White Cliffs of Dover

The White Cliffs of Dover are a stretch of chalk cliffs on the English Channel coast of Kent, England, facing France across the Strait of Dover, formed from a thick layer of soft white limestone known as the Cretaceous Chalk Group, laid down between about 100 and 66 million years ago from the accumulated calcareous remains of countless microscopic marine organisms called coccolithophores. The chalk formed on the floor of a warm, shallow sea, and later tectonic uplift raised the deposit above sea level, where erosion by wave action along the coastline exposed the near-vertical white cliff faces, which reach heights of about 110 meters. Bands of dark flint nodules run through the chalk, and the cliffs' visibility from continental Europe on clear days has long made them a symbolic first or last sight of England, and a significant unit in the wider Chalk Group that also underlies much of southeastern England and the Paris Basin.