The hectare is an SI accepted metric system unit of area equal to a square with 100-metre sides, or 10,000 m2, is used in the measurement of land. There are 100 hectares in one square kilometre. An acre is about 0.405 hectare and one hectare contains about 2.47 acres. In 1795, when the metric system was introduced, the "are" was defined as 100 square metres and the hectare was thus 100 "ares" or 1⁄100 km2; when the metric system was further rationalised in 1960, resulting in the International System of Units, the are was not included as a recognised unit. The hectare, remains as a non-SI unit accepted for use with the SI units, mentioned in Section 4.1 of the SI Brochure as a unit whose use is "expected to continue indefinitely". The name was coined from the Latin ārea; the metric system of measurement was first given a legal basis in 1795 by the French Revolutionary government. The law of 18 Germinal, Year III defined five units of measure: The metre for length The are for area The stère for volume of stacked firewood The litre for volumes of liquid The gram for massIn 1960, when the metric system was updated as the International System of Units, the are did not receive international recognition.
The International Committee for Weights and Measures makes no mention of the are in the current definition of the SI, but classifies the hectare as a "Non-SI unit accepted for use with the International System of Units". In 1972, the European Economic Community passed directive 71/354/EEC, which catalogued the units of measure that might be used within the Community; the units that were catalogued replicated the recommendations of the CGPM, supplemented by a few other units including the are whose use was limited to the measurement of land. The names centiare, deciare and hectare are derived by adding the standard metric prefixes to the original base unit of area, the are; the centiare is one square metre. The deciare is ten square metres; the are is a unit of area, used for measuring land area. It was defined by older forms of the metric system, but is now outside the modern International System of Units, it is still used in colloquial speech to measure real estate, in particular in Indonesia, in various European countries.
In Russian and other languages of the former Soviet Union, the are is called sotka. It is used to describe the size of suburban dacha or allotment garden plots or small city parks where the hectare would be too large; the decare is derived from deca and are, is equal to 10 ares or 1000 square metres. It is used in Norway and in the former Ottoman areas of the Middle East and the Balkans as a measure of land area. Instead of the name "decare", the names of traditional land measures are used, redefined as one decare: Stremma in Greece Dunam, donum, or dönüm in Israel, Jordan, Lebanon and Turkey Mål is sometimes used for decare in Norway, from the old measure of about the same area; the hectare, although not a unit of SI, is the only named unit of area, accepted for use within the SI. In practice the hectare is derived from the SI, being equivalent to a square hectometre, it is used throughout the world for the measurement of large areas of land, it is the legal unit of measure in domains concerned with land ownership and management, including law, agriculture and town planning throughout the European Union.
The United Kingdom, United States, to some extent Canada use the acre instead. Some countries that underwent a general conversion from traditional measurements to metric measurements required a resurvey when units of measure in legal descriptions relating to land were converted to metric units. Others, such as South Africa, published conversion factors which were to be used "when preparing consolidation diagrams by compilation". In many countries, metrication clarified existing measures in terms of metric units; the following legacy units of area have been redefined as being equal to one hectare: Jerib in Iran Djerib in Turkey Gong Qing in Hong Kong / mainland China Manzana in Argentina Bunder in The Netherlands The most used units are in bold. One hectare is equivalent to: 1 square hectometre 15 mǔ or 0.15 qǐng 10 dunam or dönüm 10 stremmata 6.25 rai ≈ 1.008 chō ≈ 2.381 feddan Conversion of units Hecto- Hectometre Order of magnitude Official SI website: Table 6. Non-SI units accepted for use with the International System of Units
Gold is a chemical element with symbol Au and atomic number 79, making it one of the higher atomic number elements that occur naturally. In its purest form, it is a bright reddish yellow, soft and ductile metal. Chemically, gold is a group 11 element, it is solid under standard conditions. Gold occurs in free elemental form, as nuggets or grains, in rocks, in veins, in alluvial deposits, it occurs in a solid solution series with the native element silver and naturally alloyed with copper and palladium. Less it occurs in minerals as gold compounds with tellurium. Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of nitric acid and hydrochloric acid, which forms a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to refine gold and to confirm the presence of gold in metallic objects, giving rise to the term acid test. Gold dissolves in alkaline solutions of cyanide, which are used in mining and electroplating.
