Plate tectonics unit

A theory that states that pieces of Earth's lithosphere are in constant, slow motion, driven by convection currents in the mantle.

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Theory of plate tectonics

Open Ended

What is the theory of plate tectonics? (rewrite this paragraph with correct answers in the blanks): A _______ that states that pieces of Earth's ______________ are in _________, _____ _______, driven by ____________ currents in the _______.

​Plates come together.
- volcanoes, earthquakes, and trenches.

​​Convergent

​scrape past one another.
- earthquakes

Transform

plates pull apart.
- large rifts and new crust/ earthquakes.

Divergent

​Three types of plate boundaries:

Multiple Choice

What is a convergent boundary?

• A convergent boundary is where two tectonic plates remain stationary.
• A convergent boundary is where two tectonic plates move toward each other.
• A convergent boundary is where two tectonic plates slide past each other horizontally.
• A convergent boundary is where two tectonic plates move away from each other.

Multiple Choice

What is a transform fault boundary?

• A transform fault boundary is where two plates slide past each other horizontally.
• A transform fault boundary is where two plates rotate around each other
• A transform fault boundary is where two plates move apart
• A transform fault boundary is where two plates converge

Multiple Choice

What is a divergent boundary?

• A divergent boundary is where two plates remain stationary.
• A divergent boundary is where two plates slide past each other horizontally.
• A divergent boundary is where two plates move towards each other.
• A divergent boundary is where two plates move away from each other.

The heating and cooling of the fluid, changes in the fluid density, and the force of gravity combine to set convection currents in motion.

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What drives the earth's plates?

Open Ended

What drives the earth's plates? (Rewrite the paragraph fill in the blanks): The ___________ and cooling of the ________, changes in the fluid _________, and the force of __________ combine to set convection _________ in _________.

Plate movement results in earthquakes and volcanoes. This seismic activity clearly shows the plates when mapped. We can also identify and map plate boundaries with satellites.

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How do we know where they are?

Multiple Select

How do we know where earth's plates are located?

• Through the observation of earthquakes, volcanic activity, and the distribution of mountains and ocean ridges.
• Seismic activity clearly shows the plates when mapped.

• The heating and cooling of the fluid, changes in the fluid density, and the force of gravity combine to set convection currents in motion.

• We can also identify and map plate boundaries with satellites.

long mountain ranges on the ocean floors. They run through the middle of all oceans.
Iceland is the top of a mid-ocean ridge.

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Mid-Ocean Ridges

Multiple Choice

What is a mid-ocean ridge?

• An underwater mountain range formed by plate tectonics
• A desert ecosystem
• A deep-sea trench
• A type of cloud formation

In the center of the mid-ocean ridge, melted rock pushes up through cracks in the ocean floor. The melted rock pushes older, solid rock away from both sides of the ridge. The melted rock cools and forms new solid rock at the center of the ridge.

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Sea-Floor Spreading

Fill in the Blanks

The process that slowly adds new rock to the ocean floors is called ___ _________________.

Scientists used a submarine to get rocks from a mid-ocean ridge. Scientists used a drill to get rocks from below the ocean floor. Rocks closest were the newest.

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Evidence of Sea-Floor Spreading

Multiple Choice

What is evidence that the sea-floor is spreading?

• Tectonic plate movement
• Volcanic activity
• Meteorite impacts
• Magnetic striping patterns on the ocean floor