Preface   xvii

CHAPTER 1

Earth as a System   1

Exploring the Earth System   2

The Components of the System   2

The Fragility of the System   2

The Principle of Uniformitarianism   3

Actualism: The Present as the Key to the Past   3

The End of Catastrophism   4

The Nature and Origin of Rocks   5

Basic Kinds of Rocks   5

Classification of Bodies of Rock   8

Steno's Three Laws for Sedimentary Rocks   9

The Rock Cycle   9

Global Dating of the Rock Record   11

Fossils, Markers, and the Relative Ages of Rocks   11

Radioactivity and the Actual Ages of Rocks   12

The Geologic Time Scale   13

Development of the Time Scale   14

Imaging the Earth Below   14

The Density Gradient   15

Lithosphere and Asthenosphere   16

Plate Tectonics   17

Plate Movements   17

The Engine of Plate Tectonics   19

Plate Tectonics and the Rock Cycle   19

The Water Cycle   20

The Reservoirs   21

Interactions with the Rock Cycle   22

Directional Change in Earth's History   22

The Evolution of Life   22

Physical and Chemical Trends   23

The History of Ecosystems   24

Episodic Change in Earth's History   24

Gaps in the Stratigraphic Record   24

Catastrophic Deposition   25

Episodic Events in the History of Life   25

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CHAPTER 2

Rock-Forming Minerals and Rocks   29

The Structure of Minerals   29

Atoms, Elements, and Isotopes   29

Visual Overview: Rocks and Their Origins   30

Chemical Reactions   33

Crystal Lattices   35

Ion Substitution   36

The Properties of Minerals   37

Hardness   37

Density   38

Fracture Patterns   38

The Origins of Minerals   38

Tracing the Origins of Rocks   38

Families of Rock-Forming Minerals   38

Types of Rock   40

Igneous Rocks   40

Sediments and Sedimentary Rocks   42

For the Record 2-1: Why Our Buildings Are Made from Fossils   48

Metamorphic Rocks   51

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CHAPTER 3

The Diversity of Life   57

Fossils   60

Hard Parts: Commonly Preserved   

Skeletal Features of Animals   60

Preservation of Soft Parts of Animals   60

Permineralization   61

Molds and Impressions   61

Trace Fossils   62

Fossil Fuels   62

The Quality of the Fossil Record   63

Kingdoms of Organisms   63

Taxonomic Groups   64

Reconstructing the Tree of Life   64

Identifying Clades and Their Relationships   66

A General Cladogram for Vertebrates   66

A General Phylogeny for Vertebrates   67

Analyses at Lower Taxonomic Levels for Horses   69

The Quality of Phylogenetic Reconstructions   70

Prokaryotes: The Two Kingdoms of Bacteria   70

Archaeobacteria   70

Eubacteria   70

The Protist and Fungus Kingdoms   71

Protists   71

Fungi   74

The Plant Kingdom   74

Seedless Vascular Plants   75

Seed Plants   75

The Animal Kingdom   76

Sponges:Simple Invertebrates   76

Cnidarians   77

Chordates   82

For The Record 3-1: Bringing Some Very Old Vertebrates to Light   86

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CHAPTER 4

Environments and Life   91

The Principles of Ecology   94

A Species' Position in Its Environment   94

Communities of Organisms   95

Biogeography   97

The Atmosphere   98

The Chemical Composition of the Atmosphere   98

Temperatures and Circulation in the Atmosphere   99

The Terrestrial Realm   101

Latitudinal Zones and Vegetation   101

The Effects of Altitude on Climate   105

Land, Water, and Seasonal Temperature Change   106

Fossil Plants as Indicators of Climate   108

The Marine Realm   109

Water Movements   109

The Depth of the Sea   111

Marine Life Habits and Food Webs   112

Marine Temperature and Biogeography   114

Salinity as a Limiting Factor   115

For The Record 4-1: The Fragile Reef   116

Freshwater Environments   117

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CHAPTER 5

Sedimentary Environments   121

Soil Environments      124

How Soils Form   124

Ancient Soils   125

The Depositional Environments of Freshwater Lakes and Glaciers   126

Freshwater Lake Environments   126

Glacial Environments   126

Deserts and Arid Basins   128

Death Valley: A Modern Example   129

Sand Dunes   130

River Systems as Depositional Environments   131

