Securing a Future for Essex's Past
by Paul Gilman
Heritage Conservation Planning Division
Essex County Council England
Editor's Note: In attempting to understand the past, archaeologists have often employed some of the most up-to-date techniques including GIS. In Essex, England, the County Council's Archaeology Section has often led the way in the use of computing. The Historic Towns Survey provided the section with its inaugural use of GIS. The Archaeology Section continues to find new and more powerful ways to use GIS.
The catalyst for the development of GIS by the Archaeology Section was the Historic Towns Survey project. English Heritage, the national body for the management of heritage sites in England, funded this survey as part of a national program designed to improve the understanding and protection of urban archaeological remains.
The project design was prepared in 1995 at about the same time that the County Council's map management system was coming to fruition. In considering the needs of the project, it was clear from the outset that a wide variety of data would be collected, almost all with a spatial component. Data on Listed Buildings, excavations, cartographic and documentary information, as well as data from Essex Sites and Monuments Records (ESMR) would be included.
Since 1984 the Archaeology Section has been compiling ESMR, the most comprehensive and up-to-date computerized record of all known archaeological sites and finds in Essex. ESMR is used to monitor planning applications and other proposals for development to ensure proper consideration is given to the need to protect and/or record archaeological remains.
Linking GIS to Existing Sources
An important part of the Historic Towns GIS application is the link to the ESMR database. The database, supported by Ordnance Survey map sheets, shows the location of various sites and finds. GIS provides the potential not only to allow this information to be more easily displayed but also to analyze ESMR data. The project began using an Oracle-based application, "Monarch for SMRs" (Sites and Monuments Records), provided by the Royal Commission on the Historical Monuments of England (RCHME). This link had to be built into the ArcInfo and the ArcView GIS aspects of the project.
Other data such as Listed Buildings and paper and photographic archives are also being transferred to digital media, suitable for linking to GIS. The end result will be a comprehensive and integrated resource to support the work of a new Heritage Conservation Group. Two powerful ArcView GIS extensions, ArcView 3D Analyst and ArcView Spatial Analyst, are being used to support research and improve understanding of the historic environment.
The Historic Towns project was based on a survey that was carried out in the early 1980s that was published by Essex County Council in 1983. The survey was adopted as the Supplementary Planning Guidance (i.e., the document provided detailed information and recommendations as to the way the Council should deal with planning applications in historic towns) by the County and District Councils in Essex.
Archaeological excavations and observations since 1983 have generated much new information. Moreover, the way archaeology was handled within the English planning system has changed, principally as a result of government guidance. The result was that the County's historic towns were in urgent need of reassessment.
The Historic Towns Survey project has been carried out in three key stages--data collection, assessment, and strategy. GIS played an important role in all three of these phases.
Various types of information associated with the project were brought together and added to the database. Whenever possible, this information was digitized using ArcInfo. Information from ESMR that was digitized could be checked using the Monarch database to verify that the correct feature was being digitized and allow attributes to be entered into a table in the native INFO format including the ESMR number.
Listed Buildings data, based on a Microsoft Access database created by the Archaeology Section, and historic cartographic records were also included. Since the cartographic records were created at various dates to differing standards of accuracy, it was not possible to digitize directly from these maps. The approximate outline of a map was drawn on the modern map base, and the outline was then digitized.
The Historic Towns project officer produced an assessment for each town under consideration. Each assessment summarizes the current state of knowledge about the town, supported by maps for each major period--Roman, medieval, postmedieval--that were produced using the GIS. These maps identify any components (castle, urban defenses, marketplace, urban housing, parish church) known to exist in the town.
In the final stage, a strategy to guide management of urban monuments and archaeological deposits was developed. A number of zones of archaeological importance for each town were determined. It is likely that these zones will be linked to the local plan for each town that should contain a general policy on urban archaeology cross-referenced to the strategy.
A Case Study: Castle Hedingham
Castle Hedingham is a good example of how this approach is being applied. As the name indicates, this settlement is based on a castle. It was built in the twelfth century by the de Veres family, Earls of Oxford, who were one of the most powerful aristocratic families in England. The evidence suggests that, like many other rich landowners at that time, they founded the town to generate income from rents levied on the inhabitants and from trade. The castle is a Scheduled Ancient Monument. For the rest of the town, ESMR's coverage is more limited and is mostly based on reports of finds and a few archaeological observations.
The Historic Towns project has allowed coverage to expand and to become more systematic. For example, one of the most important sources of information about Castle Hedingham in the medieval period is a map produced by Israel in 1592. The outline of this map was transferred to the GIS. The RCHME recently surveyed the castle earthworks and has produced a detailed history of both the castle and the town.
Previously, ESMR provided a partial, one-dimensional picture of the town. The assessment, based on a wider variety of information collated through the GIS, gives a more detailed picture of the town in both the medieval era and postmedieval eras. The core of the historic town of Castle Hedingham, as indicated by the location of the parish church, marketplace, and most of the historic buildings, is some distance from the castle.
Evidence in the form of earthworks attached to the castle and old property boundaries indicates that the castle originally included a large outer enclosure, known as a bailey, that has since almost entirely disappeared. The zones of archaeological importance within the town were identified. Once these zones are accepted, this information can guide the planning authority, Braintree District Council, in their response to development proposals.
