North Sea
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{{Infobox Ocean
| Ocean_name = North Sea
| image_Ocean = NASA NorthSea1.jpg
| caption_Ocean =
| image_bathymetry =
| caption_bathymetry=
| location = [[Atlantic Ocean]]
| coords = {{coord|56|N|03|E|scale:4000000_type:waterbody|display=inline}}
| type =
| inflow = [[River Forth|Forth]], [[Ythan Estuary|Ythan]], [[Elbe]], [[Weser]], [[Ems (river)|Ems]], [[Rhine]]/[[Waal (river)|Waal]], [[Meuse River|Meuse]], [[Scheldt]], [[River Spey|Spey]], [[River Tay|Tay]], [[Thames]], [[Humber]], [[River Tees|Tees]], [[River Wear|Wear]], [[River Tyne|Tyne]]
| outflow =
| catchment =
| basin_countries = [[Norway]], [[Denmark]], [[Germany]], [[Netherlands]], [[Belgium]], [[France]] and the [[United Kingdom|U.K.]] ([[England]], [[Scotland]])
| length = 600 mi (970 km)<ref Name="Stats1">{{Citation
| last =Royal Belgian Institute of Natural Sciences
| first =
| author-link =
| last2 =
| first2 =
| author2-link =
| title =MUMM North Sea facts
| date =
| year =2002-2007
| url =http://www.mumm.ac.be/EN/NorthSea/facts.php
| accessdate = 2007-07-19}}</ref>
| width = 350 mi (560 km)
| area = 222,000 mi² (575,000 km²)<ref name="Stats"/>
| depth = 308 ft (94 m)<ref Name="Statistics">{{Citation
| last =OSPAR Commission, for the protection of the marine environment of the North-East Atlantic.
| first =
| author-link =
| last2 =
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| author2-link =
| title =Geography, hydrography and climate
| date =
| year =2007
| url =http://www.ospar.org/eng/doc/pdfs
| accessdate = 2007-07-19}}</ref>
| max-depth = c.2,165 ft/660 m<ref Name="Stats">{{Citation
| last =Answers Corporation
| first =
| author-link =
| last2 =
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| author2-link =
| title =North Sea: Definition and Much More from Answers.com
| date =
| year =2007
| url =http://www.answers.com/topic/north-sea?cat=travel
| accessdate = 2007-07-19}}</ref>
| volume = 94 000 km
| residence_time =
| salinity =
| temperature_high =
| temperature_low =
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The '''North Sea''' is a [[marginal sea|marginal]], [[epeiric sea]] of the [[Atlantic Ocean]] on the European [[continental shelf]]. It is more than {{convert|600|mi|km}} long and {{convert|350|mi|km}} wide, with an area of around {{convert|222000|sqmi|km2}}. A large part of the European [[drainage basin]] empties into the North Sea including water from the [[Baltic Sea]]. The North Sea connects with the rest of the Atlantic through the [[Dover Strait]] and the [[English Channel]] in the south and through the [[Norwegian Sea]] in the north.
The North Sea averages about 100 m (325 ft) deep, with a maximum depth of 700 m (2300 ft) and in some areas shallows can be a mere 15 m deep. The North Sea lies above what used to be the triple junction between three continental tectonic plates in the early [[Paleozoic]] Era. Movement on the [[fault]]s associated with these tectonic phenomena can still cause [[earthquake]]s and small [[tsunami]]s. The sea's coastal features are the result of [[glacier|glacial]] movements rather than [[tectonics]]. Deep [[fjord]]s and sheer cliffs mark the coastline of the northern part of the North Sea, whereas the southern coasts consist of sandy beaches and [[mudflat]]s. These flatter areas are particularly susceptible to flooding, especially as a result of [[storm tide]]s. Elaborate systems of [[Dike (construction)|dikes]] have been constructed to protect coastal areas.
The development of European civilization has been heavily affected by the maritime traffic on the North Sea. The [[Roman Empire|Romans]] and the [[Viking]]s sought to extend their territory across the sea. Both the [[Hanseatic League]] and the [[Netherlands]] sought to dominate commerce on the North Sea and through it to access the markets of the world. Britain's development as a sea power depended heavily upon its dominance in the North Sea, where some of its rivals sought power, first the Netherlands and finally Germany and to a lesser extent Russia and the Scandinavian nations. Commercial enterprises, growing populations, and limited resources gave the nations on the North Sea the desire to control or access the North Sea for their own commercial, military, and colonial ends.
Its importance has turned from the military to the economic. Traditional economic activities, such as fishing and shipping, have continued to grow and other resources, such as fossil fuels and wind energy, have been discovered and developed.
==Naming==
The name of the North Sea originates from its relationship to the land of the [[Frisia]]ns. Frisia lies directly to the south of the ''North Sea'', to the west of the ''[[Baltic Sea|East Sea]]'' (''Oostzee'', the Baltic Sea), to the north of the former ''[[Zuiderzee|South Sea]]'' (''Zuiderzee'', today's [[IJsselmeer]]) and the today-[[Land reclamation|reclaimed]] ''[[Middelzee|Middle Sea]]'' (''Middelzee''). The name “North Sea” is attested in Middle High German and probably harks back to the name given by the Frisians, who settled on its south coast. Even the early Spanish name was ''Mar del Norte''.<ref>{{Citation
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| title =Common-place: Naming the Pacific
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| url =http://www.common-place.org/vol-05/no-02/peterson/index.shtml
| accessdate = 2007-07-19}}</ref>
From the point of view of the German [[Hanseatic League|Hanseatic towns]] of the [[Middle Ages]], the sea to the east was the “East Sea” (Baltic Sea in German is literally the ''Ostsee''), and the sea to the north, the North Sea. The spread of maps used by Hanseatic merchants popularized this name throughout Europe. Other common names in use for long periods were ''Mare Frisia'', and ''Mare Frisicum'', ''Oceanum-'' or ''Mare Germanicum'' as well as their English equivalents, Frisian Sea and German Ocean or Sea.
"German Sea" or "Germanic Sea"<ref> "The North Sea was known as the German Ocean until the early 20th C., when hostilities with Germany meant this name became politically unacceptable in Great Britain." [http://www.geo.ed.ac.uk/scotgaz/features/featurefirst7877.html]</ref> (from the Latin ''[[wikt:en:Mare Germanicum|Mare Germanicum]]'') was commonly used in [[English language|English]] and other languages along with "North Sea", until the early eighteenth century. By the late nineteenth century, both "German-" and "Germanic Sea" were rare, scholarly usages.
==History==
{{main|History of the North Sea}}
===Early history===
The first records of marine traffic on the North Sea come from the [[Roman Empire]], which began exploring the sea in 12 BC. Great Britain was formally invaded in 43 AD and its southern areas incorporated into the Empire, beginning sustained trade across the North Sea and the English Channel. The Romans abandoned Britain in 410 and in the power vacuum they left, the Germanic [[Angles]], [[Saxons]], and [[Jutes]] began the next great migration across the North Sea during the [[Migration Period]], conquering and displacing the native [[Celt]]ic populations.<ref>{{Citation
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| title =Germany The migration period
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| url =http://www.britannica.com/eb/article-58084/Germany
| accessdate = 2007-07-24}}</ref>
[[Image:Viking Expansion.svg|thumb|right|250px|Viking expansion and raiding by century]]
The [[Viking Age]] began in 793 with the attack on [[Lindisfarne]] and for the next quarter-millennium the Vikings ruled the North Sea. In their superior [[longships]], they raided, traded, and established colonies and outposts on the Sea's coasts.
As Viking dominance waned, trade on the North Sea came to be controlled by the [[Hanseatic League]]. The League, though centred on the [[Baltic Sea]], had important outposts on the North Sea. Goods from all over the world flowed through the North Sea on their way to and from the Hanseatic cities.
By 1441, the Netherlands had risen as an economic and shipping power to rival the League. By the 16th Century, the Netherlands were the leading economic power. The North Sea was a hotbed of commerce and shipping connecting far-flung colonies with markets all over Europe.
===Early modern history===
[[Image:Willem van de Velde (II) - De verovering van het Engelse admiraalschip de 'Royal Prince'.jpg|thumb|200px|Painting of the [[Four Days Battle]] of 1666 by Willem van de Velde]]
Dutch power during her [[Dutch Golden Age|Golden Age]] was a concern for growing England, which saw its future in the merchant marine and overseas colonies. This conflict was at the root of the first three [[Anglo-Dutch Wars]] between 1652 and 1673. By the end of the [[War of Spanish Succession]] in 1714, the Dutch were no longer a major player in European politics.
Britain's naval supremacy faced its only real challenge before the 20th Century from [[Napoleonic France]] and her continental allies. In 1800, a union of lesser naval powers, called the [[League of Armed Neutrality]], formed to protect neutral trade during Britain's conflict with France. The British Navy defeated the combined forces of the [[League of Armed Neutrality]] in the [[Battle of Copenhagen]] in 1801 in the Kattegat. Britain later defeated the French Navy in the [[Battle of Trafalgar]] off the coast of [[Spain]].
