Download Essentials of Geology

SIXTH EDITION
Essentials
of Geology
Frederick K. Lutgens
Edward J. Tarbuck
Illinois Central College
Illustrated by
Dennis Tasa
Prentice Hall
Upper Saddle River, New Jersey 07458
Contents
Preface
xi
1
An Introduction to Geology
The Science of Geology 2
Historical Notes about Geology 2
Catastrophism 3
The Birth of Modern Geology 3
Geologic Time 4
The Nature of Scientific Inquiry 5
Collecting Facts 6
Hypothesis 6
Theory 6
Scientific Methods 8
A View of Earth 8
Hydrosphere 9
Atmosphere 9
Lithosphere .9
Biosphere 10
Dynamic Earth 11
Plate Tectonics 11 _- •
Plate Boundaries 12
Divergent Boundaries 12
Convergent Boundaries 13
Transform Fault Boundaries 13
Earth as a System: The Rock Cycle 14
The Basic Cycle 14
Alternative Paths 17
The Rock Cycle and Plate Tectonics 18
Crystal Form 29
Luster 30
Color 30
Streak 30
Hardness 30
Cleavage 30
Fracture 31
Specific Gravity 31
Other Properties of Minerals 31
Mineral Groups 32
Silicate Structures 32
Common Silicate Minerals 34
Important Nonsilicate Minerals 37
Mineral Resources 38
Igneous Rocks 44
Crystallization of Magma 45
Igneous Rock Textures 47
Igneous Rock Composition 49
Bowen's Reaction Series 49
Magmatic Differentiation 50
Assimilation and Magma Mixing 51
Naming Igneous Rocks 51
Granitic Rocks 53
Andesitic Rocks 56
Basaltic Rocks 56
Pyroclastic Rocks 56
Mineral Resources and Igneous Processes
57
Minerals: Building Blocks
of Rocks 23
Volcanoes and Other
Igneous Activity 65
Minerals Versus Rocks 24
Composition and Structure of Minerals
Atomic Structure 25
How Atoms Bond Together 26
Covalent Bonds 28
Isotopes and Radioactivity 28
Properties of Minerals 29
Anatomy of an Eruption 66
Not All Volcanoes are Alike 68
The Nature of Volcanic Eruptions 68
Factors Affecting Viscosity 68
Importance of Dissolved Gases in Magma
What is Extruded During Eruptions? 70
Lava Flows 70
vi
25
70
Contents vii
Gases 71
Pyroclastics 71
Volcano Types 72
Shield Volcanoes 72
Cinder Cones 73
Composite Cones 74
Nuee Ardente 75
Lahar 75
Volcanic Landforms 78
Volcanic Pipes and Necks 78
Craters and Calderas 78
Fissure Eruptions and Lava Plateaus 80
Pyroclastic Flows 80
Volcanoes and Climate 80
Intrusive Igneous Activity 82
Intrusive Igneous Bodies 83
Igneous Activity and Plate Tectonics 83
Origin of Magma 83
Distribution of Igneous Activity 86
Weathering and Soils
93
Earth's External Processes 94
Weathering 94
Mechanical Weathering 94
Frost Wedging 96
Unloading 96
Thermal Expansion 97
Biological Activity 97
Chemical Weathering' '98
Water and Carbonic Acid 98
How Granite Weathers 98
Weathering of Silicate Minerals 98
Spheroidal Weathering 99
Rates of Weathering 99
Mineral Makeup 99
< Climate 100
Soil 100
An Interface in the Earth System 101.
