The Strait of Dover or Dover Strait, historically known as the Dover Narrows, is the strait at the narrowest part of the English Channel, marking the boundary between the Channel and the North Sea, and separating Great Britain from continental Europe. The shortest distance across the strait, at approximately 20 miles (32 kilometres), is from the South Foreland, northeast of Dover in the English county of Kent, to Cap Gris Nez, a cape near to Calais in the French département of Pas-de-Calais. Between these points lies the most popular route for cross-channel swimmers. The entire strait is within the territorial waters of France and the United Kingdom, but a right of transit passage under the United Nations Convention on the Law of the Sea allows vessels of other nations to move freely through the strait.
| Dover Strait | |
|---|---|
 View from France across the Strait of Dover towards the English coast  | |
| Location | North Sea–English Channel (Atlantic Ocean) |
| Coordinates | 51°00′N 1°30′E / 51.000°N 1.500°E |
| Type | Strait |
| Basin countries | France United Kingdom |
| Min. width | 20.5 miles (33.0 km) |
| Average depth | 150 feet (46 m) |
| Max. depth | 68 m (223 ft) |
On a clear day, it is possible to see the opposite coastline of England from France and vice versa with the naked eye, with the most famous and obvious sight being the White Cliffs of Dover from the French coastline and shoreline buildings on both coastlines, as well as lights on either coastline at night, as in Matthew Arnold's poem "Dover Beach".
Shipping traffic
Most maritime traffic between the Atlantic Ocean and the North Sea and Baltic Sea passes through the Strait of Dover, rather than taking the longer and more dangerous route around the north of Scotland. The strait is one of the busiest international seaways in the world, used by over 400 commercial vessels daily. This has made traffic safety a critical issue, with HM Coastguard and the Maritime Gendarmerie maintaining a 24-hour watch over the strait and enforcing a strict regime of shipping lanes.
In addition to the intensive north-east to south-west traffic, the strait is crossed from north-west to south-east by ferries linking Dover to Calais and Dunkirk. Until 1994 these provided the only route across it except for air transport. The Channel Tunnel now provides an alternative route, crossing beneath the strait at an average depth of 45 m (148 ft) below the seabed.
The town of Dover gives its name to one of the sea areas of the British Shipping Forecast.
Geological formation
The formation of strait was through scouring by erosion. It had for many millennia (since the last warm interglacial) been a land bridge that linked the Weald in Great Britain to the Boulonnais in the Pas de Calais. Though pitted by troughs and rivers, the English Channel was almost mainly land at the height of the last ice age. The predominant geology of both and of the seafloor is chalk. Although somewhat resistant to erosion, erosion of both coasts has created the famous white cliffs of Dover in the UK and the Cap Blanc Nez in France. The Channel Tunnel was bored through solid chalk – compacted remains of sea creatures and marine-deposited, ground up calciferous rock/soil debris.
The Rhine (as the Urstrom) flows northeast into the North Sea as the sea (covering most of the Netherlands) fell during the start of the first of the Pleistocene Ice Ages. The new ice unusually created a dam from Scandinavia to Scotland, and the Rhine, combined with the Thames and drainage from much of north Europe, created a vast lake behind the dam, which eventually spilled over the Weald into the English Channel. This overflow followed by further scouring became recognisably the Short Straits (an alternative name for this strait) about 425,000 years ago. A narrow deep channel along the middle of the strait is the remnants of the main (summer) outflow of the northern Ustrom glacial lake (a collect for other then-seasonal rivers, in winter iced up, such as the Thames and Weser) in the last Ice Age. A deposit in East Anglia marks the old preglacial northward course of the Urstrom-Thames when it also drained Doggerland. The deep sea floor east of Lincolnshire and East Yorkshire, connecting to the Atlantic via the Pentland Firth in the last glaciation (of over 300,000 years) is a necessary pre-condition for the relatively late cutting through of the Strait to the south.
