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Essential Questions

7.3 The Theory of Plate Tectonics

• What is the theory of plate tectonics?

• What are the three types of plate boundaries?

• What results from interactions of tectonic plates?

The Theory of Plate TectonicsVocabulary

• plate tectonics• divergent plate boundary• transform plate boundary• convergent plate boundary• subduction• convection

• Theory that suggests that the Earth’s surface is divided into large plates of rigid rock that move over the Earth’s hot and semi-plastic mantle.

plate tectonics

divergent plate boundary

•Places on the Earth’s crust that move apart as a result of pulling forces (tension) that act in opposite directions on each plate.•New Lithosphere is created at this boundaries.•Creates mid-ocean ridges and rift valleys

transform plate boundary

Plates that slide past each other at different speed and or direction. Causes: earthquakes and tsunamis

convergent plate boundaryWhen plates move toward each other, they collide, the outcome of the collision depends on the density of the plates involved. See below.

subduction•When and oceanic plate collides with an oceanic plate or with a continental plate, the denser plate sinks under the less dense one and forms a deep trench. •The subducting plate sinks into the mantle and melts. This is why the Earth doesn’t grow larger. •It destroys crust by melting it into the mantle.•Creates volcanic island chains, trenches and volcanoes.

convectionHeat transfer in fluids caused by differences in temperature and density. The hot molecules separate becoming less dense and rise, when they cool they get closer together become heavier and fall to the bottom to start the cycle over again.

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Earth’s crust is made of 14 tectonic plates that interact at their boundaries in various ways.

Lesson Main Idea

The arrows indicate whether the plates are convergent, divergent or transforming

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Texas Essential Knowledge And Skills

7.3 The Theory of Plate Tectonics

6.10(C) Identify the major tectonic plates, including Eurasian, African, Indo- Australian, Pacific, North American, and South American.

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Texas Essential Knowledge And Skills

Eurasian Plate

North American Plate

Pacific Plate

South American Plate

African Plate

Indo-Australian Plate

Antartic Plate

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Texas Essential Knowledge And Skills

7.3 The Theory of Plate Tectonics

6.10(D) Describe how plate tectonics causes major geological events such as ocean basins, earthquakes, volcanic eruptions, and mountain building.