The white cliffs of Dover are cliffs which form part of the British coastline facing the Strait of Dover an France. The cliffs are part of the North Downs formation. The cliff face, which reaches up to 350 feet high, owes its striking façade to its composition of chalk (pure white calcium carbonate) accentuated by streaks of black flint. The cliffs spread east and west from the town of Dover in the county of Kent, an ancient and still important English port.