Collapsing limestone wave-cut platform. As the shale is eroded away limestone blocks collapse off the platform. This Langport blue lias formation was laid down in shallow seas 183-204 million years ago in the Jurassic and Triassic periods. After the deposits were formed stresses created the joints (fine cracks) in the limestone which have been widened by wave action. Alternate layers of soft mudstone shale and harder limestone are in horizontal beds which the sea has scoured away leaving a cliff and a flattish wave cut platform. Four limestone beds are revealed and the one in the foreground has still got shallow joints. Photographed at Lilstock, Somerset, UK.