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Severn Estuary RCZAS NMP

Severn Estuary RCZA locationThe National Mapping Programme (NMP) component of this Rapid Coastal Zone Assessment Survey (RCZAS) project was funded by Engish Heritage and carried out by Gloucestershire County Council Archaeology Service. 

The aerial survey focused on the intertidal zone and up to 1km inland. The project aim was initiated primarily to provide an assessment of the Severn Estuary’s archaeological resource and to inform the future management of that resource in response to the threat from natural and human processes.

Wreck of the Staghound (NMR18676/10). © English Heritage. NMR.

Remains of British “block ship” the 1942 “Staghound” in Woodspring Bay, near Clevedon photographed on 19-FEB-2000 (NMR18676/10). © English Heritage. NMR.

Ancient Coastal Fisheries

Some of the most significant archaeological features identified were the numerous coastal fish weirs and traps located in the intertidal zone of Bridgwater and Blue Anchor Bays, dating from the 10th century period to the 20th century. These have been constructed in an intriguing variety of designs and materials.  Built of wood, stone or a mix of both, at least four morphological types of fish weir were identified by the aerial survey.

These variations may reflect the availability of raw materials, changes in construction design over time, the types of fish being targeted, or a combination of these factors. Detailed examination of air photographs reveal that these fish weirs were constructed and reconstructed and the raw materials reused, especially those built of stone. Many fish weirs are also visible overlying, intersecting or abutting each other.

Medieval stone fish weirs in Minehead Bay (NMR 18300/10). © Crown copyright. NMR.

A medieval stone fish weirs in Minehead Bay photographed on 19-MAR-1999. These are still maintaned by local fishermen (NMR 18300/10). © Crown copyright. NMR.

Second World War Coastal Crust Defences

Second World War military coastal crust defences were prominent features in the Severn Estuary intertidal zone, providing an interesting comparison with other military defences around Britain’s coastline such as those recorded by the Suffolk NMP aerial survey. The aerial survey highlights the strategic importance of camouflage used to disguise coastal military defences, especially pillboxes. The historical air photographs are valuable as few surviving examples retain their original camouflage. Numerous pillboxes were positioned along the coast between Porlock Weir and Blue Anchor, of which 28 were identified as a non-standard design known as an infantry section post, which were are a unique part of the coastal crust defences in the NMP survey.

 Infantry Section post and pillbox near Dunster (MSO31206-PO-056). English Heritage (NMR) RAF photography.

An Infantry Section post and pillbox near Dunster photographed by the RAF on 27-JUN-1941. These had beach pebbles cemented to their exterior to help conceal them within the landscape (MSO31206-PO-056). English Heritage (NMR) RAF photography.

Historical Images: An Important Pictorial Record

Aerial photographs taken during the Second World War remain an important historical pictorial record of the nation’s defences, as most of the sites recorded were no longer visible within a few years of the war’s end. Using these wartime images has revealed anti-invasion defences of the Severn Estuary to be far more extensive than previously thought.

An oil QF decoy at Portbury (RAF 106G/UK/1288 5240). English Heritage (NMR) RAF photography.

An oil QF decoy site located in the mud at Portbury photographed by the RAF on 25-MAR-1946. It was created for the defence of the docks at Bristol and Avonmouth, which were and still are a vast area of oil and fuel storage tanks, the protection of which was paramount. The oil QF decoys were designed to do just that, by acting as bomb-damaged storage tanks to divert the bombing away from real oil supplies. They are both located away from the main Avonmouth region but close enough to confuse Luftwaffe bomber navigators (RAF 106G/UK/1288 5240). English Heritage (NMR) RAF photography.

Trial Lidar Assessment

The NMP project included a trial lidar assessment of part of the flood plain of the River Parrett, Somerset and an area of possible Roman land reclamation at Elmore, Gloucestershire. Overall lidar was shown to be complementary to aerial photographs in both the trial areas for the identification of archaeological sites and also for assessing their survival.

The images used on this page are copyright English Heritage unless specified otherwise. For further details of any photographs or other images and for copies of these, or the plans and reports related to the project please contact the English Heritage Archive.

For further information on a project or any other aspect of the work of the Aerial Survey team please contact us by email via the link above.


Aerial Investigation and Mapping - Swindon
Heritage Protection Department


Supported by

The project was carried out by staff from

Gloucestershire County Council Archaeology Service