December 2002
Likewise, a 2007 study concluded that the Strait was formed by erosion caused by two major floods. The first was about 425,000 years ago, when an ice-dammed lake in the southern North Sea overflowed and broke the Weald-Artois (Boulonnais) chalk range in a catastrophic erosion and flood event. Consequently the ice-age-muted flows from the Thames and Scheldt flowed through the gap into the English Channel/Inlet, but the Meuse and Rhine still flowed without any significant link to the inlet (such as today's IJssel distributary supports). In a second flood about 225,000 years ago supported by glaciers extending from areas then land such as the Zuiderzee, the Meuse and Rhine were ice-dammed into a lake that broke catastrophically through a high weak barrier (perhaps chalk, or an end-moraine left by the ice sheet). Both floods cut massive flood channels in the dry bed of the English Channel, somewhat like the Channeled Scablands or the Wabash River in the USA. A further update in 2017 attributed a series of previously described underwater holes in the Channel floor, "100m deep" and in places "several kilometres in diameter", to lake water plunging over a rock ridge causing isolated depressions or plunge pools. The melting ice and rising sea levels submerged Doggerland, the area linking Britain to France, around 6,500–6,200 BCE.
The Lobourg strait, the deepest part the strait, runs its 6 km (4 mi)wide slash on a NNE–SSW axis. Nearer to the French coast than to the English, it borders the Varne sandbank (shoals) where it plunges to 68 m (223 ft) and further south, the Ridge bank (shoals) (French name "Colbart") with a maximum depth of 62 m (203 ft).
Marine wildlife
The depth of the strait varies between 68 m (223 ft) at the Lobourg strait and 20 m (66 ft) at the highest banks. The seabed forms successions of three habitats:
- rocky zones relatively deserted by ships wanting to spare their nets
- sandy flats
- sub-aqueous dunes.
The strong tidal currents of the strait at depth slow around its rocky masses as these stimulate countercurrents and deep, calm pockets where many species can find shelter. In these calmer lee zones, the water is clearer than in the rest of the strait; thus algae can grow despite the 46 m (151 ft) average depth. They help increase diversity in the local species – some of which are endemic to the strait. Moreover, this is a transition zone for the species of the Atlantic Ocean and those of the southern part of the North Sea.
This mix of various environments promotes a wide variety of wildlife.
The Ridens de Boulogne, a 10–20 m (33–66 ft) deep rocky shoal, partially sand-capped,15 nmi (28 km; 17 mi) west of Boulogne, boasts the highest profusion of maerl in the strait.
Thus some 682 km2 (263 sq mi) of the strait is classified as a Natura 2000 protection zone named Ridens et dunes hydrauliques du Pas de Calais (Ridens and sub-aqueous dunes of the Dover Strait). This includes the sub-aqueous dunes of Varne, Colbart, Vergoyer and Bassurelle, the Ridens de Boulogne, and the Lobourg channel which provides calmer and clearer waters due to its depth reaching 68 m (223 ft).
Unusual crossings
Many crossings other than in conventional vessels have been attempted, including by pedalo, jetpack, bathtub, amphibious vehicle and more commonly by swimming. Since French law bans many of them, unlike English law, most such crossings originate in England.[citation needed]
Ice
In the late 17th century during the "Little Ice Age", there were reports of severe winter ice in the English Channel and Strait of Dover, including a case in 1684 of only a league of open water remaining between Dover and Calais.
See also
- Battle of Dover Strait (1916)
- Battle of Dover Strait (1917)
- Calais Lighthouse
- South Foreland Lighthouse
- Cap Gris-Nez
- France–UK border
- Port of Boulogne-sur-Mer
Notes
References
- Crystal, David, ed. (1999). "English Channel". Cambridge Paperback Encyclopedia (3rd ed.). Cambridge University Press. p. 1080. ISBN 978-0521668002.
- López Martín, Ana G. (2010). International Straits: Concept, Classification and Rules of Passage (Illustrated ed.). Springer Science & Business Media. p. 95 & 102. ISBN 9783642129063.
- Glegg, G; Jefferson, R; Fletcher, S (30 June 2015). Sheppard, Charles; Galgani, Francois; Hutchings, Pat; Quintino, Victor (eds.). "Marine Governance in the English Channel (La Manche): Linking Science and Management". Marine Pollution Bulletin. 95 (2): 707–718. doi:10.1016/j.marpolbul.2015.02.020. hdl:10026.1/3662. PMID 25819447.
