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| Geography | |
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Main article: Geography of the North Sea
North
Sea
Norwegian
Sea
Sk
Ka
Eng Ch
Sk=Skagerrak Ka=Kattegat
Eng Ch=English Channel
The North Sea is bounded by the Orkney Islands and east coasts of England and Scotland to the west[1] and the northern and central European mainland to the east and south, including Norway, Denmark, Germany, the Netherlands, Belgium, and France.[2] In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean.[1][2] In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat,[2] narrow straits that separate Denmark from Norway and Sweden respectively.[1] In the north it is bordered by the Shetland Islands, and connects with the Norwegian Sea, which lies in the very north-eastern part of the Atlantic.[1][3]
It is more than 970 kilometres (600 mi) long and 580 kilometres (360 mi) wide, with an area of 750,000 square kilometres (290,000 sq mi) and a volume of 94,000 cubic kilometres (23,000 cu mi).[4] Around the edges of the North Sea are sizeable islands and archipelagos, including Shetland, Orkney, and the Frisian Islands.[2] The North Sea receives freshwater from a number of European continental watersheds, as well as the British Isles. A large part of the European drainage basin empties into the North Sea including water from the Baltic Sea. The largest and most important affecting the North Sea are the Elbe and the Rhine – Meuse watershed.[5] Around 185 million people live in the catchment area of the rivers that flow into the North Sea encompassing some highly industrialized areas.[6]
[edit] Tags:Elbe,Rhine,Meuse,Basin,Norway,Denmark,Germany,Netherlands,Belgium,France,England,Atlantic Ocean,European,English Channel,British,Norwegian,Sk,Ka,Eng Ch,Kattegat,Orkney Islands,Scotland,Central European,Straits Of Dover,Baltic Sea,Skagerrak,Shetland Islands,Norwegian Sea,Archipelagos,Shetland,Orkney,Frisian Islands,British Isles,Drainage Basin,Catchment Area,Mainland, | |
| Major features | |
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For the most part, the sea lies on the European continental shelf with a mean depth of 90 metres (300 ft).[1][7] The only exception is the Norwegian trench, which extends parallel to the Norwegian shoreline from Oslo to an area north of Bergen.[1] It is between 20 and 30 kilometres (12 and 19 mi) wide[1] and has a maximum depth of 725 metres (2,379 ft).[7]
The Dogger Bank, a vast moraine, or accumulation of unconsolidated glacial debris, rises to a mere 15 to 30 metres (50–100 ft) below the surface.[8][9] This feature has produced the finest fishing location of the North Sea.[1] The Long Forties and the Broad Fourteens are large areas with roughly uniform depth in fathoms, (forty fathoms and fourteen fathoms or 73 and 26 m deep respectively). These great banks and others make the North Sea particularly hazardous to navigate,[10] which has been alleviated by the implementation of satellite navigation systems.[11] The Devil's Hole lies 200 miles (320 km) east of Dundee, Scotland. The feature is a series of asymmetrical trenches between 20 and 30 kilometres (12 and 19 mi) long, 1 and 2 kilometres (0.62 and 1.2 mi) wide and up to 230 metres (750 ft) deep.[12]
[edit] Tags:Ems,Continental Shelf,Norwegian Trench,Oslo,Bergen,Dogger Bank,Long Forties,Broad Fourteens,Fathoms,Satellite Navigation Systems,Moraine,Fish, | |
| Extent | |
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The International Hydrographic Organization defines the limits of the North Sea as follows:[13]
On the Southwest. A line joining the Walde Lighthouse (France, 1°55'E) and Leathercoat Point (England, 51°10'N).[14]
On the Northwest. From Dunnet Head (3°22'W) in Scotland to Tor Ness (58°47'N) in the Island of Hoy, thence through this island to the Kame of Hoy (58°55'N) on to Breck Ness on Mainland (58°58'N) through this island to Costa Head (3°14'W) and to Inga Ness (59'17'N) in Westray through Westray, to Bow Head, across to Mull Head (North point of Papa Westray) and on to Seal Skerry (North point of North Ronaldsay) and thence to Horse Island (South point of the Shetland Islands).
