1.
Etruscan architecture
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Etruscan architecture was created between about 700 BC and 200 BC, when the expanding civilization of ancient Rome finally absorbed Etruscan civilization. The Etruscans were considerable builders in stone, wood and other materials of temples, houses, tombs and city walls, as well as bridges, from about 630 BC, Etruscan architecture was heavily influenced by Greek architecture, which was itself developing through the same period. In turn it influenced Roman architecture, which in its early centuries can be considered as just a variation of Etruscan architecture. But increasingly, from about 200 BC, the Romans looked directly to Greece for their styling, apart from the podia of temples and some house foundations, only the walls and rock-cut tombs were mainly in stone, and have therefore often largely survived. Usually, only the podium or base platform used stone, with the parts of wood and mud-brick. However, there is evidence for the portico columns sometimes using stone and this has left much about Etruscan temples uncertain. The only written account of significance on their architecture is by Vitruvius, many aspects of his description fit what archaeologists can demonstrate, but others do not. It is in any case clear that Etruscan temples could take a number of forms, nonetheless Vitruvius remains the inevitable starting point for a description, and a contrast of Etruscan temples with their Greek and Roman equivalents. There are also a few temples in pottery, and depictions on tombs or vases. Vitruvius specifies three doors and three cellae, one for each of the main Etruscan deities, but archaeological remains do not suggest this was normal, though it is found. Roman sources were in the habit of ascribing to the Etruscans a taste for triads in things such as city planning, the orientation of the temple is not consistent, and may have been determined by a priest watching the flight of birds at the time of foundation. The exteriors of both Greek and Roman temples were highly decorated and colourful, especially in the entablature and roofs. When wood was used for columns, the bases and capitals were often encased in painted terracotta, the Apollo of Veii was part of an acroterion group. The groups from Luni and Talamone are among the most impressive, the podia are also usually higher, and can only be entered at a section of the front, just presenting a blank platform wall elsewhere. There may only be columns at the front portico, in Etruscan temples, more than Roman ones, the portico is deep, often representing, as Vitruvius recommends, half of the area under the roof, with multiple rows of columns. Fluted Tuscan/Doric columns can also be found, against Greek and later Roman conventions, Etruscan architecture shared with Ancient Egyptian architecture the use of large cavetto mouldings as a cornice, though not on the same massive scale. The cavetto took the place of the Greek cymatium in many temples, often painted with vertical tongue patterns and its first version was traditionally dedicated in 509 BC, but in 83 BC it was destroyed by fire, and the rebuilt Greek-style temple completed in 69 BC. But for the building they were summoned from Greece
2.
Cerveteri
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Cerveteri is a town and comune of northern Lazio in the region of the Metropolitan City of Rome. It is famous for the site of the ancient Etruscan city which was one of the most important Etruscan cities with a more than 15 times larger than todays town. Caere was one of the city-states of the Etruscan League and at its height, around 600 BC, the ancient city was situated about 7 km from the sea, a location which made it a wealthy trading town derived originally from the iron ore mines in the Tolfa hills. It had three sea ports including Pyrgi, connected to Caere by a road approximately 13 km long and 10 metres wide, little is known of the ancient city although six temples are known from various sources. Two of them have been excavated, one of Hera, the other in the north of the city, parts of the city walls are still visible today and excavations opened up a theatre. One famous and important work of art is the Sarcophagus of the Spouses, the most famous attraction of Cerveteri is the Necropoli della Banditaccia, which has been declared by UNESCO a World Heritage Site together with the necropolis in Tarquinia. It covers an area of 400 hectares, of which 10 hectares can be visited and it is the largest ancient necropolis in the Mediterranean area. The name Banditaccia comes from the leasing of areas of land to the Cerveteri population by the local landowners, the tombs date from the 9th century BC to the later Etruscan period. The earliest tombs are in the shape of a pit, in which the ashes of the dead were housed, the visitable area contains two such roads, the Via dei Monti Ceriti and the Via dei Monti della Tolfa. Modern knowledge of Etruscan daily life is dependent on the numerous decorative details. The most recent tombs date from the 3rd century BC, some of them are marked by external cippi, which are cylindrical for men, and in the shape of a small house for women. A large number of finds excavated at Cerveteri are in the National Etruscan Museum, Rome, with others in the Vatican Museums, others, mainly pottery, are in the Archaeological Museum at Cerveteri itself. The Rocca Church of Santa Maria Maggiore, including a medieval section reachable from the 1950s addition through a triumphal arch, palazzo Ruspoli, rebuilt as baronal palace by the Orsini in 1533. The portico and the loggia on the façade are from the 17th century and it is connected to Santa Maria Maggiore through a passetto, built in 1760. The small church of SantAntonio Abate, with a 1472 fresco by Lorenzo da Viterbo, the medieval burgh of Ceri Castle of Cerenova Around the city of Cerveteri is an Italian DOC wine region that produces red and white blended wines. The red wines are blends of 60% Sangiovese and Montepulciano, 25% Cesanese and up to 30% of Canaiolo, Carignan, the grapes are limited to a harvest yield of 15 tonnes/ha and the final wine must have a minimum alcohol level of 11%. The white wines are composed of a blend of 50% Trebbiano Romagnolo and Giallo, a maximum of 35% Malvasia di Candia. The grapes are limited to a harvest yield of 14 tonnes/ha, for the ancient bishopric that originally had its seat in Cerveteri and is now a titular see, see Caere
3.
