Jeju Island is an island in Jeju Province, South Korea. The island lies in the Korea Strait, south of South Jeolla Province; the island contains Lava Tubes. Jejudo has a moderate climate. Jeju is a popular holiday destination and a sizable portion of the economy relies on tourism and economic activity from its civil/naval base; the island has been called by many different names including: Doi Dongyeongju Juho Tammora Seomra Tangna Tamna Quelpart, Quelparte or Quelpaert Island Joonwonhado Taekseungnido Samdado Before the Japanese annexation in 1910, the island was known as Quelpart to Europeans. The name Quelpart came from the first European ship to spot the island, the Dutch Quelpaert, which sighted it after being blown off course on its way to the Dutch trading base in Nagasaki, from Taiwan; the earliest known polity on the island was the kingdom of Tamna. From April 3, 1948 to May 1949, the South Korean government conducted an anticommunist campaign to suppress an attempted uprising on the island.
The main cause for the rebellion was the election scheduled for May 10, 1948, designed by the United Nations Temporary Commission on Korea to create a new government for all of Korea. The elections were only planned for the south of the country, the half of the peninsula under UNTCOK control. Fearing that the elections would further reinforce division, guerrilla fighters for the South Korean Labor party reacted violently, attacking local police and rightist youth groups stationed on Jeju Island. Atrocities were committed by both sides, but those by South Korean government forces are the best-documented. On one occasion, American soldiers discovered the bodies of 97 people, killed by government forces. On another, American soldiers encountered police. Between 40,000 and 60,000 people died as a result of the rebellion, or up to 25% of the island’s total population; some 40,000 others fled to Japan to escape the fighting. In the decades after the uprising, memory of the event was suppressed by the government through strict punishment.
However, in 2006, the Korean government apologized for its role in the killings and promised reparations. As of 2010, these had not been paid. In 2008, bodies of victims of a massacre were discovered in a mass grave near Jeju International Airport. On November 11, 2018, It was announced that preparations were being made for North Korean leader Kim Jung-Un to visit Jeju during his upcoming visit to South Korea. Kim would be transported to Jeju via helicopter; the announcement came in after 200 tonnes of tangerines which were harvested in Jeju were flown to North Korea as a sign of appreciation for nearly 2 tonnes of North Korean mushrooms which Kim allowed South Korean President Moon Jae-In to take back to South Korea following the September 2018 inter-Korean summit. Jejudo is a volcanic island, dominated by Hallasan: a volcano 1,950 metres high and the highest mountain in South Korea; the island measures 73 kilometres across, east to west, 41 kilometres from north to south. The island formed by volcanic eruptions 2 million years ago, during the Cenozoic era.
The island consists chiefly of lava. An area covering about 12% of Jejudo is known as Gotjawal Forest; this area remained uncultivated until the 21st century, as its base of'a'a lava made it difficult to develop for agriculture. Because this forest remained pristine for so long, it has a unique ecology; the forest is the main source of groundwater and thus the main water source for the half million people of the island, because rainwater penetrates directly into the aquifer through the cracks of the'a'a lava under the forest. Gotjawal forest is considered an internationally important wetland under the Ramsar Convention by some researchers because it is the habitat of unique species of plants and is the main source of water for the residents, although to date it has not been declared a Ramsar site. About 2 million years ago, the island of Jeju was formed through volcanic activity. About 1.2 million years ago, a magma chamber began to erupt. About 700 thousand years ago, the island had been formed through volcanic activity.
