An Introduction to Physical Geography and the Environment, Fourth Edition
By Joseph Holden
Contents:
Preface to the fourth edition xv
Contributors xvii
Editor’s acknowledgements xviii
Acknowledgements xix
Part I: The role of physical geography 1
1 Approaching physical geography 3
1.1 Introduction 3
1.2 Historical development of physical geography 5
1.2.1 Physical geography before 1800 5
1.2.2 Physical geography between 1800 and 1950 6
1.2.3 Physical geography since 1950 8
1.3 Scientific methods 10
1.3.1 The positivist method 10
1.3.2 Critique of the positivist method 11
1.3.3 Realism as an alternative positivist approach 12
1.3.4 Benefits of multiple scientific methods in physical geography 13
1.4 The field, the laboratory and the model 14
1.4.1 Approaching data collection from the environment 14
1.4.2 Approaching laboratory work 16
1.4.3 Approaching numerical modelling 16
1.5 Using physical geography for managing the environment 20
1.6 Summary 25
Further reading 26
Part II: Continents and oceans 27
2 Earth geology and tectonics 29
2.1 Introduction 29
2.2 The Earth’s structure 30
2.2.1 The interior of the Earth 30
2.2.2 The outer layers of the Earth 30
2.3 Rock type and formation 31
2.3.1 Igneous rock 31
2.3.2 Sedimentary rock 31
2.3.3 Metamorphic rock 33
2.3.4 The rock cycle 33
2.4 History of plate tectonics 33
2.4.1 Early ideas of global tectonics 33
2.4.2 Evidence that led directly to plate tectonic theory 34
2.5 The theory of plate tectonics 37
2.5.1 Lithospheric plates 37
2.5.2 Rates of plate movement 38
2.6 Structural features related directly to motion of the plates 39
2.6.1 Divergent plate boundaries 39
2.6.2 Transform faults 41
2.6.3 Convergent plate boundaries 42
2.6.4 Hot spots 50
2.7 The history of the continents 51
2.8 Summary 52
Further reading 52
3 Oceans 53
3.1 Introduction 53
3.2 The ocean basins 54
3.2.1 The scale of the oceans 54
3.2.2 Geological structure of the ocean basins 54
3.2.3 The depth and shape of the ocean basins 55
3.3 Physical properties of the ocean 55
3.3.1 Salinity 55
3.3.2 Temperature structure of the oceans 59
3.4 Ocean circulation 60
3.4.1 Surface currents 60
3.4.2 The deep currents of the oceans 62
3.4.3 The weather of the ocean 64
3.5 Sediments in the ocean 65
3.6 Biological productivity 67
3.6.1 Photosynthesis in the ocean 67
3.6.2 Importance of nutrient supply to primary productivity 68
3.6.3 Animals of the sea 69
3.6.4 Pollution 73
3.7 Effect of global climate change on the oceans 74
3.8 Summary 75
Further reading 76
Part III: Past, present and future climate and weather 77
4 The Pleistocene 79
4.1 Introduction 79
4.2 Long-term cycles, astronomical forcing and feedback mechanisms 81
4.2.1 Orbital forcing theory 81
4.2.2 Evidence that orbital forcing causes climate change 82
4.2.3 Problems with orbital forcing theory 85
4.2.4 Internal feedback mechanisms 85
4.3 Short-term cycles 89
4.3.1 Glacial instability 89
4.3.2 The Younger Dryas 90
4.4 Further evidence for environmental change 91
4.4.1 Landforms 92
4.4.2 Plants 97
4.4.3 Insects 98
4.4.4 Other animal remains 99
4.5 Dating methods 100
4.5.1 Age estimation techniques 100
4.5.2 Age equivalent labels 101
4.5.3 Relative chronology 101
4.6 Pleistocene stratigraphy and correlation 101
4.7 Palaeoclimate modelling 105
