2004:1137 - BELDERRIG BEG/BELDERRIG MORE/GLENULRA, Mayo

Archaeological environmental research investigations were carried out in July 2004 at the Céide Fields, near Belderrig, north-west Co. Mayo, in Belderrig Beg (Area 1), Belderrig More (Area 2) and Glenulra (Area 3) townlands and in the Céide Fields (Area 5). The aim of the excavation was to investigate prehistoric land use and management, centred around the Neolithic landscape of the Céide Fields, using a range of geo-archaeological techniques. Excavation of a number of test-pits was undertaken to collect environmental samples of pre-bog buried soils for scientific analysis. This project was conceived and headed up by Dr Erika Guttmann, Environmental Archaeologist, University of Reading, and the work is fully funded by the Department of Archaeology, University of Reading. In consultation with the National Monuments section of the Department of the Environment, Heritage and Local Government, an excavation licence was applied for and issued to Paul Stevens.

Background
The intensity of agricultural production in Neolithic Ireland is the key research issue addressed in this project. Early arable agriculture in Britain and Ireland was once thought to have taken place in small fields in temporary clearings, but subsequent models suggested that Neolithic populations were more sedentary. The nature of Neolithic settlement and subsistence has again been radically reconsidered (Thomas 1991; Whittle 1996), but the argument for shifting and impermanent settlement is largely based on the absence of evidence in southern England. The Scottish and Irish evidence strongly contrasts with this model; in Co. Mayo there is extensive evidence of Neolithic field systems sealed beneath blanket bog (Caulfield et al. 1998), and pollen analysis has demonstrated the presence of cereal pollen in a cleared landscape from the Early Neolithic period (O'Connell and Molloy 2001). Ard marks and stone ard shares within the fields also demonstrate that they were partly used for arable production. The creation of field systems in itself suggests intensive land use, but production can be increased by adding fertilisers and further increased by improving the quality of the fertilisers. At present there are two contrasting models for Neolithic agriculture in Europe: arable land on the Continent has been intensively fertilised with animal manures since Neolithic times, but in Britain both Neolithic and Bronze Age soils appear to have been fertilised using only domestic waste, a much less intensive system suggesting less intensive or less formalised stock-keeping (Guttmann et al. 2005). The extensive field system suggests that agricultural production in Neolithic Ireland may have been as intensive as production on the Continent. This model is radically different from the one suggested by Thomas (1991) for southern England. This research is especially timely because of the recent radiocarbon dating programme of the field systems (Caulfield et al. 1998). The dating of the fields was not disputed when it was first published in 1978, but later reinterpretation of the Neolithic period as a time of mobility led some researchers to suggest that the early dates were questionable. Radiocarbon dates were taken from pine stumps in the peat overlying the mineral soil within the fields, and these dates have now unambiguously established the Neolithic dates of the fields.

Methodology
Ten test-pits were excavated in four areas, numbered Areas 1–3 and Area 5. The laboratory analysis will take place over the next several months and the results of this work are not yet available. The aim is to compare the anthropogenic inclusions and geochemical signatures of the buried soils in areas which were cultivated for arable production in prehistory with areas which are thought to have been used for pasture (Areas 2 and 5). Both arable and pastureland will be compared to uncultivated prehistoric analogues (Areas 3 and 4) where it has been demonstrated that there is a buried land surface beneath the peat, but where there are no archaeological features. This will provide control; i.e. a yardstick against which to establish what is 'enhanced' and what is not.

Neolithic and Bronze Age soils were sampled in order to identify fertilising materials and to see whether there were changes in the manuring strategy over time. Thin section and bulk samples were taken from pre-peat mineral horizons with and without ard marks, for comparison. Control samples were taken from buried soils within the field systems. Laboratory analysis is currently under way and soil micromorphology will be used to identify cultural material such as bone fragments, charcoal and charred peat. Soil lipids will be extracted from bulk samples and analysed (with replicates) in order to identify and distinguish any animal manures present in the soil. Samples for organic/inorganic phosphate analysis will be analysed at the University of Reading and correlated with the results of the lipid analysis to test whether enhanced levels of organic phosphate are reflecting added organic manures (Linderholm 1997). Soil magnetism (mass susceptibility, Xfd, ARM, IRM) will be analysed in order to identify fuel ash residues, which have been added to the soil, and to distinguish the signatures in different areas (e.g. Peters et al. 2001).

Results
Buried mineral soils with a thickness of between 40mm and 190mm were discovered in all of the excavated test-pits. Interestingly, the soils in the control test-pits, where cultivation did not take place, were the thinnest. The soils measured 40mm in depth in both Areas 1 and 3; this suggests that soils within the field system were preserved and may possibly have been artificially aggraded. Alternatively, it may be that the soils outside the fields have been truncated, possibly by peat extraction in prehistory. This is something that can be addressed using thin section analysis. Only one soil horizon was discovered in all of the test-pits except H and I, which had upper horizons of 90mm and 60mm (respectively) and lower horizons of 100mm. It is worth mentioning that the layer of black, moderately well humified peat that overlay most of the buried soils was not apparent in some test-pits, which indicates that the buried soils in these pits may have been truncated. A thin section tin was placed across the boundary between the buried soil and overlying peat layer in all of the test-pits apart from one, and the analysis should clarify whether or not there was any truncation.

References
Caulfield, S., O'Donnell, R.G. and Mitchell, P.I. 1998 14C dating of a Neolithic field system at Céide Fields, County Mayo, Ireland. Radiocarbon 40(1–2), 629–40.
Guttmann, E.B., Simpson, I.A. and Davidson, D.A. (2005) Manuring practices in antiquity: a review of the evidence. In M. Brickley and D. Smith, Fertile ground: papers in honour of Susan Limbrey. Oxbow Books.
Linderholm, J. 1997 Prehistoric land management and cultivation: a soil chemical study. Bulletin 1 of the Archaeological Soil Micromorphology Working Group. London.
O'Connell, K. and Molloy, M. 2001 Farming and woodland dynamics in Ireland during the Neolithic. In Biology and environment: proceedings of the Royal Irish Academy 101B, 1–2, 99–128.
Peters, C., Church, M.J. and Mitchell, C. 2001 Investigation of domestic fuel sources on Lewis using mineral magnetism. Archaeological Prospection 8, 227–37.
Thomas, J. 1991 Rethinking the Neolithic. Cambridge. Whittle, A. 1996 When did Neolithic farmers settle down? British Archaeology 16(7).