1.
Indonesian language
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Indonesian is the official language of Indonesia. It is a register of Malay, an Austronesian language that has been used as a lingua franca in the multilingual Indonesian archipelago for centuries. Indonesia is the fourth most populous nation in the world, of its large population, the majority speak Indonesian, making it one of the most widely spoken languages in the world. However, most formal education, and nearly all national mass media, governance, administration, judiciary, the Indonesian name for the language is Bahasa Indonesia or sometimes simplified as Bahasa. This term is occasionally found in English and other languages. Indonesian is a register of Riau Malay, which despite its common name is not the Malay dialect native to Riau. Originally spoken in Northeast Sumatra, Malay has been used as a lingua franca in the Indonesian archipelago for half a millennium and it might be attributed to its ancestor, the Old Malay language. The Kedukan Bukit Inscription is the oldest surviving specimen of Old Malay, trade contacts carried on by various ethnic peoples at the time were the main vehicle for spreading the Old Malay language, which was the main communications medium among the traders. Ultimately, the Old Malay language became a lingua franca and was spoken widely by most people in the archipelago, Indonesian is essentially the same language as the official Malaysian, Singaporean and Brunei standards of Malay. However, it does differ from Malaysian in several respects, with differences in pronunciation and these differences are due mainly to the Dutch and Javanese influences on Indonesian. Indonesian was also influenced by the Melayu pasar, which was the lingua franca of the archipelago in colonial times, and thus indirectly by other spoken languages of the islands. Malaysian Malay claims to be closer to the classical Malay of earlier centuries, even though modern Malaysian has been influenced, in lexicon as well as in syntax. The question of whether High Malay or Low Malay was the parent of the Indonesian language is still in debate. Some linguists have argued that it was the more common Low Malay that formed the base of the Indonesian language, however, the language had never been dominant among the population of the Indonesian archipelago as it was limited to mercantile activity. The VOC adopted the Malay language as the language of their trading outpost in the east. Following the bankruptcy of the VOC the Dutch crown took control of the colony in 1799 and it was then that education in. Even then, Dutch administrators were reluctant to promote the use of Dutch compared to other colonial regimes. Dutch thus remained the language of a elite, in 1940
2.
Samosir
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For the Regency named Samosir, see Samosir Regency. Samosir, or Samosir Island, is a volcanic island in Lake Toba. Administratively, Samosir Island is governed as six of the nine districts within Samosir Regency, the lake and island were formed after the eruption of a supervolcano some 75,000 years ago. The island was connected to the surrounding caldera wall by a small isthmus. At 640 square kilometres, Samosir is the largest island within an island, and it also contains two smaller lakes, Lake Sidihoni and Lake Aek Natonang. Across the lake on the east from the island lies Uluan Peninsula, the island is linked to the mainland of Sumatra on its western part by a narrow isthmus connecting the town of Pangururan on Samosir and Tele on mainland Sumatra. Tele consequently offers one of the best views of Lake Toba, Samosir is a popular tourist destination due to its exotic history and the vistas it offers. The tourist resorts are concentrated in the Tuktuk area, the island is the centre of the Batak culture and many of the Toba Batak traditional houses remain on the island. Most of the tourist accommodations are concentrated in the town of Tuktuk. The passenger ferry leaves from Tiga Raja harbor every hour between 8.30 and 19.00, for those running late there is an option to take the passenger boat from Aji bata to Tomok until 8.30 pm. A car ferry leaves the mainland from Ajibata and lands in the town of Tomok. There are also passenger ferries and individual hotels may also have ferries available
3.
Sipisopiso
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The Sipisopiso is a plunge waterfall in the Batak highlands of Sumatra. It is formed by an underground river of the Karo plateau that hurls itself from a cave in the side of the lake Toba caldera some 120 meters down to lake level. This fact earns it the title for the highest waterfall in Indonesia, Sipisopiso is a well-known tourist attraction and a nearby vantage point offers great vistas of the fall and the lake. Sipisopiso waterfall is located in the Tanah Karo regency, at the northernmost tip of the Lake Toba caldera, the closest municipality, about 25 kilometers away, is the town of Kabanjahe
4.
North Sumatra
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North Sumatra, is a province of Indonesia. It is located on the island of Sumatra, and its capital is Medan, after independence, the first session of the National Committee of Regions, Sumatra was then divided into three sub-provinces namely North Sumatra, Central Sumatra and South Sumatra. North Sumatra province itself is an amalgamation of three regions called residency namely, Residency of Aceh, East Sumatra Residency, and residency of Tapanuli. With the publication of the Law of the Republic of Indonesia No, date 15 April 1948 subsequently determined as the anniversary of North Sumatra Province. In early 1949, the reorganization of government back in Sumatra, with the decision of the Government Emergency R. I. No.22 / Govt / Emergency Government on May 17,1949, furthermore, the Government Emergency Decree R. I. on December 17,1949, established the province of Aceh and Tapanuli Province / East Sumatra. Then, with a Government Regulation in lieu of Law No.5 Year 1950 on August 14,1950, such provisions shall be lifted and reshaped North Sumatra Province. No.24 of 1956, promulgated on December 7,1956, established an autonomous region of Aceh province, the province of North Sumatra stretches across the island of Sumatra between the Indian Ocean and the Strait Malacca. It borders Aceh province on the northwest and Riau and West Sumatra provinces in the southeast and it has an area of 72,981 km². The province contains a broad, low plain along the Strait of Malacca on which the provincial capital, Medan, is located. In the south and west, the rises to the mountain range that runs the length of Sumatra. Several large islands in the Indian Ocean off the west coast of Sumatra are currently part of North Sumatra, most notably Nias Island, there are 419 islands in propisi North Sumatra. The outer islands is the island Simuk, and the island Berhala in the Strait of Sumatra, Nias archipelago consists of the island as the main island and other smaller islands in the vicinity. Nias Islands located off the coast of western Indian Ocean, administration center located in Gunung Sitoli. Batu Islands consist of 51 islands with four islands, Sibuasi, Pini, Tanahbala. Pulautelo administrative center on the island Sibuasi, Batu Islands located in the southeast of the island of Nias. Other islands in the North Sumatra, Imanna, Pasu, Bawa, Hamutaia, Batumakalele, Lego, Masa, Bau, Simaleh, Makole, Jake, in North Sumatra, there are currently two national parks, the Gunung Leuser National Park and Batang Gadis National Park. According to the Ministerial Decree, No.44 of 2005, but this figure character is de jure alone
5.
Indonesia
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Indonesia, officially the Republic of Indonesia, is a unitary sovereign state and transcontinental country located mainly in Southeast Asia with some territories in Oceania. Situated between the Indian and Pacific oceans, it is the worlds largest island country, with more than seventeen thousand islands. At 1,904,569 square kilometres, Indonesia is the worlds 14th-largest country in terms of area and worlds 7th-largest country in terms of combined sea. It has an population of over 260 million people and is the worlds fourth most populous country. The worlds most populous island, Java, contains more than half of the countrys population, Indonesias republican form of government includes an elected legislature and president. Indonesia has 34 provinces, of which five have Special Administrative status and its capital and countrys most populous city is Jakarta, which is also the most populous city in Southeast Asia and the second in Asia. The country shares land borders with Papua New Guinea, East Timor, other neighbouring countries include Singapore, Vietnam, the Philippines, Australia, Palau, and the Indian territory of the Andaman and Nicobar Islands. Despite its large population and densely populated regions, Indonesia has vast areas of wilderness that support the second highest level of biodiversity. The country has abundant natural resources like oil and natural gas, tin, copper, agriculture mainly produces rice, palm oil, tea, coffee, cacao, medicinal plants, spices and rubber. Indonesias major trading partners are Japan, United States, China, the Indonesian archipelago has been an important region for trade since at least the 7th century, when Srivijaya and then later Majapahit traded with China and India. Local rulers gradually absorbed foreign cultural, religious and political models from the early centuries CE, Indonesian history has been influenced by foreign powers drawn to its natural resources. Indonesia consists of hundreds of native ethnic and linguistic groups. The largest – and politically dominant – ethnic group are the Javanese, a shared identity has developed, defined by a national language, ethnic diversity, religious pluralism within a Muslim-majority population, and a history of colonialism and rebellion against it. Indonesias national motto, Bhinneka Tunggal Ika, articulates the diversity that shapes the country, Indonesias economy is the worlds 16th largest by nominal GDP and the 8th largest by GDP at PPP, the largest in Southeast Asia, and is considered an emerging market and newly industrialised country. Indonesia has been a member of the United Nations since 1950, Indonesia is a member of the G20 major economies and World Trade Organization. The name Indonesia derives from the Greek name of the Indós, the name dates to the 18th century, far predating the formation of independent Indonesia. In 1850, George Windsor Earl, an English ethnologist, proposed the terms Indunesians—and, his preference, in the same publication, one of his students, James Richardson Logan, used Indonesia as a synonym for Indian Archipelago. However, Dutch academics writing in East Indies publications were reluctant to use Indonesia, they preferred Malay Archipelago, the Netherlands East Indies, popularly Indië, the East, and Insulinde
6.
Geographic coordinate system
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A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation
7.
Body of water
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A body of water or waterbody is any significant accumulation of water, generally on a planets surface. The term most often refers to oceans, seas, and lakes, a body of water does not have to be still or contained, Rivers, streams, canals, and other geographical features where water moves from one place to another are also considered bodies of water. Most are naturally occurring geographical features, but some are artificial, there are types that can be either. For example, most reservoirs are created by engineering dams, similarly, most harbors are naturally occurring bays, but some harbors have been created through construction. Bodies of water that are navigable are known as waterways, some bodies of water collect and move water, such as rivers and streams, and others primarily hold water, such as lakes and oceans. The term body of water can also refer to a reservoir of water held by a plant, note that there are some geographical features involving water that are not bodies of water, for example waterfalls, geysers and rapids. Arm of the sea - also sea arm, used to describe a sea loch, arroyo - a usually dry creek bed or gulch that temporarily fills with water after a heavy rain, or seasonally. Artificial lake or artificial pond - see reservoir or impoundment, barachois - a lagoon separated from the ocean by a sand bar. Bay - an area of water bordered by land on three sides, similar to, but smaller than a gulf, bayou - a slow-moving stream or a marshy lake. Bight - a large and often only slightly receding bay, or a bend in any geographical feature, billabong - see Oxbow lake, a pond or still body of water created when a river changes course and some water becomes trapped. Boil - see Seep Brook - a small stream, canal - an artificial waterway, usually connected to existing lakes, rivers, or oceans. Channel - the physical confine of a river, slough or ocean consisting of a bed. See also stream bed and strait, earth scientists generally use the term to describe a circular or round inlet with a narrow entrance, though colloquially the term is sometimes used to describe any sheltered bay. Basin - a region of land where water from rain or snowmelt drains downhill into another body of water, such as a river, lake, creek - an inlet of the sea, narrower than a cove. Delta - the location where a river flows into an ocean, sea, estuary, lake, distributary or distributary channel - a stream that branches off and flows away from a main stream channel. Draw - a usually dry creek bed or gulch that temporarily fills with water after a heavy rain, fjord - a submergent landform which has occurred due to glacial activity. Glacier - a large collection of ice or a river that moves slowly down a mountain. Glacial Pothole - see Kettle Gulf - a part of a lake or ocean that extends so that it is surrounded by land on three sides, similar to, but larger than a bay, headland - an area of water bordered by land on three sides
8.
