Aerial Archaeology in Ireland - The Heritage Council

Figure 33: Pits or mounds? A pair of probable round barrows enclosed by an elliptical ditch with other possible ring ditches nearby, forming part of a
Bronze Age funerary landscape at Chapelstown, Co. Carlow (Gillian Barrett, July 1989)
There has been considerable debate over the years about the classification of site morphologies as interpreted from aerial
photography. In Ireland, Barrett has consistently challenged over-simplistic classifications of ringforts that do not take account
of the complexities that can be revealed by cropmarks — raising a basic point about whether any earthwork form can be
regarded as complete. Monk (1989) recommended adoption of the English MORPH classification system (Edis et al. 1989), and
this was taken up by Kelleher (1995). Nevertheless, it has remained controversial, and Barrett (1995) considered the application
of a sophisticated system of morphological mapping and classification during the early years of the River Barrow aerial survey
project to be inappropriate. Instead, a simple morphological classification was adopted which provided an initial summarising
device and a preliminary sorting of the main categories of new cropmark discoveries. However, given the subsequent expansion
of aerial survey, the need for more progress in mapping and morphological assessment is now considered an important priority,
both for new photography and for the full evaluation of the CUCAP archive which remains an under-exploited resource in
Irish archaeology (Barrett 2002). While MORPH seeks to be objective, like all classificatory systems it does involve subjective
interpretation and choice. It has also been criticised for being too cumbersome in dealing with sites of any complexity.
Using the Rathcrogan complex, Redfern (1998, 2002) has explored the possibility of classifying sites digitally by using
pattern recognition techniques based on defined parameters as part of a software package that provides rectification, image
enhancement and terrain modelling. He compared the digital classification to standard classes used by the County Inventories
and found reasonably good correlation. The use of pre-determined digital recognition parameters offers potential to make
the approach more objective than traditional archaeological judgement, but its interpretive value has yet to be tested fully. In
general, morphological classification is not seen as a high priority compared with clarifying other issues of form and sequence
in complex sites.
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