1.
Mount Mazama
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Mount Mazama is a stratovolcano in the Oregon segment of the Cascade Volcanic Arc and the Cascade Range located in the United States. The volcanos collapsed caldera holds Crater Lake, and the mountain is located within Crater Lake National Park. Its caldera was created by an eruption 42 times greater than the one of Mount St. Helens in 1980, Mazamas summit was destroyed by a volcanic eruption that occurred around 5677 BC, ±150 years. The eruption reduced Mazamas approximate 12, 000-foot height by about 1 mile, much of the volcano fell into the volcanos partially emptied neck and magma chamber. At 8,159 feet, Hillman Peak is now the highest point on the rim, the Klamath Native Americans of the area believed that the mountain was inhabited by Llao, their god of the underworld. After the mountain destroyed itself the Klamaths recounted the events as a battle between Llao and his rival Skell, their sky god. Mazama started to grow around 400,000 years ago in the Pleistocene and these early flows averaged 20 to 30 feet thick and appear to have been emplaced over a few years to a few centuries. Several shield volcanoes were created by these flows and numerous cinder cones grew in the immediate area, more explosive eruptions started around 75,000 years ago and built a westward-trending line of composite cones. Cone building eruptions lasted until around 50,000 years ago when lava flowed down Mazamas north. Relatively few of the cone building eruptions issued from the vent, resulting in a highly complex, approximately 11, 000-foot structure made of overlapping composite cones. Consequently, Mazamas base was broader and its sides not as steep as todays Mount Shasta, after its cone building phase, Mazama lavas became increasingly silica-rich and viscous - two conditions that tend to trap explosive gases. The first major eruption in this new cycle of Mazamas life occurred about 10,000 years later and these structures were subsequently destroyed by either collapse or steam explosions. Either way, their destruction created large landslides that left deposits at the head of Munson Valley, Mazamas next major eruptive period occurred between 25,000 and 30,000 years ago and extruded rhyodacite lava. These thick, slow moving, pasty flows erupted from a vent on Mazamas northeast flank and solidified to form 600-foot high Redcloud Cliff, the volcano then went dormant for roughly the next 20,000 years, while successive ice age glaciers cut large valleys into the mountains sides. One of the largest glaciers flowed down Munson Valley near the present location of headquarters, down Annie Creek Valley. When the last ice age ended 12,000 years ago, while Mazama slept, its magma chamber was going through some differentiation, with lighter, more gas- and silica-rich rocks collecting closer to the surface. Around 5677 BC Mazama awoke from its slumber with explosive eruptions on the northern part of the main summit where Llao Rock now resides. Great quantities of pumice and ash were ejected as a crater was excavated by the explosions
2.
Cauldron
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A cauldron is a large metal pot for cooking and/or boiling over an open fire, with a large mouth and frequently with an arc-shaped hanger. The word cauldron is first recorded in Middle English as caudroun and it was borrowed from Norman caudron. It represents the evolution of Vulgar Latin *caldario for Classical Latin caldārium hot bath. The Norman-French word replaces probably the not initial new English sentence ċetel, the word kettle is a borrowing of the Old Norse variant ketill cauldron. Cauldrons have largely fallen out of use in the world as cooking vessels. In fiction, witches often prepare their potions in a cauldron, also, in Irish folklore, a cauldron is purported to be where leprechauns keep their gold and treasure. In some forms of Wicca, incorporating aspects of Celtic mythology, welsh legend also tells of cauldrons that were useful to warring armies. It was suspected that they lacked souls and these warriors could go back into battle until they were killed again. In Wicca and some forms of neopagan or pagan belief systems the cauldron is still used in magical practices. Most often a cauldron is made of cast iron and is used to burn incense on a charcoal disc, to make black salt, for mixing herbs. Cauldrons symbolize not only the Goddess but also represent the womb, cauldrons are often sold in New Age or metaphysical stores and may have various symbols of power inscribed on them. This may have resulted from the combination of the legend with earlier Celtic myths of magical cauldrons. The common translation for ding is often referred to as a cauldron, in Chinese history and culture, possession of one or more ancient dings is often associated with power and dominion over the land. Therefore, the ding is often used as a symbolism for power. The term inquiring of the ding is often used interchangeably with the quest for power
3.
Magma chamber
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A magma chamber is a large underground pool of liquid rock found beneath the surface of the Earth. The molten rock in such a chamber is under pressure, and given enough time. If it finds a way to the surface, then the result will be a volcanic eruption, magma chambers are hard to detect, and most of the known ones are therefore close to the surface of the Earth, commonly between 1 km and 10 km under the surface. In geological terms, this is close to the surface, although in human terms. Magma rises through cracks from beneath and across the crust because it is less dense than the surrounding rock, when the magma cannot find a path upwards it pools into a magma chamber. Magma chambers are built up incrementally, by successive horizontal or vertical magma injections. Influx of new magma causes reaction of pre-existing crystals and the pressure in the chamber to increase, upon cooling, new mineral phases saturate and the rock type changes, typically forming gabbro, diorite, tonalite and granite or gabbro, diorite, syenite and granite. If magma resides in a chamber for a period, then it can become stratified with lower density components rising to the top. Rocks accumulate in layers, forming a layered intrusion, additionally, the removal of the lower melting point components will tend to make the magma more viscous. If the magma is not vented to the surface in an eruption, it will slowly cool. Often, a volcano may have a deep magma chamber many kilometers down, as a volcano erupts, emptying the magma chamber, the surrounding rock will collapse into it. If a large amount of magma is erupted, causing the chamber to reduce considerably in volume, then this can result in a depression at the surface called a caldera
4.
Volcanic crater
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A volcanic crater is a roughly circular depression in the ground caused by volcanic activity. It is typically a bowl-shaped feature within which occurs a vent or vents, a volcanic crater can be of large dimensions, and sometimes of great depth. During certain types of eruptions, a volcanos magma chamber may empty enough for an area above it to subside. In most volcanoes, the crater is situated at the top of a formed from the erupted volcanic deposits such as lava flows. Volcanoes that terminate in such a summit crater are usually of a conical form, other volcanic craters may be found on the flanks of volcanoes, and these are commonly referred to as flank craters. Some volcanic craters may fill either fully or partially with rain and/or melted snow, a crater may be breached during an eruption, either by explosions or by lava, or through later erosion. Breached craters have a lower rim on one side. Some volcanoes, such as maars, consist of a crater alone and these volcanic explosion craters are formed when magma rises through water-saturated rocks and causes a phreatic eruption. Volcanic craters from phreatic eruptions often occur on plains away from other obvious volcanoes
5.
Sinkhole
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A sinkhole, also known as a cenote, sink, sink-hole, shakehole, swallet, swallow hole, or doline, is a depression or hole in the ground caused by some form of collapse of the surface layer. Most are caused by karst processes—for example, the dissolution of carbonate rocks or suffosion processes. Sinkholes vary in size from 1 to 600 m both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms, sinkholes may form gradually or suddenly, and are found worldwide. Sinkholes may capture surface drainage from running or standing water, but may form in high. Sinkholes that capture drainage can hold it in limestone caves. These caves may drain into tributaries of larger rivers, the formation of sinkholes involves natural processes of erosion or gradual removal of slightly soluble bedrock by percolating water, the collapse of a cave roof, or a lowering of the water table. Sinkholes often form through the process of suffosion, for example, groundwater may dissolve the carbonate cement holding the sandstone particles together and then carry away the lax particles, gradually forming a void. Occasionally a sinkhole may exhibit a visible opening into a cave below, sinkholes also occur in sandstone and quartzite terrains. As the rock dissolves, spaces and caverns develop underground and these sinkholes can be dramatic, because the surface land usually stays intact until there is not enough support. Then, a collapse of the land surface can occur. Sinkholes also form from human activity, such as the collapse of abandoned mines and salt cavern storage in salt domes in places like Louisiana, Mississippi, more commonly, sinkholes occur in urban areas due to water main breaks or sewer collapses when old pipes give way. They can also occur from the overpumping and extraction of groundwater, sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Sinkholes tend to occur in karst landscapes, karst landscapes can have up to thousands of sinkholes within a small area, giving the landscape a pock-marked appearance. These sinkholes drain all the water, so there are only subterranean rivers in these areas, examples of karst landscapes with a plethora of massive sinkholes include Khammouan Mountains and Mamo Plateau. The largest known sinkholes formed in sandstone are Sima Humboldt and Sima Martel in Venezuela, some sinkholes form in thick layers of homogenous limestone. On the contact of limestone and insoluble rock below it, powerful underground rivers may form, in such conditions, the largest known sinkholes of the world have formed, like the 662-metre deep Xiaozhai Tiankeng, giant sótanos in Querétaro and San Luis Potosí states in Mexico and others. The state of Florida in the United States is known for having frequent sinkhole collapses, the Murge area in southern Italy also has numerous sinkholes. Sinkholes can be formed in retention ponds from large amounts of rain, an analysis of a case of sinkhole formation under a retention pond due to a large amount of rain can be seen in a sinkhole collapse study
6.