===20th Century===
[[Image:Bluecher sinkend.jpg|right|thumb|200px|The German Cruiser [[SMS Blücher]] sinks in the Battle of Dogger Bank on 25 January 1915. ]]
Tensions in the North Sea were again heightened in 1904 by the [[Dogger Bank incident]], in which Russian naval vessels mistook British fishing boats for Japanese ships and fired on them, and then upon each other. The incident, combined with Britain's [[Anglo-Japanese Alliance|alliance with Japan]] and the [[Russo-Japanese War]] led to an intense diplomatic crisis. The crisis was defused when Russia was defeated by the Japanese and agreed to pay compensation to the fishermen.
During the [[First World War]], Great Britain's [[Grand Fleet]] and Germany's [[Kaiserliche Marine]] faced each other on the North Sea, which became the main [[Naval warfare of World War I#Theaters|theatre of the war]] for surface action. Britain's larger fleet was able to establish an effective blockade for most of the war that restricted the [[Central Powers]]' access to many crucial resources. Major battles included the [[Battle of Heligoland Bight]], the [[Battle of Dogger Bank (1915)|Battle of the Dogger Bank]], the [[Battle of Jutland]], and the [[Second Battle of Heligoland Bight]]. Britain, though not always tactically successful, maintained the blockade and thus kept the [[High Seas Fleet]] in port. Conversely, the German navy remained a threat that kept the vast majority of Britain's [[capital ships]] in the North Sea.
The [[Second World War]] also saw action in the North Sea, though it was restricted more to submarines and smaller vessels such as [[Minesweeper (ship)|minesweepers]], and [[Fast Attack Craft]].<ref>{{Citation
| last = Campaigns of World War II
| first = Naval History Homepage
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| title =Atlantic, WW2, U-boats, convoys, OA, OB, SL, HX, HG, Halifax, RCN ... | date =
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| url =http://www.naval-history.net/WW2CampaignsStartEurope.htm
| accessdate = 2007-07-24}}</ref>
On [[April 9]], [[1940]], the Germans initiated [[Operation Weserübung]] in which almost the entire German fleet was focused north toward Scandinavia in the North Sea as well as in the Skagerrak and Kattegat.<ref>{{Citation
| last = LemaireSoft
| first =
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| last2 =
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| title =LemaireSoft's Naval Encyclopedia of World War 2: Hipper
| date =
| year =November 18, 2005
| url =http://www.lemaire.happyhost.org/ship/edito/1950.html
| accessdate = 2007-07-24
| format ={{dead link|date=June 2008}} – <sup>[http://scholar.google.co.uk/scholar?hl=en&lr=&q=author%3ALemaireSoft+intitle%3ALemaireSoft%27s+Naval+Encyclopedia+of+World+War+2%3A+Hipper&as_publication=&as_ylo=November 18, 2005&as_yhi=November 18, 2005&btnG=Search Scholar search]</sup>}}</ref> Throughout the German occupation of Norway, the [[Shetland Bus]] operation ran secretly across the North Sea from Great Britain to Norway. First, Norwegian fishing boats were used, and then three {{ft to m|num=100|abbr=no|spell=Commonwealth|precision=2|wiki=yes}} [[submarine chaser]]s. (see also: [[HNoMS Hitra|HNoMS ''Hitra'']]).<ref>{{cite web|url=http://www.shetland-heritage.co.uk/shetlandbus/pages/the_operation.htm|title=www.shetland-heritage.co.uk/shetlandbus/pages/the_operation.htm<!--INSERT TITLE-->}}</ref>
In the last years of the war and the first years thereafter, huge volumes of weapons were disposed-of by being sunk in the North Sea. These comprised mainly [[grenades]], [[land mines]], [[naval mines]], [[bazookas]], [[Cartridge (firearms)|cartridges]], and some [[chemical weapons]]. Though estimates vary widely, hundreds of thousand tons of munitions were sunk.<ref>{{Citation
| last = Koch
| first = Marc
| author-link =
| last2 = Ruck
| first2 = Wolfgang
| author2-link =
| title = Securing and Remediation Concepts for Dumped Chemical and Conventional Munitions in the Baltic Sea
| date =
| year =
| url =http://www.dstl.gov.uk/conferences/cwd/2006/034.pdf
| accessdate = 2007-10-26}}</ref>
After the war, the North Sea lost much of its military significance because it is bordered only by [[NATO]] member-states. The North Sea gained significant economic meaning in the 1960s as the states on the North Sea began to exploit its oil and gas resources.
===Political status===
[[Image:north sea eez.PNG|right|thumb|200px|The [[Exclusive Economic Zone]]s in the North Sea]]
The countries bordering the North Sea all claim the twelve [[nautical miles]] of [[territorial waters]] within which they have exclusive fishing rights. [[Iceland]], however, as a result of the [[Cod Wars]] has exclusive fishing rights for 200 mi (320 km) from its coast, into parts of the North Sea. The [[Common Fisheries Policy]] of the [[EU]] exists to coordinate fishing rights and assist with disputes between EU states and the EU border state of Norway.
After the discovery of mineral resources in the North Sea, Norway claimed its rights under the [[Continental Shelf Convention]]. The other countries on the sea followed suit. These rights are largely divided along the median line. The median line is defined as the line "every point of which is equidistant from the nearest points of the baselines from which the breadth of the territorial sea of each State is measured."<ref>{{Citation
| last =The Multilaterals Project, The Fletcher School, Tufts University
| first =
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| title = Convention on the Continental Shelf, Geneva.
| date =29 April 1958
| year =
| url =http://fletcher.tufts.edu/multi/texts/BH366.txt
| accessdate = 2007-07-24}}</ref>
The ocean floor border between Germany, the Netherlands, and Denmark was only reapportioned after protracted negotiations and a judgment of the [[International Court of Justice]].<ref>{{Citation
| last =International Court of Justice
| first =
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| title = North Sea Continental Shelf Cases
| date =Judgment of 20 February 1969
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| url =http://www.u-paris2.fr/cij/icjwww/idecisions/isummaries/icssummary690220.htm
| accessdate = 2007-07-24
| format = {{dead link|date=June 2008}} – <sup>[http://scholar.google.co.uk/scholar?hl=en&lr=&q=author%3AInternational+Court+of+Justice+intitle%3ANorth+Sea+Continental+Shelf+Cases&as_publication=&as_ylo=&as_yhi=&btnG=Search Scholar search]</sup>}}</ref>
Environmental concerns led to the [[MARPOL 73/78]] Accords, which created {{convert|25|mi|km|abbr=on}} and 50 mi (40 and 80 km) zones of protection. The [[Convention for the Protection of the Marine Environment of the North-East Atlantic]] is established for the preservation of the ocean in the region. Germany, Denmark, and the Netherlands have a trilateral agreement for the protection of the [[Wadden Sea]], or [[mudflat]]s, which run along the coasts of the three countries on the southern edge of the North Sea.
==Geography==
[[Image:Nseamap.gif|right|thumb|200px|The North Sea]]
For the most part, the sea lies on the European [[continental shelf]]. The only exception is a narrow area of the northern North Sea off [[Norway]]. The North Sea is bounded by [[Great Britain]] to the west and the northern and central European mainland to the east and south, including Norway, [[Denmark]], [[Germany]], the [[Netherlands]], [[Belgium]], and [[France]].
In the south-west, the North Sea becomes the [[English Channel]] beyond the [[Straits of Dover]]. In the east, it connects to the [[Baltic Sea]] via the [[Skagerrak]] and [[Kattegat]]. In the north, it opens in a widening funnel shape to the [[Norwegian Sea]], which lies in the very north-eastern part of the [[Atlantic]].
Apart from the obvious boundaries formed by the coasts of the countries which border it, the North Sea is generally considered to be bounded by an imaginary line from [[Lindesnes]], Norway to [[Hanstholm]], Denmark running towards the Skagerrak. However, for statistical purposes, the Skagerrak and the Kattegat are sometimes included as part of the North Sea.<ref>{{cite web|url=http://saup.fisheries.ubc.ca/lme/SummaryInfo.aspx?LME=22|title=Fisheries Centre of the University of British Columbia}}</ref> The northern limit is less well-defined. Traditionally, an imaginary line is taken to run from northern [[Scotland]], by way of [[Shetland]], to [[Ålesund]] in Norway. According to the [[Convention for the Protection of the Marine Environment of the North-East Atlantic]]<ref>{{Citation
| last = OSPAR Commission
| first =
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| last2 =
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| title =OSPAR / The OSPAR Convention
| date =2004 -
| year =
| url =http://www.ospar.org/eng/html/1992-ospar-convention.htm
| accessdate =2007-07-24 }}</ref>of 1962 it runs further to the west and north from longitude 5° West and latitude 62° North, at the latitude of [[Geirangerfjord]] in Norway.