Volcanic activity stopped for 100 thousand years. About 300 thousand years ago, volcanic activity restarted along the coastline. About 100 thousand years ago, volcanic activity formed Halla Mountain. About 25 thousand years ago, lateral eruptions around Halla Mountain left multiple oreum. Volcanic activity stopped and prolonged weathering and erosion helped shape the island. Jeju has a humid subtropical climate. Four distinct seasons are experienced on Jeju. In January 2016, a cold wave affected the region. Snow and frigid weather forced the cancellation of 1,200 flights on Jejudo, stranding 90,300 passengers. Tourism is an important component of the local economy; the island is sometimes called "South Korea’s Hawaii". Tourists from China do not require a visa to visit Jeju, unlike the rest of South Kor
Korea is a region in East Asia. Since 1948, it has been divided between two distinct sovereign states: South Korea. Korea consists of the Korean Peninsula, Jeju Island, several minor islands near the peninsula. Korea is bordered by China to the northwest, Russia to the northeast, neighbours Japan to the east by the Korea Strait and the Sea of Japan. During the first half of the 1st millennium, Korea was divided between the three competing states of Baekje and Silla, together known as the "Three Kingdoms of Korea". In the second half of the 1st millennium and Goguryeo were conquered by Silla, leading to the "Unified Silla" period. Meanwhile, Balhae formed in the north following the collapse of Goguryeo. Unified Silla collapsed into three separate states due to civil war, ushering in the Later Three Kingdoms. Toward the end of the 1st millennium Goryeo, a revival of Goguryeo, defeated the two other states and unified the Korean Peninsula as one single state. Around the same time, Balhae collapsed and its last crown prince fled south to Goryeo.
Goryeo, whose name developed into the modern exonym "Korea", was a cultured state that created the world's first metal movable type in 1234. However, multiple invasions by the Mongol Empire during the 13th century weakened the nation, which agreed to become a vassal state after decades of fighting. Following military resistance under King Gongmin which ended Mongol political influence in Goryeo, severe political strife followed, Goryeo fell to a coup led by General Yi Seong-gye, who established Joseon in 1392; the first 200 years of Joseon were marked by relative peace. During this period, the Korean alphabet was created by Sejong the Great in the 15th century and there was increasing influence of Confucianism. During the part of the dynasty, Korea's isolationist policy earned it the Western nickname of the "Hermit Kingdom". By the late 19th century, the country became the object of imperial design by the Empire of Japan. After the First Sino-Japanese War, despite the Korean Empire's effort to modernize, it was annexed by Japan in 1910 and ruled by Imperial Japan until the end of World War II in August 1945.
In 1945, the Soviet Union and the United States agreed on the surrender of Japanese forces in Korea in the aftermath of World War II, leaving Korea partitioned along the 38th parallel. The North was under Soviet occupation and the South under U. S. occupation. These circumstances soon became the basis for the division of Korea by the two superpowers, exacerbated by their inability to agree on the terms of Korean independence; the Communist-inspired government in the North received backing from the Soviet Union in opposition to the pro-Western government in the South, leading to Korea's division into two political entities: North Korea, South Korea. Tensions between the two resulted in the outbreak of the Korean War in 1950. With involvement by foreign troops, the war ended in a stalemate in 1953, but without a formalized peace treaty; this status contributes to the high tensions. Both governments of the two Koreas claim to be the sole legitimate government of the region. "Korea" is the modern spelling of "Corea", a name attested in English as early as 1614.
Korea was transliterated as Cauli in The Travels of Marco Polo, of the Chinese 高麗. This was the Hanja for the Korean kingdom of Goryeo, which ruled most of the Korean peninsula during Marco Polo's time. Korea's introduction to the West resulted from trade and contact with merchants from Arabic lands, with some records dating back as far as the 9th century. Goryeo's name was a continuation of Goguryeo the northernmost of the Three Kingdoms of Korea, known as Goryeo beginning in the 5th century; the original name was a combination of the adjective go with the name of a local Yemaek tribe, whose original name is thought to have been either *Guru or *Gauri. With expanding British and American trade following the opening of Korea in the late 19th century, the spelling "Korea" appeared and grew in popularity; the name Korea is now used in English contexts by both North and South Korea. In South Korea, Korea as a whole is referred to as Hanguk; the name references Samhan, referring to the Three Kingdoms of Korea, not the ancient confederacies in the southern Korean Peninsula.