Bandelier National Monument
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Bandelier National Monument is a 33, 677-acre United States National Monument near Los Alamos in Sandoval and Los Alamos Counties, New Mexico. The monument preserves the homes and territory of the Ancestral Puebloans of an era in the Southwest. Most of the structures date to two eras, dating between 1150 and 1600 AD. The Monument is 50 square miles of the Pajarito Plateau, on the slopes of the Jemez Volcanic field in the Jemez Mountains, there are three miles of road, and more than 70 miles of hiking trails. The Monument protects Ancestral Pueblo archeological sites, a diverse and scenic landscape, the park infrastructure was developed in the 1930s by crews of the Civilian Conservation Corps, and are a National Historic Landmark for their well-preserved architecture. The National Park Service co-operates with surrounding pueblos, other federal agencies, the monument received 193,914 visitors in 2011. In October 1976, roughly seventy percent of the monument,23,267 acres, was included within the National Wilderness Preservation System, the parks elevations range from about 5,000 feet at the Rio Grande to over 10,200 feet at the summit of Cerro Grande. The Valles Caldera National Preserve adjoins the monument on the north and west, much of the area was covered with volcanic ash from an eruption of the Valles Caldera volcano 1.14 million years ago. The tuff overlays shales and sandstones deposited during the Permian Period, the volcanic outflow varied in hardness, the Ancestral Pueblo People broke up the firmer materials to use as bricks, while they carved out dwellings from the softer material. Human presence in the area has been dated to over 10,000 years before present, permanent settlements by ancestors of the Puebloan peoples have been dated to 1150 CE, these settlers had moved closer to the Rio Grande by 1550. Spanish colonial settlers arrived in the 18th century, the Pueblo Jose Montoya brought Adolph Bandelier to visit the area in 1880. Looking over the dwellings, Bandelier said, It is the grandest thing I ever saw. Based on documentation and research by Bandelier, there was support for preserving the area, supporting infrastructure, including a lodge, was built during the 1920s and 1930s. This group of 31 buildings illustrates the principles of National Park Service Rustic architecture, being based on local materials. It has been designated as a National Landmark District, Frijoles Canyon contains a number of ancestral pueblo homes, kivas, rock paintings, and petroglyphs. Some of the dwellings were rock structures built on the floor, others were cavates produced by voids in the volcanic tuff of the canyon wall. A1. 2-mile, predominantly paved, Main Loop Trail from the visitor center affords access to these features. A trail extending beyond this leads to Alcove House, a shelter cave produced by erosion of the soft rock and containing a small
4.
New Mexico
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New Mexico is a state located in the southwestern region of the United States of America. It was admitted to the Union as the 47th state on January 6,1912 and it is usually considered one of the Mountain States. New Mexico is fifth by area, the 36th-most populous, inhabited by Native Americans for thousands of years before European exploration, New Mexico was colonized by the Spanish in 1598 Imperial Spanish viceroyalty of New Spain. Later, it was part of independent Mexico before becoming a U. S. territory and eventually a U. S. state as a result of the Mexican–American War. Among U. S. states, New Mexico has the highest percentage of Hispanics, the major Native American nations in the state are Navajo, Pueblo, and Apache peoples. The demography and culture of the state are shaped by these strong Hispanic and Native American influences and its scarlet and gold colors are taken from the royal standards of Spain, along with the ancient sun symbol of the Zia, a Pueblo-related tribe. New Mexico, or Nuevo México in Spanish, is incorrectly believed to have taken its name from the nation of Mexico. The name simply stuck, even though the area had no connection to Mexico or the Mexica Indian tribes, Mexico, formerly a part of New Spain, adopted its name centuries later in 1821, after winning independence from Spanish rule. New Mexico was a part of the independent Mexican Empire and Federal Republic of Mexico for 27 years,1821 through 1848, New Mexico and Mexico developed as neighboring Spanish-speaking communities under Spanish rule, with relatively independent histories. The states total area is 121,412 square miles, the eastern border of New Mexico lies along 103° W longitude with the state of Oklahoma, and 2.2 miles west of 103° W longitude with Texas. On the southern border, Texas makes up the eastern two-thirds, while the Mexican states of Chihuahua and Sonora make up the western third, the western border with Arizona runs along the 109°03 W longitude. The southwestern corner of the state is known as the Bootheel, the 37° N latitude parallel forms the northern boundary with Colorado. The states New Mexico, Colorado, Arizona, and Utah come together at the Four Corners in the corner of New Mexico. New Mexico, although a state, has very little water. Its surface water area is about 250 square miles, the New Mexican landscape ranges from wide, rose-colored deserts to broken mesas to high, snow-capped peaks. Despite New Mexicos arid image, heavily forested mountain wildernesses cover a significant portion of the state, the Sangre de Cristo Mountains, the southernmost part of the Rocky Mountains, run roughly north-south along the east side of the Rio Grande in the rugged, pastoral north. The most important of New Mexicos rivers are the Rio Grande, Pecos, Canadian, San Juan, the Rio Grande is tied for the fourth-longest river in the United States. Tourists visiting these sites bring significant money to the state, other areas of geographical and scenic interest include Kasha-Katuwe Tent Rocks National Monument and the Gila Wilderness in the southwest of the state
5.
