Digimap Case Study:
Neolithic Visual Environments on the Isle of Wight
Author
Kayt Lamballe Armstrong
Title
Neolithic Visual Environments on the Isle of Wight
Date
Spring 2005
Application Area
Archaeology
Application to other subject areas
Landscape geography
Project type
Coursework for MSc in Archaeological Computing with specialisation in Spatial Technologies
Summary
A series of viewshed calculations were performed for the three known Neolithic monuments on the Isle of Wight using Digimap DTM data and the ArcGIS viewshed functions and raster calculator. The results of these were discussed with reference to site visits and observations in order to comment on the observed differences in the character of the viewsheds between the three monuments.
Datasets Used
Name: Digimap Profile DTM, Ordnance Survey 25,000 scale map sheets, Isle of Wight County Sites and Monuments Record
Source: Digimap, Isle of Wight County Council
Aims and Objectives
The project aimed to explore the viewshed characteristics of the three known Neolithic monuments on the Isle of Wight, and where possible make meaningful (and statistical) comparisons between them. I was particularly interested in examining views over land vs, views over the sea, intervisibility and employing ‘Higuchi distance analysis’ as pioneered by Wheatley and Gillings (2000), which allows a more humanistic interpretation of the experience of distance than simple numerical outputs. These analyses were chosen to attempt to further our understanding of Neolithic culture as it has been shown that visibility within the landscape seemed to play a role in the choice of location for these monuments. By examining the differences in the characteristics of the viewsheds, I was able to start to think about the reasons for these apparent choices by past cultures, and so gain understanding.
Methodology
The Profile DTM data was imported into ArcGIS and then ‘mosaiced’ into one large raster DTM for the whole of the Isle of Wight. This was then resampled to remove the bathymetric data to give a ‘flat’ surface to the sea at 0m OD. A series of simple binary viewshed calculations were performed, showing what was visible from each monument, and also where each monument was visible from. These binary viewshed layers were used in conjunction with the raster calculator and with other functions within the GIS to look at direction, land vs. sea and Higuchi distance bandings. Counts of visible vs. invisible cells in the resulting rasters, or each direction/ distance band/ land/ sea were then exported for analysis within a spreadsheet. The intervisibility of the monuments was also checked. Comparisons between the ‘viewsheds’ generated within the GIS and what was actually the case on the ground were made with a series of site visits to the monument locations and the results were found to compare favourably.
Results
The pattern emerging is that of similar characteristics (despite being very different monuments) at Tennyson and Afton Down, and a quite profoundly different experience at the Longstone. The associations at the first two sites could be described as: Open, North and South, Intervisible, Near to the Sea, White and Green, Chalk, Over a River
The Longstone could be described as: Restricted, Directed, Easterly, Removed from the Sea (whilst referencing it), No Fresh Water., Hidden, Red, (Roughly) Worked Stone / Sandstone.
Many of these characteristics are somewhat subjective, but the detailed project results show that the noted differences have some numeric basis. The problem is what they actually meant. If the classification of the monuments are all correct, then they were all involved in some way with the disposal of the dead, and their transformation into something 'other', but present. The frustration is that we have no relative chronologies for these sites. We do not know therefore, if the differences observed could be a temporal variation with the same group, or an expression of a different identity, happening concurrently. It's possible that all the monuments were in use by the same group of people, at the same. Do the differences therefore represent different social strata? Varying levels of access to rituals and power? Bradley (1998) has shown that a possible sequence of typology is: causewayed enclosure, earthen barrow, chambered barrow. Therefore, temporal variations within the same community are favoured by the author as the reasons for the differences, with funerary ritual changing to reflect changes in society during the Neolithic. It would be wrong, at this stage to comment on what the changes in funerary rites, reflected by the monument locations, 'map' to in terms of changes within the society concerned.
Additional Information
References and/or acknowledgements
Wheatley, D. and M. Gillings (2000). Vision, perception and GIS: Developing enriched approaches to the study of archaeological visibility. IN Lock, G (ed) Beyond the map: archaeology and spatial technologies. Amsterdam, IOS Press.
Bradley, R (1998) The significance of monuments: On the shaping of human experience in Neolithic and Bronze Age Europe. London, Routledge
Thanks are due to Dr Wheatley for his assistance and guidance during the project, and for inspiring the work in the first place.
Publishing Institution
University of Bournemouth, University of Southampton
Contact us at: edina@ed.ac.uk
EDINA, Causewayside House
160 Causewayside, Edinburgh
United Kingdom EH9 1PR
EDINA is the Jisc-designated national data centre at the University of Edinburgh.
