White Cliffs of Dover

Extent of the White Cliffs of Dover

White Cliffs of Dover, seen from France

The cliffs are part of the coastline of Kent in England between approximately 51°06′N 1°14′E and 51°12′N 1°24′E, at the point where Great Britain is closest to continental Europe. On a clear day they are visible from the French coast. The chalk cliffs of the Alabaster Coast of Normandy in France are part of the same geological system.

The White Cliffs are at one end of the Kent Downs designated Area of Outstanding Natural Beauty.[4] In 1999 a sustainable National Trust visitor centre was built in the area. The Gateway building, designed by van Heyningen and Haward Architects, houses a restaurant, an information centre on the work of the National Trust, and details of local archaeology, history and landscape.[5]

About 70 million years ago Great Britain and much of Europe were submerged under a great sea. The sea bottom was covered with white mud formed from fragments of coccoliths, the skeletons of tiny algae that floated in the surface waters and sank to the bottom during the Cretaceous period and, together with the remains of bottom-living creatures, formed muddy sediments. It is thought that the sediments were deposited very slowly, probably half a millimetre a year, equivalent to about 180 coccoliths piled one on top of another. Up to 500 metres of sediments were deposited in some areas.[6] The weight of overlying sediments caused the deposits to become consolidated into chalk.[7]

The cliffs' multiple layers of flint match those seen across the channel at Cap Gris Nez, France, evidence of a land connection between England and France in prehistoric times.

Subsequent earth movements related to the formation of the Alps raised the sea-floor deposits above sea level. Until the end of the last glacial period, the British Isles were part of continental Europe, linked by the unbroken Weald-Artois Anticline, a ridge that acted as a natural dam to hold back a large freshwater pro-glacial lake, now submerged under the North Sea. The land masses remained connected until between 450,000 and 180,000  years ago when at least two catastrophic glacial lake outburst floods breached the anticline and destroyed the ridge that connected Britain to Europe. A land connection across the southern North Sea existed intermittently at later times when periods of glaciation resulted in lower sea levels.[8] At the end of the last glacial period, around 10,000 years ago, rising sea levels finally severed the last land connection.[9]

The cliffs' chalk face shows horizontal bands of dark-coloured flint which is composed of the remains of sea sponges and siliceous planktonic micro-organisms that hardened into the microscopic quartz crystals. Quartz silica filled cavities left by dead marine creatures which are found as flint fossils, especially the internal moulds of Micraster echinoids. Several different ocean floor species such as brachiopods, bivalves, crinoids, and sponges can be found in the chalk deposits, as can sharks' teeth.[10]

In some areas, layers of soft, grey chalk known as a hardground complex can be seen. Hardgrounds are thought to reflect disruptions in the steady accumulation of sediment when sedimentation ceased and/or the loose surface sediments were stripped away by currents or slumping, exposing the older hardened chalk sediment. A single hardground may have been exhumed 16 or more times before the sediments were compacted and hardened (lithified) to form chalk.[10]

Erosion and the effects of climate change

Evidence of erosion along the cliff top

The White Cliffs of Dover have been eroding slowly but in the past 150 years they have been eroding ten times faster than they did before.[11] This is because of the thinning of beaches that separate the cliffs from the sea and the fact that the cliffs themselves are made up of coccolithophore shells, which are chalk-based and unusual in forming calcium carbonate shells which eventually sink to the seabed to form chalky deposits that are vulnerable to erosion.[12] The change is likely due to the construction of sea walls and groynes, and stronger storms hitting the coastline due to climate change and the rise of CO
2 in the ocean.[11] Scientists say that the English Channel has eaten away at the cliffs at a rate of 8.7 inches to just over a foot. A thousand years ago, that rate was three-quarters of an inch to 2.3 inches per year.[11]

Landslide near Dover Harbour, June 2012

Over the years, the cliffs began to crumble as well and there have been sudden cliff falls due to the erosion of the chalk.[13] In 2001, a large chunk of the cliff edge, as large as a football pitch, fell into the Channel.[14] Another large section collapsed on 15 March 2012.[15] As mentioned before, coccolithophores shells have increased in the ocean due to the increase of carbon dioxide in the sea. The ocean absorbs CO
2 and while that happens the pH drops and the water becomes more acidic. One of the forms affected by this is a type of phytoplankton called coccolithophores. Ocean acidification can damage corals, such as those in the Great Barrier Reef. This can affect the coral strength and lead to them breaking more easily and more often. Coccolithophores make up the White Cliffs of Dover, and because of ocean acidification, it is causing them to erode at a faster rate.[16][11][17] All together, this could affect the wildlife on the cliffs and the cliffs themselves, for if they continue to erode, they could disappear altogether.[11][17][18][13][16]

The White Cliffs are eroding because of the rise of sea levels and the decrease of pH levels in the ocean due to the rise of CO
2 in the ocean.[19] The only way this can be solved is if the beaches that separate the cliffs from the ocean are well maintained and the cliffs themselves are cared for.[17] If the level of CO
2 in the ocean continues to rise, then the eroding of the cliffs will continue to increase in the years to come.

