As the only place where all four of the great Earth systems (land, sea, atmosphere, and humans) interact directly, coasts are one of the most continuously active parts of the Earth’s surface. 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.”

Durdle Door 1200px
Durdle Door on a spring evening. © Steve Belasco - stevebelasco.net

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.

Only the Jurassic Coast is recognized for the reality that its apparently destructive character both generates new coastal forms and provides constantly changing access to the previous environments (desert, deep ocean and coastal lagoons) of a period from about 251 million years ago to about 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 have occurred over the last one million years.

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.

Lulworth Cove - Rebecca Johnson
Lulworth Cove. © Rebecca Johnson
Worbarrow Bay and motor boat
Worbarrow Bay. © Steve Belasco - stevebelasco.net

Geomorphology of the coast

The geomorphology expressed on the Jurassic Coast itself is connected to landforms inland as well as on the seabed, which have been shaped (and will continue to be shaped) by wider marine and terrestrial processes. The appearance of the Site is largely defined by sub-aerial processes (rain, frost, wind, steams, etc) which carved the present landscape, for example the valleys between Worbarrow Tout via Lulworth to White Nothe (as seen in the image above).

Furthermore, the geology of those cliffs reveals very recent (in geological time-scales) Earth surface processes. Similarly, many of the present-day landslides depend on groundwater draining to the coast from catchments inland.

Offshore, the processes which shape the coast and affect its dynamics exist in a zone of variable width where waves influence sediment movement both onshore-offshore and alongshore, as well as in areas in which currents transport sediment, mainly sand, on-and offshore.

Sunbeams on Devonshire Point
Sunbeams on Devonshire Point. © Steve Belasco - stevebelasco.net

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 role in changing 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.

staying safe storm west bay
The power of the sea is continually eroding the coastline, as demonstrated in this image of a storm at West Bay. © Sam Rose

Looking internationally, the Australian islands of Lord Howe, Fraser, Heard and McDonald Islands are recognized for the role of marine erosion, dune behaviour and active geomorphological processes.

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.

Ha Long Bay sunset - Esin Üstün
Ha Long Bay sunset. © Esin Üstün via Flickr

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.