1. Chapter 8
Volcanoes

2. How do volcanoes form?
When magma (melted rock) gets to Earth’s surface, it erupts and forms a volcano.
Ring of Fire – the area that many volcanoes are located by the plate boundary in the pacific ocean.

3. Where do volcanoes form?
Most volcanoes form at plate boundaries.
Magma Plumes/Hot Spots
Divergent
Boundaries
Convergent
Boundaries
summary
summary
summary
picture
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4. Hot Spots
A volcanically active area that is not near a tectonic plate boundary

5. What causes magma to form?
Magma needs 3 things:
Temperature-
Rock has to get really hot to melt
High temperature
Pressure-
Low pressure
This is found near the crust
Magma takes up more space than rock.
Fluid-
Rock that has fluids like water can melt more easily than dry rock

6. Review 8.1 Hot spot Magma Volcano Divergent boundary
Convergent boundary
Subduction
Locations of volcanoes
How magma forms
How rock melts
Mid-ocean ridge

7. What kind of volcanoes form at Divergent boundaries?
Mid Ocean Ridge
Mafic lava – thin, runny, dark
When lava erupts under the water it hardens quickly
New land
Sea floor spreading
Oceanic
crust
Oceanic
crust
Old land
Old land
magma
Rift zone – deep cracks that form as two plates separate.

8. What kind of volcanoes form at convergent boundaries?
Lava
comes from melted crust and melted mantle
mafic (rich in magnesium and iron) (thin, dark, runny)
felsic (rich in silica and feldspar)(thick, sticky, light in color)
Big explosion
Pyroclastic material – rocks, gas, ashes, large chunks
Pyroclastic flow
Can destroy everything in its path
700 degrees C super HOT!!

9. Vent – openings where lava is released.
Lava tubes- long pipelike structures created when the flow will cool and solidify on top while the interior continues to travel.
Magma chamber – the magma that feeds the eruption pools deep underground in this structure.

10. Shield volcano Lava quietly flows from the vent.
mountain covers a large area.
sides are gently sloped.
Mountain is dome-shaped.
wide tall mountain.
mafic lava – runny and dark.
Erupts over and over for a long period of time.
continuous non explosive eruptions.

11. Cinder cone volcano cinders and rock particles are blown into the air.
Mountain is small.
Mountain has steep sides.
lava and ash come out of small vents and spray out in the air. Pieces of hard lava fall on the ground (cinders).
cinders and ash build up around the vent to form a small, steep volcano
Example: Paricutin, Mexico

12. Composite volcano
violent eruptions sends up volcanic bombs, cinders and ash.
quiet volcanic flow follows the explosion. Alternating layers continue forming the mountain.
mountain is large.
Sides steep.
mountain is cone-shaped.
Erupts over and over for a long period of time.
also called strato volcano.
Example: Mt. Vesuvius, Italy.

13. Review 8.2
Lava
Rift zone
Mantle chamber
Pyroclasitc material
Mafic
Felsic
Shield volcano
Composite volcano

14. Effects of volcanic eruptions
Harmful
Volcanoes hurt/kill people
Destroys buildings and trees
Creates changes in the environment
Pyroclastic flows bury anything in its path.

15. Effects of volcanic eruptions
Harmful
Water mixed with ashes can cause floods and mudflows (lahars).

16. Effects of volcanic eruptions
Harmful
Hard to breathe
Damages crops

17. Effects of volcanic eruptions
Harmful
Ashes can block sunlight and make the world cooler for several years.
Affect Earth’s climate for several years.
Ash and gases released in the air can cause temperatures to go down.

18. Effects of volcanic eruptions
Helpful (benefits)
Volcanic rocks break down soil
Volcanic Soil contains nutrients for plant growth.

19. Effects of volcanic eruptions
Helpful (benefits)
Geothermal energy – people can pump hot water out of rocks to make electricity or to heat buildings.

20. Effects of volcanic eruptions
Helpful (benefits)
Volcanic rocks –used for build buildings, cat litter, soap, cleaners, and polishes

21. Review 8.3
Lahar
Geothermal water
Volcanic soil
Global effect of volcanic eruption
Uses of volcanic rocks.
Geothermal energy.
Large volcanic eruptions can cause…

22. Volcano movie

23. Chapter 8 Review Volcanoes Where volcanoes are formed
Divergent, convergent boundaries, and hot spots
3 types of volcanoes
How magma forms
Hazards and Benefits of volcanoes
Mantle plumes
Felsic magma
Mafic magma
Lahars
Lava
Subduction
Pyroclasitc material
Parts of a volcano