Aerial Archaeology in Ireland - The Heritage Council

to suit their purposes. Most examples contain both distribution maps and/or interpretive plots, as well as reproductions of the
photographs themselves, at least on a selective basis.
An area that has received less attention (at least until recently) is the consideration and analysis of the whole historic
environment — and the history of landscape change — rather than just picking out relict features. For example, in a report for
Teagasc, Kavanagh (2002) reviewed the effectiveness of the REPS scheme in relation to the survival and discovery of individual
monuments and more general landscape ‘quality,’ but not the wider historic character of the landscape. Where the wider historic
landscape character has been addressed effectively, it is often the richness of the photographs themselves that most clearly
illustrates the detailed complexity of the rural historic environment and the insidiousness of pressure of change (e.g. Barrett
1997b; 1997/8; Dunford 2002, 2003).
Archiving
The practice of duplicating sets of aerial photographic material (e.g. NMS copies of photos from CUCAP, OSi, Air Corps, GSI and
other sources; National Museum set of CUCAP photos and some other sources) means that much relevant photography is not
reliant on its survival for a single source — at least in terms of prints. Moreover, public archives with original material have good
storage conditions on the whole.
More problems arise with valuable private collections which are available for consultation but not yet fully assessed for their
content. There would clearly be merit in duplicate sets of prints being available (subject to copyright restrictions and rights), both
for the security of the information they contain and for easier consultation.
The growing use of digital imagery and remote sensing techniques poses particular challenges for long-term archiving. The
Archaeology Data Service in Britain has published a guide to good practice (Bewley et al. 1998). 23
5.2 Cost-effectiveness, Resources and Co-ordination
In very general terms, the cost-effectiveness of aerial archaeology is widely recognised (e.g. Wilson 2001; British Academy 2002).
It is not easy to estimate the totality of aerial archaeology carried out in Ireland — not least because a considerable amount
of reviewing and plotting of existing photography is done on a case-by-case basis. In any case, this is not the best measure of
whether it is used effectively.
Johnson (1998) has noted the value of analysing existing photographic archives, observing:
‘Kelleher (1995) reported a high success rate in identifying previously unrecorded sites through the use
of computer enhancement and mapping programmes to analyse aerial photographs. The results were
particularly impressive in identifying field systems and associated enclosures in marginal areas.’
In terms of reconnaissance for oblique photography, the cost-effectiveness of the technique can be gauged on the basis of ‘yield’
of results per flying time or the approximate cost per new discovery. In the exceptional year of 1989, Barrett (1995b) recorded
137 sites in six hours’ flying along the Barrow Valley between Monasterevin and Bagnelstown. Power (1993) records that over
200 previously unrecorded sites were discovered in just six hours’ flying in the area between Fermoy and Mallow along the
Blackwater Valley (c. 20 miles x 5 miles). However, Power also notes that this was highly exceptional. Otherwise, over ten years,
the Cork Archaeological Survey undertook 40 hours’ flying, recording previously unknown sites at around one or two per hour.
Power observed that
‘…this discovery rate compares very unfavourably with the returns from actual fieldwork — especially in
the less intensively farmed parts of the county. The return is even less productive when one considers that
those sites not revealed by cropmarks still have to be visited on the ground…’
23 http://ads.ahds.ac.uk/project/goodguides/adandrs/
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