The surface area of the North Sea is approx. 575,000 [[square kilometre]]s (222,000 sq mi)<ref name="Statistics"/> with a volume of around 54,000 [[cubic metre|cubic kilometres]] (13,000 cu mi).<ref name="Stats"/> This places the North Sea at the 13th largest sea on the planet.<ref name="Statistics1">{{Citation
| last =Royal Belgian Institute of Natural Sciences
| first =
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| author2-link =
| title =MUMM North Sea facts
| date =
| year =2002-2007
| url =http://www.mumm.ac.be/EN/NorthSea/facts.php
| accessdate = 2007-07-19 }}</ref>
==Geology==
===Geological history===
[[Image:2004 07 31-L51 ubt.jpeg|right|thumb|200px|North Sea cliff]]
The [[Seabed|bed]] of the North Sea forms two [[Sedimentary basin|basins]]. The main northern one lies to the north of a [[ridge]] between [[Norfolk]] and [[Frisia]], and had its origin in the [[Devonian]]. The southern basin, if not flooded, would drain towards the [[Strait of Dover]] and thence to the [[English Channel]]. This basin dates from the [[Carboniferous]].<ref>{{cite web|url=http://jgs.geoscienceworld.org/cgi/content/abstract/131/5/435|title=Review of North Sea Basin development}}</ref>
During the most recent glaciation, the [[Devensian glacial|Devensian]] much of the northern basin was covered by the [[ice sheet]], and the remainder, including the southern basin, was [[tundra]]. However, during the [[Cromerian interglacial]], there was a natural dam of [[chalk]], the [[Weald-Artois Anticline]]."<ref>{{Citation
| last =Invicta Media
| first =
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| last2 =
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| author2-link =
| title =Forming the Channel
| date =30 March 2002;
| year =1999-2002
| url =http://www.theotherside.co.uk/tm-heritage/background/channelform.htm
| accessdate = 2007-07-25 }}</ref> Although the ridge probably collapsed during the [[Kansan glaciation]] it still formed the highest part of the land bridge between continental Europe and Great Britain.<ref>{{cite news |first=Ian |last=Sample |authorlink= |coauthors= |title=Breach of ice age lake made Britain an island |url=http://www.guardian.co.uk/science/story/0,,2129662,00.html |work=The Guardian |publisher= |date= 19 July 2007|accessdate=2007-07-21 }}</ref>
The [[Storegga Slide]]s were a series of underwater landslides, in which a piece of the Norwegian continental shelf slid into the Norwegian Sea. The immense landslips occurred between 8150 BC and 6000 BC, and caused a tsunami up to 20 m (65 ft) high that swept through the North Sea, having the greatest effect on Scotland and the Faeroe Islands.<ref name=spiegel>{{Cite web
| author= Axel Bojanowski,
| publisher= Spiegel Online
| title =Tidal Waves in Europe? Study Sees North Sea Tsunami Risk
| date = October 11, 2006
| year =
| url =http://www.spiegel.de/international/0,1518,441819,00.html
| accessdate = 2007-07-24}}</ref><ref>{{cite journal | first = Stein | last = Bondevik | coauthors = Dawson, Sue; Dawson, Alastair; Lohne, Øystein | year = 2003 | month = [[5 August]] | title = Record-breaking Height for 8000-Year-Old Tsunami in the North Atlantic | journal = EOS, Transactions of the American Geophysical Union | volume = 84 | issue = 31 | pages = 289, 293| url = http://www.ibg.uit.no/~stein/Bondevik-al-03-EOS.pdf | accessdate = 2007-01-15}}</ref>
===Plate tectonics===
[[Image:Euramerica en.svg|thumb|right|200px|The North Sea lies over the triple suture of what used to be three separate continents in the Paleozoic]]
The North Sea lies above what used to be the [[triple junction]] between three continental tectonic plates in the early [[Paleozoic]] Era. Later, in the [[Mesozoic]] Era, a North-South trending [[rift valley]] or [[graben]] formed down the middle of the North Sea. Fault lines along the [[English Channel]] cause occasional earthquakes, which can result in damage to structures on land. The axial grabens of the North Sea also form a tectonically active area. Northwestern Europe's continental slope is subject to [[landslide]]s from [[earthquake]]s.<ref>{{Citation
| last = Geology Shop
| title =UK Earthquakes
| date =
| year =
| url =http://www.geologyshop.co.uk/ukequakes.htm
| accessdate = 2007-07-24}}</ref>
Although not a site of major earthquakes or tsunamis, there are intraplate earthquakes which result in the uplifting of the continental crust<ref>{{cite journal
| last =Bott
| first = Martin H P
| authorlink = Martin Bott
| coauthors = Bott, Jacqueline D J
| title =Cenozoic uplift and earthquake belt of mainland Britain as a response to an underlying hot, low-density upper mantle (Abstract)
| journal =Journal of the Geological Society
| volume =
| issue =
| pages =
| date =Jan 2004
| url =http://findarticles.com/p/articles/mi_qa3721/is_200401/ai_n9378523
| doi =
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| accessdate = 2007-07-24 }}</ref>
causing landslides.<ref name=spiegel/> The [[Dover Straits earthquake of 1580]] is among the first recorded in the North Sea and caused extensive damage in both [[France]] and [[England]] both through its tremors and a [[tsunami]]. The largest earthquake ever recorded in the [[United Kingdom]] was the [[1931 Dogger Bank earthquake]], which measured 6.1 on the [[Richter Scale]] and caused a tsunami that flooded parts of the British coast.{{fact|date=July 2008}}
The North Sea is located at a triple junction of three continental plates formed during the [[Palaeozoic]]: [[Avalonia]], [[Laurentia]] and [[Baltica]].<ref>{{Cite journal
| last = Lyngsie, S B
| coauthors = Rasmussen, T M; Thybo, H
| journal = Tectonophysics
| volume = 413
| pages = 147–170
| title = Regional geological and tectonic structures of the North Sea area from potential field modelling
| date = October 11, 2006
| year = 2006
| url = http://www.lyngsie.nu/Artikel-1.pdf
| accessdate = 2007-07-24
| doi = 10.1016/j.tecto.2005.10.045}}</ref>
Baltica is now the eastern coastline and the [[Scandinavia]]n countries; Avalonia consists of the southern and western North Sea coast along England, northern [[Germany]] and France; and Laurentia marks the northern perimeter of the North Sea with the [[Atlantic Ocean]].
===Geological features===
[[Image:Doggerbank.jpg|thumb|right|200px| The Dogger Bank]]
The [[Norwegian trench]] reaches from the [[Stad (peninsula)|Stad]] peninsula in [[Sogn og Fjordane]] to the [[Oslofjord]]. The trench is between 50 and 95 km (30-60 mi) wide and hundreds of meters deep. Off the [[Rogaland]] coast, it is 250 - 300 m (820-980 ft) deep, and at its deepest point, off [[Arendal]], it reaches 700 m (2300 ft) deep as compared to the average depth of the North Sea, about 100 m (325 ft). The trench is not a [[subduction]]-related [[oceanic trench]]. It is mainly a deep [[erosion]]al scour, while the Western part follows the North-South line of an old [[Rift Valley]] formed during the [[Jurassic]] and [[Cretaceous]] periods, also known as the [[Viking Graben]].
To the East of Great Britain, the vast [[moraine|morainic]] plate of the [[Dogger Bank]] rises up to 15 to 30 m deep.<ref>{{Citation
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| title =Maptech : Topo Maps Charts Navigation Software GPS and Online MapServer
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| url =http://mapserver.maptech.com/homepage/index.cfm?lat=54.74456315454079&lon=2.3527509224287115&scale=1500000&zoom=50&type=0&icon=0&width=498&height=498&searchscope=dom&CFID=1719760&CFTOKEN=33728793&scriptfile=http://mapserver.maptech.com/homepage/index.cfm&latlontype=DMS
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The [[Silver Pit]] is a valley-like depression 45 km (27 mi) east of [[Spurn Head]] in England that has been recognized for hundreds of years by fishermen. Nearby is the [[Silverpit crater]], a controversial structure, which may be a geological structure or may be an [[impact crater]].
"The [[Long Forties]]" denotes an area of the northern North Sea that is fairly consistently forty [[fathom]]s (73 m) deep (thus, on a [[nautical chart]] with depth shown in fathoms, a long area with many "40" notations). It is located between the northeast coast of Scotland and the southwest coast of Norway, centred about 57°N 0°30′E.
The [[Broad Fourteens]] are an area of the southern North Sea that is fairly consistently fourteen fathoms (26 m) deep (thus a broad area with many "14" notations). It is located off the coast of the Netherlands and south of the Dogger Bank, roughly between longitude 3°E and 4°30′E and latitude 52°30′N and 53°30′N.
Around the edges of the North Sea are a number of [[List of the largest islands of the North Sea|sizable islands]] and [[archipelago]]s, including the [[Shetland]], [[Orkney]], and [[Frisian Islands|Frisian]] islands.