Italian language
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By most measures, Italian, together with Sardinian, is the closest to Latin of the Romance languages. Italian is a language in Italy, Switzerland, San Marino, Vatican City. Italian is spoken by minorities in places such as France, Montenegro, Bosnia & Herzegovina, Crimea and Tunisia and by large expatriate communities in the Americas. Many speakers are native bilinguals of both standardized Italian and other regional languages, Italian is the fourth most studied language in the world. Italian is a major European language, being one of the languages of the Organisation for Security and Cooperation in Europe. It is the third most widely spoken first language in the European Union with 65 million native speakers, including Italian speakers in non-EU European countries and on other continents, the total number of speakers is around 85 million. Italian is the working language of the Holy See, serving as the lingua franca in the Roman Catholic hierarchy as well as the official language of the Sovereign Military Order of Malta. Italian is known as the language of music because of its use in musical terminology and its influence is also widespread in the arts and in the luxury goods market. Italian has been reported as the fourth or fifth most frequently taught foreign language in the world, Italian was adopted by the state after the Unification of Italy, having previously been a literary language based on Tuscan as spoken mostly by the upper class of Florentine society. Its development was influenced by other Italian languages and to some minor extent. Its vowels are the second-closest to Latin after Sardinian, unlike most other Romance languages, Italian retains Latins contrast between short and long consonants. As in most Romance languages, stress is distinctive, however, Italian as a language used in Italy and some surrounding regions has a longer history. What would come to be thought of as Italian was first formalized in the early 14th century through the works of Tuscan writer Dante Alighieri, written in his native Florentine. Dante is still credited with standardizing the Italian language, and thus the dialect of Florence became the basis for what would become the language of Italy. Italian was also one of the recognised languages in the Austro-Hungarian Empire. Italy has always had a dialect for each city, because the cities. Those dialects now have considerable variety, as Tuscan-derived Italian came to be used throughout Italy, features of local speech were naturally adopted, producing various versions of Regional Italian. Even in the case of Northern Italian languages, however, scholars are not to overstate the effects of outsiders on the natural indigenous developments of the languages
6.
Rock (geology)
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Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a rock, is a combination of the minerals quartz, feldspar. The Earths outer solid layer, the lithosphere, is made of rock, rock has been used by mankind throughout history. The minerals and metals found in rocks have been essential to human civilization, three major groups of rocks are defined, igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is a component of geology. At a granular level, rocks are composed of grains of minerals, the aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which the rock was formed, many rocks contain silica, a compound of silicon and oxygen that forms 74. 3% of the Earths crust. This material forms crystals with other compounds in the rock, the proportion of silica in rocks and minerals is a major factor in determining their name and properties. Rocks are geologically classified according to such as mineral and chemical composition, permeability, the texture of the constituent particles. These physical properties are the end result of the processes that formed the rocks, over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle. These events produce three general classes of rock, igneous, sedimentary, and metamorphic, the three classes of rocks are subdivided into many groups. However, there are no hard and fast boundaries between allied rocks, hence the definitions adopted in establishing rock nomenclature merely correspond to more or less arbitrary selected points in a continuously graduated series. Igneous rock forms through the cooling and solidification of magma or lava and this magma can be derived from partial melts of pre-existing rocks in either a planets mantle or crust. Typically, the melting of rocks is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, igneous rocks are divided into two main categories, plutonic rock and volcanic. Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earths crust, a common example of this type is granite. Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta, the chemical abundance and the rate of cooling of magma typically forms a sequence known as Bowens reaction series. Most major igneous rocks are found along this scale, about 64. 7% of the Earths crust by volume consists of igneous rocks, making it the most plentiful category. Of these, 66% are basalts and gabbros, 16% are granite, only 0. 6% are syenites and 0. 3% peridotites and dunites
7.
