Environmental Archaeology in Ireland

By Eileen M. Murphy and Nicki J. Whitehouse

This edited volume of 16 papers provides an introduction to the techniques and methodologies, approaches and potential of environmental archaeology within Ireland. Each of the 16 invited contributions focuses on a particular aspect of environmental archaeology and include such specialist areas as radiocarbon dating, dendrochronology, palaeoentomology, human osteoarchaeology, palynology and geoarchaeology, thereby providing a comprehensive overview of environmental archaeology within an Irish context. The inclusion of pertinent case studies within each chapter will heighten awareness of the profusion of high standard environmental archaeological research that is currently being undertaken on Irish material. The book will provide a key text for students and practitioners of archaeology, archaeological science and palaeoecology.

• Language: English
• Publisher: Oxbow Books
• Release date: Oct 10, 2007
• ISBN: 9781782974789

Book preview

Introduction

Eileen M. Murphy and Nicki J. Whitehouse

Environmental archaeology in Ireland has a long history of research which dates as far back as the seventeenth century to the deliberations of Molyneaux (1697) on the Giant Irish Deer and megafaunal extinctions. Throughout the nineteenth and first half of the twentieth centuries a certain amount of research was undertaken on a variety of remains in Ireland that we would now consider to fall under the auspices of environmental archaeology–human remains (e.g. Frazer 1890–91; Martin 1935), faunal remains (e.g. Wilde 1840; 1857–61), shellfish (e.g. Brunicardi 1914, 208), plant macro-remains (e.g. Jessen and Helbaek 1944; Mitchell 1946) and pollen (e.g. Erdtman 1928; Jessen 1949). It is interesting, however, to note that some of the core aspects of environmental archaeology, including palaeoentomology (e.g. Coope et al. 1979; Kenward and Allison 1994) and wood and charcoal analysis (e.g. Mitchell 1986; 1989) have only been studied within an Irish context in relatively recent times. Clearly there is still much potential for new developments within Irish environmental archaeology, particularly in view of the recent upsurge in developer-funded archaeology which is revealing substantial deposits of environmental significance.

It is hoped that the current edited volume of 16 invited papers will be a testament to the healthy state of environmental archaeological research in Ireland at the beginning of the twenty-first century. The papers each focus on a particular aspect of environmental archaeology and include such specialist areas as radiocarbon dating, dendrochronology, palaeoentomology, human osteoarchaeology, palynology and geoarchaeology. Each contribution provides an introduction to the techniques and methodologies, approaches and potential of the different aspects of environmental archaeology currently being used within an Irish context. The researchers have all included pertinent case studies within their chapters that should heighten awareness of the profusion of high standard environmental archaeological research that is currently being undertaken on Irish material. In addition, each contributor has highlighted gaps in knowledge and made recommendations for potential ways forward for their aspects of the discipline; these insights should act as a valuable springboard for ideas and future projects. It is hoped that the book will provide a key text for students and practitioners of archaeology, archaeological science and palaeoecology and that it will serve as a baseline upon which future environmental archaeological studies within Ireland can be built.

The book is divided into five thematic sections–Dating, Humans and Animals, Plants, Approaches to Environmental Archaeology and Legislation. The first group of papers focus on three of the main scientific dating methods used by environmental archaeologists–radiocarbon dating, dendrochronology and tephrochronology. Phil Barratt and Paula Reimer begin their chapter with the statement: ‘Today it would be difficult to imagine archaeology without the availability of radiocarbon dating’. Never a truer word was said and this is reflected in the evidence for the extensive use of radiocarbon dates apparent throughout the volume. We are fortunate that Ireland is home to one of the leading high-precision radiocarbon laboratories in the world–the 14CHRONO Centre at Queen’s University Belfast–which is soon to house an Accelerator Mass Spectrometry (AMS) facility. The paper begins by providing an overview of the development of the radiocarbon dating technique since the 1940s. The principles and rationale behind the method are outlined and the differences between the Gas Proportional Counting, Liquid Scintillation Counting and AMS methodologies are discussed. The principles of fractionation correction and calibration are explained in addition to the age limitations and accuracy of the technique. Valuable guidelines as to how best to obtain optimum dating results are provided and practical advice is imparted concerning sample suitability, the storage and handling of samples and sample submission. Information is provided as to how the resultant raw dates should be calibrated and conveyed to a wider audience. The authors make the point that dating is of particular importance to environmental archaeologists investigating the impact of humans on a landscape that is changing on a range of temporal scales. They conclude by suggesting that more interaction between environmental archaeologists and radiocarbon laboratory personnel, with the exchange of ideas and advice at the outset of archaeological projects, will help aid in sample selection and the interpretation of results.

