Population density is a measurement of population per unit area or unit volume. It is applied to living organisms, most of the time to humans, it is a key geographical term. In simple terms population density refers to the number of people living in an area per kilometer square. Population density is population divided by total land water volume, as appropriate. Low densities may lead to further reduced fertility; this is called the Allee effect after the scientist. Examples of the causes in low population densities include: Increased problems with locating sexual mates Increased inbreeding For humans, population density is the number of people per unit of area quoted per square kilometer or square mile; this may be calculated for a county, country, another territory or the entire world. The world's population is around 7,500,000,000 and Earth's total area is 510,000,000 square kilometers. Therefore, the worldwide human population density is around 7,500,000,000 ÷ 510,000,000 = 14.7 per km2. If only the Earth's land area of 150,000,000 km2 is taken into account human population density is 50 per km2.
This includes all continental and island land area, including Antarctica. If Antarctica is excluded population density rises to over 55 people per km2. However, over half of the Earth's land mass consists of areas inhospitable to human habitation, such as deserts and high mountains, population tends to cluster around seaports and fresh-water sources. Thus, this number by itself does not give any helpful measurement of human population density. Several of the most densely populated territories in the world are city-states and dependencies; these territories have a small area and a high urbanization level, with an economically specialized city population drawing on rural resources outside the area, illustrating the difference between high population density and overpopulation The potential to maintain the agricultural aspects of deserts is limited as there is not enough precipitation to support a sustainable land. The population in these areas are low. Therefore, cities in the Middle East, such as Dubai, have been increasing in population and infrastructure growth at a fast pace.
Cities with high population densities are, by some, considered to be overpopulated, though this will depend on factors like quality of housing and infrastructure and access to resources. Most of the most densely populated cities are in Southeast Asia, though Cairo and Lagos in Africa fall into this category. City population and area are, however dependent on the definition of "urban area" used: densities are invariably higher for the central city area than when suburban settlements and the intervening rural areas are included, as in the areas of agglomeration or metropolitan area, the latter sometimes including neighboring cities. For instance, Milwaukee has a greater population density when just the inner city is measured, the surrounding suburbs excluded. In comparison, based on a world population of seven billion, the world's inhabitants, as a loose crowd taking up ten square feet per person, would occupy a space a little larger than Delaware's land area; the Gaza Strip has a population density of 5,046 pop/km.
Although arithmetic density is the most common way of measuring population density, several other methods have been developed to provide a more accurate measure of population density over a specific area. Arithmetic density: The total number of people / area of land Physiological density: The total population / area of arable land Agricultural density: The total rural population / area of arable land Residential density: The number of people living in an urban area / area of residential land Urban density: The number of people inhabiting an urban area / total area of urban land Ecological optimum: The density of population that can be supported by the natural resources Demography Human geography Idealized population Optimum population Population genetics Population health Population momentum Population pyramid Rural transport problem Small population size Distance sampling List of population concern organizations List of countries by population density List of cities by population density List of city districts by population density List of English districts by population density List of European cities proper by population density List of United States cities by population density List of islands by population density List of U.
S. states by population density List of Australian suburbs by population density Selected Current and Historic City, Ward & Neighborhood Density Duncan Smith / UCL Centre for Advanced Spatial Analysis. "World Population Density". Exploratory map shows data from the Global Human Settlement Layer produced by the European Commission JRC and the CIESIN Columbia University
Brigham Young University
Brigham Young University is a private, non-profit research university in Provo, United States owned by The Church of Jesus Christ of Latter-day Saints and run under the auspices of its Church Educational System. 99 percent of the students are members of the LDS Church and one-third of its U. S. students are from Utah. The university's primary focus is on undergraduate education, but it has 68 master's and 25 doctoral degree programs. Students attending BYU agree to follow an honor code, which mandates behavior in line with LDS teachings such as academic honesty, adherence to dress and grooming standards, abstinence from extramarital sex and from the consumption of drugs and alcohol; the university curriculum includes religious education, with required courses in, the Bible, LDS scripture and history, the university sponsors weekly devotional assemblies with most speakers addressing religious topics. Many students either delay enrollment or take a hiatus from their studies to serve as LDS missionaries.
