1. PLATE TECTONICS: PLATE BOUNDARIES

2. PLATE TECTONICS the surface of the Earth is made of rigid plates  Size and position of plates can change over time  PLATE BOUNDARIES Edges of plates, where two plates “float” side-by-side, is where geologic activity takes place  Plates movement is from convection currents deep in the mantle  Size and position of plates can change over time  PLATE BOUNDARIES Edges of plates, where two plates “float” side-by-side, is where geologic activity takes place  Plates movement is from convection currents deep in the mantle

3. EARTH’S MAJOR PLATES: Pacific, N. American, S. American, African, Eurasian, Indian, Antarctic

4. CONVECTION CURRENTS MOVE THE PLATES

5. This continual movement (called convection currents) causes the crust to move in plate tectonics.

6. PLATE BOUNDARIES Divergent boundaries  plates move apart Convergent boundaries  plates move together Transform boundaries plates slide past 

7. DIVERGENT BOUNDARIES Make new crust When two plates move apart and magma surfaces forming NEW crust (usually oceanic) continental rift zones (landmass splits into two or more segments) mid-ocean ridges (sea-floor is elevated)

8. DIVERGENT BOUNDARIES Make new crust Rift valley continent-continent

9. DIVERGENT BOUNDARIES Make new crust: Sea Floor Spreading Youngest rocks form at ridge Older rocks are further from ridge Oldest rocks are located at subduction zones

10. DIVERGENT BOUNDARIES Make new crust: Sea Floor Spreading  As magma rises and cools, iron and magnesium minerals align themselves to the Earth’s magnetic field  “Magnetic Stripes” are formed  The Earth’s magnetic field reverses polarity  Magnetic stripes are mirrored on each side of the mid-ocean ridge  As magma rises and cools, iron and magnesium minerals align themselves to the Earth’s magnetic field  “Magnetic Stripes” are formed  The Earth’s magnetic field reverses polarity  Magnetic stripes are mirrored on each side of the mid-ocean ridge Every ~20,000 years the polarity of the Earth changes. This is change is reflected in the rocks, whose polarity is fixed once the magma is cooled.

11. CONVERGENT BOUNDARIES plates colliding  Destroys old crust and forms new mountains  Three types of convergent boundaries  Destroys old crust and forms new mountains  Three types of convergent boundaries

12. CONVERGENT BOUNDARIES plates colliding Continent-continent convergence: Folded mountains Continent-continent convergence: Folded mountains Ex Himalayas Eurasian/Indian plates

13. CONVERGENT BOUNDARIES plates colliding: Subduction Zones Subduction Zones: where ocean plates slide under another plate Creates magma which moves upward, pushing up the land above it. Magma/lava solidifies into intrusive/extrusive igneous rock Heat from the magma can change the rock around it. Rock that recrystallizes without melting becomes metamorphic rock.. Denser oceanic plates always subduct beneath less dense continental plates

14. CONVERGENT BOUNDARIES plates colliding Ocean-continent convergence: Trench & Coastal Volcanoes Ocean-continent convergence: Trench & Coastal Volcanoes Andes Mountains Nazca & S.American plates

15. CONVERGENT BOUNDARIES plates colliding Ocean-ocean convergence: Trench & Island arc Ocean-ocean convergence: Trench & Island arc

16. TRANSFORM BOUNDARIES When two plates slide past each other  no tearing or crushing - no damage occurs to the lithosphere  Faults –San Andreas Fault  Cause most earthquake damage  no tearing or crushing - no damage occurs to the lithosphere  Faults –San Andreas Fault  Cause most earthquake damage

17. Summary of Plate Movements Convection currents

18.  TASK….  Create a 3 column foldable of the boundaries  TASK….  Create a 3 column foldable of the boundaries DivergentConvergentTransform Picture- must have 3 colors Explanation with 2 important facts What do they create Explanation with 2 important facts What do they create Explanation with 2 important facts What do they create