On the North. From the North point (Fethaland Point) of the Mainland of the Shetland Islands, across to Graveland Ness (60°39'N) in the Island of Yell, through Yell to Gloup Ness (1°04'W) and across to Spoo Ness (60°45'N) in Unst island, through Unst to Herma Ness (60°51'N), on to the SW point of the Rumblings and to Muckle Flugga (60°51′N 0°53′W / 60.85°N 0.883°W / 60.85; -0.883) all these being included in the North Sea area; thence up the meridian of 0°53' West to the parallel of 61°00' North and eastward along this parallel to the coast of Norway, the whole of Viking Bank being thus included in the North Sea.
On the East. The Western limit of the Skagerrak [A line joining Hanstholm (57°07′N 83°6′E / 57.117°N 83.1°E / 57.117; 83.1) and the Naze (Lindesnes, 58°N 7°E / 58°N 7°E / 58; 7)].
[edit] Tags:International Hydrographic Organization,Walde Lighthouse,Leathercoat Point,Dunnet Head,Hoy,Costa Head,Westray,Papa Westray,North Ronaldsay,Horse Island,Yell,Unst,Herma Ness,Parallel Of 61°00' North, | |
| Temperature and salinity | |
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The average temperature in summer is 17 °C (63 °F) and 6 °C (43 °F) in the winter.[4] The average temperatures have been trending higher since 1988, which has been attributed to climate change.[15][16] Air temperatures in January range on average between 0 to 4 °C (32 to 39 °F) and in July between 13 to 18 °C (55 to 64 °F). The winter months see frequent gales and storms.[1]
The salinity averages between 34 to 35 grams of salt per litre of water.[4] The salinity has the highest variability where there is fresh water inflow, such as at the Rhine and Elbe estuaries, the Baltic Sea exit and along the coast of Norway.[17]
[edit] Tags:Climate Change,Fresh Water, | |
| Water circulation and tides | |
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Ocean currents mainly entering via the north entrance exiting along Norwegian coast
The main pattern to the flow of water in the North Sea is an anti-clockwise rotation along the edges.[18]
The North Sea is an arm of the Atlantic Ocean receiving the majority of ocean current from the northwest opening, and a lesser portion of warm current from the smaller opening at the English Channel. These tidal currents leave along the Norwegian coast.[19] Surface and deep water currents may move in different directions. Low salinity surface coastal waters move offshore, and deeper, denser high salinity waters move in shore.[20]
The North Sea located on the continental shelf has different waves than those in deep ocean water. The wave speeds are diminished and the wave amplitudes are increased. In the North Sea there are two amphidromic systems and a third incomplete amphidromic system.[21][22] In the North Sea the average tide difference in wave amplitude is between 0 to 8 metres (0 to 26 ft).[4]
The Kelvin tide of the Atlantic ocean is a semidiurnal wave that travels northward. Some of the energy from this wave travels through the English Channel into the North Sea. The wave still travels northward in the Atlantic Ocean, and once past the northern tip of Great Britain, the Kelvin wave turns east and south and once again enters into the North Sea.[23]
[edit] Tags:Great Britain,Ocean Currents,Anti-clockwise,Ocean Current,Amphidromic,Kelvin Wave, | |
| Coasts | |
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Main article: Coastline of the North Sea
The German North Sea coast
The eastern and western coasts of the North Sea are jagged, formed by glaciers during the ice ages. The coastlines along the southernmost part are covered with the remains of deposited glacial sediment.[1] The Norwegian mountains plunge into the sea creating deep fjords and archipelagos. South of Stavanger, the coast softens, the islands become fewer.[1] The eastern Scottish coast is similar, though less severe than Norway. From north east 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.[24][25] In Holland, Belgium and in the east of England (East Anglia) the littoral is low and marshy.[1] The east coast and south-east of the North Sea (Wadden Sea) have coastlines that are mainly sandy and straight owing to longshore drift, particularly along Belgium and Denmark.[26]
[edit] Tags:Fjords,Scottish,Glaciers,Ice Ages,North East Of England,East Anglia,Littoral,Wadden Sea,Longshore Drift, | |
| Coastal management | |
