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111-569: The SE (South Eastern) postcode area covers a broad area of the south-east of the London , England post town from the Albert Embankment to West Heath and the nearest edges of Sidcup and Selhurst . It loosely corresponds to the boroughs of Southwark , Lewisham and Greenwich plus indicated parts of the boroughs of Croydon (north), Lambeth (east), Bexley (west) and Bromley (northwest). The postcode area originated in 1857 as

222-472: A Bronze Age bridge were found on the south River Thames foreshore, upstream from Vauxhall Bridge . Two of the timbers were radiocarbon dated to 1750–1285 BC. In 2010, foundations of a large timber structure, dated to 4800–4500 BC, were found on the Thames' south foreshore downstream from Vauxhall Bridge. Both structures are on the south bank of the Thames, where the now-underground River Effra flows into

333-573: A harsh environment for organisms. Sediment often settles in intertidal mudflats which are extremely difficult to colonize. No points of attachment exist for algae , so vegetation based habitat is not established. Sediment can also clog feeding and respiratory structures of species, and special adaptations exist within mudflat species to cope with this problem. Lastly, dissolved oxygen variation can cause problems for life forms. Nutrient-rich sediment from human-made sources can promote primary production life cycles, perhaps leading to eventual decay removing

444-542: A larger area, similar in size to Greater London, although some outer districts are excluded and some just outside included. The Greater London boundary has been aligned to the M25 motorway in places. Further urban expansion is now prevented by the Metropolitan Green Belt , although the built-up area extends beyond the boundary in places, producing a separately defined Greater London Urban Area . Beyond this

555-529: A number of coastal water bodies such as coastal lagoons and brackish seas. A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff; however the freshwater inflow may not be perennial, the connection to the sea may be closed for part of the year and tidal influence may be negligible". This broad definition also includes fjords , lagoons , river mouths , and tidal creeks . An estuary

666-403: A population density of 802 per acre (325 per hectare). In addition to the growing number of stores selling goods, such as Harding, Howell & Co. —one of the first department stores —located on Pall Mall , the streets had scores of street sellers . London's overcrowded conditions led to cholera epidemics, claiming 14,000 lives in 1848, and 6,000 in 1866. Rising traffic congestion led to

777-573: A population of 7,172,036 in 2001 and a population density of 11,760 inhabitants per square mile (4,542/km ). The extended area known as the London Metropolitan Region or the London Metropolitan Agglomeration, comprises a total area of 3,236 square miles (8,382 km ) has a population of 13,709,000 and a population density of 3,900 inhabitants per square mile (1,510/km ). Modern London stands on

888-580: A post- Brexit exodus of stock listings from the London Stock Exchange , London remains a European economic powerhouse, and one of the world's major financial centres . It hosts Europe's largest concentration of higher education institutions , some of which are the highest-ranked academic institutions in the world: Imperial College London in natural and applied sciences , the London School of Economics in social sciences , and

999-551: A temperate oceanic climate ( Köppen : Cfb ). Rainfall records have been kept in the city since at least 1697, when records began at Kew . At Kew, the most rainfall in one month is 7.4 inches (189 mm) in November 1755 and the least is 0 inches (0 mm) in both December 1788 and July 1800. Mile End also had 0 inches (0 mm) in April 1893. The wettest year on record is 1903, with a total fall of 38.1 inches (969 mm) and

1110-408: A type of ecosystem in some estuaries that have been negatively impacted by eutrophication. Cordgrass vegetation dominates the salt marsh landscape. Excess nutrients allow the plants to grow at greater rates in above ground biomass, however less energy is allocated to the roots since nutrients is abundant. This leads to a lower biomass in the vegetation below ground which destabilizes the banks of

1221-407: A variety of factors including soil erosion , deforestation , overgrazing , overfishing and the filling of wetlands. Eutrophication may lead to excessive nutrients from sewage and animal wastes; pollutants including heavy metals , polychlorinated biphenyls , radionuclides and hydrocarbons from sewage inputs; and diking or damming for flood control or water diversion. The word "estuary"

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1332-563: A well-mixed water column and the disappearance of the vertical salinity gradient . The freshwater-seawater boundary is eliminated due to the intense turbulent mixing and eddy effects . The lower reaches of Delaware Bay and the Raritan River in New Jersey are examples of vertically homogeneous estuaries. Inverse estuaries occur in dry climates where evaporation greatly exceeds the inflow of freshwater. A salinity maximum zone

1443-436: A wholly marine embayment to any of the other estuary types. The most important variable characteristics of estuary water are the concentration of dissolved oxygen, salinity and sediment load. There is extreme spatial variability in salinity, with a range of near-zero at the tidal limit of tributary rivers to 3.4% at the estuary mouth. At any one point, the salinity will vary considerably over time and seasons, making it

1554-477: A wide effect on the surrounding water bodies.  In turn, this can decrease fishing industry sales in one area and across the country. Production in 2016 from recreational and commercial fishing contributes billions of dollars to the United States' gross domestic product (GDP). A decrease in production within this industry can affect any of the 1.7 million people the fishing industry employs yearly across