Spanish language
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Spanish —also called Castilian —is a Romance language that originated in the Castile region of Spain, with hundreds of millions of native speakers around the world. It is usually considered the worlds second-most spoken native language after Mandarin Chinese and it is one of the few languages to use inverted question and exclamation marks. Spanish is a part of the Ibero-Romance group of languages, which evolved from several dialects of Vulgar Latin in Iberia after the collapse of the Western Roman Empire in the 5th century. Beginning in the early 16th century, Spanish was taken to the colonies of the Spanish Empire, most notably to the Americas, as well as territories in Africa, Oceania, around 75% of modern Spanish is derived from Latin. Greek has also contributed substantially to Spanish vocabulary, especially through Latin, Spanish vocabulary has been in contact from an early date with Arabic, having developed during the Al-Andalus era in the Iberian Peninsula. With around 8% of its vocabulary being Arabic in origin, this language is the second most important influence after Latin and it has also been influenced by Basque as well as by neighboring Ibero-Romance languages. It also adopted words from languages such as Gothic language from the Visigoths in which many Spanish names and surnames have a Visigothic origin. Spanish is one of the six languages of the United Nations. It is the language in the world by the number of people who speak it as a mother tongue, after Mandarin Chinese. It is estimated more than 437 million people speak Spanish as a native language. Spanish is the official or national language in Spain, Equatorial Guinea, speakers in the Americas total some 418 million. In the European Union, Spanish is the tongue of 8% of the population. Spanish is the most popular second language learned in the United States, in 2011 it was estimated by the American Community Survey that of the 55 million Hispanic United States residents who are five years of age and over,38 million speak Spanish at home. The Spanish Constitution of 1978 uses the term castellano to define the language of the whole Spanish State in contrast to las demás lenguas españolas. Article III reads as follows, El castellano es la lengua española oficial del Estado, las demás lenguas españolas serán también oficiales en las respectivas Comunidades Autónomas. Castilian is the official Spanish language of the State, the other Spanish languages as well shall be official in their respective Autonomous Communities. The Spanish Royal Academy, on the hand, currently uses the term español in its publications. Two etymologies for español have been suggested, the Spanish Royal Academy Dictionary derives the term from the Provençal word espaignol, and that in turn from the Medieval Latin word Hispaniolus, from—or pertaining to—Hispania
7.
Latin
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Latin is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets, Latin was originally spoken in Latium, in the Italian Peninsula. Through the power of the Roman Republic, it became the dominant language, Vulgar Latin developed into the Romance languages, such as Italian, Portuguese, Spanish, French, and Romanian. Latin, Italian and French have contributed many words to the English language, Latin and Ancient Greek roots are used in theology, biology, and medicine. By the late Roman Republic, Old Latin had been standardised into Classical Latin, Vulgar Latin was the colloquial form spoken during the same time and attested in inscriptions and the works of comic playwrights like Plautus and Terence. Late Latin is the language from the 3rd century. Later, Early Modern Latin and Modern Latin evolved, Latin was used as the language of international communication, scholarship, and science until well into the 18th century, when it began to be supplanted by vernaculars. Ecclesiastical Latin remains the language of the Holy See and the Roman Rite of the Catholic Church. Today, many students, scholars and members of the Catholic clergy speak Latin fluently and it is taught in primary, secondary and postsecondary educational institutions around the world. The language has been passed down through various forms, some inscriptions have been published in an internationally agreed, monumental, multivolume series, the Corpus Inscriptionum Latinarum. Authors and publishers vary, but the format is about the same, volumes detailing inscriptions with a critical apparatus stating the provenance, the reading and interpretation of these inscriptions is the subject matter of the field of epigraphy. The works of several hundred ancient authors who wrote in Latin have survived in whole or in part and they are in part the subject matter of the field of classics. The Cat in the Hat, and a book of fairy tales, additional resources include phrasebooks and resources for rendering everyday phrases and concepts into Latin, such as Meissners Latin Phrasebook. The Latin influence in English has been significant at all stages of its insular development. From the 16th to the 18th centuries, English writers cobbled together huge numbers of new words from Latin and Greek words, dubbed inkhorn terms, as if they had spilled from a pot of ink. Many of these words were used once by the author and then forgotten, many of the most common polysyllabic English words are of Latin origin through the medium of Old French. Romance words make respectively 59%, 20% and 14% of English, German and those figures can rise dramatically when only non-compound and non-derived words are included. Accordingly, Romance words make roughly 35% of the vocabulary of Dutch, Roman engineering had the same effect on scientific terminology as a whole
8.
Christian Leopold von Buch
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His scientific interest was devoted to a broad spectrum of geological topics, volcanism, fossils, stratigraphy and more. His most remembered accomplishment is the definition of the Jurassic system. He was known as Leopold von Buch, Buch studied with Alexander von Humboldt under Abraham Gottlob Werner at the mining school in Freiberg, Saxony. He afterwards completed his education at the universities of Halle and Göttingen and he began writing on geological topics early in life. His Versuch einer mineralogischen Beschreibung von Landeck was translated into French, in 1802 he published Entwurf einer geognostischen Beschreibung von Schlesien, which became the first volume of his Geognostische Beobachtungen auf Reisen durch Deutschland und Italien. He was at time a zealous upholder of the Neptunian theory of Werner. In 1797, he met Humboldt at Salzburg, and with him explored the geological formations of Styria, in the spring of 1798, Buch extended his excursions into Italy, where his faith in the Neptunian theory was shaken. In his early works, he had advocated the aqueous origin of basaltic and other formations, but now he saw cause to abandon Werners theory and he saw Vesuvius for the first time in 1799. Later, in 1805, he had the opportunity, along with Humboldt and Gay Lussac and it was a remarkable eruption, and supplied Buch with data for refuting many erroneous ideas then entertained regarding volcanoes. In 1802 he examined the extinct volcanoes of the Auvergne in the south of France. The aspect of the Puy de Dôme, with its cone of trachyte and its strata of basaltic lava, the results of all these geological travels were given to the world in the two volumes of his Geognostische Beobachtungen. In 1806, Buch proceeded to Scandinavia and spent two years in examining its physical constitution and this furnished the materials for his work entitled Reise durch Norwegen und Lappland. He made many important observations on the geography of plants, on climatology and he showed that many of the erratic blocks on the North German plains must have come from Scandinavia. He also established the fact that the whole of Sweden is slowly but continuously rising above the level of the sea from Frederikshald to Abo, in 1815 Buch visited the Canary Islands in company with Christen Smith, a Norwegian botanist. These volcanic isles furnished the starting point from which Buch commenced a course of study on the production. This is attested by his work on the subject entitled Physical Description of the Canary Isles. During his time in the Canary Islands, he visited the Las Cañadas Caldera on Tenerife, when he published his memoirs and observations about his excursion, he introduced the Spanish word Caldera into the geological and scientific vocabulary. After his return from the Canaries he visited the group of the Hebrides
9.
Canary Islands
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The Canary Islands, also known as the Canaries, are an archipelago and autonomous community of Spain located on the Atlantic Ocean,100 kilometres west of Morocco. The Canaries are among the outermost regions of the European Union proper and it is also one of the eight regions with special consideration of historical nationality recognized as such by the Spanish Government. The main islands are Tenerife, Fuerteventura, Gran Canaria, Lanzarote, La Palma, La Gomera, the archipelago also includes a number of islands and islets, La Graciosa, Alegranza, Isla de Lobos, Montaña Clara, Roque del Oeste and Roque del Este. In ancient times, the chain was often referred to as the Fortunate Isles. The Canary Islands is the most southerly region of Spain and the largest and most populated archipelago of the Macaronesia region, the islands have a subtropical climate, with long hot summers and moderately warm winters. The precipitation levels and the level of maritime moderation varies depending on location and elevation, green areas as well as desert exist on the archipelago. Due to their location above the inversion layer, the high mountains of these islands are ideal for astronomical observation. For this reason, two professional observatories, Teide Observatory on the island of Tenerife and Roque de los Muchachos Observatory on the island of La Palma, have built on the islands. Las Palmas de Gran Canaria has been the largest city in the Canaries since 1768, between the 1833 territorial division of Spain and 1927 Santa Cruz de Tenerife was the sole capital of the Canary Islands. In 1927 a decree ordered that the capital of the Canary Islands be shared, the third largest city of the Canary Islands is San Cristóbal de La Laguna on Tenerife. This city is home to the Consejo Consultivo de Canarias. During the time of the Spanish Empire, the Canaries were the main stopover for Spanish galleons on their way to the Americas, who came south to catch the prevailing northeasterly trade winds. The name Islas Canarias is likely derived from the Latin name Canariae Insulae, meaning Islands of the Dogs, according to the historian Pliny the Elder, the Mauretanian king Juba II named the island Canaria because it contained vast multitudes of dogs of very large size. Another speculation is that the dogs were actually a species of monk seal, critically endangered. The dense population of seals may have been the characteristic that most struck the few ancient Romans who established contact with these islands by sea. Alternatively, it is said that the inhabitants of the island, Guanches, used to worship dogs, mummified them. The ancient Greeks also knew about a people, living far to the west, who are the dog-headed ones, who worshipped dogs on an island. Some hypothesize that the Canary Islands dog-worship and the ancient Egyptian cult of the god, Anubis are closely connected
10.