Discharge (hydrology)
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In hydrology, discharge is the volume rate of water flow that is transported through a given cross-sectional area. It includes any suspended solids, dissolved chemicals, or biologic material in addition to the water itself, GH Dury and MJ Bradshaw are two hydrologists who devised the models showing the relationship between discharge and other variables in a river. The units that are used to express discharge include m³/s, ft³/s and/or acre-feet per day. For example, the discharge of the Rhine river in Europe is 2,200 cubic metres per second or 190,000,000 cubic metres per day. A commonly applied methodology for measuring, and estimating, the discharge of a river is based on a form of the continuity equation. In storm hydrology, an important consideration is the streams discharge hydrograph, the stream rises to a peak flow after each precipitation event, then falls in a slow recession. Because the peak flow also corresponds to the water level reached during the event. The amount of precipitation correlates to the volume of water that flows out of the river. The relationship between the discharge in the stream at a given cross-section and the level of the stream is described by a rating curve, average velocities and the cross-sectional area of the stream are measured for a given stream level. The velocity and the give the discharge for that level. After measurements are made for different levels, a rating table or rating curve may be developed. Once rated, the discharge in the stream may be determined by measuring the level, if a continuous level-recording device is located at a rated cross-section, the streams discharge may be continuously determined. Larger flows can transport more sediment and larger particles downstream than smaller flows due to their greater force, larger flows can also erode stream banks and damage public infrastructure
9.
Drainage basin
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A drainage basin or catchment area is any area of land where precipitation collects and drains off into a common outlet, such as into a river, bay, or other body of water. Drainage basins connect into other drainage basins at elevations in a hierarchical pattern, with smaller sub-drainage basins. Other terms used to describe drainage basins are catchment, catchment basin, drainage area, river basin and water basin. In closed drainage basins the water converges to a point inside the basin, known as a sink, which may be a permanent lake. The drainage basin acts as a funnel by collecting all the water within the covered by the basin. Each drainage basin is separated topographically from adjacent basins by a perimeter, drainage basins are similar but not identical to hydrologic units, which are drainage areas delineated so as to nest into a multi-level hierarchical drainage system. Hydrologic units are defined to allow multiple inlets, outlets, or sinks, in a strict sense, all drainage basins are hydrologic units but not all hydrologic units are drainage basins. Drainage basins of the oceans and seas of the world. Grey areas are endorheic basins that do not drain to the oceans, the following is a list of the major ocean basins, About 48. 7% of the worlds land drains to the Atlantic Ocean. The two major mediterranean seas of the world also flow to the Atlantic, The Caribbean Sea and Gulf of Mexico basin includes most of the U. S. The Mediterranean Sea basin includes much of North Africa, east-central Africa, Southern, Central, and Eastern Europe, Turkey, and the areas of Israel, Lebanon. Just over 13% of the land in the world drains to the Pacific Ocean, the Indian Oceans drainage basin also comprises about 13% of Earths land. It drains the eastern coast of Africa, the coasts of the Red Sea and the Persian Gulf, the Indian subcontinent, Burma, antarctica comprises approximately eight percent of the Earths land. The five largest river basins, from largest to smallest, are the basins of the Amazon, the Río de la Plata, the Congo, the Nile, and the Mississippi. The three rivers that drain the most water, from most to least, are the Amazon, Ganga, endorheic drainage basins are inland basins that do not drain to an ocean. Around 18% of all land drains to endorheic lakes or seas or sinks, the largest of these consists of much of the interior of Asia, which drains into the Caspian Sea, the Aral Sea, and numerous smaller lakes. Some of these, such as the Great Basin, are not single drainage basins but collections of separate, in endorheic bodies of standing water where evaporation is the primary means of water loss, the water is typically more saline than the oceans. An extreme example of this is the Dead Sea, drainage basins have been historically important for determining territorial boundaries, particularly in regions where trade by water has been important
10.
Lake
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A lake is an area of variable size filled with water, localized in a basin, that is surrounded by land, apart from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, and therefore are distinct from lagoons, Lakes can be contrasted with rivers or streams, which are usually flowing. Most lakes are fed and drained by rivers and streams, natural lakes are generally found in mountainous areas, rift zones, and areas with ongoing glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers, in some parts of the world there are many lakes because of chaotic drainage patterns left over from the last Ice Age. All lakes are temporary over geologic time scales, as they will fill in with sediments or spill out of the basin containing them. The word lake comes from Middle English lake, from Old English lacu, from Proto-Germanic *lakō, cognates include Dutch laak, Middle Low German lāke as in, de, Moorlake, de, Wolfslake, de, Butterlake, German Lache, and Icelandic lækur. Also related are the English words leak and leach, none of these definitions completely excludes ponds and all are difficult to measure. For this reason, simple size-based definitions are used to separate ponds. One definition of lake is a body of water of 2 hectares or more in area, however, others have defined lakes as waterbodies of 5 hectares and above, or 8 hectares and above. Charles Elton, one of the founders of ecology, regarded lakes as waterbodies of 40 hectares or more. The term lake is used to describe a feature such as Lake Eyre. In common usage, many bear names ending with the word pond. One textbook illustrates this point with the following, In Newfoundland, for example, almost every lake is called a pond, whereas in Wisconsin, the majority of lakes on Earth are fresh water, and most lie in the Northern Hemisphere at higher latitudes. Canada, with a drainage system has an estimated 31,752 lakes larger than 3 square kilometres and an unknown total number of lakes. Finland has 187,888 lakes 500 square metres or larger, most lakes have at least one natural outflow in the form of a river or stream, which maintain a lakes average level by allowing the drainage of excess water. Some lakes do not have an outflow and lose water solely by evaporation or underground seepage or both. Many lakes are artificial and are constructed for power generation, aesthetic purposes, recreational purposes, industrial use. Globally, lakes are greatly outnumbered by ponds, of an estimated 304 million standing water bodies worldwide, 91% are 1 hectare or less in area
11.
Caldera
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A caldera is a large cauldron-like depression that forms following the evacuation of a magma chamber/reservoir. When large volumes of magma are erupted over a time period. The ground surface then collapses downward into the emptied magma chamber. Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence, only seven known caldera-forming collapses have occurred since the start of the 20th century, most recently at Bárðarbunga volcano in Iceland. The word comes from Spanish caldera, and this from Latin caldaria, in some texts the English term cauldron is also used. If enough magma is ejected, the chamber is unable to support the weight of the volcanic edifice above it. A roughly circular fracture, the fault, develops around the edge of the chamber. Ring fractures serve as feeders for fault intrusions which are known as ring dykes. Secondary volcanic vents may form above the ring fracture, as the magma chamber empties, the center of the volcano within the ring fracture begins to collapse. The collapse may occur as the result of a cataclysmic eruption. The total area that collapses may be hundreds or thousands of square kilometers, some calderas are known to host rich ore deposits. One of the worlds best-preserved mineralized calderas is the Sturgeon Lake Caldera in northwestern Ontario, Canada, if the magma is rich in silica, the caldera is often filled in with ignimbrite, tuff, rhyolite, and other igneous rocks. Silica-rich magma has a high viscosity, and therefore does not flow easily like basalt, as a result, gases tend to become trapped at high pressure within the magma. Further lava flows may be erupted, if volcanic activity continues, the center of the caldera may be uplifted in the form of a resurgent dome such as is seen at Cerro Galán, Lake Toba, Yellowstone, etc. by subsequent intrusion of magma. A silicic or rhyolitic caldera may erupt hundreds or even thousands of kilometers of material in a single event. Even small caldera-forming eruptions, such as Krakatoa in 1883 or Mount Pinatubo in 1991, may result in significant local destruction, large calderas may have even greater effects. When Yellowstone Caldera last erupted some 650,000 years ago, it released about 1,000 km3 of material, by comparison, when Mount St. Helens erupted in 1980, it released ~1.2 km3 of ejecta. The ecological effects of the eruption of a large caldera can be seen in the record of the Lake Toba eruption in Indonesia, more recently several geneticists, including Lynn Jorde and Henry Harpending have proposed that the human species was reduced to approximately five to ten thousand people
12.
Supervolcano
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A supervolcano is a volcano capable of producing a volcanic eruption with an ejecta mass greater than 1015 kg. This can occur at hotspots or at subduction zones, the Oruanui eruption of New Zealands Taupo Volcano, the worlds most recent supereruption, had a Volcanic Explosivity Index of 8. The origin of the term supervolcano is linked to an early 20th-century scientific debate about the geological history, in 1925, Edwin T. Hodge suggested that a very large volcano, which he named Mount Multnomah, had existed in that region. He believed that several peaks in the Three Sisters area are the left after Mount Multnomah had been largely destroyed by violent volcanic explosions. In 1948, the existence of Mount Multnomah was ignored by volcanologist Howel Williams in his book The Ancient Volcanoes of Oregon. The book was reviewed in 1949 by another volcanologist, F. M. Byers Jr, in the review, Byers refers to Mount Multnomah as a supervolcano. Volcanologists and geologists do not refer to supervolcanoes in their scientific work, since about 2000, however, the term has been used by professionals for communicating science to the public. The term megacaldera is sometimes used for caldera supervolcanoes, such as the Blake River Megacaldera Complex in the Abitibi greenstone belt of Ontario and Quebec, eruptions that rate VEI8 are termed super eruptions. Large igneous provinces such as Iceland, the Siberian Traps, Deccan Traps, when created, these regions often occupy several thousand square kilometres and have volumes on the order of millions of cubic kilometers. In most cases, the lavas are laid down over several million years. They release large amounts of gases, the Réunion hotspot produced the Deccan Traps about 66 million years ago, coincident with the Cretaceous–Paleogene extinction event. Such outpourings are not explosive, though lava fountains may occur, many volcanologists consider that Iceland may be a LIP that is currently being formed. The last major outpouring occurred in 1783–84 from the Laki fissure which is approximately 40 km long, an estimated 14 km3 of basaltic lava was poured out during the eruption. The Ontong Java Plateau now has an area of about 2,000,000 km2, Volcanic eruptions are classified using the Volcanic Explosivity Index, or VEI. It is a scale, which means that an increase of one in VEI number is equivalent to a tenfold increase in volume of erupted material. VEI8 eruptions are colossal events that throw out at least 1,000 km3 bulk volume, VEI7 events eject bulk volume at least 100 km3. VEI6 eruptions occurred at Krakatoa in 1883 and Mount Pinatubo in 1991 and these eruptions ejected ~10 and 25 km3 bulk volume, respectively. At Krakatoa, the Dutch colonial authorities claimed that the toll was 36,417
13.