1665-699: Is 1,049.8 millibars (31.00 inHg) on 20 January 2020. Summers are generally warm, sometimes hot. London's average July high is 23.5 °C (74.3 °F). On average each year, London experiences 31 days above 25 °C (77.0 °F) and 4.2 days above 30.0 °C (86.0 °F). During the 2003 European heat wave , prolonged heat led to hundreds of heat-related deaths. A previous spell of 15 consecutive days above 32.2 °C (90.0 °F) in England in 1976 also caused many heat related deaths. A previous temperature of 37.8 °C (100.0 °F) in August 1911 at

1776-455: Is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides . The effects of tides on estuaries can show nonlinear effects on the movement of water which can have important impacts on the ecosystem and waterflow. The seawater entering the estuary is diluted by the fresh water flowing from rivers and streams. The pattern of dilution varies between different estuaries and depends on

1887-417: Is a late addition carved out of the existing districts SE2 and SE18 to reflect the building up of a new London district in what had been the meadows and marshes by the tidal Thames in the parish of Plumstead: Thamesmead . Unlike SW, where a consecutive 50%, there ten, districts can more officially be traced into two alphabetical groups excluding SW1, SE has always technically followed the norm in that SE1

1998-562: Is agreed that the name came into these languages from Common Brythonic ; recent work tends to reconstruct the lost Celtic form of the name as * Londonjon or something similar. This was then adapted into Latin as Londinium and borrowed into Old English. Until 1889, the name "London" applied officially only to the City of London , but since then it has also referred to the County of London and to Greater London . In 1993, remains of

2109-513: Is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus , meaning tide. There have been many definitions proposed to describe an estuary. The most widely accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, and within which seawater is measurably diluted with freshwater derived from land drainage". However, this definition excludes

2220-545: Is formed of two tiers: a citywide, strategic tier and a local tier. Citywide administration is coordinated by the Greater London Authority (GLA), while local administration is carried out by 33 smaller authorities. The GLA consists of two elected components: the mayor of London , who has executive powers , and the London Assembly , which scrutinises the mayor's decisions and can accept or reject

2331-411: Is formed, and both riverine and oceanic water flow close to the surface towards this zone. This water is pushed downward and spreads along the bottom in both the seaward and landward direction. Examples of an inverse estuary are Spencer Gulf , South Australia, Saloum River and Casamance River , Senegal. Estuary type varies dramatically depending on freshwater input, and is capable of changing from

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2442-760: Is headquartered in Thames House on the north bank of the River Thames and the foreign intelligence service ( MI6 ) is headquartered in the SIS Building on the south bank. Crime rates vary widely across different areas of London. Crime figures are made available nationally at Local Authority and Ward level. In 2015, there were 118 homicides, a 25.5% increase over 2014. Recorded crime has been rising in London, notably violent crime and murder by stabbing and other means have risen. There were 50 murders from

2553-592: Is held by an independent . The ministerial post of minister for London was created in 1994, however as of 2024, the post has been vacant. Policing in Greater London, with the exception of the City of London , is provided by the Metropolitan Police ("The Met"), overseen by the mayor through the Mayor's Office for Policing and Crime (MOPAC). The Met is also referred to as Scotland Yard after

2664-564: Is known as London . It is the capital of the United Kingdom and of England by convention rather than statute. The capital of England was moved to London from Winchester as the Palace of Westminster developed in the 12th and 13th centuries to become the permanent location of the royal court , and thus the political capital of the nation. Greater London encompasses a total area of 611 square miles (1,583 km ) an area which had

2775-566: Is less restricted, and there is a slow but steady exchange of water between the estuary and the ocean. Fjord-type estuaries can be found along the coasts of Alaska , the Puget Sound region of western Washington state , British Columbia , eastern Canada, Greenland , Iceland , New Zealand, and Norway. These estuaries are formed by subsidence or land cut off from the ocean by land movement associated with faulting , volcanoes , and landslides . Inundation from eustatic sea-level rise during

2886-694: Is the capital and largest city of both England and the United Kingdom , with a population of 8,866,180 in 2022. The wider metropolitan area is the largest in Western Europe , with a population of 14.9 million. London stands on the River Thames in southeast England, at the head of a 50-mile (80 km) estuary down to the North Sea , and has been a major settlement for nearly 2,000 years. Its ancient core and financial centre ,

2997-420: Is the only head district. However SE19 was drawn up to serve the key distribution office serving Norwood after a complete alphabetical series so that those surrounding it and SE21 (Dulwich): SE20 and SE22 to SE27 are strictly alphabetical afresh (Anerley to West Norwood) but it has never technically been a "head district". The postcode area is part of the London post town. There are no dependent localities used in

3108-523: Is the vast London commuter belt . Greater London is split for some purposes into Inner London and Outer London , and by the River Thames into North and South , with an informal central London area. The coordinates of the nominal centre of London, traditionally the original Eleanor Cross at Charing Cross near the junction of Trafalgar Square and Whitehall , are about 51°30′26″N 00°07′39″W  /  51.50722°N 0.12750°W  / 51.50722; -0.12750 . Within London, both