In Chapter 2, David Brown and Mike Baillie review the success rates with which dendrochronology can be applied in Irish wetland archaeological situations. They highlight some of the practicalities associated with this technique and the importance of completeness of samples with respect to sapwood as a limiting factor for dating precision and subsequent archaeological interpretation. In particular, they draw attention to the fact that it is necessary for archaeologists to strive to get the best and most refined dates possible for their sites, if they wish for the significance of their sites to fit into the wider context of archaeological sites. This will allow archaeologists to establish the relationship between precisely-dated environmental change and archaeological activity and what they term ‘the world of real chronology’ that is currently being developed by dendrochronologists and ice-core workers, among others. Brown and Baillie then provide a series of case studies where dendrochronology has been applied. In the first instance, they highlight the use of the technique in the study of Late and Post-Medieval house structures and sequences. Two case studies are provided: Rathfarnham Castle, Dublin, where dendrochronology was able to provide a precise chronology of the building of the castle and Cultra House, Co. Down, which illustrates the difficulties presented by the re-use of timbers. Finally, the authors focus on the significance of the Irish tree ring chronologies in helping to piece together new pictures of the Irish past, such as understanding of past environmental events and the relationship between ‘events’ identified in the tree ring record with societal change.

Keeping with the dating theme, Jon Pilcher draws attention to the valuable chronological and stratigraphic role tephrochronology can provide in the study of past environments, especially in north-west Europe where well-dated Icelandic tephras (volcanic ashes) can reach suitable preservational environments such as lakes and peat bogs. Visible tephra layers have been used extensively in the study of the early settlement of Iceland and the Faroe islands, but modern techniques now allow users to extract much smaller amounts of tephras (also known as micro-tephras), allowing the technique to be extended to Ireland, Britain and other parts of north-west Europe (see Turney et al. 2006). These improved concentration and detection methods now permit the use of these valuable chronological markers in a wide range of Quaternary deposits. Following a discussion of the practicalities of the technique, including sampling, extraction and analysis of geochemical data, Pilcher then discusses the various uses of tephra as a chronological and correlation tool and presents a case study where tephra was recently used in the study of environmental change in the Lafoten Islands off the coast of Norway, highlighting its ability to correlate episodes of environmental change across the North Atlantic region. There are some difficulties associated with the technique, however, not least the time-consuming nature of analysis and the uneven distribution of tephra; there can be considerable variation in the distribution of the tephra from even within the same lake basin and there are often problems associated with the similarity of tephra geochemistries (e.g. Pyne-O’Donnell 2006).

The second section of the book deals with humans and animals (mammals, birds, fish, shellfish and insects) and the role they have played in environmental archaeological studies within an Irish context. Eileen Murphy starts this part of the volume by providing a review of human osteoarchaeology in Ireland, starting with a brief history of the discipline, followed by an overview of the main methodologies employed in the general analysis of archaeological human skeletal remains. The second part of her paper provides an insight into why such analyses are important for furthering our understanding of the human past within an Irish context, focusing on a series of themes and case studies, including demography, health and disease (such as diffuse idiopathic skeletal hyperostosis, leprosy and tuberculosis), activity markers upon skeletons, diet and trauma. In particular, she draws attention to the importance of a adopting a biocultural approach, whereby the osteoarchaeological evidence is not studied in isolation but rather in conjunction with the historical and archaeological information relating to a particular site. By using such an approach it is possible, for example, to identify and interpret unusual populations, such as those in cilliní or ecclesiastical burial grounds. She concludes by indicating that human osteoarchaeology within Ireland is still progressing and there is great potential for the development of collaborative synthesis projects between specialists working on the island, as well as the opportunities offered by some of the specialised biomolecular techniques, such as aDNA and stable isotope analysis.

