eight months sealing and whaling around the islands, during this time Captain Robert Rhodes, her master, prepared a chart of the islands. In 1825, the British sealer John Nunn and three members from Favourite, were shipwrecked on Kerguelen until they were rescued in 1827 by Captain Alexander Distant during his hunting campaign. The islands were not completely surveyed until the Ross expedition of 1840, for the 1874 transit of Venus, George Biddell Airy at the Royal Observatory of the UK organised and equipped five expeditions to different parts of the world. Three of these were sent to the Kerguelen Islands, the Reverend Stephen Joseph Perry led the British expeditions to the Kerguelen Islands. He set up his main station at Observatory Bay and two auxiliary stations, one at Thumb Peak led by Sommerville Goodridge, and the second at Supply Bay led by Cyril Corbet. Observatory Bay was also used by the German Antarctic Expedition led by Erich Dagobert von Drygalski in 1902–03, in January 2007, an archaeological excavation of this site was carried out. In 1874–1875, British, German and U. S. expeditions visited Kerguelen to observe the transit of Venus, in 1877 the French started a coal mining operation, however, this was abandoned soon after. The German auxiliary cruiser Atlantis called at Kerguelen during December 1940, during their stay the crew performed maintenance and replenished their water supplies. This ships first fatality of the war occurred when a sailor, Bernhard Herrmann and he is buried in what is sometimes referred to as the most southerly German war grave of World War II
11.
France
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France, officially the French Republic, is a country with territory in western Europe and several overseas regions and territories. The European, or metropolitan, area of France extends from the Mediterranean Sea to the English Channel and the North Sea, Overseas France include French Guiana on the South American continent and several island territories in the Atlantic, Pacific and Indian oceans. France spans 643,801 square kilometres and had a population of almost 67 million people as of January 2017. It is a unitary republic with the capital in Paris. Other major urban centres include Marseille, Lyon, Lille, Nice, Toulouse, during the Iron Age, what is now metropolitan France was inhabited by the Gauls, a Celtic people. The area was annexed in 51 BC by Rome, which held Gaul until 486, France emerged as a major European power in the Late Middle Ages, with its victory in the Hundred Years War strengthening state-building and political centralisation. During the Renaissance, French culture flourished and a colonial empire was established. The 16th century was dominated by civil wars between Catholics and Protestants. France became Europes dominant cultural, political, and military power under Louis XIV, in the 19th century Napoleon took power and established the First French Empire, whose subsequent Napoleonic Wars shaped the course of continental Europe. Following the collapse of the Empire, France endured a succession of governments culminating with the establishment of the French Third Republic in 1870. Following liberation in 1944, a Fourth Republic was established and later dissolved in the course of the Algerian War, the Fifth Republic, led by Charles de Gaulle, was formed in 1958 and remains to this day. Algeria and nearly all the colonies became independent in the 1960s with minimal controversy and typically retained close economic. France has long been a centre of art, science. It hosts Europes fourth-largest number of cultural UNESCO World Heritage Sites and receives around 83 million foreign tourists annually, France is a developed country with the worlds sixth-largest economy by nominal GDP and ninth-largest by purchasing power parity. In terms of household wealth, it ranks fourth in the world. France performs well in international rankings of education, health care, life expectancy, France remains a great power in the world, being one of the five permanent members of the United Nations Security Council with the power to veto and an official nuclear-weapon state. It is a member state of the European Union and the Eurozone. It is also a member of the Group of 7, North Atlantic Treaty Organization, Organisation for Economic Co-operation and Development, the World Trade Organization, originally applied to the whole Frankish Empire, the name France comes from the Latin Francia, or country of the Franks
12.
Heard Island and McDonald Islands
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The groups overall size is 372 square kilometres in area and it has 101.9 km of coastline. Discovered in the century, the islands have been an Australian territory since 1947. The summit of one, Mawson Peak, is higher than any mountain on the Australian mainland, the islands lie on the Kerguelen Plateau in the Indian Ocean. Heard Island, by far the largest of the group, is a 368-square-kilometre bleak and its mountains are covered by 41 glaciers and dominated by Mawson Peak, a 2, 745-metre high complex volcano which forms part of the Big Ben massif. The McDonald Islands are located 44 kilometres to the west of Heard Island at 53°02′20″S 72°36′04″E, the islands are small and rocky. In 1980 they consisted of McDonald Island, Flat Island and Meyer Rock and they totalled approximately 2.5 square kilometres in area, where McDonald Island was 1.13 square kilometres. There is a group of islets and rocks about 10 kilometres north of Heard Island, consisting of Shag Islet, Sail Rock, Morgan Island. They total about 1.1 square kilometres in area, Mawson Peak and McDonald Island are the only two active volcanoes in Australian territory. Mawson Peak is also one of the highest Australian mountains, surpassed only by Mount McClintock range in the Antarctic territory, Mawson Peak has erupted several times in the last decade, the most recent eruption was filmed on 2 February 2016. The volcano on McDonald Island, after being dormant for 75,000 years, became active in 1992 and has erupted several times since, Heard Island and the McDonald Islands have no ports or harbours, ships must anchor offshore. The coastline is 101.9 kilometres, and a 12-nautical-mile territorial sea, the islands have an Antarctic climate, tempered by their maritime setting. The weather is marked by low seasonal and daily temperature ranges, persistent and generally low cloud cover, frequent precipitation and strong winds. Monthly average temperatures at Atlas Cove range from 0.0 to 4.2 °C, with an average range of 3.7 to 5.2 °C in summer. The winds are westerly and persistently strong. At Atlas Cove, monthly average wind speeds range between around 26 to 33.5 km/h, gusts in excess of 180 km/h have been recorded. Annual precipitation at sea level on Heard Island is in the order of 1,300 to 1,900 mm, meteorological records at Heard Island are incomplete. The islands are part of the Southern Indian Ocean Islands tundra ecoregion that includes several subantarctic islands, in this cold climate plant life is mainly limited to grasses, lichens, and mosses. Low plant diversity reflects the islands’ isolation, small size, severe climate, at Heard Island, exposure to salt spray and the presence of breeding and moulting seabirds and seals are particularly strong influences on vegetation composition and structure in coastal areas
13.
