Aerial Archaeology in Ireland - The Heritage Council

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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. 69
70 Figure 36: Newly identified cropmark sites at Oldtown, Co. Laois, photographed in August 2001 at the route selection stage of the M7 Portlaoise– Castletown/M8 Portlaoise–Cullahill motorway scheme in response to the outbreak of foot-and-mouth disease. The motorway scheme was subsequently redesigned to avoid the cropmarks (Margaret Gowen & Co. Ltd, courtesy of the NRA) However, the implications of enhancing the archaeological record to inform the management of pressures of land-use change at a more strategic level (e.g. in relation to agriculture, forestry, housing and minerals) is still in its infancy. There is increasingly clear evidence that existing knowledge is very partial. The problem is that there is insufficient institutional recognition that policies and programmes of cost-effective, strategic aerial reconnaissance and mapping should be formulated and implemented. Recognition of this issue may have been inhibited by a number of negative factors which relate to the absence of information, and hence to a lack of clear rationale for action. These include: • Undue complacency about the supposed completeness of older archival sources (GSI, OSi CUCAP) in revealing what there is to be recorded from air photography. • Lack of appreciation of the capriciousness of technical seasonal and land-use factors in dictating whether or not archaeological remains are revealed by aerial imagery. • Previous lack of attempts to synthesise the well-documented and published data for the ‘yield’ of air photographic review and reconnaissance to bolster anecdotal awareness of its value as a means of enhancing the record. • Lack of data about what archaeology has been destroyed because it had not been identified and recorded from air photography, or was mistakenly classified as ‘destroyed’ in the SMR because it was only discernible from air photography. The process of ensuring that the results of air photography are reported and properly recorded is increasingly important, but it does not fall within the definition of an ‘archaeological object’ which must by law be reported under the National Monuments Acts. A clearer best practice obligation on practitioners to report the discovery of sites, not just objects and results of excavation, would help ensure that the public record is enhanced. Making this a requirement for all reconnaissance funded by public bodies or for public works would help.
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A I R A N D E A R T H A E R I A L A
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© An Chomhairle Oidhreachta / The
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3.9 Integration with other Types of
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Figure 14: The Discovery Programme
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Figure 39: This vertical photograph
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10 Foreword One of the initiatives
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12 Acknowledgements It would not ha
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14 Key Priorities for Aerial Archae
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16 • A practical handbook in arch
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Page 23 and 24: 22 As a means of discovering archae
Page 25 and 26: 24 Drawing on the work of O.G.S. Cr
Page 27 and 28: 26 2 PRINCIPAL SOURCES OF AIR PHOTO
Page 29 and 30: 28 National Museum of Ireland While
Page 31 and 32: 30 Other material held by the GSI i
Page 33 and 34: 32 Figure 9: An infrared vertical i
Page 35 and 36: 34 The aims and objectives of these
Page 37 and 38: 36 2.5 Private Collections Dr Daphn
Page 39 and 40: 38 2.6 Commercial Collections Two w
Page 41 and 42: 40 Figure 18: Google Earth satellit
Page 43 and 44: 42 3.2 Aerial Platforms The equipme
Page 45 and 46: 44 Figures 20 a-b: The use of ballo
Page 47 and 48: 46 Figure 23: The true form of the
Page 49 and 50: 48 Figure 25: The cumulative impact
Page 51 and 52: 50 3.4 Conventional Photography: Di
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Page 55 and 56: 54 Metrical Survey As Doody observe
Page 57 and 58: 56 shoreline and topography (ground
Page 59 and 60: 58 The fieldwork showed that the ge
Page 61 and 62: 60 Sonar Bathymetry Although there
Page 63 and 64: 62 Both Kelleher (1995) and Redfern
Page 65 and 66: 64 Interpreting Chronology and Sequ
Page 67 and 68: 66 While the Archaeological Survey
Page 69: 68 County No. Ringforts No. identif
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Page 75 and 76: 74 Roles and potential for historic
Page 77 and 78: 76 4.2 Roles in Supporting Archaeol
Page 79 and 80: 78 Figures 41 a-b: Gillian Barrett
Page 81 and 82: 80 The Archaeology of Lakes, Coast
Page 83 and 84: 82 Whole Landscape Approaches Perha
Page 85 and 86: 84 Figure 45: Drumlin landscape nea
Page 87 and 88: 86 Roads The National Roads Authori
Page 89 and 90: 88 Pipelines The general principles
Page 91 and 92: 90 General Development Where there
Page 93 and 94: 92 ‘…numerous sites in pasture
Page 95 and 96: 94 • • Earthen monuments are co
Page 97 and 98: 96 Designed Landscapes and Conserva
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Page 101 and 102: 100 Figure 55: Aerial photograph of
Page 103 and 104: 102 5 QUALITY, RESOURCES AND ORGANI
Page 105 and 106: 104 Estimates of costs per site or
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Page 109 and 110: 108 6 TEACHING AND TRAINING 6.1 Cov
Page 111 and 112: 110 6.2 Other Provisions for Traini
Page 113 and 114: 112 Benson, D and Miles, D 1974. Th
Page 115 and 116: 114 Doody, M G, 1995. ‘Ballyhoura
Page 117 and 118: 116 Twohig and M. Ronayne (eds) Pas
Page 119 and 120: 118 Raftery, J, 1951. Prehistoric I
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120 Colin Shell Cambridge Universit
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