Alluvial Fans and Braided-Stream Deposits in Moist Climates   131

Meandering Rivers   132

Deltas   134

Marine Depositional Environments   138

The Barrier Island-Lagoon Complex   138

Open Shelf Deposits   139

Fossils as Marine Environmental Indicators   140

Reefs   140

Carbonate Platforms   143

Deep-Sea Sediments   145

Submarine Slopes and Turbidites   145

Pelagic Sediments   147

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CHAPTER 6

Correlation and Dating of the Rock Record   151

The Geologic Time Scale   151

Visual Overview: Methods of Stratigraphic Correlation   152

The Fossil Succession   154

Geologic Systems   155

Stratigraphic Units   156

Time-Rock Units and Time Units   156

Biostratigraphic Units   157

Magnetic Stratigraphy and Polarity Time-Rock Units   158

Rock Units, Stratigraphic Sections, and Facies   161

Early Estimates of Earth's Absolute Age   163

Salts in the Ocean   163

Rates of Accumulation of Sediment   163

Earth's Temperature   164

Radioactivity and Absolute Ages   164

Radiometric Dating   164

Useful Isotopes   165

Radioactivity vs. Fossils: The Accuracy of Correlation   167

Dating by Other Stratigraphic Features   169

Isotope Stratigraphy   169

Event Stratigraphy   169

Unconformities, Bedding Surfaces, and Seismic Stratigraphy   172

Sequences   173

For The Record 6-1: Searching for Oil Off Southern New Jersey   176

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CHAPTER 7

Evolution and the Fossil Record   181

Charles Darwin's Contribution   185

The Voyage of the Beagle   185

Anatomical Evidence   188

Natural Selection   188

Genes, DNA, and Chromosomes   189

Populations, Species, and Speciation   190

Extinction   190

Rates of Origination and Extinction of Taxa   191

Evolutionary Radiation   191

Rates of Extinction   194

For The Record 7-1: The Coming Mass Extinction   194

Evolutionary Convergence   198

Evolutionary Trends   198

Change of Body Size   198

The Structure of Evolutionary Trends   200

The Irreversibility of Evolution   204

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CHAPTER 8

The Theory of Plate Tectonics   207

The History of Opinion about Continental Drift   207

A Twentieth-Century Pioneer: Alfred Wegener   211

Alexander Du Toit and the Gondwanaland Sequence   212

The Rejection of Continental Drift   214

The Puzzle of Paleomagnetism   215

The Rise of Plate Tectonics      216

Seafloor Spreading   217

The Triumph of Paleomagnetism   219

Faulting and Volcanism along Plate Boundaries   220

Kinds of Faults   220

What Happens at Ridges   221

Transform Faults   222

Subduction at Deep-Sea Trenches   223

Why Plates Move   226

Where Slabs Go   226

Relative Plate Movements   226

Absolute Plate Movements   227

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CHAPTER 9

Continental Tectonics and Mountain Chains   231

The Rifting of Continents   234

Three-Armed Rifts and Hot Spots   234

Geologic Features of Continental Rift Valleys   235

Passive Margins of Continents   236

Bending and Flowing of Rocks   237

Folding   237

The Terminology of Folds   238

Mountain Building   240

Orogenesis by Continental Collision   240

Orogenesis without Continental Collision   241

Mechanisms of Deformation   242

Foreland Basin Deposition   243

The Andes: Mountain Building without Continental Collision   244

For The Record 9-1: Where Earth Shakes   246

The Himalayas   248

Plate Movements   248

The Pattern of Orogenesis   249

Suturing of Small Landmasses to Continents   251

Tectonics of Continental Interiors   252

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CHAPTER 10

Major Chemical Cycles   257

Reservoirs   257

Fluxes   259

Feedback   259

Carbon Dioxide, Oxygen, and Biological Processes   261

The Photosynthesis-Respiration Cycle in Plants   261

Photosynthesis for Tissue Growth   262

Animal Respiration   262

Respiration by Decomposers   262

Burial of Plant Debris and Atmospheric Chemistry   263

Aquatic Ecosystems   265

The Use of Isotopes to Study Global Cycles   266

Carbon Isotopes   266

Atmospheric Oxygen   268

Atmospheric Carbon Dioxide   269

The Importance of Weathering   270