Although written in Hanja as 韓, 幹, or 刊, this Han has no relation to the Chinese place names or peoples who used those characters but was a phonetic transcription of a native Korean word that seems to have had the meaning "big" or "great" in reference to leaders. It has been tentatively linked with the title khan used by the nomads of Central Asia. In North Korea, China and Japan, Korea as a whole is referred to as. "Great Joseon" was the name of the kingdom ruled by the Joseon dynasty from 1393 until their declaration of the short-lived Great Korean Empire in 1897. King Taejo had named them for the earlier Kojoseon, who ruled northern Korea from its legendary prehistory until their conquest in 108 BC by China's Han Empire; this go is the Hanja 古 and
Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption at temperatures from 700 to 1,200 °C. The structures resulting from subsequent solidification and cooling are sometimes described as lava; the molten rock is formed in the interior of some planets, including Earth, some of their satellites, though such material located below the crust is referred to by other terms. A lava flow is a moving outpouring of lava created during a non-explosive effusive eruption; when it has stopped moving, lava solidifies to form igneous rock. The term lava flow is 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 and shear thinning properties. Explosive eruptions produce a mixture of volcanic ash and other fragments called tephra, rather than lava flows; the word lava comes from Italian, is derived from the Latin word labes which means a fall or slide.
The first use in connection with extruded magma was in a short account written by Francesco Serao on the eruption of Vesuvius in 1737. Serao described "a flow of fiery lava" as an analogy to the flow of water and mud down the flanks of the volcano following heavy rain; the composition of all lava of the Earth's crust is dominated by silicate minerals feldspars, pyroxenes, amphiboles and quartz. Igneous rocks, which form lava flows when erupted, can be classified into three chemical types: felsic and mafic; these classes are chemical, the chemistry of lava tends to correlate with the magma temperature, its viscosity and its mode of eruption. Felsic or silicic lavas such as rhyolite and dacite form lava spines, lava domes or "coulees" and are associated with pyroclastic deposits. Most silicic lava flows are viscous, fragment as they extrude, producing blocky autobreccias; the high viscosity and strength are the result of their chemistry, high in silica, potassium and calcium, forming a polymerized liquid rich in feldspar and quartz, thus has a higher viscosity than other magma types.
Felsic magmas can erupt at temperatures as low as 650 to 750 °C. Unusually hot rhyolite lavas, 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, somewhat richer in magnesium and iron. Intermediate lavas form andesite domes and block lavas, may occur on steep composite volcanoes, such as in the Andes. Poorer in aluminium and silica than felsic lavas, commonly hotter, they tend to be less viscous. Greater temperatures tend to destroy polymerized bonds within the magma, promoting more fluid behaviour and a greater tendency to form phenocrysts. Higher iron and magnesium tends to manifest as a darker groundmass, occasionally amphibole or pyroxene phenocrysts. Mafic or basaltic lavas are typified by their high ferromagnesian content, erupt at temperatures in excess of 950 °C. Basaltic magma is high in iron and magnesium, has lower aluminium and silica, which taken together reduces the degree of polymerization within the melt.
Owing to the higher temperatures, viscosities can be low, although still thousands of times higher than water. The low degree of polymerization and high temperature favors chemical diffusion, so it is common to see large, well-formed phenocrysts within mafic lavas. Basalt lavas tend to produce low-profile shield volcanoes or "flood basalt fields", because the fluidal lava flows for long distances from the vent; the thickness of a basalt lava on a low slope, may be much greater than the thickness of the moving lava flow at any one time, because basalt lavas may "inflate" by supply of lava beneath a solidified crust. Most basalt lavas are of pāhoehoe types, rather than block lavas. Underwater, they can form pillow lavas, which are rather similar to entrail-type pahoehoe lavas on land. Ultramafic lavas such as komatiite and magnesian magmas that form boninite take the composition and temperatures of eruptions to the extreme. Komatiites contain over 18% magnesium oxide, are thought to have erupted at temperatures of 1,600 °C.
