Palaeohydrology and archaeology in raised mires : a case study from Kilnagarnagh
This thesis concerns the palaeohydrological reconstruction of a raised mire in Kilnagamagh, Co. Offaly, Ireland in order to investigate environmental influences on human activity in mires as represented by archaeological deposits, and the mire's potential for broader palaeoenviromnental reconstruction. The results are compared against trends in other mires in Ireland, the UK and Northwest Europe. Analytical techniques used include gross peat stratigraphic and archaeological field survey, testate amoebae, plant macrofossil and colorimetric humification analyses and radiocarbon dating. A Bronze Age wooden walkway in Kilnagarnagh Bog and a series of trackways from neighbouring bogs provide the archaeological focus of this study. It is shown that trackway construction, or the lack thereof, may be viewed in part as a response to changes in the environment. Very dry or very wet situations may not warrant trackway construction; however, simple models of behaviour occurring in either wet or dry situations may be misleading as local environmental conditions may be more complex. Some models of peatland development typically suggest that external (allogenic) factors such as climate change control development. Others suggest that both external and internal (autogenic) processes combine to control development. In reconstructing environmental conditions it is important to separate these controls as this has implications for the use of peatland development as a proxy for climatic reconstruction. The timing of the most significant hydrological changes in KiInagarnagh suggests autogenic factors rather than regional climate change controlled development, with one exception; from c.850BC to around the seventh century AD mire growth was greatly retarded due to a sudden and long-term drop in the water table which may ultimately have been driven by a regional change to wetter conditions.