THAMES WATER MAINS REPLACEMENT BOURTON-ON-THE-WATER GLOUCESTERSHIRE ARCHAEOLOGICAL WATCHING BRIEF For OPTIMISE on behalf of THAMES WATER UTILITIES CA PROJECT: 3198 CA REPORT: 10173 OCTOBER 2010 THAMES WATER MAINS REPLACEMENT BOURTON-ON-THE-WATER GLOUCESTERSHIRE ARCHAEOLOGICAL WATCHING BRIEF CA PROJECT: 3198 CA REPORT: 10173 prepared by Jonathan Hart, Publications Officer and Jamie Wright, Project Officer date 24 October 2010 checked by Cliff Bateman, Project Manager date 25 0ctober 2010 approved by Simon Cox, Head of Fieldwork signed date 26 October 2010 issue 01 This report is confidential to the client. Cotswold Archaeology accepts no responsibility or liability to any third party to whom this report, or any part of it, is made known. Any such party relies upon this report entirely at their own risk. No part of this report may be reproduced by any means without permission. © Cotswold Archaeology Building 11, Kemble Enterprise Park, Kemble, Cirencester, Gloucestershire, GL7 6BQ Tel. 01285 771022 Fax. 01285 771033 E-mail: [email protected] © Cotswold Archaeology Thames Water Mains Replacement, Bourton-on-the-Water, Gloucestershire: Archaeological Watching Brief CONTENTS SUMMARY........................................................................................................................ 2 1. INTRODUCTION ................................................................................................. 3 2. RESULTS (FIGS 2–5).......................................................................................... 4 3. DISCUSSION....................................................................................................... 5 4. CA PROJECT TEAM ........................................................................................... 6 5. REFERENCES .................................................................................................... 6 APPENDIX A: CONTEXT DESCRIPTIONS ..................................................................... 7 APPENDIX B: THE FINDS ............................................................................................... 8 APPENDIX C: OASIS REPORT FORM............................................................................ 8 LIST OF ILLUSTRATIONS Fig. 1 Site location plan (1:25,000) Fig. 2 The site, showing location of groundworks (1:1250) Fig. 3 Photograph, north facing section of pipe trench Fig. 4 Photograph, trenching towards probable palaeochannel 016 Fig. 5 Photograph, bank 012: looking south 1 © Cotswold Archaeology Thames Water Mains Replacement, Bourton-on-the-Water, Gloucestershire: Archaeological Watching Brief SUMMARY Project Name: Thames Water Mains Replacement Location: Bourton-on-the-Water, Gloucestershire NGR: SP 1761 2164 to SP 1802 2153 Type: Watching Brief Date: 9 August to 13 September 2010 Location of Archive: To be deposited with Corinium Museum Site Code: TBW 10 An archaeological watching brief was undertaken by Cotswold Archaeology during groundworks along the Thames Water Mains Replacement, Bourton-on-the-Water, Gloucestershire. Two probable Holocene palaeochannels were identified cutting into the gravel terrace of the River Windrush. Deposits of Holocene alluvium were also present and were sealed by a low gravel bank which was visible as an earthwork either side of the pipeline. Although it remained undated, the bank was clearly cut by the existing field boundaries. 2 © Cotswold Archaeology Thames Water Mains Replacement, Bourton-on-the-Water, Gloucestershire: Archaeological Watching Brief 1. INTRODUCTION 1.1 In August and September 2010 Cotswold Archaeology (CA) carried out an archaeological watching brief for Optimise, on behalf of Thames Water Utilities, along the Thames Water Mains Replacement, Salmonsbury Fields, Bourton-on-the- Water, Gloucestershire (NGR: SP 1761 2164 to SP 1802 2153; Fig. 1). The work comprised Permitted Development but was governed by Thames Water’s responsibilities under the Code of Practice on Conservation, Access and Recreation (LHA 2010). The objective of the watching brief was to record all archaeological remains exposed during the development. 