Volcanism
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It includes all phenomena resulting from and causing magma within the crust or mantle of the body, to rise through the crust and form volcanic rocks on the surface. Magma from the mantle or lower crust rises through its crust towards the surface, if magma reaches the surface, its behavior depends on the viscosity of the molten constituent rock. Viscous magma produces volcanoes characterised by explosive eruptions, while non-viscous magma produce volcanoes characterised by effusive eruptions pouring large amounts of lava onto the surface, in some cases, rising magma can cool and solidify without reaching the surface. Instead, the cooled and solidified igneous mass crystallises within the crust to form an igneous intrusion, as magma cools the chemicals in the crystals formed are effectively removed from the main mix of the magma, so the chemical content of the remaining magma evolves as it solidifies slowly. Fresh unevolved magma injections can remobilise more evolved magmas, allowing eruptions from more viscous magmas, movement of molten rock in the mantle, caused by thermal convection currents, coupled with gravitational effects of changes on the earths surface drive plate tectonic motion and ultimately volcanism. Volcanoes are places where magma reaches the earths surface, the type of volcano depends on the location of the eruption and the consistency of the magma. These are formed where magma pushes between existing rock, intrusions can be in the form of batholiths, dikes, sills, earthquakes are generally associated with plate tectonic activity, but some earthquakes are generated as a result of volcanic activity. These are formed where water interacts with volcanism and these include geysers, fumaroles, hotsprings and mudpots, they are often used as a source of geothermal energy. The amount of gas and ash emitted by volcanic eruptions has a significant effect on the Earths climate, large eruptions correlate well with some significant climate change events. When the magma cools it solidifies and forms rocks, the type of rock formed depends on the composition of the magma. Magma that reaches the surface to become lava cools rapidly resulting in rocks with small crystals such as basalt, some of this magma may cool extremely rapidly and will form volcanic glass such as obsidian. Magma that remains trapped below ground in thin intrusions cools slower than magma exposed to the surface, magma that remains trapped in large quantities below ground cools most slowly resulting in rocks with larger crystals - such as granite and gabbro. Existing rocks that come into contact with magma may be melted and assimilated into the magma, other rocks adjacent to the magma may be altered by contact metamorphism or metasomatism as they are affected by the heat and escaping or externally circulating hydrothermal fluids. Volcanism is not confined only to Earth, but is thought to be found on any body having a solid crust, evidence of volcanism should still be found on any body that has had volcanism at some point in its history. It can be surmised that volcanism exists on planets and moons of this type in other systems as well. In 2014, scientists found 70 lava flows which formed on the Moon in the last 100 million years, bimodal volcanism Continental drift Hotspot Volcanic arc Glossary of Volcanic Terms. G. J. Hudak, University of Wisconsin Oshkosh,2001, crumpler, L. S. and Lucas, S. G. Volcanoes of New Mexico, An Abbreviated Guide For Non-Specialists. New Mexico Museum of Natural History and Science Bulletin, archived from the original on 2007-03-21
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Volcanic plateau
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A volcanic plateau is a plateau produced by volcanic activity. There are two types, lava plateaus and pyroclastic plateaus. Lava plateaus are formed by highly fluid basaltic lava during numerous successive eruptions through numerous vents without violent explosions and these eruptions are quiet because of low viscosity of lava, so that it is very fluid and contains a small amount of trapped gases. Multiple successive and extensive lava flows cover the landscape to eventually form a plateau. In some cases, a plateau may be part of a single volcano. An example is the massive Level Mountain shield volcano in northern British Columbia, Canada, which covers an area of 1,800 km2 and a volume of 860 km3. Perhaps the most extensive of all the basaltic plateaus existed during the Paleogene. This region, known as the Thulean Plateau, is believed to have been broken up by foundering of the Earths crust to form the present ocean basin. The Earth features numerous subaerial and submarine volcanic plateaus such as the Columbia River Plateau, pyroclastic volcanic plateaus are produced by massive pyroclastic flows and they are underlain by pyroclastic rocks, agglomerates, tephra, volcanic ashes cemented into tuffs, mafic or felsic. Examples include Shirasu-Daichi which covers almost all of Southern Kyūshū, Japan and the North Island Volcanic Plateau in New Zealand
15.
Mid-ocean ridge
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A mid-ocean ridge is an underwater mountain system formed by plate tectonics. It consists of various mountains linked in chains, typically having a known as a rift running along its spine. This type of mountain ridge is characteristic of what is known as an oceanic spreading center. The production of new results from mantle upwelling in response to plate spreading. The buoyant melt rises as magma at a linear weakness in the oceanic crust, a mid-ocean ridge demarcates the boundary between two tectonic plates, and consequently is termed a divergent plate boundary. Mid-ocean ridges are geologically active, with new magma constantly emerging onto the floor and into the crust at. The crystallized magma forms new crust of basalt and gabbro and they are formed by two oceanic plates moving away from each other. The rocks making up the crust below the seafloor are youngest along the axis of the ridge and age with increasing distance from that axis, new magma of basalt composition emerges at and near the axis because of decompression melting in the underlying Earths mantle. The oceanic crust is made up of much younger than the Earth itself. Most oceanic crust in the basins is less than 200 million years old. The crust is in a constant state of renewal at the ocean ridges, moving away from the mid-ocean ridge, ocean depth progressively increases, the greatest depths are in ocean trenches. As the oceanic crust moves away from the axis, the peridotite in the underlying mantle cools. The crust and the relatively rigid peridotite below it make up the oceanic lithosphere, by contrast, fast spreading ridges like the East Pacific Rise are narrow, sharp incisions surrounded by generally flat topography that slopes away from the ridge over many hundreds of miles. The overall shape of ridges results from Pratt isostacy, close to the ridge there is hot. As the oceanic plates cool, away from the axes, the oceanic mantle lithosphere thickens. Thus older seafloor is underlain by denser material and sits lower, there are two processes, ridge-push and slab pull, thought to be responsible for the spreading seen at mid-ocean ridges, and there is some uncertainty as to which is dominant. Ridge-push occurs when the bulk of the ridge pushes the rest of the tectonic plate away from the ridge. At the subduction zone, slab-pull comes into effect and this is simply the weight of the tectonic plate being subducted below the overlying plate dragging the rest of the plate along behind it
16.
Ninety East Ridge
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The Ninety East Ridge is a linear structure on the Indian Ocean floor named for its near-parallel strike along the 90th meridian at the center of the Eastern Hemisphere. The ridge extends between latitudes 33°S and 17°N and has a width of 200 km. The ridge divides the Indian Ocean into the West and East Indian Ocean, the northeastern side is named the Wharton Basin and ceases at the western end of the Diamantina Fracture Zone which passes to the east and almost to the Australian continent. The ridge has been surveyed several times in the past, including several times by the Deep Sea Drilling Program and it had been assumed that the India and Australia are on a single tectonic plate for at least the last 32 million years. Eighty Five East Ridge Sager, William W. Cruise Report KNOX06RR R/V Roger Revelle 18 June to 6 August,2007, nobre Silva, I. G. Deciphering mantle source components in basalts from hotspot tracks and oceanic islands. Eisin, A. E. Frey, F. A. Rao, large fault fabric of the Ninetyeast Ridge implies near-spreading ridge formation. Verzhbitsky, E. V. Geothermal regime and genesis of the Ninety-East and Chagos-Laccadive ridges
17.
Bay of Bengal
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The Bay of Bengal, the largest bay in the world, forms the northeastern part of the Indian Ocean. Roughly triangular, it is bordered mostly by India and Sri Lanka to the west, Bangladesh to the north, and Myanmar, the Bay of Bengal occupies an area of 2,172,000 square kilometres. Among the important ports are Chennai, Chittagong, Colombo, Kolkata, Mongla, Paradip, Tuticorin, Visakhapatnam, on the south, Adams Bridge and from the southern extreme of Dondra Head to the north point of Poeloe Bras. The bay gets its name from the historical Bengal region, in ancient Hindu scriptures, this water body is referred to as Mahodadhi while it appears as Sinus Gangeticus or Gangeticus Sinus, meaning Gulf of the Ganges, in ancient maps. The other Sanskrit names for Bay of Bengal are Vangopasagara, also called as Vangasagara. Even today in Bengali, it is known as Bongoposagor, many major rivers of the Indian subcontinent flow west to east before draining into the Bay of Bengal. The Ganga is the northernmost of these and its main channel enters and flows through Bangladesh, where it is known as the Padma River, before joining the Meghna River. However, the Brahmaputra River flows from east to west in Assam before turning south and this joins the Padma whereupon the Padma joins the Meghna River that finally drains into Bay of Bengal. The Sundarbans mangrove forest at the delta of the Ganges, Brahmaputra and Meghna rivers lies partly in West Bengal, the Brahmaputra at 2,948 km is the 28th longest River in the world. The Hooghly River, another channel of the Ganga that flows through Calcutta drains into Bay of Bengal in India itself, the Ganga–Brahmaputra rivers deposits nearly 1000 million tons of sediment per year. The Bay of Bengal used to be deeper than the Mariana Trench, the fan has buried organic carbon at a rate of nearly 1.1 trillion mol/yr since the early Miocene period. The two rivers currently contribute nearly 8% of the organic carbon deposited in the worlds oceans. Due to high TOC accumulation in the sea bed of the Bay of Bengal. Bangladesh can reclaim land substantially and economically from the sea area by constructing sea dikes, bunds, causeways and by trapping the sediment from its rivers. Further south of Bengal, the Mahanadi, Godavari, Krishna and Kaveri Rivers are the rivers that flow from west to east in the Indian subcontinent. Many small rivers drain directly into the Bay of Bengal. The Irrawaddy River in Myanmar flows into the Andaman Sea of the Bay of Bengal, some of the biggest ports in the world — Chennai, Visakhapatnam, Paradip, Kolkata in India as well as Chittagong and Mongla in Bangladesh — are on the bay. Other Indian ports on the bay include Kakinada, Pondicherry, Dhamra, the islands in the bay are numerous, including the Andaman Islands, Nicobar and Mergui groups of India
18.
