The Jurassic Coast is a 155 km (95 mile) stretch of the British coastline between Exmouth in Devon and Old Harry Rocks in Dorset. A designated World Heritage Site, the Jurassic Coast is internationally known for its archaeological and geological importance, due to its rocks, fossils and landforms. The coastline varies rather greatly, including cliffs, headlands, archways and coves, but also sandy beaches, a large lagoon and even a rare phenomenon known as a tied island. There are also several picturesque port towns along the coastline, including Sidmouth, Lyme Regis and Swanage. I think it is fair to say that this is one of the most important and interesting stretches of coastline in the United Kingdom.
Paleontological Importance
The reason for the name ‘Jurassic Coast’ is due to – as you may have already assumed – its strong association with this geologic period. It is described by the Jurassic Coast Trust as ‘a key locality for the development of palaeontology’ – in other words, this coastline has provided scientists and researchers with a vast array of artifacts and evidence that have shaped paleontological science [1]. This is because the Jurassic Coast not only consists of rocks formed during this time, but also of many fossils of ancient creatures and flora from this period. This has included (though is not limited to) our knowledge of dinosaur species – for example, an ichthyosaur skull was found in rocks near Lyme Regis in Dorset. There have been many other discoveries as well as this, and a vast number of fossils are on display to the public, in various museums and visitor centres along the Jurassic Coast [1]. One example of these museums is in Lyme Regis – simply named ‘Lyme Regis Museum’, this exhibition includes an interactive geology gallery, and information about fossil hunting walks and the history behind the discovery of fossils [2].
Cliffs and Rock Type
The coast itself consists of many features typical of the British coastline, particularly in south-western England. Most notable are the cliffs – these are formed from sedimentary rocks, most notably limestone, shale and mudstone, although sandstone and chalk outcrops exist as well. The cliffs are mostly, as you may have guessed, Jurassic in age; however, it is worth noting that the cliffs to the west of Lyme Regis are mainly Triassic [3]. Either way, these cliffs are wholly sedimentary, which is perfect for preserving fossils. This is because, when sediment and organic material are deposited at the same time, any bones or other organic material deposited in the sediment is preserved. The cliffs themselves often vary in height, and are often intercepted with valleys that contain beaches and sometimes a seaside town or village. The coastline can also be rugged in various places, with various geological features that are significant for their fairly unusual nature in Great Britain. It is also worth noting that these cliffs are quite erosive; on one hand, land is lost to the waves quite frequently along this coastline, but on the other hand, fossils are exposed with every small section of cliff that collapses.
Headlands and Arches
Erosion along the coastline leads to interesting phenomena. One is the existence of headlands; there are several headlands along this stretch of coastline, including the Durdle Door headland and Handfast Point. Marking the most eastern extent of the Jurassic Coast, Handfast Point is a headland that points eastwards into the English Channel; at the end of this headland exists Old Harry Rocks. These rocks are remnants of a headland that once reached out much further into the sea, but has since been severely eroded by the sea, leaving only a couple of rock stacks and a rock stump behind. Another feature along the coast is Durdle Door. Although this name technically only relates to the natural arch at the end of the headland, it is worth mentioning that this is the result of the usual erosion of headlands: first the headland is eroded from both sides perpendicular to the headland, allowing an arch to be formed, and over time this arch is weakened and then collapses. Durdle Door is currently at the natural arch phase of this process – eventually, due to erosion and pounding from waves, the arch will collapse, leaving a rock stack cut off from the mainland. This particular feature is a very popular tourist destination, particularly due to the archway being regarded as an iconic landmark of the British landscape. It also has a very pleasant beach, which is often packed with tourists during the summer months.
Coves
There are other erosion-related features along this coastline. Located 15km (10 miles) to the east of Weymouth, Lulworth Cove is a postcard-like formation along the Dorset coastline, that consists of a large, natural, harbour-like cove. Not only is this cove a popular tourist attraction due to its natural beauty, but it also has a rather important geological significance – its formation is vital due to the precise nature of this location’s geology. A band of limestone is responsible for the narrow ‘neck’ of the cove; however, the large ‘body’ of the cove is formed by softer clay being eroded more quickly than the limestone. However, the cove is prevented from eroding further northwards into the rock by the existence of harder greensand and chalk layers [4]. Although this is not the only cove along the Jurassic Coast, this is the most striking example of this feature along the shoreline. However, there are other coves, including Stair Hole to the west of Lulworth Cove, which also contains a natural arch, and Pondfield Cove to the east of Lulworth Cove.
The Undercliff
Other interesting erosional landforms are located along the Jurassic Coast. Between Seaton and Lyme Regis exists a phenomenon known as the ‘undercliff’. At this stretch of the coast, sandstone and chalk dominate the rock types; as these sedimentary rocks are rather erosive, and wave erosion cuts into the rock at sea level, this creates a phenomenon known as an ‘undercliff’ – in other words, a precarious cliff overhang. Although this feature is rather useful for creating great habitats for flora and fauna, it is very dangerous; over time, the undermined cliff will collapse into the sea below, often without any indication on the surface of the eroding undercliff below [5]. Therefore, people must stay away from the edge of the cliff at all times, even on a very calm day.