4.8 Summary 106
Further reading 107
5 The Holocene 108
5.1 Introduction 108
5.2 Holocene climatic change 109
5.2.1 How the Holocene began 109
5.2.2 Drivers of climate change during the
Holocene 110
5.2.3 The Little Ice Age 116
5.3 Holocene geomorphological change 117
5.3.1 Retreating ice sheets 117
5.3.2 Rising seas 118
5.4 Holocene ecosystem change 120
5.4.1 Responses of ecosystems to the end of the last
glacial 120
5.4.2 Tropical Africa and the Sahara 122
5.4.3 European ecosystems 123
5.4.4 Island ecosystems 124
5.5 The rise of civilizations 125
5.5.1 Humans at the end of the last glacial 125
5.5.2 The beginnings of agriculture 126
5.5.3 Social and environmental consequences of
agriculture 127
5.6 Human interaction with physical geography 128
5.6.1 Out of Eden? 128
5.6.2 Deforestation 128
5.6.3 Soil erosion and impoverishment 132
5.6.4 Irrigation and drainage 133
5.7 Summary 135
Further reading 136
6 Atmospheric processes 137
6.1 Introduction 137
6.2 The basics of climate 139
6.3 The global atmospheric circulation 141
6.4 Radiative and energy systems 142
6.4.1 The nature of energy 142
6.4.2 Distinguishing between temperature and
heat 144
6.4.3 Radiation 144
6.4.4 Thermal inertia 149
6.4.5 The atmospheric energy balance 150
6.5 Moisture circulation systems 150
6.5.1 Moisture in the atmosphere and the hydrological
cycle 150
6.5.2 Global distribution of precipitation and
evaporation 151
6.5.3 The influence of vegetation on evaporation 153
6.5.4 Drought 153
6.6 Motion in the atmosphere 154
6.6.1 Convective overturning 154
6.6.2 The Earth’s rotation and the winds 155
6.6.3 Long waves, Planetary Waves and Rossby
Waves 156
6.6.4 Jet streams 159
6.7 The influence of oceans and ice on atmospheric
processes 161
6.8 The Walker circulation 163
6.8.1 El Nino Southern Oscillation 164
6.8.2 North Atlantic Oscillation 166
6.9 Interactions between radiation, atmospheric trace
gases and clouds 167
6.9.1 The greenhouse effect 167
6.9.2 A simple climate model of the enhanced
greenhouse effect 167
6.9.3 Radiative interactions with clouds and sulfate
aerosols 170
6.10 Geoengineering 173
6.11 Summary 174
Further reading 174
7 Contemporary climate change 175
7.1 Introduction 175
7.2 Climate change 176
7.2.1 Long-term change 176
7.2.2 Recent climate change and its causes 177
7.2.3 Predictions from global climate models (GCMs) 180
7.2.4 Critical evaluation of the state-of-the-art in
GCMs 182
7.3 The carbon cycle: interaction with the climate
system 184
7.4 Mitigation 186
7.5 Destruction of the ozone layer by chlorofluorocarbons
(CFCs) 187
7.6 The future 189
7.7 Summary 193
Further reading 194
8 Global climate and weather 195
8.1 Introduction 195
8.2 General controls of global climates 196
8.3 The tropics and subtropics 201
8.3.1 Equatorial regions 201
8.3.2 The Sahel and desert margins 209
8.3.3 Subtropical deserts 210
8.3.4 Humid subtropics 211
8.4 Mid and high-latitude climates 215
8.4.1 Depressions, fronts and anticyclones 215
8.4.2 Mid-latitude western continental margins 219
8.4.3 Mid-latitude east continental margins and
continental interiors 220
8.5 Polar climates 221
8.6 A global overview 222
8.7 Summary 228
Further reading 228
9 Regional and local climates 229
9.1 Introduction 229
9.2 Altitude and topography 230