Tenerife
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Tenerife is the largest and most populated island of the seven Canary Islands. It is also the most populated island of Spain, with an area of 2,034.38 square kilometres and 898,680 inhabitants,43 percent of the total population of the Canary Islands. Tenerife is the largest and most populous island of Macaronesia, about five million tourists visit Tenerife each year, the most of any of the Canary Islands. It is one of the most important tourist destinations in Spain, Tenerife hosts one of the worlds largest carnivals and the Carnival of Santa Cruz de Tenerife is working to be designated as a UNESCO World Heritage Site. Served by two airports, Tenerife North Airport and Tenerife South Airport, Tenerife is the centre of the archipelago. The 1977 collision of two Boeing 747 passenger jets at Tenerife North Airport, resulting in 583 deaths, remains the deadliest aviation accident in world history, Santa Cruz de Tenerife is the capital of the island and the seat of the island council. The city is capital of the community of Canary Islands, sharing governmental institutions such as Presidency. Between the 1833 territorial division of Spain and 1927, Santa Cruz de Tenerife was the capital of the Canary Islands. In 1927 the Crown ordered that the capital of the Canary Islands be shared, Santa Cruz contains the modern Auditorio de Tenerife, the architectural symbol of the Canary Islands. The island is home to the University of La Laguna, founded in 1792 in San Cristóbal de La Laguna, a UNESCO World Heritage Site, the city is the second to have been founded on the island, and is the third of the archipelago. The city of La Laguna was capital of the Canary Islands before Santa Cruz replaced it in 1833, also located on the island, Macizo de Anaga since 2015 has been designated as a UNESCO Biosphere Reserve. It has the largest number of species in Europe. The islands indigenous people, the Guanches, referred to the island as Achinet or Chenet in their language. According to Pliny the Younger, Berber king Juba II sent an expedition to the Canary Islands and Madeira, he named the Canary Islands for the particularly ferocious dogs on the island. Juba II and Ancient Romans referred to the island of Tenerife as Nivaria, derived from the Latin word nix, meaning snow, the Benahoaritas are said to have named the island, deriving it from the words tene and ife. After colonisation, the Hispanisation of the resulted in adding the letter r to unite both words, producing Tenerife. He ruled the island in the days before the conquest of the Canary Islands by Castilla. The formal demonym used to refer to the people of Tenerife is Tinerfeño/a, in modern society, the latter term is generally applied only to inhabitants of the capital, Santa Cruz
11.
Teide
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Mount Teide is a volcano on Tenerife in the Canary Islands, Spain. Its 3, 718-metre summit is the highest point in Spain, if measured from the ocean floor, it is at 7,500 m the highest volcano in the world base-to-peak outside of the Hawaiian Islands. Its elevation makes Tenerife the tenth highest island in the world and it remains active, its most recent eruption occurred in 1909 from the El Chinyero vent on the northwestern Santiago rift. Teide, Pico Viejo and Montaña Blanca form the Central Volcanic Complex of Tenerife, the volcano and its surroundings comprise Teide National Park, which has an area of 18,900 hectares and was named a World Heritage Site by UNESCO on June 28,2007. Teide is the most visited natural wonder of Spain, the most visited park in Spain and Europe and – by 2015 – the eighth most visited in the world. A major international astronomical observatory is located on the slopes of the mountain, before the 1495 Spanish colonization of Tenerife, the native Guanches called the volcano Echeyde, which in their legends referred to a powerful figure leaving the volcano, which could turn into hell. El Pico del Teide is the modern Spanish name, Teide was a sacred mountain for the aboriginal Guanches, so it was considered a mythological mountain, as Mount Olympus was to the ancient Greeks. According to legend, Guayota kidnapped Magec and imprisoned him inside the volcano, the Guanches asked their supreme god Achamán for clemency, so Achamán fought Guayota, freed Magec from the bowels of the mountain, and plugged the crater with Guayota. It is said that then, Guayota has remained locked inside Teide. When going on to Teide during an eruption, it was customary for the Guanches to light bonfires to scare Guayota, Guayota is often represented as a black dog, accompanied by his host of demons. The Guanches also believed that Teide held up the sky, many hiding places found in the mountains contain the remains of stone tools and pottery. These have been interpreted as being ritual deposits to counter the influence of evil spirits, the Guanches believed the mountain to be the place that housed the forces of evil and the most evil figure, Guayota. The stratovolcanoes Teide and Pico Viejo are the most recent centres of activity on the island of Tenerife. It has a complex volcanic history, the formation of the island and the development of the current Teide volcano took place in the five stages shown in the diagram on the right. Like the other Canary Islands, and volcanic islands in general. This early shield stage volcanism formed the bulk of the part of Tenerife. The shield volcanoes date back to the Miocene and early Pliocene and are preserved in three isolated and deeply eroded massifs, Anaga, Teno and Roque del Conde, each shield was apparently constructed in less than three million years, and the entire island in about eight million years. The initial juvenile stage was followed by a period of 2–3 million years of eruptive quiescence and this cessation of activity is typical of the Canaries, La Gomera, for example, is currently at this stage
12.
Caldera de Taburiente National Park
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Caldera de Taburiente National Park is a national park on the island of La Palma, Canary Islands, Spain. It was designated as a park in 1954. The caldera is about 10 km across, and in places the walls tower 2000 m over the caldera floor, the highest point is the Roque de los Muchachos on the northern wall, at 2426 m altitude, which can be reached by road. The telescopes of the Roque de los Muchachos Observatory are situated close to the summit. It proved impregnable to the invading Spaniards, and they defeated the Benahoarita by luring their leader out on the pretext of holding talks. The Cumbrecita is at a point in the south-eastern part of the calderas rim. In the south-west the caldera opens to the sea, through a known as Barranco de las Augustias. The Cumbre Nueva is a ridge that starts at the caldera, the main flora of the national park comprises a large forest of Canary Island Pine, with important population of the endangered Canary Islands Juniper also present. The caldera originated some 2 million years ago, with a shield volcano about 20 km in diameter. The caldera was not formed by an explosion of that volcano however, the word caldera means cauldron in Spanish. In 1815 the great German geologist Christian Leopold von Buch visited the Canary Islands during which he visited the island of Tenerife where he was taken to the Caldera de las Cañadas. Following his return to Germany he published his journal and he introduced the term Caldera to the geological vocabulary, Taburiente is not a Spanish word but derives from the Guanche language and means plain, level
13.
La Palma
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La Palma, also San Miguel de La Palma, is the most north-westerly island of the Canary Islands, Spain. La Palma has an area of 706 km2 making it the fifth largest of the seven main Canary Islands. The total population is about 86,000, of which 18,000 live in the capital, Santa Cruz de la Palma, La Palma has sister city status with El Dorado Hills, California. In 1815, the German geologist Leopold von Buch visited the Canary Islands, in the center of the island is the Caldera de Taburiente National Park, one of four national parks in the Canary Islands. La Palma, like the islands of the Canary Island archipelago, is a volcanic ocean island. The volcano rises almost 7 km above the floor of the Atlantic Ocean, there is road access from sea level to the summit at 2,426 m, which is marked by an outcrop of rocks called Los Muchachos. This is the site of the Roque de los Muchachos Observatory, La Palmas geography is a result of the volcanic formation of the island. The highest peaks reach over 2,400 m above sea level, the northern part of La Palma is dominated by the Caldera de Taburiente, with a width of 9 km and a depth of 1,500 m. It is surrounded by a ring of mountains ranging from 1,600 m to 2,400 m in height, on its northern side is the exposed remains of the original seamount. Only the deep Barranco de las Angustias ravine leads into the area of the caldera. It can be reached only by hiking, the outer slopes are cut by numerous gorges which run from 2,000 m down to the sea. Today, only few of these carry water due to the water tunnels that have been cut into the islands structure. From the Caldera de Taburiente to the runs the ridge Cumbre Nueva – the New Ridge. The southern part of La Palma consists of the Cumbre Vieja, the Cumbre Vieja is active – but dormant, with the last eruption occurring in 1971 at the Teneguía vent which is located at the southern end of the Cumbre Vieja – Punta de Fuencaliente. Beyond Punta de Fuencaliente, the Cumbre Vieja continues in a direction as a submarine volcano. Like all of the Canary Islands, La Palma originally formed as a seamount through submarine volcanic activity, La Palma is currently – along with Tenerife, the most volcanically active of the Canary Islands and was formed three to four million years ago. Its base lies almost 4,000 m below sea level, about a half a million years ago, the Taburiente volcano collapsed with a giant landslide, forming the Caldera de Taburiente. Erosion has since exposed part of the seamount in the sector of the Caldera
14.
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
15.