Gold dissolves in mercury, forming amalgam alloys. A rare element, gold is a precious metal, used for coinage and other arts throughout recorded history. In the past, a gold standard was implemented as a monetary policy, but gold coins ceased to be minted as a circulating currency in the 1930s, the world gold standard was abandoned for a fiat currency system after 1971. A total of 186,700 tonnes of gold exists above ground, as of 2015; the world consumption of new gold produced is about 50% in jewelry, 40% in investments, 10% in industry. Gold's high malleability, resistance to corrosion and most other chemical reactions, conductivity of electricity have led to its continued use in corrosion resistant electrical connectors in all types of computerized devices. Gold is used in infrared shielding, colored-glass production, gold leafing, tooth restoration. Certain gold salts are still used as anti-inflammatories in medicine; as of 2017, the world's largest gold producer by far was China with 440 tonnes per year.
Gold is the most malleable of all metals. It can be drawn into a monoatomic wire, stretched about twice before it breaks; such nanowires distort via formation and migration of dislocations and crystal twins without noticeable hardening. A single gram of gold can be beaten into a sheet of 1 square meter, an avoirdupois ounce into 300 square feet. Gold leaf can be beaten thin enough to become semi-transparent; the transmitted light appears greenish blue, because gold reflects yellow and red. Such semi-transparent sheets strongly reflect infrared light, making them useful as infrared shields in visors of heat-resistant suits, in sun-visors for spacesuits. Gold is a good conductor of electricity. Gold has a density of 19.3 g/cm3 identical to that of tungsten at 19.25 g/cm3. By comparison, the density of lead is 11.34 g/cm3, that of the densest element, osmium, is 22.588±0.015 g/cm3. Whereas most metals are gray or silvery white, gold is reddish-yellow; this color is determined by the frequency of plasma oscillations among the metal's valence electrons, in the ultraviolet range for most metals but in the visible range for gold due to relativistic effects affecting the orbitals around gold atoms.
Similar effects impart a golden hue to metallic caesium. Common colored gold alloys include the distinctive eighteen-karat rose gold created by the addition of copper. Alloys containing palladium or nickel are important in commercial jewelry as these produce white gold alloys. Fourteen-karat gold-copper alloy is nearly identical in color to certain bronze alloys, both may be used to produce police and other badges. White gold alloys can be made with nickel. Fourteen- and eighteen-karat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. Blue gold can be made by alloying with iron, purple gold can be made by alloying with aluminium. Less addition of manganese, aluminium and other elements can produce more unusual colors of gold for various applications. Colloidal gold, used by electron-microscopists, is red. Gold has only one stable isotope, 197Au, its only occurring isotope, so gold is both a mononuclidic and monoisotopic element. Thirty-six radioisotopes have been synthesized, ranging in atomic mass from 169 to 205.
The most stable of these is 195Au with a half-life of 186.1 days. The least stable is 171Au. Most of gold's radioisotopes with atomic masses below 197 decay by some combination of proton emission, α decay, β+ decay; the exceptions are 195Au, which decays by electron capture, 196Au, which decays most by electron capture with a minor β− decay path. All of gold's radioisotopes with atomic masses above 197 decay by β− decay. At least 32 nuclear isomers have been characterized, ranging in atomic mass from 170 to 200. Within that range, only 178Au, 180Au, 181Au, 182Au, 188Au do not have isomers. Gold's most stable isomer is 198m2Au with a half-life of 2.27 days. Gold's least stable isomer is 177m2Au with a half-life of only 7 ns. 184m1Au has three decay paths: β+ decay, isomeric
A tomb is a repository for the remains of the dead. It is any structurally enclosed interment space or burial chamber, of varying sizes; the word is used in a broad sense to encompass a number of such types of places of interment or burial, including: Architectural shrines – in Christianity, an architectural shrine above a saint's first place of burial, as opposed to a similar shrine on which stands a reliquary or feretory into which the saint's remains have been transferred Burial vault – a stone or brick-lined underground space for multiple burials vaulted privately owned for specific family groups. Crypts – though not always, for interment, its central feature is a single, prominent pillar or column made of stone. Rock-cut tomb – a form widespread in the ancient world, in which the tomb is not built but carved out of the rock and can be a free-standing building but is more a cave, which may be extensive and may or may not have an elaborate facade. Sarcophagus – a stone container for a body or coffin decorated and part of a monument.