An education at BYU is less expensive than at similar private universities, since "a significant portion" of the cost of operating the university is subsidized by the church's tithing funds. BYU offers a variety of academic programs, including liberal arts, agriculture, management and mathematical sciences and law; the university is broadly organized into 11 colleges or schools at its main Provo campus, with certain colleges and divisions defining their own admission standards. The university administers two satellite campuses, one in Jerusalem and one in Salt Lake City, while its parent organization, the Church Educational System, sponsors sister schools in Hawaii and Idaho. BYU's athletic teams compete in Division I of the NCAA and are collectively known as the BYU Cougars, their college football team is an NCAA Division I Independent, while their other sports teams compete in either the West Coast Conference or Mountain Pacific Sports Federation. BYU's sports teams have won a total of fourteen national championships.
Brigham Young University's origin can be traced back to 1862 when a man named Warren Dusenberry started a Provo school in Cluff Hall, a prominent adobe building in the northeast corner of 200 East and 200 North. After some financial difficulties the school was recreated in the Kinsey and Lewis buildings on Center street in Provo, after gaining some recognition for its quality, was adopted to become the Timpanogos branch of the University of Deseret; when financial difficulty forced another closure, on October 16, 1875, Brigham Young president of the LDS Church, deeded the property to trustees to create Brigham Young Academy after earlier hinting a school would be built in Draper, Utah, in 1867. Hence, October 16, 1875, is held as BYU's founding date. Brigham Young had been envisioning for several years the concept of a church university. Said Young about his vision: "I hope to see an Academy established in Provo... at which the children of the Latter-day Saints can receive a good education unmixed with the pernicious atheistic influences that are found in so many of the higher schools of the country."
Brigham Young Academy classes commenced on January 3, 1876. Warren Dusenberry served as interim principal for several months until April 1876 when Brigham Young's choice for principal arrived—a German immigrant named Karl Maeser. Under Maeser's direction, the school educated many luminaries including future U. S. Supreme Court Justice George Sutherland and future U. S. Senator Reed Smoot; the school, did not become a university until the end of Benjamin Cluff's term at the helm of the institution. At that time, the school was still supported by members of the community and was not absorbed and sponsored by the LDS Church until July 18, 1896. A series of odd managerial decisions by Cluff led to his demotion; the suggestion received a large amount of opposition, with many members of the Board saying the school wasn't large enough to be a university, but the decision passed. One opponent to the decision, Anthon H. Lund said, "I hope their head will grow big enough for their hat."In 1903 Brigham Young Academy was dissolved, was replaced by two institutions: Brigham Young High School, Brigham Young University.
The BY High School class of 1907 was responsible for the famous giant "Y", to this day embedded on a mountain near campus. The Board elected George H. Brimhall as the new President of BYU, he had not received a high school education. He was an excellent orator and organizer. Under his tenure in 1904 the new Brigham Young University bought 17 acres of land from Provo called "Temple Hill". After some controversy among locals over BYU's purchase of this property, construction began in 1909 on the first building on the current campus, the Karl G. Maeser Memorial. Brimhall presided over the University during a brief crisis involving the theory of evolution; the religious nature of the school seemed at the time to collide with this scientific theory. Joseph F. Smith, LDS Church president, settled the question for a time by asking that evolution not be taught at the school. A few have described the school at this time as nothing more than a "religious seminary". However, many of its graduates at this time would go on to great success and become well renowned in their fields.
Franklin S. Harris was appointed the university's president in 1921, he was the first BYU president to have a doctoral degree. Harris made several
Per capita income
Per capita income or average income measures the average income earned per person in a given area in a specified year. It is calculated by dividing the area's total income by its total population. Per capita income is national income divided by population size. Per capita income is used to measure an area's average income and compare the wealth of different populations. Per capita income is used to measure a country's standard of living, it is expressed in terms of a used international currency such as the euro or United States dollar, is useful because it is known, is calculable from available gross domestic product and population estimates, produces a useful statistic for comparison of wealth between sovereign territories. This helps to ascertain a country's development status, it is one of the three measures for calculating the Human Development Index of a country. In the United States, it is defined by the U. S. Census Bureau as the following: "Per capita income is the mean money income received in the past 12 months computed for every man and child in a geographic area."