Island
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An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, an island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. A grouping of geographically or geologically related islands is called an archipelago, an island may be described as such, despite the presence of an artificial land bridge. Example, Singapore and its causeway, or the various Dutch delta islands, there are two main types of islands in the sea, continental and oceanic. The word island derives from Middle English iland, from Old English igland, Old English ieg is actually a cognate of Swedish ö and German Aue, and related to Latin aqua. There is a difference between islands and continents in terms of geology, continents sit on continental lithosphere which is part of tectonic plates floating high on Earths mantle. Oceanic crust is also part of tectonic plates, but it is denser than continental lithosphere, Islands are either extensions of the oceanic crust or geologically they are part of some continent sitting on continental lithosphere. This holds true for Australia, which sits on its own continental lithosphere, continental islands are bodies of land that lie on the continental shelf of a continent. A special type of island is the microcontinental island, which is created when a continent is rifted. Examples are Madagascar and Socotra off Africa, the Kerguelen Islands, New Caledonia, New Zealand, another subtype is an island or bar formed by deposition of tiny rocks where water current loses some of its carrying capacity. While some are transitory and may disappear if the volume or speed of the current changes, others are stable, oceanic islands are islands that do not sit on continental shelves. The vast majority are volcanic in origin, such as Saint Helena in the South Atlantic Ocean, the few oceanic islands that are not volcanic are tectonic in origin and arise where plate movements have lifted up the ocean floor above the surface. Examples are Saint Peter and Paul Rocks in the Atlantic Ocean, one type of volcanic oceanic island is found in a volcanic island arc. These islands arise from volcanoes where the subduction of one plate under another is occurring, examples are the Aleutian Islands, the Mariana Islands, and most of Tonga in the Pacific Ocean. The only examples in the Atlantic Ocean are some of the Lesser Antilles, another type of volcanic oceanic island occurs where an oceanic rift reaches the surface. There are two examples, Iceland, which is the second largest volcanic island, and Jan Mayen. A third type of oceanic island is formed over volcanic hotspots. A hotspot is more or less stationary relative to the tectonic plate above it
14.
Sumatra
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Sumatra is a large island in western Indonesia that is part of the Sunda Islands. It is the largest island that is entirely in Indonesia and the sixth-largest island in the world at 473,481 km2, Sumatra is an elongated landmass spanning a diagonal northwest-southeast axis. The Indian Ocean borders the west, northwest, and southwest sides of Sumatra with the chain of Simeulue, Nias. On the northeast side the narrow Strait of Malacca separates the island from the Malay Peninsula, on the southeast the narrow Sunda Strait separates Sumatra from Java. The northern tip of Sumatra borders the Andaman Islands, while on the eastern side are the islands of Bangka and Belitung, Karimata Strait. The Bukit Barisan mountains, which several active volcanoes, form the backbone of the island, while the northeast sides are outlying lowlands with swamps, mangrove. The equator crosses the island at its center on West Sumatra, the climate of the island is tropical, hot and humid with lush tropical rain forest once dominating the landscape. Sumatra was known in ancient times by the Sanskrit names of Swarnadwīpa and Swarnabhūmi, the first word mentioning the name of Sumatra was the name of Srivijayan Haji Sumatrabhumi, who sent an envoy to China in 1017. Arab geographers referred to the island as Lamri in the tenth through thirteenth centuries, late in the 14th century the name Sumatra became popular in reference to the kingdom of Samudra Pasai, which was a rising power until it was replaced by Sultanate of Aceh. Sultan Alauddin Shah of Aceh, on letters written in 1602 addressed to Queen Elizabeth I of England, referred to himself as king of Aceh, the word itself is from Sanskrit Samudra, meaning gathering together of waters, sea or ocean. European writers in the 19th century found that the inhabitants did not have a name for the island. The Melayu Kingdom was absorbed by Srivijaya, Srivijaya was a Buddhist monarchy centred in what is now Palembang. Dominating the region trade and conquest throughout the 7th to 9th centuries. The empire was a thalassocracy or maritime power that extended its influence from island to island, Palembang was a center for scholarly learning, and it was there the Chinese Buddhist pilgrim I Ching studied Sanskrit in 671 CE before departing for India. On his journey to China, he spent four years in Palembang translating Buddhist texts, Srivijayan influence waned in the 11th century after it was defeated by the Chola Empire of southern India. At the same time, Islam made its way to Sumatra through Arabs, by the late 13th century, the monarch of the Samudra kingdom had converted to Islam. Marco Polo visited the island in 1292, and Ibn Battuta visited twice during 1345–1346, Samudra was succeeded by the powerful Aceh Sultanate, which survived to the 20th century. With the coming of the Dutch, the many Sumatran princely states fell under their control
15.
Crater lake
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Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not made. Crater lakes covering active volcanic vents are known as volcanic lakes, and the water within them is often acidic, saturated with volcanic gases. For example, the lake of Kawah Ijen in Indonesia has a pH of under 0.5. Lakes located in dormant or extinct volcanoes tend to have water. Crater lakes form as the depression, within the crater rim, is filled by water. The water may come from precipitation, groundwater circulation or melted ice and its level rises until an equilibrium is reached between the rates of incoming and outgoing water. Sources of water loss singly or together may include evaporation, subsurface seepage, if the volcanic dam portion erodes rapidly or fails catastrophically, the occurrence produces a breakout or outburst flood. With changes in environmental conditions over time, the occurrence of floods is common to all natural dam types. A well-known crater lake, which bears the name as the geological feature, is Crater Lake in Oregon. It is located in the caldera of Mount Mazama and it is the deepest lake in the United States with a depth of 594 m. Crater Lake is fed solely by falling rain and snow, with no inflow or outflow at the surface, and hence is one of the clearest lakes in the world. The highest volcano in the world,6, 893-m Ojos del Salado in Chile, has a permanent crater lake about 100 m in diameter at an elevation of 6,390 m on its eastern side. This is most likely the highest lake of any kind in the world, due to their unstable environments, some crater lakes exist only intermittently. Hence, making Lake Toba the largest crater lake in the world, while many crater lakes are picturesque, they can also be deadly. Gas discharges from Lake Nyos suffocated 1,800 people in 1986, example of such impact crater lakes include Manicouagan in Canada, Lake Bosumtwi in Ghana and Siljan in Sweden. More rarely they can also fill craters caused by artificial explosions, lava lake Volcanic crater Caldera Types of volcanic eruptions Maar Atoll Impact crater Delmelle, Pierre, Bernard, Alain. Journal of Volcanology and Geothermal Research, kusakabe, Minoru, ed. Geochemistry of Crater Lakes. California Davis Crater Lake National Park documentation in Building Oregon, Architecture of Oregon & the Pacific Northwest archive World Volcanic Lakes Map
16.
Earth
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Earth, otherwise known as the World, or the Globe, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets, according to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earths gravity interacts with objects in space, especially the Sun. During one orbit around the Sun, Earth rotates about its axis over 365 times, thus, Earths axis of rotation is tilted, producing seasonal variations on the planets surface. The gravitational interaction between the Earth and Moon causes ocean tides, stabilizes the Earths orientation on its axis, Earths lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earths surface is covered with water, mostly by its oceans, the remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earths polar regions are covered in ice, including the Antarctic ice sheet, Earths interior remains active with a solid iron inner core, a liquid outer core that generates the Earths magnetic field, and a convecting mantle that drives plate tectonics. Within the first billion years of Earths history, life appeared in the oceans and began to affect the Earths atmosphere and surface, some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earths distance from the Sun, physical properties, in the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely, over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humans have developed diverse societies and cultures, politically, the world has about 200 sovereign states, the modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most often spelled eorðe. It has cognates in every Germanic language, and their proto-Germanic root has been reconstructed as *erþō, originally, earth was written in lowercase, and from early Middle English, its definite sense as the globe was expressed as the earth. By early Modern English, many nouns were capitalized, and the became the Earth. More recently, the name is simply given as Earth. House styles now vary, Oxford spelling recognizes the lowercase form as the most common, another convention capitalizes Earth when appearing as a name but writes it in lowercase when preceded by the. It almost always appears in lowercase in colloquial expressions such as what on earth are you doing, the oldest material found in the Solar System is dated to 4. 5672±0.0006 billion years ago. By 4. 54±0.04 Gya the primordial Earth had formed, the formation and evolution of Solar System bodies occurred along with the Sun
17.
Toba catastrophe theory
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The Toba supereruption was a supervolcanic eruption that occurred about 75,000 years ago at the site of present-day Lake Toba. It is one of the Earths largest known eruptions, the Toba catastrophe theory holds that this event caused a global volcanic winter of 6–10 years and possibly a 1, 000-year-long cooling episode. In 1998, the theory was further developed by Stanley H. Ambrose of the University of Illinois at Urbana-Champaign. Both the link and global winter theories are highly controversial, the Toba event is the most closely studied supereruption. The Toba eruption or Toba event occurred at the present location of Lake Toba, in Indonesia and this eruption was the last and largest of four eruptions of Toba during the Quaternary period, and is also recognized from its diagnostic horizon of ashfall, the youngest Toba tuff. It had a volcanic explosivity index of 8, it made a sizable contribution to the 100×30 km caldera complex. Tobas erupted mass deposited an ash layer about 15 centimetres thick over the whole of South Asia, a blanket of volcanic ash was also deposited over the Indian Ocean, and the Arabian Sea and South China Sea. The Toba eruption apparently coincided with the onset of the last glacial period, evidence from Greenland ice cores indicates a 1, 000-year period of low δ18O and increased dust deposition immediately following the eruption. The eruption may have caused this 1, 000-year period of cooler temperatures, according to Alan Robock, who has also published nuclear winter papers, the Toba eruption did not precipitate the last glacial period. Because the saturated adiabatic lapse rate is 4.9 °C/1,000 m for temperatures above freezing, the tree line and the snow line were around 3,000 m lower at this time. The climate recovered over a few decades, and Robock found no evidence that the 1, in contrast, Oppenheimer believes that estimates of a drop in surface temperature by 3–5 °C are probably too high, and he suggests that temperatures dropped only by 1 °C. Robock has criticized Oppenheimers analysis, arguing that it is based on simplistic T-forcing relationships and they concluded that the largest known volcanic eruption in the history of the human species did not significantly alter the climate of East Africa, attracting criticism from Richard Roberts. Lane explained, We examined smear slides at a 2-mm interval, corresponding to subdecadal resolution and we observed no obvious change in sediment composition or Fe/Ti ratio, suggesting that no thermally driven overturn of the water column occurred following the Toba supereruption. In 2015, a new study of climate of East Africa supported Lanes conclusion, according to the genetic bottleneck theory, between 50,000 and 100,000 years ago, human populations sharply decreased to 3, 000–10,000 surviving individuals. It is supported by genetic evidence suggesting that humans are descended from a very small population of between 1,000 and 10,000 breeding pairs that existed about 70,000 years ago. For example, a 10-year volcanic winter triggered by the eruption could have destroyed the food sources of humans. Τhese environmental changes may have generated population bottlenecks in many species, including hominids, therefore, the genetic differences among modern humans may reflect changes within the last 70,000 years, rather than gradual differentiation over hundreds of thousands of years. Other research has cast doubt on a link between Toba and a genetic bottleneck and this has been challenged by evidence for the presence of Neanderthals in Europe and Homo floresiensis in Southeastern Asia who survived the eruption by 50,000 and 60,000 years, respectively
18.
