THE IMPACT OF HISTORICAL METAL MINING ON THE RIVER SWALE CATCHMENT, NORTH , U.K.

IAN DENNIS

UNIVERSITY OF WALES, ABERYSTWYTH JULY 2005 Abstract

ABSTRACT

This investigation examines the impact of historical metal mining on the River Swale catchment, , U.K. Approximately 550,000 tonnes of Pb were extracted from mines in the Swale catchment during the eighteenth and nineteenth centuries. Mining and processing operations were relatively inefficient, leading to the discharge of large quantities of metal-rich sediment into the fluvial system. The primary aim of this thesis is to assess the physical and chemical impacts of the discharge of metals from historical mining activities on the River Swale catchment as a whole. The dispersal, storage and transfer of metal-rich sediment in formerly mined tributaries, floodplain and flood sediments are evaluated, and the environmental consequences of mining are assessed.

A detailed geochemical survey of the River Swale catchment indicates that channel and floodplain sediments within formerly mined tributaries exhibit extremely high concentrations of Pb, Zn and Cd. Similar enrichment is observed in floodplain sediments from throughout the catchment, suggesting that large volumes of material have been transported from the tributaries and deposited on the Swale floodplain. Evidence from contemporary flood sediments suggests that considerable quantities of metal-rich sediment continue to be cycled through the system almost 100 years after the cessation of mining operations. Sediment budgeting suggests that 32,000 tonnes of Pb remain stored in formerly mined tributaries, with a further 123,000 tonnes stored in the Swale floodplain. Combined storage represents more than half of the total Pb that is likely to have been released during mining operations, suggesting that the impacts of metal mining are extremely long-lasting. Concentrations of Pb, Zn and Cd in tributary, floodplain and flood sediments greatly exceed current U.K. environmental quality guidelines and catchment- specific background values. Metal enrichment as a result of historical mining operations could therefore pose a serious and long-term threat to plant and animal health in the Swale catchment.

i Acknowledgements

ACKNOWLEDGEMENTS

First, I would like to thank my supervisors, Dr. Tom Coulthard, Professor Mark Macklin, and Dr. Paul Brewer, for their advice and help with all aspects of this thesis. Grateful thanks are also extended to Dr. Bill Perkins, Dr. Nick Pearce, Lorraine Hill, Lorraine Morrison and Wynne Ebenezer, without whose invaluable guidance geochemical analyses would have proved impossible! Ian Gulley and Anthony Smith are also thanked for their assistance in producing several of the figures included in this thesis. Dr. John Ridgway is thanked for the provision of BGS G-Base data for the Swale catchment, and Dr. Sean Longfield and Victoria Townend of the Environment Agency are thanked for providing flow data from the Catterick Bridge gauging station. Thanks are also extended to the landowners of the River Swale catchment, without whose co-operation this investigation would have been impossible. Eric Johnstone, Phillippa Noble, Anna Jones, Graham Bird, Simon Gittins, Jonathan Turner and Liz Young are all thanked for their helpful discussions and much appreciated assistance with field work, and Marco van de Wiel is thanked for his advice with all things mathematical and computational.

I would also like to thank all my friends here in Aberystwyth for their assistance with ‘rest and recuperation’, especially Eric, Simon, Zenobia, Natalie, and Graham. Finally, deepest thanks are extended to my parents, Nicola, and of course Clare, who have helped me through my studies with their support and encouragement.

Ordnance Survey Landline data appears in Figures 4.6, 5.3 – 5.14 and 7.2. © Crown Copyright Ordnance Survey. An EDINA Digimap/ JISC supplied service.

ii Contents

CONTENTS

ABSTRACT i ACKNOWLEDGEMENTS ii TABLE OF CONTENTS iii LIST OF FIGURES x LIST OF TABLES xiv LIST OF PLATES xvi

CHAPTER 1 INTRODUCTION: METALS IN FLUVIAL SEDIMENTS 1.1. Introduction 1 1.2. Metals in fluvial sediments: a review 3 1.2.1. Introduction 3 1.2.2. The behaviour of metals in fluvial sediments 3 1.2.3. Metal transport in fluvial sediments 6 1.2.4. Metal storage in fluvial sediments 9 1.2.5. Remobilisation of metals 11 1.2.6. The geomorphological impacts of metal mining 12 1.2.7. Summary: Metals in fluvial sediments 15 1.3. Thesis background and aims 15