Hotspot (geology)
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In geology, the places known as hotspots or hot spots are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle. They may be on, near to, or far from plate boundaries. Currently, there are two hypotheses that attempt to explain their origins, one suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary. The other hypothesis is that lithospheric extension permits the passive rising of melt from shallow depths and this hypothesis considers the term hotspot to be a misnomer, asserting that the mantle source beneath them is, in fact, not anomalously hot at all. Well known examples include Hawaii, Iceland and Yellowstone and it was later postulated that hotspots are fed by narrow streams of hot mantle rising from the Earths core–mantle boundary in a structure called a mantle plume. Whether or not such mantle plumes exist is currently the subject of a controversy in Earth science. Estimates for the number of hotspots postulated to be fed by mantle plumes has ranged from about 20 to several thousands, over the years, Hawaii, Réunion, Yellowstone, Galápagos, and Iceland are some of the currently most active volcanic regions to which the hypothesis is applied. As a result, they are less explosive than subduction zone volcanoes, where hotspots occur in continental regions, basaltic magma rises through the continental crust, which melts to form rhyolites. These rhyolites can form violent eruptions, for example, the Yellowstone Caldera was formed by some of the most powerful volcanic explosions in geologic history. However, when the rhyolite is completely erupted, it may be followed by eruptions of basaltic magma rising through the same lithospheric fissures, the hotspot hypothesis is now closely linked to the mantle plume hypothesis. Hotspot volcanoes are considered to have a different origin from island arc volcanoes. The latter form over subduction zones, at converging plate boundaries, when one oceanic plate meets another, the denser plate is forced downward into a deep ocean trench. This plate, as it is subducted, releases water into the base of the plate. It is this that fuels a chain of volcanoes, such as the Aleutian Islands, the joint mantle plume/hotspot hypothesis envisages the feeder structures to be fixed relative to one another, with the continents and seafloor drifting overhead. The hypothesis thus predicts that time-progressive chains of volcanoes are developed on the surface, examples are Yellowstone, which lies at the end of a chain of extinct calderas, which become progressively older to the west. Another example is the Hawaiian archipelago, where islands become progressively older, boschi, L. Becker, T. W. Steinberger, B. Mantle plumes, Dynamic models and seismic images, break-up spots, Could the Pacific open as a consequence of plate kinematics. Towards A Better Understanding Of Hot Spot Volcanism, formation of Hotspots Raising Hot Spots Large Igneous Provinces Maria Antretter, PhD Thesis, Moving hotspots – Evidence from paleomagnetism and modeling Do Plumes Exist
19.
Southeast Indian Ridge
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The Southeast Indian Ridge is a mid-ocean ridge in the southern Indian Ocean. The SEIR is the spreading centre closest to the Kerguelen and Amsterdam–Saint-Paul hotspot, the SEIR has an intermediate full spreading rate of 65 mm/yr, and, because Antarctica is virtually stationary, this results in a northward ridge migration of half that rate. Spreading rates along the SEIR varies from 69 mm/yr near 88°E to 75 mm/yr near 120°E, during the past 1 Ma the Amsterdam–St. Paul hotspot has produced a 150×200 km plateau straddling on the SEIR, the ASP Plateau covers and area of 30,000 km2 and rises 500 m above the surrounding seafloor. Both Amsterdam and St. Paul are located on the Antarctic side within 40 km of the SEIR, north-east of the ASP Plateau a string of submarine volcanoes, 1−3 km-high and 40 km-wide, mark the track of the ASP hotspot across the Australian Plate. This track leads to the intersection of the Broken Ridge and Ninety East Ridge west of Australia, the ASP hotspot ceased to produce these volcanoes some 10−5 Ma when the SEIR started to interact with it and the hotspot started to build the shallow plateau. The Kerguelen hotspot, located more than 1,000 km from the SEIR, furthermore, there is an active submarine volcano, the 1100 m-high Boomerang Seamount,18 km north of Amsterdam Island near the SEIR. Analyses of the composition of basalts recovered from its caldera support that the ASP hotspot contributed to the formation of the Ninety East Ridge. Trending east-west between Australia and Antarctica, the SEIR traverses the Australian-Antarctic Discordance, a complex region overlying an area of mantle down-welling. Between the AAD and the Amsterdam and St. Paul islands and this has been interpreted as an eastward decrease in mantle temperature of perhaps 100 °C caused by a magma flow from the Kerguelen–ASP hotspots to the AAD cold spot at 120–128°E. Located at 126°E, the AAD would thus mark the 40 km-long transition between Indian Ocean and Pacific MORBs, a boundary that has been migrating westward during the past tens of million years, together these features indicate the two tectonic plate made a recent counter-clockwise change in relative motion. Between 88°E and 118°E there are nine transform faults offsetting the SEIR 21–135 km or an age of 0. 5–3.6 Ma, accompanied by eight first-order segments and these transform faults and migrating rifts are located were the SEIR reaches its maximum axial depths. The first-order transform faults are off-set 2–17 km by 19 non-transform discontinuities, the flanks of the SEIR are dominated by fracture zones perpendicular to the ridge and gravitational lineations oblique to the spreading direction and sometimes zigzag-shaped. This suggests that the SEIR evolves rapidly within the framework of the transform faults. Australia and Antarctica were neighbours before the break-up of Gondwana in the Cretaceous, in south-western Australia the Albany-Fraser Orogen formed during the Mesoproterozoic collision between the Australian Yilgarn and Antarctic Mawson cratons. The continental basement of the submarine Naturaliste Plateau is also associated with this orogeny, the Darling Fault on the Australian west coast has a possible continuation beneath the Antarctic Denman Glacier. Archaean and Paleoproterzoic rocks in the Kalinjala Mylonite Zone of the Eyre Peninsula, Australia, match those found in Terre Adelie in Eastern Wilkes Land, faults in Tasmania–Victoria and Northern Victoria Land have been identified as Cambrian remains of the west-dipping subduction zone along the eastern margin of Gondwana. Australia and Antarctica broke-up around 110 Ma but spreading in the SEIR first began during the Eocene when the Kerguelen hotspot separated Broken Ridge from the rest of the Kerguelen Plateau, the SEIR has been migrating northeast since and is now located 1400 km from the Kerguelen hotspot
20.
Rodrigues Triple Junction
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The triple junction is named for the island of Rodrigues which lies 1,000 km north-west of it. The RTJ was first recognized in 1971, then described as a stable R-R-R triple junction based on coarse ship data, the boundaries of the three plates which meet at the Rodrigues Triple Junction are all oceanic spreading centers, making it an R-R-R type triple junction. They are, the Central Indian Ridge with a rate of 50 mm/yr, the Southwest Indian Ridge 16 mm/yr. The spreading rate is similar in the CIR but slower and the ridge has a complex geometry. The SWIR has ultra-slow spreading rates, a rough topography, for example, the East African Rift divides Africa into the Nubian and Somalian plates. The RTJ was born when the Seychelles microcontinent drifted off the Indian Plate at 64 Ma, since then the RTJ has moved eastward from south of Madagascar to its current location. Since 65 Ma the RTJ has been migrating north-east at a rate, originally the velocity was 10 cm/yr, at 43 Ma 2.6 cm/yr. The stability in migration rate around 41 Ma coincide with the bend in the Hawaiian–Emperor seamount chain — hinting at a global reorganisation of tectonic plates at this time and this is a configuration similar to that of the Galapagos Triple Junction in the east Pacific. Each time the RTJ offset eastward a new segment is added to CIR. resulting in a constant length for the CEIR while CIR constantly lengthens. Spreading rates in the SWIR, in contrast, is intermittent and very slow, but the extension of the plates in the SEIR and CIR causes constant lengthening of the SWIR near the RTJ
21.