9.2.1 Pressure 233
9.2.2 Temperature 233
9.2.3 Wind 234
9.2.4 Precipitation 235
9.2.5 Frost hollows 240
9.3 Influence of water bodies 240
9.4 Human influences 242
9.4.1 Shelter belts 242
9.4.2 Urban climates 243
9.4.3 Atmospheric pollution and haze 246
9.5 Summary 248
Further reading 249
Part IV: Biogeography and ecology 251
10 The biosphere 253
10.1 Introduction 253
10.2 Biological concepts 254
10.2.1 What is a species? 254
10.2.2 The naming of species 254
10.2.3 Levels of organization 255
10.2.4 Biodiversity 255
10.3 Patterns of distribution 258
10.3.1 Potential species distributions 258
10.3.2 Actual species distributions 259
10.3.3 Spatial patterns in biodiversity 260
10.4 Terrestrial biomes 261
10.4.1 Equatorial and tropical forests 262
10.4.2 Savanna 265
10.4.3 Hot Desert 266
10.4.4 Mediterranean-type biome 266
10.4.5 Temperate grassland 268
10.4.6 Temperate broadleaf forest 268
10.4.7 Taiga 269
10.4.8 Tundra 270
10.5 Aquatic biomes 272
10.5.1 Marine regions 272
10.5.2 Freshwater regions 274
10.6 Summary 275
Further reading 276
11 Ecosystem processes 277
11.1 Introduction 277
11.2 The flow of energy and resources 278
11.2.1 Energy entering an ecosystem 278
11.2.2 Ecological thermodynamics 278
11.2.3 Trophic levels and food webs 279
11.2.4 Biogeochemical cycles 280
11.3 Biotic interactions 281
11.3.1 Mutualism 282
11.3.2 Herbivory, predation and parasitism 282
11.3.3 Commensalism 283
11.3.4 Amensalism 284
11.3.5 Competition 284
11.4 Temporal change in ecosystems 285
11.4.1 Short-term changes 285
11.4.2 Disturbance and resilience 286
11.4.3 Succession 286
11.5 Human impact 289
11.5.1 Degrading ecosystems 289
11.5.2 Urban ecology 294
11.5.3 Conservation 294
11.6 Summary 297
Further reading 297
12 Freshwater ecosystems 298
12.1 Introduction 298
12.2 Running waters: rivers and streams 300
12.2.1 River ecosystem geomorphological units 300
12.2.2 Spatial variability of river ecosystems 302
12.2.3 Temporal variability of river ecosystems 308
12.2.4 Human alterations to river ecosystems 308
12.3 Still waters: lakes and ponds 312
12.3.1 Classification of lake ecosystems 312
12.3.2 Spatial variability of lake ecosystems 315
12.3.3 Human influences on lake ecosystems 319
12.4 Summary 321
Further reading 322
13 Vegetation and environmental change 323
13.1 Introduction 323
13.2 Fundamentals of how plants respond to climatic
variations 324
13.2.1 Light 324
13.2.2 Water 326
13.2.3 Temperature 326
13.2.4 Carbon dioxide concentration 327
13.2.5 Other climatic variables 327
13.3 Observational studies: how we know for sure that
vegetation responds to a changing climate 327
13.3.1 The forest/savanna boundary in southern
Amazonia 327
13.3.2 The northern tree line 329
13.3.3 Upward march of vegetation in mountains 329
13.3.4 Changes in the timing of flowering 330
13.4 Models for prediction 332
13.5 The complex interaction between human activities and
climate change 336
13.5.1 Does atmospheric pollution sometimes benefit
plants? 336
13.5.2 How does fire interact with climate change? 336
13.6 Loss of biodiversity 340
13.7 Agriculture and food security 341
13.8 Summary 343
Further reading 343
Part V: Geomorphology and hydrology 345
14 Weathering 347
14.1 Introduction 347
14.2 Environmental and material controls on weathering 348
