Physical Geology Earth Revealed

670 Pages·2010·99.819 MB·English

by  Diane Carlson

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Generalized Geologic and Tectonic Map of North America
SEDIMENTARY UNITS SPECIAL UNITS PRECAMBRIAN
Thick deposits in structurally Paleozoic and Mesozoic Former subduction complex Exposed parts of Basement igneous and
negative areas active margin deposits rocks of the Pacific border Ouachita foldbelt metamorphic complexes
mainly of Precambrian age
Synorogenic and Paleozoic and Mesozoic
postorogenic deposits passive margin deposits Proboaf bIlnen wuietisatenr nfo eldxbteenltsion Grenville foldbelt
In cores of northern Deformed 880–1,000 m.y. ago
Alaska ranges
Late Precambrian deposits
PLATFORM AREAS
Of Middle and Upper
Proterozoic ages Hudsonian foldbelts
Deformed 1,640–1,820 m.y. ago
VOLCANIC AND PLUTONIC UNITS
Ice cap of Quaternary age Platform deposits on
On Precambrian and Precambrian basement
Paleozoic basement In central craton
Kenoran foldbelts
Postorogenic volcanic cover Ultramafic rocks Deformed 2,390–2,600 m.y. ago
Platform deposits on Platform deposits within
Paleozoic basement the Precambrian
Granitic plutons In Atlantic and Mainly in the Anorthosite bodies
Ages are generally within the Gulf coastal plains Canadian Shield Plutons composed almost
span of the tectonic cycle of entirely of plagioclase
the foldbelt in which they lie
STRUCTURAL SYMBOLS
Normal fault Subsea fault
Hachures on downthrown side
Salt domes and salt diapirs
In Gulf coastal plain
Strike-slip fault and Gulf of Mexico
Arrows show relative
lateral movement
Volcano
Thrust fault World’s oldest rock
Barbs on upthrown side
1000
0
+1000
Contours on basement surfaces
beneath platform areas
Axes of seafloor spreading All contours are below sea level
except where marked with plus
symbols. Interval is 1,000 meters
Modified from the Generalized Tectonic Map of North America by P.B.
King and Gertrude J. Edmonston, U.S. Geological Survey Map I-688
Metamorphic Shale Conglomerate
Granite
basement rock
Basalt Limestone Sandstone Breccia
Crystalline Cross-bedded
continental Dolomite sandstone Rock salt
crust
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Ninth Edition
Diane H. Carlson
California State University at Sacramento
Charles C. Plummer
Emeritus of California State University at Sacramento
Lisa Hammersley
California State University at Sacramento
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TM
PHYSICAL GEOLOGY: EARTH REVEALED, NINTH EDITION
Published by McGraw-Hill, a business unit of The McGraw-Hill Companies, Inc., 1221 Avenue of the Americas,
New York, NY 10020. Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved. Previous
editions © 2009, 2008, and 2006. No part of this publication may be reproduced or distributed in any form or
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Companies, Inc., including, but not limited to, in any network or other electronic storage or transmission, tor
broadcast for distance learning.
Some ancillaries, including electronic and print components, may not be available to customers outside the
United States.
This book is printed on acid-free paper.
1 2 3 4 5 6 7 8 9 0 DOW/DOW 1 0 9 8 7 6 5 4 3 2 1 0
ISBN 978-0-07-336940-2
MHID 0-07-336940-3
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All credits appearing on page or at the end of the book are considered to be an extension of the copyright page.
Library of Congress Cataloging-in-Publication Data
Carlson, Diane H.
Physical geology: earth revealed.—9th ed. / Diane H. Carlson, Charles C. Plummer, Lisa Hammersley.
p. cm.
McGeary’s name appears first on the earlier eds.
Companion text to Earth revealed, a PBS television course and video resource.
Includes bibliographical references and index.
ISBN-13: 978-0-07-336940-2 (softcover : alk. paper)
ISBN-10: 0-07-336940-3 (softcover : alk. paper)
I. Plummer, Charles C., 1937- II. Hammersley, Lisa. III. Plummer, Charles C., 1937- IV. Hammersley,
Lisa. V. Earth revealed (Television program) VI. Title. VII. Title: Earth revealed.
QE28.2.M34 2010
550—dc22
2009040823
The Internet addresses listed in the text were accurate at the time of publication. The inclusion of a Web site does
not indicate an endorsement by the authors or McGraw-Hill, and McGraw-Hill does not guarantee the accuracy
of the information presented at these sites.