==Biology and the environment==
===Fish===
[[Copepod]]s and other [[zooplankton]] are plentiful in the North Sea. These tiny organisms are crucial elements of the [[food chain]] supporting many species of fish. The North Sea is home to about 230 species of fish. [[Cod]], [[haddock]], [[whiting]], [[saithe]], [[plaice]], [[sole]], [[mackerel]], [[herring]], [[pouting]], [[sprat]], and [[sandeel]] are all very common and the target of commercial fishing.<ref> {{Citation
| title = OSPAR Quality Status Report for the Greater North Sea
| work= OSPAR
| date =
| year = 2000
| url =http://www.bmu.de/files/pdfs/allgemein/application/pdf/kapitel5_ospar_report.pdf
| accessdate = 2007-12-21 }}</ref> Due to the various depths of the North Sea trenches and differences in salinity, temperature, and water movement some fish reside only in small areas of the North Sea. The blue-mouth redfish and [[rabbitfish]] are a few examples of these.<ref>{{Citation
| title =Factors affecting the distribution Of North Sea fish
| work=International council for the Exploration of the Sea ICES
| date =
| year =
| url =http://www.ices.dk/marineworld/fishmap/pdfs/factors.pdf
| accessdate = 2007-12-09 }}</ref>
[[Crustacean]]s are also commonly found throughout the sea. [[Norway lobster]], deep-water [[prawn]]s, and [[brown shrimp]] are all commercially fished, but other species of [[lobster]], [[shrimp]], [[oyster]], [[mussels]] and [[clams]] are all found.
===Birds===
The coasts of the North Sea are home to [[nature reserve]]s including the [[Ythan Estuary]], [[Fowlsheugh]] Nature Preserve, and [[Farne Islands]] in the UK and The [[Wadden Sea National Parks]] in Germany. These locations provide breeding [[Habitat (ecology)|habitat]] for dozens of bird species. Tens of millions of birds make use of the North Sea for breeding, feeding, or migratory stopovers every year. Populations of [[Northern fulmar]]s, [[Black-legged Kittiwake]]s, [[Atlantic puffin]]s, [[razorbill]]s, and a variety of species of [[petrel]]s, [[gannet]]s, [[seaduck]]s, [[loon]]s (divers), [[cormorant]]s, [[gull]]s, [[auk]]s, and [[tern]]s, and many other seabirds make these coasts popular for [[birdwatching]].<ref>
| title = OSPAR Quality Status Report for the Greater North Sea
| work= OSPAR
| date =
| year = 2000
| url =http://www.bmu.de/files/pdfs/allgemein/application/pdf/kapitel5_ospar_report.pdf
| accessdate = 2007-12-21</ref>
===Marine mammals===
The North Sea is also home to a variety of marine mammals. [[Common seal]]s, [[grey seal]]s can be found along the coasts and at marine installations and islands. The very northern North Sea islands like the Shetlands are occasionally home to a larger variety of [[pinnipeds]] including [[bearded seal|bearded]], [[harp seal|harp]], [[hooded seal|hooded]] and [[ringed seal]]s, and even [[walrus]].<ref>{{Citation
| title = Marine mammals in the waters of the north sea
| work= The North Sea Bird Club
| date =
| year =
| url = http://www.abdn.ac.uk/nsbc/mar_mammals.hti
| accessdate = 2007-12-21}}</ref> North Sea [[cetaceans]] include [[Harbour porpoise]]s, [[common dolphin]]s, [[bottlenose dolphin]]s, [[Risso's dolphin]]s, [[long-finned pilot whale]]s and [[white-beaked dolphin]]s, [[minke whale]]s, [[killer whale]]s, and [[sperm whales]]<ref> {{Citation
| title =Whales and dolphins in the North Sea 'on the increase'
| work= Newcaslte University Press Release
| date = 2 April
| year = 2005
| url = http://www.ncl.ac.uk/press.office/press.release/content.phtml?ref=1112607082
| accessdate = 2007-12-21 }}</ref>
===Environmental health===
Historically, [[flamingo]]s, [[pelican]]s, and [[Great Auk]] could be found along the southern shores of the North Sea<ref>{{cite web
| title = Following in the footsteps of the North Sea flamingo
| url=http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2006/11/03/ufish123.xml
| accessdate = 2008-01-04 }}
</ref>. Gray whale also resided in the North Sea but were driven to extinction in the Atlantic in the 1600s. Other species have seen dramatic declines in population, though they are still to be found; [[right whale]]s, [[sturgeon]], [[shad]], [[Batoidea|rays]], [[skate]]s and [[salmon]] among other species were common in the North Sea into the 20th Century, when numbers declined.
A variety of factors have contributed to decreasing populations of North Sea fauna. The introduction of [[non-indigenous species]], industrial and agricultural [[pollution]], [[overfishing]] and [[trawling]], [[dredging]], human-induced [[eutrophication]], construction on coastal breeding and feeding grounds, sand and gravel extraction, offshore construction, and heavy shipping traffic all threaten marine life in the North Sea.<ref>{{Citation
| title = OSPAR Quality Status Report for the Greater North Sea
| work= OSPAR
| date =
| year = 2000
| url =http://www.bmu.de/files/pdfs/allgemein/application/pdf/kapitel5_ospar_report.pdf
| accessdate = 2007-12-21 }}</ref>
In recent decades action has been taken by the border countries to address many of these threats. The [[OSPAR]] convention was created in 1992 as and expansion of the 1972 [[Oslo Convention]]. It is managed by the OSPAR commission and has taken action to counteract the harmful effects of human activity on wildlife in the North Sea and preserve many endangered species.
==Hydrology==
=== Basic data ===
The [[salinity]] of the water is dependent on place and time of year but is generally in the range of 15 to 25 [[parts-per notation|parts per thousand]] (ppt) around river mouths and up to 32 to 35 ppt in the northern North Sea,<ref Name="Statistics1"/> still generally lower than North Atlantic salinity, which averages around 35 ppt.
The water temperature varies depending on the influence of the Atlantic currents, water depth, and time of year, reaching 21 °C (77 °F) in summer and 6 °C (50 °F) in winter, though Arctic currents can be colder. The eastern side is both the warmest in summer and the coldest in winter. In the deeper northern North Sea, the water remains a nearly constant 10 °C (50 °F) year round because of water exchange with the Atlantic. The greatest temperature variations are found on the very shallow Wadden Sea coast, where ice can form in very cold winters.<ref Name="Statistics1"/>
The exchange of salt water between the North Sea and Atlantic occurs through the English Channel, as well as in the northern North Sea along the Scottish coast and through the Norwegian Sea. The North Sea receives [[fresh water]] not only from inflow of rivers but also from the low salinity Baltic Sea which drains into the North Sea via the Skagerrak. The North Sea rivers drain a land area of 841,500 km² (324,905 sq mi) and supply 296-354 km³ (71-85 cu mi) of fresh water annually. The Baltic rivers drain almost twice as large an area (1,650,000 km², 637,068 sq mi) and contribute 470 km³ (113 cu mi) of fresh water annually.<ref Name="Statistics1"/>
Around 185 million people live in the [[catchment area]] of the rivers that flow into the North Sea.<ref> {{Citation
| title = OSPAR Quality Status Report 2000
| work= OSPAR
| date =
| year = 2000
| url = http://www.ospar.org/eng/html/welcome.html
| accessdate = 2007-12-21 }}</ref> These rivers drain a large part of Western Europe: a quarter of France, three quarters of Germany, nearly all of Switzerland, half of [[Jutland]], the whole of the Netherlands and Belgium, the southern part of Norway, the Rhine basin of western Austria and the eastern side of Great Britain.<ref> {{Citation
| title = OSPAR Quality Status Report 2000
| work= OSPAR
| date =
| year = 2000
| url = http://www.ospar.org/eng/html/welcome.html
| accessdate = 2007-12-21 }}</ref> This area contains one of the world's greatest concentrations of industry.
===Water circulation===
The main pattern to the flow of water in the North Sea is a [[counter-clockwise]] rotation along the edges.<ref>[http://www.defra.gov.uk/environment/water/marine/uk/policy/cleanerseas/cs03.htm Department for the Environment, Food and Rural Affairs, UK: Marine: Cleaner Seas report]</ref> Water from the [[Gulf Stream]] flows in both through the English Channel towards Norway, and around the north of Britain, moving south along the British coast. From the south-moving current smaller currents are pulled off eastwards into the central North Sea. Another significant current sweeps south in the eastern part of the Sea. This is cold North Atlantic water and is strongest in late spring and early summer when the British offshore waters remain cool while the sea off the Netherlands and Germany starts warming up. Water from the Channel, and water flowing out of the Baltic Sea eventually move north along the Norwegian coast back into the Atlantic in what is called the [[Norwegian Current]].<ref name="SaS"/> The current moves at a depth of some 50 to 100 m (165-330 ft). It has a relatively low salinity due to the [[brackish water]] of the Baltic and the fresh water contributed by the rivers and the [[fjords]]. Though the current is, on average, cooler than the North Sea water as a whole, warmer water flowing in from the Channel mixed with the cooler waters of the Baltic and North Atlantic result in streams of widely varying temperatures within the current.