Exmoor ponies in their native habitat

The chalk grassland environment above the cliffs provides an excellent environment for many species of wild flowers, butterflies and birds, and has been designated a Special Area of Conservation and a Site of Special Scientific Interest. Rangers and volunteers work to clear invasive plants that threaten the native flora. A grazing programme involving Exmoor ponies has been established to help to clear faster-growing invasive plants, allowing smaller, less robust native plants to survive.[20] The ponies are managed by the National Trust, Natural England, and County Wildlife Trusts to maintain vegetation on nature reserves.[21]

Peregrine falcon off White Cliffs, Dover

The cliffs are the first landing point for many migratory birds flying inland from across the English Channel. After a 120-year absence, in 2009 it was reported that ravens had returned to the cliffs. Similar in appearance but smaller, the jackdaw is abundant. The rarest of the birds that live along the cliffs is the peregrine falcon. In recent decline and endangered, the skylark also makes its home on the cliffs.[22] The cliffs are home to fulmars, which resemble gulls, and to colonies of black-legged kittiwake, a species of gull. Bluebird, as mentioned in the classic World War II song "(There'll Be Bluebirds Over) The White Cliffs of Dover" is an old country name for swallows and house martins, which make an annual migration to continental Europe, many of them crossing the English Channel at least twice a year.

Among the wildflowers are several varieties of orchids, the rarest of which is the early spider orchid, which has yellow-green to brownish green petals and looks like the body of a large spider. The oxtongue broomrape is an unusual plant that lives on the roots of a host plant. It has yellow, white, or blue snapdragon-like flowers and about 90 per cent of the UK's population is found on the cliffs. Viper's-bugloss, a showy plant in vivid shades of blue and purple with red stamens, also grows along the cliffs.[22] In his play King Lear, Shakespeare mentions rock samphire, an edible plant that grows on the cliffs. It was collected by gatherers who hung from ropes down the cliff: "Half-way down / Hangs one that gathers samphire; dreadful trade!" (Act IV, Scene VI). This refers to the dangers involved in collecting rock samphire on sea cliffs.

The abundance of wildflowers provides homes for about thirty species of butterfly. The rare Adonis blue can be seen in spring and again in autumn. Males have vibrant blue wings lined with a white margin, whereas the females are a rich chocolate brown. This species' sole larval food plant is the horseshoe vetch and it has a symbiotic relationship with red or black ants. The eggs are laid singly on very small foodplants growing in short turf. This provides a warm microclimate, suitable for larval development, which is also favoured by ants. The caterpillar has green and yellow stripes to provide camouflage while it feeds on vetch. The ants milk the sugary secretions from the larval "honey glands" and, in return, protect the larvae from predators and parasitoids, even going so far as to bury them at night. The larvae pupate in the upper soil, and continue to be protected by the ants, often in their nests, until the adults emerge in the spring or autumn.[23]

Chalk hill blue, male on left female on right

Similar in appearance, but more abundant, is the chalk hill blue, a chalk grassland specialist that can be seen in July and August.[24][22] Threatened species include the silver spotted skipper and straw belle moth. The well-known red admiral can be seen from February until November. The marbled white, black and white with a white wing border, can be seen from June to August.

Samphire Hoe Country Park

Samphire Hoe Country Park with local railway and tunnel (not the Channel Tunnel which is nearby).

Samphire Hoe Country Park is a nature reserve on a new piece of land created from the rock excavated during the construction of the Channel Tunnel. It covers a 74-acre (30 ha) site at the foot of Shakespeare Cliff, between Dover and Folkestone. There is an education shelter with a classroom and exhibition area. Staff and volunteers are available to answer questions and provide information about the wildlife in the reserve. The building's design incorporates eco-construction criteria. Samphire, a wild edible plant, grew on the cliffs and was gathered by hanging from ropes over the cliff's edge. Shakespeare Cliff was named after the reference to this "dreadful trade" in Shakespeare's play King Lear (Act 4, Scene 6, Lines 14-15).

The Roman lighthouse at Dover Castle.

