Plate tectonics unit

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

​​Convergent

​scrape past one another.
- earthquakes

Transform

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

Divergent

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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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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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

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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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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