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Plate Tectonics

Learn about plate tectonics and the evidence for it, including coastlines fitting like a puzzle, matching mountain chains and rock formations, and fossils. Discover the three types of plate boundaries (divergent, convergent, and transform) and the phenomena associated with each. Explore the concept of hot spots and their effects on the Earth's surface.

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Plate Tectonics

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  1. Plate Tectonics

  2. The word “tectonic” means “to build.”

  3. So the evidence is • 1. Coastlines seem to fit like a puzzle. • 2. Matching mountain chains on separate continents. • 3. Matching rock formations on separate continents. • 4. Fossils of plants and animals on separate continents.

  4. Plate tectonics is a relatively new scientific concept, introduced 50 years ago Geez… 50 is SOOOOO OLD!!!

  5. Most scientists say there are about 17 plates. How do we know where the plate edges are?

  6. What makes these plates move? • Giant lithospheric ants? • A funky beat? • How ‘bout CONVECTION? Click on the lamp.

  7. Plate Tectonics

  8. The plates consist of an outer layer of the Earth, the lithosphere, • which is cool enough to behave as a rigid shell. • Occasionally the hot asthenosphere of the Earth finds a weak place in the lithosphere to rise as a plume • PLATE BOUNDARIES!!! Oh Behave

  9. There are THREE types of plate boundaries: • DIVERGENT Boundaries • where new crust is generated as the plates pull away from each other. • These occur mostly in the ocean • Rocks of crust feel tension stress

  10. Click below for an animation of divergent boundaries. • Click!

  11. DIVERGENT Boundaries • Results in the following: • Volcanoes a. mafic magma and lava b. islands are made 2. Earthquakes 3. Mountain chains 4. Rift zones or Valleys 5. Geothermal activity

  12. DIVERGENT Boundaries • Examples include: • Mid-Atlantic Ridge • Iceland • East African Rift Valley • East Pacific Rise

  13. DIVERGENT Boundaries • The Evidence is that the Sea Floor is spreading • Earth’s magnetic field reverses every million years • New magnetic rock in the ocean floor looks different.

  14. So the sea floor must be spreading! • Click here for an animation online.

  15. Evidence of sea floor spreading • Click here for an animation, explaining how scientists know the sea floor is spreading. SO WHAT?!? So what is slowly happening to the Atlantic Ocean???? That’s right…it’s getting BIGGER!

  16. Another animation here!

  17. mmm… hot syrup

  18. 2. CONVERGENT boundaries -- where crust is destroyed as one plate dives under another. This is also known as a SUBDUCTION BOUNDARY!

  19. Convergent Boundaries • Boundary in which two plates meet • Rocks of crust feel compression stress • Types of Convergent boundaries are shown in the table • All can result in earthquakes

  20. SO WHAT?!?So what is slowly happening to the Pacific Ocean???? That’s right…it’s getting SMALLER!

  21. Animation! L I Q U I D H O T M A G M A

  22. a number of long narrow, curving trenches thousands of kilometers long and 8 to 10 km deep cutting into the ocean floor. Trenches are the deepest parts of the ocean floor and are created by subduction. Animation!

  23. Burn baby burn, Disco inferno!!!

  24. Let’s see an animation! Wouldn’t that be grand?!

  25. 3. TRANSFORMboundaries -- where crust is neither produced (created) nor destroyed

  26. TRANSFORMboundaries • A boundary in which two plates slide laterally past one another. • Most are found on the ocean floor but some are on coastlines. • Rocks of crust feel a lot of stress

  27. TRANSFORMboundaries • Results in: • Earthquakes • No volcanoes (volcanoes DO NOT form along transform boundaries)

  28. TRANSFORMboundaries • Examples include: • Haiti Haiti is situated to the north of the Caribbean Plate, on a transform (slip/conservative) plate boundary with the North American Plate. The North American plate is moving west. This movement is not smooth and there is friction between the North American Plate and the Caribbean Plate. Pressure builds between the two plates until it is released as an earthquake.

  29. TRANSFORMboundaries • Examples include: 2. San Andreas Fault in California SO WHAT?!? So what is really going to happen to western California? Part of California will end up in the Pacific Ocean

  30. zone between two plates sliding horizontally past one another is called a transform-fault boundary • Most transform faults are found on the ocean floor. They commonly offset the active spreading ridges, producing zig-zag plate margins • San Andreas fault zone in California

  31. 4. Hot Spot • Not a plate boundary! • This is a place where there is a plume of magma under the middle of a plate. It can push up through the plate as the plate moves across the stationary hot spot

  32. 4. Hot Spot • Results in any or all of the following: • Geothermal geysers • Volcanoes • Earthquakes

  33. 4. Hot Spot • Examples include: • Hawaiian Islands • Yellowstone

  34. Volcanoes and the Hawaiian Islands

  35. Animation!

  36. Visualizing Eruptions

  37. Disco Stu is tellin’ YOU… This is the last Hawaiian Island above water, all the rest are DOWN LOW!!!

  38. A Review of Plate Boundaries • Click here!

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