Population bottleneck
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A population bottleneck is a sharp reduction in the size of a population due to environmental events or human activities. Genetic diversity remains lower, only slowly increasing with time as random mutations occur and this genetic drift can change the proportional distribution of an allele by chance and even lead to fixation or loss of alleles. Due to the population size after a bottleneck event, the chance of inbreeding and genetic homogeneity increases. Population bottlenecks play an important role in biology and in the context of agriculture. That said, the possibility of a severe recent species-wide bottleneck can be ruled out, parallel bottlenecks were proposed to exist among chimpanzees, gorillas, rhesus macaques, orangutans and tigers. The hypothesis was based on evidence of sudden climate change and on coalescence evidence of some genes. However, subsequent research, especially in the 2010s, appeared to both the climate argument and the genetic argument. Recent research shows the extent of change was much smaller than believed by proponents of the theory. In addition, coalescence times for Y-chromosomal and mitochondrial DNA have been revised to well above 100,000 years since 2011, genetic material inherited exclusively from either father or mother can be traced back in time via either matrilineal or patrilineal ancestry. In 2000, a Molecular Biology and Evolution paper suggested a model or a long bottleneck to account for the limited genetic variation. European bison, also called wisent, faced extinction in the early 20th century, the animals living today are all descended from 12 individuals and they have extremely low genetic variation, which may be beginning to affect the reproductive ability of bulls. The population of American bison fell due to overhunting, nearly leading to extinction around the year 1890, a classic example of a population bottleneck is that of the northern elephant seal, whose population fell to about 30 in the 1890s. Although it now numbers in the hundreds of thousands, the potential for bottlenecks within colonies remains, dominant bulls are able to mate with the largest number of females — sometimes as many as 100. With so much of a colonys offspring descended from just one dominant male, genetic diversity is limited, making the more vulnerable to diseases. The genome of the giant panda shows evidence of a bottleneck that took place about 43,000 years ago. There is also evidence of at least one species, the golden snub-nosed monkey. Further deductions can sometimes be inferred from a population bottleneck. DNA analyses date the bottleneck to around 88,000 years before present, about 100,000 YBP the volcano erupted violently, burying much of the tortoise habitat deep in pumice and ash
19.
Volcanic winter
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Volcanic stratospheric aerosols cool the surface by reflecting solar radiation and warm the stratosphere by absorbing terrestrial radiation. The volcanic aerosols, resulting from the 1991 Pinatubo eruption and others, have shown to contribute to anthropogenic ozone depletion. The variations in atmospheric warming and cooling results in changes in tropospheric and stratospheric circulation, the effects of volcanic eruptions on recent winters are modest in scale, but historically have been significant. Most recently, the 1991 explosion of Mount Pinatubo, a stratovolcano in the Philippines, in 1883, the explosion of Krakatoa created volcanic winter-like conditions. The four years following the explosion were unusually cold, and the winter of 1887-1888 included powerful blizzards, northern hemisphere temperatures dropped by about 1 °C in the year following the Laki eruption. However Franklins proposal has been questioned, in 1600, the Huaynaputina in Peru erupted. Tree ring studies show that 1601 was cold, russia had its worst famine in 1601-1603. From 1600 to 1602, Switzerland, Latvia and Estonia had exceptionally cold winters, the wine harvest was late in 1601 in France, and in Peru and Germany, wine production collapsed. Peach trees bloomed late in China, and Lake Suwa in Japan froze early, in 1452 or 1453, a cataclysmic eruption of the submarine volcano Kuwae caused worldwide disruptions. The Great Famine of 1315–1317 in Europe may have been precipitated by an event, perhaps that of Mount Tarawera, New Zealand. The extreme weather events of 535–536 are most likely linked to a volcanic eruption, the latest theorised explanation is the Tierra Blanca Joven eruption of the Ilopango caldera in central El Salvador. One proposed volcanic winter occurred around 71, 000–73,000 years ago following the supereruption of Lake Toba on Sumatra island in Indonesia, others argue that the climatic effects of the eruption were too weak and brief to impact early human populations to the degree proposed. This, combined with the occurrence of most human differentiations in that same period, is a probable case of bottleneck linked to volcanic winters. On average, super-eruptions with total eruptive masses of at least 1015 kg occur every 1 million years and this result led the archaeologists to conclude that the largest known volcanic eruption in the history of the human species did not significantly alter the climate of East Africa. Such events may diminish populations to levels low enough for evolutionary changes, with the Toba bottleneck, many species show massive effects of narrowing of the gene pool, and Toba reduced the human population to between 15,000 and 40,000 or even fewer. Global dimming Impact winter Nuclear winter Supervolcano Timeline of volcanism on Earth Year Without a Summer MR Rampino, annual Review of Earth and Planetary Sciences. Limited global change due to the largest known Quaternary eruption, Toba ~~74 Kyr BP
20.
Lake Malawi
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It is the ninth largest lake in the world and the third largest and second deepest lake in Africa. It is home to species of fish than any other lake. The Mozambique portion of the lake was declared a reserve by the Government of Mozambique on June 10,2011. Lake Malawi is a lake, meaning that its water layers do not mix. The permanent stratification of Lake Malawis water and the boundary are maintained by moderately small chemical and thermal gradients. Lake Malawi is between 560 kilometres and 580 kilometres long, and about 75 kilometres wide at its widest point, the total surface area of the lake is about 29,600 square kilometres. The lake has shorelines on western Mozambique, eastern Malawi, the largest river flowing into it is the Ruhuhu River, and there is an outlet at its southern end, the Shire River, a tributary that flows into the very large Zambezi River in Mozambique. The lake lies in a formed by the opening of the East African Rift. This is called a divergent plate tectonics boundary and it is variously estimated at about 40,000 years old or about one to two million years. The lake is about 350 kilometres southeast of Lake Tanganyika, another of the lakes of the East African Rift. The Lake Malawi National Park is located at the end of the lake. The lakes water is alkaline and warm with a temperature between 24 and 29 °C, while deep sections typically are about 22 °C. The oxygen limit is at a depth of approximately 250 m, effectively restricting fish, the Portuguese trader Candido José da Costa Cardoso was the first European to visit the lake in 1846. David Livingstone reached the lake in 1859, and named it Lake Nyasa, rhoadess crew found the Hermann von Wissmann in a bay near Sphinxhaven, in German East African territorial waters. Gwendolen disabled the German boat with a cannon shot from a range of about 1,800 metres. This very brief gunboat conflict was hailed by The Times in England as the British Empires first naval victory of World War I, the Lake of Stars is the nickname for Lake Malawi coined by David Livingstone. This name came about due to lights from the lanterns of the fishermen in Malawi on their boats, the lake is also known as the Lake of Storms, for the unpredictable and extremely violent gales that sweep through the area. The partition of the surface area between Malawi and Tanzania is under dispute
21.
Quaternary
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Quaternary is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy. It follows the Neogene Period and spans from 2.588 ±0.005 million years ago to the present, the Quaternary Period is divided into two epochs, the Pleistocene and the Holocene. The informal term Late Quaternary refers to the past 0. 5–1.0 million years, the Quaternary Period is typically defined by the cyclic growth and decay of continental ice sheets driven by Milankovitch cycles and the associated climate and environmental changes that occurred. The term Quaternary was proposed by Giovanni Arduino in 1759 for alluvial deposits in the Po River valley in northern Italy and it was introduced by Jules Desnoyers in 1829 for sediments of Frances Seine Basin that seemed clearly to be younger than Tertiary Period rocks. The Quaternary Period follows the Neogene Period and extends to the present, the Quaternary covers the time span of glaciations classified as the Pleistocene, and includes the present interglacial time-period, the Holocene. This places the start of the Quaternary at the onset of Northern Hemisphere glaciation approximately 2.6 million years ago, Quaternary stratigraphers usually worked with regional subdivisions. From the 1970s, the International Commission on Stratigraphy tried to make a single geologic time scale based on GSSPs, the Quaternary subdivisions were defined based on biostratigraphy instead of paleoclimate. This led to the problem that the base of the Pleistocene was at 1.805 Mya. The ICS then proposed to use of the name Quaternary altogether. The Anthropocene has been proposed as an epoch as a mark of the anthropogenic impact on the global environment starting with the Industrial Revolution. The Anthropocene is not officially designated by the ICS, however, the 2.6 million years of the Quaternary represents the time during which recognizable humans existed. Over this short period, there has been relatively little change in the distribution of the continents due to plate tectonics. The Quaternary geological record is preserved in detail than that for earlier periods. The climate was one of periodic glaciations with continental glaciers moving as far from the poles as 40 degrees latitude, there was a major extinction of large mammals in Northern areas at the end of the Pleistocene Epoch. Many forms such as saber-toothed cats, mammoths, mastodons, glyptodonts, others, including horses, camels and American cheetahs became extinct in North America. Glaciation took place repeatedly during the Quaternary Ice Age – a term coined by Schimper in 1839 that began with the start of the Quaternary about 2.58 Mya and continues to the present-day. In 1821, a Swiss engineer, Ignaz Venetz, presented an article in which he suggested the presence of traces of the passage of a glacier at a distance from the Alps. This idea was initially disputed by another Swiss scientist, Louis Agassiz, a year later, Agassiz raised the hypothesis of a great glacial period that would have had long-reaching general effects
22.