Phanerozoic Trends in Atmospheric CO2   272

Negative Feedbacks: How CO2 Levels Are Held in Check   273

Temperature and Rates of Weathering   273

Precipitation and Rates of Weathering   274

Oxygen Isotopes, Climate, and the Water Cycle   274

Temperatures and Isotope Ratios in Skeletons   275

Salinity and Isotope Ratios   277

Volume of Glacial Ice and Isotopes   277

Ocean Chemistry and Skeletal Mineralogy   278

For The Record 10-1: Seawater Chemistry and Chalk   280

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CHAPTER 11

The Archean Eon of Precambrian Time   285

The Ages of the Planets and the Universe   289

The Origin of the Solar System   291

The Sun   291

The Planets   292

The Origin of Earth and Its Moon   293

Earth's Layers   293

The Catastrophic Birth of the Moon   294

Earth's Early Atmosphere   295

The Oceans   295

When the World Was Young   296

The Craters of the Moon   296

A Hotter Earth and Smaller Plates   297

The Origin of Continents   297

Hot Spots: Where Felsic Crust Forms   297

Why Archean Continents Remained Small   298

For The Record 11-1: The Threat from Outer Space   299

The Oldest Continental Crust   301

The Overall Growth of Continental Crust   301

Archean Rocks   302

General Features of Sedimentary Rocks   302

Greenstone Belts   302

Large Cratons Appear   303

Archean Life   306

The Fossil Record   306

Amino Acids   307

An RNA World?   308

Where Did Life Arise?   309

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CHAPTER 12

The Proterozoic Eon of Precambrian Time   315

A Modern Style of Orogeny   318

Global Events between 2.5 Billion and 1 Billion Years Ago   320

Early Proterozoic Glaciation   320

Early Proterozoic Life   321

The Buildup of Atmospheric Oxygen   323

The Neoproterozoic Era   325

Ice Ages   325

The Beginnings of Modern Life   325

The Explosive Evolution of Animals   325

The Expansion and Contraction of Continents   329

The Assembly of North America   330

Continental Accretion   330

A Larger Continent   332

For The Record 12-1: A Mountain of Gold   333

Middle Proterozoic Rifting in Central and Eastern North America   334

The Grenville Orogenic Belt   336

The Assembly and Breakup of Supercontinents   337

The Origin of the Supercontinent Rodinia   337

The Birth of the Pacific Ocean and America's West Coast   337

Another Supercontinent?   338

The Birth of Paleozoic Continents   338

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CHAPTER 13

The Early Paleozoic World   341

The Cambrian Explosion of Life   344

Early Cambrian Life   344

Later Cambrian Life   348

Ordovician Life   351

The Early Ordovician   351

The Great Ordovician Radiation of Life   352

Animal Life and the Decline of Stromatolites   354

Extinction and Diversity at Sea   354

Did Plants Invade the Land?   354

The Paleogeography of the Cambrian World   355

Episodic Mass Extinctions of Trilobites   357

Ordovician Paleogeography   357

Glaciation and Sea-Level Lowering   358

A Great Mass Extinction   360

Regional Examples   361

The Taconic Orogeny in Eastern Laurentia    361

Stability in Western Laurentia   364

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CHAPTER 14

The Middle Paleozoic World   369

A New Expansion of Life   372

Aquatic Recovery   372

For The Record 14-1: Jaws, Evolution, and Genetic Engineering   378

Plants Invade the Land   381

Animals Move Ashore   384

The Paleogeography of the Middle Paleozoic World   386

The Start of a New Glacial Interval   386

Late Devonian Mass Extinction   386

Regional Examples   389

Eastern North America   389

Euramerica   390

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CHAPTER 15

The Late Paleozoic World   399

Life   402

New Forms of Marine Life   402

Reefs and Aragonite Seas   404

Plant Life on Land   405

For The Record 15-1: Wetlands, Then and Now   406

Freshwater and Terrestrial Animals   409

The Paleogeography of the Late Paleozoic World   414

The Early Carboniferous Period: Limestone and Glaciers   414

Events at the Mid-Carboniferous Boundary   414

The Later Carboniferous Period: Continental Collision and Temperature Contrasts   414