14.3 Weathering and the role of water 350
14.4 Chemical weathering 352
14.4.1 Hydrolysis 352
14.4.2 Carbonation 352
14.4.3 Solution 353
14.4.4 Oxidation and reduction 353
14.4.5 Biologically related chemical weathering 353
14.4.6 Products of chemical weathering 354
14.5 Physical weathering 356
14.5.1 Dilatation – pressure release 356
14.5.2 Thermoclasty 358
14.5.3 Freeze–thaw (frost weathering) 359
14.5.4 Salt weathering 359
14.5.5 Biologically related physical weathering 363
14.6 Climatic controls on weathering 364
14.7 Geological controls on weathering 367
14.8 Urban stone decay and lessons for rock
weathering 371
14.8.1 Stone decay is multifactorial 373
14.8.2 Rates of stone decay are unpredictable 373
14.8.3 Decay is spatially variable 374
14.8.4 Stress history is important 375
14.9 Summary 375
Further reading 376
15 Slope processes and landform evolution 377
15.1 Introduction 377
15.2 Slope profiles 378
15.2.1 Slope length 378
15.2.2 Slope steepness 378
15.2.3 Slope convexity 380
15.3 Hillslope transport processes 380
15.3.1 Chemical transport processes (solution) 381
15.3.2 Physical transport processes 382
15.3.3 Biological mixing 390
15.3.4 Particle movements 390
15.3.5 The balance between erosion processes 396
15.4 Evolution of hillslope profiles 398
15.4.1 Concepts 398
15.4.2 Models 401
15.4.3 Interpreting landscape form 405
15.5 Summary 406
Further reading 406
16 Sediments and sedimentation 407
16.1 Introduction 407
16.2 Clastic sediments 408
16.2.1 Classification of clastic sediments 408
16.2.2 Clastic sediment grain shape and texture 409
16.2.3 Sediment transport and sedimentation 409
16.2.4 Products of sedimentation – bedforms 412
16.3 Biological sediments 415
16.4 Chemical sediments 417
16.5 Sedimentation in Earth surface environments 418
16.5.1 Continental environments 418
16.5.2 Coastal and marine environments 420
16.6 Response of sedimentation to environmental
change 422
16.6.1 Dams and reservoirs 424
16.6.2 Mining 424
16.6.3 Urbanization 425
16.6.4 Sediment management 426
16.7 Summary 427
Further reading 428
17 Soils 429
17.1 Introduction 429
17.2 The components of soil 430
17.2.1 Mineral particles 430
17.2.2 Soil organic matter 430
17.2.3 Soil water 431
17.2.4 Soil air 432
17.3 Soil profile 433
17.4 Soil formation processes 434
17.4.1 Pedogenesis 434
17.4.2 Factors affecting soil formation 437
17.5 Physical properties of soil 441
17.5.1 Soil colour 441
17.5.2 Soil texture 441
17.5.3 Soil structure 444
17.6 Chemical properties of soil 445
17.6.1 Clay minerals and cation exchange 445
17.6.2 Soil acidity 447
17.7 Soil biology 449
17.7.1 The soil biota 449
17.7.2 Factors influencing soil biodiversity 451
17.8 Impact of human activities on soils and soil
processes 452
17.8.1 Soil erosion 452
17.8.2 Soil acidification 453
17.8.3 Soil pollution 454
17.8.4 Soil organic matter and carbon 456
17.8.5 Other threats 458
17.8.6 Policy and legislation 462
17.9 Summary 463
Further reading 464
18 Catchment hydrology 465
18.1 Introduction 465
18.2 Measuring the main components of catchment
hydrology 466
18.2.1 Precipitation 466
18.2.2 River flow 468
18.2.3 Evapotranspiration 472
18.2.4 Soil water 473
18.2.5 Groundwater 475
18.3 Flow paths to water bodies 476
18.3.1 Infiltration 476