Tuff
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Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is compacted into a rock in a process called consolidation. Tuff is sometimes called tufa, particularly used as construction material. Rock that contains greater than 50% tuff is considered tuffaceous, Tuff is a relatively soft rock, so it has been used for construction since ancient times. Since it is common in Italy the Romans used it often for construction, the Rapa Nui people used it to make most of the moai statues in Easter Island. Tuff can be classified as either sedimentary or igneous rocks and they are usually studied in the context of igneous petrology, although they are sometimes described using sedimentological terms. The material that is expelled in a volcanic eruption can be classified into three types, Volcanic gases, a mixture mostly of water vapour, carbon dioxide. Lava, the name of magma when it emerges and flows over the surface, and tephra, chunks of solid material of all shapes and sizes ejected and thrown through the air. Tephra is made when magma inside the volcano is blown apart by the expansion of hot volcanic gases. It is common for magma to explode as the gas dissolved in it comes out of solution as the pressure decreases when it flows to the surface and these violent explosions produce solid chunks of material that can then fly from the volcano. When these chunks are smaller than 2 mm in diameter they are called volcanic ash and it is made of small, slaggy pieces of lava and rock that have been tossed into the air by outbursts of steam and other gases. Among the loose beds of ash that cover the slopes of many volcanoes, in addition to true ashes of the kind described above, there are lumps of the old lavas and tuffs forming the walls of the crater, etc. In some great volcanic explosions nothing but materials of the kind were emitted. The ashes vary in size from large blocks twenty feet or more in diameter to the minutest impalpable dust, the large masses are called volcanic bombs, they have mostly a rounded, elliptical or pear-shaped form owing to rotation in the air before they solidified. Many of them have ribbed or nodular surfaces, and sometimes they have a crust intersected by many cracks like the surface of a loaf of bread, any ash in which they are very abundant is called an agglomerate. But many volcanoes stand near the sea, and the ashes cast out by them are mingled with the sediments that are gathering at the bottom of the waters, in this way ashy muds or sands or even in some cases ashy limestones are being formed. As a matter of fact most of the found in the older formations contain admixtures of clay, sand, and sometimes fossil shells. The showers of ashes often follow one another after longer or shorter intervals, the coarsest materials or agglomerates show this least distinctly, in the fine beds it is often developed in great perfection
23.
Graben
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In geology, a graben is a depressed block of the Earths crust bordered by parallel faults. Graben is German for ditch or trench, the plural form is either graben or grabens. A graben is a valley with an escarpment on each side caused by the displacement of a block of land downward. Graben often occur side-by-side with horsts, horst and graben structures indicate tensional forces and crustal stretching. Graben are produced from parallel normal faults, where the displacement of the wall is downward. The faults typically dip toward the center of the graben from both sides, horsts are parallel blocks that remain between graben, the bounding faults of a horst typically dip away from the center line of the horst. Single or multiple graben can produce a rift valley, in many rifts, the graben are asymmetric, with a major fault along only one of the boundaries, and these are known as half-graben. The polarity of the bounding faults typically alternates along the length of the rift. The asymmetry of a half-graben strongly affects syntectonic deposition, comparatively little sediment enters the half-graben across the main bounding fault because of footwall uplift on the drainage systems. The exception is at any offset in the bounding fault. Most of the sediment will enter the half-graben down the hanging wall side. S. Central Graben, North Sea Viking Graben, North Sea Fossa
24.
Stratovolcano
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A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a profile and periodic explosive eruptions and effusive eruptions. The lava flowing from stratovolcanoes typically cools and hardens before spreading far due to high viscosity, the magma forming this lava is often felsic, having high-to-intermediate levels of silica, with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as 15 km, stratovolcanoes are sometimes called composite volcanoes because of their composite layered structure built up from sequential outpourings of eruptive materials. They are among the most common types of volcanoes, in contrast to the less common shield volcanoes, two famous stratovolcanoes are Krakatoa, best known for its catastrophic eruption in 1883 and Vesuvius, famous for its destruction of the towns Pompeii and Herculaneum in 79 CE. Both eruptions claimed thousands of lives, in modern times, Mount Saint Helens and Mount Pinatubo have erupted catastrophically. Existence of stratovolcanoes has not been proved on other bodies of the solar system with one exception. Their existence was suggested for some isolated massifs on Mars, e. g. Zephyria Tholus, stratovolcanoes are common at subduction zones, forming chains along plate tectonic boundaries where oceanic crust is drawn under continental crust or another oceanic plate. The release of water from hydrated minerals is termed dewatering, and occurs at pressures and temperatures for each mineral. The magma then rises through the crust, incorporating silica-rich crustal rock, when the magma nears the top surface, it pools in a magma chamber under or within the volcano. There, the low pressure allows water and other volatiles dissolved in the magma to escape from solution, as occurs when a bottle of carbonated water is opened. Once a critical volume of magma and gas accumulates, the obstacle of the cone is overcome. In recorded history, explosive eruptions at subduction zone volcanoes have posed the greatest hazard to civilizations. Subduction-zone stratovolcanoes, such as Mount St. Helens, Mount Etna and Mount Pinatubo, typically erupt with explosive force, as a consequence, the tremendous internal pressures of the trapped volcanic gases remain in the pasty magma. Following the breaching of the chamber, the magma degasses explosively. The gases and water out with speed and force. Since 1600 CE, nearly 300,000 people have killed by volcanic eruptions. Most deaths were caused by flows and mudflows, deadly hazards that often accompany explosive eruptions of subduction-zone stratovolcanoes
25.
Fumarole
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A fumarole is an opening in a planets crust, often in areas surrounding volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrogen chloride, and hydrogen sulfide. The steam forms when superheated water vaporizes as its pressure drops when it emerges from the ground, the name solfatara, from the Italian solfo, sulfur, is given to fumaroles that emit sulfurous gases. Fumaroles may occur along tiny cracks or long fissures, in clusters or fields. A fumarole field is an area of springs and gas vents where magma or hot igneous rocks at shallow depth release gases or interact with groundwater. From the perspective of groundwater, a fumarole could be described as a hot spring that boils off all its water before the water reaches the surface. Fumaroles may persist for decades or centuries if located above a persistent heat source, the Valley of Ten Thousand Smokes, for example, was formed during the 1912 eruption of Novarupta in Alaska. Initially, thousands of fumaroles occurred in the ash from the eruption. An estimated four thousand fumaroles exist within the boundaries of Yellowstone National Park in the United States, in April 2006 fumarole emissions killed three ski-patrol workers east of Chair 3 at Mammoth Mountain Ski Area in California. The workers were overpowered by toxic fumes that had accumulated in a crevasse they had fallen into, another example is an array of fumaroles in the Valley of Desolation in Morne Trois Pitons National Park in Dominica. Boiling Lake Mazuku Mofetta Mudpot Mud volcano USGS Photo Glossary, Fumarole Sulfur Mining on Gunung Welirang Volcano Chisholm, Hugh, ed. Fumarole
26.
Types of volcanic eruptions
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Several types of volcanic eruptions—during which lava, tephra, and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed, some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series. There are three different types of eruptions, the most well-observed are magmatic eruptions, which involve the decompression of gas within magma that propels it forward. Phreatomagmatic eruptions are another type of eruption, driven by the compression of gas within magma. Within these wide-defining eruptive types are several subtypes, the weakest are Hawaiian and submarine, then Strombolian, followed by Vulcanian and Surtseyan. The stronger eruptive types are Pelean eruptions, followed by Plinian eruptions, subglacial and phreatic eruptions are defined by their eruptive mechanism, and vary in strength. An important measure of strength is Volcanic Explosivity Index, an order of magnitude scale ranging from 0 to 8 that often correlates to eruptive types. Explosive eruptions are characterized by gas-driven explosions that propels magma and tephra, effusive eruptions, meanwhile, are characterized by the outpouring of lava without significant explosive eruption. Volcanic eruptions vary widely in strength, on the one extreme there are effusive Hawaiian eruptions, which are characterized by lava fountains and fluid lava flows, which are typically not very dangerous. On the other extreme, Plinian eruptions are large, violent, volcanoes are not bound to one eruptive style, and frequently display many different types, both passive and explosive, even the span of a single eruptive cycle. Volcanoes do not always erupt vertically from a crater near their peak. Some volcanoes exhibit lateral and fissure eruptions, notably, many Hawaiian eruptions start from rift zones, and some of the strongest Surtseyan eruptions develop along fracture zones. Scientists believed that pulses of magma mixed together in the chamber before climbing upward—a process estimated to several thousands of years. But Columbia University volcanologists found that the eruption of Costa Rica’s Irazú Volcano in 1963 was likely triggered by magma that took a route from the mantle over just a few months. The volcanic explosivity index is a scale, from 0 to 8 and it is used by the Smithsonian Institutions Global Volcanism Program in assessing the impact of historic and prehistoric lava flows. It operates in a way similar to the Richter scale for earthquakes, the vast majority of volcanic eruptions are of VEIs between 0 and 2. Volcanic eruptions by VEI index Magmatic eruptions produce juvenile clasts during explosive decompression from gas release, Hawaiian eruptions are a type of volcanic eruption, named after the Hawaiian volcanoes with which this eruptive type is hallmark. Hawaiian eruptions are the calmest types of events, characterized by the effusive eruption of very fluid basalt-type lavas with low gaseous content
27.
William I. Rose
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Rose is a professor of mineralogy, petrology and meteorology at Michigan Technological University. He was involved in a study of Lake Toba on Sumatra and he won the 2002 N. L. Bowen Award
28.
Michigan Technological University
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Michigan Technological University is a public research university located in Houghton, Michigan, United States. Its main campus sits on 925 acres on a bluff overlooking Portage Lake, Michigan Tech was founded in 1885 as the first post-secondary institution in the Upper Peninsula of Michigan, and was created to train mining engineers to operate the local copper mines. Science, technology, forestry and business have been added to the engineering disciplines. US News and World Report ranked Michigan Techs undergraduate program 116th in the based on peer assessment, student selectivity, financial resources. Michigan Tech was also rated among the Best in the Midwest by The Princeton Review, Michigan Techs athletic teams are nicknamed the Huskies and compete primarily in the NCAA Division II Great Lakes Intercollegiate Athletic Conference. The mens hockey team competes in Division I as a member of the Western Collegiate Hockey Association, the womens basketball team were national runners-up in 2011. Michigan Tech was founded in 1885 as the Michigan Mining School, after much agitation by Jay Abel Hubbell, the state legislature established the school to train mining engineers. Hubbell donated land for the schools first buildings, the school started with four faculty members and twenty-three students. It was housed in the Houghton Fire Hall from 1886 through 1889, a few years after the schools creation, enrollment grew to such a point that its name no longer reflected its purpose. The name was changed to the Michigan College of Mines in 1897. By 1931 enrollment had reached nearly 600, during the next few years, due to the Great Depression, money was scarce, causing department heads and even the president of the university, William Hotchkiss, to take pay cuts. Dillman was president from 1935 to 1956, during this time, the school underwent many notable changes, including the construction of the Memorial Union Building and purchase of an ice rink and golf course. Around 1948, enrollment passed 2000 students total, in 1956, J. Robert Van Pelt became the new president of the university. He restarted many PhD programs and created a focus on research and this included the schools first analog computation class in 1956–1957. In the final years of his presidency, the changed from a college to a university. The change from the Michigan College of Mining and Technology was necessary for two reasons, according to Van Pelt, First, the college had expanded too greatly and the current name was no longer an accurate title. Also, including mining in the name of the college was misleading, the name Michigan Technological University was chosen in order to retain the nickname Michigan Tech that had already been in use since 1927. Although engineering still accounts for some 59 percent of all enrollment as of fall 2010, along with its new name, the school also gained new constitutional status in 1964
29.
