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Earth’s Interior 355
Probing Earth’ s Interior: “Seeing” Seismic Waves 356
Formation of Earth’ s Layered Structure 356
Earth’ s Internal Structure 356
THE CHAPTER IN REVIEW 358 KEY TERMS 358
GIVE IT SOME THOUGHT 359 COMPANION
WEBSITE 359
15 Plate Tectonics:
A Scientific Revolution
Unfolds 360
From Continental Drift To Plate Tectonics 362
Continental Drift: An Idea Before its Time 363
Evidence: The Continental Jigsaw Puzzle 363
Evidence: Fossils Match across the Seas 364
Evidence: Rock Types and Geologic Features 365
Evidence: Ancient Climates 366
The Great Debate 367
• Plate Tectonics 368
Earth’ s Major Plates 369
Plate Boundaries 369
• Divergent Boundaries 369
Oceanic Ridges and Seafloor Spreading 369
Continental Rifting 371
• Convergent Boundaries 372
Oceanic–Continental Convergence 373
Oceanic–Oceanic Convergence 374
Continental–Continental Convergence 374
• Transform Fault Boundaries 376
Testing the Plate Tectonics Model 378
Evidence: Ocean Drilling 379
Evidence: Hot Spots 379
Evidence: Paleomagnetism 380
Apparent Polar Wandering 382
Magnetic Reversals and Seafloor Spreading 382
The Breakup of Pangaea 384
• How Is Plate Motion Measured? 384
Mantle Plumes and Plate Motions 385
Measuring Plate Motion from Space 385
What Drives Plate Motions? 386
Plate–Mantle Convection 386
Forces that Drive Plate Motion 387
Models of Plate–Mantle Convection 387
Plate Tectonics in the Future 388
THE CHAPTER IN REVIEW 390 KEY TERMS 390
GIVE IT SOME THOUGHT 390 COMPANION
WEBSITE 391
16 Origin and Evolution
of the Ocean Floor 392
• An Emerging Picture of the Ocean Floor 394
Mapping the Seafloor 394
Viewing the Ocean Floor from Space 395
Provinces of the Ocean Floor 396
• Continental Margins 397
Passive Continental Margins 397
Active Continental Margins 398
• Features of Deep-Ocean Basins 399
Deep-Ocean Trenches 399
Abyssal Plains 400
Seamounts, Guyots, and Oceanic Plateaus 400
Explaining Coral Atolls—Darwin’ s Hypothesis 400