Lake Toba
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Lake Toba is a large natural lake occupying the caldera of a supervolcano. The lake is about 100 kilometres long,30 kilometres wide and it is the largest lake in Indonesia and also the largest volcanic lake in the world. Lake Toba is the site of a massive supervolcanic eruption estimated at VEI8 that occurred 69,000 to 77,000 years ago and it is the largest known explosive eruption on Earth in the last 25 million years. It has been accepted that the eruption of Toba led to a winter with a worldwide decrease in temperature between 3 to 5 °C, and up to 15 °C in higher latitudes. The Toba caldera complex in Northern Sumatra, comprises four overlapping volcanic craters that adjoin the Sumatran volcanic front, the fourth and youngest caldera is the worlds largest Quaternary caldera and intersects the three older calderas. Following this eruption, a resurgent dome formed within the new caldera, at least four cones, four stratovolcanoes, and three craters are visible in the lake. The Tandukbenua cone on the edge of the caldera has only sparse vegetation. Also, the Pusubukit volcano on the edge of the caldera is solfatarically active and is a Geology Sanctuary. The Toba eruption occurred at what is now Lake Toba about 75000±900 years ago and it was the last in a series of at least four caldera-forming eruptions at this location, with earlier calderas having formed around 788000±2200 years ago. This last eruption had an estimated VEI=8, making it the largest known volcanic eruption within the last 25 million years. However, based on the new method, Toba possibly erupted 3200 km³ of ignimbrite and co-ignimbrite, the pyroclastic flows of the eruption destroyed an area of least 20,000 km2, with ash deposits as thick as 600 m by the main vent. In addition it has been calculated that 10,000 million tonnes of sulfurous acid or 6,000 million tonnes of sulfur dioxide were ejected into the atmosphere by the event. The subsequent collapse formed a caldera that, after filling with water, the island in the center of the lake is formed by a resurgent dome. The eruption lasted perhaps two weeks, and the ensuing volcanic winter resulted in a decrease in global temperatures by 3.0 to 3.5 °C for several years. Greenland ice cores record a pulse of starkly reduced levels of carbon sequestration. Very few plants or animals in southeast Asia would have survived, however, the global cooling has been discussed by Rampino and Self. Their conclusion is that the cooling had already started before Tobas eruption and this conclusion was supported by Lane and Zielinski who studied the lake-core from Africa and GISP2. They concluded that there was no volcanic winter after Toba eruption, however, this hypothesis is not widely accepted because similar effects on other animal species have not been observed, and paleoanthropology suggests there was no population bottleneck
16.
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
17.
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
18.
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
19.
Volcano
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A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Earths volcanoes occur because its crust is broken into 17 major, therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging. This type of volcanism falls under the umbrella of plate hypothesis volcanism, Volcanism away from plate boundaries has also been explained as mantle plumes. These so-called hotspots, for example Hawaii, are postulated to arise from upwelling diapirs with magma from the boundary,3,000 km deep in the Earth. Volcanoes are usually not created where two plates slide past one another. Erupting volcanoes can pose hazards, not only in the immediate vicinity of the eruption. Historically, so-called volcanic winters have caused catastrophic famines, the word volcano is derived from the name of Vulcano, a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan, the god of fire in Roman mythology. The study of volcanoes is called volcanology, sometimes spelled vulcanology, at the mid-oceanic ridges, two tectonic plates diverge from one another as new oceanic crust is formed by the cooling and solidifying of hot molten rock. Most divergent plate boundaries are at the bottom of the oceans, therefore, most volcanic activity is submarine, black smokers are evidence of this kind of volcanic activity. Where the mid-oceanic ridge is above sea-level, volcanic islands are formed, for example, subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. In this case, the plate subducts, or submerges under the continental plate forming a deep ocean trench just offshore. In a process called flux melting, water released from the subducting plate lowers the temperature of the overlying mantle wedge. This magma tends to be very viscous due to its high content, so it often does not reach the surface. When it does reach the surface, a volcano is formed, typical examples of this kind of volcano are Mount Etna and the volcanoes in the Pacific Ring of Fire. Because tectonic plates move across them, each volcano becomes dormant and is eventually re-formed as the plate advances over the postulated plume and this theory is currently under criticism, however. The most common perception of a volcano is of a mountain, spewing lava and poisonous gases from a crater at its summit, however. The features of volcanoes are more complicated and their structure. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have features such as massive plateaus
20.
1815 eruption of Mount Tambora
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The 1815 eruption of Mount Tambora was one of the most powerful eruptions in recorded history and is the most recent known VEI-7 event. The eruption column lowered global temperatures, and some believe this led to global cooling. The eruption resulted in a period of significant climate change that led to various cases of extreme weather. Several climate forcings coincided and interacted in a manner that has not been observed since. Although the link between the climate changes and the Tambora event has been established by various scientists, the understanding of the processes involved is incomplete. Mount Tambora experienced several centuries of dormancy before 1815, as the result of the cooling of hydrous magma in a closed magma chamber. Inside the chamber at depths between 1.5 and 4.5 km, the exsolution of a high-pressure fluid magma formed during cooling, overpressure of the chamber of about 4, 000–5,000 bar was generated, and the temperature ranged from 700 to 850 °C. In 1812, the volcano began to rumble and generated a dark cloud, on the morning of 6 April, volcanic ash began to fall in East Java with faint detonation sounds lasting until 10 April. What was first thought to be the sound of firing guns was heard on 10 April on Sumatra more than 2,600 km away, at about 7 pm on 10 April, the eruptions intensified. Three columns of flame rose up and merged, the whole mountain was turned into a flowing mass of liquid fire. Pumice stones of up to 20 cm in diameter started to rain down around 8 pm, pyroclastic flows cascaded down the mountain to the sea on all sides of the peninsula, wiping out the village of Tambora. Loud explosions were heard until the evening,11 April. The ash veil had spread as far as West Java and South Sulawesi, a nitrous odour was noticeable in Batavia and heavy tephra-tinged rain fell, finally receding between 11 and 17 April. The first explosions were heard on this Island in the evening of 5 April, they were noticed in every quarter, the explosion is estimated to have been a VEI-7. An estimated 41 km3 of pyroclastic trachyandesite were ejected, weighing about 10 billion tonnes and this has left a caldera measuring 6–7 km across and 600–700 m deep. The density of ash in Makassar was 636 kg/m³. Before the explosion, Mount Tambora was about 4,300 m high, after the explosion, it measured only 2,851 m. The 1815 Tambora eruption is the largest observed eruption in recorded history, the explosion was heard 2,600 km away, and ash fell at least 1,300 km away
21.
Piton de la Fournaise
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Piton de la Fournaise, Peak of the Furnace is a shield volcano on the eastern side of Réunion island in the Indian Ocean. It is currently one of the most active volcanoes in the world, along with Kīlauea in the Hawaiian Islands, Stromboli, Etna, a previous eruption began in August 2006 and ended in January 2007. The volcano erupted again in February 2007, on 21 September 2008, on 9 December 2010, the most recent eruption began on 31 January 2017. The volcano is located within Réunion National Park, a World Heritage site, Piton de la Fournaise is often known locally as le Volcan, it is a major tourist attraction on Réunion island. The top part of the volcano is occupied by the Enclos Fouqué, high cliffs known as remparts form the calderas rim. The caldera is breached to the southeast into the sea and it is unstable and is in the initial stages of failure. It will eventually collapse into the Indian Ocean, whether it will generate a so-called megatsunami is controversial. There is evidence on the flanks and abyssal plain of earlier failures. The lower slopes are known as the Grand Brûlé, most volcanic eruptions are confined to the caldera. Inside the caldera is a 400 meter high lava shield known as Dolomieu, atop the lava shield are Bory Crater and Dolomieu Crater, named for French geologist Déodat Gratet de Dolomieu, which is by far the wider of the two. Many craters and spatter cones can be found inside the caldera, at the beginning of the path that leads to the summit, there lies a noticeable small crater known as Formica Leo, named for its similar shape to the pitfall built by the antlion. Some of the beaches there are of a colour, because of the olivine sand resulting from picrite basalt lavas. Iridium is being ejected through these vents, there were three episodes of caldera collapses 250,000,65,000 and 5,000 years ago. The volcano was formed by the Réunion hotspot, which is believed to have been active for the past 66 million years, there is evidence for explosive eruptions in the past. One explosive eruption about 4,700 years ago may have had a VEI of 5, most eruptions of Piton de la Fournaise are of the Hawaiian style, fluid basaltic lava flowing out with fire fountaining at the vent. Lava flows crossing the Grand Brûlé occasionally reach the sea, with spectacular results, Piton de la Fournaise is one of the most active volcanoes in the world, with more than 150 recorded eruptions since the 17th century. Eruptions within the caldera do not cause much devastation, because the caldera is uninhabited, lava flows are generally confined to the caldera. However, lava flows have been known to cross the N2 highway, in the early 2000s, the highway thus was destroyed once or more times a year, road engineering services then wait for the lava to cool off and build another stretch of road
22.
