Ch4L1: Earth's Moving Surface
Presentation
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Science
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7th Grade
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Practice Problem
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Hard
Standards-aligned
Caitlin h
Used 2+ times
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9 Slides • 2 Questions
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Chapter 4 Lesson 1:
Earth's Moving Surface
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Plate Tectonics
The theory that Earth's surface is broken into large, rigid pieces that move with respect to each other.
These 15 tectonic plates slowly move over Earth's surface.
Some are big enough to support continents, some are tiny.
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What is a tectonic plate?
The crust and uppermost part of the mantle make up the lithosphere. It forms a rigid shell on the outside of Earth, but it is broken into tectonic plates.
The partially melted portion of the mantle below the lithosphere is the asthenosphere. It is hotter and bends more easily, and contributes to the movement of the tectonic plates.
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Multiple Choice
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Divergent Boundaries
A boundary where two plates move away from each other is a divergent boundary.
As the plates move apart, new crust forms between them.
The American and Eurasian Plate is a divergent boundary.
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Convergent Boundaries
A boundary where two plates move toward each other is a convergent boundary.
In some places, one plate is pushed under the other plate and down into the mantle. This is called subduction.
The Pacific Plate is being subducted under the North American Plate at the plate boundary near Alaska.
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Transform Boundaries
Two plates slide past each other at a transform boundary.
The boundary between the Pacific Plate and the North American Plate in California (the San Andreas fault) is an example of this.
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Why do tectonic plates move?
Convection is the circulation within fluids, caused by differences in density and thermal energy.
This occurs in Earth's asthenosphere. As the rocks are hot enough to bend easily, they can flow in a way similar to liquid.
Subduction also causes movement as once it begins, it will not end.
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Multiple Choice
Chapter 4 Lesson 1:
Earth's Moving Surface
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