The Jurassic Coast
The system of World Heritage Sites was created to protect treasures of nature, culture and beauty in 1972, after there had to be an international effort to save Egyptian temples from flooding by the Aswan High Dam.There are now 890 on the list. Countries submit candidate sites, and UNESCO (the United Nations Educational, Scientific and Cultural Organisation) approves them carefully.
A site can be struck from the list if it is not well looked after — a strong incentive to protection, because World Heritage status brings fame and tourism.Our coast was proposed by local people in 1993, and accepted in 2001. It’s the latest in the U.K.’s list of 17, and the only one that is a natural feature, rather than a human monument like Stonehenge or the Tower of London.
What is the Jurassic Coast?
This World Heritage Site is 95 miles long, from the Old Harry Rocks near Poole to the Exe estuary. Three-quarters of it is in Dorset and a quarter in Devon. Strictly, it is only a few hundred yards wide, from low-tide mark to the tops of the cliffs, and includes only natural environments — not town fronts and harbours.
Because the cliffline is notched by only a few valleys — most of them short and narrow — there are rather few towns and villages that touch the sea, such as Studland and Swanage, Lulworth and Osmington, Lyme Regis, Axmouth, Seaton, Beer, Sidmouth and Budleigh Salterton. West Bay now has a Jurassic Pier; Charmouth has an educational World Heritage Coast centre, and Weymouth will have one by the time it hosts the 2012 marine Olympics.
We can’t pretend that it isn’t English! Yet on more days than not it’s noticeable that there is open sky over this coast while cloud begins only a short way inland. People who drive down here talk of seeing a “slit of sunshine” over the sea ahead. And there really are sheltered spots, such as Abbotsbury, known for their almost tropical climates.
Why is this coast made of cliffs, and why are they so rich in fossils?
Draw a rough line across England from north Yorkshire to where Dorset and Devon meet. Everything southeast of this (“Lowland Britain”) is made of two thick layers.They were formed in the Jurassic and Cretaceous ages (from about 200 million to 65 million years ago). Mud and shells laid down on the sea floor hardened into rock (the Jurassic largely into limestone, the Cretaceous into greensand and chalk).Slow movements of the earth pushed them above water, and now they slope gradually up from the southeast to the northwest, where erosion has cut them off at long scarps (the Cotswolds and the Chilterns). It’s like a tilted plank lying on top of another tilted plank. We are at the southwestern end of these planks, where the sea has chewed them off. This is a simplified picture, but it makes the scenery much more interesting. If you look at the cliffs from the beach or from a boat, you can see layers that slope gently downward to the right.So the oldest and lowest layers are to the left — in Devon. They are from the Triassic period that came before the Jurassic. Then the Jurassic, slowly sloping down; then patches where the Cretaceous appears on top, as in Golden Cap. It was in the Triassic, Jurassic, and Cretaceous periods that dinosaurs flourished, and octopus-like sea creatures called ammonites. That’s why the spiral shells of ammonites, and bones of ichthyosaurs and plesiosaurs, are embedded in these rocks and are exposed as the sea attacks the cliffs.
Why not “Triassic Coast” or “Cretaceous Coast”?
Well, probably because everyone’s heard of “Jurassic Park”! There is a name, Mesozoic, that covers all three of those geological periods, but “Mesozoic Coast” just wouldn’t grab you, would it?