At present more than 1,600 toghers (wooden trackways) or parts of toghers are mapped in the Irish SMR, however the wet and uneven ground surface of the Irish bogs have long posed a challenge to the prospection of these landscapes using archaeological geophysical methods. The function and morphology of trackways also impede meaningful assessments. While many trackways can be used as access routes between drier, higher lands, others terminate within a bog for no apparent reason. In other cases, isolated platforms exist, the function of which have not been determined. It is therefore difficult to anticipate, model or predict where a wooden trackway may be located within a bog, as linking archaeological or natural dryland sites is not necessarily their function.
Some geophysical techniques are appropriate to the study of palaeoenvironments and wooden structures. Electromagnetic and induced polarisation methods have been applied at Edercloon, Co. Longford, a large wooden trackway complex, in an attempt to map some of the known trackways beyond an excavation cutting. Many of the Edercloon trackways were shown to abut and cross over and beneath each other, increasing the complexity of identifying specific or groups of specific features using geophysical methods. A semi3D inversion of induced polarisation data demonstrated that distinctive trackway derived anomalies could be clearly traced, mapping at least three known Late Bronze Age and Iron Age trackways which continued across the survey area beyond the excavation, increasing the known length of one of the tracks by 19m. The use of induced polarisation and its application to wider areas of study is discussed in light of these results.

Location

Norcroft Centre, University of Bradford