1. 17.4
Cause of Plate Motions

2. Mantle Earth’s interior between the crust and the core
Large-scale motion is believed to be the mechanism that drives the movement of tectonic plates

4. Convection
Transfer of thermal energy by the movement of heated material from one place to another
Ex. Boiling water
Heat comes from radioactivity within the mantle

5. Convection Currents Cycle of warm water rising and cool water sinking
The cooling of matter causes it to contract slightly and increase in density
then it sinks due to gravity
Warmed matter is then displaced and forced to rise

6. Convection Currents Develop in the mantle
Move the crust and outermost part of the mantle
Transfer thermal energy from Earth’s interior to its exterior

7. Rising material spreads out, lifts and splits lithosphere at divergent boundaries
Downward movement pulls convergent boundaries

8. Ridge push Tectonic process associated with convection currents
Occurs when the weight of an elevated ridge pushes an oceanic plate toward a subduction zone

9. Slab pull
Tectonic process associated with convection currents in Earth’s mantle
Occurs as the weight of the subducting plate pulls the trailing lithosphere into a subduction zone.

10. In-Class Assignment/Homework