Magma
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Besides molten rock, magma may also contain suspended crystals, dissolved gas and sometimes gas bubbles. Magma often collects in magma chambers that may feed a volcano or solidify underground to form an intrusion, magma is capable of intruding into adjacent rocks, extrusion onto the surface as lava, and explosive ejection as tephra to form pyroclastic rock. Magma is a complex high-temperature fluid substance, temperatures of most magmas are in the range 700 °C to 1300 °C, but very rare carbonatite magmas may be as cool as 600 °C, and komatiite magmas may have been as hot as 1600 °C. Environments of magma formation and compositions are commonly correlated, environments include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Despite being found in such locales, the bulk of the Earths crust. Except for the outer core, most of the Earth takes the form of a rheid. Magma, as liquid, preferentially forms in high temperature, low pressure environments within several kilometers of the Earths surface, magma compositions may evolve after formation by fractional crystallization, contamination, and magma mixing. By definition rock formed of solidified magma is called igneous rock, melting of solid rocks to form magma is controlled by three physical parameters, temperature, pressure, and composition. Mechanisms are discussed in the entry for igneous rock, as a rock melts, its volume changes. When enough rock is melted, the small globules of melt link up, under pressure within the earth, as little as a fraction of a percent partial melting may be sufficient to cause melt to be squeezed from its source. The degree of melting is critical for determining what type of magma is produced. The degree of partial melting required to form a melt can be estimated by considering the relative enrichment of incompatible elements versus compatible elements, incompatible elements commonly include potassium, barium, cesium, and rubidium. Rock types produced by small degrees of melting in the Earths mantle are typically alkaline. Typically, primitive melts of this composition form lamprophyre, lamproite, kimberlite and sometimes nepheline-bearing mafic rocks such as alkali basalts, pegmatite may be produced by low degrees of partial melting of the crust. Some granite-composition magmas are eutectic melts, and they may be produced by low to high degrees of melting of the crust. At high degrees of melting of the crust, granitoids such as tonalite, granodiorite and monzonite can be produced. Being only the time in recorded history that magma had been reached, IDDP decided to invest in the hole. A cemented steel case was constructed in the hole with a perforation at the close to the magma
23.
Fracture (geology)
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A fracture is any separation in a geologic formation, such as a joint or a fault that divides the rock into two or more pieces. A fracture will form a deep fissure or crevice in the rock. Fractures are commonly caused by exceeding the rock strength, causing the rock to lose cohesion along its weakest plane. Fractures can provide permeability for fluid movement, such as water or hydrocarbons, highly fractured rocks can make good aquifers or hydrocarbon reservoirs, since they may possess both significant permeability and fracture porosity. Fractures are forms of brittle deformation, there are two types of primary brittle deformation processes. Shear fractures are the first initial breaks resulting from shear forces exceeding the strength in that plane. After those two initial deformations, several types of secondary brittle deformation can be observed, such as frictional sliding or cataclastic flow on reactivated joints or faults. Most often, fracture profiles will look like either a blade, ellipsoid, Fractures in rocks can be formed either due to compression or tension. Fractures due to include thrust faults. Fractures may also be a result from shear or tensile stress, some of the primary mechanisms are discussed below. First, there are three modes of fractures occur, Mode I crack – Opening mode Mode II crack – Sliding mode Mode III crack – Tearing mode For more information on this. This deformation creates propagation of fractures into previously unfractured rock, when the rock is subjected to tensile stress, in the case of a homogenous stress field, the crack will propagate in the direction perpendicular to the least principal stress. Engineers studying elasticity found that the due to a load distant from the region of interest is concentrated around material flaws. A. W. Griffith took this example and applied the concept of stress concentration to the ends of fractures, Griffith asserted that all material have microcracks or flaws where the stress concentration naturally occurs, and that these were the flaws where, under increasing stress, fractures propagate. As a result, these flaws were named Griffith cracks. From this assumption, tensile fracture development may be examined, the first form is in axial stretching. In this case, remote tensile stress is applied, allowing microcracks to open throughout the tensile region. As these cracks open up, the stresses at the crack tips intensify, eventually exceeding the rock strength and this can occur at times of rapid overburden erosion
24.
Intrusive rock
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Intrusive rock is formed when magma crystallizes and solidifies underground to form intrusions, for example plutons, batholiths, dikes, sills, laccoliths, and volcanic necks. Intrusive rock forms within Earths crust from the crystallization of magma, magma slowly pushes up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the magma slowly cools into a solid, the different parts of the magma crystallize into rocks, many mountain ranges, such as the Sierra Nevada in California, are formed mostly from large granite intrusions, see Sierra Nevada Batholith. Intrusions are one of the two ways igneous rock can form, the other is extrusive rock, that is, an eruption or similar event. Technically speaking, an intrusion is any formation of igneous rock, rock formed from magma that cools. In contrast, an extrusion consists of rock, rock formed above the surface of the crust. Large bodies of magma that solidify underground before they reach the surface of the crust are called plutons, plutonic rocks form 7% of the Earths current land surface. Coarse-grained intrusive igneous rocks form at depth within the earth are called abyssal while those that form near the surface are called subvolcanic or hypabyssal. The term intrusive suite seems near synonymous, there is, however, a modest difference, An intrusive suite is a group of plutons related in time and space. Intrusions vary widely, from mountain-range-sized batholiths to thin veinlike fracture fillings of aplite or pegmatite, when exposed by erosion, such batholiths may occupy large areas. A well-known example of an intrusion is Devils Tower, another is Shiprock, New Mexico, USA. Be the pluton is large, it may be called a batholith or a stock, Intrusive rocks are characterized by large crystal sizes, and as the individual crystals are visible, the rock is called phaneritic. This is as the magma cools underground, and while cooling may be fast or slow, cooling is slower than on the surface, if it runs parallel to rock layers, it is called a sill. If an intrusion makes rocks above rise to form a dome, as heat dissipation is slow, and as the rock is under pressure, crystals form, and no vitreous rapidly chilled matter is present. The intrusions did not flow while solidifying, hence do not show lines, contained gases could not escape through the thick strata, thus form cavities, which can often be observed. Because their crystals are of the rough equal size, these rocks are said to be equigranular, there is typically no distinction between a first generation of large well-shaped crystals and a fine-grained ground-mass. Earlier crystals originated at a time when most of the rock was still liquid and are more or less perfect, later crystals are less regular in shape because they were compelled to occupy the spaces left between the already-formed crystals. The former case is said to be idiomorphic, the latter is xenomorphic, there are also many other characteristics that serve to distinguish the members of these two groups
25.
Ore deposit
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An ore is a type of rock that contains sufficient minerals with important elements including metals that can be economically extracted from the rock. The ores are extracted from the earth through mining, they are refined to extract the valuable element. The grade or concentration of an ore mineral, or metal, as well as its form of occurrence, will directly affect the costs associated with mining the ore. The cost of extraction must thus be weighed against the value contained in the rock to determine what ore can be processed. Metal ores are generally oxides, sulfides, silicates, or native metals that are not commonly concentrated in the Earths crust, the ores must be processed to extract the metals of interest from the waste rock and from the ore minerals. Ore bodies are formed by a variety of geological processes, the process of ore formation is called ore genesis. An ore deposit is an accumulation of ore and this is distinct from a mineral resource as defined by the mineral resource classification criteria. An ore deposit is one occurrence of a particular ore type, Ore deposits are classified according to various criteria developed via the study of economic geology, or ore genesis. Stratiform arkose-hosted and shale-hosted copper, typified by the Zambian copperbelt and this identifies, early on, whether further investment in estimation and engineering studies is warranted and identifies key risks and areas for further work. This is because the distribution of ores is unequal and dislocated from locations of peak demand. Other, lesser, commodities do not have international clearing houses and benchmark prices and this generally makes determining the price of ores of this nature opaque and difficult. Such metals include lithium, niobium-tantalum, bismuth, antimony and rare earths, most of these commodities are also dominated by one or two major suppliers with >60% of the worlds reserves. The London Metal Exchange aims to add uranium to its list of metals on warrant, the World Bank reports that China was the top importer of ores and metals in 2005 followed by the USA and Japan. Economic geology Mineral resource classification Ore genesis Petrology Froth Flotation Extractive metallurgy DILL, the “chessboard” classification scheme of mineral deposits, Mineralogy and geology from aluminum to zirconium, Earth-Science Reviews, Volume 100, Issue 1-4, June 2010, Pages 1-420
26.
Northwestern Ontario
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Northwestern Ontario is a secondary region of Northern Ontario which lies north and west of Lake Superior, and west of Hudson Bay and James Bay. It includes most of subarctic Ontario and its western boundary is the Canadian province of Manitoba, which disputed Ontarios claim to the western part of the region. Ontarios right to Northwestern Ontario was determined by the Judicial Committee of the Privy Council in 1884, for some purposes, Northwestern Ontario and Northeastern Ontario are treated as separate regions, while for other purposes they are grouped together as Northern Ontario. Northwestern Ontario consists of the districts of Kenora, Rainy River and Thunder Bay, major communities in the region include Thunder Bay, Kenora, Dryden, Fort Frances, Sioux Lookout, Greenstone, Red Lake, Marathon, and Atikokan. There are also several dozen First Nations in Northwestern Ontario, Northwestern Ontario is divided between the Eastern Time Zone and the Central Time Zone. Northwestern Ontario is the provinces most sparsely populated region —54 per cent of the entire population lives in the Thunder Bay census metropolitan area alone. Aside from the city of Thunder Bay, Kenora is the other municipality in the entire region with a population of greater than 10,000 people. Northwestern Ontarians tend to lean left politically, mainly due to the history and influence of unions, a growing environmental ethic. At the federal level, Northwestern Ontario is represented by Liberal MPs Bob Nault in the Kenora District, Don Rusnak in Thunder Bay—Rainy River, provincially, NDP Sarah Campbell represents Kenora—Rainy River while Liberals Bill Mauro and Michael Gravelle represent Thunder Bay—Atikokan and Thunder Bay—Superior North respectively. In 2005, some residents of the region expressed dissatisfaction at the level of attention paid to the region by the provincial government, Northern Ontario Northeastern Ontario Gateway to Northwestern Ontario History
27.
