1. 9.3 & 4: Theory of Plate Tectonics

2. lithosphere forms the thin outer shell of Earth and is broken into several pieces called plates
asthenosphere: solid, plastic layer of the mantle beneath the lithosphere
made of mantle rock that flows very slowly which allows plates to move on top of it

3. plate tectonics: theory that explains how large pieces of the lithosphere (plates) move and change shape
plates ride on the asthenosphere like blocks of wood float on water
continents and oceans are carried along on the moving plates like passengers are carried by a bus

4. plates can include continental crust, oceanic crust, or both

5. scientists have identified about 15 major plates
boundaries of the plates do not always match the outlines of continents

6. plate boundaries may be in the middle of the ocean floor, around the edges or within continents
three types of plate boundaries are divergent, convergent, & transform fault
each plate boundary has a characteristic type of geologic activity

8. divergent: where plates move apart area where new crust forms
Chapter 10
divergent: where plates move apart
area where new crust forms
usually found on the ocean floor
can also create volcanoes

10. convergent: where plates run into one another (come together)
Chapter 10
convergent: where plates run into one another (come together)
three types of convergent boundaries based upon types of plates that are colliding 10

11. Chapter 10
ocean/continental = ocean crust (is denser) is pushed down into the mantle, creating a trench

12. can also make a range of volcanic mountains called a continental volcanic arc
due to melting of the ocean plate in the mantle

13. ocean/ocean = one is pushed down into the mantle creating a trench
Chapter 10
ocean/ocean = one is pushed down into the mantle creating a trench 13

14. can also make a range of volcanic mountains that are in the ocean so are called a volcanic island arc

15. continental/continental = both are pushed up creating a mountain range
Chapter 10
continental/continental = both are pushed up creating a mountain range 15

16. transform fault: plates grind past each other
causes earthquakes
Chapter 10

17. How Does This Happen?
convention currents in the mantle are the driving force behind plate movements