Chesil Beach
The coastal landscape along the Jurassic Coast is not only shaped by erosion, as there are also rather less destructive landforms along the coastline. Chesil Beach is a great example of this; stretching for 18 miles from West Bay to Portland, this is a shingle beach that is serves as one of the Jurassic Coast’s iconic landmarks. It is formed by flint and chert rocks from eroded sections of the Jurassic Coast [6]. These are often deposited here due to the angle of the coast changing slightly – rather than running west to east like other parts of the Jurassic Coast, the coastline here runs slightly north-west to south-east at this section. In addition, between Weymouth and the village of Abbotsbury, the pebbles act as a barrier between the English Channel and a large saline lake known as ‘Fleet Lagoon’. Designated as a Site of Special Scientific Interest by Natural England, this is a saline lake that stretches 10 km (6 miles) in length behind the beach. It is a very important feature – not only are lagoons a fairly rare feature along the British coastline, but this has the added importance of being a one of the few undisturbed brackish lagoons in the world. ‘Brackish’ is a word meaning that that water in this lagoon is not freshwater, but has a lower salt concentration than the sea does [5]. Furthermore, this lagoon provides a natural wildlife habitat for many animal species, in particular birds – not is this therefore an important feature in terms of supporting biodiversity, but it also attracts many birdwatchers.
Isle of Portland
The Isle of Portland is another very interesting feature along the Jurassic Coast. It is a tied island in the English Channel, at around 5km long and 2km in width, and its most northern edge is around 2km south of the port of Weymouth, which is on the mainland shoreline. The fact that it is a tied island means that, although it is not connected to the mainland by a natural land formation, it is attached to the Dorset shoreline by a natural bank of pebbles, which is Chesil Beach. The island itself is considered very important for its geology and landforms; it consists of rather high limestone cliffs (the limestone from this island is known as Portland Stone), as well as a rather rugged and rocky coastline. At the southern tip of the island lies Portland Bill, a headland upon which sits a lighthouse. Although the cliffs here are not too high, with the land gently sloping down from the island’s summit near the north of the island, to near sea level at Portland Bill, the coastline remains very rugged. Around the southern tip of the island, there are many rockpools and small gaps formed within the limestone, and the lack of cliffs here results in this section of the coastline being accessible to tourists.
Isle of Purbeck
Despite the name, the Isle of Purbeck is not an island, but is in fact a peninsula stretching out into the English Channel. It is surrounded by water on three sides: to the south and west exists the English Channel, and to the north is Poole Harbour and marshlands around the mouth of the River Frome. The Isle of Purbeck also marks the eastern end of the Jurassic Coast; the section of Purbeck within the Jurassic coastline will therefore be covered in this article.
Like much of the Jurassic Coast, cliffs, various rock formations, bays and valleys dominate the coastline. This runs through some of the most tranquil and iconic Dorset scenery. Kimmeridge Bay is a rather scenic area, with rather shallow water bordered with fossil-rich shale cliffs on either side. A few kilometres to the east, there is a large headland, known as Saint Alban’s Head, from which beautiful views of the sea and surrounding coastline can be obtained. However, on the eastern coast of Purbeck, there is a sequence of two headlands with a bay sandwiched in between – the southern headland (Peveril Point) consists of Portland limestone, whilst the bay in between (Swanage Bay) consists of clay. This is typical of a situation where softer material is eroded quickly than harder rocks, leading to the formation of these features. However, the northern headland – the aforementioned Handfast Point – is made from relatively hard chalk, and therefore exists as a promontory into the English Channel. Not only is this where Old Harry Rocks is located, but this also marks the easternmost point of the Jurassic Coast, just to the north of the town of Swanage.
Towns and Villages
There are many port towns and villages located along the Dorset coast, with the most notable ones being Exmouth, Sidmouth, Beer, Seaton Down, Lyme Regis, Weymouth and Swanage. Marking the western end of the Jurassic Coast, Exmouth is a seaside town at the end of the Exe estuary. Sidmouth, Beer, Seaton Down and Lyme Regis are examples of these small seaside towns nestled between hills in a valley, with cliffs on either side. At this part of the Jurassic Coast, the cliffs have a distinctive red-orange colour, and the towns itself are very picturesque, with old and beautifully-coloured buildings, and a nice pebble beach below the promenade. Beer is a quaint coastal village that contains many old buildings; once being supplemented by stone and flint mining, forestry, fishing and farming, Beer now relies primarily on tourism for its income [7]. Lyme Regis is another example of a tranquil seaside town, with attractions including the fossil museum, the Blue Lias Art Gallery and the Langmoor and Lister Gardens. Sweeping down a hillslope, these gardens contain many plants, mature trees and shrubs [8].
Weymouth is a larger port and seaside town; once a more industrialised area, this town still has a large harbour between the southern part of the town and the Isle of Portland, which is used for recreational sailing today. This venue was chosen to host the sailing events during the London 2020 Olympic and Paralympic Games [9]. Although there are other scenic towns and villages along the coastline that are definitely worth visiting, the last town in this article is Swanage. Located very close to the easternmost part of the Jurassic Coast, Swanage is another picturesque seaside town, which also contains museums, an art gallery and many pubs and tea rooms to choose from.
References:
[2] https://jurassiccoast.org/visit/attractions/lyme-regis-museum/
[3] https://www.earthmagazine.org/article/travels-geology-mesozoic-masterpiece-englands-jurassic-coast
[4] https://en.wikipedia.org/wiki/Cove#/media/File:Figure_lulworth_formation.png
[5] https://footscape.co.uk/coastal-erosion-along-jurassic-coast/
[6] https://www.visit-dorset.com/things-to-do/chesil-beach-p1306903
[7] http://www.beer-devon.co.uk/village-history/flint-mining-in-beer/
[8] https://lovelymeregis.co.uk/thingstodo/langmoor_and_lister_gardens
[9] https://www.bbc.co.uk/sport/olympics/18700142