Plate Tectonics

​What is plate tectonics?

• a theory (cannot necessarily be tested)

• combination of theory of continental drift (Alfred Wegener) and seafloor spreading (Arthur Holmes) to explain how ​the continents move

• made of layers​ (lithosphere- top crust, A.K.A what we see of Earth's land, and asthenosphere- flowy lava mantle)

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​Why do plates move?

• seafloor spreading

• plates float on flowy upper mantle​ lava layer (asthenosphere)

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​What happens when plates move?

• plates push into each other

• move away from each other

• slide past each other​

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​What his the evidence?

• similar rock layers or formations on different continents

• similar glacier locations/ice coverings across continents

• shape of continents

• fossils found on different continents (fossil distribution)​

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​There are 3 types!

Plates crash (or push) into each other

Form:​

• volcanoes

• mountains

• earthquakes

• ​deep ocean trenches (because of subduction)

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​The crust is destroyed at convergent plate boundaries.

​Convergent

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Plates pull apart from each other

​Form:

• rift zones

• mid-ocean ridges (ocean volcanoes)

  • supports seafloor spreading​

​The crust is created at divergent plate boundaries.

​Divergent

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Plates slide past each other ​

​Form:

• earthquakes​

​The crust is neither created or destroyed, just transformed.

​Transform

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​What was Pangea?

Plate tectonics explains how the continents broke apart and moved to their current positions. Pangea wasn't the only supercontinent and scientists believe that there could be future supercontinents as well.​

​So what happened?

Around 225 million years ago, all current continents on Earth were connected as one supercontinent- Pangea.

​When was Pangea around?