Sepulchre – a cavernous rock-cut space for interment in the Jewish or Christian faiths. Samadhi – in India a tomb for a deceased saint that has a larger building over it as a shrine Other forms of archaeological "tombs", such as ship burials Tumulus – A mound of earth and stones raised over a grave or graves. Tumuli are known as barrows, burial mounds, Hügelgräber or kurgans', can be found throughout much of the world. A cairn, might be a tumulus. A long barrow is a long tumulus for numbers of burials; as indicated, tombs are located in or under religious buildings, such as churches, or in cemeteries or churchyards. However, they may be found in catacombs, on private land or, in the case of early or pre-historic tombs, in what is today open landscape; the Daisen Kofun, the tomb of Emperor Nintoku, is the largest in the world by area. However, the Pyramid of Khufu in Egypt is the largest by volume. Cadaver tomb Church monument Death in Norse paganism English church monuments Funerary art Grave Ossuary Necropolis List of extant papal tombs List of mausolea List of non-extant papal tombs List of tombs and mausoleums Ziyarat - "visitation".
Notable examples: Dartmoor kistvaens Mausoleum at Halicarnassus Great Pyramids Taj Mahal Tomb of Alexander the Great Tomb of Genghis Khan Mausoleum of the First Qin Emperor Catacombs of Paris Catacombs of Rome The Panthéon Church of the Holy Sepulchre, which contains the empty tomb of Jesus, where he was buried and resurrected. Tomb of the Unknown Soldier United Kingdom: The Unknown Warrior France: Tomb of the Unknown Soldier beneath the Arc de Triomphe de l'Étoile United States: Tomb of the Unknown Soldier in Arlington National Cemetery Iraq: Monument to the Unknown Soldier Russia: Tomb of the Unknown Soldier in Alexander Garden, Moscow
Colombia the Republic of Colombia, is a sovereign state situated in the northwest of South America, with territories in Central America. Colombia shares a border to the northwest with Panama, to the east with Venezuela and Brazil and to the south with Ecuador and Peru, it shares its maritime limits with Costa Rica, Honduras, Jamaica and the Dominican Republic. Colombia is a unitary, constitutional republic comprising thirty-two departments, with the capital in Bogota. Colombia has been inhabited by various indigenous peoples since 12,000 BCE, including the Muisca and the Tairona, along with the Inca Empire that expanded to the southwest of the country; the Spanish arrived in 1499 and by the mid-16th century conquered and colonized much of the region, establishing the New Kingdom of Granada, with Santafé de Bogotá as its capital. Independence from Spain was achieved in 1819, but by 1830 the "Gran Colombia" Federation was dissolved, with what is now Colombia and Panama emerging as the Republic of New Granada.
The new nation experimented with federalism as the Granadine Confederation, the United States of Colombia, before the Republic of Colombia was declared in 1886. Panama seceded in 1903. Beginning in the 1960s, the country suffered from an asymmetric low-intensity armed conflict and rampant political violence, both of which escalated in the 1990s. Since 2005, there has been significant improvement in security and rule of law. Colombia is one of the most ethnically and linguistically diverse countries in the world, with its rich cultural heritage reflecting influences by indigenous peoples, European settlement, forced African migration, immigration from Europe and the Middle East. Urban centres are located in the highlands of the Andes mountains and the Caribbean coast. Colombia is among the world's 17 megadiverse countries, the most densely biodiverse per square kilometer. Colombia is a middle power and regional actor in Latin America, it is part of the CIVETS group of six leading emerging markets and a member of the UN, the WTO, the OAS, the Pacific Alliance, other international organizations.
