Flints in the chalk cliffs at Ovingdeal, Sussex

Lines of flints embedded in the White Chalk cliffs between Ovingdean and Rottingdean in East Sussex. The cliffs tower up to 30 m. in height above the sea at high water, dwarfing even a seven-storey block of flats at Rottingdean.
The chalk is formed of the fossilised remains of small molluscs and microscopic marine algae which accumulated at the bottom of the sea in the late Cretaceous period.
The Ovingdean Cliffs include layers of solid flint material as well as the flint nodules so typical of Sussex architecture. Flints are rock which has been hardened by a chemical change; flints contain fossils, including marine coral or leafy materials. Despite their ubiquity in Sussex and Kent, the geological origin of flints is still disputed.
The concrete at the foot of the cliffs, part of the Undercliff Walkway, is the latest attempt to reduce erosion from the sea.