Юралық жағалау: 185 миллион жылдық геологиялық тарих

World Heritage Site on the coast of southern England

The Jurassic Coast is a World Heritage Site on the English Channel coast of southern England. It stretches from Exmouth in East Devon to Studland Bay in Dorset, a distance of about 96 mile (154 km), and was inscribed on the World Heritage List in mid December 2001. The site spans 185 million years of geological history, coastal erosion having exposed an almost continuous sequence of rock formation covering the Triassic, Jurassic and Cretaceous periods. At different times, this area has been desert, shallow tropical sea and marsh, and the fossilised remains of the various creatures that lived here have been preserved in the rocks. Natural features seen on this stretch of coast include arches, pinnacles and stack rocks. In some places the sea has broken through resistant rocks to produce coves with restricted entrances and, in one place, the Isle of Portland is connected to the land by a barrier beach. In some parts of the coast, landslides are common. These have exposed a wide range of fossils, the different rock types each having its own typical fauna and flora, thus providing evidence of how animals and plants evolved in this region. The area around Lulworth Cove contains a fossil forest, and 71 different rock strata have been identified at Lyme Regis, each with its own species of ammonite. The fossil collector Mary Anning lived here and her major discoveries of marine reptiles and other fossils were made at a time when the study of palaeontology was just starting to develop. The Charmouth Heritage Coast Centre provides information on the heritage coast, and the whole length of the site can be visited via the South West Coast Path.

The Jurassic Coast consists of Triassic, Jurassic and Cretaceous cliffs, spanning the Mesozoic, documenting 185 million years of geological history. The site can be best viewed from the sea, when the dipping nature of the rock strata becomes apparent. In East Devon, the coastal cliffs consist of steep cliffs of red sandstone from the Triassic, and at Budleigh Salterton, the gravel cliffs contain red quartzite pebbles which accumulate on the beach below as Budleigh pebbles, locally protected. Further east at Ladram Bay, more sandstone cliffs give rise to spectacular red sandstone stacks. Around Lyme Regis and Charmouth the cliffs are of Jurassic clays and shale, and landslips are common. Chesil Beach is a good example of a barrier beach and stretches for 18 mile (29 km) from Burton Bradstock to the Isle of Portland. The beach encloses an intertidal lagoon which is an internationally important Ramsar Convention site known for its biodiversity. At Lulworth Cove, the waves have cut their way through the resistant Portland stone and created a horseshoe shaped cove by eroding the softer sands and clays behind. Another feature of this part of the coast is Durdle Door, a natural arch. Sea stacks and pinnacles, such as Old Harry Rocks at Handfast Point, have been formed by erosion of the chalk cliffs. The highest point on the Jurassic Coast, and on the entire south coast of Britain, is Golden Cap at 627 feet (191 m) between Bridport and Charmouth. This coast shows excellent examples of landforms, including the natural arch at Durdle Door, the cove and limestone folding at Lulworth Cove and a tied island, the Isle of Portland. Chesil Beach is a fine example of both a tombolo (a deposition landform in which an island is attached to the mainland by a narrow piece of land such as a spit or bar) and a storm beach (a beach affected by particularly fierce waves). The site has stretches of both concordant and discordant coastlines. Due to the quality of the varied geology, the site is the subject of international field studies. The many sedimentary layers on this coastline are rich with fossils, the remains of the animals and plants present in the area whose tissues became immersed in deposits of mud which later hardened into rock. At Lyme Regis, for example, geologists have identified 71 layers of rock, each one containing fossils of a different species of ammonite.

At the end of the 18th century Georges Cuvier showed that some fossil animals resembled no living ones, thus demonstrating that animals could become extinct; this led to the emergence of palaeontology, the study of fossils. The coasts of eastern Devon and western Dorset were rich in fossil beds, but before this time the fossils had merely been gathered as a pastime or collected by local residents and sold to visitors as curios. Mary Anning (1799–1847) lived in Lyme Regis and followed in her father's footsteps as a collector. She became an expert on the fossils to be found in the Blue Lias around the town and discovered the first complete Ichthyosaur skeleton at The Spittles. Other important discoveries of ichthyosaurs, plesiosaurs and a pterosaur followed, as well as invertebrates such as cephalopods and their ink sacs. During World War II several sections of the Jurassic Coast became the property of the Ministry of War. One of the Royal Navy's largest bases was at Portland Harbour, though it has since closed. A major army base at Bovington remains in use today. Large areas of land, including the coast between Lulworth Cove and Kimmeridge, are still only partially accessible; this includes the ghost village of Tyneham which was evacuated after being requisitioned by the army in 1943. Areas of the coast near Exmouth, The Fleet Lagoon at Weymouth and the beaches at Studland have also been used for military training but have since been returned to civilian use. Parts of the coast, especially around Portland, can be dangerous, and shipwrecks have been a feature of the coast. In January 2007 the coast experienced its most environmentally damaging wreck when the MSC Napoli, a 2,400 capacity container ship, was beached at Branscombe near Sidmouth, losing oil and cargo.

The Jurassic Coast is subject to severe weather conditions at times. Violent storms occurred in 1824 and 1974, and these and various lesser storms have battered the cliffs and caused flooding and structural damage in coastal towns. The coast is largely an eroding landscape and management of the site aims to allow the natural processes of erosion to continue while protecting people and property. Coastal defences have been put in place in Charmouth and Weymouth, where houses are at risk, but in other places, where the coastline remains in a natural state, the management policy is to take no action and allow erosion to take its course. The entire length of the coast can be walked on the South West Coast Path. Landslips and rockfalls are a continuing feature of the evolution of this coast. On 6 May 2008, a 1300 feet (396 m) section of the coast was dramatically re shaped after a landslip that was described as the worst in 100 years. There was a fatality in 2012 when of rock fell onto the beach at Burton Bradstock and another cliff fall took place in 2016 at West Bay, near Bridport. There was a further cliff collapse at Hive Beach near the village of Burton Bradstock shortly before dawn on 29 August 2020 after prolonged rain fall. The public were warned to stay clear of the unstable rocks. On 15 April 2021, a further collapse occurred. The collapse was described as being the biggest UK rockfall in 60 years.