Dorset has a varied landscape featuring broad elevated chalk downs, steep limestone ridges and low-lying clay valleys. Over half the county is designated as an Area of Outstanding Natural Beauty. Three-quarters of its coastline is part of the Jurassic Coast Natural World Heritage Site due to its geological and palaeontologic significance. It features notable landforms such as Lulworth Cove, the Isle of Portland, Chesil Beach and Durdle Door. Agriculture was traditionally the major industry of Dorset but is now in decline and tourism has become increasingly important to the economy. There are no motorways in Dorset but a network of A roads cross the county and two railway main lines connect to London. Dorset has ports at Poole, Weymouth and Portland, and an international airport near Bournemouth. The county has a variety of museums, theatres and festivals, and is host to the Great Dorset Steam Fair, one of the biggest events of its kind in Europe. It is the birthplace of Thomas Hardy, who used the county as the principal setting of his novels, and William Barnes, whose poetry celebrates the ancient Dorset dialect.