The reindeer known as the caribou in North America, is a species of deer with circumpolar distribution, native to Arctic, sub-Arctic, tundra and mountainous regions of northern Europe and North America. This includes both migratory populations. Rangifer herd size varies in different geographic regions; the Taimyr herd of migrating Siberian tundra reindeer in Russia is the largest wild reindeer herd in the world, varying between 400,000 and 1,000,000. What was once the second largest herd is the migratory boreal woodland caribou George River herd in Canada, with former variations between 28,000 and 385,000; as of January 2018, there are fewer than 9,000 animals estimated to be left in the George River herd, as reported by the Canadian Broadcasting Corporation. The New York Times reported in April 2018 of the disappearance of the only herd of southern mountain caribou in the lower 48 states, with an expert calling it "functionally extinct" after the herd's size dwindled to a mere three animals.
Rangifer varies in size and colour from the smallest, the Svalbard reindeer, to the largest, the boreal woodland caribou. The North American range of caribou extends from Alaska through Yukon, the Northwest Territories and Nunavut into the boreal forest and south through the Canadian Rockies and the Columbia and Selkirk Mountains; the Barren-ground caribou, Porcupine caribou, Peary caribou live in the tundra, while the shy boreal woodland caribou prefer the boreal forest. The Porcupine caribou and the barren-ground caribou form large herds and undertake lengthy seasonal migrations from birthing grounds to summer and winter feeding grounds in the tundra and taiga; the migrations of Porcupine caribou herds are among the longest of any mammal. Barren-ground caribou are found in Kitaa in Greenland, but the larger herds are in Alaska, the Northwest Territories, Nunavut; some subspecies are rare and at least one has become extinct: the Queen Charlotte Islands caribou of Canada. The range of the sedentary boreal woodland caribou covered more than half of Canada and into the northern States in the U.
S. Woodland caribou have disappeared from most of their original southern range and were designated as threatened in 2002 by the Committee on the Status of Endangered Wildlife in Canada. Environment Canada reported in 2011 that there were 34,000 boreal woodland caribou in 51 ranges remaining in Canada.. Siberian tundra reindeer herds are in decline, Rangifer tarandus is considered to be vulnerable by the IUCN. Arctic peoples have depended on caribou for food and shelter, such as the Caribou Inuit, the inland-dwelling Inuit of the Kivalliq Region in northern Canada, the Caribou Clan in Yukon, the Inupiat, the Inuvialuit, the Hän, the Northern Tutchone, the Gwich'in. Hunting wild reindeer and herding of semi-domesticated reindeer are important to several Arctic and sub-Arctic peoples such as the Duhalar for meat, antlers and transportation; the Sami people have depended on reindeer herding and fishing for centuries. In Lapland, reindeer pull pulks. Male and female reindeer can grow antlers annually, although the proportion of females that grow antlers varies between population and season.
Antlers are larger on males. In traditional festive legend, Santa Claus's reindeer pull a sleigh through the night sky to help Santa Claus deliver gifts to good children on Christmas Eve. Carl Linnaeus chose the name Rangifer for the reindeer genus, which Albertus Magnus used in his De animalibus, fol. Liber 22, Cap. 268: "Dicitur Rangyfer quasi ramifer". This word may go back to the Saami word raingo. Linnaeus chose the word tarandus as the specific epithet, making reference to Ulisse Aldrovandi's Quadrupedum omnium bisulcorum historia fol. 859–863, Cap. 30: De Tarando. However and Konrad Gesner – thought that rangifer and tarandus were two separate animals. In any case, the tarandos name goes back to Theophrastus; the use of the terms Reindeer and caribou for the same animal can cause confusion, but the IUCN delineates the issue: "The world's Caribou and Reindeer are classified as a single species Rangifer tarandus. Reindeer is the European name for the species while in North America, the species is known as Caribou."