The mean residence time of water in the North sea is between 1 and two years.<ref name="SaS">[http://www.safetyatsea.se/index.php?art=2041&group=400 Safety At Sea: Currents in the North Sea]</ref> Water in the north is exchanged most quickly while water in the German Bight can flow in circles for years before being pulled northwards.
Fronts based on temperature, salinity, nutrients, and [[pollution]] can be clearly identified; they are more clearly defined in summer than in winter. Large fronts are the Frisian Front, which divides water coming from the North Atlantic from water originating in the English Channel, and the Danish Front, which divides southern coastal waters from water in the central North Sea. The inflow of water from large rivers mixes very slowly with North Sea water. Water from the Rhine and Elbe, for example, can still be clearly differentiated from sea water off the northwest coast of Denmark.
[[Image:Rivieren 4.46933E 51.88083N.jpg|thumb|right|200px|The mouth of the Rhine]]
{| class="wikitable sortable"
|+ | Influent Rivers of the North Sea
|- bgcolor="#efefef"
! River || Country || Discharge in [[cubic meter per second|m³/s]] || in [[cubic foot per second|cu ft/s]]
|-
|[[Rhine]] / [[Meuse River|Meuse]] || Netherlands || 2,524 || 89,134
|-
|[[Elbe]] || Germany || 856 || 30,229
|-
|[[Glomma]] || Norway || 603 || 21,295
|-
|[[IJsselmeer]] || Netherlands|| 555 || 19600
|-
|[[Weser]] || Germany || 358 || 12,643
|-
|[[Skjern Å]] || Denmark || 206 || 7275
|-
|[[Firth of Tay]] (includes [[River Tay]] and [[River Earn]]) || Scotland || 203 || 7169
|-
|[[Moray Firth]] (includes [[River Spey]] and [[River Ness]]) || Scotland || 168 || 5933
|-
|[[Scheldt]] || Belgium/Netherlands || 126 || 4450
|-
|[[Humber]] || England || 125 || 4415
|-
|[[River Forth|Forth]] || Scotland || 112 || 3955
|-
|[[Ems (river)|Ems]] || Germany || 88 || 3108
|-
|[[River Tweed|Tweed]] || England || 85 || 3002
|-
|[[Thames]] || England || 76 || 2684
|-
|}
===Tides===
The [[tides]] are caused by the tide wave from the North Atlantic, as the North Sea itself is too small and too flat to have its own tides. Ebb and flow alternate in a cycle of 12.5 hours. The tide wave, owing to the [[Coriolis effect]], flows around Scotland and then counter-clockwise along the English coast, reaching the German Bight some 12 hours after arriving in Scotland. In so doing, it runs around three [[amphidromic point]]s: a central point lies shortly before the Straits of Dover. It is formed by the tide wave which is transported through the English Channel. It influences the tides in the narrow area in the Southern Bight between southern England and the Netherlands. The other amphidromic system consists of two points close to each other, which form a tide wave. The two other points just off the coast of southern Norway and lying on a line between southern Denmark and the [[West Frisian Islands]] form one single area around which the tides flow. Its central point lies off the coast of Denmark at 55° 25' N, 5° 15' E.<ref Name="Statistics1"/>
As a result, the tidal range in southern Norway is less than half a metre (1.5 ft), but increases the further any given coast lies from the amphidromic point. Shallow coasts and the funnel effect of narrow straits increase the tidal range. The tidal range is at its greatest at [[The Wash]] on the English coast, where it reaches 6.80 m (22 ft). In shallow water areas, the real tidal range is strongly influenced by other factors, such as the position of the coast and the wind at any given moment or the action of storms. In river [[estuaries]], high water levels can considerably amplify the effect of high tide.
==Coasts==
The western coasts of the North Sea are jagged, as they were stripped by [[glacier]]s during the ice ages. The coastlines along the southernmost part are soft, covered with the remains of deposited glacials which were left directly by the ice or have been redeposited by the sea. The Norwegian mountains plunge into the sea, giving birth, north of [[Stavanger]], to deep [[fjord]]s and [[archipelago]]s. South of Stavanger, the coast softens, the islands become fewer. The Eastern Scottish coast is similar, though less marked than Norway. Starting from Flamborough Head in the northeast of England, the cliffs become lower and are composed of less resistant [[moraine]], which erodes more easily, so that the coasts have more rounded contours. In Holland, Belgium and in the East of England (East Anglia) the [[littoral]] is low and marshy. The East coast and south-east of the North Sea ([[Wadden Sea]]) have coastlines that are mainly sandy and straight owing to [[longshore currents]], particularly along Belgium and Denmark.<ref>[[:fr:Mer du Nord|Mer du Nord]]</ref>
===Northern fjords, skerries, and cliffs===
[[Image:Geirangerfjord (6-2007).jpg||thumb|right|200px|[[Geirangerfjord]], Norway]]
The northern North Sea coasts bear the impression of the enormous glaciers which covered them during the [[Ice Age]]s and created a split, craggy coastal landscape. [[Fjord]]s arose by the action of glaciers, which dragged their way through them from the highlands, cutting and scraping deep trenches in the land. During the subsequent rise in sea level, they filled with water. They very often display steep coastlines and are extremely deep for the North Sea. Fjords are particularly common on the coast of Norway.<ref>{{Citation
| last =EMECS International Center for the Environmental Management of Enclosed Coastal Seas
| first =Guidebook
| author-link =
| last2 =
| first2 =
| author2-link =
| title =5 North Sea
| date =
| year =
| url =http://www.emecs.or.jp/guidebook/eng/pdf/05north.pdf
| accessdate = 2007-07-24}}</reF>
[[Firth]]s are similar to fjords, but are generally shallower with broader bays in which small islands may be found. The glaciers that formed them influenced the land over a wider area and scraped away larger areas. Firths are to be found mostly on the Scottish and northern English coasts. Individual islands in the firths, or islands and the coast, are often joined up by [[sandbar]]s or spits made up of sand deposits known as “[[tombolo]]s”.<ref>{{Citation
| last =Home > Earth Heritage > Geological Conservation Review (GCR) > GCR Database
| first =
| author-link =
| last2 =
| first2 =
| author2-link =
| title =Coastal Geomorphology of Wales - GCR block
| date =
| year =
| url =http://www.jncc.gov.uk/earthheritage/gcrdb/gcrblock.asp?block=24
| accessdate = 2007-07-24}}</reF>
Towards the south the firths give way to a cliff coast, which was formed by the [[moraine]]s of Ice Age glaciers.<ref>{{Citation
| last =
| first =
| author-link =
| last2 =
| first2 =
| author2-link =
| title = Development of the coastline
| date =
| year =
| url =http://www.eastriding.gov.uk/aspirelinks/coastal/1development.pdf
| accessdate = 2007-07-24}}</reF> The horizontal impact of waves on the North Sea coast gives rise to eroded coasts. The eroded material is an important source of sediment for the mudflats on the other side of the North Sea.<ref>{{Citation
| last =CE3A8SMJGeologyforEngineers
| first =
| author-link =
| last2 =
| first2 =
| author2-link =
| title = Coasts: Geomorphology and Management
| date =
| year =
| url =http://www.tcd.ie/Geology/MAIN-PAGE/CE3A8/coast.pdf
| accessdate = 2007-07-24}}</reF>
The cliff landscape is interrupted by large [[estuary|estuaries]] with their corresponding mud and marshy flats disrupt, notably the Humber and the Thames, in southern England.
In southern Norway, as well as on the Swedish Skagerrak coast, [[skerry|skerries]] are to be found.<ref>{{Citation
| last = Drömresan
| first =Micke W
| author-link =
| last2 =
| first2 =
| author2-link =
| title =Sailing in Sweden and the Baltic
| date =
| year =1997-2005
| url =http://www.dromresan.com/english/index.shtml
| accessdate = 2007-07-24 }}</ref> Formed by similar action to that which created the fjords and firths, the glaciers in these places affected the land to an even greater extent, so that large areas were carried away. The coastal brim (''Strandflaten''), which is found especially in southern Norway, is a gently sloping lowland area between the sea and the mountains. It consists of plates of [[bedrock]], and often extends for kilometres, reaching under the sea, at a depth of only a few meters.