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
8.
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
9.
Types of volcanic eruptions
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Several types of volcanic eruptions—during which lava, tephra, and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed, some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series. There are three different types of eruptions, the most well-observed are magmatic eruptions, which involve the decompression of gas within magma that propels it forward. Phreatomagmatic eruptions are another type of eruption, driven by the compression of gas within magma. Within these wide-defining eruptive types are several subtypes, the weakest are Hawaiian and submarine, then Strombolian, followed by Vulcanian and Surtseyan. The stronger eruptive types are Pelean eruptions, followed by Plinian eruptions, subglacial and phreatic eruptions are defined by their eruptive mechanism, and vary in strength. An important measure of strength is Volcanic Explosivity Index, an order of magnitude scale ranging from 0 to 8 that often correlates to eruptive types. Explosive eruptions are characterized by gas-driven explosions that propels magma and tephra, effusive eruptions, meanwhile, are characterized by the outpouring of lava without significant explosive eruption. Volcanic eruptions vary widely in strength, on the one extreme there are effusive Hawaiian eruptions, which are characterized by lava fountains and fluid lava flows, which are typically not very dangerous. On the other extreme, Plinian eruptions are large, violent, volcanoes are not bound to one eruptive style, and frequently display many different types, both passive and explosive, even the span of a single eruptive cycle. Volcanoes do not always erupt vertically from a crater near their peak. Some volcanoes exhibit lateral and fissure eruptions, notably, many Hawaiian eruptions start from rift zones, and some of the strongest Surtseyan eruptions develop along fracture zones. Scientists believed that pulses of magma mixed together in the chamber before climbing upward—a process estimated to several thousands of years. But Columbia University volcanologists found that the eruption of Costa Rica’s Irazú Volcano in 1963 was likely triggered by magma that took a route from the mantle over just a few months. The volcanic explosivity index is a scale, from 0 to 8 and it is used by the Smithsonian Institutions Global Volcanism Program in assessing the impact of historic and prehistoric lava flows. It operates in a way similar to the Richter scale for earthquakes, the vast majority of volcanic eruptions are of VEIs between 0 and 2. Volcanic eruptions by VEI index Magmatic eruptions produce juvenile clasts during explosive decompression from gas release, Hawaiian eruptions are a type of volcanic eruption, named after the Hawaiian volcanoes with which this eruptive type is hallmark. Hawaiian eruptions are the calmest types of events, characterized by the effusive eruption of very fluid basalt-type lavas with low gaseous content
10.
Consolidation (soil)
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Consolidation is a process by which soils decrease in volume. According to Karl von Terzaghi consolidation is any process which involves a decrease in water content of saturated soil without replacement of water by air, in general it is the process in which reduction in volume takes place by expulsion of water under long term static loads. It occurs when stress is applied to a soil causes the soil particles to pack together more tightly. When this occurs in a soil that is saturated with water, water will be squeezed out of the soil, the magnitude of consolidation can be predicted by many different methods. In the Classical Method, developed by Terzaghi, soils are tested with an oedometer test to determine their compression index and this can be used to predict the amount of consolidation. When stress is removed from a soil, the soil will rebound. If the stress is reapplied, the soil will consolidate again along a recompression curve, the soil which had its load removed is considered to be overconsolidated. This is the case for soils which have previously had glaciers on them, the highest stress that it has been subjected to is termed the preconsolidation stress. The over consolidation ratio or OCR is defined as the highest stress experienced divided by the current stress, a soil which is currently experiencing its highest stress is said to be normally consolidated and to have an OCR of one. A soil could be considered underconsolidated immediately after a new load is applied, the process of consolidation is often explained with an idealized system composed of a spring, a container with a hole in its cover, and water. In this system, the spring represents the compressibility or the structure of the soil itself, the container is completely filled with water, and the hole is closed. A load is applied onto the cover, while the hole is still unopened, at this stage, only the water resists the applied load. As soon as the hole is opened, water starts to drain out through the hole, after some time, the drainage of water no longer occurs. Now, the spring alone resists the applied load and this method assumes consolidation occurs in only one-dimension. Laboratory data is used to construct a plot of strain or void ratio versus effective stress where the stress axis is on a logarithmic scale. The plots slope is the index or recompression index. The equation for consolidation settlement of a consolidated soil can then be determined to be. E0 is the void ratio
11.
