Physical geology / 10th ed.

Chapter 1
Introduction to Physical Geology 3
Who Needs Geology? 4
Avoiding Geologic Hazards 6
Supplying Things We Need 7
Protecting the Environment 8
Understanding Our Surroundings 8
An Overview of Physical Geology-Important Concepts 10
Internal Processes: How the Earth's Internal Heat Engine Works 12
The Earth's Interior 12
The Theory of Plate Tectonics 12
Surficial Processes: The Earth's External Heat Engine 16
Geologic Time 19
Summary 21
Terms to Remember* 21
Testing Your Knowledge* 22
Expanding Your Knowledge* 22
Exploring Web Resources* 23
Animations* 23
Chapter 2
Atoms, Elements, and Minerals 25
Atoms and Elements 26
Chemical Activity 28
Ions 29
Chemical Composition of the Earth's Crust 29
Crystallinity 31
The Silicon-Oxygen Tetrahedron 32
Minerals 35
Crystalline Solids 35
Natural and Inorganic Substances 35
Definite Chemical Composition 35
The Important Minerals 36
The Physical Properties of Minerals 38
Color 38
Streak 38
Luster 38
Hardness 38
External Crystal Form 39
Cleavage 40
Fracture 41
Specific Gravity 43
Special Properties 43
Other Properties 43
Chemical Tests 44
Summary 45
Chapter 3
Igneous Rocks, Intrusive Activity, and the Origin of Igneous Rocks 49
The Rock Cycle 50
A Plate Tectonic Example 50
Igneous Rocks 51
Igneous Rock Textures 52
Identification of Igneous Rocks 52
Varieties of Granite 54
Chemistry of Igneous Rocks 54
Intrusive Bodies 57
Shallow Intrusive Structures 57
Intrusives That Crystallize at Depth 58
Abundance and Distribution of Plutonic Rocks 60
How Magma Forms 61
Heat for Melting Rock 61
Factors That Control Melting Temperatures 61
How Magmas of Different Compositions Evolve 62
Sequence of Crystallization and Melting 63
Differentiation 64
Partial Melting 64
Assimilation 65
Mixing of Magmas 65
Explaining Igneous Activity by Plate Tectonics 66
Igneous Processes at Divergent Boundaries 66
Intraplate Igneous Activity 66
Igneous Processes at Convergent Boundaries 67
Summary 70
Chapter 4
Volcanism and Extrusive Rocks 75
Effects on Humans 77
The Growth of Hawaii 77
Geothermal Energy 77
Effect on Climate 77
Volcanic Catastrophes 79
Eruptive Violence and Physical Characteristics of Lava 80
Extrusive Rocks and Gases 82
Scientific Investigation of Volcanism 82
Gases 82
Extrusive Rocks 84
Types of Volcanoes 87
Shield Volcanoes 88
Cinder Cones 89
Composite Volcanoes 89
Volcanic Domes 94
Lava Floods 96
Submarine Eruptions 97
Pillow Basalts 98
Summary 99
Chapter 5
Weathering and Soil 103
Weathering, Erosion, and Transportation 104
How Weathering Alters Rocks 104
Effects of Weathering 104
Mechanical Weathering 106
Frost Action 106
Pressure Release 106
Other Processes 107
Chemical Weathering 109
Role of Oxygen 109
Role of Acid 109
Solution Weathering 111
Chemical Weathering of Feldspar 111
Chemical Weathering of Other Minerals 112
Weathering and Climate 113
Weathering Products 113
Soil 114
Soil Horizons and Classification 114
Residual and Transported Soils 115
Soils, Parent Material, Time, and Slope 115
Organic Activity 117
Soils and Climate 117
Buried Soils 119
Summary 119
Chapter 6
Sediments and Sedimentary Rocks 123
Sediment 124
Transportation 124
Deposition 125
Preservation 126
Lithification 127
Types of Sedimentary Rocks 128
Clastic Rocks 128
Breccia and Conglomerate 128
Sandstone 128
The Fine-Grained Rocks 131
Chemical Sedimentary Rocks 132
Carbonate Rocks 132
Chert 136
Evaporites 136
Organic Sedimentary Rocks 137
Coal 137
The Origin of Oil and Gas 137
Sedimentary Structures 137
Formations 142
Interpretation of Sedimentary Rocks 143
Source Area 143
Environment of Deposition 145
Plate Tectonics and Sedimentary Rocks 147
Summary 148
Chapter 7
Metamorphism, Metamorphic Rocks, and Hydrothermal Rocks 153
Factors Controlling the Characteristics of Metamorphic Rocks 155
Composition of the Parent Rock 155
Temperature 155
Pressure 155
Fluids 158
Time 158
Classification of Metamorphic Rocks 158
Types of Metamorphism 159
Contact Metamorphism 159