The word rein is of Norse origin. The word deer was broader in meaning, but became more specific over time. In Middle English, der meant a wild animal of any kind, in contrast to cattle; the word caribou comes through French, from the Mi'kmaq qalipu, meaning "snow shoveler", referring to its habit of pawing through the snow for food. Because of its importance to many cultures, Rangifer tarandus and some of its subspecies have names in many languages. Inuktitut is spoken in the eastern Arctic, the caribou is known by the name tuktu; the Gwich’in people have over two dozen distinct caribou-related words. The species' taxonomic name, Rangifer tarandus, was defined by Carl Linnaeus in 1758; the woodland caribou subspecies' taxonomic name Rangifer tarandus caribou was defined by Gmelin in 1788. Based on Banfield's often-cited A Revision of the Reindeer and Caribou, Genus Rangifer, R. t. caboti, R. t. osborni and R. t. terraenovae were considered invalid and included in R. t. caribou. Some recent authorities have considered them all valid suggesting that they are quite distinct.
In their book entitled Mammal Species of the World, American zoologist Don E. Wilson and DeeAnn Reeder agree with Valerius Geist, specialist on large North American mammals, that
Atmospheric pressure, sometimes called barometric pressure, is the pressure within the atmosphere of Earth. The standard atmosphere is a unit of pressure defined as 1013.25 mbar, equivalent to 760 mmHg, 29.9212 inches Hg, or 14.696 psi. The atm unit is equivalent to the mean sea-level atmospheric pressure on Earth, that is, the Earth's atmospheric pressure at sea level is 1 atm. In most circumstances atmospheric pressure is approximated by the hydrostatic pressure caused by the weight of air above the measurement point; as elevation increases, there is less overlying atmospheric mass, so that atmospheric pressure decreases with increasing elevation. Pressure measures force per unit area, with SI units of Pascals. On average, a column of air with a cross-sectional area of 1 square centimetre, measured from mean sea level to the top of Earth's atmosphere, has a mass of about 1.03 kilogram and exerts a force or "weight" of about 10.1 newtons or 2.37 lbf, resulting in a pressure at sea level of about 10.1 N/cm2 or 101 kN/m2.
A column of air with a cross-sectional area of 1 in2 would have a mass of about 6.65 kg and a weight of about 65.4 N or 14.7 lbf, resulting in a pressure of 10.1 N/cm2 or 14.7 lbf/in2. Atmospheric pressure is caused by the gravitational attraction of the planet on the atmospheric gases above the surface, is a function of the mass of the planet, the radius of the surface, the amount and composition of the gases and their vertical distribution in the atmosphere, it is modified by the planetary rotation and local effects such as wind velocity, density variations due to temperature and variations in composition. The mean sea-level pressure is the average atmospheric pressure at mean sea level; this is the atmospheric pressure given in weather reports on radio and newspapers or on the Internet. When barometers in the home are set to match the local weather reports, they measure pressure adjusted to sea level, not the actual local atmospheric pressure; the altimeter setting in aviation is an atmospheric pressure adjustment.
Average sea-level pressure is 1013.25 mbar. In aviation, weather reports, QNH is transmitted around the world in millibars or hectopascals, except in the United States and Colombia where it is reported in inches of mercury; the United States and Canada report sea-level pressure SLP, adjusted to sea level by a different method, in the remarks section, not in the internationally transmitted part of the code, in hectopascals or millibars. However, in Canada's public weather reports, sea level pressure is instead reported in kilopascals. In the US weather code remarks, three digits are all; the highest sea-level pressure on Earth occurs in Siberia, where the Siberian High attains a sea-level pressure above 1050 mbar, with record highs close to 1085 mbar. The lowest measurable sea-level pressure is found at the centers of tropical cyclones and tornadoes, with a record low of 870 mbar. Surface pressure is the atmospheric pressure at a location on Earth's surface, it is directly proportional to the mass of air over that location.