===Southern shoals and mudflats===
[[Image:Tidal flats.jpg|thumb|right|200px|Mudflats in Germany]]
The shallow-water coasts of the southern and eastern coast up to Denmark were formed by Ice Age activity, but their particular shape is determined for the most part by the sea and sediment deposits.<ref>{{Cite web
| publisher= Natural England
| title =Bridlington to Skegness: Habitat: Earth heritage
| date =
| year =
| url =http://www.english-nature.org.uk/science/natural/NA_HAbDetails.asp?Name=Bridlington+to+Skegness&N=101&H=65
| accessdate = 2007-07-24}}</ref>
The [[Wadden Sea]] stretches between [[Esbjerg]], Denmark in the north and [[Den Helder]], Netherlands in the west. This landscape is heavily influenced by the tides and important sections of it have been declared a National Park. The whole of the coastal zone is shallow; the tides flood large areas and uncover them again, constantly depositing sediments. The Southern Bight has been especially changed by land reclamation, as the Dutch have been especially active. The largest project of this type was the diking and reclamation of the [[IJsselmeer]].In the micro tidal area, (a [[tidal range]] of up to 1.35 m (4.43 ft)), such as on the Dutch or Danish coasts,<ref>{{Citation
| last = Drs. Teunis Louters
| title =Impact of Sea Level Rise on Dutch Wetlands: Morphological and ecological consequences over the next 50 -100 years
| date =
| year =1996
| url =http://www.netcoast.nl/publications/sealevel.doc
| accessdate = 2007-07-24 }}</ref>
barrier beaches with [[dune]]s are formed. In the mesotidal area (a tidal range of between 1.35 and 2.90 m (4.43-9.5 ft)), [[barrier island]]s are formed; in the macrotidal area (above 2.90 m (9.5 ft) tidal range), such as at the mouth of the Elbe, underwater sandbanks form.
The Dutch [[West Frisian Islands|West Frisian]] and the German [[East Frisian Islands]] are barrier islands. They arose along the breakers’ edge where the water surge piled up sediment, and behind which sediment was carried away by the breaking waves. Over time, sandplates arose, which finally were only covered by infrequent storm floods. Once plants began to colonize the sandbanks the land began to stabilise.<ref>{{Cite web
| publisher= WorldAtlas.com
| title =North Frisian Islands
| date =
| year =2007
| url =http://worldatlas.com/webimage/countrys/europe/denorthfrisian.htm
| accessdate = 2007-07-24}}</ref>
The [[North Frisian Islands]], on the other hand, arose from the remains of old [[Geestland]] islands, where the land was partially removed by storm floods and water action and then separated from the mainland. They are, therefore, often higher and their cores are less exposed to changes than the islands to the south. Beyond the core, however, the same processes are at work, particularly evident on [[Sylt]], where in the south of the island, a break threatens, whilst the [[harbour]] at [[List (village)|List]] silts up.<ref>{{Citation
| last = Ahrendt
| first =Kai
| author-link =
| last2 =
| first2 =
| author2-link =
| title =Expected Effects of Climatic Change on a Barrier Island - Case Study Sylt Island/German Bight
| date =
| year =
| url =http://www.iczm.de/sylt.pdf
| accessdate = 2007-07-24 }}</ref>
The Danish Islands, the next in the chain to the north, arose from sandbanks. Right up into the twentieth century, the silting up of the islands was a serious problem. To protect the islands, small woods were planted.
The island of [[Helgoland]] was not formed by sediment deposition; in fact, it is considerably older and is composed of Early [[Triassic]] [[sandstone]].
===Storm tides===
[[Image:Thames Barrier London.jpg|thumb|right|200px|[[Thames Barrier]], London]]
[[Storm tide]]s threaten, in particular, the coasts of the Netherlands, Belgium, Germany, and Denmark. These coasts are quite flat, so even a relatively small increase in the water levels is sufficient to put large stretches of land under water. Storms from the west are especially strong, so the most dangerous places are on the south-east coast. Over the years, floods caused by storm tides have cost hundreds of thousands of lives and have significantly helped to shape the coast. Until early modern times, the number of victims from a single storm tide could be in the tens of thousands, even exceeding a hundred thousand, though to what extent these historically-reported casualties are accurate can only be estimated with difficulty.
The first recorded storm tide flood was the ''Julianenflut'', on [[February 17]], [[1164]]. In its wake the [[Jadebusen]] began to form. Ancient records tell also of the First Marcellus Flood, which struck [[West Friesland (region)|West Frieslandin]] 1219. A storm tide in 1228 is recorded to have killed more than 100,000 people. The Second Marcellus Flood also known as the [[Grote Mandrenke]] in 1362 hit the entire southern coast of the North Sea. Chronicles of the time again record more than 100,000 deaths as large parts of the coast were lost permanently to the sea, including the now legendary town of [[Rungholt]] (see [[Lost city]]).
In the twentieth century the [[North Sea flood of 1953]] flooded several nations' coasts and cost more than 2000 lives.<ref>{{Citation
| last =Investigating Rivers
| title =Coastal Flooding: The great flood of 1953 - A case study
| date =
| year =
| url =http://www.naturegrid.org.uk/rivers/gt%20stour%20case%20study-pages/fld-cstl.html
| accessdate = 2007-07-24 }}</ref>
315 citizens of Hamburg died in the [[North Sea flood of 1962]]. The "Century Flood" of 1976 and the "North Frisian Flood" of 1981 brought the highest water levels measured to date on the North Sea coast, but because of the [[dike (construction)|dikes]] built and improved after the flood of 1962, these led only to property damage.<ref>{{Cite web
| author =home weather-uk
| title = press pack Ready-prepared articles on rainstorms, deluges, and floods
| date =
| year =
| url =http://www.weather-uk.com/press/flood.html
| accessdate = 2007-07-24}}</ref>
A storm surge occurred on November 9, 2007, causing some flooding. The conditions were likened to those that had caused the damage and large loss of life in 1953. Fortunately, in 2007,
nowhere near as much damage was caused although the [[Thames Barrier]] was closed twice to protect [[London]].
===Coastal preservation===
[[Image:Abschlussdeich Blickrichtung Nord.jpg|thumb|right|200px|The [[Afsluitdijk]] (Closure-dike) is a major dam in the Netherlands.]]
[[Image:Oosterscheldekering, Netherlands.JPG|thumb|right|200px|[[Oosterscheldekering]], North Sea Protection Works or Delta Works.]]
The southern coastal areas were originally amphibious. The land included countless islands and islets which had been divided by rivers, streams, and wetlands and areas of dry land were regularly flooded. In areas especially vulnerable to storm tides, people settled first on natural areas of high ground such as [[Spit (landform)|spits]] and [[Geestland]]. As early as 500 BC, people were constructing [[artificial dwelling hill]]s several meters high. It was only around the beginning of the [[High Middle Ages]] in 1200 AD that inhabitants began to connect single ring dikes into a dike line along the entire coast, thereby turning amphibious regions between the land and the sea into permanent solid ground.
The modern form of the dikes began to take form in the 17th and 18th centuries, built by private enterprises in the Netherlands. The Dutch dike builders exported their designs to other North Sea regions. The North Sea Floods of 1953 and 1962 were impetus for further raising of the dikes as well as the shortening of the dike line through land reclamation and river [[weir]]s so as to present as little surface area as possible to the punishment of the sea and the storms.<ref>{{Citation
| last = Compare Infobase Limited.
| first =
| author-link =
| last2 =
| first2 =
| author2-link =
| title =North Sea Protection Works - Seven Modern Wonders of World
| date =2006-2007
| year =
| url =http://www.allwondersoftheworld.com/seven-modern-wonders/north-sea-protection-works.html
| accessdate = 2007-07-24 }}</ref> Currently, 27% of the Netherlands is below sea level protected by dikes, dunes, and beach flats.<ref>{{Citation
| last =About, Inc., A part of The New York Times Company.
| first =
| author-link =
| last2 =
| first2 =
| author2-link =
| title =Dykes of the Netherlands
| date = January 30
| year = ©2007
| url =http://geography.about.com/od/specificplacesofinterest/a/dykes.htm
| accessdate =2007-07-19 }}</ref>
Coastal preservation today consists of several levels. The dike slope reduces the energy of the incoming sea, so that the dike itself does not receive the full impact. Dikes that lie directly on the sea are especially reinforced. The dikes have, over the years, been repeatedly raised, sometimes up to 10 m (32 ft) and have become flatter in order to better reduce the erosion of the waves. Modern dikes are up to 100 m (328 ft) across. Behind the dike, there runs an access road and generally a thinly inhabited area. In many places, another dike follows after several kilometers.