18.3.2 Infiltration-excess overland flow 476
18.3.3 Saturation-excess overland flow 477
18.3.4 Throughflow 478
18.4 River discharge 483
18.4.1 Stormflow 483
18.4.2 Flow frequency 485
18.4.3 River regime 488
18.5 Flooding 489
18.6 Summary 491
Further reading 491
19 Fluvial geomorphology and river
management 493
19.1 Introduction 493
19.2 Catchment processes: energy and materials for
rivers 494
19.2.1 Runoff, river regimes and floods 494
19.2.2 Sediment sources and delivery 495
19.3 River channel morphology: measuring rivers 496
19.3.1 Channel networks and slope 496
19.3.2 Channel cross-section: width, depth 497
19.3.3 Channel planform 497
19.3.4 Channel boundary materials 498
19.4 River channel processes: understanding water and
sediment movement 499
19.4.1 Water flow and flow hydraulics 499
19.4.2 Sediment movement 500
19.5 River channels: linking channel processes and
morphology 502
19.5.1 Long profile 504
19.5.2 River channel cross-sections 505
19.5.3 Channel planform 505
19.5.4 Channel bed morphology 507
19.6 River channel changes: rates and types of channel
adjustment 509
19.6.1 Cross-sectional change 511
19.6.2 Planform change 511
19.6.3 Human-induced change 513
19.7 Fluvial geomorphology and environmentally sound river
management: living and working with nature 515
19.7.1 River management and the engineering
tradition 515
19.7.2 Living with rivers 516
19.7.3 River maintenance 517
19.7.4 Building new river channels 519
19.7.5 River restoration 520
19.8 Summary 523
Further reading 524
20 Solutes and water quality 525
20.1 Introduction 525
20.2 Solutes: some key controls 526
20.2.1 Solute form 526
20.2.2 pH and redox potential 526
20.2.3 Temperature and pressure 528
20.2.4 The role of particulates 529
20.2.5 Solute fluxes 529
20.3 Solutes within the catchment hydrological system 530
20.3.1 Precipitation 530
20.3.2 Evapotranspiration and evaporation 532
20.3.3 Interception 533
20.3.4 Soil 533
20.3.5 Groundwater 535
20.3.6 Rivers 536
20.3.7 Lakes and reservoirs 536
20.4 The role of hydrological pathways in solute
processes 538
20.5 Temporal patterns of solutes 540
20.5.1 Patterns of solutes in storm events: short-term
changes 541
20.5.2 Annual patterns of solute concentrations 542
20.5.3 Long-term patterns of solute
concentrations 544
20.6 Spatial patterns of solutes 548
20.6.1 Global patterns of solutes 549
20.6.2 Regional patterns of solutes 549
20.7 Modelling solutes and water quality 553
20.7.1 Modelling solutes in catchments 553
20.7.2 Modelling solutes in watercourses 553
20.8 Summary 555
Further reading 556
21 Drylands 557
21.1 Introduction 557
21.2 Aridity 560
21.2.1 Drylands 560
21.2.2 Causes of aridity 561
21.3 Dryland soil and vegetation systems 563
21.3.1 Dryland soils 563
21.3.2 Dryland vegetation 563
21.4 Geomorphological processes in drylands 566
21.4.1 Dryland landscapes 566
21.4.2 Rock weathering in drylands 567
21.4.3 Hillslope and channel processes 568
21.4.4 Aeolian processes and forms 571
21.5 Environmental change in drylands 578
21.6 Summary 582
Further reading 583
22 Coasts 584
22.1 Introduction 584
22.2 Coastal morphodynamics 588
22.3 Coastal processes: waves 590
22.3.1 Linear wave theory 591
22.3.2 Wave processes in intermediate water 592
22.3.3 Wave processes in shallow water 593