At this temperature there is no polymerization of the mineral compounds, creating a mobile liquid. Most if not all ultramafic lavas are no younger than the Proterozoic, with a few ultramafic magmas known from the Phanerozoic. No modern komatiite lavas are known, as the Earth's mantle has cooled too much to produce magnesian magmas; some lavas of unusual composition have erupted onto the surface of the Earth. These include: Carbonatite and natrocarbonatite lavas are known from Ol Doinyo Lengai volcano in Tanzania, the sole example of an active carbonatite volcano. Iron oxide lavas are thought to be the source of the iron ore at Kiruna, Sweden which formed during the Proterozoic. Iron oxide lavas of Pliocene age occur at the El Laco volcanic complex on the Chile-Argentina border. Iron oxide lavas are thought to be the result of immiscible separation of iron oxide magma from a parental magma of calc-alkaline or alkaline composition. Sulfur lava flows up to 250 metres 10 metres wide occur at Lastarria volcano, Chile.
They were formed by the melting of sulfur deposits at temperatures as low as 113 °C
The Azores the Autonomous Region of the Azores, is one of the two autonomous regions of Portugal. It is an archipelago composed of nine volcanic islands in the North Atlantic Ocean about 1,360 km west of continental Portugal, about 1,643 km west of Lisbon, in continental Portugal, about 1,507 km northwest of Morocco, about 1,925 km southeast of Newfoundland, Canada, its main industries are agriculture, dairy farming, livestock and tourism, becoming the major service activity in the region. In addition, the government of the Azores employs a large percentage of the population directly or indirectly in the service and tertiary sectors; the main capital of the Azores is Ponta Delgada. There are an islet cluster, in three main groups; these are Corvo, to the west. They lie in a northwest-southeast direction. All the islands have volcanic origins, although some, such as Santa Maria, have had no recorded activity since the islands were settled. Mount Pico, on the island of Pico, is the highest point in Portugal, at 2,351 m.
If measured from their base at the bottom of the ocean to their peaks, which thrust high above the surface of the Atlantic, the Azores are some of the tallest mountains on the planet. The climate of the Azores is mild for such a northerly location, being influenced by its distance from the continents and by the passing Gulf Stream. Due to the marine influence, temperatures remain mild year-round. Daytime temperatures fluctuate between 16 °C and 25 °C depending on season. Temperatures above 30 °C or below 3 °C are unknown in the major population centres, it is generally wet and cloudy. The culture, dialect and traditions of the Azorean islands vary because these once-uninhabited and remote islands were settled sporadically over a span of two centuries. A small number of alleged hypogea, earthen structures carved into rocks that were used for burials, have been identified on the islands of Corvo, Santa Maria and Terceira by Portuguese archaeologist Nuno Ribeiro, who speculated that they might date back 2000 years, implying a human presence on the island before the Portuguese.
These kinds of structures have been used in the Azores to store cereals and suggestions by Ribeiro that they might be burial sites are unconfirmed. Detailed examination and dating to authenticate the validity of these speculations is lacking, it is unclear whether these structures are natural or man-made and whether they predate the 15th-century Portuguese colonization of the Azores. Therefore, clear confirmation of a pre-Portuguese human presence in the archipelago has not yet been published; the islands were known in the fourteenth century, parts of them appear in the Catalan Atlas. In 1427, a captain sailing for Prince Henry the Navigator Gonçalo Velho, may have rediscovered the Azores, but this is not certain. In Thomas Ashe's 1813 work, A History of the Azores, the author identified a Fleming, Joshua Vander Berg of Bruges, who made landfall in the archipelago during a storm on his way to Lisbon, he stated that the Portuguese claimed it for Portugal. Other stories note the discovery of the first islands by sailors in the service of Henry the Navigator, although there are few documents to support the claims.
