exit chapter chapter 8.1 what is plate tectonics? 8.2 types of plate boundaries 8.3 causes of plate...
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88CHAPTER
8.1 What Is Plate Tectonics?
8.2 Types of Plate Boundaries
8.3 Causes of Plate Movement
8.4 Plate Movements and Continental Growth
CHAPTER OUTLINECHAPTER OUTLINE
Plate Tectonics
CHAPTER HOME
Alfred Wegner proposed the hypothesis of
continental drift to explain how a single land mass
had separated into separate continents, which
drifted apart.
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VOCABULARY8.1 What is Plate Tectonics?
Plate Tectonics
Fossil evidence found in South America and Africa support the hypothesis that the continents were once joined.
South America
Africa
Areas in which mesosaurus fossils have been found
plate tectonics
continental drift
mid-ocean ridge
CHAPTER HOME
Alfred Wegner proposed the hypothesis of
continental drift to explain how a single land mass
had separated into separate continents, which
drifted apart.
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VOCABULARY
Later discoveries supported the idea that the
continents had been connected, but demonstrated
that the continents were not “drifting” but attached to
moving lithospheric, or tectonic, plates.
8.1 What is Plate Tectonics?
Plate Tectonics
plate tectonics
continental drift
mid-ocean ridge
CHAPTER HOME
The theory of plate tectonics explains the
occurrence of volcanoes and earthquakes in
concentrated belts along plate boundaries.
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VOCABULARY8.1 What is Plate Tectonics?
Plate Tectonics
EarthquakesVolcanoes
plate tectonics
continental drift
mid-ocean ridge
CHAPTER HOME
Plate tectonics also account for a distinctive pattern
in the age and magnetism of rocks that spread out
from mid-ocean ridges on the ocean floor.
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VOCABULARY8.1 What is Plate Tectonics?
Plate Tectonics
Mid-Atlantic Ridge, Atlantic Ocean
East Pacific Rise, Pacific Ocean
plate tectonics
continental drift
mid-ocean ridge
CHAPTER HOME
Plates move apart at divergent boundaries. A rift
valley is an example of a divergent boundary on
land.
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VOCABULARY8.2 Types of Plate Boundaries
Plate Tectonics
Type of Boundary
Characteristic Features
Current Examples
Process Involved
Divergent
sea-floor spreading
•Mid-Atlantic Ridge•East Pacific Rise
•mid-ocean ridges•rift valleys•earthquake activity at fracture zones along mid-ocean ridges•volcanic activity
divergent boundary
rift valley
rift
convergent boundary
subduction boundary
deep-sea trench
collision boundary
transform boundary
CHAPTER HOME
Plates move toward each other at convergent
boundaries. One plate may subduct under the other,
as happens at deep-sea trenches, or the two plates
may collide.
88CHAPTER
VOCABULARY8.2 Types of Plate Boundaries
Plate Tectonics
Type of Boundary
Characteristic Features
Current Examples
Process Involved
ocean-ocean subduction
•islands of Indonesia•Mariana Islands
•deep-sea trenches•volcanic island arcs•earthquake activity
Convergent
divergent boundary
rift valley
rift
convergent boundary
subduction boundary
deep-sea trench
collision boundary
transform boundary
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Type of Boundary
Characteristic Features
Current Examples
Process Involved
Convergent
CHAPTER HOME
Plates move toward each other at convergent
boundaries. One plate may subduct under the other,
as happens at deep-sea trenches, or the two plates
may collide.
88CHAPTER
VOCABULARY8.2 Types of Plate Boundaries
Plate Tectonics
ocean-continent subduction
•western coast of South America
•deep-sea trench bordering continent•volcanoes along coast of continent•earthquake activity
divergent boundary
rift valley
rift
convergent boundary
subduction boundary
deep-sea trench
collision boundary
transform boundary
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CHAPTER HOME
Plates move toward each other at convergent
boundaries. One plate may subduct under the other,
as happens at deep-sea trenches, or the two plates
may collide.