Cooperation Sea
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It would stretch over an area of 258,000 km². It would be bordered by the Davis Sea on the east, and by another Russian proposal to the 2002 International Hydrographic Organization draft, the Cooperation Sea was named in 1962 by the Soviet Antarctic Expedition in honor of international science cooperation in Antarctica. The name first appeared as a proposal to the IHO in the IHO2002 draft and this draft was never approved by the IHO, and the 1953 IHO document remains currently in force. But Soviet and Russian-issued maps do, Davis Station is located on the coast near here
22.
Naturaliste Plateau
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The Naturaliste Plateau is one of several large submarine plateaus extending from Western Australia into the Indian Ocean. It is a plateau that covers an area of 90,000 square kilometres. Its width is about 400 kilometres east-west and 250 km north-south, the water depths are from 1500 to 5000 metres. The Mentelle Basin and Naturaliste Trough lie between the mainland and this plateau, the plateau is bordered by the Perth Abyssal Plain in the north and west and the Australian-Antarctic Basin in the south. It is within the Australian marine reserve known as the South-west Corner Commonwealth Marine Reserve, the Naturaliste Plateau formed during the Early Cretaceous 136 Ma when Australia and India broke up and during the Late Cretaceous 83 Ma when Australia and Antarctica broke up. The eastern flank of the plateau slopes gently, while the other three flanks are relatively steep. The southern flank formed during the Australia-Antarctica break-up, the flanks during the rifting between India and Australia. The continent ocean transition is 30–90 km wide on the side and 250 km on the southern side where the plateau is flanked by the Diamantina Fracture Zone. South of the plateau, during some 45 Ma after India and this rifting continued until sea-floor spreading began 83 Ma. Continental metamorphic and granitic basement rocks have been dredged from both knolls, protolith granite from Gulden Draak was emplaced in either the Australian Yilgarn Craton or the Antarctic Mawson Craton 2850 Ma. The Mesoproterozoic crust from this knoll is coeval with crust from the Naturaliste Plateau, neoproterozoic-Cambrian granite gneisses from the Batavia Knoll were emplaced during or after the formation of the Kuunga Orogen
23.
Rajmahal Traps
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The Rajmahal Traps is a volcanic igneous province in Eastern India, covering the parts of Jharkhand, West Bengal and Meghalaya. Rajmahal hills of Jharkhand is the area of this province. Multiple layers of solidified lava made 608 m thick Rajmahal hill which is dipping 2°-5° towards north-east, individual layers vary in thickness from less than 1 metre to more than 70 meters. These volcanic rocks were formed from the eruptions of the Kerguelen hotspot in the early Cretaceous, the similarity between the geochemical data of Rajmahal volcanis and lavas of the Kerguelen Plateau confirms this. According to the plate tectonics, the Indian subcontinent was over this hot spot during the Cretaceous age, the original lava flow covered an area of nearly 4,100 km2. Below the Bengal basin the flows cover 200,000 km2, the Rajmahal volcanics are predominantly tholeiitic basalt, quartz tholeiite, olivine tholeiite and alkali basalt. The Intertrappean Beds are composed of rock like siltstone, claystone. The western boundary of the Rajmahal Traps is faulted and down-thrown towards the east, the eastern boundary of this trap has a North-South trending, fault-controlled basement. This basement connects the Purnea basin of the Ganga valley with the Bengal basin and these faulted contacts, along with the Damodar Gondwana graben, form a triple junction at the mouth of the Bengal basin. The trap evolved along the eastern continental margin of India. Over the epochs, the part of the lava deformed in a cold, brittle fashion. The Intertrappean Beds contain assamblage of lower cretaceous plant fossil, the assemblage includes Cladophlebis indica, Dictyozamites indicus, Taeniopteris spatulata, Brachyphyllum rhombium
24.
Lamprophyre
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Lamprophyres are uncommon, small volume ultrapotassic igneous rocks primarily occurring as dikes, lopoliths, laccoliths, stocks and small intrusions. They are alkaline silica-undersaturated mafic or ultramafic rocks with high magnesium oxide, >3% potassium oxide, high sodium oxide and high nickel, lamprophyres occur throughout all geologic eras. Archaean examples are commonly associated with gold deposits. Cenozoic examples include magnesian rocks in Mexico and South America, modern science treats lamprophyres as a catch-all term for ultrapotassic mafic igneous rocks which have primary mineralogy consisting of amphibole or biotite, and with feldspar in the groundmass. They are classified under the IUGS Nomenclature for Igneous Rocks separately, for example, the TAS scheme is inappropriate due to the control of mineralogy by potassium, not by calcium or sodium. Classification schemes which include information, may be required to properly describe lamprophyres. Rock considered lamprophyres are part of a clan of rocks, with similar mineralogy, textures, lamprophyres are similar to lamproites and kimberlites. While modern concepts see orangeites, lamproites and kimberlites as separate, Mitchell considered the lamprophyres as a facies of igneous rocks created by a set of conditions. Either scheme may apply to some, but not all, occurrences and variations of the group of rocks known as lamprophyres. Rock considered lamprophyres to be derived from deep, volatile-driven melting in a subduction zone setting, others such as Mitchell consider them to be late offshoots of plutons, etc. though this can be difficult to reconcile with their primitive melt chemistry and mineralogy. Lamprophyres are a group of rocks containing phenocrysts, usually of biotite and amphibole, and pyroxene and they are thus distinguished from the porphyries and porphyrites in which the feldspar has crystallized in two generations. They are essentially dike rocks, occurring as dikes and thin sills and they are usually dark in color, owing to the abundance of ferro-magnesian silicates, of high specific gravity and liable to decomposition. For these reasons they have defined as a melanocrate series. Biotite and amphibole are panidiomorphic, all are euhedral, well formed, feldspar is restricted to the ground mass. In many lamprophyres the pale quartz and felspathic ingredients tend to occur in rounded spots, or ocelli and these spots may consist of radiate or brush-like feldspars or of quartz and feldspar. A central area of quartz or of analcite probably represents an original miarolitic cavity infilled at a later period, the presence or absence of the four dominant minerals, orthoclase, plagioclase, biotite and hornblende, determines the species, Minette contains biotite and orthoclase. Each variety of lamprophyre may and often contain all four minerals but is named according to the two which predominate. These rocks contain iron oxides, apatite, sometimes sphene, augite
25.
Walvis Ridge
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The Walvis Ridge is an aseismic ocean ridge in the southern Atlantic Ocean. More than 3,000 km in length, it extends from the Mid-Atlantic Ridge, near Tristan da Cunha, the Walvis Ridge is one of few examples of a hotspot seamount chain that links a flood basalt province to an active hotspot. It is also considered one of the most important hotspot tracks because the Tristan Hotspot is one of few primary or deep mantle hotspots, apart from the Mid-Atlantic Ridge, the Walvis Ridge and the Rio Grande Rise are the most distinctive feature of the South Atlantic sea floor. They originated from hotspot volcanism and together form a mirrored symmetry across the Mid-Atlantic Ridge. The Walvis Ridge is divided into three sections, A first 600 km long segment stretching from Africa to approximately longitude 6°E. A second section,500 km long, stretching north-south, a third more discontinuous section, which is marked by seamounts and connects the Walvis Ridge to the Mid-Atlantic Ridge. Cretaceous kimberlites in the central Democratic Republic of Congo and Angola align with the Walvis Ridge, the Tristan-Gough hotspot track first formed over the mantle plume that formed the Etendeka-Paraná continental flood basalts some 135 to 132 Ma. The eastern section of the ridge is thought to have created in the Middle Cretaceous period. While the mantle plume remained large and stable, the eastern Walvis Ridge formed along with the Rio Grande Rise over the Mid-Atlantic Ridge. During the Maastrichtian 60 million years ago, the orientation of spreading changed, the mantle plume then gradually became unstable and bifurcated 60 to 70 Ma to produce the two separate Tristan and Gough hotspot tracks. It finally disintegrated 35 to 45 Ma and formed the province in the western end of the ridge. Hundreds of volcanic explosions were recorded on the Walvis Ridge in 2001 and 2002 and these explosions seemed to come from an unnamed seamount on the northern side of the ridge and are thought to be unrelated to the Tristan hotspot. The Ewing Seamount is part of the ridge, the Eocene Layer of Mysterious Origin is a period of global warming that occurred 53.7 Ma, about two million years after the Paleocene–Eocene Thermal Maximum. This period manifests as a red clay layer unique to the Walvis Ridge and is similar to the PETM. The Walvis Ridge is an obstacle for the Agulhas rings. In average, five rings are shed each year, a number that varies considerably between years. The rings tend cross the Walvis Ridge at its deepest part, the rings can cross the South Atlantic in 2. 5–3 years but only two thirds make it farther than the Walvis Ridge. The Agulhas rings transport an estimated 1-5 Sv of water from the Indian Ocean to the South Atlantic, originating around Antarctica, Antarctic Bottom Water enters the Cape Basin between the Agulhas Bank and the Agulhas Ridge after which it flows west north of the Agulhas Ridge
26.