Explosive eruption
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An explosive eruption is a volcanic term to describe a violent, explosive type of eruption. Mount St. Helens in 1980 was an example, such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent. Sometimes a lava plug will block the conduit to the summit, Explosive eruptions can send rocks, dust, gas and pyroclastic material up to 20 km into the atmosphere at rate of up to 100,000 tonnes per second, traveling at several hundred meters per second. This cloud will collapse, creating a pyroclastic flow of hot volcanic matter. An explosive eruption always begins with some form of blockage in the crater of a volcano that prevents the release of trapped in highly viscous andesitic or rhyolitic magma. The high viscosity of these forms of magma prevents the release of trapped gases, when this type of magma flows towards the surface pressure builds, eventually causing the blockage to be blasted out in an explosive eruption. The pressure from the magma and gases are released through the weakest point in the cone, however, in the case of the eruption of Mount St. Helens, pressure was released through the side of the volcano, rather than the crater. The size and duration of the column depends on the volume of magma being released, the eruption column of ash is supported by pressure from the gases being released, and as the gases are depleted, pressure falls and the eruption column begins to collapse. When the column collapses in on itself, ash and rock fall back down to the ground and these flows can travel at up to 80 km per hour, and reach temperatures of 200° to 700° Celsius. The high temperatures can cause combustion of any flammable materials in its path, including wood, vegetation, when snow and ice melt as a part of an eruption, large amounts of water mixed in with the flow can create lahars. The risk of lahars is particularly high on volcanoes such as Mount Rainier near Seattle and Tacoma, the eruption of supervolcanoes is the rarest of volcanic eruptions but also the most destructive. The timescale between these eruptions is generally marked by hundreds or thousands of years and this type of eruption generally causes destruction on a continental scale, and can also result in the lowering of temperatures worldwide. Effusive eruption Volcanic explosivity index Recent Developments in Explosive Volcanism
28.
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
29.
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
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Rhyolite
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Rhyolite is an igneous, volcanic rock, of felsic composition. It may have any texture from glassy to aphanitic to porphyritic, the mineral assemblage is usually quartz, sanidine and plagioclase. Biotite and hornblende are common accessory minerals and it is the extrusive equivalent to granite. Rhyolite can be considered as the equivalent to the plutonic granite rock. Due to their content of silica and low iron and magnesium contents, rhyolite melts are highly polymerized. They also occur as breccias or in volcanic plugs and dikes, rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian. Slower cooling forms microscopic crystals in the lava and results in such as flow foliations, spherulitic, nodular. Some rhyolite is highly vesicular pumice, many eruptions of rhyolite are highly explosive and the deposits may consist of fallout tephra/tuff or of ignimbrites. Eruptions of rhyolite are relatively rare compared to eruptions of less felsic lavas, etsch Valley Vulcanite Group near Bolzano and the surrounding area Gréixer rhyolitic complex at Moixeró range Vosges Iceland, all active and extinct central volcanoes, e. g. g. Wichita Mountains within the Southern Oklahoma Aulacogen St, in North American pre-historic times, rhyolite was quarried extensively in eastern Pennsylvania in the United States. Among the leading quarries was the Carbaugh Run Rhyolite Quarry Site in Adams County, comendite List of rock types Pantellerite Thunderegg University of North Dakota description of rhyolite Information from rocks-rock. com
31.
Igneous rock
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Igneous rock, or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava, the magma can be derived from partial melts of existing rocks in either a planets mantle or crust. Typically, the melting is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, Igneous and metamorphic rocks make up 90–95% of the top 16 km of the Earths crust by volume. Igneous rocks form about 15% of the Earths current land surface, most of the Earths oceanic crust is made of igneous rock. In terms of modes of occurrence, igneous rocks can be either intrusive or extrusive, the mineral grains in such rocks can generally be identified with the naked eye. Intrusive rocks can also be classified according to the shape and size of the intrusive body, typical intrusive formations are batholiths, stocks, laccoliths, sills and dikes. When the magma solidifies within the earths crust, it cools slowly forming coarse textured rocks, such as granite, gabbro, the central cores of major mountain ranges consist of intrusive igneous rocks, usually granite. When exposed by erosion, these cores may occupy huge areas of the Earths surface, intrusive igneous rocks that form at depth within the crust are termed plutonic rocks and are usually coarse-grained. Intrusive igneous rocks that form near the surface are termed subvolcanic or hypabyssal rocks, hypabyssal rocks are less common than plutonic or volcanic rocks and often form dikes, sills, laccoliths, lopoliths, or phacoliths. Extrusive igneous rocks, also known as rocks, are formed at the crusts surface as a result of the partial melting of rocks within the mantle. Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks and they are formed by the cooling of molten magma on the earths surface. The magma, which is brought to the surface through fissures or volcanic eruptions, hence such rocks are smooth, crystalline and fine-grained. Basalt is an extrusive igneous rock and forms lava flows, lava sheets. Some kinds of basalt solidify to form long polygonal columns, the Giants Causeway in Antrim, Northern Ireland is an example. The molten rock, with or without suspended crystals and gas bubbles, is called magma and it rises because it is less dense than the rock from which it was created. When magma reaches the surface from beneath water or air, it is called lava, eruptions of volcanoes into air are termed subaerial, whereas those occurring underneath the ocean are termed submarine. Black smokers and mid-ocean ridge basalt are examples of volcanic activity
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Viscosity
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The viscosity of a fluid is a measure of its resistance to gradual deformation by shear stress or tensile stress. For liquids, it corresponds to the concept of thickness, for example. Viscosity is a property of the fluid which opposes the motion between the two surfaces of the fluid in a fluid that are moving at different velocities. For a given velocity pattern, the stress required is proportional to the fluids viscosity, a fluid that has no resistance to shear stress is known as an ideal or inviscid fluid. Zero viscosity is observed only at low temperatures in superfluids. Otherwise, all fluids have positive viscosity, and are said to be viscous or viscid. A fluid with a high viscosity, such as pitch. The word viscosity is derived from the Latin viscum, meaning mistletoe, the dynamic viscosity of a fluid expresses its resistance to shearing flows, where adjacent layers move parallel to each other with different speeds. It can be defined through the situation known as a Couette flow. This fluid has to be homogeneous in the layer and at different shear stresses, if the speed of the top plate is small enough, the fluid particles will move parallel to it, and their speed will vary linearly from zero at the bottom to u at the top. Each layer of fluid will move faster than the one just below it, in particular, the fluid will apply on the top plate a force in the direction opposite to its motion, and an equal but opposite one to the bottom plate. An external force is required in order to keep the top plate moving at constant speed. The magnitude F of this force is found to be proportional to the u and the area A of each plate. The proportionality factor μ in this formula is the viscosity of the fluid, the ratio u/y is called the rate of shear deformation or shear velocity, and is the derivative of the fluid speed in the direction perpendicular to the plates. Isaac Newton expressed the forces by the differential equation τ = μ ∂ u ∂ y, where τ = F/A. This formula assumes that the flow is moving along parallel lines and this equation can be used where the velocity does not vary linearly with y, such as in fluid flowing through a pipe. Use of the Greek letter mu for the dynamic viscosity is common among mechanical and chemical engineers. However, the Greek letter eta is used by chemists, physicists
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Basalt
