Our dynamic coast

The geomorphology of the Jurassic Coast varies considerably along its 95 miles of coastline. The nature and interaction of the different rock types has, over millions of years, led to the development of textbook examples of geomorphological features, such as sea stacks, bays and headlands. Changes in the geomorphology of the coast can be explored further by area or by feature.

Coasts are one of the most active parts of the Earth’s surface, with all four of the great Earth systems (land, sea, atmosphere, and humans) interacting directly. This activity places coasts amongst the most biologically diverse (plants and animals) and intensively occupied (human) parts of the world. And these communities are dependent upon such dynamic processes which have shaped, and will continue to shape them, across many different scales of time and space.

The 95 miles of Jurassic Coast is no exception, indeed its UNESCO inscription boasts that it, “includes a series of coastal landforms whose processes and evolutionary conditions are little impacted by human activity, and the high rate of erosion and mass movement in the area creates a very dynamic coastline which maintains both rock exposures and geomorphological features and also the productivity of the coastline for fossil discoveries.” From the red mudstone cliffs of Orcombe Rocks in the west, the World Heritage Site stretches to white Chalk cliffs of Old Harry Rocks in the east.

All along this stretch of coastline, internationally renowned erosional features occur, such as Lulworth Cove, Stair Hole, Worbarrow Bay, Durdle Door, Chesil Beach, Old Harry Rocks, and some of the largest coastal landslides in Europe. The dynamism of our coast is primarily a result of the constant variability of our climate. The way in which the coast changes depends on both, local climate and the climate of the North Atlantic, as well as on historical changes in climate.

The impact of waves driven by Atlantic storms, the effects of frosts breaking into the cliffs, or the long-term changes in sea level each play a crucial role in shaping the coast.  This coast has a very long history of not only these day-by-day changes but also the impact of rare but ferocious storms. Looking internationally, the Australian islands of Lord Howe, Fraser, Heard, and McDonald Islands are well-recognized for the role of marine erosion, dune behaviour, and active geomorphological processes in formation of these islands.

Others, such as the Wadden Sea on the German and Dutch coasts, and Henderson Island in the Pacific Ocean, are recognized for their dynamic marsh and reef ecosystems. This contrasts with others, such as Ha Long Bay in Vietnam and the Mauritanian Banc d’Arguin, which have extraordinary coastal scenery or dynamic beach systems.

Very few of the UNESCO site descriptions for World Heritage Sites around the World identify geomorphological processes and erosion as being key features of the sites. Among them, only the Jurassic Coast has been recognized for its apparent destructive character generating both new coastal forms and providing constantly changing access to the previous environments (desert, deep ocean, and coastal lagoons) for a period ranging from approximately 251 to 65 million years ago.

The last 65 million years have included significant geological faulting and folding. These geological structures, the strata they affect, along with the associated fossil biodiversity they contain are exposed in the rocks of the Jurassic Coast, largely as a result of the dynamic processes resulting from sea level rise and associated erosion that has occurred over the last one million years.

Our Dynamic Coast: About the Author

The ‘Our Dynamic Coast’ section of our website and associated digital content was based on a manuscript written by Professor Vince May in 2016.

We are fortunate enough to be able to collaborate with Vince and to use his manuscript to tell the inspiring stories of the Jurassic Coast’s dynamic processes.

Vince is an expert on coastal geomorphology and an emeritus professor at Bournemouth University. He has been involved with the Dorset and East Devon Coast World Heritage Site since the idea to bid for World Heritage Status was first suggested.

He is also the author of many scientific publications about the Jurassic Coast, including several Geological Conservation Review articles upon which the outstanding Universal Value of the Site is based, and through which the Site is protected via coastal SSSI designations.

Vince is currently the Vice chair of the Partnership Advisory Committee for the Jurassic Coast Trust, and continues to be a committed advocate of Earth Science and the value of our shared geological heritage.