CHAPTER 2 STUDY AREA: THE RIVER SWALE CATCHMENT AND ITS MINING HISTORY 2.1. The River Swale catchment 18 2.1.1. General characteristics 18

iii Contents

2.1.2. Catchment geology 20 2.1.3. Mineralisation 22 2.1.4. Catchment geochemistry 24 2.1.5. Glacial history and Holocene development 25 2.1.6. Fluvial geomorphology 25 2.2. Metal mining in the Swale catchment 31 2.2.1. The history of lead mining in 31 2.2.2. Mining and processing techniques 32 2.2.3. Mining production records 39 2.3. The impact of metal mining on the River Swale system 42 2.3.1. The potential impacts of mining and processing 42 2.3.2. Investigations of floodplain contamination 43 2.3.2.1. Upland contamination patterns 43 2.3.2.2. Piedmont contamination patterns 44 2.3.2.3. Lowland contamination patterns 45 2.3.2.4. Summary of catchment-scale patterns 45 2.3.3. Investigations of channel sediment contamination 46 2.3.4. Summary and required research 48

CHAPTER 3 GEOCHEMICAL CHARACTERISATION OF FLUVIAL SEDIMENTS IN THE SWALE CATCHMENT 3.1. Introduction 50 3.2. Laboratory methods 51 3.2.1. Particle size selection 51 3.2.2. Initial sample preparation 51 3.2.3. Digestion procedure 52 3.2.4. ICP-MS analysis 54 3.3. Analytical Quality Control 55 3.3.1. Approaches to AQC 55 3.3.2. Quality control during sample collection 55 3.3.3. Quality control during sample preparation and analysis 56 3.3.4. Data quality: AQC results 57 3.4. Summary 58 iv Contents

CHAPTER 4 THE IMPACT OF METAL MINING ON HEADWATER TRIBUTARIES OF THE RIVER SWALE: THE BECK CATCHMENT 4.1. Introduction 59 4.2. Study Area: Gunnerside Beck 60 4.2.1. General characteristics 60 4.2.2. Catchment geology and mineralisation 60 4.2.3. Fluvial geomorphology 63 4.3. Mining in Gunnerside Beck 68 4.3.1. Mining history 68 4.3.2. The Blakethwaite mines 68 4.3.3. The Lownathwaite mines 70 4.3.4. The Old Gang mines 73 4.3.5. Sir Francis Level 74 4.3.6. Summary: The legacy of mining in Gunnerside Beck 75 4.4. The impact of mining on catchment geochemistry 76 4.4.1. Introduction 76 4.4.2. Methods 76 4.4.3. Patterns of metal dispersal in mine waste 76 4.4.4. Patterns of metal dispersal in floodplain sediments 80 4.4.5. Patterns of metal dispersal in channel sediments 87 4.4.6. Grain size partitioning 93 4.4.7. Summary: The geochemical legacy of mining in Gunnerside Beck 95 4.5. The impact of mining on fluvial geomorphology 98 4.5.1. Introduction 98 4.5.2. Morphological changes attributable to mining 98 4.5.3. Morphological changes since the cessation of mining 101 4.5.4. Summary: The geomorphological legacy of mining in Gunnerside Beck 103 4.7. Conclusion 103

CHAPTER 5 METAL DISTRIBUTION IN FLOODPLAIN SEDIMENT 5.1. Introduction 105 5.2. Methods 106 v Contents

5.3. Metal distribution patterns 109 5.3.1. Introduction 109 5.3.2. Downstream metal distribution patterns 110 5.3.3. Lateral metal distribution patterns 110 5.3.3.1. Hartlakes 110 5.3.3.2. 113 5.3.3.3. Hudswell 113 5.3.3.4. Brompton-on-Swale 116 5.3.3.5. 116 5.3.3.6. Morton Flatts 118 5.3.3.7. Fairholme 120 5.3.3.8. Maunby 121 5.3.3.9. Holme 122 5.3.3.10. Eldmire 123 5.3.3.11. Thornton Manor 124 5.3.3.12. Myton-on-Swale 124 5.3.3.13. Additional floodplain cores 124 5.3.4. Summary: Metal distribution patterns in floodplain sediments 127 5.4. Controls on metal distribution 127 5.4.1. Introduction 127 5.4.2. Longitudinal distribution patterns 128 5.4.3. Lateral distribution patterns 131 5.4.4. Metal distribution patterns with depth 140 5.4.5. Summary: Controls on metal distribution in floodplain sediments 140 5.5. Conclusion 141

CHAPTER 6 PATTERNS OF METAL DISTRIBUTION IN CONTEMPORARY FLOOD SEDIMENTS 6.1. Introduction 142 6.2. Methods 143 6.2.1. Recent floods in the Swale catchment 143 6.2.2. Flood sediment: sampling and analysis 144 6.2.3. Measuring overbank metal deposition 148 vi Contents