3219-646: Is the whitefish species from the European Alps . Eutrophication reduced the oxygen levels in their habitats so greatly that whitefish eggs could not survive, causing local extinctions. However, some animals, such as carnivorous fish, tend to do well in nutrient-enriched environments and can benefit from eutrophication. This can be seen in populations of bass or pikes. Eutrophication can affect many marine habitats which can lead to economic consequences. The commercial fishing industry relies upon estuaries for approximately 68 percent of their catch by value because of

3330-517: The 2012 Summer Olympics . London is an ancient name, attested in the first century AD, usually in the Latinised form Londinium . Modern scientific analyses of the name must account for the origins of the different forms found in early sources: Latin (usually Londinium ), Old English (usually Lunden ), and Welsh (usually Llundein ), with reference to the known developments over time of sounds in those different languages. It

3441-540: The Black Death in the mid-14th century, London lost nearly a third of its population. London was the focus of the Peasants' Revolt in 1381. London was a centre of England's Jewish population before their expulsion by Edward I in 1290. Violence against Jews occurred in 1190, when it was rumoured that the new king had ordered their massacre after they had presented themselves at his coronation. In 1264 during

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3552-533: The Canary Wharf development. This was born out of London's increasing role as an international financial centre in the 1980s. Located about 2 miles (3 km) east of central London, the Thames Barrier was completed in the 1980s to protect London against tidal surges from the North Sea . The Greater London Council was abolished in 1986, leaving London with no central administration until 2000 and

3663-505: The City of London , was founded by the Romans as Londinium and has retained its medieval boundaries. The City of Westminster , to the west of the City of London, has been the centuries-long host of the national government and parliament . London grew rapidly in the 19th century , becoming the world's largest city at the time . Since the 19th century, the name "London" has referred to

3774-672: The Corn Laws in 1846 was specifically aimed at weakening Dutch economic power. London then overtook Amsterdam as the leading international financial centre. With the onset of the Industrial Revolution in Britain, an unprecedented growth in urbanisation took place, and the number of High Streets (the primary street for retail in Britain) rapidly grew. London was the world's largest city from about 1831 to 1925 , with

3885-568: The Georgian era , new districts such as Mayfair were formed in the west; new bridges over the Thames encouraged development in South London . In the east, the Port of London expanded downstream. London's development as an international financial centre matured for much of the 18th century. In 1762, George III acquired Buckingham House , which was enlarged over the next 75 years. During

3996-748: The Holocene Epoch has also contributed to the formation of these estuaries. There are only a small number of tectonically produced estuaries; one example is the San Francisco Bay , which was formed by the crustal movements of the San Andreas Fault system causing the inundation of the lower reaches of the Sacramento and San Joaquin rivers . In this type of estuary, river output greatly exceeds marine input and tidal effects have minor importance. Freshwater floats on top of

4107-634: The King's Road , Chelsea and Carnaby Street . The role of trendsetter revived in the punk era. In 1965 London's political boundaries were expanded in response to the growth of the urban area and a new Greater London Council was created. During The Troubles in Northern Ireland, London was hit from 1973 by bomb attacks by the Provisional Irish Republican Army . These attacks lasted for two decades, starting with

4218-627: The London Ambulance Service (LAS) NHS Trust , the largest free-at-the-point-of-use emergency ambulance service in the world. The London Air Ambulance charity operates in conjunction with the LAS where required. Her Majesty's Coastguard and the Royal National Lifeboat Institution operate on the River Thames , which is under the jurisdiction of the Port of London Authority from Teddington Lock to

4329-610: The Mandovi estuary in Goa during the monsoon period. As tidal forcing increases, river output becomes less than the marine input. Here, current induced turbulence causes mixing of the whole water column such that salinity varies more longitudinally rather than vertically, leading to a moderately stratified condition. Examples include the Chesapeake Bay and Narragansett Bay . Tidal mixing forces exceed river output, resulting in

4440-782: The Mediterranean was normally through Antwerp and over the Alps ; any ships passing through the Strait of Gibraltar to or from England were likely to be Italian or Ragusan . The reopening of the Netherlands to English shipping in January 1565 spurred a burst of commercial activity. The Royal Exchange was founded. Mercantilism grew and monopoly traders such as the East India Company were founded as trade expanded to

4551-640: The Mid-Atlantic coast, and Galveston Bay and Tampa Bay along the Gulf Coast . Bar-built estuaries are found in a place where the deposition of sediment has kept pace with rising sea levels so that the estuaries are shallow and separated from the sea by sand spits or barrier islands. They are relatively common in tropical and subtropical locations. These estuaries are semi-isolated from ocean waters by barrier beaches ( barrier islands and barrier spits ). Formation of barrier beaches partially encloses

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4662-613: The New Model Army entered London in 1647, and they were levelled by Parliament the same year. London was plagued by disease in the early 17th century, culminating in the Great Plague of 1665–1666, which killed up to 100,000 people, or a fifth of the population. The Great Fire of London broke out in 1666 in Pudding Lane in the city and quickly swept through the wooden buildings. Rebuilding took over ten years and