For numerical reasons, atmospheric models such as general circulation models predict the nondimensional logarithm of surface pressure. The average value of surface pressure on Earth is 985 hPa; this is in contrast to mean sea-level pressure, which involves the extrapolation of pressure to sea-level for locations above or below sea-level. The average pressure at mean sea-level in the International Standard Atmosphere is 1013.25 hPa, or 1 atmosphere, or 29.92 inches of mercury. Pressure and the acceleration due to gravity, are related by P = F/A = /A, where A is surface area. Atmospheric pressure is thus proportional to the weight per unit area of the atmospheric mass above that location. Pressure on Earth varies with the altitude of the surface. Pressure varies smoothly from the Earth's surface to the top of the mesosphere. Although the pressure changes with the weather, NASA has averaged the conditions for all parts of the earth year-round; as altitude increases, atmospheric pressure decreases.
One can calculate the atmospheric pressure at a given altitude. Temperature and humidity affect the atmospheric pressure, it is necessary to know these to compute an accurate figure; the graph at right was developed for a temperature of 15 °C and a relative humidity of 0%. At low altitudes above sea level, the pressure decreases by about 1.2 kPa for every 100 metres. For higher altitudes within the troposphere, the following equation relates atmospheric pressure p to altitude h p = p 0 ⋅ g ⋅ M R 0 ⋅
The Baltic Sea is a marginal sea of the Atlantic Ocean, enclosed by Denmark, Finland, Lithuania, northeast Germany, Poland and the North and Central European Plain. The sea stretches from 53 ° N from 10 ° E to 30 ° E longitude. A mediterranean sea of the Atlantic, with limited water exchange between the two bodies, the Baltic Sea drains through the Danish islands into the Kattegat by way of the straits of Øresund, the Great Belt, the Little Belt, it includes the Gulf of Bothnia, the Bay of Bothnia, the Gulf of Finland, the Gulf of Riga, the Bay of Gdańsk. The Baltic Proper is bordered on its northern edge, at the latitude 60°N, by the Åland islands and the Gulf of Bothnia, on its northeastern edge by the Gulf of Finland, on its eastern edge by the Gulf of Riga, in the west by the Swedish part of the southern Scandinavian Peninsula; the Baltic Sea is connected by artificial waterways to the White Sea via the White Sea Canal and to the German Bight of the North Sea via the Kiel Canal. Administration The Helsinki Convention on the Protection of the Marine Environment of the Baltic Sea Area includes the Baltic Sea and the Kattegat, without calling Kattegat a part of the Baltic Sea, "For the purposes of this Convention the'Baltic Sea Area' shall be the Baltic Sea and the Entrance to the Baltic Sea, bounded by the parallel of the Skaw in the Skagerrak at 57°44.43'N."Traffic history Historically, the Kingdom of Denmark collected Sound Dues from ships at the border between the ocean and the land-locked Baltic Sea, in tandem: in the Øresund at Kronborg castle near Helsingør.
The narrowest part of Little Belt is the "Middelfart Sund" near Middelfart. Oceanography Geographers agree that the preferred physical border of the Baltic is a line drawn through the southern Danish islands, Drogden-Sill and Langeland; the Drogden Sill is situated north of Køge Bugt and connects Dragør in the south of Copenhagen to Malmö. By this definition, the Danish Straits are part of the entrance, but the Bay of Mecklenburg and the Bay of Kiel are parts of the Baltic Sea. Another usual border is the line between Falsterbo and Stevns Klint, Denmark, as this is the southern border of Øresund. It's the border between the shallow southern Øresund and notably deeper water. Hydrography and biology Drogden Sill sets a limit to Øresund and Darss Sill, a limit to the Belt Sea; the shallow sills are obstacles to the flow of heavy salt water from the Kattegat into the basins around Bornholm and Gotland. The Kattegat and the southwestern Baltic Sea have a rich biology; the remainder of the Sea is poor in oxygen and in species.