Finbar McCormick’s paper largely reviews the evidence that has emerged from the study of mammal bones from Irish prehistoric sites. Knowledge in this field has been greatly enhanced over the past four decades when archaeozoological remains began to be analysed on a more routine basis than before as a result of the pioneering research undertaken on the Newgrange faunal remains by Louise van Wijngaarden-Bakker (1974). He identifies how some gaps still remain to be filled, however, particularly for the Neolithic and Late Iron Age periods. He highlights how the more recent evidence has revealed significant errors in the understanding of prehistoric animal exploitation. Prior to 1970, it was assumed that the Mesolithic economy was largely based on coastal shellfish exploitation, for example, supplemented by fishing and hunting, particularly for Red Deer. It is now known that large oyster middens are more of a Neolithic phenomenon, while Red Deer appears to have been absent from Ireland during the Mesolithic, with wild pig forming the main component of the Mesolithic meat diet. McCormick reviews the evidence for animal exploitation from the Mesolithic through to the Iron Age period. He looks at the composition of the faunal assemblages available from settlement sites for each period as well as animal remains derived from ritual contexts. This data provides information concerning the species of animals that were being exploited and the economic form that this exploitation took. Such information can provide valuable insights concerning the nature of the environment that both the animals and humans inhabited throughout the prehistoric period. This would appear to be particularly true for the Late Bronze Age assemblage derived from the island site of Dún Aonghasa, Co. Galway, where unusually sheep/goat were found to have been predominant. It is considered probable that this situation may have arisen due to the harsh environment of Arran Island which would have been most suitable for grazing hardy sheep. This theory finds support in the evidence for an unusually high slaughter rate of young calves at the site which is thought to be an indication of fodder shortage and is a recognised characteristic of faunal assemblages derived from marginal Atlantic sites. McCormick concludes by stating that we are now in a position to prioritise areas of future research within Irish archaeozoological studies to help fill the gaps in knowledge. He makes reference to the use of genetic studies as a means of further developing our understanding of the origins and nature of the animals of prehistoric Ireland.

Sheila Hamilton-Dyer reviews the evidence derived from bird and fish remains recovered from historic period sites in Ireland. She makes the point that bird and fish remains have consistently formed a minor, but important, component of archaeological faunal assemblages. One of the main problems with bird and fish bone studies within Ireland has been related to a general lack of sieving on archaeological sites. Where this methodology has been employed it has become clear that fish, in particular, are being under-represented in Irish assemblages. The paper includes a valuable overview of methodological and taphonomic considerations and provides a clear justification as to why the study of archaeological bird and fish bone assemblages is of importance. This is followed by a detailed review of the evidence derived from bird bones and fish bones in two separate sections which each deal with sites dating from the Early Christian period through to Post-Medieval times. Despite the limitations highlighted in the earlier part of the paper, trends in consumption and exploitation are beginning to emerge. Early Christian coastal sites, such as those at Illaunloughan, Co. Kerry, and Doonloughan, Co. Galway, have revealed evidence for the exploitation of a large variety of local marine fish and birds. Irish urban Medieval centres, such as Dublin, thought to have undergone major influence from Anglo-Norman settlers, appear to provide the first evidence for the introduction of domestic fowl, geese and ducks. This is in direct contrast to sites located in areas outside Anglo-Norman influence where domestic birds occur in much smaller proportions. As was the case for archaeological mammal bones, Hamilton-Dyer is of the opinion that it is now possible to identify notable gaps in knowledge for the bird and fish bone record. For the historic period the evidence is particularly lacking for low status rural sites and inland sites in general. A notable aspect of all Irish fish bone assemblages is the presence of marine as opposed to freshwater species, a finding which remains to be satisfactorily explained. Another point of interest raised in the paper includes the discrepancies that exist between the documentary and archaeological records for bird and fish exploitation in historic Ireland, which clearly highlights the need for archaeologists to use documents as a source of information with caution. The paper concludes with a discussion of priorities for future research. Hamilton-Dyer is of the opinion that the study of the introduction and past distribution of bird and fish species is an area of much potential within an Irish context. Other aspects of research that she suggests could be developed include the application of DNA and metrical techniques to enable the identification of the various different goose and duck species and to gain a clearer understanding of physiological changes that may have been due to domestication and husbandry techniques. Furthermore, with the ever increasing body of archaeological bird and fish bone data from Ireland it is becoming possible to compare this information to that derived from Britain and other parts of Europe.