6.3. Metal distribution patterns in flood sediments 149 6.3.1. Introduction 149 6.3.2. October-December 2000 floods 150 6.3.2.1. Channel-edge sediment 150 6.3.2.2. Overbank sediment 150 6.3.3. November-December 2001 floods 153 6.3.3.1. Channel-edge sediment 153 6.3.3.2. Overbank sediment 153 6.3.4. January-February 2002 floods 155 6.3.4.1. Channel-edge sediment 155 6.3.4.2. Overbank sediment 157 6.3.5. Grain size partitioning in flood sediments 157 6.3.6 Metal deposition on the River Swale floodplain 161 6.3.7. Summary: Metal distribution patterns in flood sediments 164 6.4. Controls of downstream metal concentrations in flood sediments 168 6.4.1. Introduction 168 6.4.2. Downstream decline of metals on flood sediments 168 6.4.3. Sediment inputs 168 6.4.4. Geomorphological controls 172 6.4.5. The influence of flood magnitude on metal concentrations 175 6.4.6. Summary: Controls of downstream metal distribution in flood sediments 178 6.5. Conclusion 178

CHAPTER 7 METAL STORAGE IN THE RIVER SWALE CATCHMENT 7.1. Introduction 180 7.2. Metal storage in formerly mined tributaries 181 7.2.1. Introduction 181 7.2.2. Methods: Estimating metal storage in Gunnerside Beck 181 7.2.3. Metal storage in Gunnerside Beck 183 7.2.4. Potential metal storage in tributary sediments 188 7.2.5. Summary: Metal storage in tributary sediments 188 7.3. Metal storage in floodplain sediments 191 7.3.1. Introduction 191 vii Contents

7.3.2. Methods: Estimating floodplain metal storage 191 7.3.3. Metal storage in the River Swale floodplain 192 7.3.4. Summary: Metal storage in floodplain sediments 198 7.4. Metal storage and fluxes in the River Swale catchment 199 7.5. Conclusion 201

CHAPTER 8 ASSESSING THE ENVIRONMENTAL IMPACT OF MINING IN THE SWALE CATCHMENT 8.1. Introduction 202 8.2. Assessment using environmental quality guidelines 203 8.2.1. Environmental quality guidelines in the U.K 203 8.2.2. Comparison with U.K guidelines 206 8.2.3. Limitations of existing guidelines 212 8.3. Assessing using background concentrations 213 8.3.1. Approaches to background determination 213 8.3.2. Determining background metal concentrations in the Swale catchment 215 8.3.3. Comparison with background concentrations 221 8.3.4. Limitations of estimating background concentrations 225 8.4. Environmental impacts of metal enrichment 227 8.4.1. Implications of metal enrichment in fluvial sediments 227 8.4.2. Potential management strategies 229 8.5. Conclusion: The environmental impact of metal mining 231

CHAPTER 9 CONCLUSIONS 9.1. Summary of findings 233 9.1.1. Metals in tributary sediments 233 9.1.2. Metals in floodplain sediments 234 9.1.3. Metals in flood sediments 234 9.1.4. Metal storage in the Swale catchment 235 9.1.5. The environmental impact of mining 235 9.2. Overall conclusions 236 viii Contents

9.3. Implications 236 9.4. Recommendations for further research 238

BIBLIOGRAPHY 240 APPENDIX 1: GUNNERSIDE BECK DATA 257 APPENDIX 2: FLOODPLAIN SEDIMENT DATA 261 APPENDIX 3: FLOOD SEDIMENT DATA 267

ix List of figures

LIST OF FIGURES

CHAPTER 2 Figure 2.1: The River Swale catchment, showing drainage network and major 19 tributaries Figure 2.2: Geology of the Swale catchment 21 Figure 2.3: The distribution of mineral veins in the Swale catchment 22 Figure 2.4: Geomorphological characteristics of the River Swale 26 Figure 2.5: Location and output of Pb mines in Swaledale 32 Figure 2.6: The ore dressing process employed in Swaledale Pb mines 35 Figure 2.7: Location of smelters and dressing floors in Swaledale 38 Figure 2.8: Total Pb production by tributary 41 Figure 2.9: Metal contamination in River Swale channel sediments 47

CHAPTER 3

Figure 3.1: Flow chart detailing the HNO3 digestion procedure used in this 53 investigation