88CHAPTER
VOCABULARY8.2 Types of Plate Boundaries
Plate Tectonics
Type of Boundary
Characteristic Features
Current Examples
Process Involved
Convergent
continent-continent collision
•Himalayas•high continental mountain chains•earthquake activity
divergent boundary
rift valley
rift
convergent boundary
subduction boundary
deep-sea trench
collision boundary
transform boundary
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Plates move past each other at transform
boundaries.
88CHAPTER
VOCABULARY8.2 Types of Plate Boundaries
Plate Tectonics
Type of Boundary
Characteristic Features
Current Examples
Process Involved
plates sliding past each other
•San Andreas Fault•North Anatolian Fault (Turkey)•fracture zones along mid-ocean ridges
•earthquake activity
Transform
divergent boundary
rift valley
rift
convergent boundary
subduction boundary
deep-sea trench
collision boundary
transform boundary
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and slab pull are
hypothetical models for the causes of plate
movements.
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Mantle convection,
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VOCABULARY8.3 Causes of Plate Movement
Plate Tectonics
Mantle convection
This image shows one model of how mantle convection may contribute to plate movement.
Mid-ocean ridgeDeep-sea
trench
Deep-sea trench
This image shows as section of the East Pacific Rise, a mid-ocean ridge.
ridge push,mantle convection
ridge push
slab pull
CHAPTER HOME
Plate movements have caused the positions of
Earth’s landmasses to shift over time. Scientists
think that all continents were once part of a single
landmass they call Pangaea.
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VOCABULARY8.4 Plate Movements and Continental Growth
Plate Tectonics
Pangaea
200 million years ago
Pathalassa Ocean Tethys
Sea
Pangaea
craton
terrane
CHAPTER HOME
Plate movements have caused the positions of
Earth’s landmasses to shift over time. Scientists
think that all continents were once part of a single
landmass they call Pangaea.
88CHAPTER
VOCABULARY8.4 Plate Movements and Continental Growth
Plate Tectonics
180 million years ago
Laurasia
Gondwana
Pangaea
craton
terrane
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CHAPTER HOME
Plate movements have caused the positions of
Earth’s landmasses to shift over time. Scientists
think that all continents were once part of a single
landmass they call Pangaea.
88CHAPTER
VOCABULARY8.4 Plate Movements and Continental Growth
Plate Tectonics
65 million years ago
North America
South America
Africa
India
Asia
Australia
Antarctica
Pangaea
craton
terrane
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CHAPTER HOME
Plate movements have caused the positions of
Earth’s landmasses to shift over time. Scientists
think that all continents were once part of a single
landmass they call Pangaea.
88CHAPTER
VOCABULARY8.4 Plate Movements and Continental Growth
Plate Tectonics
Modern Day
North America
South America
Africa
Europe Asia
Australia
Antarctica
Pangaea
craton
terrane
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CHAPTER HOME
Plate movements have caused the positions of
Earth’s landmasses to shift over time. Scientists
think that all continents were once part of a single
landmass they call Pangaea.
88CHAPTER
VOCABULARY8.4 Plate Movements and Continental Growth
Plate Tectonics
Scientists use fossils, the ages of rocks, and other geologic evidence to reconstruct past land movement.
Pangaea
craton
terrane
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The shapes of the landmasses have also changed.
At the core of each continent is a craton, the oldest
rock on the continent.
88CHAPTER
VOCABULARY8.4 Plate Movements and Continental Growth
Plate Tectonics
The North American craton
Canadian ShieldPlatform
Pangaea
craton
terrane
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The shapes of the landmasses have also changed.
At the core of each continent is a craton, the oldest
rock on the continent.
88CHAPTER
VOCABULARY8.4 Plate Movements and Continental Growth
Plate Tectonics
Processes associated with plate tectonics add new materials to a continent over time. For example, terranes are blocks of lithospheric plates that contribute to continental growth.
Pangaea
craton
terrane
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88CHAPTER
CHAPTER HOMEPlate Tectonics
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