Great Yarmouth Third River Crossing Appendix 9C: Borehole Log Review and Deposit Modelling Report Document Reference: 6.2 Great Yarmouth Third River Crossing Application for Development Consent Order Document 6.2: Environmental Statement Volume II: Technical Appendix 9C: Borehole Log Review and Deposit Modelling Report Planning Act 2008 The Infrastructure Planning (Applications: Prescribed Forms and Procedure) Regulations 2009 (as amended) (“APFP”) APFP regulation Number: 5(2)(a) Planning Inspectorate Reference Number: TR010043 Author: Norfolk County Council Document Reference: 6.2 – Technical Appendix 9C Version Number: 0 – Revision for Submission Date: 30 April 2019 Great Yarmouth Third River Crossing Borehole log review and deposit modelling report Ref: 204901.01 September 2018 wessexarchaeology © Wessex Archaeology Ltd 2018, all rights reserved. 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Document Information Document title Third River Crossing, Great Yarmouth Document subtitle Geoarchaeological borehole review and deposit modelling Document reference 204901.01 Client name WSP UK Ltd Address 3 White Rose Office Park Millshaw Park Lane Leeds LS11 0DL Site location Great Yarmouth County Norfolk National grid reference 652500 305920 (TG 52500 05920) Statutory designations Planning authority Norfolk County Council WA project name Great Yarmoth Third River Crossing WA project code 204901 (204900) Project management by Dave Norcott Document compiled by Claire Mellett Contributions from Holly Rodgers, Andrew Shaw Graphics by Nancy Dixon Quality Assurance Version & issue date Status Author Approved by V1 07/09/2018 External draft CLM DRN Third River Crossing, Great Yarmouth Geoarchaeological borehole review and deposit modelling Contents Summary .........................................................................................................................................ii Acknowledgements .......................................................................................................................... i 1 INTRODUCTION ................................................................................................................... 1 1.1 Project background ....................................................................................................... 1 1.2 Site location and geology .............................................................................................. 1 1.3 Summary of previous geoarchaeological work .............................................................. 3 1.4 Scope of document ....................................................................................................... 3 2 GEOARCHAEOLOGICAL BACKGROUND .......................................................................... 4 2.1 Lower Palaeolithic (800 – 243 ka) ................................................................................. 4 2.2 Middle Palaeolithic (243 – 36 ka) .................................................................................. 5 2.3 Early Upper Palaeolithic (36 – 13 ka) ............................................................................ 6 2.4 Late Upper Palaeolithic to Medieval (13,000 BC – AD 1500) ........................................ 6 3 AIMS AND OBJECTIVES ...................................................................................................... 7 4 METHODOLOGY .................................................................................................................. 7 4.1 Geotechnical data ......................................................................................................... 7 4.2 Review of geotechnical data ......................................................................................... 8 4.3 Deposit modelling ......................................................................................................... 8 5 RESULTS .............................................................................................................................. 9 5.1 Review of geotechnical logs ......................................................................................... 9 5.2 Deposit modelling ....................................................................................................... 10 6 DISCUSSION ...................................................................................................................... 11 6.1 Geoarchaeological potential........................................................................................ 11 6.2 Potential impact .......................................................................................................... 13 7 RECOMMENDATIONS ....................................................................................................... 13 REFERENCES ............................................................................................................................. 15 Bibliography ......................................................................................................................... 15 Websites .............................................................................................................................. 16 Appendix 1 ........................................................................................................................... 17 List of Figures Figure 1 Site location plan showing transect Figure 2 Sub-surface transect across the site List of Tables Table 1 Stages of geoarchaeological assessment and recording Table 2 Stratigraphy of deposits with the proposed scheme i Doc ref 204901.01 Issue 1, Sept 2018 Third River Crossing, Great Yarmouth Geoarchaeological borehole review and deposit modelling Summary Wessex Archaeology was commissioned by WSP Ltd. to undertake a geoarchaeological assessment of geotechnical borehole data collected as part of ground investigation works in support of the proposed Third River Crossing, Great Yarmouth. The proposed scheme will provide a new bridge and associated transport links across the River Yare, which bisects the town. Construction activities include the installation of pile foundations to support the bridge structure, and ground works and landscaping associated with the new strategic road network. Previous archaeological investigations identified deposits of potential geoarchaeological significance within the proposed scheme boundary (WSP 2018; Wessex Archaeology 2018). These comprise peat and alluvium of the Breydon Formation, deposited in semi-terrestrial wetland environmental under the influence of post-glacial rising sea levels. To assess the distribution, depth and significance of the geoarchaeological resource, and therefore the possible impact of construction activities, a geoarchaeological review of 48 geotechnical borehole logs has been undertaken and the results used to construct a deposit model for the scheme area. Based on the borehole review, the stratigraphy of the site is characterised by London Clay overlain by Crag Group deposits, both of which pre-date human occupation and thus have no geoarchaeological potential. Sands and gravels of the Happisburgh Glacigenic Formation overlie Crag Group deposits, but as these were deposited during the Anglian glacial period, they have low geoarchaeological potential. The most geoarchaeologically significant deposits within the proposed scheme belong to the Breydon Formation. These deposits comprise peat and alluvium and were mapped on the western side of the River Yare. Peat deposits have high geoarchaeological potential as they may preserve palaeoenvironmental as well as archaeological material. These deposits are located at depths between -4 m OD and -10.35 m OD. Alluvial deposits overlie the peat and can be found at depths between -0.23 m OD and -10 m OD. These deposits have a lower organic content but the potential to preserve inorganic microfossils and are judged to be of medium geoarchaeological potential. On the eastern side of the River Yare, North Denes Formation is present where Breydon Formation is absent. North Denes Formation comprises sand and gravel that was deposited as part of a coastal spit/ barrier that developed from AD 500 onwards. The geoarchaeological potential of these deposits is low, although it is possible that they may contain