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The North Sea is a marginal, epeiric sea of the Atlantic Ocean on the European continental shelf. It is more than 600 miles long and 350 miles wide, with an area of around 222,000 square miles. 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 faults associated with these tectonic phenomena can still cause earthquakes and small tsunamis. The sea\'s coastal features are the result of glacial movements rather than tectonics. Deep fjords and sheer cliffs mark the coastline of the northern part of the North Sea, whereas the southern coasts consist of sandy beaches and mudflats. These flatter areas are particularly susceptible to flooding, especially as a result of storm tides. Elaborate systems of 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 Romans and the Vikings 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.
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The name of the North Sea originates from its relationship to the land of the Frisians. Frisia lies directly to the south of the North Sea, to the west of the East Sea (Oostzee, the Baltic Sea), to the north of the former South Sea (Zuiderzee, today\'s IJsselmeer) and the today-reclaimed 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.Common-place: Naming the Pacific, <http://www.common-place.org/vol-05/no-02/peterson/index.shtml>. Retrieved on 19 July 2007
From the point of view of the German 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" "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." [1] (from the Latin Mare Germanicum) was commonly used in 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.
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 Celtic populations.Germany The migration period, <http://www.britannica.com/eb/article-58084/Germany>. Retrieved on 24 July 2007
Viking expansion and raiding by century
The Viking Age began in 793 with the attack on Lindisfarne and for the next quarter-millinium 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 centered 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.
Painting of the Four Days Battle of 1666 by Willem van de Velde
Dutch power during her 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 long 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.
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 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 theater 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 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 minesweepers, and Fast Attack Craft.Campaigns of World War II, Naval History Homepage, Atlantic, WW2, U-boats, convoys, OA, OB, SL, HX, HG, Halifax, RCN ..., <http://www.naval-history.net/WW2CampaignsStartEurope.htm>. Retrieved on 24 July 2007 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.LemaireSoft, LemaireSoft\'s Naval Encyclopedia of World War 2: Hipper, <http://www.lemaire.happyhost.org/ship/edito/1950.html>. Retrieved on 24 July 2007 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 100 foot (30 m) submarine chasers. (see also: HNoMS Hitra).www.shetland-heritage.co.uk/shetlandbus/pages/the_operation.htm.
In the last years of the war and the first years thereafter, huge volumes of weapons were sunk in the North Sea. These comprised mainly grenades, land mines, naval mines, bazookas, cartridges, and some chemical weapons. Though estimates vary widely, hundreds of thousand tons of munitions were sunk.Koch, Marc & Ruck, Wolfgang, Securing and Remediation Concepts for Dumped Chemical and Conventional Munitions in the Baltic Sea, <http://www.dstl.gov.uk/conferences/cwd/2006/034.pdf>. Retrieved on 26 October 2007
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.
The Exclusive Economic Zones 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."The Multilaterals Project, The Fletcher School, Tufts University (29 April 1958), Convention on the Continental Shelf, Geneva., <http://fletcher.tufts.edu/multi/texts/BH366.txt>. Retrieved on 24 July 2007 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.International Court of Justice (Judgment of 20 February 1969), North Sea Continental Shelf Cases, <http://www.u-paris2.fr/cij/icjwww/idecisions/isummaries/icssummary690220.htm>. Retrieved on 24 July 2007
Environmental concerns led to the MARPOL 73/78 Accords, which created 25 mi 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 mudflats, which run along the coasts of the three countries on the southern edge of the North Sea.
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.Fisheries Centre of the University of British Columbia. 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 AtlanticOSPAR Commission (2004 -), OSPAR / The OSPAR Convention, <http://www.ospar.org/eng/html/1992-ospar-convention.htm>. Retrieved on 24 July 2007of 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 kilometers (222,000 sq mi) with a volume of around 54,000 cubic kilometers (13,000 cu mi). This places the North Sea at the 13th largest sea on the planet.Royal Belgian Institute of Natural Sciences, MUMM North Sea facts, <http://www.mumm.ac.be/EN/NorthSea/facts.php>. Retrieved on 19 July 2007
North Sea cliff
The bed of the North Sea forms two 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.Review of North Sea Basin development.
During the most recent glaciation, the 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."Invicta Media (30 March 2002;), Forming the Channel, <http://www.theotherside.co.uk/tm-heritage/background/channelform.htm>. Retrieved on 25 July 2007 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.Sample, Ian. "Breach of ice age lake made Britain an island", The Guardian, 19 July 2007. Retrieved on 2007-07-21.
