1. Plate Tectonics

2. Theory of Plate Tectonics  Earth’s crust and part of the upper mantle are broken into sections  Sections of Earth’s crust = PLATES

3. Lithosphere Rigid layer of earth, made up of the crust and a part of the upper mantle

4. Asthenosphere Plasticlike layer below the lithosphere where plates float and move around

5. Plate Boundaries 1. DIVERGENT BOUNDARIES 2. CONVERGENT BOUNDARIES 3. TRANSFORM BOUNDARIES

6. Divergent Boundary  The boundary between two plates that are moving apart  TENSION- force that pulls the plates Features caused by divergent boundaries: Rift valleys and mid-ocean ridges

7. Convergent Boundary  When two plates collide (move towards each other)  COMPRESSION- force that pushes the plates. Features caused by convergent boundaries: Mountains and earthquakes

8. Subduction Zone  When an oceanic plate converges with a less dense continental plate, the denser oceanic plate sinks under the continental plate Features caused by subduction zones: Volcanoes

9. Transform Boundary  When two plates slide past one another (plates move in opposite directions)  SHEARING- force in transform boundary eatures caused by transform boundaries: Earthquakes, faults

10. Types of Faults Normal fault = the rock layers above the fault move down when compared with rock layers below the fault Reverse fault = the rock layers above the fault surface move up relative to the rock layers below the fault Strike-slip fault = rocks on opposite sides of the fault move in opposite directions, or in the same direction at different rates

11. Cause of Plate Tectonics  Convection (heat) = causes the movements of plates  Convection current: cycle of heating, rising, cooling, and sinking

12. Testing for Plate Tectonics Problem: Studying magnetic characteristics of rocks, volcanoes and earthquakes supported the theory but did not provide PROOF. Solution: New methods discovered to measure amounts of plate movement = satellites and lasers