Tufa
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Tufa is a variety of limestone formed when carbonate minerals precipitate out of ambient temperature water. Geothermally heated hot springs sometimes produce similar carbonate deposits known as travertine, Tufa is sometimes referred to as travertine. It should not be confused with hot spring travertine, however, Mono Lakes tufa is thermogene, according to Pentecost. Tufa, which is calcareous, should not be confused with tuff, modern and fossil tufa deposits abound with wetland plants, as such many tufa deposits are characterised by their large macrobiological component and are highly porous. Tufa forms either in fluvial channels or in lacustrine settings, ford and Pedley provide a review of tufa systems worldwide. Deposits can be classified by their depositional environment, Pedley provides an extensive classification system, which includes the following classes of fluvial tufa, Spring – Deposits form on emergence from a spring/seep. Barrages often contain a significant detrital component, composed of organic material, lacustrine tufas are generally formed at the periphery of lakes and build up phytoherms and stromatolites. Oncoids are also common in these environments, while fluvial and lacustrine systems make up the bulk of tufa systems worldwide, there are several other important tufa environments. Although sometimes regarded as a distinct carbonate deposit, calcareous sinter formed from ambient temperature water can be considered a sub-type of tufa, calcareous speleothems may be regarded as a form of calcareous sinter. They lack any significant macrophyte component due to the absence of light, Tufa columns are an unusual form of tufa typically associated with saline lakes. They are distinct from most tufa deposits in that lack any significant macrophyte component. Some tufa columns may form from hot-springs and therefore actually be a form of travertine. It is generally thought that such features form from CaCO3 precipitated when carbonate rich source waters emerge into alkaline soda lakes and they have also been found in marine settings. Tufa deposits form an important habitat for a diverse flora, bryophytes and diatoms are well represented. The porosity of the deposits creates a wet habitat ideal for these plants, modern tufa is formed from alkaline waters, supersaturated with calcite. On emergence, waters degas CO2 due to the lower atmospheric pCO2, since carbonate solubility decreases with increased pH, precipitation is induced. Supersaturation may be enhanced by leading to a reduction in pCO2, for example increased air-water interactions at waterfalls may be important. Recently it has demonstrated that microbially induced precipitation may be more important than physico-chemical precipitation
12.
Easter Island
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Easter Island is a Chilean island in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian Triangle. Easter Island is famous for its 887 extant monumental statues, called moai, in 1995, UNESCO named Easter Island a World Heritage Site, with much of the island protected within Rapa Nui National Park. However, human activity, the introduction of the Polynesian rat, by the time of European arrival in 1722, the islands population had dropped to 2, 000–3,000 from an estimated high of approximately 15,000 just a century earlier. European diseases and Peruvian slave raiding in the 1860s further reduced the Rapa Nui population, Easter Island is one of the most remote inhabited islands in the world. Easter Island is a territory of Chile that was annexed in 1888. Administratively, it belongs to the Valparaíso Region, and, more specifically, according to the 2012 Chilean census, the island has about 5,800 residents, of whom some 60 percent are descendants of the aboriginal Rapa Nui. Easter Island is considered part of Insular Chile, the islands official Spanish name, Isla de Pascua, also means Easter Island. However, Norwegian ethnographer Thor Heyerdahl argued that Rapa was the name of Easter Island. William Churchill inquired about the phrase and was told there were three te pito o te henua, these being the three capes of the island. The phrase appears to have used in the same sense as the designation of Lands End at the tip of Cornwall. He was unable to elicit a Polynesian name for the island itself, according to Barthel, oral tradition has it that the island was first named Te pito o te kainga a Hau Maka The little piece of land of Hau Maka. However, there are two words pronounced pito in Rapa Nui, one meaning end and one navel, and the phrase can also mean the Navel of the World. This was apparently its actual meaning, French ethnologist Alphonse Pinart gave it the actual translation the Navel of the World, another name, Mata ki te rangi, means Eyes looking to the sky. Islanders are referred to in Spanish as pascuense, however it is common to refer to members of the community as Rapa Nui. Estimated dates of initial settlement of Easter Island have ranged from 300 to 1200, rectifications in radiocarbon dating have changed almost all of the previously posited early settlement dates in Polynesia. Rapa Nui is now considered to have settled in the narrower range of 700 to 1100 CE. Significant ecological impacts and major cultural investments in monumental architecture and statuary thus began soon after initial settlement, according to oral tradition, the first settlement was at Anakena. The island was most likely populated by Polynesians who navigated in canoes or catamarans from the Gambier Islands or the Marquesas Islands,3,200 km away
13.
