White Cliffs of Dover
The White Cliffs of Dover are among the most iconic natural features in Britain, a wall of bright white chalk rising up to 110 metres above the English Channel at the narrowest point of the strait that separates England from mainland Europe. Their significance in national consciousness derives partly from their geological drama and partly from their role as the first sight of England for travellers arriving by sea from the continent, a function they have served for travellers, refugees, traders, armies and returning residents throughout recorded history. The cliffs are composed of chalk laid down during the Cretaceous period approximately 65 to 100 million years ago, when the area now occupied by the English Channel was a warm, shallow sea. The accumulated remains of countless billions of microscopic marine organisms settled on the seabed and were compressed over geological time into the dense, white calcium carbonate rock visible in the cliff faces. The characteristic dark lines of flint nodules running through the chalk faces are formed from the siliceous remains of sponges, concentrated and consolidated along bedding planes as the chalk was buried and compressed. The seven-mile stretch of cliffs managed by the National Trust between Langdon Cliffs near the town of Dover and St Margaret's Bay provides the best walking access to the cliff edge, with dramatic views across the Channel to the French coast on clear days. The distance from the English coast to France is just 33 kilometres at its narrowest, and the chalk cliffs of Cap Blanc-Nez are clearly visible on the French side, a geological continuation of the same chalk formation interrupted by the Channel valley cut during the last Ice Age. The wartime history of the cliffs and the tunnels beneath Dover Castle, used as military headquarters during both World Wars, adds a layer of historical significance to the landscape's natural drama.