Regional Metamorphism 160
Plate Tectonics and Metamorphism 164
Hydrothermal Processes 167
Hydrothermal Activity at Divergent Plate Boundaries 167
Metasomatism 168
Hydrothermal Rocks and Minerals 168
Sources of Water 170
Summary 171
Chapter 8
Time and Geology 175
The Key to the Past 176
Relative Time 176
Principles Used to Determine Relative Age 176
Unconformities 182
Correlation 183
The Standard Geologic Time Scale 187
Numerical Age 189
Isotopic Dating 189
Uses of Isotopic Dating 193
Combining Relative and Numerical Ages 194
Age of the Earth 194
Comprehending Geologic Time 196
Summary 197
Chapter 9
Mass Wasting 201
Classification of Mass Wasting 202
Rate of Movement 202
Type of Material 202
Type of Movement 203
Controlling Factors in Mass Wasting 203
Gravity 206
Water 206
Common Types of Mass Wasting 207
Creep 207
Debris Flow 208
Rockfalls and Rockslides 213
Preventing Landslides 217
Preventing Mass Wasting of Debris 217
Preventing Rockfalls and Rockslides on Highways 217
Summary 219
Chapter 10
Streams and Floods 223
The Hydrologic Cycle 224
Channel Flow and Sheet Flow 224
Drainage Basins 226
Drainage Patterns 227
Factors Affecting Stream Erosion and Deposition 227
Velocity 227
Gradient 228
Channel Shape and Roughness 228
Discharge 229
Stream Erosion 230
Stream Transportation of Sediment 231
Stream Deposition 232
Bars 232
Braided Streams 233
Meandering Streams and Point Bars 237
Flood Plains 237
Deltas 239
Alluvial Fans 242
Flooding 243
Urban Flooding 243
Flash Floods 246
Controlling Floods 246
The Great Flood of 1993 247
Stream Valley Development 249
Downcutting and Base Level 249
The Concept of a Graded Stream 250
Lateral Erosion 251
Headward Erosion and Stream Piracy 251
Stream Terraces 252
Incised Meanders 253
Superposed Streams 255
Summary 255
Chapter 11
Ground Water 259
Porosity and Permeability 260
The Water Table 260
The Movement of Ground Water 262
Aquifers 263
Wells 265
Springs and Streams 267
Ground Water Contamination 268
Balancing Withdrawal and Recharge 272
Effects of Ground-Water Action 273
Caves, Sinkholes, and Karst Topography 273
Other Effects 275
Hot Water Underground 276
Geothermal Energy 278
Summary 279
Chapter 12
Glaciers and Glaciation 283
The Theory of Glacial Ages 284
Glaciers-Where They Are, How They Form and Move 284
Distribution of Glaciers 284
Types of Glaciers 285
Formation and Growth of Glaciers 286
Movement of Valley Glaciers 288
Movement of Ice Sheets 293
Glacial Erosion 294
Erosional Landscapes Associated with Alpine Glaciation 295
Erosional Landscapes Associated with Continental Glaciation 297
Glacial Deposition 299
Moraines 299
Outwash 301
Glacial Lakes and Varves 303
Effects of Past Glaciation 303
The Glacial Ages 304
Direct Effects of Past Glaciation in North America 305
Indirect Effects of Past Glaciation 307
Evidence for Older Glaciation 309
Summary 309
Chapter 13
Deserts and Wind Action 313
Distribution of Deserts 314
Some Characteristics of Deserts 315
Desert Features in the Southwestern United States 318
Wind Action 321
Wind Erosion and Transportation 321
Wind Deposition 324
Summary 331
Chapter 14
Waves, Beaches, and Coasts 335
Water Waves 336
Surf 337
Nearshore Circulation 338
Wave Refraction 338
Longshore Currents 338
Rip Currents 338
Beaches 340
Longshore Drift of Sediment 341
Human Interference with Sand Drift 342
Sources of Sand on Beaches 342
Coasts and Coastal Features 344
Erosional Coasts 344
Depositional Coasts 346
Drowned Coasts 347
Uplifted Coasts 348
Coasts Shaped by Organisms 349
Summary 352
Chapter 15
Geologic Structures 355
Tectonic Forces at Work 356
Stress and Strain in the Earth's Crust 356
Behavior of Rocks to Stress and Strain 357
Present Deformation of the Crust 358
Structures as a Record of the Geologic Past 358
Geologic Maps and Field Methods 359
Folds 361
Geometry of Folds 361
Interpreting Folds 362
Fractures in Rock 365
Joints 365
Faults 366
Summary 375
Chapter 16
Earthquakes 379
Causes of Earthquakes 380
Seismic Waves 383