Ignimbrite
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Ignimbrites are made of a very poorly sorted mixture of volcanic ash and pumice lapilli, commonly with scattered lithic fragments. The ash is composed of shards and crystal fragments. Ignimbrites may be loose and unconsolidated, or lithified rock called lapilli-tuff, near the volcanic source, ignimbrites commonly contain thick accumulations of lithic blocks, and distally, many show meter-thick accumulations of rounded cobbles of pumice. Ignimbrites may be white, grey, pink, beige, brown or black depending on their composition, many pale ignimbrites are dacitic or rhyolitic. Darker coloured ignimbrites may be densely welded volcanic glass or, less commonly, there are two main models that have been proposed to explain the deposition of ignimbrites from a pyroclastic density current, the en masse deposition and the progressive aggradation models. The en masse model was proposed by volcanologist Robert Stephen John Sparks in 1976, Sparks attributed the poor sorting in ignimbrites to laminar flows of very high particle concentration. Pyroclastic flows were envisioned as being similar to flows, with a body undergoing laminar flow. The flow would travel as a flow, with an essentially non-deforming mass travelling on a thin shear zone. This would produce a unit with an inversely graded base. There are several problems with the en masse model, since ignimbrite is a deposit, its characteristics cannot completely represent the flow, and the deposit may only record the depositional process. It has been posited that the changes are recording progressive aggradation at the base of the flow from an eruption whose composition changes with time. For this to be so, the base of the flow cannot be turbulent, the instantaneous deposition of an entire body of material is not possible because displacement of the fluid is not possible instantaneously. Any displacement of the fluid would mobilize the upper part of the flow, rheomorphic structures are only observed in high grade ignimbrites. There are two types of flow, post-depositional re-mobilization, and late stage viscous flow. While there is debate in the field of the relative importance of either mechanism. A change from particulate flow to a fluid could cause the rapid en masse cooling in the last few meters. It is also theorized that transformation occurs at a layer at the base of the flow. Another model proposed is that the density current became stationary before the structures form
30.
Pyroclastic flow
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A pyroclastic flow is a fast-moving current of hot gas and volcanic matter, which reaches speeds moving away from a volcano of up to 700 km/h. The gases can reach temperatures of about 1,000 °C, Pyroclastic flows normally touch the ground and hurtle downhill, or spread laterally under gravity. Their speed depends upon the density of the current, the output rate. They are a common and devastating result of explosive eruptions. The word pyroclast is derived from the Greek πῦρ, meaning fire, a name for some pyroclastic flows is nuée ardente, this was first used to describe the disastrous 1902 eruption of Mount Pelée on Martinique. In the dark, these pyroclastic flows glowed red, Pyroclastic flows that contain a much higher proportion of gas to rock are known as fully dilute pyroclastic density currents or pyroclastic surges. The lower density sometimes allows them to flow over higher topographic features or water such as ridges, hills, rivers and seas. They may also contain steam, water and rock at less than 250 °C, cold pyroclastic surges can occur when the eruption is from a vent under a shallow lake or the sea. A pyroclastic flow is a type of gravity current, in literature they are sometimes abbreviated to PDC. There are several mechanisms that can produce a flow, Fountain collapse of an eruption column from a Plinian eruption. In such an eruption, the forcefully ejected from the vent heats the surrounding air. If the erupted jet is unable to heat the air sufficiently, convection currents will not be strong enough to carry the plume upwards and it falls. Fountain collapse of an eruption column associated with a Vulcanian eruption The gas and projectiles create a cloud that is denser than the surrounding air, frothing at the mouth of the vent during degassing of the erupted lava. This can lead to the production of a rock called ignimbrite and this occurred during the eruption of Novarupta in 1912. Gravitational collapse of a dome or spine, with subsequent avalanches. The directional blast when part of a volcano collapses or explodes, as distance from the volcano increases, this rapidly transforms into a gravity-driven current. The volumes range from a few hundred meters to more than a thousand cubic kilometres. The larger ones can travel for hundreds of kilometres, although none on that scale have occurred for several hundred thousand years, most pyroclastic flows are around one to ten cubic kilometres and travel for several kilometres
31.
South Asia
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Topographically, it is dominated by the Indian Plate, which rises above sea level as Nepal and northern parts of India situated south of the Himalayas and the Hindu Kush. South Asia is bounded on the south by the Indian Ocean and on land by West Asia, Central Asia, East Asia, the current territories of Afghanistan, Bangladesh, Bhutan, Maldives, Nepal, India, Pakistan, and Sri Lanka form the countries of South Asia. The South Asian Association for Regional Cooperation is an economic cooperation organisation in the region which was established in 1985, South Asia covers about 5.1 million km², which is 11. 51% of the Asian continent or 3. 4% of the worlds land surface area. The population of South Asia is about 1.749 billion or about one fourth of the worlds population, overall, it accounts for about 39. 49% of Asias population and is home to a vast array of peoples. The area of South Asia and its extent is not clear cut as systemic. Aside from the region of South Asia, formerly part of the British Empire, there is a high degree of variation as to which other countries are included in South Asia. Modern definitions of South Asia are consistent in including Afghanistan, India, Pakistan, Bangladesh, Sri Lanka, Nepal, Bhutan, Myanmar is included by some scholars in South Asia, but in Southeast Asia by others. Some do not include Afghanistan, others question whether Afghanistan should be considered a part of South Asia or the Middle East, the mountain countries of Nepal and Bhutan, and the island countries of Sri Lanka and Maldives are generally included as well. Myanmar is often added, and by various deviating definitions based on often substantially different reasons, the British Indian Ocean Territory, the common concept of South Asia is largely inherited from the administrative boundaries of the British Raj, with several exceptions. The Aden Colony, British Somaliland and Singapore, though administered at various times under the Raj, have not been proposed as any part of South Asia. Additionally Burma was administered as part of the Raj until 1937, the 562 princely states that were protected by but not directly ruled by the Raj became administrative parts of South Asia upon joining Union of India or Dominion of Pakistan. China and Myanmar have also applied for the status of members of SAARC. This bloc of countries include two independent countries that were not part of the British Raj – Nepal, and Bhutan, Afghanistan was a British protectorate from 1878 until 1919, after the Afghans lost to the British in the Second Anglo-Afghan war. The United Nations Statistics Divisions scheme of sub-regions include all eight members of the SAARC as part of Southern Asia, population Information Network includes Afghanistan, Bangladesh, Burma, India, Nepal, Pakistan and Sri Lanka as part of South Asia. Maldives, in view of its characteristics, was admitted as a member Pacific POPIN subregional network only in principle, the Hirschman–Herfindahl index of the United Nations Economic and Social Commission for Asia and the Pacific for the region includes only the original seven signatories of SAARC. The British Indian Ocean Territory is connected to the region by a publication of Janes for security considerations, the inclusion of Myanmar in South Asia is without consensus, with many considering it a part of southeast Asia and others including it within South Asia. Afghanistan was of importance to the British colonial empire, especially after the Second Anglo-Afghan War over 1878–1880, Afghanistan remained a British protectorate until 1919, when a treaty with Vladimir Lenin included the granting of independence to Afghanistan. Following Indias partition, Afghanistan has generally included in South Asia
32.
Malaysia
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Malaysia is a federal constitutional monarchy located in Southeast Asia. Peninsular Malaysia shares a land and maritime border with Thailand and maritime borders with Singapore, Vietnam, East Malaysia shares land and maritime borders with Brunei and Indonesia and a maritime border with the Philippines and Vietnam. The capital city is Kuala Lumpur, while Putrajaya is the seat of the federal government, with a population of over 30 million, Malaysia is the 44th most populous country. The southernmost point of continental Eurasia, Tanjung Piai, is in Malaysia, located in the tropics, Malaysia is one of 17 megadiverse countries on earth, with large numbers of endemic species. Malaysia has its origins in the Malay kingdoms present in the area which, from the 18th century, the first British territories were known as the Straits Settlements, whose establishment was followed by the Malay kingdoms becoming British protectorates. The territories on Peninsular Malaysia were first unified as the Malayan Union in 1946, Malaya was restructured as the Federation of Malaya in 1948, and achieved independence on 31 August 1957. Malaya united with North Borneo, Sarawak, and Singapore on 16 September 1963 to become Malaysia, less than two years later in 1965, Singapore was expelled from the federation. The country is multi-ethnic and multi-cultural, which plays a role in politics. About half the population is ethnically Malay, with minorities of Malaysian Chinese, Malaysian Indians. The constitution declares Islam the state religion while allowing freedom of religion for non-Muslims, the government system is closely modelled on the Westminster parliamentary system and the legal system is based on common law. The head of state is the king, known as the Yang di-Pertuan Agong and he is an elected monarch chosen from the hereditary rulers of the nine Malay states every five years. The head of government is the prime minister, since its independence, Malaysia has had one of the best economic records in Asia, with its GDP growing at an average of 6. 5% per annum for almost 50 years. The economy has traditionally been fuelled by its resources, but is expanding in the sectors of science, tourism, commerce. Today, Malaysia has a newly industrialised market economy, ranked third largest in Southeast Asia, the name Malaysia is a combination of the word Malay and the Latin-Greek suffix -sia/-σία. The word melayu in Malay may derive from the Tamil words malai and ur meaning mountain and city, land, malayadvipa was the word used by ancient Indian traders when referring to the Malay Peninsula. Whether or not it originated from these roots, the word melayu or mlayu may have used in early Malay/Javanese to mean to steadily accelerate or run. This term was applied to describe the current of the river Melayu in Sumatra. The name was adopted by the Melayu Kingdom that existed in the seventh century on Sumatra
33.