Thus, the more of the entrance, included in its definition, the healthier the Baltic appears. Tacitus called it Mare Suebicum after the Germanic people of the Suebi, Ptolemy Sarmatian Ocean after the Sarmatians, but the first to name it the Baltic Sea was the eleventh-century German chronicler Adam of Bremen; the origin of the latter name is speculative and it was adopted into Slavic and Finnic languages spoken around the sea likely due to the role of Medieval Latin in cartography. It might be connected to the Germanic word belt, a name used for two of the Danish straits, the Belts, while others claim it to be directly derived from the source of the Germanic word, Latin balteus "belt". Adam of Bremen himself compared the sea with a belt, stating that it is so named because it stretches through the land as a belt, he might have been influenced by the name of a legendary island mentioned in the Natural History of Pliny the Elder. Pliny mentions an island named Baltia with reference to accounts of Xenophon.
It is possible. Baltia might be derived from belt and mean "near belt of sea, strait." Meanwhile, others have suggested that the name of the island originates from the Proto-Indo-European root *bhel meaning "white, fair". This root and its basic meaning were retained in both Latvian. On this basis, a related hypothesis holds that the name originated from this Indo-European root via a Baltic language such as Lithuanian. Another explanation is that, while derived from the aforementioned root, the name of the sea is related to names for various forms of water and related substances in several European languages, that might have been associated with colors found in swamps, yet another explanation is that the name meant "enclosed sea, bay" as opposed to open sea. Some Swedish historians believe. In the Middle Ages the sea was known by a variety of names; the name Baltic Sea became dominant only after 1600. Usage of Baltic and similar terms to denote the region east of the sea started only in 19th century.
The Baltic Sea was known in ancient Latin language sources as Mare Suebicum or Mare Germanicum. Older native names in languages that used to be spoken on the shores of the sea or near it indicate the geographical location of the sea, or its size in relation to smaller gulfs, or tribes associated with it. In modern lang
Hadrian was Roman emperor from 117 to 138. He was born Publius Aelius Hadrianus near Santiponce, Spain into a Hispano-Roman family, his father was a first cousin of Emperor Trajan. He married Trajan's grand-niece Vibia Sabina early in his career, before Trajan became emperor and at the behest of Trajan's wife Pompeia Plotina. Plotina and Trajan's close friend and adviser Lucius Licinius Sura were well disposed towards Hadrian; when Trajan died, his widow claimed that he had nominated Hadrian as emperor before his death. Rome's military and Senate approved Hadrian's succession, but four leading senators were unlawfully put to death soon after, they had opposed Hadrian or seemed to threaten his succession, the senate held him responsible for it and never forgave him. He earned further disapproval among the elite by abandoning Trajan's expansionist policies and territorial gains in Mesopotamia, Assyria and parts of Dacia. Hadrian preferred to invest in the development of stable, defensible borders and the unification of the empire's disparate peoples.
He is known for building Hadrian's Wall. Hadrian energetically pursued personal interests, he visited every province of the Empire, accompanied by an Imperial retinue of specialists and administrators. He encouraged military preparedness and discipline, he fostered, designed, or subsidised various civil and religious institutions and building projects. In Rome itself, he constructed the vast Temple of Venus and Roma. In Egypt, he may have rebuilt the Serapeum of Alexandria, he was an ardent admirer of Greece and sought to make Athens the cultural capital of the Empire, so he ordered the construction of many opulent temples there. His intense relationship with Greek youth Antinous and Antinous' untimely death led Hadrian to establish a widespread cult late in his reign, he suppressed the Bar Kokhba revolt in Judaea. Hadrian's last years were marred by chronic illness, he saw the Bar Kokhba revolt as the failure of his panhellenic ideal. He executed two more senators for their alleged plots against him, this provoked further resentment.
