A Report for English Heritage Rapid Coastal Zone Assessment for The Isles of Scilly Charles Johns Richard Larn Bryn Perry Tapper May 2004 Report No: 2004R030 HISTORIC ENVIRONMENT SERVICE Environment and Heritage, Planning Transportation and Estates, Cornwall County Council Kennall Building, Old County Hall, Station Road, Truro, Cornwall, TR1 3AY tel (01872) 323603 fax (01872) 323811 E-mail [email protected] 1 www.cornwall.gov.uk Acknowledgements This study was commissioned by English Heritage. Ian Morrison, Inspector of Ancient Monuments and Fachtna McAvoy, the Project Officer, provided guidance and support throughout, advice and help was also given by Vanessa Straker, South-West Regional Scientific Officer, Ian Oxley, Head of Maritime Archaeology, Annabel Lawrence, Archaeologist (Maritime) and Dave Hooley of the Characterisation Team. Help with the historical research was provided by various individuals and organisations, in particular: Amanda Martin and Sarnia Butcher of the Isles of Scilly Museum; Sophia Exelby, Receiver of Wreck; Sandra Gibson of Gibsons of Scilly; Adrian Webb, Research Manager, Hydrographic Data Centre, UKHO, Taunton; Ron Openshaw of the Bartlett Library, National Maritime Museum, Falmouth; Cornwall County Council’s Library Service and the Helston branch library. David Graty at the National Monument Record and June Dillon at the United Kingdom Hydrographic Office provided advice and help obtaining shipwreck information. Underwater images east of the Bristows, St Martin’s were collected by Dave Parry during a Plymouth Marine Laboratory research expedition in March 2003, funded by DEFRA through projects AE1137 and CDEP 84/5/295 for rapid assessment of marine biodiversity (RAMBLERS) External consultants for the project were: Richard Larn who provided maritime advice and expertise and Gill Arbery, Isles of Scilly Conservation Officer and English Heritage Field Monument warden who facilitated the consultation exercise and advised on conservation issues. Within the Historic Environment Service, Charles Johns was the Project Manager and also undertook the research and consultation exercises and compiled the report; Bryn Perry Tapper undertook and supervised the GIS and database method and compiled the characterisation texts; Andy Young and Emma Taylor carried out the NMP plot; Ainsley Cocks undertook database entry and advised on significance; Peter Herring advised on characterisation; Cathy Parkers advised on significance, Megan Val Baker contributed to the characterisation section of the report, mapped the HLC types and undertook database entry, Peter Rose edited the text and provided administrative support. The report owes much to the extensive work previously carried out in Scilly by Jeanette Ratcliffe. The views and recommendations expressed in this report are those of the Historic Environment Service projects team and are presented in good faith on the basis of professional judgement and on information currently available. Maps The terrestrial maps in this publication are based on Ordnance Survey material with the permission of the Ordnance Survey on behalf of the Controller of Her Majesty's Stationery Office ©Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution and/or civil proceedings. The map data, derived from Ordnance Survey mapping, included within this publication is provided by Cornwall County Council under licence from the Ordnance Survey in order to fulfil its public function to publicise local public services. Persons viewing this mapping should contact Ordnance Survey copyright for advice where they wish to licence Ordnance Survey mapping for their own use. Cornwall County Council Licence No. 100019590. Maritime maps in this publication are based on United Kingdom Hydrographic Office (UKHO) Admiralty Charts 34, 1148, 2565, 1178 and 265 with the permission of the UKHO. Cornwall County Council Data Licence 052003.011. All Rights Reserved. Cover illustration Aerial view of Bryher with New Grimsby Channel separating it from Tresco and St Martin’s in the far distance (photo: ©Gibson Collection) © Cornwall County Council 2004 No part of this document may be reproduced, stored in a retrieval system, or transmitted in any form or by any means without the prior permission of the publisher. 