- Van Dyke, Jon M. (2009). "Transit Passage Through International Strait". In Chircop, Aldo; McDorman, Ted; Rolstons, Susan (eds.). The Future of Ocean Regime-Building. Brill (1618). pp. 175–232. ISBN 978-9004172678.
- "The Channel Navigation Information Service (CNIS)". Archived from the original on 17 October 2007.
- "English Channel | channel, Europe". Encyclopædia Britannica. Archived from the original on 3 April 2017. Retrieved 16 May 2017.
- Gupta, Sanjeev; Collier, Jenny S.; Palmer-Felgate, Andy; Potter, Graeme (2007). "Catastrophic Flooding Origin of Shelf Valley Systems in the English Channel". Nature. 448 (7151): 342–5. Bibcode:2007Natur.448..342G. doi:10.1038/nature06018. PMID 17637667. S2CID 4408290.
- Gibbard, Philip (19 July 2007). "Europe Cut Adrift". Nature. 448 (7151): 259–60. Bibcode:2007Natur.448..259G. doi:10.1038/448259a. PMID 17637645.
- Morelle, Rebecca (4 April 2017). "Evidence of Ancient 'Geological Brexit' Revealed". BBC News:Science & Environment. Retrieved 6 April 2017.
- "Pas de Calais – Dover Strait". sea-seek.com.
- "CoastView – What happens offshore?". GEOSYNTH-Project. University of Sussex.
- "Underwater video of the ridens". YouTube.
- Davoult, D.; Richard, A. (1988). "Les Ridens, haut-fond rocheux isolé du Pas de Calais: un peuplement remarquable" [The Ridens, Rocky Shallows in the Center of the Channel: A Distinguished Settlement]. Cahiers de Biologie Marine (in French). 29 (1): 93–107.
- "Richesses de la mer" [Richness of the sea] (PDF) (in French). Picardy Estuaries and Opal Sea Marine Natural Park.
- "Ridens et dunes hydrauliques du Pas de Calais" (in French). Natura 2000.
- "The Great Frost of 1683-4". www.pastpresented.info. Retrieved 20 March 2020.
- "Notes and Queries". Notes and Queries. Second Series. 11: 219. 16 March 1861 – via archive.org.
- The World of Wonders: A Record of Things Wonderful in Nature, Science, and Art. London: Cassel Petter & Galpin. 1869.
External links
- Channel Navigation Information Service
- Channel Swimming & Piloting Federation
- Channel Swimming Association
- Depth Chart showing straits and former course of Rhine
The Strait of Dover or Dover Strait historically known as the Dover Narrows is the strait at the narrowest part of the English Channel marking the boundary between the Channel and the North Sea and separating Great Britain from continental Europe The shortest distance across the strait at approximately 20 miles 32 kilometres is from the South Foreland northeast of Dover in the English county of Kent to Cap Gris Nez a cape near to Calais in the French departement of Pas de Calais Between these points lies the most popular route for cross channel swimmers The entire strait is within the territorial waters of France and the United Kingdom but a right of transit passage under the United Nations Convention on the Law of the Sea allows vessels of other nations to move freely through the strait Dover StraitView from France across the Strait of Dover towards the English coastLocationNorth Sea English Channel Atlantic Ocean Coordinates51 00 N 1 30 E 51 000 N 1 500 E 51 000 1 500TypeStraitBasin countriesFrance United KingdomMin width20 5 miles 33 0 km Average depth150 feet 46 m Max depth68 m 223 ft On a clear day it is possible to see the opposite coastline of England from France and vice versa with the naked eye with the most famous and obvious sight being the White Cliffs of Dover from the French coastline and shoreline buildings on both coastlines as well as lights on either coastline at night as in Matthew Arnold s poem Dover Beach Shipping trafficAutomatic Identification System display showing traffic in the strait in 2006 Most maritime traffic between the Atlantic Ocean and the North Sea and Baltic Sea passes through the Strait of Dover rather than taking the longer and more dangerous route around the north of Scotland The strait is one of the busiest international seaways in the world used by over 400 commercial vessels daily This has made traffic safety a critical issue with HM Coastguard and the Maritime Gendarmerie maintaining a 24 hour watch over the strait and enforcing a strict regime of shipping lanes In addition to the intensive north east to south west traffic the strait is crossed from north west to south east by ferries linking Dover to Calais and Dunkirk Until 1994 these provided the only route