Shell middens are very well known sites within an Irish context and middens and molluscs form the topic of Emily Murray’s paper. She starts by introducing the nature of archaeological deposits which contain shellfish remains and highlights how their real value does not lie in the reconstruction of past diet but rather in the potential insights they can provide concerning wider aspects of a site’s function, culture, economy and environment. She highlights how early researchers had assumed the producers of shellfish middens relied on shellfish for the greater part of their sustenance and how they were the product of poor and primitive folk. Following on from this she points out that, despite developments in scientific techniques, understanding of Irish shell middens has only marginally progressed. The majority of the paper then focuses on attempting to address this issue by providing a detailed review of shellfish exploitation from Mesolithic through to Early Christian times. Material recovered from Late Mesolithic sites in Counties Dublin and Louth has indicated that a wide variety of shellfish, in particular oysters, periwinkles and carpet shells, were exploited by the people who used these temporary habitation sites. The exploitation of the coastal environment appears to have continued into the Neolithic period. One of the most interesting aspects of the Neolithic shell deposits is the presence of very large middens, largely comprising oysters, from certain parts of Ireland, including Ballysadare Bay, Co. Sligo. Murray is of the opinion that the occurrence of such middens is an indication that oysters were eaten in vast quantities by some during the Neolithic, and may be an indication that people reverted to a hunter-gatherer existence at least on occasion. Understanding of shellfish exploitation during the Bronze Age and Iron Age is less well understood, although excavation at Bronze Age sites such as False Bay, Co. Galway, and of Iron Age middens in Mannin Bay, Co. Galway, indicate there was at least some exploitation and settlement along the coast during these periods. Shellfish have been recovered from a variety of Early Christian period coastal sites, including Doonloughan, Co. Galway, as well as on inland sites and in Viking urban contexts, thereby suggesting that they were still of importance during historic times. The paper concludes with a discussion of the vulnerability of coastal midden sites, largely as a consequence of erosion, and stresses the value of intertidal surveys such as that recently undertaken in Strangford Lough, Co. Down (McErlean et al. 2002). The potential of material derived from excavated shell middens for the purposes of refining the accuracy of radiocarbon calibration of marine-derived materials is also highlighted.

Concluding the section on humans and animals Nicki Whitehouse provides a review of fossil insects in Irish environmental and archaeological investigations. She begins by outlining the history of the discipline and by highlighting the different insect groups that are available for analysis and how they can make a contribution to the understanding of past environments. The underlying principles and methodological issues concerning sampling, identification and the analysis of insect material are then discussed. The chapter proceeds with a comprehensive review of the available fossil insect evidence from Ireland, starting with the knowledge of climate change inferred from fossil insects. This work is important not just in terms of understanding past climates and how these would have impacted upon prehistoric populations, but also within the context of global climate change. Relatively little work has been undertaken on fossil insects from the early part of the Holocene, although recent work by the author on Later Mesolithic and more recent prehistoric sites, including Sluggan Bog, Co. Down, and Ballyarnet Lake, Co. Derry, has provided important new data on the development of the Irish landscape. The final section of the paper reviews the contribution of urban and rural archaeological insect faunas from historic period Ireland. An overview is provided of published research on Viking and Medieval deposits from Dublin and the results of study on a new Post-Medieval assemblage from Newmarket, also in Dublin. The results of the latter study indicate that living conditions at Newmarket were generally not salubrious. Specific finds of interest include the first identification of both the bedbug and oriental cockroach from an Irish archaeological context. The findings from these urban contexts are compared with those derived from the rural Early Christian rath site at Deer Park Farms, Co. Antrim, where waterlogging of the site resulted in extraordinary levels of preservation. The nature of the insect fauna suggested that foul material, probably derived from animals, had been left exposed on the living surfaces of the rath, while abundant human parasites were found associated with bedding structures. The paper concludes with a number of recommendations to help fossil insect studies develop within Ireland. Whitehouse is particularly of the opinion that further investigation of prehistoric settlement sites is necessary in addition to the training of new practitioners to undertake further research on Irish material.

The third part of the book focuses on the role of plant remains within Irish environmental archaeology. Michael Monk begins the section with a personal and archaeobotanical overview of environmental archaeology in Ireland. He reviews the development of the discipline, with particular reference to the study of plant remains, from the nineteenth century onwards. He also provides a survey of the development of environmental archaeological teaching within third level education. He believes that environmental archaeology was slower to take off in Ireland compared to Britain and discusses why this may have been the case. He is of the opinion that the situation arose as a result of a variety of factors, including a lack of emphasis on environmental archaeology in the education of archaeologists and the relatively small impact that processual archaeology made on Irish archaeologists compared to their British counterparts. There were exceptions to this situation, however, including Martin Jope in Queen’s University Belfast and Michael O’Kelly in University College Cork, who did display an interest in environmental aspects of archaeology during the 1960s and early 1970s. Monk is of the opinion that the future is now brighter than ever before for Irish environmental archaeology as a result of an increasing number of environmental archaeologists in more regular long term employment within both the commercial archaeological sector and the universities. The second part of the paper provides some suggestions as to how to move the study of plant macrofossils forward within an Irish context. He stresses the importance of attempting to synthesise the grey literature that has been produced as a result of the upsurge of developer-led archaeology in recent times. In addition, he believes that multidisciplinary research projects which draw together diverse archaeological approaches have the potential to both improve and challenge the interpretive basis of our research within an Irish context.