4773-564: The New World . London became the main North Sea port, with migrants arriving from England and abroad. The population rose from about 50,000 in 1530 to about 225,000 in 1605. In the 16th century, William Shakespeare and his contemporaries lived in London during English Renaissance theatre . Shakespeare's Globe Theatre was constructed in 1599 in Southwark . Stage performances came to a halt in London when Puritan authorities shut down

4884-612: The Old Bailey bombing . Racial inequality was highlighted by the 1981 Brixton riot . Greater London's population declined in the decades after the Second World War, from an estimated peak of 8.6 million in 1939 to around 6.8 million in the 1980s. The principal ports for London moved downstream to Felixstowe and Tilbury , with the London Docklands area becoming a focus for regeneration, including

4995-662: The Second Barons' War , Simon de Montfort 's rebels killed 500 Jews while attempting to seize records of debts. During the Tudor period , the Reformation produced a gradual shift to Protestantism . Much of London property passed from church to private ownership, which accelerated trade and business in the city. In 1475, the Hanseatic League set up a main trading base ( kontor ) of England in London, called

5106-671: The Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border. The width-to-depth ratio of these estuaries is typically large, appearing wedge-shaped (in cross-section) in the inner part and broadening and deepening seaward. Water depths rarely exceed 30 m (100 ft). Examples of this type of estuary in the U.S. are the Hudson River , Chesapeake Bay , and Delaware Bay along

5217-585: The Stalhof or Steelyard . It remained until 1853, when the Hanseatic cities of Lübeck , Bremen and Hamburg sold the property to South Eastern Railway . Woollen cloth was shipped undyed and undressed from 14th/15th century London to the nearby shores of the Low Countries . Yet English maritime enterprise hardly reached beyond the seas of north-west Europe . The commercial route to Italy and

5328-547: The Thames , its primary geographical feature, a navigable river which crosses the city from the south-west to the east. The Thames Valley is a flood plain surrounded by gently rolling hills including Parliament Hill , Addington Hills , and Primrose Hill . Historically London grew up at the lowest bridging point on the Thames. The Thames was once a much broader, shallower river with extensive marshlands ; at high tide, its shores reached five times their present width. Since

5439-660: The Tower of London ; the site featuring the Palace of Westminster , Church of St. Margaret , and Westminster Abbey ; and the historic settlement in Greenwich where the Royal Observatory defines the prime meridian (0° longitude ) and Greenwich Mean Time . Other landmarks include Buckingham Palace , the London Eye , Piccadilly Circus , St Paul's Cathedral , Tower Bridge , and Trafalgar Square . The city has

5550-533: The Victorian era the Thames has been extensively embanked , and many of its London tributaries now flow underground . The Thames is a tidal river, and London is vulnerable to flooding. The threat has increased over time because of a slow but continuous rise in high water level caused by climate change and by the slow 'tilting' of the British Isles as a result of post-glacial rebound . London has

5661-478: The black-tailed godwit , rely on estuaries. Two of the main challenges of estuarine life are the variability in salinity and sedimentation . Many species of fish and invertebrates have various methods to control or conform to the shifts in salt concentrations and are termed osmoconformers and osmoregulators . Many animals also burrow to avoid predation and to live in a more stable sedimental environment. However, large numbers of bacteria are found within

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5772-562: The metropolis around the City of London, historically split between the counties of Middlesex , Essex , Surrey , Kent , and Hertfordshire , which since 1965 has largely comprised the administrative area of Greater London , governed by 33 local authorities and the Greater London Authority . As one of the world's major global cities , London exerts a strong influence on world art , entertainment, fashion , commerce, finance, education , healthcare , media , science, technology, tourism , transport , and communications. Despite

5883-569: The 11th century, London was clearly the largest town in England. Westminster Abbey , rebuilt in Romanesque style by King Edward the Confessor , was one of the grandest churches in Europe. Winchester had been the capital of Anglo-Saxon England , but from this time London became the main forum for foreign traders and the base for defence in time of war. In the view of Frank Stenton : "It had

5994-434: The 18th century, London was said to be dogged by crime, and the Bow Street Runners were established in 1750 as a professional police force. Epidemics during the 1720s and 30s saw most children born in the city die before reaching their fifth birthday. Coffee-houses became a popular place to debate ideas, as growing literacy and development of the printing press made news widely available, with Fleet Street becoming

6105-420: The City of London and the City of Westminster have city status . The City of London and the remainder of Greater London are both counties for the purposes of lieutenancies . The area of Greater London includes areas that are part of the historic counties of Middlesex , Kent , Surrey , Essex and Hertfordshire . More recently, Greater London has been defined as a region of England and in this context

6216-405: The Greenwich station was later disregarded as non-standard. Droughts can also, occasionally, be a problem, especially in summer, most recently in summer 2018, and with much drier than average conditions prevailing from May to December. However, the most consecutive days without rain was 73 days in the spring of 1893. Estuary Most existing estuaries formed during the Holocene epoch with

