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).
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).
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?
Iron Age hillforts must be one of the most visited types of archaeological sites in the country. Recently I have been up to Barbury Castle a couple of times and have been reminded how impressive and commanding this site is, not just because of its massive ramparts, but also its good state of preservation and all of the other archaeological features you can see from here. It is one of the most impressive of the 35 hillforts we have in the Wiltshire and Swindon area, with panoramic views that take in the Marlborough Downs and the Vale of Pewsey.
Barbury is located between Wroughton and Swindon and the County boundary, as well as parish boundaries, run through the middle of the hillfort. The hillfort was built in the Iron Age, probably around 700 BC and is likely to have been continuously used until the Roman invasion in the mid 1st century AD. It was one of a string of hillforts built close to the line of the Ridgeway, considered to be an ancient long distance routeway. Three other hillforts, Liddington, Uffington and Martinsell are all intervisible with Barbury. It is the most developed and most impressive of the Ridgeway hillforts, having double ramparts on the south side and triple on the north side (possibly an unfinished circuit). In places the banks or ramparts stand over 3 metres in height even now and in the Iron Age would have been topped with wooden palisades and defensive towers. Located at 262 metres above sea level Barbury was built on the highest point of the local area, a beneficial defensive position with commanding views of the landscapes below.
The ramparts at Barbury enclose an area of about 5 hectares and there were two original entrances that survive today at the east and west sides. Unfortunately there has been little modern archaeological investigation to tell us details of the lives lived at Barbury. However, the results of a geophysical survey carried out by English Heritage in 1998 indicate that the interior is littered with hundreds of pits (probably for grain storage) and other features, some of which are the remains of huts or roundhouses.
The interior of the hillfort as well as the ramparts have suffered some damage in the 1940s from the activities of American troops and the Home Guard who were based at the nearby Wroughton Airfield during the war and used Barbury as a training ground. The original hillfort entrances were unfortunately widened by American troops in order to get their trucks into the interior. Fortunately, we have a measured survey drawn in 1884 by General Augustus Pitt Rivers, the first ever Inspector of Ancient Monuments, to show how they would have been.
In 2010 and 2011, some geophysical and trenched evaluation was carried out at a site near the Woodbury Iron Age Settlements Scheduled Ancient Monument. This revealed some undated pits and an extension of the prehistoric field systems that are known to be present in the area, which are thought to relate to the Woodbury settlement. Although the initial results were unpromising, a fragment of human bone in one of the fills from the pits suggested that there might be more to this site than met the eye. Wessex Archaeology undertook the work for this site.
Once the site had been stripped of the topsoil, it became clear that there was more here than had been thought initially. The first and most obvious feature was the remains of a round barrow. The barrow was only now visible as a circular brown ditch cut into the white chalk. This picture shows the barrow, with the later Iron Age ditch running through it. This suggests that, unlike many other contemporary barrows, the mound for this one had been levelled before the Iron Age use of the land had started. In the base of the ditch was a a placed layer of flint pieces and part of an antler time, which may well have been used as a pick when the ditch was dug out.