Ingelise Stuijts discusses the state of wood and charcoal research in Ireland and explores the value of the analysis of these ecofacts to archaeological investigation and a history of the discipline in Ireland. She provides information on methodologies, together with details of how to sample for wood and charcoal. Wood was readily available in prehistoric times and hence was used for a variety of purposes, from the building of structures to the crafting of domestic and artistic objects. Much of this wood ultimately ended up in domestic fires. Outside Ireland, the study of wood and charcoal has long been an integrated part of archaeological excavations. Such studies have provided significant insight into wood usage, woodland management and woodland changes over time. The last ten years has, however, seen a growing interest in wood and charcoal analysis in Ireland, which has resulted in some very interesting studies. Three examples of wood and charcoal research in Ireland are presented; data from Derryville Bog show how wood usage changed over time and it is suggested that the observed changes seen in wood usage over time may point to the impact of anthropogenic changes in the local landscape in the marginal areas surrounding the bog. Evidence from fulachta fiadh and West End, Dublin, are also presented. Stuijs points out that understanding wood usage should go beyond wood identification and that future research should incorporate more aspects of wood analysis, such as the examination of annual ring patterns, wood quality and insect damage. She concludes that it is only through the full integration of environmental analysis and archaeological excavation that a deeper understanding of the life and environment of prehistoric people will be realised.

Meriel McCatchie explores the importance of the non-wood plant macrofossil record within Irish environmental archaeology. She presents a methodological review of the approaches and techniques used in the retrieval, identification and interpretation of non-wood plant macro-remains from archaeological deposits. The range of information that can be gleaned from the study of plant macro-remains preserved through various mechanisms is explored and the benefits of integration with a range of other archaeological and environmental approaches are also considered. Development of the study of the discipline in Ireland is explored, but she also draws attention to the lack of well-funded, interdisciplinary projects combining archaeological excavations with a range of environmental analyses, including archaeobotanical remains, in Ireland. The work of the Discovery Programme is an exception to this, such as the ongoing research project at the waterlogged Mesolithic site at Derragh, Lough Kinale, Co. Cavan. A guide towards the selection and processing of samples is presented, and methods relating to the extraction and identification of plant macro-remains are examined. A case study from Kerlogue, Co. Wexford, is presented, demonstrating an approach in the interpretation of plant macro-remains by assessing the significance of material from prehistoric and Early Medieval deposits. McClatchie also draws attention to a number of problems for the discipline in Ireland, problems which are also prevalent in a number of other environmental archaeological disciplines, such as palaeoentomology. There are very few practising archaeobotanists specialising in Ireland, which has resulted in a situation where interpretations suggested by individual workers often fail to be critically discussed within the Irish community. Moreover, there has been a lack of integration between individual site assemblages and the archaeological evidence within overall excavation reports (like many other environmental approaches, such specialist reports may often be relegated to appendices, with little or no attempt at integration) and thus the archaeobotanical record can often be perceived as ‘dealing with interactions between plants and various ecological factors rather than interactions between people, plants and environments’. She also suggests that there is a lack of cohesion in research, combining with the small number of studies being published, resulting in a situation whereby international audiences are often not well-informed about recent and current work in Irish archaeobotany. A good example of this problem is shown in a recent publication which explores the archaeobotanical record from Europe, but where a discussion of the Irish record is lacking (Colledge and Connolly in press).