6327-435: The London area. This called for the Corporation of the city to extend its jurisdiction and administration over expanding areas around the city. Fearing an attempt by the Crown to diminish the Liberties of London , coupled with a lack of interest in administering these additional areas or concern by city guilds of having to share power, caused the Corporation's "The Great Refusal", a decision which largely continues to account for

6438-423: The SE district. In 1868 it gained some of the area of the short-lived S district, with the rest going to SW . It was divided into numbered districts in 1917, by giving the district closest to London that hosted the head office the suffix "1" and all others alphabetically based on a locally important parish, chapelry, topological or built environment feature administering or close to the local distribution office. SE28

6549-409: The Thames. Despite the evidence of scattered Brythonic settlements in the area, the first major settlement was founded by the Romans around 47 AD, about four years after their invasion of 43 AD. This only lasted until about 61 AD, when the Iceni tribe led by Queen Boudica stormed it and burnt it to the ground. The next planned incarnation of Londinium prospered, superseding Colchester as

6660-415: The United Kingdom's population and over 16% of England's population. The Greater London Built-up Area is the fourth-most populous in Europe, with about 9.8 million inhabitants as of 2011. The London metropolitan area is the third-most populous in Europe, with about 14 million inhabitants as of 2016, making London a megacity . Four World Heritage Sites are located in London: Kew Gardens ;

6771-400: The United States. Estuaries are incredibly dynamic systems, where temperature, salinity, turbidity, depth and flow all change daily in response to the tides. This dynamism makes estuaries highly productive habitats, but also make it difficult for many species to survive year-round. As a result, estuaries large and small experience strong seasonal variation in their fish communities. In winter,

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6882-405: The Viking incursions formally agreed by the Danish warlord , Guthrum and the West Saxon king Alfred the Great in 886. The Anglo-Saxon Chronicle records that Alfred "refounded" London in 886. Archaeological research shows this involved abandonment of Lundenwic and a revival of life and trade within the old Roman walls . London then grew slowly until a dramatic increase in about 950. By

6993-452: The bottom where they are harmless. Historically the oysters filtered the estuary's entire water volume of excess nutrients every three or four days. Today that process takes almost a year, and sediment, nutrients, and algae can cause problems in local waters. Some major rivers that run through deserts historically had vast, expansive estuaries that have been reduced to a fraction of their former size, because of dams and diversions. One example

7104-437: The centre of the British press. The invasion of Amsterdam by Napoleonic armies led many financiers to relocate to London and the first London international issue was arranged in 1817. Around the same time, the Royal Navy became the world's leading war fleet, acting as a major deterrent to potential economic adversaries. Following a fire in 1838, the Royal Exchange was redesigned by William Tite and rebuilt in 1844. The repeal of

7215-425: The city's metropolis. The City of London at its core once comprised the whole settlement, but as its urban area grew, the Corporation of London resisted attempts to amalgamate the city with its suburbs , causing "London" to be defined several ways. Forty per cent of Greater London is covered by the London post town , in which 'London' forms part of postal addresses. The London telephone area code (020) covers

7326-412: The city, to intimidate the inhabitants. In 1097, William II began building Westminster Hall , near the abbey. It became the basis of a new Palace of Westminster . In the 12th century, the institutions of central government, which had hitherto followed the royal English court around the country, grew in size and sophistication and became increasingly fixed, for most purposes at Westminster , although

7437-443: The combined revenue expenditure by London councils and the GLA amounted to just over £22 billion (£14.7 billion for the boroughs and £7.4 billion for the GLA). The London Fire Brigade is the statutory fire and rescue service for Greater London, run by the London Fire and Emergency Planning Authority . It is the third largest fire service in the world. National Health Service ambulance services are provided by

7548-405: The comprehensive University College London . It is the most visited city in Europe and has the world's busiest city airport system . The London Underground is the world's oldest rapid transit system. London's diverse cultures encompass over 300 languages. The 2023 population of Greater London of just under 10 million made it Europe's third-most populous city , accounting for 13.4% of

7659-500: The creation of the Greater London Authority . To mark the 21st century, the Millennium Dome , London Eye and Millennium Bridge were constructed. On 6 July 2005 London was awarded the 2012 Summer Olympics , as the first city to stage the Olympic Games three times. On 7 July 2005, three London Underground trains and a double-decker bus were bombed in a series of terrorist attacks . In 2008, Time named London alongside New York City and Hong Kong as Nylonkong , hailing them as

7770-419: The creation of the London Underground , the world's first urban rail network . The Metropolitan Board of Works oversaw infrastructure expansion in the capital and some surrounding counties; it was abolished in 1889 when the London County Council was created out of county areas surrounding the capital. From the early years of the 20th century onwards, teashops were found on High Streets across London and

7881-409: The dissolved oxygen from the water; thus hypoxic or anoxic zones can develop. Nitrogen is often the lead cause of eutrophication in estuaries in temperate zones. During a eutrophication event, biogeochemical feedback decreases the amount of available silica . These feedbacks also increase the supply of nitrogen and phosphorus, creating conditions where harmful algal blooms can persist. Given

