The Periglaciation of Great Britain Colin K

Cambridge University Press 978-0-521-31016-1 - The Periglaciation of Great Britain Colin K. Ballantyne and Charles Harris Table of Contents More information

Contents

Preface related ground-ice features 70 Thermokarst depressions 71 PART 1: Introduction and context Morphological evidence of Pleistocene 1 Introduction 3 pingos and related cryogenic mounds 73 Evidence for Pleistocene pingos and The development of periglacial research in related cryogenic mounds in Britain 74 Great Britain 4 Large thermokarst depressions 80 Approaches to synthesis: the organisation of The significance of ground-ice this book 7 phenomena in Britain: an evaluation 82 2 Quaternary environmental change in Great Britain 11 6 Active layer processes: cryoturbation The Anglian glacial stage 11 and patterned ground 85 Glaciation between the Hoxnian and Active layer processes 85 Ipswichian Interglacials ('Wolstonian') 14 Patterned ground 89 The Early and Middle Devensian 14 Cryoturbation 94 The Late Devensian 1: The Dimlington Stadial 15 Quaternary patterned ground in lowland Britain 96 The Late Devensian 2: The Windermere Cryoturbation structures in lowland Britain 99 Interstadial 17 Pedological evidence for soil freezing and The Late Devensian 3: The Loch Lomond permafrost 109 Stadial 18 Summary 112 The Flandrian Interglacial 21 Present-day environmental conditions on 7 Periglacial mass wasting and slope evolution British mountains 22 in lowland Britain 113 Periglacial environments in space and time 24 The nature of thawing soils 113 3 Periglacial environments 27 Processes of periglacial mass wasting 114 Slow periglacial mass movements 114 Periglacial climates 27 Rapid mass movements 118 Vegetation 28 Ground-ice slumps 118 Soils 29 Permafrost creep 119 Fauna 30 Slopewash 120 Permafrost 31 Periglacial slope evolution in lowland Britain 120 PART 2: The periglaciation of lowland Britain 37 Periglacial slope deposits 121 Granular head deposits derived from 4 Ice-wedge casts and relict tundra polygons 39 nonargillaceous rocks 122 Ice-wedges, sand wedges and tundra polygons 39 Clay-rich head deposits 130 Mechanism of wedge casting and Granulometry and geotechnical properties characteristics of casts 44 of head deposits 134 Recognition of permafrost wedge casts 46 Thaw-induced periglacial landslides in Permafrost wedge casts and tundra bedrock 135 polygons in Great Britain 47 Relict ground-ice slumps 136 The stratigraphy of wedge casts and relict Slope evolution 136 tundra polygons 53 Cambering and valley bulging 137 The significance of wedge casts and Periglacial slope processes and landscape polygonal crop marks 62 evolution: concluding comments 140 5 Pingos and related ground-ice phenomena 65 8 Lowland landscape modification by fluvial Characteristics of active pingos 65 and aeolian processes 141 Other ice-cored mounds 68 Periglacial rivers and rivervalley s 141 The climatic significance of pingos and Pleistocene fluvial landforms and deposits 147

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CONTENTS

Wind action 155 12 Talus slopes and related landforms 219 The significance of periglacial fluvial and Rockfall talus slopes 219 aeolian activity 160 Avalanche-modified talus 226 Debris flow activity 227 3: The periglaciation of upland Britain 161 Protalus ramparts 236 Frost weathering and mountain-top detritus 163 Protalus rock glaciers 240 Periglacial weathering 163 Talus and related landforms: summary 244 Periglacial weathering in upland Britain 166 13 Nival, fluvial, aeolian and coastal features 245 Mountain-top detritus 173 Nivation and cryoplanation 245 Upland tors 178 The geomorphic role of running water 250 Periglacial trimlines 182 The action of wind 255 Mountain-top detritus and the distribution Shoreline erosion under periglacial conditions 267 of periglacial landforms 187 The significance of mountain-top detritus PART 4: Periglacial environments 273 on British mountains 190 14 Past and present periglacial environments 275 Patterned ground on British mountains 193 Periglacial environments during the Sorted patterned ground on British uplands 193 Dimlington Stadial 278 Nonsorted patterned ground in upland Britain 199 The periglacial environment of the Summary 203 Loch Lomond Stadial 286 Solifluction landforms in upland Britain 205 The present-day periglacial environment of upland Britain 292 Valley-floor solifluction terraces 205 Themes and prospects 297 Relict solifluction phenomena on the upper slopes of British mountains 208 References 299 Active solifluction phenomena 214 Solifluction landforms in upland Britain: Index 325 problems and potential 218