Aerial Archaeology in Ireland - The Heritage Council

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Roles and potential for historic townscape and landscape assessment
Historic landscape and townscape characterisation is an emerging approach which aims at a more holistic conservation of the
historic environment in Ireland, as it is in Britain and other parts of Europe (Fairclough and Rippon 2002). The traditional — and
still predominant — approach to heritage conservation has been through the identification and protection of single sites or
features. Approaches based on characterisation seek to take a more holistic view. These recognise that the historic character
of places (much of which is perceived and valued intuitively rather than consciously) cannot be identified adequately through
single scattered features. Instead, it relies more heavily on long-term patterns of how people have used and adapted an area to
suit their needs, sometimes powerfully reflecting differences in social status and local political power (Figure 39).
As indicated below, there is a need to do more to develop concepts and methods of applying aerial imagery more directly to
understanding and characterising landscape change than can readily be done through the traditional approaches based on the
concept of using archaeological ‘sites’ as the main building blocks of research and heritage management. In a sense, this concept
is not new — it has already been explored by Swan (1983, 1985), Barrett (1992, 1995a, 1997b, 1997/8, 1999) and Kelleher (1995).
However, new technologies (better rectification and terrain modelling, satellite imagery, lidar, GIS) coupled with concepts of
historic landscape characterisation offer opportunities for taking this much further.
Mapping and Interpretation
The current policy at NMS is to ensure that the basic air photographic information, together with an interpretive sketch plot,
is included in the SMR files along with descriptions, drawings and ground-level photography. This has been a pragmatic way
of ensuring access to the aerial photographic data, with a minimum need for additional staff resources spent on plotting and
mapping, and physical storage of mapping.
Apart from having been cost-effective in the compilation of the SMR and Inventories, this approach has a number of advantages.
Through the SMR files, the air photographic evidence is integrated with other data. Prints of the photographs are directly
available, as is an interpretive plot (rather than relying more on secondary interpretive plotting). Disadvantages are that, while
there are cross-references within the record, there is little overall mapping of complex areas. The danger here is that evidence of
context and relationships with other sites might be neglected. This is especially relevant for strategic assessments of land-use
policy and development. As the NMS points out, under the National Monuments Acts 1930-2004, the SMR is (and must be) ‘a
list of known and potential monuments; it is not, nor is it intended to be, a list of contextualised landscapes’. This, of course, does
not preclude the development of other non-statutory interpretative mapping, characterisation and other elements (e.g. Figure
40). Indeed, with modern methods, the inclusion of layers within the NMS/GIS system which provides ortho-photography and
other basic geographical data can already provide important elements.
Such presentations help to provide basic transcriptions and approximate locations for sites within their landscape context.
Modern GIS methods offer more sophisticated digital techniques that can amalgamate different data sets and provide more
accurate, higher resolution plotting, but they still rely on conceptual clarity of analysis and presentation.
As the data from the Record of Monuments and Places becomes available online 16 (temporarily withdrawn for correction at
time of writing), there is at least potential to make aerial imagery more available. Ongoing scanning of photographs in the
archive for incorporation into the NMS/GIS also offers potential for digital enhancement and rectification. This could provide a
wider professional and public access to a map-based presentation of aerial photographic evidence.
Users say they would like to see more interpretive mapping by experienced personnel, while also having access to original
material. This recognises that the interpretation and plotting of air photography are real skills. It also acknowledges that the
subtleties of what can be seen on air photographs are such that their simplification into map form is always highly interpretive
and therefore seldom completely definitive. Moreover, fieldwork (especially geophysics or excavation) can often lead to the
discovery of additional evidence that modifies original interpretations.
16 http://heritagedata.ie/en/index.html