The Storegga Slides 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.Axel Bojanowski, (October 11, 2006). Tidal Waves in Europe? Study Sees North Sea Tsunami Risk. Spiegel Online. Retrieved on 2007-07-24.Bondevik, Stein; Dawson, Sue; Dawson, Alastair; Lohne, Øystein (5 August 2003). "Record-breaking Height for 8000-Year-Old Tsunami in the North Atlantic". EOS, Transactions of the American Geophysical Union 84 (31): 289, 293. PMID. Retrieved on 2007-01-15.
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 landslides from earthquakes.Geology Shop, UK Earthquakes, <http://www.geologyshop.co.uk/ukequakes.htm>. Retrieved on 24 July 2007 Although not a site of major earthquakes or tsunamis, there are intraplate earthquakes which result in the uplifting of the continental crustBott, Martin H P; Bott, Jacqueline D J (Jan 2004). "Cenozoic uplift and earthquake belt of mainland Britain as a response to an underlying hot, low-density upper mantle (Abstract)". Journal of the Geological Society. Retrieved on 2007-07-24. causing landslides. 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.
The North Sea is located at a triple junction of three continental plates formed during the Palaeozoic: Avalonia, Laurentia and Baltica.Lyngsie, S B; Rasmussen, T M; Thybo, H (October 11, 2006). "Regional geological and tectonic structures of the North Sea area from potential field modelling". Tectonophysics 413: 147–170. Retrieved on 2007-07-24. Baltica is now the eastern coastline and the Scandinavian 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.
The Dogger Bank
The Norwegian trench reaches from the 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 erosional 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 morainic plate of the Dogger Bank rises up to 15 to 30 m deep.Maptech : Topo Maps Charts Navigation Software GPS and Online MapServer, <http://mapserver.maptech.com/homepage/index.cfm?lat=54.74456315454079&lon=2.3527509224287115&scale=1500000&zoom=50&type=0&icon=0&;height=498&searchscope=dom&CFID=1719760&CFTOKEN=33728793&scriptfile=http://mapserver.maptech.com/homepage/index.cfm&latlontype=DMS>. Retrieved on 20 July 2007
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 fathoms (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, centered 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 sizable islands and archipelagos, including the Shetland, Orkney, and Frisian islands.
Copepods 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 abour 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. OSPAR Quality Status Report for the Greater North Sea, <http://www.bmu.de/files/pdfs/allgemein/application/pdf/kapitel5_ospar_report.pdf>. Retrieved on 21 December 2007 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. Factors affecting the distribution Of North Sea fish, <http://www.ices.dk/marineworld/fishmap/pdfs/factors.pdf>. Retrieved on 9 December 2007
Crustaceans are also commonly found throughout the sea. Norway lobster, , and deep-water prawns and brown shrimp are all commercially fished, but other species of lobster, shrimp, oyster, mussels and clams are all found.
The coasts of the North Sea are home to nature reserves 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 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 fulmars, Black-legged Kittiwakes, Atlantic puffins, razorbills, and a variety of species of petrels, gannets, seaducks, loons (divers), cormorants, gulls, auks, and terns, and many other seabirds make these coasts popular for birdwatching.
| 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
The North Sea is also home to a variety of marine mammals. Common seals, grey seals 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, harp, hooded and ringed seals, and even walrus.
| 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 North Sea cetaceans include Harbour porpoises, common dolphins, bottlenose dolphins, Risso\'s dolphins, long-finned pilot whales and white-beaked dolphins, minke whales, killer whales, and sperm whales Whales and dolphins in the North Sea \'on the increase\', 2 April, <http://www.ncl.ac.uk/press.office/press.release/content.phtml?ref=1112607082>. Retrieved on 21 December 2007
Historically, flamingos, pelicans, and Great Auk could be found along the southern shores of the North SeaFollowing in the footsteps of the North Sea flamingo. Retrieved on 2008-01-04. . 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 whales, sturgeon, shad, rays, skates 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. OSPAR Quality Status Report for the Greater North Sea, <http://www.bmu.de/files/pdfs/allgemein/application/pdf/kapitel5_ospar_report.pdf>. Retrieved on 21 December 2007
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.
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 thousand (ppt) around river mouths and up to 32 to 35 ppt in the northern North Sea, 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.
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.
Around 185 million people live in the catchment area of the rivers that flow into the North Sea. OSPAR Quality Status Report 2000, <http://www.ospar.org/eng/html/welcome.html>. Retrieved on 21 December 2007 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. OSPAR Quality Status Report 2000, <http://www.ospar.org/eng/html/welcome.html>. Retrieved on 21 December 2007 This area contains one of the world\'s greatest concentrations of industry.
