1. Plate Tectonics Chapter 10

2. POD 2/5/08
1. Summarize the theory of plate tectonics. Using arrows to draw/label the three types of plate boundaries. Give an example of each.

3. Problem of the Day (POD) 1/30/08
1. Who proposed the theory of continental drift. What mechanisms led to this theory being accepted in the science community?

4. POD 2/1/08
1. How are tectonic plate boundaries related to earthquakes? What are the three types of plate boundaries?

5. Section 1 Objectives
Summarize Wegener's hypothesis of continental drift.
Describe the process of sea-floor spreading.
Identify how paleomagnetism provides support for the idea of sea-floor spreading.
Explain how sea-floor spreading provides a mechanism for continental drift.

6. Wegner’s Hypothesis 1912 German Scientist Proposed Continental Drift
Supercontinent- began breaking into smaller continents 250 million years ago
Over millions of years continents drifted to present locations

7. Evidence to Support Fossil Evidence Fossils of same plant and
animals found in areas that
had once been connected
Rock Formations
Ages and types of rocks in
coastal regions matched closely
Western Africa and Eastern South America

8. Evidence to Support Climatic Evidence Geologists discovered layers
of debris from ancient glaciers in
Southern Africa and South America
Areas today are to warm for glaciers
Missing Mechanisms
Idea strongly opposed and rejected
Continents plowed through ocean floor
Easily disproved by geologic evidence

9. Mid-Ocean Ridges 1947 scientists set out to map Mid-Atlantic Ridge
Findings
Rocks closer to the ridge
are younger than rocks
farther from the ridge
Ocean floor is very young
175 million years
Rocks on land 3.8 billion

10. Sea-Floor Spreading H.H. Hess- proposed sea-floor spreading
Center of a ridge has a crack or rift in Earth’s crust
Sea Floor Formation
Earth rises to fill crack
As ocean floor moves outward
Magma cools and solidifies
Hypothesis- Wegener's missing mechanism
If the ocean floor was moving, so were the continents?

11. Paleomagnetism Earth’s magnetic field not always pointed north
Magnetic Reversals
magnetic field north= normal polarity
Magnetic field south= reversed polarity
Pattern alternating normal/reversed
Geomagnetic Reversal Time Scale
Magnetic Symmetry
Match magnetic patterns on each side of mid-ocean ridge- rock ages could be assigned

12. Wegener Redeemed Magnetic patterns show changes over time
Sea-floor spreading provided a way for continents to move over Earth’s surface
Became accepted in scientific community
Mechanism that verified Wegener’s hypothesis

14. Section 2 Objectives Summarize the theory of plate tectonics.
Identify and describe the three types of plate boundaries.
List and describe three causes of plate movement.

15. How Continents Move
Continents and Oceans are carried along moving tectonic plates
Lithosphere
Upper part of mantle
Broken into tectonic plates which ride asthenosphere
Asthenosphere
Plastic rock
Earth’s Crust
Oceanic and Continental

16. Tectonic Plates Scientist Identify 15 major tectonic plates
By way of Earthquakes and Volcanoes
Three Types of Plate Boundaries
Divergent
Convergent
Transform

18. Divergent Boundaries Two plates move away from each other
Commonly found on ocean floor
Magma rises as plates move apart forming new lithosphere Mid-ocean ridges

19. Convergent Boundaries
Two plates collide with one another
Continental-Oceanic= subduction
Continental-Continental= uplift
Oceanic-Oceanic= deep-ocean trench/island arc

20. Transform Boundaries
Two plates slide past one another Scrape and cause stress= earthquake No magma is produced San Andreas fault

21. Causes of Plate Motion Mantle Convection
Hot material rises- cooler denser material flows away

22. Causes of Plate Motion
Ridge Push Cooling rock sinks forcing plate away from mid-ocean ridge

23. Causes of Plate Motion
Slab Pull Plates pull away from each other at mid-ocean ridges

26. Section 3 Objectives
Identify how movements of tectonic plates change Earth’s surface.
Summarize how movements of tectonic plates have influenced climates and life on Earth.
Describe the supercontinent cycle.

27. Pyramid
Place sheet of paper in front of you. Fold lower left corner of the paper diagonally to the opposite edge of the paper.
Cut off the tab of paper created by the fold.
Open paper so that it is a square. Fold lower right corner of the paper diagonally to the opposite corner to form a triangle.
Open the paper. The creases of the two folds will have created an X.
Using, scissors, cut along one of the creases. Start fron any corner, and stop at the center point to create two flaps. Attach one of the flaps on the other.

28. Reshaping The Earth’s Crust Side 1
Define rifting
How does the Earth’s crust break/crack?
Define terrane.
List 3 characteristics of terranes
Where do terranes become part of the continent?

29. Effects of Continental Change Side 2
What effects a continents climate?
What Geologic evidence supports changes in climate?
How are species/populations affected from continetal rifting or the formations of mountains?

30. Supercontinent Cycle Side 3
Why supercontinents form?
Formation of Pangaea- time/mountain ranges
Breakup of Pangaea
The Modern Continents
On the bottom of your pyramid list three changes in geography that are likely to happen in the future

31. Reshaping Earth’s Crust
Rifting
Process by which a continent breaks apart

32. Terranes and Continental Growth
Terrane- unique geologic history Contains rock and fossils Major fault boundaries Properties do not match neighbors Small volcanic islands, sea-mounts, atolls

33. Effects of Continental Change
Changes in Climate
Ice covered most of Earth’s surface- even the Sahara
Ice sheet formed when continents were close
Global temperatures changed as continents drift
Changes in Life

34. Effects of Continental Change
Changes in Life As continents rift mountains form, organisms are separated New species evolve

35. The Supercontinent Cycle

36. Geography of the Future