across it except for air transport The Channel Tunnel now provides an alternative route crossing beneath the strait at an average depth of 45 m 148 ft below the seabed The town of Dover gives its name to one of the sea areas of the British Shipping Forecast Geological formationMap showing the hypothetical extent of Doggerland c 10 000 BCE which provided a land bridge between Great Britain and continental Europe The formation of strait was through scouring by erosion It had for many millennia since the last warm interglacial been a land bridge that linked the Weald in Great Britain to the Boulonnais in the Pas de Calais Though pitted by troughs and rivers the English Channel was almost mainly land at the height of the last ice age The predominant geology of both and of the seafloor is chalk Although somewhat resistant to erosion erosion of both coasts has created the famous white cliffs of Dover in the UK and the Cap Blanc Nez in France The Channel Tunnel was bored through solid chalk compacted remains of sea creatures and marine deposited ground up calciferous rock soil debris The Rhine as the Urstrom flows northeast into the North Sea as the sea covering most of the Netherlands fell during the start of the first of the Pleistocene Ice Ages The new ice unusually created a dam from Scandinavia to Scotland and the Rhine combined with the Thames and drainage from much of north Europe created a vast lake behind the dam which eventually spilled over the Weald into the English Channel This overflow followed by further scouring became recognisably the Short Straits an alternative name for this strait about 425 000 years ago A narrow deep channel along the middle of the strait is the remnants of the main summer outflow of the northern Ustrom glacial lake a collect for other then seasonal rivers in winter iced up such as the Thames and Weser in the last Ice Age A deposit in East Anglia marks the old preglacial northward course of the Urstrom Thames when it also drained Doggerland The deep sea floor east of Lincolnshire and East Yorkshire connecting to the Atlantic via the Pentland Firth in the last glaciation of over 300 000 years is a necessary pre condition for the relatively late cutting through of the Strait to the south NASA Satellite image December 2002 Likewise a 2007 study concluded that the Strait was formed by erosion caused by two major floods The first was about 425 000 years ago when an ice dammed lake in the southern North Sea overflowed and broke the Weald Artois Boulonnais chalk range in a catastrophic erosion and flood event Consequently the ice age muted flows from the Thames and Scheldt flowed through the gap into the English Channel Inlet but the Meuse and Rhine still flowed without any significant link to the inlet such as today s IJssel distributary supports In a second flood about 225 000 years ago supported by glaciers extending from areas then land such as the Zuiderzee the Meuse and Rhine were ice dammed into a lake that broke catastrophically through a high weak barrier perhaps chalk or an end moraine left by the ice sheet Both floods cut massive flood channels in the dry bed of the English Channel somewhat like the Channeled Scablands or the Wabash River in the USA A further update in 2017 attributed a series of previously described underwater holes in the Channel floor 100m deep and in places several kilometres in diameter to lake water plunging over a rock ridge causing isolated depressions or plunge pools The melting ice and rising sea levels submerged Doggerland the area linking Britain to France around 6 500 6 200 BCE The Lobourg strait the deepest part the strait runs its 6 km 4 mi wide slash on a NNE SSW axis Nearer to the French coast than to the English it borders the Varne sandbank shoals where it plunges to 68 m 223 ft and further south the Ridge bank shoals French name Colbart with a maximum depth of 62 m 203 ft Marine wildlifeNASA Terra satellite image March 2001 The depth of the strait varies between 68 m 223 ft at the Lobourg strait and 20 m 66 ft at the highest banks The seabed forms successions of three habitats rocky zones relatively deserted by ships wanting to spare their nets sandy flats sub aqueous dunes The strong tidal currents of the strait at depth slow around its rocky masses as these stimulate countercurrents and deep calm pockets