1.2 The watching brief was carried out in accordance with a request for archaeological recording by Charles Parry, Senior Archaeological Officer, Gloucestershire County Council (GCC), and with a Brief for archaeological recording issued by Lang Hall Archaeology (LHA) for Optimise, on behalf of Thames Water Utilities (LHA 2010). The methodology of the work was detailed in a subsequent Written Scheme of Investigation (WSI) produced by CA (2010) and approved by Optimise acting on the advice of LHA. The fieldwork also followed the Standard and Guidance for an Archaeological Watching Brief issued by the Institute for Archaeologists (2008), the Statement of Standards and Practices Appropriate for Archaeological Fieldwork in Gloucestershire issued by Gloucestershire County Council Archaeology Section (1995), the Management of Archaeological Projects (English Heritage 1991) and the Management of Research Projects in the Historic Environment (MORPHE) (English Heritage 2006). The site 1.3 The pipeline route measures c. 400m in length and traverses meadows to the east of Bourton-on-the-Water within the floodplain of the Rivers Dikler and Eye, both tributaries of the River Windrush (Figs 1 and 2). It lies at approximately 120m AOD and is generally level ground. The majority of the site forms part of the Salmonsbury Meadows, a Site of Special Scientific Interest designated because of its species-rich unimproved meadows (GWT 2010). 1.4 The underlying solid geology of the area is mapped as Mudstone of the Jurassic Charmouth Mudstone Formation (BGS 2010). Quaternary deposits of the Sherborne Member (limestone gravel forming a terrace of the River Windrush) are mapped to 3 © Cotswold Archaeology Thames Water Mains Replacement, Bourton-on-the-Water, Gloucestershire: Archaeological Watching Brief the east of the River Dikler and west of the River Eye, while Holocene Alluvium deposits (Clay, Silt, Sand and Gravel) are mapped between the rivers. Blue-grey clay overlain by calcareous gravel was exposed during the watching brief. Archaeological background 1.5 The Scheduled Monument of Salmonsbury Camp, an Iron Age hillfort with Neolithic origins, is located 800m to the south-west of the site (Lang 2008). A geophysical survey of the pipeline route undertaken by Archaeological Surveys Ltd indicated the presence of features of unknown provenance, although the existing pipe had caused considerable magnetic disturbance to the geophysical plot (AS 2010). Methodology 1.6 The fieldwork followed the methodology set out within the WSI (CA 2010). An archaeologist was present during intrusive groundworks comprising deturfing throughout the 13m wide fenced corridor and the subsequent excavation of a 0.6m– 1m wide pipe trench as well as launch and reception pits for boring under the River Eye (Fig. 2). 1.7 Where archaeological deposits were encountered written, graphic and photographic records were compiled in accordance with CA Technical Manual 1: Fieldwork Recording Manual (2007). 1.8 The archive from the watching brief is currently held by CA at their offices in Kemble and will be deposited with Corinium Museum, Cirencester. A summary of information from this project, set out within Appendix C, will be entered onto the OASIS online database of archaeological projects in Britain. 2. RESULTS (FIGS 2–5) 2.1 The earliest encountered deposit was the geological substrate, comprising compact blue-grey clay 020/206, exposed at the bases of the pipe trench and the launch pit (Fig. 3).. It was overlain by several layers of white calcareous gravel with occasional bands of pale grey clay (layers 003, 017–019, 204 and 205), together measuring up to 0.4m thickness. The uppermost of these deposits had been cut by undated tree- throw pit 004 and by two probable palaeochannels, each approximately 50m–65m wide. Unfortunately, the extremely wet ground conditions prevented these deposits 4 © Cotswold Archaeology Thames Water Mains Replacement, Bourton-on-the-Water, Gloucestershire: Archaeological Watching Brief from being recorded in section, so the morphology and depths of the probable paleochannels remained undetermined (Fig. 4). Neither the tree-throw pit nor the possible palaeochannels were recorded during the preceding geophysical survey. 2.2 The tree-throw pit and probable palaeochannels were sealed by several alluvial clay deposits (006, 009, 014, 015 and 203), which together were up to 0.4m thick. Of these, layer 009 contained a 0.05m thick deposit of tree bark fragments, 011. 2.3 Gravel bank 012 was built onto alluvial clay layer 009 (Fig. 5). This bank was 1.3m wide and 0.17m high and was visible as an earthwork within the fields either side of the pipeline, where it was clearly cut by the existing field boundaries. The bank was not recorded during the geophysical survey. 2.4 The foregoing deposits were sealed by subsoil 010/202 which was itself covered by topsoil (001, 002, 013 and 201). A layer of fragmented tree bark, 008, was present within the topsoil. The latest encountered deposits were the cut and fills of the existing water mains (cuts 207, 209 and 211; fills 208, 210 and 212). The finds 2.5 The recovered finds assemblage comprises unstratified material collected during de- turfing. This material includes Roman pottery, comprising single sherds of Central Gaulish Samian ware, Central Gaulish black-slipped ware, and a sandy greyware. The remaining material is modern and includes