Purbeck, Isle of, peninsula, c.12 mi (20 km) long and c.8 mi (13 km) wide, Dorset, S England, between Poole Harbour and the English Channel. St. Albans Head is the most southerly point of the rocky shore. Ranges of chalk hills cross the peninsula from east to west. The region is noted for the production of Purbeck marble and china clay. Purbeck was a favorite hunting ground of Saxon and Norman kings. The larger district of Purbeck was named after this peninsula.