Posted by: dorsetcpre | March 1, 2011

Walking the Jurassic Coast

The East Devon and Dorset World Heritage Site, popularly known as The Jurassic Coast, is England’s first natural World Heritage Site. It was nominated by UNESCO in December 2001 for its unique insight into the earth sciences and this year marks the tenth anniversary of the nomination. These sedimentary rocks which were formed between 250 and 65 million years ago record 185 million years of the Earth’s history. They create a walk through time that includes the Triassic, Jurassic and Cretaceous periods.

Fossils at Charton BayDuring the summer of 2010 on fourteen consecutive Saturdays I completed a guided walk, of about 95 miles, along the whole of the World Heritage Site. The walk began at Exmouth and ended at Studland. We studied the geology and erosion processes along the coast together with the formation and the extraction of a variety of minerals.

We were generally a fairly small group of between six and nineteen persons and had a different local guide for each walk, sometimes a geologist, sometimes a quarryman or a warden from the National Trust. This worked well as they described a variety of different aspects of the coast and the adjacent countryside. I shall try to describe some of the highlights of this walk but there was so much to see that I shall not have space for everything of interest.

We started the walk at the Geoneedle (an obelisk showing some of the types of stone found on the Coast) at Orcombe Point on the outskirts of Exmouth. The wind was blowing hard and we had several heavy showers but this was the only wet day during the whole walk. The east Devon coast, sometimes called the Triassic Coast, has a series of dramatic red cliffs which were laid down 250 million years ago in desert conditions. The Budleigh Salterton Pebble Beds were transported here by a giant river flowing from the south in Triassic times.

Ladram Bay has a popular beach with several spectacular sea stacks just a few yards offshore, and then we had a couple of steep climbs to High Peak and Peak Hill.

The Hooken landslide, which occurred in 1789-90, is a jumbled mass of rocks with a narrow footpath winding its way through. An isolated white cliff of chalk stands out at Beer and this hard chalk has been quarried for many years at Beer Caves for high quality masonry work.

The Undercliffs National Nature Reserve between Axmouth and Lyme Regis is a series of landslides about five miles long and is one of the most important wilderness areas in the Country. This was a splendid walk. We climbed up over Goat Island and looked down into The Chasm which was formed by the famous landslide on Christmas Eve in 1839.

The lower part of Lyme Regis town was built on a series of landslips which are still active. A major programme of works in the last few years will help to stabilise the buildings of the town. Mary Anning was the first to find some important fossils here, many more have be found since and are still being found.

The exposure of Jurassic rocks, laid down about 200 million years ago, begins at Charmouth where there is an Information Centre and a fossil shop. This is a very good place to find fossils on the beach. We passed by more landslips and after two more steep climbs reached Golden Cap. This is the highest point on the south coast of England with glorious views both ways along the coast. The harbour at West Bay used to be repeatedly damaged by storms rolling in from the Atlantic. It has now been completely rebuilt with extensive rock armour to protect it. Burton Cliff, just east of West Bay, is composed of yellow Bridport sand and dominates a wide popular beach.

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Further east the Fleet, sitting behind Chesil Beach, is the largest tidal lagoon in the country with a great variety of wading birds and other wildlife. We visited the swannery at Abbotsbury where they have managed the swans since the fourteenth century and then walked, on level ground for a change, all along the side of the Fleet.

Chesil Beach stretches eighteen miles from West Bay increasing in size until it is fifteen metres high and eight hundred metres wide at Chiswell. The village used to be flooded from time to time but a highly effective flood management scheme has been built. This depends on a large culvert which collects the water that percolates through the beach and discharges it into Portland Harbour.

The Isle of Portland is a huge block of limestone which has been quarried since Roman times (see Dorset Review 91, Autumn 2008, 13). We started high above the sea at The Verne Prison and descended in easy stages to a wide open green space at the Coastal Strip which may soon be taken over for further quarrying (Dorset Review 92, Spring 2009, 10). We visited the three lighthouses and the raised beaches at Portland Bill and then walked up the West Wears to Tout Quarry where there is a collection of open air sculptures.

The National Sailing Academy at Portland Harbour will host the Olympic sailing events next year. Sandsfoot Castle on the outskirts of Weymouth is presently in ruins but will shortly be refurbished and opened to the public. The new sea defences at Preston mean that the road no longer has to be closed several times a year when it gets covered with beach pebbles. We then climbed to White Nothe, a massive chalk cliff which was laid down during the Cretaceous period about 100 million years ago, and walked up and down a series of chalk cliffs to Bats Head.

Lulworth Cove which forms a perfect horseshoe, the Lulworth Crumple at Stair Hole, and Durdle Door are textbook examples of coastal erosion which attract many visiting school and university students. This is probably the finest scenery and the most important geology on the south coast and, arguably, some of the best in the country.

The next section is used by the Army but the Range Walks are open during the school holidays and most weekends throughout the year. We admired the trees in the fossil forest on a remote ledge high above the sea. Flowers barrow, on the top of the cliff at Worbarrow Bay, is a hill fort which was built in the Iron Age but about half of it has fallen into the sea over the past 2500 years as a result of coastal erosion. Gad Cliff which dominates the view of this part of the coast consists mainly of limestone but the slopes of the undercliff are inaccessible. There are several steep climbs here and this is quite the most strenuous part of the Coastal Path. The village of Tyneham, deserted since 1943 when the Army used the area for training during the War, has a church, a school room and several cottages open to the public.

We then dropped down to Kimmeridge where the Marine Wildlife Reserve is run by the Dorset Wildlife Trust. We passed one or two working quarries and many more which had been worked out. Further on, we looked at St Aldhelm’s chapel, Anvil Point lighthouse, Durlston Country Park and then the Victorian Durlston Castle which is presently being refurbished to provide a visitor centre for the eastern end of the World Heritage Site. We walked past Swanage and across the top of the chalk hills (late Cretaceous period, 65 million years ago) of Ballard Down past Old Harry and the other sea stacks to the end of the World Heritage Site at Redend Point .

I have only had room to describe a small fraction of the many, many sites of interest along this walk but it was a thoroughly enjoyable experience and I have been told that a similar series of walks will be available again this year. If you are interested in doing one, or more, of the stages then visit www.jurassiccoast.org where you will also find other events along the coast throughout the year.

Dr John Larkin
Minerals and Waste Adviser

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