Critics claim that per capita income has several weaknesses in measuring prosperity: Comparisons of per capita income over time need to consider inflation. Without adjusting for inflation, figures tend to overstate the effects of economic growth. International comparisons can be distorted by cost of living differences not reflected in exchange rates. Where the objective is to compare living standards between countries, adjusting for differences in purchasing power parity will more reflect what people are able to buy with their money, it does not reflect income distribution. If a country's income distribution is skewed, a small wealthy class can increase per capita income while the majority of the population has no change in income. In this respect, median income is more useful when measuring of prosperity than per capita income, as it is less influenced by outliers. Non-monetary activity, such as barter or services provided within the family, is not counted; the importance of these services varies among economies.
Per capita income does not consider whether income is invested in factors to improve the area's development, such as health, education, or infrastructure. List of countries by average wage List of countries by GDP per capita—GDP at market or government official exchange rates per inhabitant List of countries by GDP per capita—GDP calculated at purchasing power parity exchange per inhabitant List of countries by GNI per capita List of countries by GNI per capita List of countries by income equality Total personal income
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation include drizzle, sleet, snow and hail. Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor, so that the water condenses and "precipitates", thus and mist are not precipitation but suspensions, because the water vapor does not condense sufficiently to precipitate. Two processes acting together, can lead to air becoming saturated: cooling the air or adding water vapor to the air. Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called "showers."Moisture, lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed into clouds and rain. This process is active when freezing rain occurs. A stationary front is present near the area of freezing rain and serves as the foci for forcing and rising air.
Provided necessary and sufficient atmospheric moisture content, the moisture within the rising air will condense into clouds, namely stratus and cumulonimbus. The cloud droplets will grow large enough to form raindrops and descend toward the Earth where they will freeze on contact with exposed objects. Where warm water bodies are present, for example due to water evaporation from lakes, lake-effect snowfall becomes a concern downwind of the warm lakes within the cold cyclonic flow around the backside of extratropical cyclones. Lake-effect snowfall can be locally heavy. Thundersnow is possible within lake effect precipitation bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation. On the leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. Most precipitation is caused by convection; the movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes.
Precipitation is a major component of the water cycle, is responsible for depositing the fresh water on the planet. 505,000 cubic kilometres of water falls as precipitation each year. Given the Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres, but over land it is only 715 millimetres. Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Precipitation may occur on other celestial bodies, e.g. when it gets cold, Mars has precipitation which most takes the form of frost, rather than rain or snow. Precipitation is a major component of the water cycle, is responsible for depositing most of the fresh water on the planet. 505,000 km3 of water falls as precipitation each year, 398,000 km3 of it over the oceans. Given the Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres. Mechanisms of producing precipitation include convective and orographic rainfall.
Convective processes involve strong vertical motions that can cause the overturning of the atmosphere in that location within an hour and cause heavy precipitation, while stratiform processes involve weaker upward motions and less intense precipitation. Precipitation can be divided into three categories, based on whether it falls as liquid water, liquid water that freezes on contact with the surface, or ice. Mixtures of different types of precipitation, including types in different categories, can fall simultaneously. Liquid forms of precipitation include drizzle. Rain or drizzle that freezes on contact within a subfreezing air mass is called "freezing rain" or "freezing drizzle". Frozen forms of precipitation include snow, ice needles, ice pellets and graupel; the dew point is the temperature to which a parcel must be cooled in order to become saturated, condenses to water. Water vapor begins to condense on condensation nuclei such as dust and salt in order to form clouds. An elevated portion of a frontal zone forces broad areas of lift, which form clouds decks such as altostratus or cirrostratus.
Stratus is a stable cloud deck which tends to form when a cool, stable air mass is trapped underneath a warm air mass. It can form due to the lifting of advection fog during breezy conditions. There are four main mechanisms for cooling the air to its dew point: adiabatic cooling, conductive cooling, radiational cooling, evaporative cooling. Adiabatic cooling occurs when air expands; the air can rise due to convection, large-scale atmospheric motions, or a physical barrier such as a mountain. Conductive cooling occurs when the air comes into contact with a colder surface by being blown from one surface to another, for example from a liquid water surface to colder land. Radiational cooling occurs due to the emission of infrared radiation, either by the air or by the surface underneath. Evaporative cooling occurs when moisture is added to the air through evaporation, which forces the air temperature to cool to its wet-bulb temperature, or until it reaches saturation; the main ways water vapor is added to the air are: wind convergence into areas of upward motion, precipitation or virga falling from above, daytime heating evaporating water from the surface of oceans, water bodies or wet lan
United States Army
The United States Army is the land warfare service branch of the United States Armed Forces. It is one of the seven uniformed services of the United States, is designated as the Army of the United States in the United States Constitution; as the oldest and most senior branch of the U. S. military in order of precedence, the modern U. S. Army has its roots in the Continental Army, formed to fight the American Revolutionary War —before the United States of America was established as a country. After the Revolutionary War, the Congress of the Confederation created the United States Army on 3 June 1784 to replace the disbanded Continental Army; the United States Army considers itself descended from the Continental Army, dates its institutional inception from the origin of that armed force in 1775. As a uniformed military service, the U. S. Army is part of the Department of the Army, one of the three military departments of the Department of Defense; the U. S. Army is headed by a civilian senior appointed civil servant, the Secretary of the Army and by a chief military officer, the Chief of Staff of the Army, a member of the Joint Chiefs of Staff.