7992-713: The driest is 1921, with a total fall of 12.1 inches (308 mm). The average annual precipitation amounts to about 600mm, which is half the annual rainfall of New York City . Despite relatively low annual precipitation, London receives 109.6 rainy days on the 1.0mm threshold annually. London is vulnerable to climate change , and there is concern among hydrological experts that households may run out of water before 2050. Temperature extremes in London range from 40.2 °C (104.4 °F) at Heathrow on 19 July 2022 down to −17.4 °C (0.7 °F) at Northolt on 13 December 1981. Records for atmospheric pressure have been kept at London since 1692. The highest pressure ever reported

8103-401: The effects of modifying the estuarine circulation. Fjord -type estuaries are formed in deeply eroded valleys formed by glaciers . These U-shaped estuaries typically have steep sides, rock bottoms, and underwater sills contoured by glacial movement. The estuary is shallowest at its mouth, where terminal glacial moraines or rock bars form sills that restrict water flow. In the upper reaches of

8214-601: The estuary impacted by human activities, and over time may shift the basic composition of the ecosystem, and the reversible or irreversible changes in the abiotic and biotic parts of the systems from the bottom up. For example, Chinese and Russian industrial pollution, such as phenols and heavy metals, has devastated fish stocks in the Amur River and damaged its estuary soil. Estuaries tend to be naturally eutrophic because land runoff discharges nutrients into estuaries. With human activities, land run-off also now includes

8325-424: The estuary, the depth can exceed 300 m (1,000 ft). The width-to-depth ratio is generally small. In estuaries with very shallow sills, tidal oscillations only affect the water down to the depth of the sill, and the waters deeper than that may remain stagnant for a very long time, so there is only an occasional exchange of the deep water of the estuary with the ocean. If the sill depth is deep, water circulation

8436-776: The estuary, with only narrow inlets allowing contact with the ocean waters. Bar-built estuaries typically develop on gently sloping plains located along tectonically stable edges of continents and marginal sea coasts. They are extensive along the Atlantic and Gulf coasts of the U.S. in areas with active coastal deposition of sediments and where tidal ranges are less than 4 m (13 ft). The barrier beaches that enclose bar-built estuaries have been developed in several ways: Fjords were formed where Pleistocene glaciers deepened and widened existing river valleys so that they become U-shaped in cross-sections. At their mouths there are typically rocks, bars or sills of glacial deposits , which have

8547-609: The first Muslim mayor of a major Western capital. The mayor's statutory planning strategy is published as the London Plan , which was most recently revised in 2011. The local authorities are the councils of the 32 London boroughs and the City of London Corporation . They are responsible for most local services, such as local planning, schools, libraries, leisure and recreation, social services , local roads and refuse collection. Certain functions, such as waste management , are provided through joint arrangements. In 2009–2010

8658-609: The fish community is dominated by hardy marine residents, and in summer a variety of marine and anadromous fishes move into and out of estuaries, capitalizing on their high productivity. Estuaries provide a critical habitat to a variety of species that rely on estuaries for life-cycle completion. Pacific Herring ( Clupea pallasii ) are known to lay their eggs in estuaries and bays, surfperch give birth in estuaries, juvenile flatfish and rockfish migrate to estuaries to rear, and anadromous salmonids and lampreys use estuaries as migration corridors. Also, migratory bird populations, such as

8769-498: The flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are typically classified according to their geomorphological features or to water-circulation patterns. They can have many different names, such as bays , harbors , lagoons , inlets , or sounds , although some of these water bodies do not strictly meet the above definition of an estuary and could be fully saline. Many estuaries suffer degeneration from

8880-400: The great biodiversity of this ecosystem. During an algal bloom , fishermen have noticed a significant increase in the quantity of fish. A sudden increase in primary productivity causes spikes in fish populations which leads to more oxygen being utilized. It is the continued deoxygenation of the water that then causes a decline in fish populations. These effects can begin in estuaries and have

8991-420: The impacts do not end there. Plant death alters the entire food web structure which can result in the death of animals within the afflicted biome . Estuaries are hotspots for biodiversity , containing a majority of commercial fish catch, making the impacts of eutrophication that much greater within estuaries. Some specific estuarine animals feel the effects of eutrophication more strongly than others. One example

9102-640: The location of its original headquarters in a road called Great Scotland Yard in Whitehall. The City of London has its own police force – the City of London Police . First worn by Met police officers in 1863, the custodian helmet has been called a "cultural icon" and a "symbol of British law enforcement". Introduced by the Met in 1929, the blue police telephone box (basis for the TARDIS in Doctor Who )

9213-525: The many chemicals used as fertilizers in agriculture as well as waste from livestock and humans. Excess oxygen-depleting chemicals in the water can lead to hypoxia and the creation of dead zones . This can result in reductions in water quality, fish, and other animal populations. Overfishing also occurs. Chesapeake Bay once had a flourishing oyster population that has been almost wiped out by overfishing. Oysters filter these pollutants, and either eat them or shape them into small packets that are deposited on

9324-422: The marine environment, such as plastics , pesticides , furans , dioxins , phenols and heavy metals . Such toxins can accumulate in the tissues of many species of aquatic life in a process called bioaccumulation . They also accumulate in benthic environments, such as estuaries and bay muds : a geological record of human activities of the last century. The elemental composition of biofilm reflect areas of

