Plate Tectonics: A Unifying Theory - The Changing Earth: Exploring Geology and Evolution - page 28

OUTLINE
Introduction
Early Ideas About Continental Drift
What Is the Evidence for Continental Drift?
Earth's Magnetic Field
Paleomagnetism and Polar Wandering
Magnetic Reversals and Seafl oor Spreading
Plate Tectonics: A Unifying Theory
The Three Types of Plate Boundaries
GEO-INSIGHT: Tectonics of the Terrestrial Planets
Hot Spots and Mantle Plumes
Plate Movement and Motion
The Driving Mechanism of Plate Tectonics
Plate Tectonics and the Distribution of Natural Resources
Plate Tectonics and the Distribution of Life
GEO-FOCUS: Oil, Plate Tectonics, and Politics
Geo-Recap

OBJECTIVES
At the end of this chapter, you will have learned that
Plate tectonics is the unifying theory of geology and has
revolutionized geology.
The hypothesis of continental drift was based on considerable
geologic, paleontologic, and climatologic evidence.
The hypothesis of seafl oor spreading accounts for continental
movement and the idea that thermal convection cells provide
a mechanism for plate movement.
The three types of plate boundaries are divergent, convergent,
and transform. Along these boundaries new plates are formed,
consumed, or slide past one another.
Interaction along plate boundaries accounts for most of
Earth's earthquake and volcanic activity.

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An earthquake survivor walks among the ruins of houses in Bantul, central
Indonesia, where a 6.3-magnitude earthquake on May 27, 2006, left more
than 6200 dead and more than 200,000 people homeless. Devastating
earthquakes such as this are the result of movement along plate boundaries.
Such earthquakes are part of the interaction between plates and, unfortunately
for humans, will continue to result in tremendous loss of life and property
damage in seismically active areas.

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