What Is Soil? 101
Controls of Soil Formation 102
Parent Material 102
Time 103
Climate 103
Plants and Animals 103
Slope 104
The Soil Profile 104
Soil Types 106
Pedalfer 106
Pedocal 106
Laterite 106
Soil Erosion 108
How Soil Is Eroded 108
Rates of Erosion 108
Sedimentation and Chemical Pollution
Weathering Creates Ore Deposits 109
Bauxite 110
Other Deposits 110
Sedimentary Rocks
109
114
Types of Sedimentary Rocks 115
Detrital Sedimentary Rocks 115
Shale 116
Sandstone 117
Conglomerate and Breccia 119
Chemical Sedimentary Rocks 120
Limestone 120
Dolostone 122
Chert 122
Evaporites 123
Coal 123
Turning Sediment into Sedimentary Rock 124
Classification of Sedimentary Rocks 124
Sedimentary Structures 126
Nonmetallic Mineral Resources From
Sedimentary Rocks 129
Energy Resources From Sedimentary Rocks 130
Coal 131
Oil and Natural Gas 132
7
Metamorphic Rocks
13 7
Metamorphism 138
Where Does Metamorphism Occur? 138
Agents of Metamorphism 139
Heat as a Metamorphic Agent 139
Pressure as a Metamorphic Agent 140
Chemical Activity as a Metamorphic Agent 140
How Metamorphism Alters Rocks 141
Textural Changes 141
Mineralogical Changes 142
Common Metamorphic Rocks 143
Foliated Rocks 143
Nonfoliated Rocks 145
Environments That Metamorphose Rocks 146
Contact Metamorphism 146
Regional Metamorphism 147
Metamorphism Along Fault Zones 150
Metamorphism and Mineral Resources 150
v i i i Contents
8
Mass Wasting
155
Mass Wasting and Landform Development 156
Controls and Triggers of Mass Wasting 156
The Role of Water 156
Oversteepened Slopes 156
Vegetation 156
• Earthquakes as Triggers 158
Classification of Mass-Wasting Processes 158
Type of Material 158
Type of Motion 158
Rate of Movement 160
Slump 160
Rockslide 161
Mudflow 161
Mudflows in Semiarid Regions 162
Lahars 163
Earthflow 163
Slow Movements 164
Creep 164
Solifluction 164
Running Water
169
Earth as a System: The Hydrologic Cycle
Running Water 171
Streamflow 172
Changes Downstream- 173
Base Level and Graded Streams 175
Work of Streams 176
Erosion 176
Transportation 177
Deposition 178
Stream Valleys 180
Narrow Valleys 180
Wide Valleys 182
Drainage Basins and Patterns 183
Stages of Valley Development 184
170
10
Groundwater
191
Importance of Underground Water 192
Distribution of Underground Water 192
The Water Table 193
How Groundwater Moves 195
Porosity 196
Permeability, Aquitards and Aquifers 196
Springs 196
Wells 197
Artesian Wells 198
Environmental Problems of Groundwater 199
Groundwater as a Nonrenewable Resource 199
Land Subsidence Caused by Groundwater
Withdrawal 199
Groundwater Contamination 200
Hot Springs and Geysers 201
Geothermal Energy 203
The Geologic Work of Groundwater 204
Caverns 204
Karst Topography 205
11
Glaciers and Glaciation
210
Glaciers: A Part of the Hydrologic Cycle 211
How Glaciers Move 212
Rates of Glacial Movement 212
Budget of a Glacier 214
Glacial Erosion 215
Landforms Created by Glacial Erosion 216
Glaciated Valleys 216
Aretes and Horns 217
Roches Moutonnees 218
Glacial Deposits 218
Types of Glacial Drift 218
Moraines, Outwash Plains, and Kettles 220
Drumlins, Eskers, and Kames 222
Glaciers of the Past 223
Some Indirect Effects of Ice Age Glaciers 223
Causes of Glaciation 225
Plate Tectonics 225
Variations in Earth's Orbit 226
12
Deserts and Wind
232
Common Misconceptions 233
Distribution and Causes of Dry Lands 234
Low-Latitude Deserts 234
Middle-Latitude Deserts 234
Geologic Processes In Arid Climates 234
Weathering 235
The Role of Water 236
Transportation of Sediment by Wind 237
Bed Load 237
Suspended Load 238
Wind Erosion 238
Contents
Deflation, Blowouts, and Desert Pavement
Wind Abrasion 240
Wind Deposits 240
Sand Deposits 240
Types of Sand Dunes 241
Loess Deposits 243
Basin and Range: The Evolution of a Desert
Landscape 244
239
15
Earthquakes
and Earth's Interior
249
Waves 250
How Waves Form 251
How Waves Move 251
