THE SITE

The World Heritage Site covers the 95 miles of cliffs and fore shore between Exmouth in East Devon and the southern end of Studland Bay in Dorset. The site does not include the frontages of the main towns, Exmouth, Budleigh Salterton, Sidmouth, Seaton, Lyme Regis, Weymouth and Swanage but these are the Gateways to the site.

There are six reasons why the coast has been designated a World Heritage Site.

1. The Rocks.

The cliffs and fore shore contain a near complete record through 185 million years of the Earth's history in just 95 miles of coast. This is the best place in the World to see a complete sequence of rocks from the Triassic, Jurassic and Cretaceous Periods of geological time.

The reason is simple: across the length of the coast, the overall dip of the rocks is gently to the east. As a result, the oldest rocks are found in the west but they dip down below the sea to the east, allowing progressively younger rocks to form the cliffs. Therefore, the oldest rocks from the Triassic period (250 to 200 million years old) form the red cliffs of East Devon. The dark clay rocks around Lyme Regis are the earliest Jurassic rocks (200 million years old) while the youngest form the Isle of Portland (140 million years old). In Purbeck, the distribution of the rocks is complicated by a huge fold that runs through Lulworth Cove and out to Ballard Down on the north side of Swanage Bay. Here the best sections through the Cretaceous rocks are exposed, including the Purbeck Beds and the Chalk.

There is a further complication in that during the Lower Cretaceous a period of erosion took place and therefore the overlying Upper Greensand lies on an eroded surface and there is a gap in the rock record known as an unconformity. Because the older rocks are tilted, the gap is more extreme to the west. In Swanage Bay, the unconformity is very small but in West Dorset, all of the Lower Cretaceous and most of the Jurassic rocks have been eroded away, while in East Devon, the Upper Greensand lies directly on the Triassic.

2. The Fossils.

There are a number of exceptional fossil sites along the coast including the Lower Jurassic rocks at Lyme Regis and the Fossil Forest on Portland and at Lulworth Cove.

The rocks and fossils tell a fascinating story from ancient deserts to a tropical sea packed with marine life and from a fossil forest to dinosaur infested swamps. The Triassic rocks of East Devon formed in a desert with huge rivers, rather like the Nile, flowing through them. At other times, vast lakes formed and they were subject to intense evaporation. The start of the Jurassic is marked around the world by a rapid rise in sea level. A tropical sea covered the area and it was packed with marine creatures, ammonites, (spiral shells) belemnites (the pencil shaped fossils), fish and ichthyosaurs. At the end of the Jurassic, sea levels dropped again and the newly formed rocks became land. A forest grew but soon drowned under a lagoon in which it became fossilised. Swamps and lagoons persisted in the early Cretaceous around which the dinosaurs roamed. Finally, sea levels rose again, allowing first sand and then the Chalk to form.

3. The Geomorphological (erosion) features.

The erosional features; the landslides of East Devon and West Dorset, Chesil Beach and the Fleet, the raised beaches of Portland and the Purbeck coastline including Durdle Door and Lulworth Cove and Old Harry Rocks near Studland are superb examples of their type.

3. The History of Science

The coast has been the subject of geological sciences for the last 250 years. Indeed, a very considerable part of the early thinking about the nature of the Earth, geological time and the evolution of life was informed from this coastline. The people who visited read like a whos who of geological scientists. In Lyme Regis the list includes Sir Henry De la Beche (1796-1855) the first Director of the British Geological Survey, the Reverend William Conybere (1787-1857) and William Buckland (1784-1856) from Oxford University and Mary Anning, (1799 1846), perhaps the most famous fossil collector of all time.

5. Research and Education

Today, the coast remains the subject of ongoing research. Fossils new to science continue to be found virtually every year. New thinking about landslides and the formation of Chesil Beach is currently being developed, especially in relation to the coast defence of Lyme Regis and West Bay. The rocks also represent one of the best cross sections through an oil field anywhere. Thousands of people come here to learn about geology.

6. A beautiful coastline

The changing geology and the erosion cutting into the rocks has created a coastline of great diversity and beauty.