It is the largest military branch, in the fiscal year 2017, the projected end strength for the Regular Army was 476,000 soldiers. S. Army was 1,018,000 soldiers; as a branch of the armed forces, the mission of the U. S. Army is "to fight and win our Nation's wars, by providing prompt, land dominance, across the full range of military operations and the spectrum of conflict, in support of combatant commanders"; the branch participates in conflicts worldwide and is the major ground-based offensive and defensive force of the United States. The United States Army serves as the land-based branch of the U. S. Armed Forces. Section 3062 of Title 10, U. S. Code defines the purpose of the army as: Preserving the peace and security and providing for the defense of the United States, the Commonwealths and possessions and any areas occupied by the United States Supporting the national policies Implementing the national objectives Overcoming any nations responsible for aggressive acts that imperil the peace and security of the United StatesIn 2018, the Army Strategy 2018 articulated an eight-point addendum to the Army Vision for 2028.
While the Army Mission remains constant, the Army Strategy builds upon the Army's Brigade Modernization by adding focus to Corps and Division-level echelons. Modernization, reform for high-intensity conflict, Joint multi-domain operations are added to the strategy, to be completed by 2028; the Continental Army was created on 14 June 1775 by the Second Continental Congress as a unified army for the colonies to fight Great Britain, with George Washington appointed as its commander. The army was led by men who had served in the British Army or colonial militias and who brought much of British military heritage with them; as the Revolutionary War progressed, French aid and military thinking helped shape the new army. A number of European soldiers came on their own to help, such as Friedrich Wilhelm von Steuben, who taught Prussian Army tactics and organizational skills; the army fought numerous pitched battles and in the South in 1780–1781, at times using the Fabian strategy and hit-and-run tactics, under the leadership of Major General Nathanael Greene, hit where the British were weakest to wear down their forces.
Washington led victories against the British at Trenton and Princeton, but lost a series of battles in the New York and New Jersey campaign in 1776 and the Philadelphia campaign in 1777. With a decisive victory at Yorktown and the help of the French, the Continental Army prevailed against the British. After the war, the Continental Army was given land certificates and disbanded in a reflection of the republican distrust of standing armies. State militias became the new nation's sole ground army, with the exception of a regiment to guard the Western Frontier and one battery of artillery guarding West Point's arsenal. However, because of continuing conflict with Native Americans, it was soon realized that it was necessary to field a trained standing army; the Regular Army was at first small and after General St. Clair's defeat at the Battle of the Wabash, the Regular Army was reorganized as the Legion of the United States, established in 1791 and renamed the United States Army in 1796; the War of 1812, the second and last war between the United States and Great Britain, had mixed results.
The U. S. Army did not conquer Canada but it did destroy Native American resistance to expansion in the Old Northwest and it validated its independence by stopping two major British invasions in 1814 and 1815. After taking control of Lake Erie in 1813, the U. S. Army seized parts of western Upper Canada, burned York and defeated Tecumseh, which caused his Western Confederacy to collapse. Following U. S. victories in the Canadian province of Upper Canada, British troops who had dubbed the U. S. Army "Regulars, by God!", were able to capture and burn Washington, defended by militia, in 1814. The regular army, however proved they were professional and capable of defeating the British army during the invasions of Plattsburgh and Baltimore, prompting British agreement on the rejected terms of a status quo ante bellum. Two weeks after a treaty was signed, Andrew Jackson defeated the British in the Battle of New Orleans and Siege of Fort St. Philip, became a national hero. U. S. troops and sailors captured HMS Cyane and Penguin in the final engagements of the war.
