Link to the English Heritage Survey Database
The following links are maps relating to this project.
Sites surveyed in 1996 (map)
Oldbury, Magnetometer survey plot
Oldbury, Magnetometer Survey Interpretation.
Liddington, magnetometer survey grey scale
Liddington, interpretation
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A vital step towards the management of archaeological sites in ways that will be beneficial to the survival of buried remains is the acquisition of more detailed information on the amount and types of archaeological feature that may survive more or less undisturbed beneath the ground. Non-destructive methods of site investigation provide an effective means by which this may be accomplished. In recent years they have assumed an increasingly important role in thematic assessments of particular groups of monuments, where identification of sites of high archaeological potential worthy of active conservation measures is imperative in a climate where resources have to be carefully targeted.
The Ancient Monuments Laboratory in collaboration with the Institute of Archaeology, Oxford has evolved a themed programme of geophysical survey to investigate a wide ranging sample of Iron Age hillforts in Wessex to address combined research and management issues concerning these important later prehistoric monuments. Rather than focusing only on individual sites when threatened, the Wessex Hillforts Survey Project employs a strategic approach, tackling a range of research issues related to the wider group of sites. As well as contributing to understanding of internal use and functional differences between various hillfort types in Wessex, the project is also providing valuable new information on a group of sites about which detailed archaeological knowledge is patchy. The results of geophysical survey will assist in the selection of management priorities (such as mitigation of plough damage) on the basis of the surviving evidence in their interiors mapped by geophysics. Contour survey of selected sites by the CAS is contributing to the appraisal and development of rapid survey techniques for generating surface models of earthworks as well as recording any visible interior features that may have escaped the long-term effect of cultivation. The surface and sub-surface data will be integrated to examine the complementary relationship between the different survey methods, and the resulting information will contribute to the better interpretation and presentation of the increasing number of sites with public access.
Surface traces of former habitation within hillforts have all too often been obliterated by prolonged cultivation and only a small number of hillforts have been excavated on a scale which allows the nature and density of their internal features to be adequately characterised. Amongst these there is considerable variation in the complexity of their internal arrangements and the intensity of occupation. Within Wessex, some such as Balksbury, Hampshire, have very few internal features, suggesting that they fulfilled a very different function from the densely occupied +developed' hillforts such as Maiden Castle and Danebury. Blanket magnetometer survey of hillfort interiors could potentially resolve a number of issues central to the study of hillforts, including whether all large, slightly defended early Iron Age enclosures are largely devoid of settlement (as the few excavated examples suggest); whether apparently contemporary centres occupying adjacent territorial blocks exhibit similar density and character of occupation; whether patterns of spatial organisation re-occur in particular categories of hillfort based on size, period, siting, or complexity of defences. Magnetometer survey could also identify other examples which exhibit comparable densities of occupation to developed hillforts such as Danebury; whether occupation occurs commonly outside hillforts, and how patterns of internal organisation in Wessex hillforts compare with those in other regions of Britain
The first season of fieldwork was completed in October 1996 and involved the near total magnetometer survey of nine separate hillforts of differing character all located on chalk or chalk capped with clay with flints in Berkshire, Oxfordshire, and Wiltshire. Modelling of site micro-topography was successfully carried out by the CAS on four sites suitable for this type of recording. The work included evaluating the use of global positioning system (GPS) technology in developing rapid 3D topographic modelling. Hillforts surveyed in 1996 included small defended enclosures only a few hectares in area (Alfred's Castle Oxfordshire), medium sized hillforts around 5ha in area with single and multiple ramparts and ditches (Barbury Castle and Liddington Castle, both in Wiltshire) and larger forts with elaborate defences (Oldbury Castle, Wiltshire) or simple earthworks (Martinsell Hill Camp, Wiltshire).
Oldbury Castle and Liddington Castle have produced the most spectacular results to date. A wealth of circular internal structures have been identified within the large multi-vallate enclosure at Oldbury (possibly the best results achieved to date from a magnetometer survey on a chalk hillfort), together with evidence of a substantial length of curvilinear ditch (not easily recognisable on the surface) which could represent part of an earlier pre-hillfort enclosure or the remains of an earlier smaller hillfort that was later extended. At the smaller univallate fort of Liddington Castle magnetometer survey has revealed the probable remains of a single large round-house (approximately 18m in diameter) located near the centre of the site with a surrounding spread of occupation activity including pits and curving ditches or gullies. Other sites such as Martinsell Hill Camp and Oliver's Camp show a comparative lack of internal occupation, although geophysical survey cannot prove beyond doubt the absence of archaeological features such as small postholes. The results of the 1996 surveys together with the results of a further nine surveys to be carried out in 1997 will be analysed in more detail during 199-98.
The project is intended to serve as a pilot which will allow EH to appraise the academic and practical value of themed geophysical survey work. When many groups and agencies are beginning to consider the issue of developing research frameworks to take British Archaeology in to the next millennium, a successful outcome to the project should provide a useful demonstration of the importance of non-destructive survey within such frameworks. The ability of geophysical techniques to further the development of hillfort research has been amply demonstrated by the first batch of surveys and the results to date provide a clear illustration of the considerable academic potential and wider relevance of themed survey.