Coastal Geomorphology: An Introduction, 2nd Edition

Acknowledgements xiii

List of Figures xv

List of Tables and Panels xxiii

1 Introduction 01

1.1 Coastal geomorphology 01

1.2 Terminology 02

1.3 Ancient coastlines 03

1.4 Coastline morphology 05

1.5 Coastline length 07

1.6 Coastal evolution 08

1.7 Changing coastlines 09

1.8 Summary 11

2 Coastal processes 13

2.1 Introduction 13

2.2 Waves 13

2.3 Tides 25

2.4 Storm surges 31

2.5 Tsunamis 32

2.6 Currents 34

2.7 Nearshore water circulation 35

2.8 Wind action 36

2.9 Other processes 36

2.10 Modelling coastal processes 36

2.11 Summary 37

3 Land and sea level changes 39

3.1 Introduction 39

3.2 Mean sea level 39

3.3 Causes of sea level change 40

3.4 Measuring changes of level 45

3.5 Correlation and dating of former coastlines 46

3.6 Emerged coastlines 46

3.7 Submerged coastlines 51

3.8 Sea level variations 53

3.9 Late Quaternary sea level changes 53

3.10 Modern sea level changes 58

3.11 Recent changes of land and sea level 62

3.12 Future sea level changes 65

3.13 Summary 66

4 Cliffs 67

4.1 Introduction 67

4.2 Cliff evolution 69

4.3 Cliff morphology 74

4.4 Cliff weathering in cold climates 85

4.5 Cliffs and bluffs on humid tropical coasts 86

4.6 Cliff dissection 87

4.7 Outlines in plan of cliffed coasts 95

4.8 Coastal landslides 98

4.9 Rates of cliff recession 102

4.10 Summary 106

5 Shore platforms 107

5.1 Shore processes 107

5.2 Shore platforms 113

5.3 Plunging cliffs 130

5.4 Summary 132

6 Beaches 133

6.1 Introduction 133

6.2 Beach sediments 134

6.3 Evolution of beaches 137

6.4 Provenance of beach sediments 138

6.5 Weathering of beach material 160

6.6 Beach rock 161

6.7 Nearshore processes 162

6.8 Beach morphology 162

6.9 Beach outlines in plan 164

6.10 Beach outlines in profile 171

6.11 Beach morphodynamics and beach states 179

6.12 Use of models 181

6.13 Beach compartments 182

6.14 Beach budgets 183

6.15 Tracing beach sediment flow 184

6.16 Lateral grading 187

6.17 Prograding beaches 190

6.18 Beach ridges 193

6.19 Cheniers 197

6.20 Beach lobes 198

6.21 Summary 200

7 Beach erosion 201

7.1 Introduction 201

7.2 The multiple causes of beach erosion 217

7.3 Effects of artificial structures on beaches 218

7.4 Beach nourishment 219

7.5 Summary 221

8 Spits, barriers and bars 223

8.1 Introduction 223

8.2 Spits 223

8.3 Tombolos 229

8.4 Cuspate and lobate spits 230

8.5 Cuspate and lobate forelands 234

8.6 Coastal barriers and barrier islands 235

8.7 Intertidal sandflats 242

8.8 Bars and troughs 242

8.9 Sand shoals 245

8.10 Ripples 245

8.11 Sandstone reefs 246

8.12 Summary 246

9 Coastal dunes 247

9.1 Introduction 247

9.2 Foredunes 250

9.3 Backshore cliffing of dunes 252

9.4 Parallel dunes 253

9.5 Blow-outs and parabolic dunes 255

9.6 Transgressive dunes 258

9.7 Cliff-top dunes 261

9.8 Dunes on shingle 261

9.9 Rates of dune movement 262

9.10 Dune calcarenite 263

9.11 Machair 265

9.12 Coastal dunes in the humid tropics 266

9.13 Old and new dunes 267

9.14 Dune sandrock 268

9.15 Dune lakes 268

9.16 Summary 268

10 Intertidal wetlands 271

10.1 Introduction 271

10.2 Intertidal morphology 271

10.3 Sources of intertidal sediments 274

10.4 Mudflats 274

10.5 Intertidal vegetation 276

10.6 Sea-grass beds 276

10.7 Salt marshes 277

10.8 Mangroves 286

10.9 Freshwater swamps 293

10.10 Summary 294

11 Estuaries and lagoons 295

11.1 Introduction 295

11.2 Rias 295

11.3 Fiords 296

11.4 Fiards 298

11.5 Calanques 298

11.6 Sharms and sebkhas 298

11.7 Estuaries 299

11.8 Coastal lagoons 311

11.9 Summary 329

12 Deltas 331

12.1 Introduction 331

12.2 Delta components 331

12.3 Deltaic processes 332

12.4 The Mississippi delta 334

12.5 Delta outlines 337

12.6 Delta evolution 342

12.7 Delta shores 346

12.8 Summary 347

13 Coral and algal reefs 349

13.1 Introduction 349

13.2 Coral reefs 349

13.3 Origin of coral reefs 350

13.4 Rates of growth 351

13.5 Fringing reefs 353

13.6 Barrier reefs 354

13.7 Atolls 357

13.8 Emerged coral reefs 359

13.9 Islands on coral reef platforms 360

13.10 Algal and other biogenic reefs 363

13.11 Summary 364

14 Future coasts 365

14.1 Introduction 365

14.2 Greenhouse effect and sea level rise 365

14.3 General effects of a rising sea level 366

14.4 Effects of a changing climate 369

14.5 Effects on cliffs and shore platforms 369

14.6 Effects on beaches, spits and barriers 372

14.7 Effects on coastal dunes 376

14.8 Effects on intertidal wetlands 376

14.9 Effects on estuaries and lagoons 379

14.10 Effects on deltaic coasts 380

14.11 Effects on coral and algal reefs 381

14.12 Conclusion 385

14.13 Summary 385

References 387

Index 405