Planning Uncertainty: Creating an Artefact Density Index for North Yorkshire, England

Nick Boldrini

Heritage Unit, County Hall, Northallerton DL7 8AH, UK

Cite this as: Boldrini, N. 2006 Planning Uncertainty: Creating an Artefact Density Index for North Yorkshire, England, Internet Archaeology 21.


Portable antiquities (sometimes known as small finds or chance finds) are often recorded within most Historic Environment Records to a spurious level of precision. For example, finds located only within a parish, or general area, are often mapped within GIS systems to exact points. Similarly, finds known only to the nearest kilometre square are usually mapped in the bottom left-hand corner of the square in GIS. While such mappings can be taken into account to some extent when trying to assess the archaeological potential of an area, the degree to which the records may give distorted views of the archaeological potential of an area may not be fully appreciated. This may mean that the full archaeological impacts of development may not be taken into account during development control decision making.

This article looks at an alternative method for mapping such finds in order to produce an Artefact Density Index for areas, which more usefully reflects the pattern of activities across the landscape. The Artefact Density Index (ADI) was divided to reflect broad archaeological periods (e.g. Roman, medieval etc.), as well as broad artefact types (e.g. weapons, tools etc.). The ADI was based on combining weighted values for finds types, with the weight reflecting the precision of the location of the finds (i.e. finds recorded only at parish level will be given less weight than those recorded more precisely). An ADI was developed for a sub-area of the North Yorkshire County Council HER area, and also incorporated data from the Portable Antiquities scheme as a case study for the project.

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