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Basalt is a common extrusive igneous rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon. Flood basalt describes the formation in a series of basalt flows. By definition, basalt is an igneous rock with generally 45-55% silica and less than 10% feldspathoid by volume. Basalt commonly features a very fine-grained or glassy matrix interspersed with visible mineral grains, the average density is 3.0 gm/cm3. Basalt is defined by its content and texture, and physical descriptions without mineralogical context may be unreliable in some circumstances. Basalt is usually grey to black in colour, but rapidly weathers to brown or rust-red due to oxidation of its mafic minerals into hematite, although usually characterized as dark, basaltic rocks exhibit a wide range of shading due to regional geochemical processes. Due to weathering or high concentrations of plagioclase, some basalts can be quite light-coloured and these phenocrysts usually are of olivine or a calcium-rich plagioclase, which have the highest melting temperatures of the typical minerals that can crystallize from the melt. Basalt with a texture is called vesicular basalt, when the bulk of the rock is mostly solid. Gabbro is often marketed commercially as black granite and these ultramafic volcanic rocks, with silica contents below 45% are usually classified as komatiites. Agricola applied basalt to the black rock of the Schloßberg at Stolpen. Tholeiitic basalt is relatively rich in silica and poor in sodium, included in this category are most basalts of the ocean floor, most large oceanic islands, and continental flood basalts such as the Columbia River Plateau. Basalt rocks are in some cases classified after their content in High-Ti and Low-Ti varieties. High-Ti and Low-Ti basalts have been distinguished in the Paraná and Etendeka traps and it has greater than 17% alumina and is intermediate in composition between tholeiite and alkali basalt, the relatively alumina-rich composition is based on rocks without phenocrysts of plagioclase. Alkali basalt is relatively poor in silica and rich in sodium and it is silica-undersaturated and may contain feldspathoids, alkali feldspar and phlogopite. Boninite is a form of basalt that is erupted generally in back-arc basins. Ocean island basalt Lunar basalt On Earth, most basalt magmas have formed by melting of the mantle. Basalt commonly erupts on Io, the third largest moon of Jupiter, and has formed on the Moon, Mars, Venus. The crustal portions of oceanic tectonic plates are composed predominantly of basalt, produced from upwelling mantle below, the mineralogy of basalt is characterized by a preponderance of calcic plagioclase feldspar and pyroxene
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Volcanic ash
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Volcanic ash consists of fragments of pulverized rock, minerals and volcanic glass, created during volcanic eruptions and measuring less than 2 mm in diameter. The term volcanic ash is often loosely used to refer to all explosive eruption products. Volcanic ash is formed during volcanic eruptions when dissolved gases in magma expand. The force of the escaping gas shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, once in the air, ash is transported by wind up to thousands of kilometers away. Volcanic ash is formed during volcanic eruptions, phreatomagmatic eruptions. Explosive eruptions occur when magma decompresses as it rises, allowing dissolved volatiles to exsolve into gas bubbles, as more bubbles nucleate a foam is produced, which decreases the density of the magma, accelerating it up the conduit. Fragmentation occurs when bubbles occupy ~70-80 vol% of the erupting mixture, when fragmentation occurs, violently expanding bubbles tear the magma apart into fragments which are ejected into the atmosphere where they solidify into ash particles. Fragmentation is an efficient process of ash formation and is capable of generating very fine ash even without the addition of water. Volcanic ash is produced during phreatomagmatic eruptions. During these eruptions fragmentation occurs when magma comes into contact with bodies of water groundwater, as the magma, which is significantly hotter than the boiling point of water, comes into contact with water an insulating vapor film forms. Eventually this vapor film will collapse leading to direct coupling of the cold water and this increases the heat transfer which leads to the rapid expansion of water and fragmentation of the magma into small particles which are subsequently ejected from the volcanic vent. Fragmentation causes an increase in area between magma and water creating a feedback mechanism, leading to further fragmentation and production of fine ash particles. Pyroclastic density currents can also produce ash particles and these are typically produced by lava dome collapse or collapse of the eruption column. Within pyroclastic density currents particle abrasion occurs as particles interact with each resulting in a reduction in grain size. In addition, ash can be produced during secondary fragmentation of pumice fragments and these processes produce large quantities of very fine grained ash which is removed from pyroclastic density currents in co-ignimbrite ash plumes. Physical and chemical characteristics of volcanic ash are primarily controlled by the style of volcanic eruption, another parameter controlling the amount of ash produced is the duration of the eruption, the longer the eruption is sustained, the more ash will be produced. The types of minerals present in volcanic ash are dependent on the chemistry of the magma from which it erupted, low energy eruptions of basalt produce a characteristically dark coloured ash containing ~45 - 55% silica that is generally rich in iron and magnesium
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Lava
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Lava is the molten rock expelled by a volcano during an eruption. The resulting rock after solidification and cooling is called lava. The molten rock is formed in the interior of planets, including Earth. The source of the heat melts the rock within the earth is geothermal energy. When first erupted from a vent, lava is a liquid usually at temperatures from 700 to 1,200 °C. A lava flow is an outpouring of lava, which is created during a non-explosive effusive eruption. When it has stopped moving, lava solidifies to form igneous rock, the term lava flow is commonly shortened to lava. Although lava can be up to 100,000 times more viscous than water, lava can flow great distances before cooling and solidifying because of its thixotropic, explosive eruptions produce a mixture of volcanic ash and other fragments called tephra, rather than lava flows. The word lava comes from Italian, and is derived from the Latin word labes which means a fall or slide. The first use in connection with extruded magma was apparently in an account written by Francesco Serao on the eruption of Vesuvius between May 14 and June 4,1737. Serao described a flow of lava as an analogy to the flow of water. The composition of almost all lava of the Earths crust is dominated by silicate minerals, mostly feldspars, olivine, pyroxenes, amphiboles, micas, igneous rocks, which form lava flows when erupted, can be classified into three chemical types, felsic, intermediate, and mafic. These classes are primarily chemical, however, the chemistry of lava also tends to correlate with the temperature, its viscosity. Felsic or silicic lavas such as rhyolite and dacite typically form lava spines, most silicic lava flows are extremely viscous, and typically fragment as they extrude, producing blocky autobreccias. Felsic magmas can erupt at temperatures as low as 650 to 750 °C, unusually hot rhyolite lavas, however, may flow for distances of many tens of kilometres, such as in the Snake River Plain of the northwestern United States. Intermediate or andesitic lavas are lower in aluminium and silica, and usually somewhat richer in magnesium, intermediate lavas form andesite domes and block lavas, and may occur on steep composite volcanoes, such as in the Andes. Poorer in aluminium and silica than felsic lavas, and also commonly hotter, greater temperatures tend to destroy polymerized bonds within the magma, promoting more fluid behaviour and also a greater tendency to form phenocrysts. Higher iron and magnesium tends to manifest as a darker groundmass, mafic or basaltic lavas are typified by their high ferromagnesian content, and generally erupt at temperatures in excess of 950 °C
36.
Yellowstone Caldera
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The Yellowstone Caldera is a volcanic caldera and supervolcano located in Yellowstone National Park in the United States, sometimes referred to as the Yellowstone Supervolcano. The caldera and most of the park are located in the northwest corner of Wyoming, the major features of the caldera measure about 34 by 45 miles. The source of the Yellowstone hotspot is controversial, some geoscientists hypothesize that the Yellowstone hotspot is the effect of an interaction between local conditions in the lithosphere and upper mantle convection. Others suggest a deep mantle origin, part of the controversy is the relatively sudden appearance of the hotspot in the geologic record. Additionally, the Columbia Basalt flows appeared at the approximate time. Volcanism at Yellowstone is relatively recent with calderas that were created during large eruptions that took place 2.1 million,1.3 million, the calderas lie over a hotspot where light, hot, molten rock from the mantle rises toward the surface. While the Yellowstone hotspot is now under the Yellowstone Plateau, it helped create the eastern Snake River Plain through a series of huge volcanic eruptions. Over the past 18 million years or so, this hotspot has generated a succession of violent eruptions, together these eruptions have helped create the eastern part of the Snake River Plain from a once-mountainous region. At least a dozen of these eruptions were so massive that they are classified as supereruptions, volcanic eruptions sometimes empty their stores of magma so swiftly that they cause the overlying land to collapse into the emptied magma chamber, forming a geographic depression called a caldera. The loosely defined term supervolcano has been used to describe volcanic fields that produce exceptionally large volcanic eruptions. The three supereruptions occurred 2.1 million,1.3 million, and approximately 630,000 years ago, forming the Island Park Caldera, the Henrys Fork Caldera, and Yellowstone calderas, respectively. The Island Park Caldera supereruption, which produced the Huckleberry Ridge Tuff, was the largest, the next biggest supereruption formed the Yellowstone Caldera and produced the Lava Creek Tuff. The Henrys Fork Caldera produced the smaller Mesa Falls Tuff but is the caldera from the Snake River Plain-Yellowstone hotspot that is plainly visible today. Non-explosive eruptions of lava and less-violent explosive eruptions have occurred in, the most recent lava flow occurred about 70,000 years ago, while a violent eruption excavated the West Thumb of Lake Yellowstone around 150,000 years ago. Smaller steam explosions occur as well, an explosion 13,800 years ago left a 5 km diameter crater at Mary Bay on the edge of Yellowstone Lake. The volcanic eruptions, as well as the geothermal activity, are a result of a great cove of magma located below the calderas surface. The magma in this cove contains gases that are dissolved by the immense pressure that the magma is under. If the pressure is released to a sufficient degree by some geological shift, then some of the bubble out
37.