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Further information: Afsluitdijk, Delta Works, Flood control in the Netherlands, Thames barrier, and Zuiderzee Works
The Afsluitdijk (Closure-dike) is a major dam in the Netherlands
The southern coastal areas were originally amphibious flood plains and swampy land. In areas especially vulnerable to storm tides, people settled behind elevated levees and on natural areas of high ground such as spits and Geestland.[27]:[302,303] As early as 500 BC, people were constructing artificial dwelling hills higher than the prevailing flood levels.[27]:[306,308][28] 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.[27]
The modern form of the dikes supplemented by overflow and lateral diversion channels, began to appear in the 17th and 18th centuries, built in the Netherlands.[29] The North Sea Floods of 1953 and 1962 were impetus for further raising of the dikes as well as the shortening of the coast line so as to present as little surface area as possible to the punishment of the sea and the storms.[30] Currently, 27% of the Netherlands is below sea level protected by dikes, dunes, and beach flats.[31]
Coastal management today consists of several levels.[32] The dike slope reduces the energy of the incoming sea, so that the dike itself does not receive the full impact.[32] Dikes that lie directly on the sea are especially reinforced.[32] The dikes have, over the years, been repeatedly raised, sometimes up to 9 metres (30 ft) and have been made flatter to better reduce wave erosion.[33][34] 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.[35]
[edit] Tags:Thames,Wind,Zuiderzee Works,Afsluitdijk,Flood Plains,Spits,Geestland,Artificial Dwelling Hills,High Middle Ages,Coastal Management,Beach Grass,Storm Tides, | |
| Storm tides | |
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Main article: Storm tides of the North Sea
Zuid-Beveland, North Sea flood of 1953.
Storm tides threaten, in particular, the coasts of the Netherlands, Belgium, Germany, and Denmark and low lying areas of eastern England particularly around The Wash and Fens.[26] Storm surges are caused by changes in barometric pressure combined with strong wind created wave action.[36]
The first recorded storm tide flood was the Julianenflut, on 17 February 1164. In its wake the Jadebusen, (a bay on the coast of Germany), began to form. A storm tide in 1228 is recorded to have killed more than 100,000 people.[37] In 1362, the Second Marcellus Flood, also known as the Grote Manndränke, 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 lost city of Rungholt.[38] In the 20th century, the North Sea flood of 1953 flooded several nations' coasts and cost more than 2,000 lives.[39] 315 citizens of Hamburg died in the North Sea flood of 1962.[40]:[79,86]
[edit] Tags:Zuid-beveland,The Wash,Fens,Barometric Pressure, | |
| Tsunamis | |
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Though rare, the North Sea has been the site of a number of historically documented tsunamis. 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 metres (66 ft) high that swept through the North Sea, having the greatest effect on Scotland and the Faeroe Islands.[41][42] The Dover Straits earthquake of 1580 is among the first recorded earthquakes in the North Sea measuring between 5.6 and 5.9 on the Richter Scale. This event caused extensive damage in Calais both through its tremors and possibly triggered a tsunami, though this has never been confirmed. The theory is a vast underwater landslide in the English Channel was triggered by the earthquake, which in turn caused a tsunami.[43] The tsunami triggered by the 1755 Lisbon Earthquake reached Holland, although the waves had lost their destructive power. 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 small tsunami that flooded parts of the British coast.[43][44]
[edit] Tags:United Kingdom, | |
| Geology | |
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Main article: Geology of the North Sea
The North Sea between 34 million years ago and 28 million years ago, as Central Europe became dry land
