1. Locations of Volcanoes
About 80% of volcanoes form at convergent plate boundaries
About 20% of volcanos form at divergent plate boundaries.
Hotspots: Occurs when a mass of hotter than normal mantle material (mantle plume) rises toward the surface. (There have been 40 hotspots identified.)
Ring of Fire: The area where a large number of earthquakes and volcanic eruptions occur in the basin of the Pacific Ocean.

2. Magma All volcanos are fueled by magma
In order to create magma, you must have temperature, pressure, and water

3. Magma vs. Lava
Viscosity: resistance to flow

4. Viscosity: resistance to flow
Viscous – thick, slow moving , typically cooler temperature
Less Viscous – thin, fast moving, typically hotter temperature
Viscosity depends on two factors:
Temperature (the cooler it is, more viscosity.)
Composition (higher the silica content, more viscosity)

5. Anatomy of a Volcano Neck: channels magma to crater
Vent: where magma reaches the surface
Crater / Caldera: bowl shaped depression that forms around the vent
Magma Chamber: storage chamber for magma, feeds magma to vent or neck
neck –

6. Types of volcanoes – shield
Gently sloping sides, circular base
Formed by layer upon layer of basaltic lava
Nonexplosive
Kohala, Hawaii

7. Types of volcanoes – cinder cone
Steep sides, cone shape
Have water and silica content in magma
Ejected material piles up around vent
Arizona

8. Types of volcanos – composite / Stratovolcano
Largest type
Larger amounts of silica, water and gas
Violent, explosive nature
Mt. Fuji, Japan

9. Volcanic Material
Lava Flow – flow of lava

10. Volcanic Material
Lava Flow – flow of lava Pyroclastic Flow – mixture of clouds of gas, ash, and rock fragments (can travel up to 200km/hr)

11. Volcanic Material
Lava Flow – flow of lava Pyroclastic Flow – mixture of clouds of gas, ash, and rock fragments (can travel up to 200km/hr) Ash Cloud – thin ash particles ejected into the atmosphere

12. 1,500 active volcanoes on earth

13. Intrusive magma formations
The structures that result from the cooling and hardening of magma at depth are called plutons.
All plutons form beneath earths surface
Uplifting and erosion expose them

14. Looking Glass Rock, NC
One of the largest masses of granite in the Eastern United States

15. Types of Igneous formations
Laccoliths – viscous magma that has collected, and intruded close to the surface
Looks like a mushroom
Batholith

16. Types of Igneous formations
Sills – forms when magma is intruded close to the surface
Looks like horizontal lava flows
Batholith

17. Types of Igneous formations
Dikes – form when magma is injected into fractures
Cuts across preexisting rock layers
Batholith

18. Types of Igneous formations
Batholiths – forms from cooled magma chambers
Largest intrusive formation
Batholith