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18 Plate
18

Tectonics

All of the rocks that you can see on Earth’s surface are part of a very thin
veneer, barely covering the surface of Earth.

CORE CONCEPT

Earth has an internal structure and cycles materials
between the surface and the interior.

OUTLINE

18.1 History of Earth’s Interior
Earth’s Internal Structure 18.2 Earth’s Internal Structure Earth’s Internal Structure
Seismic waves are vibrations in The Crust Data from seismic waves indicate
The Mantle
Earth that are generated by a that Earth’s interior can be
The Core
disturbance such as an explosion broken down into three zones:
A More Detailed Structure
or an earthquake. A Closer Look: Seismic Tomography crust, mantle, and core.
18.3 Theory of Plate Tectonics
Evidence from Earth’s Magnetic Field
A More Detailed Structure Evidence from the Ocean A More Detailed Structure
Data from seismic waves indicate Lithosphere Plates and Boundaries The crust and upper mantle
Divergent Boundaries
that a hot, elastic layer extends Convergent Boundaries above the asthenosphere are
around Earth in the upper A Closer Look: Measuring Plate Movement called the lithosphere, and it
mantle, and this layer is called Transform Boundaries is a rigid plate floating in the
the asthenosphere. Present-Day Understandings asthenosphere.
People Behind the Science:
Harry Hammond Hess
Science and Society: Geothermal Energy
Theory of Plate Tectonics Present-Day Understandings
Earth’s surface is broken into a Ideas about what moves tectonic
number of rigid plates that move, plates include convection in the
explaining the occurrence of mantle, ridge-push, and slab-pull.
earthquakes and volcanoes.

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