The main pattern to the flow of water in the North Sea is a counter-clockwise rotation along the edges.Department for the Environment, Food and Rural Affairs, UK: Marine: Cleaner Seas report 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. 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.Safety At Sea: Currents in the North Sea 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.
The mouth of the Rhine
| River | Country | Discharge in m³/s | in cu ft/s |
|---|---|---|---|
| Rhine / 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 |
| Forth | Scotland | 112 | 3955 |
| Ems | Germany | 88 | 3108 |
| Tweed | England | 85 | 3002 |
| Thames | England | 76 | 2684 |
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 points: 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.
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.
The western coasts of the North Sea are jagged, as they were stripped by glaciers 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 fjords and archipelagoes. 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.Mer du Nord
.jpg/58px-Geirangerfjord (6-2007).jpg)
Geirangerfjord, Norway
The northern North Sea coasts bear the impression of the enormous glaciers which covered them during the Ice Ages and created a split, craggy coastal landscape. Fjords 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.EMECS International Center for the Environmental Management of Enclosed Coastal Seas, Guidebook, 5 North Sea, <http://www.emecs.or.jp/guidebook/eng/pdf/05north.pdf>. Retrieved on 24 July 2007
Firths 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 sandbars or spits made up of sand deposits known as “tombolos”.Home > Earth Heritage > Geological Conservation Review (GCR) > GCR Database, Coastal Geomorphology of Wales - GCR block, <http://www.jncc.gov.uk/earthheritage/gcrdb/gcrblock.asp?block=24>. Retrieved on 24 July 2007
Towards the south the firths give way to a cliff coast, which was formed by the moraines of Ice Age glaciers.Development of the coastline, <http://www.eastriding.gov.uk/aspirelinks/coastal/1development.pdf>. Retrieved on 24 July 2007 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.CE3A8SMJGeologyforEngineers, Coasts: Geomorphology and Management, <http://www.tcd.ie/Geology/MAIN-PAGE/CE3A8/coast.pdf>. Retrieved on 24 July 2007 The cliff landscape is interrupted by large 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, skerries are to be found.Drömresan, Micke W, Sailing in Sweden and the Baltic, <http://www.dromresan.com/english/index.shtml>. Retrieved on 24 July 2007 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 kilometers, reaching under the sea, at a depth of only a few meters.
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.Bridlington to Skegness: Habitat: Earth heritage. Natural England. Retrieved on 2007-07-24. 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,Drs. Teunis Louters, Impact of Sea Level Rise on Dutch Wetlands: Morphological and ecological consequences over the next 50 -100 years, <http://www.netcoast.nl/publications/sealevel.doc>. Retrieved on 24 July 2007 barrier beaches with dunes are formed. In the mesotidal area (a tidal range of between 1.35 and 2.90 m (4.43-9.5 ft)), barrier islands 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 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.North Frisian Islands. WorldAtlas.com (2007). Retrieved on 2007-07-24.
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 harbor at List silts up.Ahrendt, Kai, Expected Effects of Climatic Change on a Barrier Island - Case Study Sylt Island/German Bight, <http://www.iczm.de/sylt.pdf>. Retrieved on 24 July 2007 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.
Thames Barrier, London
Storm tides 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 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.Investigating Rivers, Coastal Flooding: The great flood of 1953 - A case study, <http://www.naturegrid.org.uk/rivers/gt%20stour%20case%20study-pages/fld-cstl.html>. Retrieved on 24 July 2007 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 dikes built and improved after the flood of 1962, these led only to property damage.home weather-uk. press pack Ready-prepared articles on rainstorms, deluges, and floods. Retrieved on 2007-07-24. 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.
The Afsluitdijk (Closure-dike) is a major dam in the Netherlands.
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 spits and Geestland. As early as 500 BC, people were constructing artificial dwelling hills 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 weirs so as to present as little surface area as possible to the punishment of the sea and the storms.Compare Infobase Limited. (2006-2007), North Sea Protection Works - Seven Modern Wonders of World, <http://www.allwondersoftheworld.com/seven-modern-wonders/north-sea-protection-works.html>. Retrieved on 24 July 2007 Currently, 27% of the Netherlands is below sea level protected by dikes, dunes, and beach flats.About, Inc., A part of The New York Times Company. (January 30), Dykes of the Netherlands, <http://geography.about.com/od/specificplacesofinterest/a/dykes.htm>. Retrieved on 19 July 2007
Coastal preservation today consists of several levels. The dike slope reduces the energy of the incoming sea, so
