Mapping the coast edge: Flimston Bay, Pembrokeshire

Flimston is a baseline study site for the EU-funded Ireland–Wales CHERISH project (2017-2023), which is studying climate change and eroding coastal heritage in Ireland and Wales

Flimston Bay coastal promontory fort is a spectacular Iron Age site commanding a precipitous cliff-top position in south Pembrokeshire.

Part of the Castlemartin military training area, the carboniferous limestone of the southern cliffs is constantly eroding into contorted headlands, natural arches, and offshore stacks. The coastal fort even encloses a yawning chasm called ‘The Cauldron’. In 2014, a major cliff fall took away 5m of the promontory fort’s eastern ramparts.

Flimston is a baseline study site for the EU-funded Ireland–Wales CHERISH project (2017-2023), which is studying climate change and eroding coastal heritage in Ireland and Wales. Part of the project ethos is to create new, highly accurate baseline data for poorly mapped heritage sites, so that coastal erosion can be accurately monitored in the future.

This Digital Elevation Model is the result of a new drone survey covering 1.3km of coastline, which was carried out in August 2020 by the CHERISH Project team from the Royal Commission, Wales. Roughly 1,800 vertical images of the site were captured and processed to create a highly detailed 3D model showing boulders and shingle on the beach, the great curving Iron Age ramparts that defend the headland, and the precise position of the fragile cliff edge.

This can be compared to a detailed survey of the fort made by the Royal Commission back in 2009, which mapped around 20 house platforms inside the fort. Increasing groundwater and storminess, together with penetrating droughts, caused by climate change continue to take their toll on these fragile coastal heritage sites; a detailed record of the most-important monuments is imperative for their future management.

Text: Dr Toby Driver, Senior Investigator, CHERISH Project, Royal Commission.
Image © Crown: CHERISH Project 2020. Produced with EU funds through the Ireland Wales Co-operation Programme 2014-2022

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