Late Devensian glaciation and its influence on medieval urban development in the Irish Midlands
Co-Supervisors: Dr Francis Ludlow, Associate Professor of Medieval Environmental History at Trinity College Dublin & Dr Mark Hennessy, Assistant Professor of Geography at Trinity College Dublin.
Introduction:
This research topic was chosen while investigating the extraordinary resistance to urbanisation from the Gaelic inhabitants of Ireland during the early medieval period (c.400-1100 CE), something not satisfactorily explained in scholarship to date. In seeking to address this gap, and explain the longevity of this cultural phenomenon, my studies turned to its environmental context. It is this project’s central hypothesis that the pronounced resistance to early medieval urbanisation amongst the Gaelic Irish, and those arguable exceptions such as at Clonmacnoise, has substantial roots in the legacy of Late Devensian glaciation, which in its erosive and depositional effects, has exercised a strong control on the topography and agricultural potential of large areas of Ireland.
During the literature review, it became clear that while individual causations were highlighted (e.g., glacial eskers as fording points on the Shannon), the broader correlation between early medieval urbanity and glacial formations has not been thoroughly investigated. Of course, work connecting environment and early medieval settlement has been done before.[1] In contrast, this project will use GIS (Geographical Information Systems) software and focus on the digitization and spatializing of archaeological basal layer depth (ABD) in addition to non-urban archaeological settlement data already available in spatial format (e.g., crannog and ringfort locations). The ABD represents a measure of the depth of material in an area due to human occupation. Therefore, a greater ABD is indicative of longer lasting and more intensive settlement of an area, like that found at urban or proto-urban centres.
As stated by Victoria McAlister in 2023, little work has used GIS to further our understanding of early medieval Irish settlement, and the field is ripe for the application of this technology.[2] In an attempt to remedy this, and building on recent work on Ireland’s glacial past project will examine the Irish Midlands to test the legacy of glaciation’s effect on early medieval urban development relative to the other settlement types.[3]
Methodology:
This project will use GIS software to examine the relationship between glacial landscape features and the ABD at early medieval sites in the Irish Midlands. The utility of GIS in this scenario is its ability to integrate environmental and human data, which can be layered over each other to identify spatial correlations that remain hidden in other methods of analysis.[1]
Glacial landform data will be mainly drawn from the BRITICE Glacial Map V2.0, while the ABD values will be drawn from archaeological reports. These reports will be accessed through NRA Monographs and a request submitted to Transport Infrastructure Ireland in advance of the research period. The research supervisor will aid in accessing these NRA Monographs and will provide introductions to experts in this field. To complement the above data, the project will also employ freely accessible bedrock and soil type data from the Geological Survey of Ireland, Teagasc and the EPA, alongside diverse settlement data from the National Monuments Service (archaeology.ie).
The Irish Midlands was chosen because it was heavily affected by the late Devensian glaciation, with effects here studied extensively.[2] In addition to being well-defined in scholarship, the region’ size is manageable within the project’s timeframe. This region contains the largest proposed proto-urban settlement in early medieval Ireland, the ‘monastic town’ of Clonmacnoise. Including Clonmacnoise in the sample region provides an opportunity for comparison between a proto-urban site and its diversely settled but non-urbanised hinterland.
By utilising data in new ways, analysing the resulting maps, and addressing the project’s research questions, this project will contribute to our understanding of early medieval settlements, why they were situated in particular places, if this place had specific positive physical traits, and allow us a greater understanding of the Gaelic Irish settlement culture that lasted throughout the medieval period.
[1] James Connolly and Mark Lake, Geographical Systems in Archaeology, (Cambridge: Cambridge University Press, 2006.
[2] For Catherine Delaney’s recent work on glaciation in the Irish Midlands see; Catherine Delaney, ‘’The development and impact of an ice-contact proglacial lake during the Last Glacial Termination, Palaeolake Riada, central Ireland’’ Journal of Quaternary Science 37, Issue 8 (November 2022): 1422-1441, and Delaney et al, ‘’Irish Ice Sheet dynamics during deglaciation of the central Irish Midlands: Evidence of ice streaming and surging from airborne LiDAR’’ Geomorphology 306, Issue 1 (April 2018): 235-253.
[3] See; Aidan O’Sullivan, ‘’The Social and Ideological Role of Crannógs in Early Medieval Ireland’’ (PhD diss., National University of Ireland Maynooth, 2004), and Legg & Taylor, ‘’Modelling Environmental Influences on the locations of Irish early Medieval Rigforts,’’ Geoarchaeology 21, Issue 3 (March 2006): 201-220.
[4] Victoria McAlister, ‘’What Is Lost Can Be Found: History and Geographical Information Systems as Tools for Identifying Deserted Medieval Rural Settlement,’’ in Rethinking Medieval Ireland and Beyond: Lifecycles, Landscapes and Settlements, eds. Victoria L. McAlister and Linda Shine (Leiden: Koninklijke Brill, 2023), 213.
[5] For information on BRITICE see; Clark et al, ‘’Growth and retreat of the last British–Irish Ice Sheet, 31 000 to 15 000 years ago: the BRITICE-CHRONO reconstruction’’, Boreas 51, Issue 4 (October 2022): 699-758.
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