22.3.4 Nearshore currents 595
22.4 Coastal processes: storm surge, tides and tsunami 597
22.4.1 Storm surge 597
22.4.2 Tides 598
22.4.3 Tsunami 600
22.5 Coastal classification 600
22.6 Wave-dominated coastal environments 601
22.6.1 Barriers 601
22.6.2 Beaches 602
22.6.3 Coastal dunes 605
22.7 Tide-dominated coastal environments 608
22.7.1 Wave- and tide-dominated estuaries 608
22.7.2 Estuarine mixing 611
22.7.3 Ebb- and flood-dominance 613
22.7.4 Salt marsh and mangroves 613
22.8 Fluvial-dominated coastal environments 614
22.9 Erosive coasts 617
22.9.1 Rocky coast processes 617
22.9.2 Coastal cliffs 619
22.9.3 Shore platforms 619
22.10 Coastal zone management 620
22.11 Summary 623
Further reading 624
23 Glaciers and ice sheets 625
23.1 Introduction 625
23.2 Glaciology 626
23.2.1 Types of ice mass 626
23.2.2 Where do glaciers occur? 627
23.2.3 Glacier mass balance 628
23.2.4 Transformation of snow into ice 631
23.2.5 Glacier thermal regime 631
23.2.6 Glacier water systems 632
23.2.7 Glacier dynamics 636
23.3 Glacial geological processes and
glacial sediments 644
23.3.1 Processes of glacial erosion 644
23.3.2 Entrainment and transport 645
23.3.3 Deposition 647
23.4 The record of glacial change 650
23.4.1 Ice sheet reconstruction 650
23.5 Summary 654
Further reading 655
24 Permafrost and periglaciation 656
24.1 Introduction 656
24.2 Permafrost processes 657
24.2.1 The distribution of permafrost 657
24.2.2 Ground temperatures and permafrost thickness 659
24.2.3 Reconstructing climate change from permafrost temperatures 659
24.2.4 Gas hydrates 661
24.2.5 Hydrology in permafrost regions 663
24.3 Geomorphology of permafrost and periglacial environments 665
24.3.1 Ground ice features 665
24.3.2 Slope processes 670
24.3.3 Loess and aeolian activity 673
24.4 Summary 673
Further reading 674
Part VI: Monitoring and management 675
25 Monitoring environmental change 677
25.1 Introduction 677
25.2 In situ data 678
25.2.1 Satellite positioning systems 678
25.2.2 Telemetry 679
25.2.3 Environmental sensor networks 679
25.3 Remote sensing date 680
25.3.1 Platforms 682
25.3.2 Electromagnetic radiation 682
25.3.3 Image data 684
25.4 Camera sensors 689
25.4.1 Photogrammetry 691
25.5 Multispectral, thermal and hyperspectral sensors 693
25.5.1 Landsat 695
25.5.2 Spot 698
25.5.3 NASA’s Earth Observing System
Program 699
25.5.4 High-resolution sensors 701
25.6 Microwave and ranging sensors 701
25.6.1 Microwave sensors 701
25.6.2 Ranging sensors 705
25.7 Digital image processing 710
25.7.1 Digital images 710
25.7.2 Image rectification 711
25.7.3 Image enhancement 712
25.8 Summary 718
Further reading 718
26 Dealing with hazards and environmental change 719
26.1 Introduction 719
26.2 Types of environmental hazard 720
26.3 Characteristics of environmental change 722
26.3.1 The nature of change 722
26.3.2 Rate of change 724
26.3.3 Environmental tolerance 725
26.4 Prediction 725
26.4.1 Monitoring 725
26.4.2 Modelling 726
26.4.3 Uncertainty 727
26.5 Risk and vulnerability 727
26.6 Management tools 727
26.6.1 Mitigation 729
26.6.2 Adaptation 729
26.6.3 Impact assessment 729
26.6.4 Life costing 730
26.6.5 Ecosystem services 732
26.6.6 Engagement 732
26.7 Summary 734
Further reading 735
Glossary 736
Bibliography 763
Index 795