9435-575: The marsh causing increased rates of erosion . A similar phenomenon occurs in mangrove swamps , which are another potential ecosystem in estuaries. An increase in nitrogen causes an increase in shoot growth and a decrease in root growth. Weaker root systems cause a mangrove tree to be less resilient in seasons of drought, which can lead to the death of the mangrove. This shift in above ground and below ground biomass caused by eutrophication could hindered plant success in these ecosystems. Across all biomes, eutrophication often results in plant death but

9546-458: The mayor's budget proposals each year. The GLA has responsibility for the majority of London's transport system through its functional arm Transport for London (TfL), it is responsible for overseeing the city's police and fire services, and also for setting a strategic vision for London on a range of issues. The headquarters of the GLA is City Hall , Newham. The mayor since 2016 has been Sadiq Khan ,

9657-753: The most museums , art galleries, libraries, and cultural venues in the UK, including the British Museum , National Gallery , Natural History Museum , Tate Modern , British Library , and numerous West End theatres. Important sporting events held in London include the FA Cup Final , the Wimbledon Tennis Championships , and the London Marathon . It became the first city to host three Summer Olympic Games upon hosting

9768-675: The most diverse cities in the world. In 1951, the Festival of Britain was held on the South Bank . The Great Smog of 1952 led to the Clean Air Act 1956 , which ended the " pea soup fogs " for which London had been notorious, and had earned it the nickname the "Big Smoke". Starting mainly in the mid-1960s, London became a centre for worldwide youth culture , exemplified by the Swinging London sub-culture associated with

9879-440: The now off-balance nitrogen cycle , estuaries can be driven to phosphorus limitation instead of nitrogen limitation. Estuaries can be severely impacted by an unbalanced phosphorus cycle, as phosphorus interacts with nitrogen and silica availability. With an abundance of nutrients in the ecosystem, plants and algae overgrow and eventually decompose, which produce a significant amount of carbon dioxide. While releasing CO 2 into

9990-467: The old Roman city. By about 680 the city had become a major port again, but there is little evidence of large-scale production. From the 820s repeated Viking assaults brought decline. Three are recorded; those in 851 and 886 succeeded, while the last, in 994, was rebuffed. The Vikings applied Danelaw over much of eastern and northern England, its boundary running roughly from London to Chester as an area of political and geographical control imposed by

10101-614: The postcode area. SE1P is a non-geographic postcode district for PO boxes located in SE1. The approximate coverage of the postcode districts, with the historic postal district names shown in italics : SE1 has a very long tidal Thames frontage and is in Central London as is SE11, named after Kennington, close to Westminster . SE2–SE18 are spread across the north and east of the postcode area; enquiring into their naming system explains how SE2, SE7, SE8, SE10, SE16 and SE18 also front

10212-490: The principal city of the Roman province of Britannia in 100. At its height in the 2nd century, Roman London had a population of about 60,000. With the early 5th-century collapse of Roman rule, the walled city of Londinium was effectively abandoned, although Roman civilisation continued around St Martin-in-the-Fields until about 450. From about 500, an Anglo-Saxon settlement known as Lundenwic developed slightly west of

10323-466: The resources, and it was rapidly developing the dignity and the political self-consciousness appropriate to a national capital ." After winning the Battle of Hastings , William, Duke of Normandy was crowned King of England in newly completed Westminster Abbey on Christmas Day 1066. William built the Tower of London , the first of many such in England rebuilt in stone in the south-eastern corner of

10434-641: The rest of Britain, with Lyons , who opened the first of their chain of teashops in Piccadilly in 1894, leading the way. The tearooms, such as the Criterion in Piccadilly, became a popular meeting place for women from the suffrage movement. The city was the target of many attacks during the suffragette bombing and arson campaign , between 1912 and 1914, which saw historic landmarks such as Westminster Abbey and St Paul's Cathedral bombed. London

10545-467: The river. Postcode districts SE19–SE27 form a group in the southwest. The later addition, SE28, is in the northeast corner of the first group. The postcode area maps roughly to the combined area of the London Borough of Southwark , London Borough of Lewisham and Royal Borough of Greenwich . the eastern part of the London Borough of Lambeth , the northern part of the London Borough of Croydon ,

10656-460: The royal treasury came to rest in the Tower . While the City of Westminster developed into a true governmental capital, its distinct neighbour, the City of London , remained England's largest city and principal commercial centre and flourished under its own unique administration, the Corporation of London . In 1100, its population was some 18,000; by 1300 it had grown to nearly 100,000. With

10767-546: The sea. London is the seat of the Government of the United Kingdom . Many government departments, as well as the prime minister's residence at 10 Downing Street , are based close to the Palace of Westminster , particularly along Whitehall . There are 75 members of Parliament (MPs) from London; As of June 2024 , 59 are from the Labour Party , 9 are Conservatives , 6 are Liberal Democrats and one constituency