2 Contents 1 Summary 14 1.1 Current issues 15 1.2 Summary of recommendations 15 1.2.1 Transport Strategy 15 1.2.2 The historic maritime resource 16 1.2.3 Coastal erosion and monitoring 16 1.2.4 Research themes 17 1.2.5 Conservation Plan for The Garrison 17 1.2.6 Data sharing 17 1.3 Provisional timetable for implementation 18 2 Introduction 20 2.1 Project background 20 2.2 The Isles of Scilly 21 2.3 Previous work 21 2.4 Organisation of this report 22 3 Aims and objectives 24 3.1 Aims 24 3.2 Objectives 24 4 Methodology 25 4.1 Survey method 25 4.2 The project area 25 4.3 Research, data collection and collation 26 4.4 Consultation 27 4.5 Database records and GIS mapping 27 4.5.1 Method 27 4.5.2 CCC HER, NMR, CICC HER, RSM, CIOSS 27 4.5.3 UKHO 28 4.5.4 Submergence models 29 4.5.5 Archaeological Item Record 30 4.6 Integration with the National Mapping Programme 30 4.7 Approaches to characterisation 30 5 Geology and nature of the seabed in the project area 31 5.1 Geology and geomorphology 31 5.2 Tides and tidal streams 32 5.3 Wave climate 33 5.4 Sediment mobility 33 5.5 Major seabed types within the archipelago 34 6 Existing statutory and non-statutory controls 39 6.1 Sites of Special Scientific Interest 39 3 6.2 Marine Park and cSAC 39 6.3 Candidate SAC, SPA and Ramsar designations 39 6.4 AONB / Heritage Coast 39 6.5 Scheduled Monuments 41 6.6 Listed buildings 41 6.7 Wreck Law 41 6.7.1 Merchant Shipping Act 1995 42 6.7.2 The Protection of Wrecks Act 1973 and the National Heritage Act 2002 42 6.7.3 The National Heritage Act 2002 43 6.7.4 Protection of Military Remains Act 1986 44 6.8 Portable Antiquities Scheme 44 6.9 The Historic Environment Record for Cornwall and the Isles of Scilly 44 6.10 Planning instruments 44 6.11 Conservation Area 45 6.12 Local plans 45 6.13 Local bylaws 46 6.14 Proposed shipping exclusion zone 46 7 Threats to the historic resource 47 7.1 Transport related development 47 7.1.1 St Mary’s harbour 47 7.1.2 Recommendations for St Mary’s harbour 49 7.1.3 The off-island quays 49 7.1.4 General recommendations for the off-island quays 51 7.2 Rising sea level, climate change and coastal erosion 52 7.2.1 Current coastal protection and mitigation 54 7.2.2 Coastal defence strategy for Scilly 54 7.2.3 Predicted future trends 55 7.2.4 Recommendations 56 7.3 Unsystematic sampling and collection of finds 57 7.3.1 Recommendations 57 7.4 Sea action 57 7.4.1 Recommendations 57 7.5 Dredging, sand and gravel extraction 58 7.6 Visitor pressure 58 7.6.1 Recommendations 59 7.7 Irresponsible diving (treasure hunting) 59 7.7.1 Threats 59 7.7.2 Existing local safeguards 60 7.7.3 Recommendations 60 7.8 Marine wood borers, bacterial and fungal activity 61 7.9 Commercial fishing activity (scalloping) 62 7.10 Submarine cable laying 63 7.10.1 Recommendations 63 7.11 Fly tipping 63 4 7.11.1 Recommendations 63 7.12 Minor threats 63 7.12.1 Bait digging 63 7.12.2 Recommendations 64 7.12.3 Metal detectors 64 7.12.4 Recommendations 64 7.12.5 Anchors, moorings and outhauls 64 7.12.6 Recommendations 64 8 Assessment by period 65 8.1 Prehistory 65 8.1.1 The Palaeolithic (to c7000 BC) 65 8.1.2 The Mesolithic (c7000 – 4000 BC) 65 8.1.3 The Neolithic (c4000 – 2500 BC) 67 8.1.4 The Bronze Age (c2,500 – 700 BC) 67 8.1.5 The Iron Age (c700 BC – AD 43) and Romano-British period (AD 43 – AD 410) 71 8.2 Medieval 73 8.2.1 Early medieval (AD 410-1066) 73 8.2.2 Later medieval (1066-1540) 75 8.3 Post-medieval to modern 79 8.3.1 Post-medieval (c1540 – c1740) 79 8.3.2 Early modern or industrial age (c1740-1914) 81 8.3.3 Modern (1914 onwards) 83 9 Assessment by theme 86 9.1 Palaeoenvironments and the creation of the coastal landscape 86 9.1.1 Coastal palaeoenvironmental studies in Scilly 86 9.1.2 Old Town Bay Coast Protection Scheme 90 9.1.3 Submergence studies 90 9.1.4 Professor Charles Thomas’ model for sea level change, 1985 90 9.1.5 Assessment of the intertidal ‘peats’, 1989-1993 91 9.2 Dendrochronology 93 9.3 Historic management of the coastal landscape 93 9.4 Coastal settlement 94 9.4.1 Prehistoric period 95 9.4.2 The medieval period 97 9.5 Religious, ritual and funerary 97 9.5.1 Neolithic/Bronze Age 99 9.5.2 Iron Age and Romano-British periods 99 9.5.3 Early medieval period 101 9.6 Coastal and maritime trade, transport and communications 102 9.6.1 Prehistoric and Romano-British maritime trade 102 9.6.2 Medieval maritime trade 103 9.6.3 Post-medieval period 103 9.7 Coastal industry 105 9.7.1 The kelp burning industry in Scilly 105 9.7.2 Shipbuilding in Scilly 106 9.7.3 Limeburning 108 9.7.4 Smuggling and the coastguard 108 9.8 Coastal fortifications and maritime conflict 110 9.8.1 Prehistoric/Romano-British (to AD 410) 110 9.8.2 Medieval (c410-1540) 110 9.8.3 Post-medieval (c1540-1740) 110 5 9.8.4 Early modern (1740-1914) 111 9.8.5 Modern (1914 onwards) 113 9.9 Exploitation of marine resources 113 9.9.1 Prehistory and the Roman period 113 9.9.2 The historic period 115 9.10 Harbour and quay installations 117 9.11 Shipwreck 119 9.11.1 Introduction 119 9.11.2 Main located historic shipwreck sites in Scilly ordered by date 121 9.11.3 Unlocated known historic wreck sites, ordered by date 126 9.11.4 Finds that may relate to historic wrecks 127 9.11.5 Protected war graves, deep water shipwrecks and World