His marriage to Vibia Sabina had been childless. Hadrian died the same year at Baiae, Antoninus had him deified, despite opposition from the Senate. Edward Gibbon includes him among the Empire's "Five good emperors", a "benevolent dictator", he has been described as enigmatic and contradictory, with a capacity for both great personal generosity and extreme cruelty and driven by insatiable curiosity, self-conceit, ambition. Modern interest was revived thanks to Marguerite Yourcenar's novel Mémoires d'Hadrien. Hadrian was born on 24 January 76 in Italica in the Roman province of Hispania Baetica, he was named Publius Aelius Hadrianus. His father was Publius Aelius Hadrianus Afer, a senator of praetorian rank and raised in Italica but paternally linked, through many generations over several centuries, to a family from Hadria, an ancient town in Picenum; the family had settled in Italica soon after its founding by Scipio Africanus. Hadrian's mother was Domitia Paulina, daughter of a distinguished Hispano-Roman senatorial family from Gades.
His only sibling was Aelia Domitia Paulina. Hadrian's great-nephew, Gnaeus Pedanius Fuscus Salinator, from Barcino would become Hadrian's colleague as co-consul in 118; as a senator, Hadrian's father would have spent much of his time in Rome. In terms of his career, Hadrian's most significant family connection was to Trajan, his father's first cousin, of senatorial stock, had been born and raised in Italica. Hadrian and Trajan were both considered to be – in the words of Aurelius Victor – "aliens", people "from the outside". Hadrian's parents died in 86, he and his sister became wards of Publius Acilius Attianus. Hadrian was physically active, enjoyed hunting. Hadrian's enthusiasm for Greek literature and culture earned him the nickname Graeculus. Trajan married Paulina off to the three-times consul Lucius Julius Ursus Servianus. Hadrian's first official post in Rome was as a judge at the Inheritance court, one among many vigintivirate offices at the lowest level of the cursus honorum that could lead to higher office and a senatorial career.
He served as a military tribune, first with the Legio II Adiutrix in 95 with the Legio V Macedonica. During Hadrian's second stint as tribune, the frail and aged reigning emperor Nerva adopted Trajan as his heir, he was transferred to Legio XXII Primigenia and a third tribunate. Hadrian's three tribunates gave him some career advantage. Most scions of the older senatorial families might serve one, or at most two military tribunates as a prerequisite to higher office; when Nerva died in 98, Hadrian is said to have hastened to Trajan, to inform him ahead of the official envoy sent by the go
Edward Gibbon FRS was an English historian and Member of Parliament. His most important work, The History of the Decline and Fall of the Roman Empire, was published in six volumes between 1776 and 1788 and is known for the quality and irony of its prose, its use of primary sources, its polemical criticism of organised religion. Edward Gibbon was born in 1737, the son of Edward and Judith Gibbon at Lime Grove, in the town of Putney, Surrey, he had six siblings: one sister, all of whom died in infancy. His grandfather named Edward, had lost all of his assets as a result of the South Sea Bubble stock market collapse in 1720, but regained much of his wealth. Gibbon's father was thus able to inherit a substantial estate. One of his grandparents, Catherine Acton, descended from 2nd Baronet; as a youth, Gibbon's health was under constant threat. He described himself as "a puny child, neglected by my Mother, starved by my nurse". At age nine, he was sent to Dr. Woddeson's school at Kingston upon Thames, shortly after which his mother died.
He took up residence in the Westminster School boarding house, owned by his adored "Aunt Kitty", Catherine Porten. Soon after she died in 1786, he remembered her as rescuing him from his mother's disdain, imparting "the first rudiments of knowledge, the first exercise of reason, a taste for books, still the pleasure and glory of my life". By 1751, Gibbon's reading was extensive and pointed toward his future pursuits: Laurence Echard's Roman History, William Howel's An Institution of General History, several of the 65 volumes of the acclaimed Universal History from the Earliest Account of Time. Following a stay at Bath in 1752 to improve his health, at the age of 15 Gibbon was sent by his father to Magdalen College, where he was enrolled as a gentleman-commoner, he was ill-suited, however, to the college atmosphere and rued his 14 months there as the "most idle and unprofitable" of his life. Because he himself says so in his autobiography, it used to be thought that his penchant for "theological controversy" bloomed when he came under the spell of the deist or rationalist theologian Conyers Middleton, the author of Free Inquiry into the Miraculous Powers.