10878-427: The seawater in a layer that gradually thins as it moves seaward. The denser seawater moves landward along the bottom of the estuary, forming a wedge-shaped layer that is thinner as it approaches land. As a velocity difference develops between the two layers, shear forces generate internal waves at the interface, mixing the seawater upward with the freshwater. An examples of a salt wedge estuary is Mississippi River and

10989-411: The sediment which has a very high oxygen demand. This reduces the levels of oxygen within the sediment often resulting in partially anoxic conditions, which can be further exacerbated by limited water flow. Phytoplankton are key primary producers in estuaries. They move with the water bodies and can be flushed in and out with the tides . Their productivity is largely dependent upon the turbidity of

11100-424: The start of 2018 to mid April 2018. Funding cuts to police in London are likely to have contributed to this, though other factors are involved. However, homicide figures fell in 2022 with 109 recorded for the year, and the murder rate in London is much lower than other major cities around the world. London, also known as Greater London , is one of nine regions of England and the top subdivision covering most of

11211-753: The theatres in the 1640s. The ban on theatre was lifted during the Restoration in 1660, and London's oldest operating theatre, Drury Lane , opened in 1663 in what is now the West End theatre district. By the end of the Tudor period in 1603, London was still compact. There was an assassination attempt on James I in Westminster, in the Gunpowder Plot of 5 November 1605. In 1637, the government of Charles I attempted to reform administration in

11322-715: The unique governmental status of the City . In the English Civil War , the majority of Londoners supported the Parliamentary cause. After an initial advance by the Royalists in 1642, culminating in the battles of Brentford and Turnham Green , London was surrounded by a defensive perimeter wall known as the Lines of Communication . The lines were built by up to 20,000 people, and were completed in under two months. The fortifications failed their only test when

11433-456: The volume of freshwater, the tidal range, and the extent of evaporation of the water in the estuary. Drowned river valleys are also known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley. This is the most common type of estuary in temperate climates. Well-studied estuaries include

11544-453: The water and atmosphere, these organisms are also intaking all or nearly all of the available oxygen creating a hypoxic environment and unbalanced oxygen cycle . The excess carbon in the form of CO 2 can lead to low pH levels and ocean acidification , which is more harmful for vulnerable coastal regions like estuaries. Eutrophication has been seen to negatively impact many plant communities in estuarine ecosystems . Salt marshes are

11655-835: The water. The main phytoplankton present are diatoms and dinoflagellates which are abundant in the sediment. A primary source of food for many organisms on estuaries, including bacteria , is detritus from the settlement of the sedimentation. Of the thirty-two largest cities in the world in the early 1990s, twenty-two were located on estuaries. As ecosystems, estuaries are under threat from human activities such as pollution and overfishing . They are also threatened by sewage, coastal settlement, land clearance and much more. Estuaries are affected by events far upstream, and concentrate materials such as pollutants and sediments. Land run-off and industrial, agricultural, and domestic waste enter rivers and are discharged into estuaries. Contaminants can be introduced which do not disintegrate rapidly in

11766-568: The western part of the London Borough of Bexley and the northwestern part of the London Borough of Bromley are within the postcode area. In 2002, some residents in West Heath , a slight projection with neighbouring areas, wished to have their postcodes changed from SE2 to the adjacent DA7 postcode district, citing higher insurance for their houses, belongings and cars as reasons to change. Royal Mail has said it will not consider changes to postcodes for these reasons. London London

11877-639: The world's three most influential global cities . In January 2015, Greater London's population was estimated to be 8.63 million, its highest since 1939. During the Brexit referendum in 2016, the UK as a whole decided to leave the European Union , but most London constituencies voted for remaining. However, Britain's exit from the EU in early 2020 only marginally weakened London's position as an international financial centre. The administration of London

11988-1078: Was bombed by the Germans in the First World War , and during the Second World War , the Blitz and other bombings by the German Luftwaffe killed over 30,000 Londoners, destroying large tracts of housing and other buildings across the city. The tomb of the Unknown Warrior , an unidentified member of the British armed forces killed during the First World War, was buried in Westminster Abbey on 11 November 1920. The Cenotaph , located in Whitehall ,

12099-437: Was once a common sight throughout London and regional cities in the UK. The British Transport Police are responsible for police services on National Rail , London Underground , Docklands Light Railway and Tramlink services. The Ministry of Defence Police is a special police force in London, which does not generally become involved with policing the general public. The UK's domestic counter-intelligence service ( MI5 )

12210-465: Was supervised by polymath Robert Hooke . In 1710, Christopher Wren 's masterpiece, St Paul's Cathedral , was completed, replacing its medieval predecessor that burned in the Great Fire of 1666. The dome of St Paul's dominated the London skyline for centuries, inspiring the artworks and writing of William Blake , with his 1789 poem " Holy Thursday " referring to 'the high dome of Pauls'. During

12321-524: Was unveiled on the same day, and is the focal point for the National Service of Remembrance held annually on Remembrance Sunday , the closest Sunday to 11 November. The 1948 Summer Olympics were held at the original Wembley Stadium , while London was still recovering from the war. From the 1940s, London became home to many immigrants, primarily from Commonwealth countries such as Jamaica, India, Bangladesh and Pakistan, making London one of

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