Gill Plunkett’s contribution focuses on the well-established environmental archaeological technique of pollen analysis that enables the reconstruction of past vegetation changes in the landscape. She makes the point that from an archaeological perspective, pollen records contain an important history of human interference with the natural environment and how they have the potential to provide further insights into human activity that can greatly complement and augment the archaeological record. The paper commences with a history of archaeology-related pollen studies in Ireland from the 1920s up until recent times before moving on to a methodological overview of palynological techniques. It then examines the role pollen analysis has played in archaeological research in Ireland and draws on three cases studies to illustrate the diverse contributions it can make to the study of past human activity. The first case study focuses on the contentious debate concerning the Elm Decline and the earliest farming in Ireland and clearly portrays the complexity of interpreting the pollen record, while also drawing attention to the potential of the technique to shed light on activity not apparent from the archaeological record. The second study concentrates on recent findings derived from pollen studies undertaken near Late Bronze Age hillforts. This information has revealed that, whatever role these sites had, at least a number of them were supported by a thriving, mixed farming economy that persisted for several centuries. The final case study reviews the extensive pollen evidence now available from the Late Iron Age and Early Medieval periods which has revealed that a widespread expansion in farming pre-empted the arrival of Christianity in the island, with a further intensification of agriculture having been associated with the founding of monastic enclosures and the proliferation of secular sites during the seventh century. The pollen record during this period also complements the available archaeo-environmental and literary evidence for a well-developed, mixed agricultural economy, thereby highlighting the extent of anthropogenic impact on the landscape at this time. One of the main conclusions of the paper is to highlight how considerable opportunities remain for the integration of archaeological and palynological research to enable a more holistic reconstruction of past human interactions with the landscape.

In the fourth section of the book three approaches that have been applied to environmental archaeological research within an Irish context are explored, namely alluvial geoarchaeology, palaeohydrological investigations and wetland archaeology. Tony Brown and colleagues provide a detailed summary of alluvial geoarchaeology in Ireland. There has been relatively little research in this area in Ireland, although they draw attention to the fact that the great Irish Quaternary scientist, G. F. Mitchell could perhaps be viewed as the father of Irish geoarchaeology. The topographic relief and high rainfall of Ireland, especially within the midlands area have ensured that the country is covered by a patchwork of lakes, raised mires and alluvial floodplains. These landforms provide the potential for multi-proxy and multi-scale environmental reconstruction. The linkage of lakes, bogs and alluvial areas provided important places for activity during the Mesolithic, such as those associated with the River Bann, whilst during the Neolithic and later periods alluvial environments appear to have been important foci for ritual activity and deposition. The importance of alluvial places continued into the Early Christian period, with lake and riverine islands becoming favoured ecclesiastical establishments. The relationship between archaeology and alluvial environments is thus clear and has enormous potential. This potential is explored through several detailed case studies, including raised mire and alluvial data from the Little Brosna Valley in the middle Shannon Basin, the Liffey Basin in Co. Kildare and the River Lee and the Gearagh in Co. Cork. These, along with selected other studies illustrate that the alluvial geoarchaeology of Ireland has yet to be seriously evaluated and the great potential that exists herein. The conclusion reached is that the low-energy environments of most Irish floodplains have almost certainly entombed abundant evidence of alluvial landscape change, which awaits excavation. There are, however, obvious problems concerning high water-tables, but there are also unique opportunities through the combination and linkage of alluvial, lacustrine and mire based records of environmental change and the human creation of the Irish landscape.

Chris Caseldine and Ben Gearey draw attention to palaeohydrological investigations of raised Bogs in Ireland, by highlighting work undertaken by them and their colleagues at Derryville Bog, Co. Tipperary. They discuss the value of raised (ombrotrophic) mires for the study of past climate change, via palaeohydrological sequences. Although there have been some previous palaeohydrological studies in Ireland, they point out that there has been little attempt made to link such investigations to archaeological investigations and sequences, which is one of the strengths of the Derryville study. They discuss the strengths and weaknesses of the three main palaeohydrological proxy techniques of plant macrofossil, peat humification and testate-amoebae analyses and present in detail the results from one peat sequence (DER18) from Derryville. The different proxies show similar patterns, although there are discrepancies in the timing and magnitude of palaeohydrological change, and suggest that the development of the bog appears to have been driven largely by autogenic (internal) rather than allogenic (e.g. climate) factors. The need for further, multi-proxy palaeohydrological studies in Ireland is stressed and the context this can provide for wetland archaeological sites highlighted.

