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The Stonehenge & Avebury World Heritage Site comprises two discreet areas centred on the world famous henge monuments. Whilst being geographically separated by some 20km, both regions are characterised by the proliferation of prehistoric archaeological sites, notably from the Neolithic and Bronze Age but with sites of all periods as well.
Wessex Archaeology undertook a pioneering condition survey in 2001 for the Stonehenge part of the World Heritage Site, utilising a mobile Geographic Information System (GIS) equipped with Global Positioning Systems (GPS) for field data capture, supported by an extensive digital photographic record.
In 2010, Wessex Archaeology were commissioned by English Heritage to undertake the periodic resurvey for both the Stonehenge part of the World Heritage Site and also the Avebury part plus measured survey of the upstanding earthworks across both parts of the World Heritage Site.
Data driven monitoring
The approach taken is based around the idea of being data driven ie field observations are made which are then validated and used to make detailed assessments and management recommendations. This is a very different approach from simply making assertions whilst out in the field which are then collated and reported on as the former allows for very fine grained analysis and evidence based assertion whereas the latter is very much implicit and dependence on the expertise and consistency of the field team.
Wessex Archaeology routinely deploy mobile GIS for such projects to facilitate the gathering of robust, standardised field data in a rapid fashion. In the hands of expert field teams, data gathered is systematic and consistent and compliant with national and client specific standards, able to be analysed immediately on return to the office without the need for manual data entry of recording forms. For this project, terminology was derived from the Inscription wordlists maintained by the Forum for Information Standards in Heritage (FISH), making it compatible with other datasets using these national standards and suitable to feed into larger monitoring programmes such as Heritage at Risk.
This system is the best way of recording and analysing monitoring information in a rigorous and robust manner.
Field Recording & post fieldwork analysis and reporting
Mobile computers running GIS and equipped with GPS are used to capture spatially referenced assessments so every single piece of data gathered can be related to a real-world location using the British National Grid. Importantly, every observation is supported by photographic records, again all of which are spatially referenced. The structured data gathered can be loaded into desktop GIS back at the office as fieldwork progresses providing feedback for the field teams. Database Management Systems (DBMS) and GIS are then used to validate, analyse and report on the data, removing the need for the majority of manual data handling and thus freeing up valuable time for archaeologically important issues. Maps and plans can be produced directly from the GIS to visually present results and indicate change.
Measured survey
In addition to the condition assessment, the height of earthworks was to be accurately recorded. Wessex Archaeology decided that our survey grade Global Navigation Satellite Systems (GNSS) would be the best solution for this task and furthermore, whilst the field teams were deployed, capturing extra measurements would not significantly increase the time take to complete the survey. As such, transects of points across earthworks were recorded.
This data was again loaded into GIS back in the office and used to produce a series of over 1000 maplets for surveyed sites, each of which showing a location plan of the site and surveyed transect plus a profile graph of the height data.
Conclusions
The use of mobile GIS for recording data in the field allows for more robust, data driven survey methodologies. Assertions and recommendations are all based on observations made in the field then validated and anlysed, supported by evidence. Data handling time is reduced providing the most efficient way of monitoring archaeological sites and landscapes.