Unexpected archaeological discovery in Westbury

on Tuesday, 10 September 2019. Posted in Archaeology, Wiltshire Places

Exciting and unexpected archaeological discoveries show how no evaluation process for sites is fool proof. What happens next shows how important cooperation and communication is, particularly for the County Archaeology Service, who are tasked with supporting development AND safeguarding heritage. The critical concept is “significance” – how important are the remains; what is their potential to inform us about the past? Rachel Foster, Assistant County Archaeologist reports:

In 2017 Wessex Archaeology excavated a new housing development north of Bitham Park in Westbury. I had requested this work as a condition of planning permission, based on limited evaluation results. Unexpected discoveries demonstrated the challenges faced by Planning Archaeologists in understanding the significance of archaeological sites based on the results of trial trench evaluation. 

The 2018 National Planning Policy Framework states that local planning authorities should identify and assess the particular significance of any “heritage asset” that may be affected by a proposal. In line with this advice, we often ask for sites to be investigated before the determination of a planning application, so that we have that information. Evaluation usually this consists of geophysical survey followed by trial trench evaluation. The Wiltshire and Swindon Historic Environment Record which contains detail on archaeological sites, buildings and finds, informs our decision making.

Archaeological evaluation can feel like a game of battleships. When geophysical survey goes well, and reveals features that look like potential archaeology, we ask for trenches to be dug and the features investigated by commercial archaeologists.  The aim is to understand the significance of the site by investigating features within the trenches, which is not always so easy:  if geophysical survey has not been carried out or is unsuccessful, then trenches are placed either systematically or randomly across a site and there is potential to miss remains. Today, the trenching is usually a 3-5% sample of the development site but in exceptional circumstances, up to 10% may be carried out.  That sample of trenching should find archaeological remains within a site and provide enough information to understand the importance, extent and significance of any remains.  Results of evaluation will then inform our advice to the planning officer on the impact of the development on archaeological remains. Remains considered to be of national significance are likely to be preserved in situ and not developed, but other remains are likely to be investigate. Early knowledge about archaeology and its potential effect helps the developers manage their risk and adequately budget for excavation costs, as well as post-excavation work and publication.  

The geophysical survey results at Bitham Park didn’t show much other than a few lines representing ridge and furrow remains across parts of the site and a few other possible linear features. This image gives an example of the greyscale plot of the geophysical survey results (magnetromotry).

© Wessex Archaeology

Geophysical survey isn’t always reliable, so I asked for trial trench evaluation prior to determination of the planning application: in some cases, later ridge and furrow can hide earlier remains. As the geophysical survey indicated, there were remains of medieval/post-medieval ridge and furrow cultivation; however, my assessment that there might be more archaeology was correct.  Archaeological features were discovered across several trenches, mostly concentrated in the western part of the site. They included ditches, gullies and pits containing small, worn pottery fragments from the early/middle Iron Age and Romano-British periods (150BC onwards). Nevertheless, the significance and extent of the remains could not be fully understood, so I asked for a second stage of evaluation to provide more data. The extra information would help me define an area for archaeological mitigation – the full excavation of important features.  The results confirmed prolonged and intensive agricultural use from the medieval period (1066- 1540). This had truncated and displaced features and artefacts from the earlier Iron Age and Romano-British periods; however, theses features included and arrangement of post holes representing a possible structure (see trench locations of two evaluation stages below).

© Wessex Archaeology

On the basis of the two evaluations I asked for an area of excavation within the vicinty of where the most significant archaeological features were recorded, in the western part of the site and along a north-south trajectory.

In advance of the housing development an initial area was stripped with contingency and here’s an aerial view of the site below, can you spot anything interesting?

© Wessex Archaeology and Thomson Environmental Consultants

What was discovered were multiple phases of activity including a probable Early or Middle Bronze Age ring ditch (far right) and part of a suspected Middle Bronze Age field system. What was really interesting was during the late Bronze Age period an arrangement of palisades were constructed at the southern end of the site (bottom left) around a large roundhouse and a rectangular structure. This would have been an impressive structure and represents management of resources and the work of skilled craftspeople.

© Wessex Archaeology

To the north, groups of pits seem to indicate many more structures, including several roundhouses, rectangular structures, wells, pits and isolated postholes. Two trackways were also recorded, the principal track ran in a north-west to south-east direction across the site and was Romano-British in date. This track appears to have influenced the later medieval and post-medieval field arrangements, suggesting that it was still a visible feature long after the end of Roman rule.

This project shows how we work with our colleagues in the Wiltshire Planning Offices to ensure development can go ahead, but without losing vital information about our collective heritage. It also shows how working together can produce results without impacting development plans and helping the applicant avoid unexpected discoveries. A recent study by the Association of Local Government Archaeologists has shown that effective working by local authority archaeology teams like ours can save developers money by addressing issues early and effectively, by identifying risk and supporting mitigation plans. That mitigation can include further investigation but may also see the results of the archaeological works being used to enhance new developments, adding value and interest by using the past to inform the future.

For further information on this site see Wessex Archaeology’s article in the next Wiltshire Archaeological and Natural History Magazine. The ALGAO report may be seen here:

Many thanks to RPS Consulting and their clients, and to Wessex Archaeology and Wessex and Thomson Environmental Consultants for permission to reproduce plans and the aerial photograph.

Rachel Foster
Assistant County Archaeologist


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