Although it is said that the archipelago received its name from the goshawk, a common bird at the time of discovery, it is unlikely that the bird nested or hunted in the islands. There were no large animals on Santa Maria, so after its discovery and before settlement began, sheep were let loose on the island to supply future settlers with food. Settlement did not take place however. There was not much interest among the Portuguese people to live in an isolated archipelago so far from civilization. Gonçalo Velho Cabral patiently gathered resources and settlers for the next three years and sailed to establish colonies first on Santa Maria and on São Miguel. Settlers cleared bush and rocks to plant crops—grain, grape vines, sugar cane, other plants suitable for local use and of commercial value, they brought domesticated animals, such as chickens, cattle, sheep and pigs and built houses and established villages. The archipelago was settled from mainland Portugal. Portuguese settlers came from the provinces of Algarve, Minho and Ribatejo as well as Madeira.
São Miguel was first settled in 1449, the settlers – from the Estremadura, Alto Alentejo and Algarve areas of mainland Portugal, under the command of Gonçalo Velho Cabral – landed at the site of modern-day Povoação. Many early settlers were Portuguese Sephardic Jews who fled the pressures of inquisition in mainland Portugal. In 1522, Vila Franca do Campo the capital of the island, was devastated by an earthquake and landslide that killed about 5,000 people, the capital was moved to Ponta Delgada; the town of Vila Franca do Campo was rebuilt on the original site and today is a thriving fishing and yachting port. Ponta Delgada received its city status in 1546. From the first settlement, the pioneers applied themselves to agriculture and by the 15th century Graciosa exported wheat, barley and brandy; the goods were sent to Terceira because of the proximity of the island. During the 18th and 19th centuries, Gra
A stalagmite is a type of rock formation that rises from the floor of a cave due to the accumulation of material deposited on the floor from ceiling drippings. Stalagmites may be composed of lava, mud, pitch, sand and amberat; the corresponding formation hanging down from the ceiling of a cave is a stalactite. Mnemonics have been developed for; the most common stalagmites are speleothems, which form in limestone caves. Stalagmite formation occurs only under certain pH conditions within the cavern, they form through deposition of calcium carbonate and other minerals, precipitated from mineralized water solutions. Limestone is the chief form of calcium carbonate rock, dissolved by water that contains carbon dioxide, forming a calcium bicarbonate solution in caverns; the partial pressure of carbon dioxide in the water must be greater than the partial pressure of carbon dioxide in the cave chamber for conventional stalagmite growth. If stalactites – the ceiling formations – grow long enough to connect with stalagmites on the floor, they form a column.
Stalagmites should not be touched, since the rock buildup is formed by minerals precipitating out of the water solution onto the existing surface. Oils and dirt from human contact can stain the formation and change its color permanently. Another type of stalagmite is formed in lava tubes; the mechanism of formation is similar to that of limestone stalagmites. It is still the deposition of material on the floors of caves. A key difference with lava stalagmites is that once the lava has ceased flowing, so too will the stalagmites cease to grow; this means. Stalagmites in lava tubes are rarer than their stalactite counterparts because during formation the dripping material falls onto still-moving lava floors that absorb or carry the material away; the generic term "lavacicle" has been applied to lava stalactites and stalagmites indiscriminately, evolved from the word "icicle". A common stalagmite found seasonally or year round in many caves is the ice stalagmite referred to as icicles in above-ground contexts.
Water seepage from the surface will penetrate into a cave and if temperatures are below freezing temperature, the water will collect on the floor into stalagmites. Deposition may occur directly from the freezing of water vapor. Similar to lava stalagmites, ice stalagmites form quickly within hours or days. Unlike lava stalagmites however, they may grow back as long. Ice stalagmites are more common than their stalactite counterparts because warmer air rises to the ceilings of caves and may raise temperatures to above freezing. Ice stalactites may form corresponding stalagmites below them, given time, may grow together to form an ice column. Stalactites and stalagmites can form on concrete ceilings and floors, although they form much more there than in the natural cave environment; the secondary deposits derived from concrete are the result of concrete degradation, where calcium ions are leached out of the concrete in solution and redeposited on the underside of a concrete structure to form stalactites and stalagmites.