Wave Erosion 252
Wave Refraction 253
Moving Sand Along the Beach 254
Shoreline Features 255
Wave-Cut Cliffs and Platforms 255
Arches, Stacks, Spits, and Bars 255
Barrier Islands 256
The Evolving Shore 257
Shoreline Erosion Problems 257
Groins 258
Breakwaters and Seawalls 259
Beach Nourishment 260
Contrasting the Atlantic and Pacific Coasts
Emergent and Submergent Coasts 261
Tides 261
Causes of Tides 263
Spring and Neap Tides 265
260
269
The Vast World Ocean 270
Earth Beneath the Sea 271
Continental Margins 272
Continental Shelf 272
Continental Slope and Rise 273
Submarine Canyons and Turbidity Currents
The Ocean Basin Floor 276
Deep-Ocean Trenches 277
Abyssal Plains 277
Seamounts 279
Mid-Ocean Ridges 279
Coral Reefs and Atolls 280
Seafloor Sediments 281
Terrigenous Sediment 282
16
Plate Tectonics
14
the Ocean Floor
287
What Is an Earthquake? 289
Earthquakes and Faults 289
Elastic Rebound 291
Foreshocks and Aftershocks 292
Tectonic Forces and Earthquakes 293
Earthquake Waves 293
Finding Earthquake Epicenters 296
Earthquake Intensity and Magnitude 298
Destruction from Earthquakes 299
Destruction from Seismic Vibrations 300
Tsunami 301
Landslides and Ground Subsidence 302
Fire 303
Can Earthquakes Be Predicted? 303
Short-Range-Predictions 304
Long-Range Predictions 304
Earthquakes Reveal Earth's Interior 306
Discovering Earth's Structure 306
Discovering Earth's Composition 307
13
Shorelines
Biogenous Sediment 282
Hydrogenous Sediment 283
273
313
Continental Drift: An Idea Before Its Time 315
Evidence: The Continental Jigsaw Puzzle 315
Evidence: Fossils Match Across the Seas 315
Evidence: Rock Types and Structures
Match 317
Evidence: Ancient Climates 317
The Great Debate 318
Plate Tectonics: A Modern Version of an
Old Idea 319
Plate Boundaries 322
Divergent Boundaries 322
Convergent Boundaries 326
Transform Boundaries 329
Testing the Plate Tectonics Model 330
Evidence: Paleomagnetism 330
Evidence: Earthquake Patterns 334
Evidence: Ocean Drilling 334
Evidence: Hot Spots 335
Pangaea: Before and After 336
Breakup of Pangaea 336
ix
X
Contents
19
Before Pangaea 337
The Driving Mechanism 339
Convection Current Hypothesis 339
Slab-Push and Slab-Pull Hypotheses 340
Hot Plumes Hypothesis 340
Earth History:
A Brief Summary
17
Mountain Building
345
Crustal Uplift 346
Isostasy 347
Isostatic Adjustment 347
Rock Deformation 348
Folds 349
Faults and Joints 350
Mountain Types 353
Fault-Block Mountains 354
Upwarped Mountains 356
Folded Mountains 356
Mountain Building 356
Mountain Building at Convergent Boundaries
Mountain Building and Continental Accretion
393
Origin of Earth 394
Earth's Atmosphere Evolves 396
Precambrian Time: Vast and Enigmatic 396
Precambrian Rocks 397
Precambrian Fossils 398
Paleozoic Era: Life Explodes 398
Early Paleozoic History 401
Early Paleozoic Life 401
Late Paleozoic History 402
Late Paleozoic Life 403
Mesozoic Era: Age of the Dinosaurs 405
Mesozoic History 405
Mesozoic Life 407
Cenozoic Era: Age of Mammals 409
Cenozoic North America 410
Cenozoic Life 412
358
362
Appendix A
Metric and English Units Compared
18
Geologic Time
369
Relative Dating— Key Principles 370
Law of Superposition 371
Principle of Original Horizontality 371
Principle of Cross-Cutting Relationships 371
Inclusions 373
Unconformities 373
Using Relative Dating Principles 374
Correlation of Rock Layers 375
Fossils: Evidence of Past Life 375
Types of Fossils 375
Conditions Favoring Preservation 379
Fossils and Correlation 379
Absolute Dating with Radioactivity 380
Radioactivity 380
Half-Life 382
Radiometric Dating 382
Carbon-14 Dating 384
Importance of Radiometric Dating 385
The Geologic Time Scale 385
Difficulties in Dating the Geologic Time Scale 387
Appendix B
Periodic Table of the Elements
Appendix C
Mineral Identification Key
Appendix D
Topographic Maps
Glossary
434
Index 446
427
424
423
421