Shallow epicontinental seas like the current North Sea have since long existed on the European continental shelf. The rifting that formed the northern part of the Atlantic Ocean during the Jurassic and Cretaceous periods, from about 150 million years ago, caused tectonic uplift in the British Isles.[45] Since then, a shallow sea has almost continuously existed between the highs of the Fennoscandian Shield and the British Isles.[46] This precursor of the current North Sea has grown and shrunk with the rise and fall of the eustatic sea level during geologic time. Sometimes it was connected with other shallow seas, such as the sea above the Paris Basin to the south-west, the Paratethys Sea to the south-east, or the Tethys Ocean to the south.[47]
Map showing hypothetical extent of Doggerland (c. 8,000 BC), which provided a land bridge between Great Britain and continental Europe
During the Late Cretaceous, about 85 million years ago, all of modern mainland Europe except for Scandinavia was a scattering of islands.[48] By the Early Oligocene, 34 to 28 million years ago, the emergence of Western and Central Europe had almost completely separated the North Sea from the Tethys Ocean, which gradually shrank to become the Mediterranean as Southern Europe and South West Asia became dry land.[49] The North Sea was cut off from the English Channel by a narrow land bridge until that was breached by at least two catastrophic floods between 450,000 and 180,000 years ago.[50][51] Since the start of the Quaternary period about 2.6 million years ago, the eustatic sea level has fallen during each glacial period and then risen again. Every time the ice sheet reached its greatest extent, the North Sea became almost completely dry. The present-day coastline formed after the Last Glacial Maximum when the sea began to flood the European continental shelf.[52]
In 2006 a bone fragment was found while drilling for oil in the north sea. Analysis indicated that it was a Plateosaurus from 199 to 216 million years ago. This was the deepest dinosaur fossil ever found and the first find for Norway.[53]
[edit] Tags:Scandinavia, | |
| Fish and shellfish | |
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Pacific oysters, blue mussels and cockles in the Wadden Sea in the Netherlands.
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.[54] Over 230 species of fish live in the North Sea. Cod, haddock, whiting, saithe, plaice, sole, mackerel, herring, pouting, sprat, and sandeel are all very common and are fished commercially.[54][55] Due to the various depths of the North Sea trenches and differences in salinity, temperature, and water movement, some fish such as blue-mouth redfish and rabbitfish reside only in small areas of the North Sea.[56]
Crustaceans are also commonly found throughout the sea. Norway lobster, deep-water prawns, and brown shrimp are all commercially fished, but other species of lobster, shrimp, oyster, mussels and clams all live in the North Sea.[54] Recently non-indigenous species have become established including the Pacific oyster and Atlantic jackknife clam.[55]
[edit] Tags: | |
| Birds | |
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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.[54] 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 Black legged Kittiwakes, Atlantic Puffins, Northern fulmars, and species of petrels, gannets, seaducks, loons (divers), cormorants, gulls, auks, and terns, and many other seabirds make these coasts popular for birdwatching.[54][55]
[edit] Tags:Ythan, | |
| Marine mammals | |
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A female bottlenose dolphin with her young in Moray Firth, Scotland
The North Sea is also home to marine mammals. Common seals, and Harbour porpoises can be found along the coasts, at marine installations, and on islands. The very northern North Sea islands such as the Shetland Islands are occasionally home to a larger variety of pinnipeds including bearded, harp, hooded and ringed seals, and even walrus.[57] North Sea cetaceans include various porpoise, dolphin and whale species.[55][58]
[edit] Tags: | |
| Flora | |
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Phytoplankton bloom in the North Sea.
Plant species in the North Sea include species of wrack, among them bladder wrack, knotted wrack, and serrated wrack. Algae, macroalgal, and kelp, such as oarweed and laminaria hyperboria, and species of maerl are found as well.[55] Eelgrass, formerly common in the entirety of the Wadden Sea, was nearly wiped out in the 20th century by a disease. Tags: | |
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