Gill Plunkett and Conor McDermott highlight the importance of wetlands as significant features of the Irish landscape and how wetland and environmental archaeology are strongly interlinked. This is because wetland environments preserve many of the eco-facts which are integral to environmental archaeology, and have been central to the reconstruction of past landscapes and environments, ever since the inception of archaeology and palaeoecology in Ireland. Following a history of the discipline and its contribution, the authors focus on two case studies, to illustrate how the study of wetland environments has helped us to understand past human activity. The first example is from the Lower Bann floodplain and its associated Later Mesolithic archaeology embedded within diatomite and peat deposits, and illustrates how the dynamic floodplain and its ecosystem created a situation rich in environmental resources. The conditions which created the preservation of the environmental record, however, have also impacted the location of former occupation sites and created a partial archaeological record, impacting on their survival and identification. Thus, fluctuating water-levels associated with the River Bann contributed significantly to flooding and depositional processes, whilst also eroding, obscuring or obliterating much evidence for human occupation. Plunkett and McDermott then draw attention to the accumulating body of archaeological sites in raised bogs, namely trackways. The distribution of many of these structures reveals significant continuity in the use of particular locations through many periods, although at some sites, such as Derryville Bog, dating evidence indicates that trackway construction and bog use was often episodic, and that for some periods at least, such as the Middle to Late Bronze Age, may have taken place during periods of drier/warmer conditions. Plunkett and McDermott conclude by highlighting the opportunities provided by the study of wetlands within their wider context to address the relationships between socio-economic, cultural and environmental factors within the archaeological record.

The fifth and final section of the book comprises a paper by John Ó Néill which provides an important overview of heritage legislation and environmental archaeology for the island of Ireland. Following the partition of Ireland into Northern Ireland and Saorstát Eireann in 1921, the two separate legislative jurisdictions replaced the existing Ancient Monuments Protection (Ireland) Act of 1882 with the Ancient Monuments Act (Northern Ireland) 1926 and the National Monuments Act 1930, respectively. As such, it has been necessary for Ó Néill to provide a separate review of the development of heritage legislation for both Northern Ireland and the now Republic of Ireland. The impact of such legislation on environmental archaeology is examined, both in the context of its protection and policy against the reality of its practice, particularly with regard to excavation. The evolution of the legislation and its current status is central to understanding its influence on the practice of environmental archaeology in Ireland. Ó Néill concludes with a summary statement which makes the point that while technical and academic standards in Irish environmental archaeology can be adequately monitored through peer review and debate, the legislative protection afforded to environmental archaeological materials is explicit in the Republic of Ireland but non-specific in Northern Ireland. In both jurisdictions, the licensing system for archaeological excavations provides a safety net whereby threats to soils and other materials utilised in environmental archaeological studies can be identified and mitigated. The legal impetus to engage in the study of environmental archaeology as part of this work, however, lies solely with the conditions under which the licences for archaeological excavation are issued.

Conclusions

It is inevitable that a number of underlying themes and recurrent lines of thought will become evident in a volume such as this. Most of the authors lament the lack of publication of many specialist reports that are of relevance to environmental archaeologists. This situation has meant that it is virtually impossible to undertake synthesis studies on the different aspects of environmental archaeology which have the potential to enable the identification of broader trends in relation to chronology, status, location etc. It is clearly of major importance to archaeologists and environmental archaeologists alike that this situation is rectified on both sides of the border and that the vast amount of grey literature becomes more publicly accessible, perhaps via publication on the internet.

On a more positive note many of the contributors highlight the value of multidisciplinary projects which involve close communication between archaeologists and environmental archaeologists from the earliest stages of the research. One shining example of a highly successful project of this nature, which is referred to frequently throughout the volume, is the Lisheen Archaeological Project which involved the excavation of Derryville Bog, Co. Tipperary, by Margaret Gowan and Co. Ltd. during the late 1990s. The results of this research project have recently been published as a monograph (Gowen et al. 2005). In addition to archaeological excavation the project included pollen, peat stratigraphy, wood and insect analyses in addition to peat humification, testate amoebae and plant macrofossil studies. Plunkett and McDermott (this volume) have gone so far as to say that this study ‘marks the acme of combined wetland-environmental studies in Irish archaeology to date’. However, this project tends to be the exception rather than a rule. Too often, environmental archaeological results are relegated to report appendices and there is limited opportunity for the environmental data to be fully integrated with the archaeological results. We believe that a more holistic approach, which attempts to integrate all the various lines of evidence, can be immensely valuable and allow researchers to ask more searching questions of the archaeological record. It is therefore pleasing that the importance of the environmental archaeological record is explicitly recognised within the recently published Heritage Council document–Research Needs in Irish Archaeology (2006)–in which key research themes have been identified. The relationships between climate, environment and societal change are one of the recognised themes, an area which is highlighted by several contributors to this volume. Other important areas where environmental archaeology can make an important contribution include ‘Landscape and Settlement’ and ‘Territories, Boundaries and Cultural Identity’. If we are to address some of these themes in a holistic way, however, much greater interaction between different specialists needs to happen, with a move towards integration of the various lines of evidence.

