Welcome to Science 9/20

1. Welcome to Science 9/20 • Get out your lab and your Ch. 7 Section 3 Notes and on your small paper answer the following question: • What do you think is the driving force that causes the Earth’s tectonic plates to move? • Today’s Schedule • 1. Ch. 7 Section 3 Notes/Discussion • 2. Review Sea-Floor Spreading Lab

3. What We Know So Far

4. What We Want To Know • What causes the plates to move? • THE answer to this question we believe is: convection currents in the mantle. • animation

5. Convection • Convection- heat transfer by the movement of currents within a fluid • Caused by differences of temp. and density within the fluid

6. Convection Currents in Earth • 1. What is the heat source? • 2. What is flowing? • Heat from the core and the mantle itself causes convection currents in the mantle. • Google Image Result for http://www.windows.ucar.edu/earth/interior/e_thermal_history_animated.gif

7. Convection Currents in the Earth • Animation • As the convection currents move through the mantle, it causes the plates to move in the lithosphere.

8. What do you see here? • Plate Boundaries

9. Welcome to Science 9/21 • Get out the Ch. 7 Section 3 Notes • Today’s Schedule • 1. Question of the Day • 2. Experiment of the Day • 3. Finish Notes/Discussion • 4. Plate Tectonics Computer Activity

10. Question of the Day • A decrease in the amount of sea otters can lead to an increase in sea urchins. An increase in the sea urchin population results in less kelp. Kelp provides fish with protection from predators. What does this chain of events demonstrate? • A. living things grow • B. living things depend on only other living things • C. living things depend on other living and nonliving things • D. living things do not depend on each other

11. Plate Boundaries • Divergent Boundary- place where 2 plates move apart or diverge. • Most DB’s are at mid-ocean ridges. • On land DB’s form deep valleys called rift valleys • Fig. 19.21 - Evolution of a Divergent Plate Boundary • animation

12. Convergent Boundary • Place where 2 plates come together, or converge. • Oceanic plate + Continental plate = subduction • Continental plate + Continental plate =mountains • OptIPuter Outreach

13. Subduction at Trenches • Deep-ocean trench- underwater canyon where ocean crust sinks into the mantle. • Subduction- process by which ocean crust sinks beneath a deep-ocean trench and back into the mantle • Subduction Animation - Earthguide Online Classroom

14. Transform Boundary • Place where two plates slip past each other in opposite directions. • Transform Boundaries = Earthquakes • Observe animations of processes that occur along plate boundaries. • animation

15. land masses have slowly moved over time Plates move on top of asthenosphere Two plates slip past each other in opposite directions Happens at divergent boundaries, allows magma to rise to the ocean floor Two plates collide with each other Two plates separate with each other Convergent boundary Sea-floor spreading Plate tectonics Continental drift Divergent boundary Transform boundary Matching Game

16. Plate Boundaries Contest

17. Ch. 7 Section 3 The Theory of Plate Tectonics Things you should know: what plates are, directions plates move, and some landforms that plate movement creates. Now, you need to figure out what causes the plates to move. Observe these demonstrations to discover the answer.