Strait of Dover
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Map showing the location of the Strait of Dover. |
The
Strait of Dover or
Dover Strait (
French:
Pas de Calais,
IPA: , "Strait of
Calais",
Dutch:
Nauw van Kales) is the
strait at the narrowest part of the
English Channel. The shortest distance across the strait is from the
South Foreland, some 6
km (4
mi) north-east of
Dover in the county of
Kent,
England, to
Cap Gris Nez, a
cape near
Calais in the
département of
Pas-de-Calais,
France. Between these two points â€" the most popular route for cross-channel swimmers â€" the distance is just 33 km (20 mi).
The strait lies at the east end of the
English Channel, where it joins the
North Sea. Its width is the shortest distance between
France and
England. On a clear day, it is possible to see the opposite coastline and shoreline buildings with the naked eye.
Most maritime traffic between the
Atlantic Ocean and the
North and
Baltic Seas passes through the Strait of Dover, rather than take the longer and more dangerous route around the north of
Scotland. The Strait is one of the busiest international seaways in the world, regularly used by over 400 commercial vessels daily. This has made safety a critical issue, with
HM Coastguard maintaining a 24-hour watch over the strait and enforcing a strict regime of shipping lanes.
[See The Channel Navigation Information Service (CNIS)]In addition to the intensive east-west traffic, the Strait is criss-crossed from north to south by
ferries. Until the
1990s, these provided the only ground-based route for passengers and freight to cross it. The
Channel Tunnel now provides an alternative route, crossing underneath the Strait at an average depth of 45 m (150 ft) underneath the seabed.
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Satellite image of the Strait of Dover |
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NASA Satelite image September 2005 |
The Strait is believed to have been created through
erosion. At one time there was land where the Strait is now, being a southeast extension of the
Weald, joining what is now the island of
Great Britain to
continental Europe. The east end of this old longer Weald can be seen as the
Boulonnais chalk area in the
Pas de Calais. The predominant geology in the region on both the British and French sides and on the sea floor between to quite a depth into the
earth's crust is
chalk. Although somewhat resistant to erosion, such erosion of the chalk can be seen on both coasts as impressive sea
cliffs, the famous
White Cliffs of Dover, and
Cap Gris Nez on the French side of the Strait. This same rock also provided an excellent tunnelling medium for the
Channel Tunnel.
Originally the
Rhine flowed northwards into the North Sea as the sea level fell during the start of the first of the
Pleistocene Ice Ages. However, the ice created a
dam from
Scandinavia to
Scotland. 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 channel was gradually widened and deepened into the modern Strait of Dover. A narrow deeper channel along the middle of the Straits of Dover was the bed of the
Rhine in the last
Ice Age. In
East Anglia there is a geological deposit which marks the old
preglacial northward course of the
Rhine.
In general crossing the straits other than in a conventional vessel is not encouraged. Many such crossings have been attempted including by
pedalo,
bathtub and more commonly by
swimming. French law is stricter on such matters than UK law, so most such crossings originate in the UK.
Further information is available from the
Channel Navigation Information Service.
*
Battle of Dover Strait*
Channel Navigation Information Service*
Channel Swimming & Piloting Federation*
Channel Swimming Association