www.mhhe.com
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Chapter 1
Introducing Geology, the Essentials of Plate Tectonics,
and Other Important Concepts 3
Chapter 2
Earth’s Interior and Geophysical Properties 29
Chapter 3
The Sea Floor 53
Chapter 4
Plate Tectonics 75
Chapter 5
Mountain Belts and the Continental Crust 111
Chapter 6
Geologic Structures 135
Chapter 7
Earthquakes 157
Chapter 8
Time and Geology 189
Chapter 9
Atoms, Elements, and Minerals 217
Chapter 10
Volcanism and Extrusive Rocks 243
Chapter 11
Igneous Rocks, Intrusive Activity, and the Origin of Igneous Rocks 275
Chapter 12
Weathering and Soil 301
Chapter 13
Mass Wasting 325
Chapter 14
Sediment and Sedimentary Rocks 351
Chapter 15
Metamorphism, Metamorphic Rocks, and Hydrothermal Rocks 383
Chapter 16
Streams and Floods 407
Chapter 17
Ground Water 443
Chapter 18
Deserts and Wind Action 467
Chapter 19
Glaciers and Glaciation 489
Chapter 20
Waves, Beaches, and Coasts 521
Chapter 21
Resources 543
Chapter 22
The Earth’s Companions 573
v
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Preface xiii Earth’s Internal Structure 32
The Crust 32
The Mantle 33
The Core 35
Isostasy 38
Gravity Measurements 40
Earth’s Magnetic Field 41
Magnetic Reversals 43
Magnetic Anomalies 44
1 Heat within the Earth 46
Geothermal Gradient 46
Introducing Geology, the Essentials
Heat Flow 47
of Plate Tectonics, and Other SUMMARY 49
Important Concepts 3
Who Needs Geology? 4
Supplying Things We Need 4
Protecting the Environment 5
Avoiding Geologic Hazards 5
Understanding Our Surroundings 11
Earth Systems 11
An Overview of Physical Geology—Important Concepts 13 3
Internal Processes: How the Earth’s Internal Heat Engine
Works 13 The Sea Floor 53
Earth’s Interior 14
The Theory of Plate Tectonics 15
Origin of the Ocean 54
Divergent Boundaries 15
Convergent Boundaries 18 Methods of Studying the Sea Floor 54
Transform Boundaries 20
Features of the Sea Floor 56
Surficial Processes: The Earth’s External Heat Engine 20
Continental Shelves and Continental Slopes 56
Geologic Time 25
Submarine Canyons 58
SUMMARY 26
Turbidity Currents 59
Passive Continental Margins 60
The Continental Rise 61
Abyssal Plains 61
Active Continental Margins 62
Oceanic Trenches 62
Mid-Oceanic Ridges 63
Geologic Activity at the Ridges 63
Biologic Activity at the Ridges 64
Fracture Zones 64
Seamounts, Guyots, and Aseismic Ridges 65
2
Reefs 66
Earth’s Interior and Geophysical Sediments of the Sea Floor 68
Properties 29 Oceanic Crust and Ophiolites 68
The Age of the Sea Floor 71
The Sea Floor and Plate Tectonics 71
Introduction 30
Evidence from Seismic Waves 30 SUMMARY 71
vi
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CONTENTS vii
Thickness and Characteristics of Rock Layers 116
Patterns of Folding and Faulting 117
Metamorphism and Plutonism 117
Normal Faulting 118
Thickness and Density of Rocks 119
Features of Active Mountain Ranges 120
Evolution of Mountain Belts 120
Orogenies and Plate Convergence 120
4
Post-Orogenic Uplift and Block-Faulting 126
Plate Tectonics 75 The Growth of Continents 129
Displaced Terranes 130
The Early Case for Continental Drift 77 SUMMARY 131
Skepticism about Continental Drift 79
Paleomagnetism and the Revival of Continental Drift 80
Recent Evidence for Continental Drift 81
History of Continental Positions 82
Seafloor Spreading 82
Hess’s Driving Force 82
Explanations 83
Plates and Plate Motion 84
How Do We Know that Plates Move? 84
6
Marine Magnetic Anomalies 84
Another Test: Fracture Zones and Transform Faults 87
Geologic Structures 135
Measuring Plate Motion Directly 88
Divergent Plate Boundaries 88
Transform Boundaries 93 Tectonic Forces at Work 136
Stress and Strain in the Earth’s Lithosphere 136
Convergent Plate Boundaries 93
How Do Rocks Behave When Stressed? 137
Ocean-Ocean Convergence 93
Structures as a Record of the Geologic Past 138
Ocean-Continent Convergence 95
Continent-Continent Convergence 95 Geologic Maps and Field Methods 138
The Motion of Plate Boundaries 96 Folds 140
Geometry of Folds 141
Plate Size 99
Further Description of Folds 143
The Attractiveness of Plate Tectonics 99
Fractures in Rock 145
What Causes Plate Motions? 100
Joints 145
Mantle Convection 100 Faults 147
Ridge Push 101 SUMMARY 154
Slab Pull 101
Trench Suction 101
Mantle Plumes and Hot Spots 101
A Final Note 102
SUMMARY 106
7
Earthquakes 157
Causes of Earthquakes 158
5
Seismic Waves 159
Mountain Belts and the Continental
Body Waves 159
Surface Waves 160
Crust 111
Locating and Measuring Earthquakes 161
Determining the Location of an Earthquake 161
