An Investigation of mid to late Holocene fossil insects from raised bogs in the Irish Midlands by Katie Georgina Denton Thesis submitted for the degree of Doctor of Philosophy at the University of London Institution of study: Department of Geography, Royal Holloway, University of London February 2012 1 Declaration This thesis presents the results of original research undertaken by the author and none of the results, illustrations or text are based on the published or unpublished work of others, except where specified and acknowledged. Signature: Date: 2 Abstract This dissertation presents the results of late Holocene insect fossil analysis from six raised bogs in the Irish Midlands. A distribution and taphonomic study was performed on a sequence of samples across a 1-km transect from the lagg (margin) to the dome (centre) of Ballykean Bog, County Offaly, Ireland. The purpose of this study was to detect any patterns in the taphonomy of the insect fossil assemblages, through the development of the bog and across ancient bog surfaces. This study also investigated how vegetation changes and taphonomy influence beetle assemblages from different locations across the bog surface and to test whether fossil assemblages reflect these changes. The insect faunal assemblages from the transect did not show any clear spatial or temporal patterns in fossil abundance or taxonomic diversity. However, the study demonstrated the benefit of the analysis of multiple sampling points in a bog. Multiple sampling site analysis appears to be critical in the development of a comprehensive reconstruction of key intervals of peat deposition and in providing a greater understanding of the local bog surface habitats. Insect fossil records were analysed across six raised bogs as part of a multi-proxy environmental archaeology project focusing on seven trackways, a wooden platform and a habitation structure. The archaeology dates from the early Bronze Age (1569±9 BC) at Kinnegad Bog to the Christian period (AD 900 to 1160) at Lullymore Bog. This study demonstrates that insect records associated with the minor structures, such as trackways and platforms, contained less diverse assemblages comprising of mainly generalist taxa. In comparison, the major habitation structure at Ballykean Bog had a strong anthropogenic signal. While the reasons behind the construction of the trackways and platforms remains unsolved on the basis of the multi-proxy environmental analysis, it was possible to suggest reasons for their construction based on structure directionality and historical context. 3 Acknowledgments I would like to thank the following people for their generous help and support throughout my PhD: Prof. Robert Angus (RHUL) for beetle identification assistance Miss Karen Black (ADS Ltd.) for fieldwork assistance and information transfer post- fieldwork Mr Mark Hardiman (RHUL) for useful analytical discussions Miss Jenny Kynaston (RHUL) for poster assistance and graphical advice Dr Ian Matthews (RHUL) for advice and discussions on statistical analysis, Oxcal, and for fieldwork assistance Dr Adrian Palmer (RHUL) for laboratory assistance Dr. David Smith (University of Birmingham) for allowing access to the Gorham and Girling Beetle collection and for identification assistance Mr. John Turrell (ADS Ltd.) for fieldwork assistance Miss Elaine Turton (RHUL) for laboratory assistance Ms Jane Whitaker (ADS Ltd.) for fieldwork assistance Dr. Nicola Whitehouse (QUB) for identification assistance Mr Kevin Williams (University of Reading) for fieldwork assistance I owe a particular debt of gratitude to Professor Scott Elias and Dr Nicholas Branch who supervised this project. Their guidance and enthusiasm through the development and execution of this project was invaluable, allowing me to explore new areas of scientific enquiry I didn’t know existed. Scott, I am forever grateful to you for your patience and enthusiasm. You have developed my skills and interest in palaeoentomology, skills which I hope to continue using 4 throughout my career. I am also grateful for the many discussions over the last three years; I couldn’t have done it without you! This thesis was funded by Quaternary Scientific (University of Reading) and Archaeological Development Services Ltd. I would like to thank Quaternary Scientific for this research opportunity and for recognising the potential of this study. I would like to thank my family for their continued support and tolerance throughout my PhD. I know I have disappeared for months at a time during this project but you’ll be seeing lots more of me now! Finally, I would like to thank two people who have been integral to this PhD. My best friend Robyn who has held me together and supported me throughout the duration of my PhD. Dan , you have pushed me to be the best I can be and have always been there when I have needed support. I could not have achieved this without you. 5 Contents Abstract ......................................................................................................................... 3 Acknowledgements ...................................................................................................... 4 List of Figures ................................................................................................................. 11 List of Tables .................................................................................................................. 16 1. Introduction ................................................................................................................. 19 1.1. Peatlands ...................................................................................................... 19 1.2. Factors Affecting Bog Growth, Decay and Accumulation.............................. 20 1.2.1. Environmental Gradients …………………………………………... 21 1.2.2. Wet Shifts ……………………………………………………………. 24 1.3. Palaeoenvironmental Records in Peatlands ................................................. 24 1.4. Palaeoentomological Studies of Northern European Peatlands ………... 27 1.5. Human, Environment and Climate Interactions ……………………………. 30 1.6. Societal Response to a Changing Climate ………………………………..... 32 1.7. General Aims and Objectives ………………………………………………… 35 2. Literature Review ........................................................................................................ 38 3. Methodology ................................................................................................................ 43 3.1. Fieldwork Methods ........................................................................................ 43 3.1.1. Transect Bulk Samples ................................................................ 43 3.1.2. Archaeological Bulk Samples ...................................................... 44 3.1.3. Control Bulk Samples to Archaeological Samples ...................... 45 3.1.4. Column Samples ......................................................................... 46 3.1.5. Russian Core Samples ................................................................. 46 3.1.6. Survey of Bulk Samples ............................................................... 47 3.2. Laboratory Methods ..................................................................................... 48 3.2.1. Lithostratigraphic Methods ........................................................... 48 3.2.2. Insect Extraction and Identification Methods ................................ 50 3.2.2.1. Insect Extraction ........................................................................ 50 3.2.2.2. Picking ....................................................................................... 53 3.2.2.3. Identification .............................................................................. 55 3.3. Insect Analysis Methods ............................................................................... 59 3.3.1. BugsCEP ...................................................................................... 59 3.3.2. BUGS MCR .................................................................................. 63 6 4. Distributional and Taphonomic Transect Survey .................................................... 65 4.1. Study Area ................................................................................................... 65 4.2. Lithostratigraphy and Chronology ................................................................ 66 4.3. Insect Fossil Assemblages ........................................................................... 68 4.3.1. TS0 Insect Assemblages – Lagg Area ......................................... 73 4.3.2. TS1 Insect Assemblages – 100m from Lagg Area ...................... 77 4.3.3. TS2 Insect Assemblages – 200m from Lagg Area ...................... 81 4.3.4. TS3 Insect Assemblages – 300m from Lagg Area ...................... 85 4.3.5. TS4 Insect Assemblages – 400m from Lagg Area ...................... 89 4.3.6. TS5 Insect Assemblages – 500m from Lagg Area ...................... 93 4.3.7. TS6 Insect Assemblages – 600m from Lagg Area ...................... 98 4.3.8. TS7 Insect Assemblages – 700m from Lagg Area ...................... 101 4.3.9. TS8 Insect Assemblages – 800m from Lagg Area ...................... 104 4.3.10. TS9 Insect Assemblages – 900m from Lagg Area .................... 107 4.3.11. TS10 Insect Assemblages – 1km from Lagg Area .................... 110 4.4. Insect Interpretation ..................................................................................... 114 4.5. MCR ............................................................................................................