Colour aerial photo showing concrete runway with areas of hardstanding on either side surrounded by fields of grass and crops
Site of the former Dunkeswell Airfield photographed on 08-AUG-2007 (EHA 24672/29) © Historic England
Site of the former Dunkeswell Airfield photographed on 08-AUG-2007 (EHA 24672/29) © Historic England

The Blackdown Hills AONB and East Devon River Catchments Archaeological Survey to National Mapping Programme Standards

The Blackdown Hills Area of Outstanding Natural Beauty (AONB) on the Devon and Somerset border has been a relatively under-studied landscape. The survey was designed to provide good archaeological information to inform land management. This particularly related to potential changes due to initiatives to reduce water pollution from agriculture. These targeted the catchments of the rivers Sid, Otter and Axe. Work also focussed on major infrastructure improvements along the route of the A30/A303. This could have potentially significant impacts on the landscape along the busiest route through the AONB.

General trends

Several themes were identifiable from the survey results. It recorded ritual or religious monuments from the Neolithic to the medieval period. It also documented deserted settlements and defensive and fortified sites of medieval and later date. However,  two further themes dominated the results. These relate to medieval and post-medieval farming and industry. It seems likely that these have greatly influenced the character of the Blackdown Hills AONB.

Some of the more important findings are discussed in more detail below.

Earthwork preservation was good, with 90% of all features recorded visible as earthworks. Fewer than 7% of were visible only as cropmarks or soilmarks. This survival and the medieval character of the landscape may go some way to explain why the survey identified very little evidence of prehistoric settlement.

The inner circle revealed

Excavation in the early 20th century identified the characteristic interrupted ditches of a Neolithic causewayed enclosure at the southern tip of the Iron Age hillfort at Hembury. It is one of only four causewayed enclosures known in Devon. Lidar-derived images show a broad, shallow curvilinear ditch visible to the south. The survey interpreted this as an inner circuit of the causewayed enclosure. Recent geophysical survey supports this interpretation.

Abbey Days – New data at Dunkeswell Abbey

The Cistercian order founded Dunkeswell Abbey in 1201 and it was dissolved in 1539. Fishponds survive to the west of the abbey and some remnants of abbey structures have been incorporated into existing buildings. However, much of the monastic precinct was demolished after dissolution.

Local writers reported in 1877 that in dry summers the foundations of the Abbey buildings were visible as parchmarks under pasture. Over 100 years later these cropmarks were recorded on oblique aerial photographs. From these the survey transcribed the plan of the east range of the Abbey. To the east of the church, are earthworks visible on lidar derived images. These may provide previously unrecorded evidence of the organisation of the monastic precinct.

Forgotten Castles

At either end of a natural ridge, the earthwork mounds and terraces of Buckerell and Bushy Knap are visible on lidar derived images. These were previously interpreted as barrows, park features or simply natural knolls. Reassessment using lidar data supports their reinterpretation as small motte and bailey castles. The close spacing of the mounds and their association with a deer park to the south might support the interpretation of an evolution in function. They began with an early, post-conquest defensive role at Buckerell Knap. Over time, this progressed to a more symbolic, high status and comfortable site at Bushy Knap.

The Blackdowns at War

The Second World War had a profound effect on the Blackdown Hills. The South-West’s landscape of rolling hills and moors, river valleys and wetlands made siting airfields difficult. The RAF saw the potential of the Blackdowns plateaux. They quickly exploited it, constructing four airfields within the project area. These were RAF Upottery and RAF Dunkeswell in Devon and RAF Culmhead and RAF Merryfield in Somerset.

The roles of these airfields evolved throughout the course of war. During the early stages of the war the airfields in the South-West largely fulfilled training, support, and coastal reconnaissance roles. As the war progressed, however, their role changed. They played an increasingly central role, both during the Battle of the Atlantic and in the preparations for, during and after, the invasion of Normandy.

Although away from the coast, the threat of invasion was also felt in the environs of the Blackdown Hills. A concentration of defensive structures and earthworks dominated the east of the project area. These are largely associated with the Taunton Stop Line, probably the most complete inland defence line in the country.