Colombia's diversified economy is the fourth largest in Latin America, with macroeconomic stability and favorable long-term growth prospects. The name "Colombia" is derived from the last name of Christopher Columbus, it was conceived by the Venezuelan revolutionary Francisco de Miranda as a reference to all the New World, but to those portions under Spanish rule. The name was adopted by the Republic of Colombia of 1819, formed from the territories of the old Viceroyalty of New Granada; when Venezuela and Cundinamarca came to exist as independent states, the former Department of Cundinamarca adopted the name "Republic of New Granada". New Granada changed its name in 1858 to the Granadine Confederation. In 1863 the name was again changed, this time to United States of Colombia, before adopting its present name – the Republic of Colombia – in 1886. To refer to this country, the Colombian government uses the terms Colombia and República de Colombia. Owing to its location, the present territory of Colombia was a corridor of early human migration from Mesoamerica and the Caribbean to the Andes and Amazon basin.
The oldest archaeological finds are from the Pubenza and El Totumo sites in the Magdalena Valley 100 kilometres southwest of Bogotá. These sites date from the Paleoindian period. At Puerto Hormiga and other sites, traces from the Archaic Period have been found. Vestiges indicate that there was early occupation in the regions of El Abra and Tequendama in Cundinamarca; the oldest pottery discovered in the Americas, found at San Jacinto, dates to 5000–4000 BCE. Indigenous people inhabited the territory, now Colombia by 12,500 BCE. Nomadic hunter-gatherer tribes at the El Abra, Tibitó and Tequendama sites near present-day Bogotá traded with one another and with other cultures from the Magdalena River Valley. Between 5000 and 1000 BCE, hunter-gatherer tribes transitioned to agrarian societies. Beginning in the 1st millennium BCE, groups of Amerindians including the Muisca, Zenú, Tairona developed the political system of cacicazgos with a pyramidal structure of power headed by caciques; the Muisca inhabited the area of what is now the Departments of Boyacá and Cundinamarca high plateau where they formed the Muisca Confederation.
They farmed maize, potato and cotton, traded gold, blankets, ceramic handicrafts and rock salt with neighboring nations. The Tairona inhabited northern Colombia in the isolated mountain range of Sierra Nevada de Santa Marta; the Quimbaya inhabited regions of the Cauca River Valley between the Western and Central Ranges of the Colombian Andes. Most of the Amerindians practiced agriculture and the social structure of each indigenous community was different; some groups of indigenous people such as the Caribs lived in a state of permanent war, but others had less bellicose attitudes. The Incas expanded their empire onto the southwest part of the country. Alonso de Ojeda reached the Guajira Peninsula in 1499. Spanish explorers, led by Rodrigo de Bastidas, made the first exploration
Irrigation is the application of controlled amounts of water to plants at needed intervals. Irrigation helps to grow agricultural crops, maintain landscapes, revegetate disturbed soils in dry areas and during periods of less than average rainfall. Irrigation has other uses in crop production, including frost protection, suppressing weed growth in grain fields and preventing soil consolidation. In contrast, agriculture that relies only on direct rainfall is referred to as rain-fed or dry land farming. Irrigation systems are used for cooling livestock, dust suppression, disposal of sewage, in mining. Irrigation is studied together with drainage, the removal of surface and sub-surface water from a given area. Irrigation has been a central feature of agriculture for over 5,000 years and is the product of many cultures, it was the basis for economies and societies across the globe, from Asia to the Southwestern United States. Archaeological investigation has found evidence of irrigation in areas lacking sufficient natural rainfall to support crops for rainfed agriculture.
The earliest known use of the technology dates to the 6th millennium BCE in Khuzistan in the south-west of present-day Iran. Irrigation was used as a means of manipulation of water in the alluvial plains of the Indus valley civilization, the application of it is estimated to have begun around 4500 BC and drastically increased the size and prosperity of their agricultural settlements; the Indus Valley Civilization developed sophisticated irrigation and water-storage systems, including artificial reservoirs at Girnar dated to 3000 BCE, an early canal irrigation system from c. 2600 BCE. Large-scale agriculture was practiced, with an extensive network of canals used for the purpose of irrigation. Farmers in the Mesopotamian plain used irrigation from at least the third millennium BCE, they developed perennial irrigation watering crops throughout the growing season by coaxing water through a matrix of small channels formed in the field. Ancient Egyptians practiced basin irrigation using the flooding of the Nile to inundate land plots, surrounded by dykes.