Where the dunes are sufficient to protect the land behind them from the sea, these dunes are planted with [[beach grass]] to protect them from erosion by wind, water, and foot traffic.<ref>{{Citation
| last =Pat Gowen NSAG
| first =NSAG
| author-link =
| last2 =
| first2 =
| author2-link =
| title =The North Sea Action Group on Britains new EA Flood Plain Maps
| date =31 December
| year = 2000
| url =http://members.aol.com/ruraleye/fpmap.htm
| accessdate = 2007-07-24 }}</ref>
''See also'':
*[[Afsluitdijk]]
*[[Delta Works]]
*[[Flood control in the Netherlands]]
*[[Thames barrier]]
*[[Zuiderzee Works]]
==Economy==
===Oil and gas===
{{details more|North Sea oil|List of oil and gas fields of the North Sea}}
[[Image:StatfjordA(Jarvin1982).jpg|right|thumb|200px|Oil platform Statfjord A with the flotel Polymarine]]
[[Image:Oil platform in the North Sea.jpg|thumb|200px|North Sea oil platforms]]
In 1958, geologists discovered a [[natural gas]] field in [[Slochteren]] in the Dutch province of [[Groningen (province)|Groningen]] and it was suspected that more fields lay under the North Sea. However, at this point, the rights to natural resource exploitation on the high seas were still under dispute.<ref>{{Cite web
| author = Hugo Manson
| publisher = Department of History, University of Aberdeen
| title =Brief History of North Sea Oil and Gas
| date =12-Jun-2006
| year =
| url =http://www.abdn.ac.uk/~wad009/about/nsoghist.shtml
| accessdate = 2007-07-24}}</ref>
Test drilling began in 1966 and, then in 1969, [[Phillips Petroleum Company]] discovered the [[Ekofisk oil field]] (now Norwegian), which at that point was one of the 20 largest in the world and turned out to be distinguished by valuable low-sulfur oil. Commercial exploitation began in 1971 with [[Petroleum tanker|tankers]] and after 1975 by a [[Pipeline transport|pipeline]] first to [[Cleveland, England]] and then after 1977 also to [[Emden, Germany]]. Since the discovery of [[North Sea oil]] in the 1970s, nicknames of [[Aberdeen]] have been the ''Oil Capital of Europe'' or the ''Energy Capital of Europe''.<ref name="uni-abdn">{{cite web|url=http://www.abdn.ac.uk/central/abdn/|title=About Aberdeen|publisher=University of Aberdeen|accessdate=2007-02-08}}</ref>
The exploitation of the North Sea oil reserves began just before the [[1973 oil crisis]], and the climb of international oil prices made the large investments needed for extraction much more attractive. In the 1980s and 1990s, further discoveries of large oil fields followed. Although the production costs are relatively high, the quality of the oil, the political stability of the region, and the nearness of important markets in western Europe has made the North Sea an important oil producing region. The largest single environmental catastrophe in the North Sea was the destruction of the offshore oil platform [[Piper Alpha]] in 1988 in which 167 people lost their lives.
With more than 450 [[oil platform]]s, the North Sea is the most important region in the world for offshore drilling. The British section of North Sea has the most platforms, followed by the Norwegian, Dutch, and Danish sections. Besides the Ekofisk oil field, the [[Statfjord oil field]] is also notable as it was the cause of the first pipeline to span the [[Norwegian trench]]. The largest natural gas field in the North Sea, Troll Field, lies in the Norwegian trench at a depth of 345 meters (1100 ft). A [[Troll A platform|giant platform]] was required to access it. The German section has only two oil platforms, the larger of the two being the [[Mittelplate]], and is the least developed North Sea border-country in this respect.
In 1999, extraction reached an all time high with nearly 6 million barrels (950,000 m³) of crude oil and 280,000,000 m³ (999,000,000 cu ft)of natural gas per day being taken.<ref>{{cite web
| last =
| first =
| authorlink =
| coauthors =
| title =An Analysis of the UK North Sea Production
| work =
| publisher =
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| url =http://home.entouch.net/dmd/northsea.htm
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| accessdate = 2007-12-09 }}</ref>Today, the North Sea is a well-developed natural resource area, in which few new large discoveries are likely to be made. All the large oil companies have been involved in the extraction. But in the last few years, large companies like [[Royal Dutch Shell|Shell]] and [[BP]] have discontinued extraction and, since 1999, the amount extracted has continually fallen due to depleted reserves.
The price of [[Brent Crude]], one of the first types of oil extracted from the North Sea, is used today as a standard price for comparison for crude oil from the rest of the world.
===Fishing===
{{main|Fishing in the North Sea}}
[[Image:Fischkutterquerinhafen.jpg|thumb|right|200px|A trawler in [[Nordstrand, Germany]]]]
Fishing in the North Sea is concentrated in the southern part of the coastal waters. The main method of fishing is [[trawling]].
Annual catches grew each year until the 1980s, when a high point of more than 3 million metric tons (3.3 million S/T) was reached. Since then, the numbers have fallen back to around 2.3 million tons (2.5 million S/T) annually with considerable differences between years. Besides the fish caught, it is estimated that 150,000 metric tons (165,000 S/T) of unmarketable [[by-catch]] are caught and around 85,000 metric tons (94,000 S/T) of dead and injured [[invertebrate]]s.<ref>{{cite web
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Royal Society of Edinburgh Inquiry into the Scottish Fishing Industry
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| url =http://www.royalsoced.org.uk/enquiries/scottishfisheries/evidence/IFFO_all.pdf
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In recent decades, [[overfishing]] has left many fisheries unproductive, disturbing the marine [[food chain]] dynamics and costing jobs in the fishing industry.<ref>Clover, Charles. 2004. ''The End of the Line: How overfishing is changing the world and what we eat''. Ebury Press, London. ISBN 0-09-189780-7 </ref> Herring, cod and plaice fisheries may soon face the same plight as mackerel fishing which ceased in the 1970s due to overfishing.<ref>{{Citation
| last =Summerschool on Coastal and Marine Management
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| title =Fisheries: North Sea
| date =
| year = 2005
| url =http://www.ikzm-d.de/inhalt.php?page=54,941
| accessdate = 2007-07-19}}</ref>
Since the 1960s, various regulations have attempted to protect the stocks of fish such as limited fishing times and limited numbers of fishing boats, among other regulations. However, these rules were never systematically enforced and did not bring much relief. Since then, the United Kingdom and Denmark, two important fishing nations, became members of the EU, and have attempted, with the help of the [[Common Fisheries Policy]], to bring the problem under control.<ref>{{Citation
| publisher = International Council for the Exploration of the Sea
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| title =North Sea Fish Stocks: Good and Bad News
| date =18 October
| year =2004
| url =http://www.ospar.org/eng/doc/pdfs/R2C2.pdf
| accessdate = 2007-07-19}}</ref>
===Mineral resources===
In addition to oil, gas and fish, the states along the North Sea also take millions of cubic meters per year of [[sand]] and [[gravel]] from the ocean floor. These are used for construction projects, sand for beaches, and coast protection. The largest extractors of sand and gravel in 2003 were the Netherlands (around 30 million m³ {322 million sq ft}) and Denmark (around 10 million m³ {110 million sq ft} from the North Sea).<ref>{{cite web
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| title =Report on 12th EMSAGG meeting New zoning information for England ...
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| publisher =European Marine Sand And Gravel Group
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| url =http://www.ciria.org/emsagg/pdf/emsaggissue8.pdf
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| accessdate = 2007-12-09 }}</reF>
[[Image:Amber Bernstein many stones.jpg|thumb|right|200px|Unpolished amber stones, in varying hues]]
Rolled pieces of [[amber]], usually small but occasionally of very large size, may be picked up on the east coast of England, having probably been washed up from deposits under the North Sea. [[Cromer]] is the best-known locality, but it occurs also on other parts of the [[Norfolk]] coast, such as [[Great Yarmouth]], as well as [[Southwold]], [[Aldeburgh]] and [[Felixstowe]] in [[Suffolk]], and as far south as [[Walton-on-the-Naze]] in [[Essex, England|Essex]], whilst northwards it is not unknown in [[Yorkshire]]. On the other side of the North Sea, amber is found at various localities on the coast of the [[Netherlands]] and Denmark. Amber was also found on the Baltic coast across northern Europe. Some of the amber districts of the Baltic and North Sea were known in prehistoric times, and led to early trade with the south of Europe through the [[Amber Road]].