Per the treaty, both sides (the United S
Uintah County, Utah
Uintah County is a county in the U. S. state of Utah. As of the 2010 United States Census the population was 32,588, its county seat and largest city is Vernal. The county was named for the portion of the Ute Indian tribe. Uintah County is the largest natural gas producer in Utah, with 272 billion cubic feet produced in 2008; the Vernal, UT Micropolitan Statistical Area includes all of Uintah County. Archeologic evidence suggests that portions of the Uinta Basin have been inhabited by Archaic peoples and Fremont peoples. By the time of recorded history its inhabitants were the Ute people; the first known traverse by non-Indians was made by Fathers Dominguez and Escalante, as they sought to establish a land route between California and Spanish America. By the early nineteenth century, occasional fur trappers entered the Basin. In 1831-32 Antoine Robidoux, a French trapper licensed by the Mexican government, established a trading post near present-day Whiterocks, he abandoned the effort in 1844. In 1847 the Great Salt Lake Valley, still a property of Mexico, was first colonized by Brigham Young and his followers.
In 1861 Young dispatched an exploring party to the Uinta Basin. Young made no further effort to colonize the area. In 1861 US President Abraham Lincoln created the Uintah and Ouray Indian Reservation, reserved for the use and habitation of Utah and Colorado Indians. In the 1880s the Uncompahgre Reservation was created in the southern portion of present-day Uintah County. Ashley Valley was not part of either Reservation, by 1880 enough ranchers and farmers had settled there that the Territorial Legislature created Uintah County from portions of Sanpete and Wasatch counties, they established the county seat at Ashley, a now-abandoned settlement three miles north of the present courthouse in Vernal. Uintah County boundaries were altered in 1892, in 1917, in 1918, in 1919, it has remained in its present configuration since 1919. Gilsonite was discovered in 1888 in central Uintah County; this was on Reservation land, but miners pressured the US government to remove some 7000 acres for mining use. Mining and its associated activities boomed in that area.
The northern boundary of Uintah County extended to the north border of Utah. In 1918 the extreme northern portion was split off to form Utah. Uintah County lies on the east side of Utah, its eastern border abuts the western border of the state of Colorado. The Green River flows southwestward through the central part of the county, forms the lower part of Uintah County's border with Duchesne County. Two miles south of Ouray, Utah, it is joined by the Duchesne River, three miles farther down by the White River. Ten miles farther downstream it is joined by Willow Creek, flowing northward from the lower part of the county; the county terrain slopes to the south and to the west, with its highest parts found on the crests of the Uinta Mountains, running east-west across the north border. The maximum elevation along those crests is around 12,276'; the county has a total area of 4,501 square miles, of which 4,480 square miles is land and 22 square miles is water. Uintah County is centered in the Uintah Basin, which runs from western Colorado on the east to the Wasatch Mountains on the west, from the Uinta Mountains on the north to the Roan Plateau on the south.
This basin was formed by a prehistoric lake during the late Tertiary period. The county's geography ranges from high mountain terrain to the fertile Ashley Valley, to a rugged and desolate canyonland which includes the Dinosaur National Monument, to desolate and uninhabited hills in the south. Dyer Mine, 40°44′7.63″N 109°34′6.1″W, elevation: 9,852 feet MSL Little Water Mine, 40°32′15.37″N 109°49′20.54″W, elevation: 6,913 feet MSL Uteland Mine, 40°3′3.02″N 109°44′29.55″W, elevation 4,675 feet MSL As of the 2000 United States Census, there were 25,224 people, 8,187 households, 6,541 families in the county. The population density was 5.63/sqmi. There were 9,040 housing units at an average density of 2.02/sqmi. The racial makeup of the county was 87.73% White, 0.11% Black or African American, 9.38% Native American, 0.22% Asian, 0.08% Pacific Islander, 1.05% from other races, 1.43% from two or more races. 3.54 % of the population was Latino of any race. There were 8,187 households out of which 44.50% had children under the age of 18 living with them, 65.70% were married couples living together, 10.60% had a female householder with no husband present, 20.10% were non-families.