In that tract, Middleton denied the validity of such powers. The product of that disagreement, with some assistance from the work of Catholic Bishop Jacques-Bénigne Bossuet, that of the Elizabethan Jesuit Robert Parsons, yielded the most memorable event of his time at Oxford: his conversion to Roman Catholicism on 8 June 1753, he was further "corrupted" by the'free thinking' deism of the playwright/poet couple David and Lucy Mallet. David Womersley has shown, that Gibbon's claim to having been converted by a reading of Middleton is unlikely, was introduced only into the final draft of the "Memoirs" in 1792–93. Bowersock suggests that Gibbon fabricated the Middleton story retrospectively in his anxiety about the impact of the French Revolution and Edmund Burke's claim that it was provoked by the French philosophes, so influential on Gibbon. Within weeks of his conversion, the adolescent was removed from Oxford and sent to live under the care and tutelage of Daniel Pavillard, Reformed pastor of Lausanne, Switzerland.
It was here that he made one of his life's two great friendships, that of Jacques Georges Deyverdun, that of John Baker Holroyd. Just a year and a half after his father threatened to disinherit him, on Christmas Day, 1754, he reconverted to Protestantism. "The various articles of the Romish creed," he wrote, "disappeared like a dream". He remained in Lausanne for five intellectually productive years, a period that enriched Gibbon's immense aptitude for scholarship and erudition: he read Latin literature, he met the one romance in his life: the daughter of the pastor of Crassy, a young woman named Suzanne Curchod, to become the wife of Louis XVI's finance minister Jacques Necker, the mother of Madame de Staël. The two developed a warm affinity. Gibbon returned to England in August 1758 to face his father. There could be no refusal of the elder's wishes. Gibbon put it this way: "I sighed as a lover, I obeyed as a son." He proceeded to cut off all contact with Curchod as she vowed to wait for him.
Their final emotional break came at Ferney, France in early 1764, though they did see each other at least one more time a year later. Upon his return to England, Gibbon published his first book, Essai sur l'Étude de la Littérature in 1761, which produced an initial taste of celebrity and distinguished him, in Paris at least, as a man of letters. From 1759 to 1770, Gibbon served on active duty and in reserve with the South Hampshire militia, his deactivation in December 1762 coinciding with the militia's dispersal at the end of the Seven Years' War; the following year he embarked on the Grand Tour. In his autobiography Gibbon vividly records his rapture when he neared "the great object of pilgrimage":...at
Soil erosion is the displacement of the upper layer of soil, one form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, ice, air, plants and humans. In accordance with these agents, erosion is sometimes divided into water erosion, glacial erosion, snow erosion, wind erosion, zoogenic erosion, anthropogenic erosion. Soil erosion may be a slow process that continues unnoticed, or it may occur at an alarming rate causing a serious loss of topsoil; the loss of soil from farmland may be reflected in reduced crop production potential, lower surface water quality and damaged drainage networks. Human activities have increased by 10 -- 40 times the rate. Excessive erosion causes both "on-site" and "off-site" problems. On-site impacts include decreases in agricultural productivity and ecological collapse, both because of loss of the nutrient-rich upper soil layers. In some cases, the eventual end result is desertification. Off-site effects include sedimentation of waterways and eutrophication of water bodies, as well as sediment-related damage to roads and houses.
