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Our Changing Earth.

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Presentation on theme: "Our Changing Earth."— Presentation transcript:

1 Our Changing Earth

2 What is a Theory? In science, it’s almost the same as a fact
Must be some sort of evidence to support a theory Even with evidence there is still debate about how true it is

3 Continental Drift Theory
Alfred Wegener said the world used to be one large land mass millions of years ago The land was called Pangaea Pangaea kept moving apart a few centimeters each year After millions of years it became the world we see today


5 Continental Drift Theory
Evidence for Continental Drift includes includes includes includes Continental Edges Rock Structures Same Fossils Climate fit like showed seen in evidence from found Mountains with similar features Puzzle Pieces Continental ice sheets On different continents

6 Plate Tectonics Plate Tectonics – a more advanced theory about how the continents move Explains that there are loose plates in the earth that shift causing: Oceanic Trenches Mountains Volcanoes Earthquakes.

7 How Do the Plates Move?

8 So… Continental Drift – theory that says continents drift around on plates Plate Tectonics – theory that explains WHY scientists believe the continental drift theory is true

9 Now it’s time for a… REVIEW

10 What is Continental Drift?
Theory that says the continents are moving on plates

11 What is Plate Tectonics?
Theory that explains WHY scientists think continental drift occurs It tells us how the earth’s plates move

12 Divergent Boundaries This is when the plates move apart
It happens mostly between oceanic plates The rising magma causes volcanoes and underwater mountains to be formed

13 Convergent Boundary When the two plates are in the OCEAN they collide and form deep trenches. When the two plates are on the CONTINENTS they collide to form mountains.

14 Transform (Sliding) Boundaries
This is when the plates slide past each other or move horizontally The sliding is what causes earthquakes This type of boundary is found in California

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