Rio Grande Rise
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The Rio Grande Rise is an aseismic ocean ridge in the southern Atlantic Ocean off the coast of Brazil. Together with the Walvis Ridge off Africa, the Rio Grande Rise forms a V-shaped structure of mirrored hotspot tracks or seamount chains across the northern South Atlantic, other researchers, however, noted that such boulders can end-up on the ocean floor by less speculative means. The Rio Grande Rise separates the Santos and Pelotas Basins and is composed of western and eastern areas, the western area has numerous guyots and seamounts and a basement dated to 80 to 87 million years ago. The eastern area is covered by zones and may represent an abandoned spreading centre. In the western area, volcanic breccia and layers of ash indicate widespread volcanism during the Eocene, during this period, parts of the western plateau were uplifted over sea level and short-lived volcanic islands formed. When West Gondwana broke away from Africa during the Early Cretaceous, in this process, the voluminous Paraná and Etendeka continental flood basalts formed in what is now Brazil and Namibia. This event is linked to the Tristan-Gough hotspot, now located near the Mid-Atlantic Ridge, close to Tristan da Cunha, during the Maastrichtian, the orientation of spreading changed, which is still visible on the African side, and volcanism ended on the American side. This process resulted in the Tristan-Gough seamount chains on either side of the Tristan-Gough hotspot, a Brazilian-Japanese expedition in 2013 recovered in situ granitic and metamorphic rocks on the Rio Grande Rise. The existence of such microcontinents is speculative, however, since their remains tend to be covered by layers of lava. At the beginning of the Maastritchian, the characteristics of water masses differed north and south of the Rio Grande Rice-Walvis Ridge complex, the disappearance of these differences during the Maastritchtian indicates a reorganisation of oceanic circulation patterns that lead to a global homogenisation of intermediate and deep waters. This process seems to have triggered by the breaching of the Rio Grande Rise-Walvis Ridge complex. The process resulted in the deterioration of rudist-dominated tropical habitats and consequently the extinction of benthic inoceramid bivalves. 40 Ma, the generation of cold water in the Antarctic resulted in the formation of psychrospheric fauna
27.
Chagos-Laccadive Ridge
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The Chagos-Laccadive Ridge, also known as Chagos-Laccadive Plateau, is a prominent volcanic ridge and oceanic plateau extending between the Northern and the Central Indian Ocean. The CLR extends northward for approximately 2350 km from 9°S at the end of the Chagos Archipelago to 14° north around the Adas Bank. The islands of Chagos, the Maldives and Lakshadweep are the parts of the Chagos-Laccadive Ridge. The vast Chagos-Laccadive Ridge was formed by the Réunion volcanic hotspot along with the part of the Mascarene Plateau. Both plateaux are volcanic traces of the Réunion hotspot, Central Indian Ridge Origin and compensation of Chagos-Laccadive ridge, Indian ocean, from admittance analysis of gravity and bathymetry data Hydrographic Description
28.
Deccan Traps
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The Deccan Traps are a large igneous province located on the Deccan Plateau of west-central India and one of the largest volcanic features on Earth. They consist of layers of solidified flood basalt that together are more than 2,000 m thick, cover an area of c.500,000 km2. Originally, the Deccan Traps may have covered c.1,500,000 km2, the term trap has been used in geology since 1785–95 for such rock formations. It is derived from the Scandinavian word for stairs and refers to the hills forming the landscape of the region. The Deccan Traps began forming 66.25 million years ago, the bulk of the volcanic eruption occurred at the Western Ghats some 66 million years ago. This series of eruptions may have lasted less than 30,000 years in total, the original area covered by the lava flows is estimated to have been as large as 1.5 million km², approximately half the size of modern India. The Deccan Traps region was reduced to its current size by erosion and plate tectonics, the release of volcanic gases, particularly sulphur dioxide, during the formation of the traps contributed to contemporary climate change. Data points to a drop in temperature of 2 °C in this period. Because of its magnitude, scientists formerly speculated that the released during the formation of the Deccan Traps played a role in the Cretaceous–Paleogene extinction event. However, the current consensus among the community is that the extinction was triggered by the Chicxulub impact event in North America. Work published in 2014 by geologist Gerta Keller and others on the timing of the Deccan volcanism suggests the extinction may have been caused by both the volcanism and the impact event and this was followed by a similar study in 2015. Within the Deccan Traps at least 95% of the lavas are tholeiitic basalts, however, other rock types do occur, Alkali basalts Nephelinites Lamprophyre Carbonatites Mantle xenoliths have been described from Kachchh and elsewhere in the western Deccan. The Deccan Traps are famous for the beds of fossils that have found between layers of lava. The infratrappean and intertrappean beds also contain fossil freshwater mollusks and it is postulated that the Deccan Traps eruption was associated with a deep mantle plume. The area of long-term eruption, known as the Réunion hotspot, is suspected of causing the Deccan Traps eruption and opening the rift that once separated the Seychelles plateau from India. Seafloor spreading at the boundary between the Indian and African Plates subsequently pushed India north over the plume, which now lies under Réunion island in the Indian Ocean, the mantle plume model has, however, been challenged. Data continues to emerge which supports the plume model, the motion of the Indian tectonic plate and the eruptive history of the Deccan traps show strong correlations. Based on data from marine magnetic profiles, a pulse of unusually rapid plate motion begins at the time as the first pulse of Deccan flood basalts
29.
Seychelles
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Seychelles, officially the Republic of Seychelles, is an archipelago and country in the Indian Ocean. The 115-island country, whose capital is Victoria, lies 1,500 kilometres east of mainland East Africa, other nearby island countries and territories include Comoros, Mayotte, Madagascar, Réunion and Mauritius to the south. Seychelles is a member of the African Union, the Southern African Development Community, the Commonwealth of Nations, since 1976, per capita output has increased nearly sevenfold. In recent years, the government has encouraged investment in order to upgrade these sectors. Today, Seychelles boasts the highest nominal per capita GDP in Africa and it is one of only a handful of countries in Africa with high Human Development Index. Despite the countrys economic prosperity, poverty remains widespread due to very high level of income inequality, one of the highest in the world. The Seychelles were uninhabited throughout most of recorded history, some scholars assume that Austronesian seafarers and later Maldivian and Arab traders were the first to visit the uninhabited Seychelles. This assumption is based on the discovery of tombs in 1910, the earliest recorded sighting by Europeans took place in 1502 by the Portuguese Admiral Vasco da Gama, who passed through the Amirantes and named them after himself. The earliest recorded landing was in January 1609, by the crew of the Ascension under Captain Alexander Sharpeigh during the voyage of the British East India Company. The islands were named after Jean Moreau de Séchelles, Louis XVs Minister of Finance, the British controlled the islands between 1794 and 1810. Jean Baptiste Quéau de Quincy, French administrator of Seychelles during the years of war with the United Kingdom, instead, he successfully negotiated the status of capitulation to Britain which gave the settlers a privileged position of neutrality. Britain eventually assumed full control upon the surrender of Mauritius in 1810, Seychelles became a crown colony separate from Mauritius in 1903. Elections were held in 1966 and 1970, independence was granted in 1976 as a republic within the Commonwealth. In the 1970s Seychelles was the place to be seen, a playground for film stars, in 1977, a coup détat by France Albert René ousted the first president of the republic, James Mancham. René discouraged over-dependence on tourism and declared that he wanted to keep the Seychelles for the Seychellois, the 1979 constitution declared a socialist one-party state, which lasted until 1991. In the 1980s there were a series of attempts against President René. In 1981, Mike Hoare led a team of 43 South African mercenaries masquerading as holidaying rugby players in the 1981 Seychelles coup détat attempt, there was a gun battle at the airport, and most of the mercenaries later escaped in a hijacked Air India plane. The leader of this hijacking was German mercenary D. Clodo, Clodo later stood trial in South Africa as well as in his home country Germany for air-piracy
30.
Charcoal
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Charcoal is a lightweight, black residue, consisting of carbon and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis- the heating of wood or other substances in the absence of oxygen, the whole pile is covered with turf or moistened clay. The firing is begun at the bottom of the flue, the success of the operation depends upon the rate of the combustion. The operation is so delicate that it was left to colliers. They often lived alone in small huts in order to tend their wood piles, for example, in the Harz Mountains of Germany, charcoal burners lived in conical huts called Köten which are still much in evidence today. The massive production of charcoal was a cause of deforestation. The increasing scarcity of easily harvested wood was a factor behind the switch to fossil fuel equivalents, mainly coal. Charcoal made at 300 °C is brown, soft and friable, and readily inflames at 380 °C, made at higher temperatures it is hard and brittle, in Finland and Scandinavia, the charcoal was considered the by-product of wood tar production. The best tar came from pine, thus pinewoods were cut down for tar pyrolysis, the residual charcoal was widely used as substitute for metallurgical coke in blast furnaces for smelting. Tar production led to deforestation, it has been estimated all Finnish forests are younger than 300 years. The end of tar production at the end of the 19th century resulted in rapid re-forestation, the charcoal briquette was first invented and patented by Ellsworth B. A. Zwoyer of Pennsylvania in 1897 and was produced by the Zwoyer Fuel Company. The process was popularized by Henry Ford, who used wood. Ford Charcoal went on to become the Kingsford Company, Charcoal has been made by various methods. The traditional method in Britain used a clamp and this is essentially a pile of wooden logs leaning against a chimney. The chimney consists of 4 wooden stakes held up by some rope, the logs are completely covered with soil and straw allowing no air to enter. It must be lit by introducing some burning fuel into the chimney, if the soil covering gets torn by the fire, additional soil is placed on the cracks. Once the burn is complete, the chimney is plugged to prevent air from entering, the true art of this production method is in managing the sufficient generation of heat, and its transfer to wood parts in the process of being carbonised. A strong disadvantage of this method is the huge amount of emissions that are harmful to human health
31.
Conglomerate (geology)
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Conglomerates form by the consolidation and lithification of gravel. The size and composition of the fraction of a conglomerate may or may not vary in composition, sorting. In some conglomerates, the gravel-size class consist almost entirely of what were clay clasts at the time of deposition, conglomerates can be found in sedimentary rock sequences of all ages but probably make up less than 1 percent by weight of all sedimentary rocks. A sedimentary rock composed largely of gravel is first named according to the roundness of the gravel, if the gravel clasts that comprise it is largely well-rounded to subrounded, it is a conglomerate. If the gravel clasts that comprise it are largely angular, it is a breccia, such breccias can be called sedimentary breccias to differentiate them from other types of breccia, e. g. volcanic and fault breccias. Sedimentary rocks that contain a mixture of rounded and angular gravel clasts are sometimes called breccio-conglomerate, conglomerates are rarely composed entirely of gravel-size clasts. Typically, the space between the gravel-size clasts is filled by a mixture composed of varying amounts of silt, sand, paraconglomerates are also often unstratified and can contain more matrix than gravel clasts. If the gravel clasts of a conglomerate are in contact with each other, unlike paraconglomerates, orthoconglomerates are typically cross-bedded and often well-cemented and lithified by either calcite, hematite, quartz, or clay. The differences between paraconglomerates and orthoconglomerates reflect differences in how they are deposited, paraconglomerates are commonly either glacial tills or debris flow deposits. Orthoconglomerates are typically associated with aqueous currents, conglomerates are also classified according to the composition of their clasts. A conglomerate or any clastic sedimentary rock that consists of a rock or mineral is known as either a monomict, monomictic, oligomict. If the conglomerate consists of two or more different types of rocks, minerals, or combination of both, it is known as either a polymict or polymictic conglomerate. If a polymictic conglomerate contains an assortment of the clasts of metastable and unstable rocks and minerals, two recognized types of type of intraformational conglomerates are shale-pebble and flat-pebble conglomerates. Finally, conglomerates are often differentiated and named according to the dominant clast size comprising them, conglomerates are deposited in a variety of sedimentary environments. In turbidites, the part of a bed is typically coarse-grained. In this setting, conglomerates are normally very well sorted, well-rounded, conglomerates are normally present at the base of sequences laid down during marine transgressions above an unconformity, and are known as basal conglomerates. They represent the position of the shoreline at a time and are diachronous. Conglomerates deposited in environments are typically well rounded and well sorted
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Gneiss
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Gneiss is a common distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks. The foliations are characterized by alternating darker and lighter colored bands, the word gneiss comes from the Middle High German verb gneist. It has occurred in English since at least 1757, gneissic rocks are usually medium- to coarse-foliated, they are largely recrystallized but do not carry large quantities of micas, chlorite or other platy minerals. Gneisses that are metamorphosed igneous rocks or their equivalent are termed granite gneisses, diorite gneisses, gneiss rocks may also be named after a characteristic component such as garnet gneiss, biotite gneiss, albite gneiss, etc. Orthogneiss designates a gneiss derived from a rock, and paragneiss is one from a sedimentary rock. Gneissose rocks have properties similar to gneiss, gneiss appears to be striped in bands, called gneissic banding. The banding is developed under high temperature and pressure conditions, the minerals are arranged into layers that appear as bands in cross section. The appearance of layers, called compositional banding, occurs because the layers, the darker bands have relatively more mafic minerals. The lighter bands contain relatively more felsic and these forces stretch out the rock like a plastic, and the original material is spread out into sheets. Another cause of banding is metamorphic differentiation, which separates different materials into different layers through chemical reactions, not all gneiss rocks have detectable banding. In kyanite gneiss, crystals of kyanite appear as random clumps in what is mainly a plagioclase matrix, henderson gneiss is found in North Carolina and South Carolina, US, east of the Brevard Shear Zone. It has deformed into two sequential forms, the second, more warped, form is associated with the Brevard Fault, and the first deformation results from displacement to the southwest. Most of the Outer Hebrides of Scotland have a formed from Lewisian gneiss. In addition to the Outer Hebrides, they form basement deposits on the Scottish mainland west of the Moine Thrust and on the islands of Coll and Tiree. These rocks are igneous in origin, mixed with metamorphosed marble, quartzite and mica schist with later intrusions of basaltic dikes. Gneisses of Archean and Proterozoic age occur in the Baltic Shield, in antiquity, gneisses were also utilized in architectural construction. They were used to erect the Sphinx of Taharqo in the Nile Valley, list of rock types Blatt, Harvey and Robert J. Tracy. Petrology, Igneous, Sedimentary and Metamorphic, 2nd ed. Freeman, mcKirdy, Alan, Roger Crofts and John Gordon
33.