CHAPTER 4 Figure 4.1: Map of the Gunnerside Beck catchment, showing drainage network, 61 relief, and location of mines, dressing floors and smelters Figure 4.2: Major mineral veins in the Gunnerside catchment 62 Figure 4.3: Geomorphological characteristics of Gunnerside Beck 64 Figure 4.4: The Blakethwaite lead mines 69 Figure 4.5: The Lownathwaite and Old Gang mines 71 Figure 4.6: Sediment sample sites in Gunnerside Beck 77 Figure 4.7: Pb, Zn and Cd concentrations in 2000-63 µm Gunnerside Beck mine 81 spoil Figure 4.8: Pb, Zn and Cd concentrations in <63 µm Gunnerside Beck mine spoil 82

x List of figures

Figure 4.9: Pb, Zn and Cd concentrations in 2000-63 µm Gunnerside Beck 83 floodplain sediments Figure 4.10: Pb, Zn and Cd concentrations in <63 µm Gunnerside Beck floodplain 84 sediments Figure 4.11: Floodplain contamination schematic 88 Figure 4.12: Pb, Zn and Cd concentrations in 2000-63 µm Gunnerside Beck 89 channel sediments Figure 4.13: Pb, Zn and Cd concentrations in <63 µm Gunnerside Beck channel 90 sediments Figure 4.14: Grain size characteristics of Gunnerside Beck floodplain sediments, 94 channel sediments and mine spoil Figure 4.15: Gunnerside Beck 2000-63 µm concentrations, waste inputs and 96 catchment characteristics Figure 4.16: Gunnerside Beck <63 µm concentrations, waste inputs and catchment 97 characteristics

CHAPTER 5 Figure 5.1: Floodplain sediment study sites in the River Swale catchment 108 Figure 5.2: Downstream trends in metal dispersal 111 Figure 5.3: Floodplain metal concentrations and surface topography at Hartlakes 112 Figure 5.4: Floodplain metal concentrations and surface topography at Reeth 114 Figure 5.5: Floodplain metal concentrations and surface topography at Hudswell 115 Figure 5.6: Floodplain metal concentrations and surface topography at 117 Brompton-on-Swale Figure 5.7: Floodplain metal concentrations and surface topography at Great 118 Langton Figure 5.8: Floodplain metal concentrations and surface topography at Morton 119 Flatts Figure 5.9: Floodplain metal concentrations and surface topography at Fairholme 120 Figure 5.10: Floodplain metal concentrations and surface topography at Maunby 121 Figure 5.11: Floodplain metal concentrations and surface topography at Holme 122 Figure 5.12: Floodplain metal concentrations and surface topography at Eldmire 123 Figure 5.13: Floodplain metal concentrations and surface topography at Thornton 125 Manor

xi List of figures

Figure 5.14: Floodplain metal concentrations and surface topography at Myton- 126 on-Swale Figure 5.15: Pb concentration in floodplain and tributary sediments, and 129 geomorphological characteristics Figure 5.16: Floodplain metal concentrations and elevation 134 Figure 5.17: Simulated inundation frequency and floodplain metal concentrations 137 at Reeth Figure 5.18: Simulated inundation frequency and floodplain metal concentrations 138 at Brompton-on-Swale

CHAPTER 6 Figure 6.1: Mean, minimum and maximum daily discharge at Catterick Bridge 145 gauging station Figure 6.2: Map of the River Swale catchment, showing flood sediment sampling 146 sites and the location of major tributaries Figure 6.3: Pb, Zn and Cd concentrations in 2000 channel-edge flood sediment 151 Figure 6.4: Pb, Zn and Cd concentrations in 2000 overbank flood sediment 152 Figure 6.5: Pb, Zn and Cd concentrations in 2001 channel-edge flood sediment 154 Figure 6.6: Pb, Zn and Cd concentrations in 2001 overbank flood sediment 155 Figure 6.7: Pb, Zn and Cd concentrations in 2002 channel-edge flood sediment 156 Figure 6.8: Pb, Zn and Cd concentrations in 2002 overbank flood sediment 158 Figure 6.9: Grain size characteristics of channel-edge flood sediments 159 Figure 6.10: Grain size characteristics of overbank flood sediments 160 Figure 6.11: Overbank sediment and metal deposition along the River Swale 162 Figure 6.12: Pb concentrations in 2000, 2001 and 2002 flood sediments 165 Figure 6.13: Zn concentrations in 2000, 2001 and 2002 flood sediments 166 Figure 6.14: Cd concentrations in 2000, 2001 and 2002 flood sediments 167 Figure 6.15: Pb concentrations in channel-edge flood sediment, tributaries and 170 floodplain sediment, and geomorphological characteristics Figure 6.16: Pb concentrations in overbank flood sediment, tributaries and 171 floodplain sediment, and geomorphological characteristics

xii List of figures

CHAPTER 7 Figure 7.1: Estimating metal storage in tributary and floodplain sediments 182 Figure 7.2: Floodplain Pb storage in Gunnerside Beck 184 Figure 7.3: Likely maximum extent of floodplain metal storage in the Swale 194 catchment