where many species can find shelter In these calmer lee zones the water is clearer than in the rest of the strait thus algae can grow despite the 46 m 151 ft average depth They help increase diversity in the local species some of which are endemic to the strait Moreover this is a transition zone for the species of the Atlantic Ocean and those of the southern part of the North Sea This mix of various environments promotes a wide variety of wildlife The Ridens de Boulogne a 10 20 m 33 66 ft deep rocky shoal partially sand capped 15 nmi 28 km 17 mi west of Boulogne boasts the highest profusion of maerl in the strait Thus some 682 km2 263 sq mi of the strait is classified as a Natura 2000 protection zone named Ridens et dunes hydrauliques du Pas de Calais Ridens and sub aqueous dunes of the Dover Strait This includes the sub aqueous dunes of Varne Colbart Vergoyer and Bassurelle the Ridens de Boulogne and the Lobourg channel which provides calmer and clearer waters due to its depth reaching 68 m 223 ft Unusual crossingsMany crossings other than in conventional vessels have been attempted including by pedalo jetpack bathtub amphibious vehicle and more commonly by swimming Since French law bans many of them unlike English law most such crossings originate in England citation needed IceIn the late 17th century during the Little Ice Age there were reports of severe winter ice in the English Channel and Strait of Dover including a case in 1684 of only a league of open water remaining between Dover and Calais See alsoBattle of Dover Strait 1916 Battle of Dover Strait 1917 Calais Lighthouse South Foreland Lighthouse Cap Gris Nez France UK border Port of Boulogne sur MerNotesFrench Pas de Calais pɑ d e kalɛ Strait of Calais Picard Pas d Cales Dutch Nauw van Calais ˈnʌu vɑŋ kaːˈlɛː or less used Straat van Dover ReferencesCrystal David ed 1999 English Channel Cambridge Paperback Encyclopedia 3rd ed Cambridge University Press p 1080 ISBN 978 0521668002 Lopez Martin Ana G 2010 International Straits Concept Classification and Rules of Passage Illustrated ed Springer Science amp Business Media p 95 amp 102 ISBN 9783642129063 Glegg G Jefferson R Fletcher S 30 June 2015 Sheppard Charles Galgani Francois Hutchings Pat Quintino Victor eds Marine Governance in the English Channel La Manche Linking Science and Management Marine Pollution Bulletin 95 2 707 718 doi 10 1016 j marpolbul 2015 02 020 hdl 10026 1 3662 PMID 25819447 Van Dyke Jon M 2009 Transit Passage Through International Strait In Chircop Aldo McDorman Ted Rolstons Susan eds The Future of Ocean Regime Building Brill 1618 pp 175 232 ISBN 978 9004172678 The Channel Navigation Information Service CNIS Archived from the original on 17 October 2007 English Channel channel Europe Encyclopaedia Britannica Archived from the original on 3 April 2017 Retrieved 16 May 2017 Gupta Sanjeev Collier Jenny S Palmer Felgate Andy Potter Graeme 2007 Catastrophic Flooding Origin of Shelf Valley Systems in the English Channel Nature 448 7151 342 5 Bibcode 2007Natur 448 342G doi 10 1038 nature06018 PMID 17637667 S2CID 4408290 Gibbard Philip 19 July 2007 Europe Cut Adrift Nature 448 7151 259 60 Bibcode 2007Natur 448 259G doi 10 1038 448259a PMID 17637645 Morelle Rebecca 4 April 2017 Evidence of Ancient Geological Brexit Revealed BBC News Science amp Environment Retrieved 6 April 2017 Pas de Calais Dover Strait sea seek com CoastView What happens offshore GEOSYNTH Project University of Sussex Underwater video of the ridens YouTube Davoult D Richard A 1988 Les Ridens haut fond rocheux isole du Pas de Calais un peuplement remarquable The Ridens Rocky Shallows in the Center of the Channel A Distinguished Settlement Cahiers de Biologie Marine in French 29 1 93 107 Richesses de la mer Richness of the sea PDF in French Picardy Estuaries and Opal Sea Marine Natural Park Ridens et dunes hydrauliques du Pas de Calais in French Natura 2000 The Great Frost of 1683 4 www pastpresented info Retrieved 20 March 2020 Notes and Queries Notes and Queries Second Series 11 219 16 March 1861 via archive org The World of Wonders A Record of Things Wonderful in Nature Science and Art London Cassel Petter amp Galpin 1869 External linksChannel Navigation Information Service Channel Swimming amp Piloting Federation Channel Swimming Association Depth Chart showing straits and former course of Rhine