Moai
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Moai /ˈmoʊ. aɪ/, or mo‘ai, are monolithic human figures carved by the Rapa Nui people on Easter Island in eastern Polynesia between 1250 and 1500 A. D. Nearly half are still at Rano Raraku, the main moai quarry, almost all moai have overly large heads three-eighths the size of the whole statue. The moai are chiefly the living faces of deified ancestors, the statues still gazed inland across their clan lands when Europeans first visited the island in 1722, but all of them had fallen by the latter part of the 19th century. The production and transportation of the more than 900 statues are considered remarkable creative, the moai toppled after European contact when islander traditions radically changed. The moai are monolithic statues, their minimalist style related to forms found throughout Polynesia, Moai are carved in relatively flat planes, the faces bearing proud but enigmatic expressions. The human figures would be outlined in the wall first. The over-large heads have heavy brows and elongated noses with a distinctive fish-hook-shaped curl of the nostrils, the lips protrude in a thin pout. Like the nose, the ears are elongated and oblong in form, the jaw lines stand out against the truncated neck. The torsos are heavy, and, sometimes, the clavicles are subtly outlined in stone, generally, the anatomical features of the backs are not detailed, but sometimes bear a ring and girdle motif on the buttocks and lower back. Except for one kneeling moai, the statues do not have clearly visible legs, though moai are whole-body statues, they are erroneously referred to as Easter Island heads in some popular literature. Some of the heads at Rano Raraku have been excavated and their bodies seen, the average height of the moai is about 4 m, with the average width at the base around 1.6 m. These massive creations usually weigh in at around 12.5 tonnes each, all but 53 of the more than 900 moai known to date were carved from tuff from Rano Raraku, where 394 moai and incomplete moai are still visible today. There are also 13 moai carved from basalt,22 from trachyte and 17 from fragile red scoria, at the end of carving, the builders would rub the statue with pumice. Easter Island statues are known for their large, broad noses and strong chins, along with rectangle-shaped ears and their bodies are normally squatting, with their arms resting in different positions and are without legs. The major of the ahu are found along the coast and face inland towards the community, there are some inland ahu such as Ahu Akivi. These moai face the community but given the size of the island. The discovery was made by collecting and reassembling broken fragments of coral that were found at the various sites. Subsequently, previously uncategorized finds in the Easter Island museum were re-examined and recategorized as eye fragments, many archaeologists suggest that statues were thus symbols of authority and power, both religious and political
14.
Volcanic gas
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Volcanic gases include a variety of substances given off by active volcanoes. The sources of gases on Earth include, primordial and recycled constituents from the Earths mantle, assimilated constituents from the Earths crust, groundwater. Substances that may become gaseous or give off gases when heated are termed volatile substances. The principal components of volcanic gases are water vapor, carbon dioxide, sulfur either as sulfur dioxide or hydrogen sulfide, nitrogen, argon, helium, neon, methane, carbon monoxide and hydrogen. Other compounds detected in volcanic gases are oxygen, hydrogen chloride, hydrogen fluoride, hydrogen bromide, nitrogen oxide, sulfur hexafluoride, carbonyl sulfide, exotic trace compounds include mercury, halocarbons, and halogen oxide radicals. The abundance of gases varies considerably from volcano to volcano, water vapor is consistently the most common volcanic gas, normally comprising more than 60% of total emissions. Carbon dioxide typically accounts for 10 to 40% of emissions, volcanoes located at convergent plate boundaries emit more water vapor and chlorine than volcanoes at hot spots or divergent plate boundaries. This is caused by the addition of seawater into magmas formed at subduction zones, convergent plate boundary volcanoes also have higher H2O/H2, H2O/CO2, CO2/He and N2/He ratios than hot spot or divergent plate boundary volcanoes. Magma contains dissolved volatile components, as described above, the solubilities of the different volatile constituents are dependent on pressure, temperature and the composition of the magma. As magma ascends towards the surface, the ambient pressure decreases, once the solubility decreases below the volatile concentration, the volatiles will tend to come out of solution within the magma and form a separate gas phase. The gas will initially be distributed throughout the magma as small bubbles, as the magma ascends the bubbles grow through a combination of expansion through decompression and growth as the solubility of volatiles in the magma decreases further causing more gas to exsolve. In the former case, the bubbles may rise through the magma and accumulate at a vertical surface, in volcanoes with an open path to the surface, e. g. Stromboli in Italy, the bubbles may reach the surface and as they pop small explosions occur. In the latter case, the gas can flow rapidly through the continuous permeable network towards the surface and this mechanism has been used to explain activity at Santiaguito, Santa Maria volcano, Guatemala and Soufrière Hills Volcano, Montserrat. If the gas cannot escape fast enough from the magma, it will fragment the magma into small particles of ash, the fluidised ash has a much lower resistance to motion than the viscous magma, so accelerates, causing further expansion of the gases and acceleration of the mixture. This sequence of events drives explosive volcanism, whether gas can escape gently or not is determined by the total volatile contents of the initial magma and the viscosity of the magma, which is controlled by its composition. The term closed system degassing refers to the case where gas and its parent magma ascend together, the composition of the emitted gas is in equilibrium with the composition of the magma at the pressure, temperature where the gas leaves the system. In open system degassing, the gas leaves its parent magma, the gas released at the surface has a composition that is a mass-flow average of the magma exsolved at various depths and is not representative of the magma conditions at any one depth. Molten rock near the atmosphere releases high-temperature volcanic gas, in explosive volcanic eruptions, sudden release of gases from magma may cause rapid movements of the molten rock
15.