Wildfire
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A wildfire or wildland fire is a fire in an area of combustible vegetation that occurs in the countryside or rural area. Fossil charcoal indicates that wildfires began soon after the appearance of terrestrial plants 420 million years ago, wildfire’s occurrence throughout the history of terrestrial life invites conjecture that fire must have had pronounced evolutionary effects on most ecosystems flora and fauna. Earth is an intrinsically flammable planet owing to its cover of vegetation, seasonally dry climates, atmospheric oxygen, widespread lightning. Wildfires can be characterised in terms of the cause of ignition, their properties, the combustible material present. Wildfires can cause damage to property and human life, but they have beneficial effects on native vegetation, animals. Many plant species depend on the effects of fire for growth, however, wildfire in ecosystems where wildfire is uncommon or where non-native vegetation has encroached may have negative ecological effects. Wildfire behaviour and severity result from the combination of such as available fuels, physical setting. Strategies of wildfire prevention, detection and suppression have varied over the years, one common and inexpensive technique is controlled burning, permitting or even igniting smaller fires to minimise the amount of flammable material available for a potential wildfire. Vegetation may be burned periodically to maintain species diversity and frequent burning of surface fuels limits fuel accumulation. Wildland fire use is the cheapest and most ecologically appropriate policy for many forests, fuels may also be removed by logging, but fuels treatments and thinning have no effect on severe fire behaviour. Wildfires can also be started in communities experiencing shifting cultivation, where land is cleared quickly and farmed until the soil loses fertility, forested areas cleared by logging encourage the dominance of flammable grasses, and abandoned logging roads overgrown by vegetation may act as fire corridors. The most common cause of wildfires throughout the world. In Canada and northwest China, for example, lightning operates as the source of ignition. In other parts of the world, human involvement is a major contributor, in China and in the Mediterranean Basin, human carelessness is a major cause of wildfires. In the United States and Australia, the source of wildfires can be traced both to lightning strikes and to human activities. Coal seam fires burn in the thousands around the world, such as those in Burning Mountain, New South Wales, Centralia, Pennsylvania and they can also flare up unexpectedly and ignite nearby flammable material. The spread of wildfires based on the flammable material present, its vertical arrangement and moisture content. Fuel arrangement and density is governed in part by topography, as land shape determines factors such as available sunlight, overall, fire types can be generally characterized by their fuels as follows, Ground fires are fed by subterranean roots, duff and other buried organic matter
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Cretaceous
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The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago to the beginning of the Paleogene Period 66 Mya. It is the last period of the Mesozoic Era, the Cretaceous Period is usually abbreviated K, for its German translation Kreide. The Cretaceous was a period with a warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct marine reptiles, ammonites and rudists, during this time, new groups of mammals and birds, as well as flowering plants, appeared. The Cretaceous ended with a mass extinction, the Cretaceous–Paleogene extinction event, in which many groups, including non-avian dinosaurs, pterosaurs. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary, the name Cretaceous was derived from Latin creta, meaning chalk. The Cretaceous is divided into Early and Late Cretaceous epochs, or Lower and Upper Cretaceous series, in older literature the Cretaceous is sometimes divided into three series, Neocomian, Gallic and Senonian. A subdivision in eleven stages, all originating from European stratigraphy, is now used worldwide, in many parts of the world, alternative local subdivisions are still in use. As with other geologic periods, the rock beds of the Cretaceous are well identified. No great extinction or burst of diversity separates the Cretaceous from the Jurassic and this layer has been dated at 66.043 Ma. A140 Ma age for the Jurassic-Cretaceous boundary instead of the usually accepted 145 Ma was proposed in 2014 based on a study of Vaca Muerta Formation in Neuquén Basin. Víctor Ramos, one of the authors of the study proposing the 140 Ma boundary age sees the study as a first step toward formally changing the age in the International Union of Geological Sciences, due to the high sea level there was extensive space for such sedimentation. Because of the young age and great thickness of the system. Chalk is a type characteristic for the Cretaceous. It consists of coccoliths, microscopically small calcite skeletons of coccolithophores, the group is found in England, northern France, the low countries, northern Germany, Denmark and in the subsurface of the southern part of the North Sea. Chalk is not easily consolidated and the Chalk Group still consists of sediments in many places. The group also has other limestones and arenites, among the fossils it contains are sea urchins, belemnites, ammonites and sea reptiles such as Mosasaurus. In southern Europe, the Cretaceous is usually a marine system consisting of competent limestone beds or incompetent marls
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Sperm whale
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The sperm whale, or cachalot, is the largest of the toothed whales and the largest toothed predator. It is the only living member of genus Physeter, and one of three extant species in the whale family, along with the pygmy sperm whale and dwarf sperm whale of the genus Kogia. Mature males average 16 metres in length but some may reach 20.5 metres, plunging to 2,250 metres, it is the second deepest diving mammal, following only the Cuviers beaked whale. The sperm whales clicking vocalization, a form of echolocation and communication and it has the largest brain of any animal on Earth, more than five times heavier than a humans. Sperm whales can live for more than 60 years, the sperm whale can be found anywhere in the open ocean. Females and young males live together in groups while males live solitary lives outside of the mating season. The females cooperate to protect and nurse their young, females give birth every four to twenty years, and care for the calves for more than a decade. A mature sperm whale has few predators, although calves. From the early eighteenth century through the late 20th, the species was a target of whalers. The head of the whale contains a liquid wax called spermaceti, spermaceti was used in lubricants, oil lamps, and candles. Ambergris, a product from its digestive system, is still used as a fixative in perfumes. Occasionally the sperm whales great size allowed it to defend effectively against whalers. The species is now protected by a moratorium, and is currently listed as vulnerable by the International Union for the Conservation of Nature. The name sperm whale is a clip of spermaceti whale, spermaceti, originally mistakenly identified as the whales semen, is the semi-liquid, waxy substance found within the whales head. The sperm whale is known as the cachalot, which is thought to derive from the archaic French for tooth or big teeth. The etymological dictionary of Corominas says the origin is uncertain, but it suggests that it comes from the Vulgar Latin cappula, plural of cappulum, the word cachalot came to English via French from Spanish or Portuguese cachalote, perhaps from Galician/Portuguese cachola, big head. The term is retained in the Russian word for the animal, кашалот, the scientific genus name Physeter comes from Greek physētēr, meaning blowpipe, blowhole, or – as a pars pro toto – whale. The specific name macrocephalus is Latinized from the Greek makrokephalos, from makros + kefalos and its synonymous specific name catodon means down-tooth, from the Greek elements cat- and odṓn, so named because it has visible teeth only in its lower jaw
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Baleen whale
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Baleen whales, known earlier as whalebone whales, form a parvorder of the infraorder Cetacea. They are a widely distributed and diverse parvorder of carnivorous marine mammals, Mysticeti comprise the families Balaenidae, Balaenopteridae, Cetotheriidae, and Eschrichtiidae. There are currently 15 species of baleen whale, while cetaceans were historically thought to have descended from mesonychids, molecular evidence supports them as relatives of even-toed ungulates. Baleen whales split from toothed whales around 34 million years ago, baleen whales range in size from the 20 ft and 6,600 lb pygmy right whale to the 112 ft and 190 t blue whale, which is also the largest creature on earth. Baleen whales can have streamlined or large bodies, depending on the feeding behavior, though not as flexible and agile as seals, baleen whales can swim very fast, with the fastest able to travel at 23 miles per hour. Baleen whales use their baleen plates to filter out food from the water by either lunge-feeding or skim-feeding, baleen whales have fused neck vertebrae, and are unable to turn their head at all. Some species are adapted for diving to great depths. They have a layer of fat, or blubber, under the skin to keep warm in the cold water, although baleen whales are widespread, most species prefer the colder waters around the Northern and Southern poles. Gray whales are specialized for feeding on bottom-dwelling crustaceans, rorquals are specialized at lunge-feeding, and have a streamlined body to reduce drag while accelerating. Right whales skim-feed, meaning they use their head to effectively take in a large amount of water. Males typically mate more than one female, although the degree of polygyny varies with the species. Male strategies for reproductive success vary between performing ritual displays or lek mating, calves are typically born in the winter and spring months and females bear all the responsibility for raising them. Mothers fast for a long period of time over the period of migration. Baleen whales produce a number of vocalizations, notably the songs of the humpback whale, the meat, blubber, baleen, and oil of baleen whales have traditionally been used by the indigenous peoples of the Arctic. Once relentlessly hunted by commercial industries for these products, cetaceans are now protected by international law, however, the North Atlantic right whale is ranked critically endangered by the International Union for Conservation of Nature. Besides hunting, baleen whales also face threats from marine pollution and it has been speculated that man-made sonar results in strandings. They have rarely been kept in captivity, and this has only attempted with juveniles or members of one of the smallest species. Baleen whales are classified under the parvorder Mysticeti, and consist of four extant families, Balaenidae, Balaenopteridae, Cetotheriidae