Castle Hedingham illustrates how the use of GIS is enhancing information provided in the ESMR data set by relating it to other types of data, notably Listed Buildings and modern and historic maps. GIS is a dynamic system that can be changed and adjusted as new knowledge is obtained about the exact location of particular features. Castle Hedingham's town defenses have been plotted using a sixteenth-century map, traces of surviving earthworks, modern map features, and the evidence of archaeological observations. It is likely that the mapping of these features can be refined in the coming years as fresh opportunities for investigation arise.
Expanding the Use of GIS
With the successful use of GIS within the Historic Towns project, the use of GIS with the rest of the ESMR data was considered. Information in the ESMR can already be displayed as point data from the main database, and the process of digitizing all the ESMR site boundaries has been started. This point data provides new opportunities for display and analysis, which simply did not exist or were impractical with the old manual map-based systems, particularly the ability to easily and rapidly produce distribution maps of particular sites.
Mapping the distribution of medieval moated sites revealed a greater density of sites in some parts of the coast than in others, especially in the central and northwest portion of Essex in areas of mostly heavier, clay soils. Revealing these patterns opens new avenues of research.
Mapping the area around the Blackwater Estuary, the location of salt-working sites in the Late Iron Age and early Roman salt-working and a Late Roman fort, provides another example of analyzing point data. Most of the salt-working sites follow the line of the five-meter contour, suggesting that this approximates to the Roman shoreline. Since that time, land has been reclaimed from the sea for agriculture. Consequently, the true strategic location of the fort is less easy to appreciate. The contour lines show that the fort would originally have lain at the end of a low peninsula with the sea on three sides--an excellent defensive location.
Through the linking of ESMR to the GIS, the Archaeological Section has gained access to a wide variety of data sets including topographical data, such as contours and rivers, and planning constraints such as Conservation Areas and Sites of Special Scientific Interest. Much of this data was not previously available even in nondigital format. Access to this data has opened up new possibilities for research and provides a more holistic approach to planning.
Looking into the Past
The powerful ArcView GIS extensions, ArcView Spatial Analyst and ArcView 3D Analyst, are taking the Archaeology Section's GIS into an entirely new dimension. Using ArcView Spatial Analyst, data on moated sites distribution can be used to create density maps that reveal concentrations that can indicate the progress of medieval clearance of forests for settlement.
Using a digital terrain model from the Ordnance Survey and ArcView Spatial Analyst, elevation surfaces for the whole County and for particular areas have been created. Using the hillshade tool, a relief map was also generated that helps researchers understand the location of archaeological and historic sites as well as provides a more interesting and realistic background for other data. For example, in the early nineteenth century, defenses were built south of Chelmsford to prevent invasion from the coast to London. While only a small portion of these earthworks have survived, their location and outline are known. When their location is displayed against the elevation surface, their location on a low ridge can be readily appreciated.
ArcView 3D Analyst is being used to create landscape models based on the Ordnance Survey digital terrain model and digital contour data. This allows researchers to look at sites in a landscape setting, something that is often difficult or impossible to do in the field as modern development usually obscures views. The landscape around Castle Hadleigh, shown is now a ruin and only two towers survive. By extruding a three-dimensional shape based on the Ordnance Survey two-dimensional outline, the dominant siting of the castle is immediately apparent.
The ArcView GIS extensions offer many other potential avenues for research, and other tools, such as visibility tools, can also be used. A recent exercise involved the analysis of visibility from an important prehistoric site at Springfield Lyons, northeast of Chelmsford, the site of a ceremonial enclosure in Neolithic times (c. 4,000-3,000 B.C.) and a fortified enclosure in the Late Bronze Age (c. 1,500-1,000 B.C.). A three-dimensional map of this area indicates that it would have been possible to see the contemporary Cursus (a ritual monument) in Neolithic times. For the Bronze Age site, other contemporary sites could also have been visible at Boreham and Great Baddow.
While this model does not allow for the possibility for woodland intervening, it does show that the overwhelming proportion of the view from the site would have been eastward toward the adjacent Chelmer Valley. This type of study, which is becoming increasingly common in archaeology, provides insights into past landscapes showing how sites functioned and how past peoples viewed their world.
The Future of the Past in Essex
Much has been achieved in recent years in the application of GIS to archaeology in Essex County Council. GIS is now an essential tool for understanding Essex's past and is making an increasingly important contribution to the conservation of that past for the future. The approach described in this article will create a unique digital resource to support research and serve as a resource for the planning system to ensure that remains of that past survive for present and future generations to study and enjoy.
About the Author
Paul Gilman holds a bachelor of arts degree in archaeology from the University of Durham, England, and a certificate in archaeology from the University of Oxford, England. He manages the Heritage Information and Records Section of the Heritage Conservation Group, Essex County Council and has a particular interest in the application of information technology to Heritage records.
Brown, M., Hedingham Castle, Essex, unpublished report, Royal Commission on the Historical Monuments of England.
Department of the Environment, Planning Policy Guidance Note 16, "Archaeology and Planning," England: Her Majesty's Stationery Office, 1990.
Eddy, M. and M. Petchey, Historic Towns in Essex, England: Essex County Council, 1983.