Krakatoa
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Krakatoa, or Krakatau, is a volcanic island situated in the Sunda Strait between the islands of Java and Sumatra in the Indonesian province of Lampung. The explosion is considered to be the loudest sound heard in modern history. The shock waves from the explosion were recorded on barographs worldwide for days afterward, in 1927 a new island, Anak Krakatau, or Child of Krakatoa, emerged from the caldera formed in 1883 and is the current location of eruptive activity. The most notable eruptions of Krakatoa culminated in a series of explosions over August 26–27,1883. The 1883 eruption ejected approximately 25 km3 of rock, the cataclysmic explosion was heard 4,800 km away in Alice Springs, as well as on the island of Rodrigues near Mauritius,4,653 km to the west. According to the records of the Dutch East Indies colony,165 villages and towns were destroyed near Krakatoa. At least 36,417 people died, and many thousands were injured. The eruption destroyed two-thirds of the island of Krakatoa, eruptions in the area since 1927 have built a new island at the same location, named Anak Krakatau. Periodic eruptions have continued since, with recent eruptions in 2009,2010,2011, as of late 2011, this island has a radius of roughly 2 kilometres, and a high point of about 324 metres above sea level, growing 5 metres each year. About two dozen variants have found, including Crackatouw, Cracatoa, and Krakatao. The first known appearance of the spelling Krakatau was by Wouter Schouten, the origin of the Indonesian name Krakatau is uncertain. The Smithsonian Institutions Global Volcanism Program cites the Indonesian name, Krakatau, as the correct name, while Krakatoa is more common in the English-speaking world, the Indonesian Krakatau tends to be favored by others, including geologists. Indonesia has over 130 active volcanoes, the most of any nation and they make up the axis of the Indonesian island arc system, which was produced by northeastward subduction of the Indo-Australian Plate. A majority of volcanoes lie along Indonesias two largest islands, Java and Sumatra. These two islands are separated by the Sunda Strait, which is located at a bend in the axis of the island arc. At some point in prehistory, an earlier caldera-forming eruption had occurred, leaving as remnants Verlaten, Lang, Poolsche Hoed, later, at least two more cones formed and eventually joined with Rakata, forming the main island of Krakatoa. At the time of the 1883 eruption, the Krakatoa group comprised Lang, Verlaten, and Krakatoa itself, there were also the tree-covered islet near Lang and several small rocky islets or banks between Krakatoa and Verlaten. There were three volcanic cones on Krakatoa island, Rakata, to the south, Danan, near the center, and Perboewatan, to the north
38.
Mount Pinatubo
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Its eruptive history was unknown to most before the pre-eruption volcanic activities of 1991, just before June. Pinatubo was heavily eroded, inconspicuous and obscured from view and it was covered with dense forests which supported a population of several thousand indigenous Aetas. The volcanos Ultra Plinian eruption on June 15,1991 produced the second-largest terrestrial eruption of the 20th century after the 1912 eruption of Novarupta in the Alaska Peninsula. Complicating the eruption was the arrival of Typhoon Yunya, bringing a lethal mix of ash and rain to towns. Predictions at the onset of the eruption led to the evacuation of tens of thousands of people from the surrounding areas. Surrounding areas were damaged by pyroclastic surges, ash falls. This caused extensive destruction to infrastructure and changed river systems for years after the eruption, the effects of the eruption were felt worldwide. It ejected roughly 10,000,000,000 tonnes or 10 km3 of magma and it injected more particulate into the stratosphere than any eruption since Krakatoa in 1883. Over the following months, the aerosols formed a layer of sulfuric acid haze. Global temperatures dropped by about 0.5 °C in the years 1991–93, the volcano is 87 km northwest of Manila, the capital of the Philippines. Near Mount Pinatubo, the United States maintained two military bases in the region. The U. S. Naval Base Subic Bay was 37 km south of Pinatubo, the volcano is near to about 6 million people. It is part of a chain of volcanoes lie along the western side of the edge of the island of Luzon called the Zambales Mountains. Pinatubo belongs to the Cabusilan sub-range of the Zambales Mountains, which consists of Mt. Cuadrado, Mt. Negron, Mt. Mataba and they are subduction volcanoes, formed by the Eurasian Plate sliding under the Philippine Mobile Belt along the Manila Trench to the west. Mount Pinatubo and the volcanoes on this volcanic belt arise due to magmatic occlusion from this subduction plate boundary. Pinatubo is flanked on the west by the Zambales Ophiolite Complex, the Tarlac Formation north, east and southeast of Pinatubo consists of marine, nonmarine and volcanoclastic sediments formed in the late Miocene and Pliocene. He recognized two life histories of the mountain, which he classified as ancestral and modern Pinatubo, activity of Ancestral Pinatubo seems to have begun about 1.1 million years ago and probably ended tens of thousands of years or more before the birth of Modern Pinatubo. Much of the land around the present volcano consists of remnants of ancestral Pinatubo
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North America
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North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere. It can also be considered a subcontinent of the Americas. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, and to the southeast by South America and the Caribbean Sea. North America covers an area of about 24,709,000 square kilometers, about 16. 5% of the land area. North America is the third largest continent by area, following Asia and Africa, and the fourth by population after Asia, Africa, and Europe. In 2013, its population was estimated at nearly 565 million people in 23 independent states, or about 7. 5% of the worlds population, North America was reached by its first human populations during the last glacial period, via crossing the Bering land bridge. The so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago, the Classic stage spans roughly the 6th to 13th centuries. The Pre-Columbian era ended with the migrations and the arrival of European settlers during the Age of Discovery. Present-day cultural and ethnic patterns reflect different kind of interactions between European colonists, indigenous peoples, African slaves and their descendants, European influences are strongest in the northern parts of the continent while indigenous and African influences are relatively stronger in the south. Because of the history of colonialism, most North Americans speak English, Spanish or French, the Americas are usually accepted as having been named after the Italian explorer Amerigo Vespucci by the German cartographers Martin Waldseemüller and Matthias Ringmann. Vespucci, who explored South America between 1497 and 1502, was the first European to suggest that the Americas were not the East Indies, but a different landmass previously unknown by Europeans. In 1507, Waldseemüller produced a map, in which he placed the word America on the continent of South America. He explained the rationale for the name in the accompanying book Cosmographiae Introductio, for Waldseemüller, no one should object to the naming of the land after its discoverer. He used the Latinized version of Vespuccis name, but in its feminine form America, following the examples of Europa, Asia and Africa. Later, other mapmakers extended the name America to the continent, In 1538. Some argue that the convention is to use the surname for naming discoveries except in the case of royalty, a minutely explored belief that has been advanced is that America was named for a Spanish sailor bearing the ancient Visigothic name of Amairick. Another is that the name is rooted in a Native American language, the term North America maintains various definitions in accordance with location and context. In Canadian English, North America may be used to refer to the United States, alternatively, usage sometimes includes Greenland and Mexico, as well as offshore islands
40.
Mount St. Helens
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Mount St. Helens or Louwala-Clough is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is 96 miles south of Seattle, Washington, and 50 miles northeast of Portland, Mount St. Helens takes its English name from the British diplomat Lord St Helens, a friend of explorer George Vancouver who made a survey of the area in the late 18th century. The volcano is located in the Cascade Range and is part of the Cascade Volcanic Arc and this volcano is well known for its ash explosions and pyroclastic flows. Mount St. Helens is most notorious for its major 1980 eruption, fifty-seven people were killed,250 homes,47 bridges,15 miles of railways, and 185 miles of highway were destroyed. The debris avalanche was up to 0.7 cubic miles in volume, the Mount St. Helens National Volcanic Monument was created to preserve the volcano and allow for its aftermath to be scientifically studied. As with most other volcanoes in the Cascade Range, Mount St. Helens is a large eruptive cone consisting of lava rock interlayered with ash, pumice, the mountain includes layers of basalt and andesite through which several domes of dacite lava have erupted. The largest of the domes formed the previous summit. Both were destroyed in the 1980 eruption, Mount St. Helens is 34 miles west of Mount Adams, in the western part of the Cascade Range. These sister and brother volcanic mountains are approximately 50 miles from Mount Rainier, Mount Hood, the nearest major volcanic peak in Oregon, is 60 miles southeast of Mount St. Helens. Mount St. Helens is geologically young compared with the other major Cascade volcanoes and it formed only within the past 40,000 years, and the pre-1980 summit cone began rising about 2,200 years ago. The volcano is considered the most active in the Cascades within the Holocene epoch, prior to the 1980 eruption, Mount St. Helens was the fifth-highest peak in Washington. It stood out prominently from surrounding hills because of the symmetry and extensive snow and ice cover of the summit cone. The peak rose more than 5,000 feet above its base, the mountain is 6 miles across at its base, which is at an elevation of 4,400 feet on the northeastern side and 4,000 feet elsewhere. At the pre-eruption tree line, the width of the cone was 4 miles. Streams that originate on the volcano enter three main systems, the Toutle River on the north and northwest, the Kalama River on the west. The streams are fed by abundant rain and snow, the average annual rainfall is 140 inches, and the snow pack on the mountains upper slopes can reach 16 feet. The Lewis River is impounded by three dams for power generation. The southern and eastern sides of the drain into an upstream impoundment, the Swift Reservoir
Crater Lake, Oregon, formed around 5,680 BC
Aniakchak-caldera, Alaska
Coatepeque Caldera, El Salvador crater lake
Mount Pinatubo, Philippines
Satellite photo of Lake Taupo
