<P> The cliffs are located along the coastline of England between approximately 51 ° 06 ′ N 1 ° 14 ′ E ﻿ / ﻿ 51.100 ° N 1.233 ° E ﻿ / 51.100; 1.233 and 51 ° 12 ′ N 1 ° 24 ′ E ﻿ / ﻿ 51.200 ° N 1.400 ° E ﻿ / 51.200; 1.400.It marks the point where Great Britain most closely approaches continental Europe and on a clear day the cliffs are easily visible from the French coast . The chalk cliffs of the Alabaster Coast of Normandy, France, are part of the same geological system as Dover's cliffs . </P> <P> The cliffs have great symbolic value in Britain because they face towards continental Europe across the narrowest part of the English Channel, where invasions have historically threatened and against which the cliffs form a symbolic guard . The National Trust calls the cliffs "an icon of Britain", with "the white chalk face a symbol of home and war time defence ." Because crossing at Dover was the primary route to the continent before the advent of air travel, the white line of cliffs also formed the first or last sight of Britain for travellers . In World War II, thousands of allied troops on the little ships in the Dunkirk evacuation saw the welcoming sight of the cliffs . During the summer of 1940, reporters gathered at Shakespeare Cliff to watch aerial dogfights between German and British aircraft during the Battle of Britain. l </P> <P> The White Cliffs are at one end of the Kent Downs designated Area of Outstanding Natural Beauty . In 1999 a sustainable National Trust visitor centre was built in the area . The Gateway building was designed by van Heyningen and Haward Architects and houses a restaurant, an information centre on the work of the National Trust, and details of local archaeology, history and landscape . </P> <P> Around seventy million years ago Great Britain and much of Europe was submerged under a great sea . The sea bottom was made of a white mud formed from fragments of coccoliths, the skeletons of tiny algae which floated in the surface waters of the sea and then 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 only half a millimetre a year, equivalent to about 180 coccoliths piled one on top of another . Still, up to 500 metres of sediments were deposited in some areas . Through the weight of overlying sediments, the deposits eventually became consolidated into chalk . </P>

What is the origin of the chalk cliffs in dover england