Tonne
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The SI symbol for the tonne is t, adopted at the same time as the unit itself in 1879. Its use is also official, for the metric ton, within the United States, having been adopted by the US National Institute of Standards and it is a symbol, not an abbreviation, and should not be followed by a period. Informal and non-approved symbols or abbreviations include T, mT, MT, in French and all English-speaking countries that are predominantly metric, tonne is the correct spelling. Before metrication in the UK the unit used for most purposes was the Imperial ton of 2,240 pounds avoirdupois, equivalent to 1,016 kg, differing by just 1. 6% from the tonne. Ton and tonne are both derived from a Germanic word in use in the North Sea area since the Middle Ages to designate a large cask. A full tun, standing about a high, could easily weigh a tonne. An English tun of wine weighs roughly a tonne,954 kg if full of water, in the United States, the unit was originally referred to using the French words millier or tonneau, but these terms are now obsolete. The Imperial and US customary units comparable to the tonne are both spelled ton in English, though they differ in mass, one tonne is equivalent to, Metric/SI,1 megagram. Equal to 1000000 grams or 1000 kilograms, megagram, Mg, is the official SI unit. Mg is distinct from mg, milligram, pounds, Exactly 1000/0. 453 592 37 lb, or approximately 2204.622622 lb. US/Short tons, Exactly 1/0. 907 184 74 short tons, or approximately 1.102311311 ST. One short ton is exactly 0.90718474 t, imperial/Long tons, Exactly 1/1. 016 046 9088 long tons, or approximately 0.9842065276 LT. One long ton is exactly 1.0160469088 t, for multiples of the tonne, it is more usual to speak of thousands or millions of tonnes. Kilotonne, megatonne, and gigatonne are more used for the energy of nuclear explosions and other events. When used in context, there is little need to distinguish between metric and other tons, and the unit is spelt either as ton or tonne with the relevant prefix attached. *The equivalent units columns use the short scale large-number naming system used in most English-language countries. †Values in the equivalent short and long tons columns are rounded to five significant figures, ǂThough non-standard, the symbol kt is also sometimes used for knot, a unit of speed for sea-going vessels, and should not be confused with kilotonne. A metric ton unit can mean 10 kilograms within metal trading and it traditionally referred to a metric ton of ore containing 1% of metal. In the case of uranium, the acronym MTU is sometimes considered to be metric ton of uranium, in the petroleum industry the tonne of oil equivalent is a unit of energy, the amount of energy released by burning one tonne of crude oil, approximately 42 GJ
34.
Sulfurous acid
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Sulfurous acid is the chemical compound with the formula H2SO3. There is no evidence that sulfurous acid exists in solution, the conjugate bases of this elusive acid are, however, common anions, bisulfite and sulfite. Sulfurous acid is a species in the formation of acid rain from sulfur dioxide. Raman spectra of solutions of sulfur dioxide in water show only signals due to the SO2 molecule, the intensities of the signals are consistent with the following equilibrium, SO2 + H2O ⇌ HSO−3 + H+ Ka =1. 54×10−2, pKa =1.81. In cooling down a clathrate SO2 ·5.75 H2O will crystallise which decomposes again at 7 °C, thus sulfurous acid H2SO3 cannot be isolated. Aqueous solutions of sulfur dioxide, which sometimes are referred to as acid, are used as reducing agents and as disinfectants. They are oxidised to sulfuric acid or sulfate by accepting another oxygen atom and they are also mild bleaches, and are used for materials which may be damaged by chlorine-containing bleaches. Bisulfite Carbonic acid Pulp Sulfite paper pulp process Sulfite Sulfuric acid
35.
Landsat program
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The Landsat program is the longest-running enterprise for acquisition of satellite imagery of Earth. On July 23,1972 the Earth Resources Technology Satellite was launched and this was eventually renamed to Landsat. The most recent, Landsat 8, was launched on February 11,2013, the instruments on the Landsat satellites have acquired millions of images. Landsat 7 data has eight spectral bands with spatial resolutions ranging from 15 to 60 meters, Landsat images are usually divided into scenes for easy downloading. Each Landsat scene is about 115 miles long and 115 miles wide, Hughes Santa Barbara Research Center initiated, designed, and fabricated the first three Multispectral Scanners in 1969, the same year man landed on the moon. The first prototype MSS was completed nine months, in the fall of 1970. It was tested by scanning Half Dome at Yosemite National Park, the program was initially called the Earth Resources Technology Satellites Program, which was used from 1966 to 1975. In 1975, the name was changed to Landsat and this occurred in 1985 when the Earth Observation Satellite Company, a partnership of Hughes Aircraft and RCA, was selected by NOAA to operate the Landsat system with a ten-year contract. EOSAT operated Landsat 4 and Landsat 5, had rights to market Landsat data. In 1989, this transition had not been completed when NOAAs funding for the Landsat program was due to run out. The head of the newly formed National Space Council, Vice President Dan Quayle, noted the situation and arranged emergency funding that allowed the program to continue with the data archives intact. Again in 1990 and 1991, Congress provided only half of the funding to NOAA. In 1992, various efforts were made to procure funding for follow on Landsats and continued operations, Landsat 6 was finally launched on October 5,1993, but was lost in a launch failure. Processing of Landsat 4 and 5 data was resumed by EOSAT in 1994, NASA finally launched Landsat 7 on April 15,1999. Timeline Landsat missions 1 through 5 carried the Landsat Multispectral Scanner and this construct ensured the secondary mirror would simply oscillate about the primary optic axis to maintain focus despite vibration inherent from the 360 mm beryllium scan mirror. This engineering solution allowed the United States to develop LANDSAT at least five years ahead of the French SPOT and this was a direct result of the commercialization efforts begun under the Carter administration, though finally completed under the Reagan administration. This main plate was assembled on a frame, then attached to the magnesium housing with helicoil fasteners. Key to the success of the multi spectral scanner was the scan monitor mounted on the underbelly of the magnesium housing, the beam struck the beryllium scan mirror seven times as it reflected seven times off the flat mirrors
36.
Monsoon
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Usually, the term monsoon is used to refer to the rainy phase of a seasonally changing pattern, although technically there is also a dry phase. The term is sometimes used for locally heavy but short-term rains. The major monsoon systems of the world consist of the West African and Asia-Australian monsoons, the inclusion of the North and South American monsoons with incomplete wind reversal has been debated. The south-west monsoon winds are called Nairutya Maarut in India, the English monsoon came from Portuguese monção, ultimately from Arabic mawsim and/or Hindi mausam, perhaps partly via early modern Dutch monsun. Strengthening of the Asian monsoon has been linked to the uplift of the Tibetan Plateau after the collision of the Indian sub-continent and Asia around 50 million years ago. Because of studies of records from the Arabian Sea and that of the wind-blown dust in the Loess Plateau of China, testing of this hypothesis awaits deep ocean sampling by the Integrated Ocean Drilling Program. The monsoon has varied significantly in strength since this time, largely linked to climate change. A study of marine plankton suggested that the Indian Monsoon strengthened around 5 million years ago, then, during ice periods, the sea level fell and the Indonesian Seaway closed. When this happened, cold waters in the Pacific were impeded from flowing into the Indian Ocean and it is believed that the resulting increase in sea surface temperatures in the Indian Ocean increased the intensity of monsoons. Five episodes during the Quaternary at 2.22 Ma,1.83 Ma,0.68 Ma,0.45 Ma and 0.04 Ma were identified which showed a weakening of Leeuwin Current. The weakening of the LC would have an effect on the sea surface temperature field in the Indian Ocean, thus these five intervals could probably be those of considerable lowering of SST in the Indian Ocean and would have influenced Indian monsoon intensity. The impact of monsoon on the weather is different from place to place. In some places there is just a likelihood of having a more or less rain. In other places, quasi semi-deserts are turned into green grasslands where all sorts of plants. The Indian Monsoon turns large parts of India from a kind of semi-desert into green lands, see photos only taken 3 months apart in the Western Ghats. In places like this it is crucial for farmers to have the right timing for putting the seeds on the fields, Monsoons are large-scale sea breezes which occur when the temperature on land is significantly warmer or cooler than the temperature of the ocean. These temperature imbalances happen because oceans and land absorb heat in different ways, in contrast, dirt, sand, and rocks have lower heat capacities, and they can only transmit heat into the earth by conduction and not by convection. Therefore, bodies of water stay at an even temperature
37.
Ice core
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An ice core is a core sample that is typically removed from an ice sheet, most commonly from the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere. As the ice forms from the buildup of annual layers of snow, lower layers are older than upper. The properties of the ice and the recrystallized inclusions within the ice can then be used to reconstruct a record over the age range of the core. This enables the reconstruction of local records and the history of atmospheric composition. Ice cores contain an abundance of information about climate, inclusions in the snow of each year remain in the ice, such as wind-blown dust, ash, pollen, bubbles of atmospheric gas and radioactive substances. The variety of climatic proxies is greater than in any other natural recorder of climate, the length of the record depends on the depth of the ice core and varies from a few years up to 800 kyr for the EPICA core. The time resolution depends on the amount of snowfall. Upper layers of ice in a core correspond to a year or sometimes a single season. Deeper into the ice the layers thin and annual layers become indistinguishable and it is the simultaneity of these properties recorded in the ice that makes ice cores such a powerful tool in paleoclimate research. Ice sheets are formed from snow, because an ice sheet survives summer, the temperature in that location usually does not warm much above freezing. In many locations in Antarctica the air temperature is well below the freezing point of water. If the summer temperatures do get above freezing, any ice core record will be degraded or completely useless. The surface layer is snow in various forms, with air gaps between snowflakes, as snow continues to accumulate, the buried snow is compressed and forms firn, a grainy material with a texture similar to granulated sugar. Air gaps remain, and some circulation of air continues, as snow accumulates above, the firn continues to densify, and at some point the pores close off and the air is trapped. Because the air continues to circulate until then, the ice age and the age of the gas enclosed are not the same, the gas age–ice age difference is as great as 7 kyr in glacial ice from Vostok. Under increasing pressure, at depth the firn is compressed into ice. This depth may range between a few to tens of meters to typically 100 m for Antarctic cores. Below this level material is frozen in the ice, Ice may appear clear or blue
38.