The flood water remained until the fertile sediment had settled before the engineers returned the surplus to the watercourse. There is evidence of the ancient Egyptian pharaoh Amenemhet III in the twelfth dynasty using the natural lake of the Faiyum Oasis as a reservoir to store surpluses of water for use during dry seasons; the lake swelled annually from the flooding of the Nile. The Ancient Nubians developed a form of irrigation by using a waterwheel-like device called a sakia. Irrigation began in Nubia some time between the third and second millennia BCE, it depended upon the flood waters that would flow through the Nile River and other rivers in what is now the Sudan. In sub-Saharan Africa irrigation reached the Niger River region cultures and civilizations by the first or second millennium BCE and was based on wet-season flooding and water harvesting. Evidence of terrace irrigation occurs in pre-Columbian America, early Syria and China. In the Zana Valley of the Andes Mountains in Peru, archaeologists have found remains of three irrigation canals radiocarbon-dated from the 4th millennium BCE, the 3rd millennium BCE and the 9th century CE.
These canals provide the earliest record of irrigation in the New World. Traces of a canal dating from the 5th millennium BCE were found under the 4th-millennium canal. Ancient Persia used irrigation as far back as the 6th millennium BCE to grow barley in areas with insufficient natural rainfall; the Qanats, developed in ancient Persia about 800 BCE, are among the oldest known irrigation methods still in use today. They are now found in the Middle East and North Africa; the system comprises a network of vertical wells and sloping tunnels driven into the sides of cliffs and of steep hills to tap groundwater. The noria, a water wheel with clay pots around the rim powered by the flow of the stream, first came into use at about this time among Roman settlers in North Africa. By 150 BCE the pots were fitted with valves to allow smoother filling as they were forced into the water; the irrigation works of ancient Sri Lanka, the earliest dating from about 300 BCE in the reign of King Pandukabhaya, under continuous development for the next thousand years, were one of the most complex irrigation systems of the ancient world.
In addition to underground canals, the Sinhalese were the first to build artificial reservoirs to store water. These reservoirs and canal systems were used to irrigate paddy fields, which require a lot of water to cultivate. Most of these irrigation systems still exist undamaged up to now, in Anuradhapura and Polonnaruwa, because of the advanced and precise engineering; the system was further extended during the reign of King Parakrama Bahu. The oldest known hydraulic engineers of China were Sunshu Ao of the Spring and Autumn period and Ximen Bao of the Warring States period, both of whom worked on large irrigation projects. In the Sichuan region belonging to the state of Qin of ancient China, the Dujiangyan Irrigation System devised by the Qin Chinese hydrologist and irrigation engineer Li Bing was built in 256 BCE to irrigate a vast area of farmland that today still supplies water. By the 2nd century AD, during the Han Dynasty, the Chinese used chain pumps which lifted water from a lower elevation to a higher one.
These were powered by manual foot-pedal, hydraulic waterwheels, or rotating mechanical wheels pulled by oxen. The water was used for public works, providing water for urban residential quarters and palace gardens, bu
Spain the Kingdom of Spain, is a country located in Europe. Its continental European territory is situated on the Iberian Peninsula, its territory includes two archipelagoes: the Canary Islands off the coast of Africa, the Balearic Islands in the Mediterranean Sea. The African enclaves of Ceuta, Peñón de Vélez de la Gomera make Spain the only European country to have a physical border with an African country. Several small islands in the Alboran Sea are part of Spanish territory; the country's mainland is bordered to the south and east by the Mediterranean Sea except for a small land boundary with Gibraltar. With an area of 505,990 km2, Spain is the largest country in Southern Europe, the second largest country in Western Europe and the European Union, the fourth largest country in the European continent. By population, Spain is the fifth in the European Union. Spain's capital and largest city is Madrid. Modern humans first arrived in the Iberian Peninsula around 35,000 years ago. Iberian cultures along with ancient Phoenician, Greek and Carthaginian settlements developed on the peninsula until it came under Roman rule around 200 BCE, after which the region was named Hispania, based on the earlier Phoenician name Spn or Spania.
At the end of the Western Roman Empire the Germanic tribal confederations migrated from Central Europe, invaded the Iberian peninsula and established independent realms in its western provinces, including the Suebi and Vandals. The Visigoths would forcibly integrate all remaining independent territories in the peninsula, including Byzantine provinces, into the Kingdom of Toledo, which more or less unified politically and all the former Roman provinces or successor kingdoms of what was documented as Hispania. In the early eighth century the Visigothic Kingdom fell to the Moors of the Umayyad Islamic Caliphate, who arrived to rule most of the peninsula in the year 726, leaving only a handful of small Christian realms in the north and lasting up to seven centuries in the Kingdom of Granada; this led to many wars during a long reconquering period across the Iberian Peninsula, which led to the creation of the Kingdom of Leon, Kingdom of Castile, Kingdom of Aragon and Kingdom of Navarre as the main Christian kingdoms to face the invasion.
Following the Moorish conquest, Europeans began a gradual process of retaking the region known as the Reconquista, which by the late 15th century culminated in the emergence of Spain as a unified country under the Catholic Monarchs. Until Aragon had been an independent kingdom, which had expanded toward the eastern Mediterranean, incorporating Sicily and Naples, had competed with Genoa and Venice. In the early modern period, Spain became the world's first global empire and the most powerful country in the world, leaving a large cultural and linguistic legacy that includes more than 570 million Hispanophones, making Spanish the world's second-most spoken native language, after Mandarin Chinese. During the Golden Age there were many advancements in the arts, with world-famous painters such as Diego Velázquez; the most famous Spanish literary work, Don Quixote, was published during the Golden Age. Spain hosts the world's third-largest number of UNESCO World Heritage Sites. Spain is a secular parliamentary democracy and a parliamentary monarchy, with King Felipe VI as head of state.
It is a major developed country and a high income country, with the world's fourteenth largest economy by nominal GDP and sixteenth largest by purchasing power parity. It is a member of the United Nations, the European Union, the Eurozone, the Council of Europe, the Organization of Ibero-American States, the Union for the Mediterranean, the North Atlantic Treaty Organization, the Organisation for Economic Co-operation and Development, Organization for Security and Co-operation in Europe, the Schengen Area, the World Trade Organization and many other international organisations. While not an official member, Spain has a "Permanent Invitation" to the G20 summits, participating in every summit, which makes Spain a de facto member of the group; the origins of the Roman name Hispania, from which the modern name España was derived, are uncertain due to inadequate evidence, although it is documented that the Phoenicians and Carthaginians referred to the region as Spania, therefore the most accepted etymology is a Semitic-Phoenician one.
Down the centuries there have been a number of accounts and hypotheses: The Renaissance scholar Antonio de Nebrija proposed that the word Hispania evolved from the Iberian word Hispalis, meaning "city of the western world". Jesús Luis Cunchillos argues that the root of the term span is the Phoenician word spy, meaning "to forge metals". Therefore, i-spn-ya would mean "the land where metals are forged", it may be a derivation of the Phoenician I-Shpania, meaning "island of rabbits", "land of rabbits" or "edge", a reference to Spain's location at the end of the Mediterranean. The word in question means "Hyrax" due to Phoenicians confusing the two animals. Hispania may derive from the poetic use of the term Hesperia, reflecting the Greek perception of Italy as a "western land" or "land of the setting sun" (Hesperia
A cove is a small type of bay or coastal inlet. Coves have narrow, restricted entrances, are circular or oval, are situated within a larger bay. Small, sheltered bays, creeks, or recesses in a coast are considered coves. Colloquially, the term can be used to describe a sheltered bay. Geomorphology describes coves as precipitously-walled and rounded cirque-like openings as in a valley extending into or down a mountainside, or in a hollow or nook of a cliff or steep mountainside. A cove can refer to a corner, nook, or cranny, either in a river, road, or wall where the wall meets the floor. A notable example is Lulworth Cove on the Jurassic Coast in England. To its west, a second cove, Stair Hole, is forming. Coves are formed by differential erosion, which occurs when softer rocks are worn away faster than the harder rocks surrounding them; these rocks further erode to form a circular bay with a narrow entrance, called a cove. Jackson, Julia A. Glossary of Geology. Alexandria, VA: American Geological Institute.
Pp. 146–147. ISBN 0-922152-34-9. Clark, John O. E.. The Facts on File: Dictionary of Earth Science. New York: Market House Books Ltd