Steam
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Steam is water in the gas phase, which is formed when water boils. Steam is invisible, however, steam often refers to wet steam, at lower pressures, such as in the upper atmosphere or at the top of high mountains, water boils at a lower temperature than the nominal 100 °C at standard pressure. If heated further it becomes superheated steam, piston type steam engines played a central role to the Industrial Revolution and modern steam turbines are used to generate more than 80% of the worlds electricity. If liquid water comes in contact with a hot surface or depressurizes quickly below its vapor pressure. Steam explosions have been responsible for many accidents, and may also have been responsible for much of the damage to the plant in the Chernobyl disaster. Steam is traditionally created by heating a boiler via burning coal and other fuels, water vapor that includes water droplets is described as wet steam. As wet steam is heated further, the droplets evaporate, and at a high temperature all of the water evaporates. Superheated steam is steam at a higher than its boiling point for the pressure. Steam tables contain thermodynamic data for water/steam and are used by engineers and scientists in design. Additionally, thermodynamic phase diagrams for water/steam, such as a diagram or a Mollier diagram shown in this article. Steam charts are used for analysing thermodynamic cycles. In agriculture, steam is used for sterilization to avoid the use of harmful chemical agents. Steams capacity to transfer heat is used in the home, for cooking vegetables, steam cleaning of fabric, carpets and flooring. In each case, water is heated in a boiler, steam is also used in ironing clothes to add enough humidity with the heat to take wrinkles out and put intentional creases into the clothing. About 90% of all electricity is generated using steam as the working fluid, in electric generation, steam is typically condensed at the end of its expansion cycle, and returned to the boiler for re-use. However, in cogeneration, steam is piped into buildings through a heating system to provide heat energy after its use in the electric generation cycle. The worlds biggest steam generation system is the New York City steam system, in other industrial applications steam is used for energy storage, which is introduced and extracted by heat transfer, usually through pipes. Steam is a reservoir for thermal energy because of waters high heat of vaporization
16.
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
17.
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
18.
Tephra
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Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts, once clasts have fallen to the ground they remain as tephra unless hot enough to fuse together into pyroclastic rock or tuff. Tephra mixed in with precipitation can also be acidic and cause acid rain, the use of tephra layers, which bear their own unique chemistry and character, as temporal marker horizons in archaeological and geological sites is known as tephrochronology. The word tephra and pyroclast both derive from Greek, τέφρα tephra means ash, while the word pyroclast is derived from the Greek πῦρ, meaning fire, media related to Tephra at Wikimedia Commons How Volcanoes Work Volcanic Materials Identification
19.
Extrusion
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Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed through a die of the desired cross-section and it also forms parts with an excellent surface finish. Drawing is a process, which uses the tensile strength of the material to pull it through the die. This limits the amount of change which can be performed in one step, so it is limited to simpler shapes, Drawing is the main way to produce wire. Metal bars and tubes are often drawn. Extrusion may be continuous or semi-continuous, the extrusion process can be done with the material hot or cold. Commonly extruded materials include metals, polymers, ceramics, concrete, play dough, the products of extrusion are generally called extrudates. Hollow cavities within extruded material cannot be produced using a simple flat extrusion die, instead, the die assumes the shape of a block with depth, beginning first with a shape profile that supports the center section. The die shape then internally changes along its length into the final shape, the material flows around the supports and fuses together to create the desired closed shape. The extrusion process in metals may increase the strength of the material. In 1797, Joseph Bramah patented the first extrusion process for making out of soft metals. It involved preheating the metal and then forcing it through a die via a hand-driven plunger, in 1820 Thomas Burr implemented that process for lead pipe, with a hydraulic press. At that time the process was called squirting, in 1894, Alexander Dick expanded the extrusion process to copper and brass alloys. The process begins by heating the stock material and it is then loaded into the container in the press. A dummy block is placed behind it where the ram then presses on the material to push it out of the die, afterward the extrusion is stretched in order to straighten it. If better properties are required then it may be treated or cold worked. The extrusion ratio is defined as the starting cross-sectional area divided by the area of the final extrusion. One of the advantages of the extrusion process is that this ratio can be very large while still producing quality parts
20.