Greenland
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Greenland is an autonomous constituent country within the Danish Realm between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for more than a millennium. The majority of its residents are Inuit, whose ancestors began migrating from the Canadian mainland in the 13th century, Greenland is the worlds largest island. Three-quarters of Greenland is covered by the permanent ice sheet outside Antarctica. With a population of about 56,480, it is the least densely populated country in the world, the Arctic Umiaq Line ferry acts as a lifeline for western Greenland, connecting the various cities and settlements. Greenland has been inhabited off and on for at least the last 4,500 years by Arctic peoples whose forebears migrated there from what is now Canada, Norsemen settled the uninhabited southern part of Greenland beginning in the 10th century, and Inuit peoples arrived in the 13th century. The Norse colonies disappeared in the late 15th century, soon after their demise, beginning in 1499, the Portuguese briefly explored and claimed the island, naming it Terra do Lavrador. In the early 18th century, Scandinavian explorers reached Greenland again, to strengthen trading and power, Denmark-Norway affirmed sovereignty over the island. Greenland was settled by Vikings more than a thousand years ago, Vikings set sail from Greenland and Iceland, discovering North America nearly 500 years before Columbus reached Caribbean islands. Though under continuous influence of Norway and Norwegians, Greenland was not formally under the Norwegian crown until 1262, the Kingdom of Norway was extensive and a military power until the mid-14th century. Thus, the two kingdoms resources were directed at creating Copenhagen, Norway became the weaker part and lost sovereignty over Greenland in 1814 when the union was dissolved. Greenland became a Danish colony in 1814, and was made a part of the Danish Realm in 1953 under the Constitution of Denmark, in 1973, Greenland joined the European Economic Community with Denmark. However, in a referendum in 1982, a majority of the population voted for Greenland to withdraw from the EEC which was effected in 1985, Greenland contains the worlds largest and most northernly national park, Northeast Greenland National Park. Greenland is divided into four municipalities - Sermersooq, Kujalleq, Qaasuitsup and it also retains control of monetary policy, providing an initial annual subsidy of DKK3.4 billion, which is planned to diminish gradually over time. Greenland expects to grow its economy based on increased income from the extraction of natural resources, the capital, Nuuk, held the 2016 Arctic Winter Games. At 70%, Greenland has one of the highest shares of renewable energy in the world, the early Viking settlers named the island as Greenland. In the Icelandic sagas, the Norwegian-born Icelander Erik the Red was said to be exiled from Iceland for manslaughter, along with his extended family and his thralls, he set out in ships to explore an icy land known to lie to the northwest. After finding an area and settling there, he named it Grœnland
39.
Greenland Ice Sheet Project
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The Greenland Ice Sheet Project was a decade-long project to drill ice cores in Greenland that involved scientists and funding agencies from Denmark, Switzerland and the United States. Besides the U. S. National Science Foundation, funding was provided by the Swiss National Science Foundation, the ice cores provide a proxy archive of temperature and atmospheric constituents that help to understand past climate variations. The preliminary GISP field work started in 1971 at Dye 3, after this, annual field expeditions were carried out to drill intermediate depth cores at various locations on the ice sheet. The first was a 398 m core at Milcent and another was a 405 m core at the Crete station in 1974, in the first year, an 18 cm diameter hole was drilled and cased to a depth of 80 m. Coring continued for two seasons, and on August 10,1981, bedrock was reached at a depth of 2037 m. The Dye 3 site was a compromise, glaciologically, a site on the ice divide with smooth bedrock would have been better, logistically. There was a follow-up U. S. GISP2 project, which drilled at a better location on the summit of the ice sheet. This hit bedrock on July 1,1993 after five years of drilling, GISP2 produced an ice core 3053.44 meters in depth, the deepest ice core recovered in the world at the time. The location of the GISP2 drilling was revisited annually during summer campaigns to investigate the properties of gasses. Eventually, GISP2 and Summit Camp became the site of a year round NSF / NOAA climate observatory, the bulk of the GISP2 ice core is archived at the National Ice Core Laboratory in Lakewood, Colorado, United States. Clair Patterson Dye 3 EPICA North Greenland Ice Core Project GISP from the NOAA World Data Center for paleoclimatology GISP2
40.
Sulfuric acid
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Sulfuric acid is a highly corrosive strong mineral acid with the molecular formula H2SO4 and molecular weight 98.079 g/mol. It is a pungent-ethereal, colorless to slightly yellow liquid that is soluble in water at all concentrations. Sometimes, it is dyed dark brown during production to alert people to its hazards, the historical name of this acid is oil of vitriol. Sulfuric acid is an acid and shows different properties depending upon its concentration. Its corrosiveness on other materials, like metals, living tissues or even stones, can be ascribed to its strong acidic nature and, if concentrated. It is also hygroscopic, readily absorbing water vapour from the air, Sulfuric acid at a high concentration can cause very serious damage upon contact, since not only does it cause chemical burns via hydrolysis, but also secondary thermal burns through dehydration. It can lead to permanent blindness if splashed onto eyes and irreversible damage if swallowed, Sulfuric acid has a wide range of applications including in domestic acidic drain cleaners, as an electrolyte in lead-acid batteries and in various cleaning agents. It is also a central substance in the chemical industry, principal uses include mineral processing, fertilizer manufacturing, oil refining, wastewater processing, and chemical synthesis. It is widely produced with different methods, such as process, wet sulfuric acid process, lead chamber process. The study of vitriol, a category of glassy minerals from which the acid can be derived, sumerians had a list of types of vitriol that they classified according to the substances color. Some of the earliest discussions on the origin and properties of vitriol is in the works of the Greek physician Dioscorides, galen also discussed its medical use. Ibn Sina focused on its uses and different varieties of vitriol. Sulfuric acid was called oil of vitriol by medieval European alchemists because it was prepared by roasting green vitriol in an iron retort, there are references to it in the works of Vincent of Beauvais and in the Compositum de Compositis ascribed to Saint Albertus Magnus. A passage from Pseudo-Geber´s Summa Perfectionis was long considered to be the first recipe for sulfuric acid, in the seventeenth century, the German-Dutch chemist Johann Glauber prepared sulfuric acid by burning sulfur together with saltpeter, in the presence of steam. As saltpeter decomposes, it oxidizes the sulfur to SO3, in 1736, Joshua Ward, a London pharmacist, used this method to begin the first large-scale production of sulfuric acid. This process allowed the effective industrialization of sulfuric acid production, after several refinements, this method, called the lead chamber process or chamber process, remained the standard for sulfuric acid production for almost two centuries. Sulfuric acid created by John Roebucks process approached a 65% concentration, later refinements to the lead chamber process by French chemist Joseph Louis Gay-Lussac and British chemist John Glover improved concentration to 78%. However, the manufacture of dyes and other chemical processes require a more concentrated product
41.
Mitochondrial DNA
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Mitochondrial DNA is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, adenosine triphosphate. Mitochondrial DNA is only a portion of the DNA in a eukaryotic cell, most of the DNA can be found in the cell nucleus and, in plants and algae. In humans, the 16,569 base pairs of mitochondrial DNA encode for only 37 genes, human mitochondrial DNA was the first significant part of the human genome to be sequenced. In most species, including humans, mtDNA is inherited solely from the mother, since animal mtDNA evolves faster than nuclear genetic markers, it represents a mainstay of phylogenetics and evolutionary biology. It also permits an examination of the relatedness of populations, and so has become important in anthropology and this theory is called the endosymbiotic theory. Each mitochondrion is estimated to contain 2–10 mtDNA copies, the reasons why mitochondria have retained some genes are debated. Recent analysis of a range of mtDNA genomes suggests that both these features may dictate mitochondrial gene retention. In most multicellular organisms, mtDNA is inherited from the mother, mechanisms for this include simple dilution, degradation of sperm mtDNA in the male genital tract, in the fertilized egg, and, at least in a few organisms, failure of sperm mtDNA to enter the egg. Whatever the mechanism, this single parent pattern of inheritance is found in most animals, most plants. In sexual reproduction, mitochondria are inherited exclusively from the mother. Also, most mitochondria are present at the base of the sperms tail, in 1999 it was reported that paternal sperm mitochondria are marked with ubiquitin to select them for later destruction inside the embryo. Some in vitro techniques, particularly injecting a sperm into an oocyte. The fact that mitochondrial DNA is maternally inherited enables researchers to trace maternal lineage far back in time. This is usually accomplished on human mitochondrial DNA by sequencing the hypervariable control regions, hVR1, for example, consists of about 440 base pairs. These 440 base pairs are then compared to the regions of other individuals to determine maternal lineage. Most often, the comparison is made to the revised Cambridge Reference Sequence, vilà et al. have published studies tracing the matrilineal descent of domestic dogs to wolves. The concept of the Mitochondrial Eve is based on the type of analysis. MtDNA is highly conserved, and its relatively slow mutation rates make it useful for studying the evolutionary relationships—phylogeny—of organisms, biologists can determine and then compare mtDNA sequences among different species and use the comparisons to build an evolutionary tree for the species examined
42.
Genetic bottleneck
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A population bottleneck is a sharp reduction in the size of a population due to environmental events or human activities. Genetic diversity remains lower, only slowly increasing with time as random mutations occur and this genetic drift can change the proportional distribution of an allele by chance and even lead to fixation or loss of alleles. Due to the population size after a bottleneck event, the chance of inbreeding and genetic homogeneity increases. Population bottlenecks play an important role in biology and in the context of agriculture. That said, the possibility of a severe recent species-wide bottleneck can be ruled out, parallel bottlenecks were proposed to exist among chimpanzees, gorillas, rhesus macaques, orangutans and tigers. The hypothesis was based on evidence of sudden climate change and on coalescence evidence of some genes. However, subsequent research, especially in the 2010s, appeared to both the climate argument and the genetic argument. Recent research shows the extent of change was much smaller than believed by proponents of the theory. In addition, coalescence times for Y-chromosomal and mitochondrial DNA have been revised to well above 100,000 years since 2011, genetic material inherited exclusively from either father or mother can be traced back in time via either matrilineal or patrilineal ancestry. In 2000, a Molecular Biology and Evolution paper suggested a model or a long bottleneck to account for the limited genetic variation. European bison, also called wisent, faced extinction in the early 20th century, the animals living today are all descended from 12 individuals and they have extremely low genetic variation, which may be beginning to affect the reproductive ability of bulls. The population of American bison fell due to overhunting, nearly leading to extinction around the year 1890, a classic example of a population bottleneck is that of the northern elephant seal, whose population fell to about 30 in the 1890s. Although it now numbers in the hundreds of thousands, the potential for bottlenecks within colonies remains, dominant bulls are able to mate with the largest number of females — sometimes as many as 100. With so much of a colonys offspring descended from just one dominant male, genetic diversity is limited, making the more vulnerable to diseases. The genome of the giant panda shows evidence of a bottleneck that took place about 43,000 years ago. There is also evidence of at least one species, the golden snub-nosed monkey. Further deductions can sometimes be inferred from a population bottleneck. DNA analyses date the bottleneck to around 88,000 years before present, about 100,000 YBP the volcano erupted violently, burying much of the tortoise habitat deep in pumice and ash
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Lake Toba travel guide from Wikivoyage