The Stop Line was constructed across the narrowest part of the South West peninsula during the early years of the Second World War. This was the time when the threat of invasion was greatest. If an invasion penetrated the ‘coastal crust’ defences, the Stop Line was intended to slow their advance.

The defences followed natural and artificial barriers such as rivers and railway lines. They included anti-tank ditches and concrete anti-tank obstacles, barbed wire entanglements defended by gun emplacements and pillboxes. Anti-tank mines, road and railway blocks and bridges prepared for demolition formed a further layer of defence. By April 1941 the emphasis had changed. Now the emphasis was on anti-tank islands and centres of resistance that could be defended by the limited personnel available. Because of this the in-depth defences were never completed.

It’s the Pits – how extraction shaped the character of the Blackdown Hills

The survey has improved our understanding of the extent of locally significant extractive industries. This includes large scale industries, such as iron ore mining and whetstone mining. It also covers smaller scale quarrying, such as gravel, sand, chalk, clay and marl extraction.

Roman iron ore extraction and post-medieval whetstone mining was very intensive. However, the smaller scale clay, chalk and marl extraction probably had the most persistent effect on the character of the AONBs landscape.

Lidar data, has allowed us to identify and record very subtle earthwork features that are sometimes not visible on traditional aerial photographs. Lidar data can also often allow us to ‘see through the trees’ to record features otherwise obscured by tree cover. This data revealed that many woods, copses and orchards obscured large disused pits. It also greatly increased the number of smaller disused pits identified in open fields. Such pits were the monument type most frequently recorded in this survey.

Many were probably marl pits. ‘Marl’ is the name given to a mix of clay and limestone used as a form of fertiliser. Marling mixed the alkaline clays with more acidic and less fertile sandy soils, reducing acidity and improving moisture retention. Pliny described marling in Britain and Gaul in the first century AD. However, it was probably most common in Britain from the medieval period, reaching a peak between the 16th and 18th centuries. It is probable that many marl pits went out of use by the 19th century when modern fertilisers made them uneconomical.

‘Old Marl Pits’ are a common feature noted on the Ordnance Survey First Edition map. Their distribution matches the mudstone bedrock recorded by the British Geological Survey. However, it is probable this term was also mis-applied to other pits, such as clay and chalk pits.

Many old pits did not remain disused. Charles Vancouver, in his 'General View of the Agriculture of the County of Devon' in 1808, wrote:

“It is usual in the marly parts of this country to appropriate for orchards the large excavations formerly made in digging marl: here the apple trees are protected from most winds, and continue to flourish and bear longer than in less secure situations.” Vancouver 1808, 243.

Previous surveys have identified the creation of earthwork banks in orchards to improve drainage and give greater soil depth for tree planting. The surevy recorded such banks within and around many former extractive pits on the Blackdown Hills. In some cases these were even associated with former pottery industries. Many of the Blackdown Hills’ former extractive pits had a second lease of life as orchards and other woodland, which are now so characteristic of the AONB landscape.

The project

The survey examined all readily available aerial photographs and other relevant sources, such as lidar data, for the whole of the Blackdown Hills AONB excluding a small area that was assessed as part of a previous survey The survey area also included a small part of the East Devon AONB on the southern edge of the survey area and an area to the north and east. This took in the section of the A358 between Taunton and the A303 that will also be affected by road improvements. In total, an area of 546 square kilometres was surveyed.

The survey was carried out by a team from AC archaeology, hosted by Devon County Council and in partnership with Somerset County Council. More information can be found on the Devon County Council project webpages.

The images used on this page are copyright Historic England 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 Historic England Archive.

For further information on a project or any other aspect of the work of the team please contact us via email using the link below.


Cain Hegarty

NMP Project Manager for AC Archaeology

Cain has worked in archaeology since the late 1990s, beginning his career excavating sites throughout the Midlands. He then branched out into archaeological graphics, visualisation and the archaeological application of GIS. In the early 2000s he began working on large area aerial survey projects and has worked on similar projects to the present day. Recent work has focussed on the landscape of the South-West, from Exmoor National Park to the south coast of Devon.

Contact Cain Hegarty