The Permian Period: Climatic Complexity   416

Atmospheric Carbon Dioxide and Carboniferous-Permian Climate   418

The Late Permian Extinctions   418

The First of Extinction   418

The Terminal Extinction   418

Regional Examples   420

The Alleghenian Orogeny and the Appalachian Mountains   421

Earth Movements in the Southwestern United States   422

Coal within Cyclothems   426

The Permian System of West Texas   427

The Western Margin of North America   431

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CHAPTER 16

The Early Mesozoic Era   435

Life in the Oceans: A New Biota   438

Seafloor Life   438

Pelagic Life   439

Life on the Land   443

Land Plants: The Mesozoic Gymnosperm Flora   443

Terrestrial Animals: The Age of Dinosaurs Begins   444

For The Record 16-1: Who Were the Dinosaurs?   450

The Paleogeography of the Early Mesozoic World   452

Pangea During the Triassic Period   452

The Breakup of Pangea   453

The Jurassic World   454

Mass Extinctions   455

North America in the Early Mesozoic Era   456

Eastern Fault Basins   456

Western North America   458

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CHAPTER 17

The Cretaceous World   465

Life   465

Visual Overview: Major Events of the Cretaceous    466

Pelagic Life   468

Seafloor Life   470

The Rise of Modern Marine Predators   472

Flowering Plants Conquer the Land   472

Large Dinosaurs and Small Mammals   474

The Paleogeography of the Cretaceous World   476

New Continents and Oceans   476

For The Record 17-1: The Meek Did Inherit the Earth   477

Sea Level, Ocean Circulation, and Climates   479

The Terminal Cretaceous Extinction   482

Evidence of an Asteroid Impact   482

Consequences of the Impact   484

Lessons for Humanity   485

Fossils and the Timing of Extinction   485

The Aftermath   485

North America in the Cretaceous World   486

Cordilleran Mountain Building Continues   487

The Gulf Coast and the Seaway   487

The East Coast: Development of the Modern Continental Shelf   490

The Chalk Seas of Europe   490

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CHAPTER 18

The Paleogene World   495

Worldwide Events   498

The Evolution of Marine Life   498

The Evolution of Terrestrial Plants   499

Early Paleogene Terrestrial and Freshwater Animals   501

Mammals of the Oligocene Epoch   504

Climatic Change and Mass Extinction   505

For The Record 18-1: Global Warming in the Eocene   508

Regional Events   510

Antarctica and Global Change   510

The Top of the World: Changing Positions of Land and Sea   510

Tectonics of Western North America   511

The Gulf Coast   516

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CHAPTER 19

The Neogene World   519

Worldwide Events   522

Life in Aquatic Environments   522

Life on the Land   522

Late Neogene Climatic Change   526

Regional Events   536

Development of the American West   536

For The Record 19-1: The Biggest Flood on Record   544

The Western Atlantic Ocean and Its Environs   545

The Birth of the Caribbean Sea   546

The Great American Interchange of Mammals   546

The Destruction of the Tethyan Seaway   548

Human Evolution   549

Early Apes in Africa and Asia   549

The Australopithecines   550

Homo Erectus, Our Recent Ancestor   553

Neanderthal, Our Cousin   554

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CHAPTER 20

The Holocene   559

The Retreat of Glaciers   562

Abrupt Global Events of the Early Holocene   563

The First Americans   566

Sudden Extinction of Large Mammals   567

The Overkill Hypothesis   568

The Climate Hypothesis   569

A Possible Compromise: Both Hunting and Climate   569

Climatic Fluctuations of the Last 10,000 Years   569

The Beginnings of Agriculture   569

The Hypsithermal Interval   570

Glaciers, Tree Lines, and Tree Rings   571

Temperatures Since the Hypsithermal Interval   572

Episodes of Drying   573

Sea Level   574

Consequences of the Early Holocene Sea-Level Rise   574

Coastlines of the Past 7000 Years   574

The Twentieth and Twenty-First Centuries: The Impact of Humans   576

Human Activities and Greenhouse Warming   576

Methane from Tundra   577

Consequences of Future Climate Change   578

Direct Effects of Increased CO2 on Plants   578

Rising Sea Level   579

For The Record 20-1: A Future Meltdown in Antarctica?   580

Appendix: Stratigraphic Stages   584

Glossary   587

Credits   599

Index   601