CHAPTER 8 Figure 8.1: Swale tributary, floodplain and flood sediments and U.K. 208 environmental quality guidelines for Pb Figure 8.2: Swale tributary, floodplain and flood sediments and U.K. 209 environmental quality guidelines for Pb Figure 8.3: Swale tributary, floodplain and flood sediments and U.K. 210 environmental quality guidelines for Pb Figure 8.4: Cumulative frequency curves for Pb, Zn and Cd 218 Figure 8.5: Recalculated background population (F’) for Pb, Zn and Cd 220 Figure 8.6: Swale tributary, floodplain and flood sediments and background 222 concentrations for Pb Figure 8.7: Swale tributary, floodplain and flood sediments and background 223 concentrations for Pb Figure 8.8: Swale tributary, floodplain and flood sediments and background 224 concentrations for Pb

xiii List of tables

LIST OF TABLES

CHAPTER 2 Table 2.1: Flood frequency and magnitude in the Yorkshire Ouse basin, 28 reconstructed from instrumental records Table 2.2: Flood frequency and magnitude in the Yorkshire Ouse basin, 28 reconstructed from flood deposits Table 2.3: Recorded and estimated lead production 40 Table 2.4: Recorded production of lead metal and concentrates in the North 40 Swaledale Mineral Belt Table 2.5: Recorded production of lead metal and concentrates in the South 40 Swaledale mining zone

CHAPTER 3 Table 3.1: Sampling and analytical coefficient of variation data for tributary, 57 floodplain and flood sediments

CHAPTER 4 Table 4.1: Multiple regression results: The relationship between metal 86 concentrations and geomorphological parameters in Gunnerside Beck floodplain sediments Table 4.2: Multiple regression results: The relationship between metal 92 concentrations and geomorphological parameters in Gunnerside Beck channel sediments

CHAPTER 5 Table 5.1: Study reach characteristics 107 Table 5.2: Multiple regression results: The relationship between floodplain metal 130 concentrations and geomorphological parameters

xiv List of tables

CHAPTER 6 Table 6.1: Multiple regression results: The relationship between metal 173 concentrations in channel-edge flood sediments and geomorphological parameters Table 6.2: Multiple regression results: The relationship between metal 174 concentrations in overbank flood sediments and geomorphological parameters

CHAPTER 7 Table 7.1: Estimated storage of Pb in formerly mined tributaries 189 Table 7.2: Estimated storage of Pb in floodplain sediments 193

CHAPTER 8 Table 8.1: U.K. metal concentration guidelines for Pb, Zn and Cd 205 Table 8.2: Percentage failure of environmental quality guidelines 207 Table 8.3: Descriptive statistics for fluvial sediments from the Swale catchment 216 Table 8.4: Background concentrations for Pb, Zn and Cd in the Swale catchment 221 Table 8.5: Percentage of samples exceeding background metal concentrations 225

xv List of plates

LIST OF PLATES

CHAPTER 2 Plate 2.1: North Hush and Priscilla Level, Gunnerside Beck 34 Plate 2.2: Bouse teams, Old Gang Company dressing floor, Sir Francis Level, 34 Gunnerside Beck Plate 2.3: Water-powered crusher, Bunton Level, Gunnerside Beck 36 Plate 2.4: Surrender smelt mill, Barney Beck 39

CHAPTER 4 Plate 4.1: The upper reaches of Gunnerside Beck 65 Plate 4.2: Floodplain deposits downstream of the Old Gang and Lownathwaite 65 mines Plate 4.3: Floodplain deposits and the AD Company dressing floor at Sir Francis 66 Level Plate 4.4: Blakethwaite smelter and the Blind Gill – Gunnerside Beck confluence 70 Plate 4.5: Sun Hush and North Hush 72 Plate 4.6: Bouse teams and the remains of a crushing mill at Bunton Level 74 dressing floor Plate 4.7: Channel braiding upstream of the Old Gang and Lownathwaite hushes 100 Plate 4.8: Braid bars and chutes downstream of the Old Gang and Lownathwaite 100 hushes Plate 4.9: Eroding bank section showing mining-related floodplain development 101

CHAPTER 6 Plate 6.1: Overbank sediments deposited in January-February 2002 147

xvi