1. Ch. 17 Notes Day 4
9/12/16

2. Objectives SWBAT explain the forces driving continental drift
SWBAT explain how these forces work together on a massive scale to shape our earth.

3. What Causes Plate Motions??

4. Answer in a Nutshell: Large scale motion in the mantle!!!!
1) Draw what happens in the mantle to cause Plate Motion.

5. Mantle Convection
Convection: transfer of thermal energy by the movement of heated matter
expansion=decrease in density=floats to the top
tectonic currents result from transfer of energy between Earth’s hot interior and its cooler exterior
flow at only a per centimeters per year
further causing the currents are the newly (cooler) subducting slabs of crust
2) Why could conduction currents be responsible for plate tectonics?

6. Boundaries and Currents
divergent: caused by rising heated mantle, pushes up and out
convergent: the cooling sinking mantle, sucks it downward
3) Up or down (hot or cold), which would be at a rift boundary, and which would be at a subduction zone?

7. Push and Pull
Ridge Push: forces in the mantle cause the asthenosphere to rise, the weight of he uplifted ridge is thought to push an oceanic plate toward the trench in the subduction zone
Slab Pull: the weight of the subducting plate helps pull the trailing lithosphere into the subduction zone. (most important)
4) What are the two Pushes and Pulls in Plate Tectonics?