1. Plate Tectonics and Volcanoes

2. Layers of the Earth Crust: outer most layer of the Earth surface.
Mantle: right under the crust and is made of molten rock.

3. The Earth’s crust may appears as one solid shell, but it is not.
The crust is broken into pieces called tectonic plates.
They are, on average, about 50 miles thick.

4. Underneath the plates is the partially molten layer of the Earth, called the mantle.
The mantle is in a constant state of movement.
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5. Seven Major Plates 1) African Plate 2) Antarctic Plate
3) Eurasian Plate 4) Indo-Australian Plate
5) North American Plate
6) Pacific Plate )South American Plate

7. Types of Plate Boundaries
1) Divergent boundaries -- where new crust is generated as the plates pull away from each other.
2) Convergent boundaries -- where crust is destroyed as one plate dives under another.
3) Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other.
4) Plate boundary zones -- broad belts in which boundaries are not well defined and the effects of plate interaction are unclear.

9. Divergent boundaries occur along spreading centers, new crust is created by magma pushing up from the mantle.

10. Convergent Boundaries occur where plates are moving toward each other, and one plate sinks (is subducted) under another.
The location where sinking of a plate occurs is called a subduction zone.

12. Transform faults are found mostly on the ocean floor.
They commonly offset the active spreading ridges, producing zig-zag plate margins, and are generally defined by shallow earthquakes.

13. Plate-Boundary Zones involve at least two large plates and one or more microplates caught up between them, they tend to have complicated geological structures and earthquake patterns.

14. Key terms
CONTINENTAL DRIFT: The theory that the landmasses separated and moved to their present locations.
OCEANIC TRENCH: A deep depression in the ocean floor caused by the convergence of plates and the resulting subduction of one plate
MID-OCEAN RIDGES: Sub marine mountain ridges where new seafloor is created by seafloor spreading.
FAULT: An area of fracturing between rocks resulting from stress.

15. Volcanoes
Volcanoes: a vent in the earth's crust where lava, steam, and ashes, are expelled
Volcanoes are found in three states
extinct, dormant, and active. 
They form based on a few factors.
1) the fluidity of the lava (how runny it is)
2) the temperature of the lava.

16. Types of Volcanoes
Composite Volcanoes: have steep sides, and are very explosive because the lava is thick.
-deadliest of the volcano types.
Shield Volcanoes: have gentle slopes and are very wide, formed when lava is very hot and very runny.
Cinder Volcanoes: most common type of volcano with straight sides with steep slopes
- large summit crater

17. Composite

18. Shield Volcano

19. Cinder

20. Volcanoes are found along destructive (subducting) plate boundaries, constructive (divergent) plate boundaries and at hot spots in the earth's surface.
The Ring of Fire is a volcanic chain surrounding the Pacific Ocean.