1. Sci. 4-3
The Theory of Plate Tectonics
Pages

2. A. Plate Tectonics- a theory that the Earth’s lithosphere is divided into tectonic plates that move around on top of the asthenosphere.

3. B. 3 Possible Causes of Plate Tectonics
1) Ridge Push- the process by which an oceanic plate slides down the lithosphere-asthenosphere boundary

4. 2) convection- hot magma rises while cooler magma sinks since it is more dense. As it sinks, it heats up. As it rises, it cools. This is a continuous cycle. The motion of convecting mantle drags the plates.

5. 3) slab pull- because oceanic lithosphere is denser than the asthenosphere, the edge of the oceanic plate sinks and pulls the plate with it.

6. C. Plate Boundaries-
1) Convergent Boundary- 2 plates collide into each other

7. a) mountains usually occur
b) oceanic crust is denser than continental crust so it goes under when the 2 collide

8. c) subduction zone- the area where oceanic crust sinks down into the asthenosphere

9. 2) Divergent Boundaries- 2 plates pull apart from each other
a) Mid Ocean Ridges are at divergent boundaries.

10. 3) Transform Boundaries- 2 plates slide past each other
a) often produces Earthquakes

11. D. Global Positioning System (GPS)- a network of satellites used to measure the rate of tectonic plates movements