Aerial Archaeology in Ireland - The Heritage Council

Enhancing the Archaeological Record
The technical limitations — as well as the merits — of the few collections of aerial photography that are routinely consulted in
Ireland are widely recognised. Although users of air photography are generally well aware that intensive reviews of existing sources
of aerial photographs and new reconnaissance can lead to new discoveries, there seems to be less awareness of quite how much
difference well-formulated projects of this type can make. This has been demonstrated by several different studies in Ireland.
• From a review of existing vertical photography, Hartwell (1987) reported discovering 60 new sites of all types within
an area of 40km 2 (500% increase on previously known 15 sites).
• From new oblique reconnaissance, Barrett (1990, 1995b) reported discovering 106 new cropmark sites within an area
of 900km 2 (330% increase on previously known 32 sites).
• From new medium-altitude vertical photography, Doody (2001) reported discovering 1,074 new sites of all types within
an area of 533km 2 (69% increase on previously known 1,490 sites).
• From new oblique reconnaissance, Power (1993) reported discovering 200 new cropmark sites within an area of approx.
256km 2 (increase not quantified).
• From his survey of coastal promontory forts, Casey (2001, 2002, 2003) has reported that out of a total of 408 sites
recorded, 199 were known already, while 90 were definite new ones (an increase of 45%). A further 119 possible
examples were noted that at the time of reporting still needed checking on the ground (possible total increase of
105%). This does not include other types of site.
• Shell and Roughley (2004) have reported that previously recorded sites account for only 10% of the length of features
transcribed from their lidar survey of the already well-surveyed Loughcrew area. Although much of this relates to
ancient field boundaries rather than individual monuments, the newly identified archaeology includes 13 small round
mounds, three larger mounds, five circular or sub-circular banks, a moated site, and a tripling of the number of square
enclosures from two to six.
• At Mullaghfarna, from a starting point of 47 house sites and other features identified in 1911, Grogan (1996) brought
the total to 82 identified from air photographs, with 60 recorded on the ground. New detailed photogrammetry and
fieldwork in 2004 (Stefan Bergh, conference presentation December 2005) identified a total of 153 sites and features
(an increase of 325% on the original survey).
In terms of research, the potential to enhance the archaeological record and pose new questions related to landscape interrelationships
has been rather better understood and embraced in a whole range of university-based research programmes and
the Discovery Programme (Section 4.2). The Heritage Council’s support for surveys by Markus Casey (2001, 2002, 2003) and Colin
Shell (Shell and Roughley 2004) also demonstrates their awareness of these issues.
But the overall strategic implications of such significant increases in known archaeology have yet to be fully translated into a
clear perception of how the strengths of aerial archaeology should be harnessed for wider understanding, conservation and
management of the archaeological resource.
Where this has been taken on board — as was the case for a number gas pipeline schemes from the 1980s onwards (Cleary et al.
1987; Gowen 1988), and as is now becoming more routine for infrastructure schemes — the value of the technique as a means
of identifying sites (and of reducing the risk of unexpected discoveries) is clearly recognised (Figure 36). It is also clear that some
of this reconnaissance not only identifies previously unknown sites, but can also reveal much more detail or greater extent of
those that are known. As the use of aerial archaeological surveys has become more routine for particular types of work, notably
road schemes, there is now great potential for a more detailed analysis of the extent and implications of the range and scale of
new discoveries, looking particularly at different types of archaeological remains in relation to terrain, soils and reconnaissance
methodologies.
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