Introduction 112 Measuring the Size of an Earthquake 163
Characteristics of Major Mountain Belts 115 Location and Size of Earthquakes in the United States 165
Size and Alignment 115 Effects of Earthquakes 167
Ages of Mountain Belts and Continents 115 Tsunami 171
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viii CONTENTS
World Distribution of Earthquakes 174 Cleavage 234
Fracture 236
First-Motion Studies of Earthquakes 177
Specific Gravity 236
Earthquakes and Plate Tectonics 177 Special Properties 236
Earthquakes at Plate Boundaries 178 Chemical Tests 237
Subduction Angle 179 The Many Conditions of Mineral Formation 239
Earthquake Prediction and Seismic Risk 179
SUMMARY 239
SUMMARY 185
10
8
Volcanism and Extrusive Rocks 243
Time and Geology 189
Relationships to Earth Systems 244
The Key to the Past 190
Pyroclastic Debris and Lava Flows 244
Relative Time 191
Living with Volcanoes 244
Principles Used to Determine Relative Age 191
Unconformities 196 Supernatural Beliefs 244
Correlation 198 The Growth of an Island 247
The Standard Geologic Time Scale 201 Geothermal Energy 247
Numerical Age 201 Effect on Climate 247
Volcanic Catastrophes 247
Isotopic Dating 202
Eruptive Violence and Physical Characteristics of Lava 250
Uses of Isotopic Dating 207
Extrusive Rocks and Gases 252
Combining Relative and Numerical Ages 208
Scientific Investigation of Volcanism 252
Age of the Earth 209
Gases 252
Comprehending Geologic Time 210
Extrusive Rocks 253
SUMMARY 212
Composition 253
Extrusive Textures 254
Types of Volcanoes 257
Shield Volcanoes 258
Cinder Cones 258
Composite Volcanoes 260
Volcanic Domes 263
Lava Floods 263
Submarine Eruptions 268
Pillow Basalts 268
9
SUMMARY 270
Atoms, Elements, and Minerals 217
Relationships to Earth Systems 218
Minerals 218
Introduction 218
Minerals and Rocks 219
Atoms and Elements 220
Ions and Bonding 222
Crystalline Structures 223
The Silicon-Oxygen Tetrahedron 224 11
Nonsilicate Minerals 229
Igneous Rocks, Intrusive Activity,
Variations in Mineral Structures and Compositions 229
The Physical Properties of Minerals 229 and the Origin of Igneous Rocks 275
Color 230
Streak 230
Relationships to Earth Systems 276
Luster 231
Hardness 231 The Rock Cycle 276
External Crystal Form 232 A Plate Tectonic Example 277
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CONTENTS ix
Igneous Rocks 278 Soil Erosion 318
Igneous Rock Textures 279 Soil Classification 319
Identification of Igneous Rocks 279 SUMMARY 321
Chemistry of Igneous Rocks 283
Intrusive Bodies 284
Shallow Intrusive Structures 284
Intrusives That Crystallize at Depth 286
Abundance and Distribution of Plutonic Rocks 287
How Magma Forms 288
Heat for Melting Rock 288
The Geothermal Gradient and Partial Melting 288
Decompression Melting 288
Addition of Water 289 13
How Magmas of Different Compositions Evolve 289
Sequence of Crystallization and Melting 289 Mass Wasting 325
Differentiation 290
Partial Melting 292
Assimilation 292 Surficial Processes 325
Mixing of Magmas 292 Relationships to Earth Systems 326
Explaining Igneous Activity by Plate Tectonics 293
Introduction to Mass Wasting 326
Igneous Processes at Divergent Boundaries 293
Classification of Mass Wasting 327
Intraplate Igneous Activity 294
Rate of Movement 327
Igneous Processes at Convergent Boundaries 295
Type of Material 327
SUMMARY 297
Type of Movement 327
Controlling Factors in Mass Wasting 330
Gravity 330
Water 331
Triggers 332
Common Types of Mass Wasting 332
Creep 332
Flow 334
Rockfalls and Rockslides 338
Underwater Landslides 341
Preventing Landslides 346
Preventing Mass Wasting of Soil 346
12 Preventing Rockfalls and Rockslides on Highways 347
SUMMARY 348
Weathering and Soil 301
Weathering, Erosion, and Transportation 302
Weathering and Earth Systems 302
Atmosphere 302
Hydrosphere 302
Biosphere 303
How Weathering Changes Rocks 303
Effects of Weathering 304 14
Mechanical Weathering 304
Sediment and Sedimentary Rocks 351
Pressure Release 305
Frost Action 305
Other Processes 306
Relationship to Earth Systems 352
Chemical Weathering 306
Sediment 352
Role of Oxygen 307
Transportation 353
Role of Acids 308
Deposition 354
Solution Weathering 309
Preservation 355
Chemical Weathering of Feldspar 310
Lithification 355
Chemical Weathering of Other Minerals 311
Weathering Products 311 Types of Sedimentary Rocks 356
Factors Affecting Weathering 312 Detrital Rocks 356
Soil 312 Breccia and Conglomerate 356
Soil Horizons 313 Sandstone 357
Factors Affecting Soil Formation 315 The Fine-Grained Rocks 357
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