Although much research has been undertaken on environmental archaeology within an Irish context a lot more work remains to be done. Ireland has a rich natural and archaeological landscape brimming with potential in addition to an increasing number of highly skilled environmental archaeologists. It is up to the broader archaeological community to work closely with the University, Commercial and Government sectors to ensure that we do not waste the opportunities presently available to us and that we continue to strive to develop Ireland’s position within the field of environmental archaeology.

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Note

The editors have not standardised the use of the terms Early Christian and Early Medieval throughout the volume. Both terms are taken to mean the period from approximately AD 432 to AD 1169.

1

Radiocarbon Dating: A Practical Overview

Philip Barratt and Paula J. Reimer

Abstract

Today it would be difficult to imagine archaeology without the availability of radiocarbon dating. It has revolutionised our ability to provide absolute dates for objects and places, and allows us to compare their place in time with others from around the world. All of this has been made possible simply from measuring the properties of a simple and abundant element–carbon. This paper describes some of the stages in the development of the technique, why it works and how to use it. We especially highlight its role in Ireland, home to one of the world’s leading high-precision radiocarbon laboratories. We aim to provide the user of radiocarbon dating with the necessary information to obtain optimum results and how best to convey these to a wider audience.

Introduction

Time is inherently important to us all; we relate to our past and anticipate and plan our futures using concepts of time. The physical world we inhabit changes at scales of minutes to millennia. The environmental archaeologist attempts to describe both the human and environmental record through time in a way that is sensible to the nonspecialist. To do this, places and events of the human past need to be set in a chronological context along with the environments they inhabited. This is especially important when investigating the varying impact of people on a landscape that is changing on a range of temporal scales.

Since its discovery in the 1940s, radiocarbon dating has provided archaeologists with a tool that has revolutionised our understanding of the human past (Renfrew 1973). An increasing appreciation of the contribution of environmental and earth science disciplines to archaeology has, in part, been enabled through an improvement of chronological control provided by radiocarbon dating. Continuing advances in methods and technology allow the practitioner to begin to unravel the relationships between temporally complex landscapes and human activity over the Holocene. As people move and work within this environment the challenges for the environmental archaeologist will change and the understanding required to date the human occupation and use of the land may well pass through many paradigm shifts.

History of Radiocarbon Dating in Ireland

The Belfast Radiocarbon Laboratory, based in the Palaeoecology Centre at Queen’s University Belfast, has been providing dates since 1969 and has led the development of high precision liquid scintillation counting (Pearson 1979; 1980). Since the early days, researchers have been involved in dating archaeological and environmental materials. Contributions to the understanding of key archaeological sites in Ireland such as the Neolithic passage tombs at Newgrange and Knowth, Co. Meath, and Iron Age Navan Fort, Co. Armagh, have been taking place since the 1970s. The laboratory has also been involved with the dating of important sites in England such as the world renowned Stonehenge in Wiltshire (Cleal et al. 1995), and the so-called ‘Seahenge’ timber circle in East Anglia (Bayliss et al. 1999). The laboratory has worked closely with researchers from the Palaeoecology Centre at Queen’s, building a wealth of experience in archaeological and palaeoenvironmental applications. Perhaps one of the most important contributions to the latter is that of tephrochronology; the use of volcanic ash deposited after an eruption to date and correlate sedimentary horizons (see Pilcher, this volume). Assuming the tephra found in a deposit can be uniquely identified, a radiocarbon date on the sediments or plant macrofossils at the tephra horizon can be effectively transferred to other sites at the point where the same tephra has been identified. This is of course a simplified description of tephrochronology which has become an important part of the chronologist’s toolkit and the following references provide further explanation and uses of the technique–Pilcher et al. (1995), Haflidason et al. (2000), Plunkett et al. (2004) and Hall and Mauquoy (2005).

The Belfast Radiocarbon Laboratory, in conjunction with the Dendrochronology Laboratory in the Palaeoecology Centre, Queen’s University Belfast, began one of the earliest European radiocarbon calibration research programmes (Pearson et al. 1977) and it has been a key centre for the development of internationally accepted radiocarbon calibration curves. The