1. Plate Tectonics

2. Plate Tectonics http://education. nationalgeographic

3. Continental Drift
Alfred Wegner—1st to propose the theory of continental drift
His theory– Continents were once a single landmass then, over time, they broke up and drifted to where they are today

4. Wegner’s Evidence of Continental Drift
Fossil Evidence
Rock formations
Climatic Evidence
Geographic Evidence

5. Fossil Evidence

6. Let’s do a puzzle!
Fossil puzzle…match up the fossils on the continents to view Wegner’s evidence of continental drift

7. Rock Formations
Just like fossils, similar rock formations were found on different continents

8. Climatic Evidence
Shows that land used to have different climates than is natural to have in the current position of the land
Example: Tropical plant fossils
were found in Antarctica

9. Geographic Evidence
Shapes of continents look like they fit together and have similar geographical features

10. FYI
*As continents rift or as mountains form, populations of organisms are separated.
When populations of organisms are separated, new species may evolve from existing species.
*Similar rock formations and fossil evidence supported Wegener’s evidence.

11. Mid-Ocean Ridges
--a place where crust is spreading an creating new ocean floor --a place where old crust is recycled (this process makes oceanic crust younger than continental crust)

12. Lets make a mid-ocean ridge!
ACTIVITY!!!!!!!!!
Lets make a mid-ocean ridge!

13. Sea-Floor Spreading
Harry Hess hypothesized that the valley at the center of mid-ocean ridges was a crack in the Earth’s crust
At this crack, magma rises up to form new sea floor which cools and forms new sea flooring
This process is known as sea-floor spreading

14. Layers of our Planet

15. Layers of our Planet
Lithosphere – the solid, outer layer of Earth that consists of the crust and the rigid upper part of the mantle
Asthenosphere – The solid, plastic or putty-like layer of the mantle beneath the lithosphere. Made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it

16. Theory of Plate Tectonics
This is the theory that explains how large pieces of lithosphere called plates, move and change shape

17. Tectonic Plates
Scientists have identified about 15 major plates:

18. Plate Tectonics Activity

19. Types of Plate Boundaries

20. Divergent Boundaries
These types of boundaries move AWAY from each other
Examples: Mid-ocean rifts, the Red Sea (between the African and Arabian Plates)

21. Convergent Boundaries
Plates collide together at these types of boundaries
Examples:
Areas of subduction
Mountain ranges
Ocean trenches
trench

22. Transform Boundaries
A boundary at which two plates slide past each other horizontally
Example:
San Andreas Fault in
California

23. The Supercontinent Cycle
The process by which supercontinents form and break apart
This happens because tectonic plates of the Earth are always moving, though very slowly

24. 450 Million Years ago
Near the end of the Precambrian time Earth’s continents were separated…not as much land was above water as today

25. 250 Million Years Ago
By the end of the Permian Period, Pangaea had formed

26. 150 Million Years Ago
Pangaea had split into two continents, Laurasia and Gondwanaland

27. 60 Million Years Ago
Continents were moving toward their current positions on Earth

28. Future?
Scientist propose that in about 250 million years the earth might look like this: