White cliffs of Dover
From Free net encyclopedia
Image:White cliffs of dover 09 2004.jpg The white cliffs of Dover, immortalized in popular song and verse (by Vera Lynn, Kate Smith, Matthew Arnold, Eric Johnson and others), are cliffs facing the Strait of Dover near the major English port town of Dover, in the county of Kent, and form part of the North Downs. The cliff face, which reaches up to 350 feet high, owes its striking façade to its composition of chalk (pure white lime) accentuated by streaks of black flint.
The cliffs are located along the coastline between approximately: Latitude 51°06'N, Longitude 1°14'E and Latitude 51°12'N, Longitude 1°24'E.
The cliffs are composed mainly of coccoliths and trace their origins to the Cretaceous Period, approximately 136 million years ago, when the area between Britain in the west and Sweden/Poland in the east was submerged under deep tropical waters. Subjected to the great pressures of the sea, the emptied skeletons of coral, sponges and other small sea creatures turned to sediment and began to accumulate on the ocean floor. By approximately 70 million years ago, this process had formed a mass of silica-specked chalk covering huge areas between Britain and the Baltic Sea — white cliffs like those of Dover (but smaller) are also found on the Danish islands of Mon and Langeland or the coasts of the island of Rügen in Germany. The chalk layer used to lay high above sea level during the ice ages and in many places additionally was covered with glaciers. After the ice ages, they were exposed to the rising sea. Owing to the exceptional softness of chalk, tidal forces have since then significantly eroded this land mass away, in Dover to form the English Channel.
Image:Cliffs of Dover erosion.jpg Image:White Cliffs of Dover map.png
The cliff face continues to erode at an average rate of one centimeter per year, although occasionally—most recently in 2001—large chunks of the edge, up to several meters at once, will fall into the channel with little warning. Visitors are therefore urged to remain at least five metres back from the edge.
Behind the cliff face are miles of hidden tunnels that were created during the Middle Ages and later played a role in the defense of Britain during the Napoleonic Wars. The tunnels were later enlarged to become the Secret Wartime Tunnels beneath Dover castle.
Shakespeare Cliff marks the point where England most closely approaches continental Europe.
Many different kinds of birds nest on the cliff face, including peregrine falcon and colonies of kittiwake.
In a 2005 poll of Radio Times readers, the cliffs were named as the 3rd greatest natural wonder in Britain.