A possible Iron Age hillfort has been discovered at Dover, on the site of the later castle.[25] The area was also inhabited during the Roman period, when Dover was used as a port. A lighthouse survives from this era, one of a pair at Dover which helped shipping navigate the port. It is likely the area around the surviving lighthouse was inhabited in the early medieval period as archaeologists have found a Saxon cemetery here, and the church of St Mary in Castro was built next to the lighthouse in the 10th or 11th century.[26] It is thought that the Old English name for Britain, Albion, was derived from the latin albus (meaning 'white') as an allusion to the white cliffs.[27]

Dover castle

The castle, Dover, England, with White Cliffs in foreground - circa 1890 to 1900

Dover Castle, the largest castle in England,[28] was founded in the 11th century. It has been described as the "Key to England" owing to its defensive significance throughout history.[29][30] The castle was founded by William the Conqueror in 1066 and rebuilt for Henry II, King John, and Henry III. This expanded the castle to its current size, taking its curtain walls to the edge of the cliffs. During the First Barons' War the castle was held by King John's soldiers and besieged by the French between May 1216 and May 1217. The castle was also besieged in 1265 during the Second Barons' War. In the 16th century, cannons were installed at the castle, but it became less important militarily as Henry VIII had built artillery forts along the coast. Dover Castle was captured in 1642 during the Civil War when the townspeople climbed the cliffs and surprised the royalist garrison, giving a symbolic victory against royal control. Towards the end of the war many castles were slighted, but Dover was spared.[31]

The castle had renewed importance from the 1740s as the development of heavy artillery made capturing ports an important part of warfare. During the Napoleonic Wars, in particular, the defences were remodelled and a series of tunnels were dug into the cliff to act as barracks, adding space for an extra 2,000 soldiers. The tunnels mostly lay abandoned until the Second World War.[32]

South Foreland Lighthouse

South Foreland lighthouse

South Foreland Lighthouse is a Victorian-era lighthouse on the South Foreland in St. Margaret's Bay, which was once used to warn ships approaching the nearby Goodwin Sands. Goodwin Sands is a 10-mile-long (16 km) sandbank at the southern end of the North Sea lying six miles (10 km) off the Deal coast. The area consists of a layer of fine sand approximately 82 ft (25 m) deep resting on a chalk platform belonging to the same geological feature that incorporates the White Cliffs of Dover. More than 2,000 ships are believed to have been wrecked on the Goodwin Sands because they lie close to the major shipping lanes through the Straits of Dover. It went out of service in 1988 and is now owned by the National Trust for Places of Historic Interest or Natural Beauty.

• The most famous reference in English literature to the White Cliffs is in Shakespeare's King Lear. In Act IV, Scene VI, Edgar persuades the blinded Earl of Gloucester that he is at the edge of a cliff at Dover. In Act IV, Scene I, Lines 72-4, Gloucester says, "There is a cliff, whose high and bending head looks fearfully in the confinèd deep: Bring me but to the very brim of it." Edgar then fools the Gloucester into thinking he is at the cliff edge and describes the scene: "Here's the place! – stand still – how fearful/ And dizzy 'tis, to cast one's eye so low ... half way down/Hangs one that gathers samphire: dreadful trade!/Methinks he seems no bigger than his head." (Act IV, Scene VI, Lines 11-16).[38]

Wikisource has original text related to this article: 'The Cliffs of Dover' by Felicia Hemans.

• In 1851, English poet Matthew Arnold began his lyric poem Dover Beach by epitomizing the beauty of the Kent coast:

The sea is calm tonight,

The tide is full, the moon lies fair

Upon the straits:- on the French coast, the light

Gleams, and is gone: the cliffs of England stand,

Glimmering and vast, out in the tranquil bay.[38]

• The verse novel The White Cliffs by Alice Duer Miller encouraged U.S. entry into World War II.

• The White Cliffs have long been a landmark for sailors. It is noted as such in the sea shanty Spanish Ladies:[39]

"The first land we sighted was called the Dodman,

Next Rame Head off Plymouth, off Portsmouth the Wight;

We sailed by Beachy, by Fairlight and Dover,

And then we bore up for the South Foreland light."

• On a Piece of Chalk was a lecture by Thomas Henry Huxley presented to the British Association for the Advancement of Science in 1868 and published later that year.[40] The piece reconstructs the geological history of Great Britain from a simple piece of chalk and demonstrates science as "organized common sense".[41]

Also referenced as the title of "Cliffs of Dover" by musician Eric Johnson

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  Shakespeare Cliff, Dover ca. 1905
• 
  Lighthouse in Dover
• 
  Dover Castle
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  White Cliffs of Dover footpath
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  Folkestone and Dover from the International Space Station, showing the White Cliffs and the tracks of ferries.
• 
  Vintage photo taken by Walter Mittelholzer, Swiss photographer and aviator, 1933.

Wikimedia Commons has media related to White Cliffs of Dover.

• Aerial view of the cliffs and surrounding area on YouTube
• Dover Museum information on the cliffs
• White Cliffs of Dover website