Environment, Natural History, Natural Patterns Stair Hole, Lulworth Image 9 June 2016 Ian Alexander Stair Hole, Lulworth. Soft Wealden Sands (foreground) overlie crumpled Liassic clays and marls (left) which in turn overlie hard Jurassic rocks of Purbeck and Portland limestone (dark rocks, centre). (Click to enlarge)