Sand
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Sand is a naturally occurring granular material composed of finely divided rock and mineral particles. It is defined by size, being finer than gravel and coarser than silt, Sand can also refer to a textural class of soil or soil type, i. e. a soil containing more than 85% sand-sized particles by mass. The second most common type of sand is calcium carbonate, for example aragonite, for example, it is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years like the Caribbean. Sand is a non renewable resource over human timescales, and sand suitable for making concrete is in high demand, in terms of particle size as used by geologists, sand particles range in diameter from 0.0625 mm to 2 mm. An individual particle in this size is termed a sand grain. Sand grains are between gravel and silt, a 1953 engineering standard published by the American Association of State Highway and Transportation Officials set the minimum sand size at 0.074 mm. A1938 specification of the United States Department of Agriculture was 0.05 mm. Sand feels gritty when rubbed between the fingers. ISO14688 grades sands as fine, medium and coarse with ranges 0.063 mm to 0.2 mm to 0.63 mm to 2.0 mm. In the United States, sand is commonly divided into five sub-categories based on size, very fine sand, fine sand, medium sand, coarse sand, and very coarse sand. These sizes are based on the Krumbein phi scale, where size in Φ = -log2D, on this scale, for sand the value of Φ varies from −1 to +4, with the divisions between sub-categories at whole numbers. The composition of sand is highly variable, depending on the local rock sources. The gypsum sand dunes of the White Sands National Monument in New Mexico are famous for their bright, arkose is a sand or sandstone with considerable feldspar content, derived from weathering and erosion of a granitic rock outcrop. Some sands contain magnetite, chlorite, glauconite or gypsum, Sands rich in magnetite are dark to black in color, as are sands derived from volcanic basalts and obsidian. Chlorite-glauconite bearing sands are typically green in color, as are sands derived from basaltic with a high olivine content, many sands, especially those found extensively in Southern Europe, have iron impurities within the quartz crystals of the sand, giving a deep yellow color. Sand deposits in some areas contain garnets and other resistant minerals, the study of individual grains can reveal much historical information as to the origin and kind of transport of the grain. Quartz sand that is weathered from granite or gneiss quartz crystals will be angular. It is called grus in geology or sharp sand in the trade where it is preferred for concrete. Sand that is transported long distances by water or wind will be rounded, people who collect sand as a hobby are known as arenophiles
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Slag
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Slag is the glass-like by-product left over after a desired metal has been separated from its raw ore. Slag is usually a mixture of oxides and silicon dioxide. However, slags can contain metal sulfides and elemental metals, in nature, iron, copper, lead, nickel and other metals are found in impure states called ores, often oxidized and mixed in with silicates of other metals. During smelting, when the ore is exposed to high temperatures, Slag is the collection of compounds that are removed. In many smelting processes, oxides are introduced to control the slag chemistry, assisting in the removal of impurities, in this case, the slag is termed synthetic. Ferrous and non-ferrous smelting processes produce different slags, the smelting of copper and lead in non-ferrous smelting, for instance, is designed to remove the iron and silica that often occurs with those ores, and separates them as iron-silicate-based slags. Slag from steel mills in ferrous smelting, on the hand, is designed to minimize iron loss and so mainly contains oxides of calcium, silicon, magnesium. Any sandy component or quartz component of the original ore automatically carries through the process as silicon dioxide. As the slag is channeled out of the furnace, water is poured over it and this rapid cooling, often from a temperature of around 2,600 °F, is the start of the granulating process. This process causes several chemical reactions to take place within the slag, the water carries the slag in its slurry format to a large agitation tank, from where it is pumped along a piping system into a number of gravel based filter beds. The filter beds then retain the slag granules, while the drains away and is returned to the system. During the Bronze Age of the Mediterranean there were a vast number of metallurgical processes in use. A slag by-product of such workings was a colorful, glassy and it was primarily blue or green and was formerly chipped away and melted down to make glassware products and jewelry. It was also ground into powder to add to glazes for use in ceramics, some of the earliest such uses for the by-products of slag have been found in ancient Egypt. Historically, the re-smelting of iron ore slag was common practice, during the early 20th century, iron ore slag was also ground to a powder and used to make agate glass, also known as slag glass. Ground granulated slag is used in concrete in combination with Portland cement as part of a blended cement. Ground granulated slag reacts with water to produce cementitious properties, concrete containing ground granulated slag develops strength over a longer period, leading to reduced permeability and better durability. Since the unit volume of Portland cement is reduced, this concrete is less vulnerable to alkali-silica, the slag can also be used to create fibers used as an insulation material called slag wool
This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Tuff". Encyclopædia Britannica (11th ed.). Cambridge University Press.
