The White Cliffs rise up to 110 metres above the sea on either side of Dover in Kent, at the narrowest point of the English Channel — around 21 miles from France, close enough to see the French coast on a clear day and to be seen from it.
What they are made of
Chalk, and chalk is biological. It formed on the floor of a warm shallow sea around 90 million years ago from the accumulated skeletons of coccolithophores — microscopic single-celled algae whose plates settled continuously to the sea bed.
The rate of accumulation was about half a millimetre a year, which means the full thickness of the Dover chalk represents tens of millions of years of sediment. The dark bands running through it are flint, formed from silica in the same deposits.
The cliffs are white because they are eroding. Wave action and frost strip the weathered surface away, exposing fresh chalk beneath — a cliff that stopped eroding would quickly become grey and vegetated. They retreat at roughly a centimetre a year on average, with occasional dramatic collapses.
The symbolism
For most of British history the Channel crossing was the only way in or out, and the cliffs were the first thing arrivals saw and the last thing departures watched disappear. That gave them a meaning no other landform in Britain has: home, and the edge of it.
They also read as a defensive wall, which is not entirely fanciful — the cliffs genuinely restrict landing places along that coast, and Dover has been fortified continuously since the Iron Age.
The song
(There’ll Be Bluebirds Over) The White Cliffs of Dover, recorded by Vera Lynn in 1942, fixed the association permanently. It was written by two Americans who had never seen the cliffs, and there are no bluebirds in Britain — but it became one of the defining songs of the war, and of the idea of coming home from it.
Vera Lynn’s death in 2020 at 103 was marked with a flypast and a projection of her image onto the cliffs.
The war beneath them
Dover was the front line. During the Second World War it was shelled directly from German guns on the French coast and became known as Hellfire Corner.
Inside the cliffs are the Secret Wartime Tunnels beneath Dover Castle — a warren originally dug during the Napoleonic wars and vastly extended, from which Operation Dynamo, the evacuation of Dunkirk, was directed by Vice-Admiral Ramsay in May 1940. They are open to the public and are among the more affecting historic sites in Britain.
Visiting
Most of the cliff top is owned by the National Trust, with a visitor centre and a clifftop path running to the South Foreland Lighthouse. The walk is exposed, spectacular and free.
The chalk grassland on top is a habitat in its own right, supporting orchids and rare butterflies, and peregrine falcons nest on the faces.
Stay well back from the edge. The chalk is unstable, undercut in places, and large sections have fallen without warning — including a substantial collapse in 2012.