Located on the World famous Jurassic heritage coast, Durdle Door is a stunning, naturally formed limestone arch. The arch is on privately owned land, located near Lulworth, but it is open to the public, The name "durdle" comes from the old English "Thirl" which means bore or drill.
The geology making up the arch is composed of almost vertical bands of narrow limestone rock, which runs parallel to the chalk of the coast line. The arch formed as a result of the softer rock behind the limestone being eroded away (through joints in the limestone itself), and eventually the sea managed to punch through the limestone, leaving the archway. Eventually the arch will collapse, leaving sea stacks behind similar to those that can be seen all along the South West Coast.
The Bull, a rock sticking out from the sea, close to Durdle Door is a continuation of the rock strata found in the arch.
Image; Saffron Blaze