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Sea Floor Spreading and Plate Tectonics

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Presentation on theme: "Sea Floor Spreading and Plate Tectonics"— Presentation transcript:

1 Sea Floor Spreading and Plate Tectonics
Chapter 1.4 and 1.5

2 Ch. 1.4 Sea-Floor Spreading
Mid-Ocean Ridge longest chain of mountains in the world all below the ocean Scientists use SONAR to map them SONAR -a device that records echoes of sound waves History of Ocean Drilling

3 2. Sea-floor spreading? At the mid-ocean ridge, molten material rises from the mantle and erupts. The molten material then spreads out, pushing older rock to both sides of the ridge. Earth's Volcanic History

4 3. Scientists found Evidence
Molten Material found as pillow-shaped rocks hardened quickly

5 3 . Scientists found Evidence
Magnetic patterns or stripes found in Ocean floor rock Reversals of Earth’s magnetic field

6 3. 3. Scientists found Evidence
Drilling core samples age of rock samples The farther away from the mid-ocean ridge, the older the rocks Drilling for Cores Samples

7 4. Subduction at Deep-Ocean Trenches
a process where the ocean floor sinks beneath a deep-ocean trench and back into the mantle… over tens of millions of years. Sketch this picture

8 Subduction at Earth’s Oceans
Drilling in the Arctic Ocean

9 Ch. 1.5 Theory of Plate Tectonics
Plate Motion Pieces of Earth’s lithosphere are in constant slow motion Driven by convection currents in mantle Theory of Plate Tectonics explains the Formation Movement Subduction of Earth’s plates

10 Plate Boundaries Plate boundaries are- where edges of lithosphere meet
Faults are- breaks in the crust, where rocks that slip past each other form at plate boundaries

11 3 Types of Plate Boundaries Transform boundaries
Where 2 plates slip past each other

12 Plate boundaries Divergent boundaries
Where 2 plates move apart A rift (deep) valley forms

13 2. Plate boundaries Convergent
Where 2 plates come together or collide The plate density determines which plate goes under-subduction Where continental crusts collide-it forms mountains

14 Plate boundaries

15 Continent’s Slow Dance
225 million years ago, plates joined together Pangaea mya Continents split apart, narrow seas become oceans 135 mya Continents began to drift apart 65 mya India a separate continent, Australia connected to Antarctica Today continents look like puzzle pieces that once were together Take Aim At Climate Change

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