Water and wind erosion are the two primary causes of land degradation. Intensive agriculture, roads, anthropogenic climate change and urban sprawl are amongst the most significant human activities in regard to their effect on stimulating erosion. However, there are many prevention and remediation practices that can curtail or limit erosion of vulnerable soils. Rainfall, the surface runoff which may result from rainfall, produces four main types of soil erosion: splash erosion, sheet erosion, rill erosion, gully erosion. Splash erosion is seen as the first and least severe stage in the soil erosion process, followed by sheet erosion rill erosion and gully erosion. In splash erosion, the impact of a falling raindrop creates a small crater in the soil, ejecting soil particles; the distance these soil particles travel can be as much as 0.6 m vertically and 1.5 m horizontally on level ground. If the soil is saturated, or if the rainfall rate is greater than the rate at which water can infiltrate into the soil, surface runoff occurs.
If the runoff has sufficient flow energy, it will transport loosened soil particles down the slope. Sheet erosion is the transport of loosened soil particles by overland flow. Rill erosion refers to the development of small, ephemeral concentrated flow paths which function as both sediment source and sediment delivery systems for erosion on hillslopes. Where water erosion rates on disturbed upland areas are greatest, rills are active. Flow depths in rills are of the order of a few centimeters or less and along-channel slopes may be quite steep; this means that rills exhibit hydraulic physics different from water flowing through the deeper, wider channels of streams and rivers. Gully erosion occurs when runoff water accumulates and flows in narrow channels during or after heavy rains or melting snow, removing soil to a considerable depth. Valley or stream erosion occurs with continued water flow along a linear feature; the erosion is both downward, deepening the valley, headward, extending the valley into the hillside, creating head cuts and steep banks.
In the earliest stage of stream erosion, the erosive activity is dominantly vertical, the valleys have a typical V cross-section and the stream gradient is steep. When some base level is reached, the erosive activity switches to lateral erosion, which widens the valley floor and creates a narrow floodplain; the stream gradient becomes nearly flat, lateral deposition of sediments becomes important as the stream meanders across the valley floor. In all stages of stream erosion, by far the most erosion occurs during times of flood, when more and faster-moving water is available to carry a larger sediment load. In such processes, it is not the water alone that erodes: suspended abrasive particles and boulders can act erosively as they traverse a surface, in a process known as traction. Bank erosion is the wearing away of the banks of a river; this is distinguished from changes on the bed of the watercourse, referred to as scour. Erosion and changes in the form of river banks may be measured by inserting metal rods into the bank and marking the position of the bank surface along the rods at different times.
Thermal erosion is the result of weakening permafrost due to moving water. It can occur both at the coast. Rapid river channel migration observed in the Lena River of Siberia is due to thermal erosion, as these portions of the banks are composed of permafrost-cemented non-cohesive materials. Much of this erosion occurs. Thermal erosion affects the Arctic coast, where wave action and near-shore temperatures combine to undercut permafrost bluffs along the shoreline and cause them to fail. Annual erosion rates along a 100-kilometre segment of the Beaufort Sea shoreline averaged 5.6 metres per year from 1955 to 2002. At high flows, kolks, or vortices are formed by large volumes of rushing water. Kolks cause extreme local erosion, plucking bedrock and creating pothole-type geographical features called Rock-cut basins. Examples can be seen in the flood regions result from glacial Lake Missoula, which created the channeled scablands in the Columbia Basin region of eastern W
Gaius Julius Caesar, known by his nomen and cognomen Julius Caesar, was a Roman politician, military general, historian who played a critical role in the events that led to the demise of the Roman Republic and the rise of the Roman Empire. He wrote Latin prose. In 60 BC, Caesar and Pompey formed the First Triumvirate, a political alliance that dominated Roman politics for several years, their attempts to amass power as Populares were opposed by the Optimates within the Roman Senate, among them Cato the Younger with the frequent support of Cicero. Caesar rose to become one of the most powerful politicians in the Roman Republic through a number of his accomplishments, notably his victories in the Gallic Wars, completed by 51 BC. During this time, Caesar became the first Roman general to cross both the English Channel and the Rhine River, when he built a bridge across the Rhine and crossed the Channel to invade Britain. Caesar's wars extended Rome's territory to past Gaul; these achievements granted him unmatched military power and threatened to eclipse the standing of Pompey, who had realigned himself with the Senate after the death of Crassus in 53 BC.
