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Early medieval Irish watermills

1: Introduction
2: Design
3: Chronology
4: Context
5: Conclusions
6: Bibliography
7: About the author


An examination of the role of watermill technology in the economic intensification of Early Medieval Ireland, with reference to recent advances in archaeologists’ understanding of their design, contexts of discovery and chronological development.

Reconstruction of a Medieval Irish horizontal watermill
Reconstruction of a medieval Irish horizontal watermill – Photo by Niall Roberts

Contrary to common opinion the economy of Early Medieval Ireland was reasonably advanced. During approximately 400 to 1000AD we see a gradual intensification of the broadly agricultural economy with a concentration in the seventh to ninth centuries (Kerr et al, 2013, p. 38). It is now thought that Ireland had a balance of both pastoral farming, focused on cattle; and arable farming focussed on barley (Edwards, 1990, p. 60). Throughout the Early Medieval period we also see interaction with places such as Gaul and the Mediterranean indicated by the discovery of foreign pottery types in Ireland (Kerr et al, 2013, p. 38). Therefore in the Irish economy at this time was both developed, in terms of its farming techniques and also because of its trading connections.

This essay will discuss how the use of Early Irish watermills has developed our understanding of their economy with particular reference to recent excavations, as these have been extremely useful in providing new information (due to an improvement of scientific techniques) that previous excavations have not. This can be split into three parts: the designs of watermills, of which there were several; their origins and chronological development; and finally the context of watermills, for example the landscape they sit in and who they belonged to.


In order to appreciate the significant impact of new sites in our understanding of watermills and the Early Medieval Irish economy we must first put them into context by discussing previous archaeological work and documentary sources.

Traditionally both the documentary and archaeological evidence has suggested that cattle farming was the focus of the agricultural economy in Ireland (Edwards, 1990, p. 60). Documentary evidence, because it details amount of transactions regarding cattle and occasionally other livestock; and archaeological evidence because animal bone is far more easily and extensively recovered than evidence of arable farming which could sometimes only be identified by the survival of quern stones and sampling for palaeobotanical remains (Edwards, 1990, p. 60).

However, more in depth studies of the documentary evidence and evidence from new sites (which will be dealt with separately below) have now changed our understanding of Ireland’s predominantly agricultural economy. We can see that several documents mention technology such as ploughs and mills (Edwards, 1990, p. 60). These suggest that agriculture was not as pastoral as previously thought, and that arable farming also played a significant role in the agricultural economy (Ó Cróinin, 1995, p. 99). Furthermore, the study of legal documents dating to this period in Ireland has revealed that mills were widespread enough to require specific laws by the end of the sixth century for example Senchas Mór, a text dating to around the year 600AD (Lucas, 2006, p. 79). An eight century document called Crith Gablach also shows us that people of all social classes could either own or joint-own a mill (Lucas, 2006, p. 79).


Whilst Irish mills have been excavated since the Victorian age it is new sites that give us a far better understanding of the arable side of Ireland’s agricultural economy and its intensification (Rynne, 1989, p. 21). The development of environmental archaeology enables us to recover much more information from mill sites, such as the ability to recover seeds and charcoal through the use of flotation and sieving, allowing us to date sites as well as pollen analysis that can be used to understand the type of environment mills were set in (Edwards, 1990, p. 60).

Furthermore, the preservation of many watermill sites is inherently good, as the water once used to power the mill now preserves the timbers. This allows us to date these sites more easily and accurately now, with the advances in carbon 14 dating and the completion of the master sequence for dendrochronology in Early Medieval Ireland (largely thanks to these waterlogged mill sites) (Edwards, 1990, p. 52).

Therefore we can see that with the advances in archaeological techniques both in dating and analysing, new sites in which samples can be recovered are massively useful in developing our understanding of the arable part of agriculture and therefore the economy of Early Medieval Ireland. This will be further investigated and illustrated below under the categories of the design, chronology and contexts of watermills in Ireland.