Calcium carbonate deposition as a stalagmite occurs when the solution carries the calcium laden leachate solution to the ground under the concrete structure. Carbon dioxide is absorbed into the alkaline leachate solution, which facilitates the chemical reactions to deposit calcium carbonate as a stalagmite; these stalagmites grow taller than a few centimetres. Secondary deposits, which create stalagmites, flowstone etc. outside the natural cave environment, are referred to as “calthemites”. These concrete derived secondary deposits can’t be referred to as “speleothems” due to the definition of the word; the largest known stalagmite in the world exceeds 70 metres in height and is in Sơn Đoòng Cave, Vietnam. In the Zagros Mountains of south Iran 6 km from the ancient city of Bishapur, in the Shapur cave on the fourth of five terraces stands the 3rd-century colossal statue of Shapur I, second ruler of the Sassanid Empire; the statue, carved from one stalagmite, is nearly 7 m high. The Virtual Cave: Stalagmites
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity can be conceptualized as quantifying the frictional force that arises between adjacent layers of fluid that are in relative motion. For instance, when a fluid is forced through a tube, it flows more near the tube's axis than near its walls. In such a case, experiments show; this is because a force is required to overcome the friction between the layers of the fluid which are in relative motion: the strength of this force is proportional to the viscosity. A fluid that has no resistance to shear stress is known as an inviscid fluid. Zero viscosity is observed only at low temperatures in superfluids. Otherwise, the second law of thermodynamics requires all fluids to have positive viscosity. A fluid with a high viscosity, such as pitch, may appear to be a solid; the word "viscosity" is derived from the Latin "viscum", meaning mistletoe and a viscous glue made from mistletoe berries.
In materials science and engineering, one is interested in understanding the forces, or stresses, involved in the deformation of a material. For instance, if the material were a simple spring, the answer would be given by Hooke's law, which says that the force experienced by a spring is proportional to the distance displaced from equilibrium. Stresses which can be attributed to the deformation of a material from some rest state are called elastic stresses. In other materials, stresses are present which can be attributed to the rate of change of the deformation over time; these are called. For instance, in a fluid such as water the stresses which arise from shearing the fluid do not depend on the distance the fluid has been sheared. Viscosity is the material property which relates the viscous stresses in a material to the rate of change of a deformation. Although it applies to general flows, it is easy to visualize and define in a simple shearing flow, such as a planar Couette flow. In the Couette flow, a fluid is trapped between two infinitely large plates, one fixed and one in parallel motion at constant speed u.
If the speed of the top plate is low enough in steady state the fluid particles move parallel to it, their speed varies from 0 at the bottom to u at the top. Each layer of fluid moves faster than the one just below it, friction between them gives rise to a force resisting their relative motion. In particular, the fluid applies on the top plate a force in the direction opposite to its motion, an equal but opposite force on the bottom plate. An external force is therefore required in order to keep the top plate moving at constant speed. In many fluids, the flow velocity is observed to vary linearly from zero at the bottom to u at the top. Moreover, the magnitude F of the force acting on the top plate is found to be proportional to the speed u and the area A of each plate, inversely proportional to their separation y: F = μ A u y; the proportionality factor μ is the viscosity of the fluid, with units of Pa ⋅ s. The ratio u / y is called the rate of shear deformation or shear velocity, is the derivative of the fluid speed in the direction perpendicular to the plates.
If the velocity does not vary linearly with y the appropriate generalization is τ = μ ∂ u ∂ y, where τ = F / A, ∂ u / ∂ y is the local shear velocity. This expression is referred to as Newton's law of viscosity. In shearing flows with planar symmetry, it is what defines μ, it is a special case of the general definition of viscosity, which can be expressed in coordinate-free form. Use of the Greek letter mu for the viscosity is common among mechanical and chemical engineers, as well as physicists. However, the Greek letter eta is used by chemists and the IUPAC; the viscosity μ is sometimes referred to as the shear viscosity. However, at least one author discourages the use of this terminology, noting that μ can appear in nonshearing flows in addition to shearing flows. In general terms, the viscous stresses in a fluid are defined as those resulting from the relative velocity of different fluid particles; as such, the viscous stresses. If the velocity gradients are small to a first approximation the v