With the Gallic Wars concluded, the Senate ordered Caesar to step down from his military command and return to Rome. Leaving his command in Gaul meant losing his immunity from being charged as a criminal for waging unsanctioned wars; as a result, Caesar found himself with no other options but to cross the Rubicon with the 13th Legion, leaving his province and illegally entering Roman Italy under arms. This began Caesar's civil war, his victory in the war put him in an unrivaled position of power and influence. After assuming control of government, Caesar began a program of social and governmental reforms, including the creation of the Julian calendar, he gave citizenship to many residents of far regions of the Roman Empire. He initiated land support for veterans, he centralized the bureaucracy of the Republic and was proclaimed "dictator for life", giving him additional authority. His populist and authoritarian reforms angered the elites. On the Ides of March, 44 BC, Caesar was assassinated by a group of rebellious senators led by Gaius Cassius Longinus, Marcus Junius Brutus and Decimus Junius Brutus, who stabbed him to death.
A new series of civil wars broke out and the constitutional government of the Republic was never restored. Caesar's adopted heir Octavian known as Augustus, rose to sole power after defeating his opponents in the civil war. Octavian set about solidifying his power, the era of the Roman Empire began. Much of Caesar's life is known from his own accounts of his military campaigns and from other contemporary sources the letters and speeches of Cicero and the historical writings of Sallust; the biographies of Caesar by Suetonius and Plutarch are major sources. Caesar is considered by many historians to be one of the greatest military commanders in history, his cognomen was subsequently adopted as a synonym for "Emperor". He has appeared in literary and artistic works, his political philosophy, known as Caesarism, inspired politicians into the modern era. Gaius Julius Caesar was born into a patrician family, the gens Julia, which claimed descent from Iulus, son of the legendary Trojan prince Aeneas the son of the goddess Venus.
The Julii were of Alban origin, mentioned as one of the leading Alban houses, which settled in Rome around the mid-7th century BC, after the destruction of Alba Longa. They were granted patrician status, along with other noble Alban families; the Julii existed at an early period at Bovillae, evidenced by a ancient inscription on an altar in the theatre of that town, which speaks of their offering sacrifices according to the lege Albana, or Alban rites. The cognomen "Caesar" originated, according to Pliny the Elder, with an ancestor, born by Caesarean section; the Historia Augusta suggests three alternative explanations: that the first Caesar had a thick head of hair. Caesar issued coins featuring images of elephants, suggesting that he favored this interpretation of his name. Despite their ancient pedigree, the Julii Caesares were not politically influential, although they had enjoyed some revival of their political fortunes in the early 1st century BC. Caesar's father called Gaius Julius Caesar, governed the province of Asia, his sister Julia, Caesar's aunt, married Gaius Marius, one of the most prominent figures in the Republic.
His mother, Aurelia Cotta, came from an influential family. Little is recorded of Caesar's childhood. In 85 BC, Caesar's father died so Caesar was the head of the family at 16, his coming of age coincided with a civil war between his uncle Gaius Marius and his rival Lucius Cornelius Sulla. Both sides carried out bloody purges of their political opponents whenever they were in the ascendancy. Marius and his ally Lucius Cornelius Cinna were in control of the city when Caesar was nominated as the new Flamen Dialis, he was married to Cinna's daughter Cornelia. Following Sulla's final victory, Caesar's connections to the old regime made him a target for the new one, he was stripped of his inheritance, his wife's dowry, his priesthood, but he refused to divorce Cornelia and was forced to go into hiding. The threat against hi