Body Waves 383
Surface Waves 383
Locating and Measuring Earthquakes 384
Determining the Location of an Earthquake 386
Measuring the Size of an Earthquake 387
Location and Size of Earthquakes in the United States 389
Effects of Earthquakes 392
Tsunamis 395
World Distribution of Earthquakes 398
First-Motion Studies of Earthquakes 400
Earthquakes and Plate Tectonics 402
Earthquakes at Plate Boundaries 402
Subduction Angle 404
Earthquake Prediction 406
Summary 408
Chapter 17
Earth's Interior and Geophysical Properties 413
Evidence from Seismic Waves 414
Earth's Internal Structure 416
The Crust 417
The Mantle 418
The Core 421
Isostasy 424
Gravity Measurements 426
Earth's Magnetic Field 428
Magnetic Reversals 429
Magnetic Anomalies 432
Heat Within the Earth 433
Geothermal Gradient 433
Heat Flow 434
Summary 435
Chapter 18
The Sea Floor 439
Methods of Studying the Sea Floor 440
Features of the Sea Floor 443
Continental Shelves and Continental Slopes 443
Submarine Canyons 444
Turbidity Currents 445
Passive Continental Margins 446
The Continental Rise 446
Abyssal Plains 447
Active Continental Margins 447
Oceanic Trenches 447
The Mid-Oceanic Ridge 448
Geologic Activity on the Ridge 448
Biologic Activity on the Ridge 450
Fracture Zones 450
Seamounts, Guyots, and Aseismic Ridges 450
Reefs 452
Sediments of the Sea Floor 454
Oceanic Crust and Ophiolites 455
The Age of the Sea Floor 457
The Sea Floor and Plate Tectonics 457
Summary 457
Chapter 19
Plate Tectonics 461
The Early Case for Continental Drift 462
Skepticism about Continental Drift 465
Paleomagnetism and the Revival of Continental Drift 466
Recent Evidence for Continental Drift 467
History of Continental Positions 468
Sea-Floor Spreading 468
Hess's Driving Force 468
Explanations 468
Plates and Plate Motion 470
How Do We Know That Plates Move? 471
Marine Magnetic Anomalies 471
Another Test: Fracture Zones and Transform Faults 474
Measuring Plate Motion Directly 474
Divergent Plate Boundaries 474
Transform Boundaries 477
Convergent Plate Boundaries 479
Ocean-Ocean Convergence 479
Ocean-Continent Convergence 480
Continent-Continent Convergence 482
Backarc Spreading 483
The Motion of Plate Boundaries 484
Plate Size 484
The Attractiveness of Plate Tectonics 485
What Causes Plate Motions? 486
Mantle Plumes and Hot Spots 488
The Relationship Between Plate Tectonics and Ore Deposits 490
A Final Note 492
Summary 492
Chapter 20
Mountain Belts and the Continental Crust 497
Characteristics of Major Mountain Belts 499
Size and Alignment 499
Ages of Mountain Belts and Continents 500
Thickness and Characteristics of Rock Layers 501
Patterns of Folding and Faulting 502
Metamorphism and Plutonism 504
Normal Faulting 504
Thickness and Density of Rocks 504
Features of Active Mountain Ranges 505
The Evolution of a Mountain Belt 505
The Accumulation Stage 505
The Orogenic Stage 506
The Uplift and Block-faulting Stage 509
The Growth of Continents 514
Displaced Terranes 514
Summary 516
Chapter 21
Geologic Resources 519
Types of Resources 520
Resources and Reserves 521
Energy Use 521
Oil and Natural Gas 522
The Occurrence of Oil and Gas 522
Recovering the Oil 523
How Much Oil Do We Have Left? 524
Heavy Crude and Oil Sands 525
Oil Shale 525
Coal 526
Varieties of Coal 527
Occurrence of Coal 527
Environmental Effects 528
Reserves and Resources 529
Uranium 529
Alternative Sources of Energy 529
Metals and Ores 530
Origin of Metallic Ore Deposits 530
Ores Associated with Igneous Rocks 530
Ores Formed by Surface Processes 531
Metal Ores and Plate Tectonics 533
Mining 533
Environmental Effects 533
Some Important Metals 535
Iron 535
Copper 535
Aluminum 536
Lead 536
Zinc 536
Silver 536
Gold 536
Other Metals 537
Nonmetallic Resources 537
Construction Materials 537
Fertilizers and Evaporites 537
Other Nonmetallics 538
Some Future Trends 538
Summary 540
Appendixes A-G 542
Glossary 553
Index 567




Library of Congress Subject Headings for this publication: Physical geology