===Renewable energy===
[[Image:DanishWindTurbines.jpg|thumb|right|200px|A Danish offshore windfarm]]
{{see|Renewable energy in Scotland}}
Due to the strong prevailing winds, countries on the North Sea, specifically England and Denmark, have used the areas near the coast of the sea for wind driven electricity production since the 1990s. The first [[wind turbine]]s appeared off the English coast near [[Blyth, Northumberland|Blyth]] in the year 2000 and then off the Danish coast in 2002 near [[Horns Rev]]. Others have been commissioned, including [[OWEZ]] and [[Scroby Sands wind farm|Scroby Sands]] and more are in the planning phase. Offshore [[wind farm]]s have met some resistance, for instance in Germany. Concerns have arisen about shipping collisions and damage to the ocean ecology, particularly by the construction of the foundations. Furthermore, the distance from consumers leads to considerable energy losses in transmission.<ref>{{Citation
| last =Danish Wind Industry Association
| first =
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| title =Offshore Wind Turbine Pictures
| date =1997-2004
| year =13 May 2004
| url =http://www.windpower.org/en/pictures/offshore.htm
| accessdate = 2007-07-24 }}</ref> Nonetheless, the first deep water turbines in Scotland are under commissioning for [[Talisman Energy]], who are installing two large machines 25 km (15 mi) offshore adjacent to the Beatrice oilfield. These turbines are 88 m (290 ft) high with the blades 63 m (210 ft) long and will have a capacity of 5 MW each, making them the largest in the world.<ref>{{cite web|url=http://www.beatricewind.co.uk/Uploads/Downloads/Beatrice%20FAQ%20Updated%2014.02.06.pdf|title=Talisman FAQ|accessdate=2007-02-06}}</ref><ref>{{cite web|url=http://www.reuk.co.uk/Worlds-Largest-Wind-Turbine-Generator.htm|title=REUK report on 'Worlds Largest Wind Turbine'|accessdate=2007-02-14}}</ref>
Energy production from the sea is still in its early stages. The southern parts of the North Sea, do not have tides, waves or currents strong enough to harness energy usefully. The Norwegian coast and the intersection with the [[Irish Sea]] could be found suitable for [[Wave power|waves]] or ocean currents to provide power. First attempts for a power plant deriving electricity from the waves from 2003-2005 in Denmark were given up. The European Marine Energy Centre (EMEC) based at [[Stromness]] in Orkney is a [[Scottish Government]]-backed research facility. They have installed a wave testing system at Billia Croo on the Orkney mainland and a tidal power testing station on the nearby island of [[Eday]].<ref>{{cite web|url=http://www.emec.org.uk/|title=EMEC|accessdate=2007-02-03}}</ref> A small pilot-facility for the production of [[blue energy]] exists in the Norwegian city of [[Trondheim]].<ref>{{Citation
| last =
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| title =Floating windmills - Hydro
| date =2005-11-02
| year =
| url =http://www.hydro.com/en/press_room/news/archive/2005_11/hywind_en.html
| accessdate = 2007-07-24 }}</ref>
===Tourism===
The beaches and coastal waters of the North Sea are popular destinations for tourists. The Belgian, Dutch, German and Danish coasts are especially developed for tourism. While many of the busiest British beach resorts are on the South Coast, the British East Coast also has several important beach resorts.
Windsurfing and sailing are popular sports because of the winds. Because of the strong tides and areas of still water, the North Sea is more difficult to sail than the Baltic or the Mediterranean. [[Mudflat hiking]], recreational fishing, and [[recreational diving|diving]], including [[wreck diving]], are all possible.
The climatic conditions on the North Sea coast are thought to be especially healthful. As early as the 19th century travellers used their stays on the North Sea coast as curative and restorative vacations (German:''Kur-Urlaub''). The sea air, temperature, wind, water, and sunshine are counted among the beneficial conditions that are said to activate the body's defences, improve circulation, strengthen the immune system, and have healing effects on the skin and the respiratory system. Besides the climate, [[thalassotherapy]] spas often use sea waters, mud, brine, algae, and sea salt for curative and restorative purposes.
One peculiarity of the North Sea tourism until the 1990s was the ''Butterfahrten''. These were trips past the German tariff barriers onto the high seas for the purpose of purchasing items much more cheaply than they could be bought in Germany itself. The name comes from the time when butter was an expensive commodity and could be purchased more cheaply from Denmark. Other important wares were the heavily taxed goods like tobacco, spirits, and perfume.
===Marine traffic===
{{seealso|List of North Sea ports}}
[[Image:ECT waalhaven bij nacht.jpg|thumb|right|200px|[[Rotterdam]], [[Netherlands]]]]
The North Sea is very important for marine traffic and experiences some of the densest concentrations of ships in the world. A number of great ports are located along its coasts: [[Rotterdam]], the [[World's busiest port by cargo tonnage| third busiest port in the world by tonnage]], [[Antwerp]] and [[Hamburg]], both in the top 25, [[Bremen]]/[[Bremerhaven]] and [[Port of Felixstowe|Felixstowe]], both in the top 30 busiest [[List of busiest container ports|container seaports]],<REF>[http://aapa.files.cms-plus.com/Statistics/WORLD%20PORT%20RANKINGS%202005.xls AAPA World Port Rankings 2005]</ref> as well as the Port of Bruges-Zeebrugge, Europe's leading [[RoRo]] port.
All major ports have easy access to the various sea lanes of the North Sea, which are monitored, well-regulated, and regularly dredged. Traffic in the North Sea can be difficult. Fishing boats, oil and gas platforms as well as merchant traffic from [[Ports of the Baltic Sea|Baltic ports]] share routes on the North Sea. The possibility of bottlenecks at the English Channel, which sees 400 vessels a day<ref>[[English Channel#Shipping]]</ref> and the Kiel Canal, which averages more than 100 per day plus sport traffic (2003 figure)<ref>Kiel Canal Annual Report 2000 http://www.kiel-canal.org/pages_english/kanal-info/verkehr/Annual_Report_2000.pdf</ref> can add to the difficulty. The North Sea coasts are home to numerous canals and canal systems to facilitate traffic between and among rivers, artificial harbours, and the sea. Notable canals include the [[North Sea Canal]], which shortened the connection between the port of [[Amsterdam]] to the North Sea<ref>{{Citation
| last =Kreukels T., Wever E. (ed)
| first =
| author-link =
| last2 =
| first2 =
| author2-link =
| title =North Sea Ports in Transition: Changing Tides? - -Kreukels T., Wever E. (ed)
| date =
| year =
| url =http://www.vangorcum.nl/nl/snpage.asp?ID=3655
| accessdate = 2007-07-24 }}</ref>,and the [[Kiel Canal]], the world's busiest artificial waterway, which connects the North Sea and the Baltic.
==See also==
*[[1931 Dogger Bank earthquake]]
*[[Doggerland]]
*[[List of languages of the North Sea]]
*[[North Sea Commission]]
*[[Portal:Geography|Geography Portal]]
*[[Portal:Nautical|Nautical Portal]]
==Further reading==
*''Bridging Troubled Waters : Conflict and Co-operation in the North Sea Region since 1550'' (2005, ISBN 8790982304)
*Ilyina, P Ilyina (2007) ''The fate of persistent organic pollutants in the North Sea.'' Springer. ISBN 9783540681625)
*Karlsdóttir, Hrefna M (2005) ''Fishing on common grounds : the consequences of unregulated fisheries of North Sea herring in the postwar period.'' ISBN 9185196622)
*''North Sea coast: landscape panoramas'' (2007, ISBN 9781877339653)
*''Rural History in the North Sea Area A State of the Art.'' (2007, ISBN 9782503510057)
*''Mesolithic studies in the North Sea Basin and beyond : proceedings of a conference held at Newcastle in 2003'' (2007, ISBN 1842172247)
*''Offshore wind energy in the North Sea Region : the state of affairs of offshore wind energy projects, national policies and economic, environmental and technological conditions in Denmark, Germany, The Netherlands, Belgium and the United Kingdom'' (2005, OCLC: 71640714)
==References==
{{reflist|2}}
==External links==
{{Commons|North Sea}}
{{wiktionary}}
*[http://www.eastsea.org/article3/report3.htm Etymology and History of names]
*[http://www.northsea.org/nsc/thematic_groups/environment/documents/members/nsceg_membprofiles_0606.pdf North Sea Commission Environment Group Member Profiles 2006]
*[http://www.swaen.com/old_map_images.htm?zoomifyImagePath=http://www.swaen.com/os/zoom/22834/ Old map : Manuscript chart of the North Sea, VOC, ca.1690] (high resolution zoomable scan)
*{{PDFlink|[http://www.ospar.org/eng/doc/pdfs/R2C2.pdf Overview of geography, hydrography and climate of the North Sea]|2.94 [[Mebibyte|MiB]]<!-- application/pdf, 3087547 bytes -->}}
*[http://mapserver.maptech.com/homepage/index.cfm?lat=53.8785302472&lon=2.27772288745&scale=1500000&zoom=50&type=0&icon=0&searchscope=dom&CFID=1719760&CFTOKEN=33728793&scriptfile=http://mapserver.maptech.com/homepage/index.cfm&latlontype=DMS Silver Pit chart]
*[http://news.bbc.co.uk/1/hi/sci/tech/4360815.stm Silver Pit theories]
*[http://www.searchanddiscovery.com/documents/2006/06013graversen/images/graversen.pdf''The Jurassic-Cretaceous North Sea Rift Dome and associated Basin Evolution'']
*[http://www.nordsoemuseet.dk/index.php?sprog=en The North Sea Museum] in [[Hirtshals]], [[Denmark]]*[http://www.arch.soton.ac.uk/ University of Southampton], [http://www.arch.soton.ac.uk/Research/Aggregates/index.htm ''Reconstruction of Submerged Landscapes'']
{{coord|56|N|03|E|scale:4000000_type:waterbody|display=title}}
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[[Category:North Sea]]
[[Category:Marginal seas of the Atlantic Ocean]]
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