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Minke whale
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Minke whale /ˈmɪnki/, or lesser rorqual, is a name given to two species of marine mammal belonging to a clade within the suborder of baleen whales. The minke whale was given its designation by Lacepède in 1804. The name is a translation of Norwegian minkehval, possibly after a Norwegian whaler named Meincke. Most modern classifications split the minke whale into two species, Common minke whale or northern minke whale and Antarctic minke whale or southern minke whale. Taxonomists further categorize the common minke whale into two or three subspecies, the North Atlantic minke whale, the North Pacific minke whale and dwarf minke whale. All minke whales are part of the rorquals, a family that includes the whale, the fin whale, the Brydes whale, the sei whale. The junior synonyms for B. acutorostrata are B. davidsoni, B. minimia, there is one synonym for B. bonaerensis - B. huttoni. On at least one occasion, an Antarctic minke whale has been confirmed migrating to the Arctic, in addition, at least two wild hybrids between a common minke whale and an Antarctic minke whale have been confirmed. The minke whales are the second smallest baleen whale, only the right whale is smaller. Upon reaching sexual maturity, males measure an average of 6.9 m and females 8 m in length, reported maximum lengths vary from 9.1 to 10.7 m for females and 8.8 to 9.8 m for males. Both sexes typically weigh 4–5 t at sexual maturity, and the weight may be as much as 10 t. The minke whale is a black/gray/purple color, Common minke whales are distinguished from other whales by a white band on each flipper. The body is black or dark-gray above and white underneath. Minke whales have between 240 and 360 baleen plates on each side of their mouths, most of the length of the back, including dorsal fin and blowholes, appears at once when the whale surfaces to breathe. Minke whales typically live for 30–50 years, in some cases they may live for up to 60 years, the brains of minke whales have around 12.8 billion neocortical neurons and 98.2 billion neocortical glia. The whale breathes three to five times at intervals before deep-diving for two to 20 minutes. Deep dives are preceded by a pronounced arching of the back, the maximum swimming speed of minkes has been estimated at 38 km/h. The gestation period for minke whales is 10 months, and calves measure 2.4 to 2.8 m at birth, the newborns nurse for five to 10 months
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Humpback whale
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The humpback whale is a species of baleen whale. One of the larger species, adults range in length from 12–16 m. The humpback has a body shape, with long pectoral fins. It is known for breaching and other distinctive surface behaviors, making it popular with whale watchers, males produce a complex song lasting 10 to 20 minutes, which they repeat for hours at a time. Its purpose is not clear, though it may have a role in mating, found in oceans and seas around the world, humpback whales typically migrate up to 25,000 km each year. Humpbacks feed in polar waters, and migrate to tropical or subtropical waters to breed and give birth when they fast and their diet consists mostly of krill and small fish. Humpbacks have a repertoire of feeding methods, including the bubble net technique. Like other large whales, the humpback was a target for the whaling industry, once hunted to the brink of extinction, its population fell by an estimated 90% before a 1966 moratorium. While stocks have partially recovered, entanglement in fishing gear, collisions with ships, the rorquals are believed to have diverged from the other families of the suborder Mysticeti as long ago as the middle Miocene. However, it is not known when the members of these families diverged from each other, though clearly related to the giant whales of the genus Balaenoptera, the humpback is the sole member of its genus. The humpback was first identified as de la Nouvelle Angleterre by Mathurin Jacques Brisson in his Regnum Animale of 1756. In 1781, Georg Heinrich Borowski described the species, converting Brissons name to its Latin equivalent, in 1804, Lacépède shifted the humpback from the family Balaenidae, renaming it B. jubartes. In 1846, John Edward Gray created the genus Megaptera, classifying the humpback as Megaptera longipinna, the common name is derived from the curving of their backs when diving. The generic name Megaptera from the Greek mega-/μεγα- giant and ptera/πτερα wing, the specific name means New Englander and was probably given by Brisson due to regular sightings of humpbacks off the coast of New England. Some biologists believe that these should be regarded as separate subspecies, humpbacks can easily be identified by their stocky body, obvious hump, black dorsal coloring and elongated pectoral fins. The head and lower jaw are covered with knobs called tubercles, the fluked tail, which typically rises above the surface when diving, has wavy trailing edges. Humpbacks have 270 to 400 darkly colored baleen plates on each side of their mouths, the plates measure from 18 in in the front to about 3 ft in the back, behind the hinge. Ventral grooves run from the jaw to the umbilicus, about halfway along the underside of the body
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Antarctic Circumpolar Current
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The Antarctic Circumpolar Current is an ocean current that flows clockwise from west to east around Antarctica. An alternative name for the ACC is the West Wind Drift, the ACC is the dominant circulation feature of the Southern Ocean and has a mean transport of 100-150 Sverdrups, making it the largest ocean current. More recent research puts this number at over 173 Sv. The current is due to the lack of any landmass connecting with Antarctica. Associated with the Circumpolar Current is the Antarctic Convergence, where the cold Antarctic waters meet the waters of the subantarctic. These nurture high levels of phytoplankton with associated copepods and krill, and resultant foodchains supporting fish, whales, seals, penguins, albatrosses and a wealth of other species. The clipper route, which is the fastest sailing route around the world, the current creates the Ross and Weddell gyres. The ACC connects the Atlantic, Pacific and Indian Oceans, the current is strongly constrained by landform and bathymetric features. Passing through the Indian Ocean, the current first retroflects the Agulhas Current to form the Agulhas Return Current before it is split by the Kerguelen Plateau, deflection is also seen as it passes over the mid-ocean ridge in the Southeast Pacific. The current is accompanied by three fronts, the Subantarctic front, the Polar front, and the Southern ACC front, furthermore, the waters of the Southern Ocean are separated from the warmer and saltier subtropical waters by the subtropical front. The northern boundary of the ACC is defined by the edge of the SAF. Still further south lies the PF, which is marked by a transition to cold, relatively fresh. Here a temperature minimum is allowed by salinity dominating density stratification, further south still is the SACC, which is determined as the southernmost extent of Circumpolar Deep Water. This water mass flows along the shelfbreak of the western Antarctic Peninsula and thus marks the most southerly water flowing through Drake Passage, the bulk of the transport is carried in the middle two fronts. The total transport of the ACC at Drake Passage is estimated to be around 135 Sv, or about 135 times the transport of all the worlds rivers combined. There is a small addition of flow in the Indian Ocean, with the transport south of Tasmania reaching around 147 Sv. The circumpolar current is driven by the westerly winds in the latitudes of the Southern Ocean. In latitudes where there are continents, winds blowing on light surface water can pile up light water against these continents
40.
International Standard Serial Number
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An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication. The ISSN is especially helpful in distinguishing between serials with the same title, ISSN are used in ordering, cataloging, interlibrary loans, and other practices in connection with serial literature. The ISSN system was first drafted as an International Organization for Standardization international standard in 1971, ISO subcommittee TC 46/SC9 is responsible for maintaining the standard. When a serial with the content is published in more than one media type. For example, many serials are published both in print and electronic media, the ISSN system refers to these types as print ISSN and electronic ISSN, respectively. The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers, as an integer number, it can be represented by the first seven digits. The last code digit, which may be 0-9 or an X, is a check digit. Formally, the form of the ISSN code can be expressed as follows, NNNN-NNNC where N is in the set, a digit character. The ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, for calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, the modulus 11 of the sum must be 0. There is an online ISSN checker that can validate an ISSN, ISSN codes are assigned by a network of ISSN National Centres, usually located at national libraries and coordinated by the ISSN International Centre based in Paris. The International Centre is an organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, at the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept, where ISBNs are assigned to individual books, an ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an identifier associated with a serial title. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change, separate ISSNs are needed for serials in different media. Thus, the print and electronic versions of a serial need separate ISSNs. Also, a CD-ROM version and a web version of a serial require different ISSNs since two different media are involved, however, the same ISSN can be used for different file formats of the same online serial