17.20% of all households were made up of individuals and 7.30% had someone living alone, 65 years of age or older. The average household size was 3.05 and the average family size was 3.45. The county population contained 34.60% under the age of 18, 10.70% from 18 to 24, 25.40% from 25 to 44, 19.30% from 45 to 64, 9.90% who were 65 years of age or older. The median age was 29 years. For every 100 females there were 99.30 males. For every 100 females age 18 and over
A fortification is a military construction or building designed for the defense of territories in warfare, is used to solidify rule in a region during peacetime. The term is derived from the Latin fortis and facere. From early history to modern times, walls have been necessary for cities to survive in an ever-changing world of invasion and conquest; some settlements in the Indus Valley Civilization were the first small cities to be fortified. In ancient Greece, large stone walls had been built in Mycenaean Greece, such as the ancient site of Mycenae. A Greek phrourion was a fortified collection of buildings used as a military garrison, is the equivalent of the Roman castellum or English fortress; these constructions served the purpose of a watch tower, to guard certain roads and lands that might threaten the kingdom. Though smaller than a real fortress, they acted as a border guard rather than a real strongpoint to watch and maintain the border; the art of setting out a military camp or constructing a fortification traditionally has been called "castrametation" since the time of the Roman legions.
Fortification is divided into two branches: permanent fortification and field fortification. There is an intermediate branch known as semi-permanent fortification. Castles are fortifications which are regarded as being distinct from the generic fort or fortress in that they are a residence of a monarch or noble and command a specific defensive territory. Roman forts and hill forts were the main antecedents of castles in Europe, which emerged in the 9th century in the Carolingian Empire; the Early Middle Ages saw the creation of some towns built around castles. Medieval-style fortifications were made obsolete by the arrival of cannons in the 14th century. Fortifications in the age of black powder evolved into much lower structures with greater use of ditches and earth ramparts that would absorb and disperse the energy of cannon fire. Walls exposed to direct cannon fire were vulnerable, so the walls were sunk into ditches fronted by earth slopes to improve protection; the arrival of explosive shells in the 19th century led to yet another stage in the evolution of fortification.
Star forts did not fare well against the effects of high explosive, the intricate arrangements of bastions, flanking batteries and the constructed lines of fire for the defending cannon could be disrupted by explosive shells. Steel-and-concrete fortifications were common during the early 20th centuries; however the advances in modern warfare since World War I have made large-scale fortifications obsolete in most situations. Demilitarized zones along borders are arguably another type of fortification, although a passive kind, providing a buffer between hostile militaries. Many US military installations are known as forts. Indeed, during the pioneering era of North America, many outposts on the frontiers non-military outposts, were referred to generically as forts. Larger military installations may be called fortresses; the word fortification can refer to the practice of improving an area's defence with defensive works. City walls are fortifications but are not called fortresses; the art of setting out a military camp or constructing a fortification traditionally has been called castrametation since the time of the Roman legions.
The art/science of laying siege to a fortification and of destroying it is called siegecraft or siege warfare and is formally known as poliorcetics. In some texts this latter term applies to the art of building a fortification. Fortification is divided into two branches: permanent fortification and field fortification. Permanent fortifications are erected at leisure, with all the resources that a state can supply of constructive and mechanical skill, are built of enduring materials. Field fortifications—for example breastworks—and known as fieldworks or earthworks, are extemporized by troops in the field assisted by such local labour and tools as may be procurable and with materials that do not require much preparation, such as earth and light timber, or sandbags. An example of field fortification was the construction of Fort Necessity by George Washington in 1754. There is an intermediate branch known as semi-permanent fortification; this is employed when in the course of a campaign it becomes desirable to protect some locality with the best imitation of permanent defences that can be made in a short time, ample resources and skilled civilian labour being available.
An example of this is the construction of Roman forts in England and in other Roman territories where camps were set up with the intention of staying for some time, but not permanently. Castles are fortifications which are regarded as being distinct from the generic fort or fortress in that it describes a residence of a monarch or noble and commands a specific defensive territory. An example of this is the massive medieval castle of Carcassonne. From early history to modern times, walls have been a necessity for many cities. In Bulgaria, near the town of Provadia a walled fortified settlement today called Solnitsata starting from 4700 BC had a diameter of about 300 feet, was home to 350 people living in two-storey houses, was encircled by a fortified wall; the huge walls around the settlement, which were built tall and with stone blocks which are 6 feet high and 4.5 feet thick, make it one of the earliest walled settlements in Europe but it is younger than the walled town of Sesklo in Greece from 6800 BC.
Uruk in ancient Su