1. Take out homework and Work on homework
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Take out homework and Work on homework

2. 6.1 Objectives:
You will learn to describe how volcanoes can affect people.
You will learn to list conditions that cause volcanoes to form.
You will learn to identify the relationship between volcanoes and Earth’s moving plates.

3. VOLCANOES

4. Chapter 6

6. Volcanoes and
Earth’s Moving Plates

7. What are volcanoes? - openings in Earth’s surface
- mountains formed by lava & volcanic ash
- most are dormant
- Mt. St. Helens is the largest in North America
- Kilauea, Hawaii is the most active in the world
- more than 600 are active

8. - may cause lung disease
Effects of Eruptions
- collapsed buildings
- blocked roads
- may cause lung disease
in people and animals

9. How do volcanoes form?
Heat and pressure causes rock to melt and form magma
2. Magma is less dense than other rock and is forced upward
3. After thousands/millions of years it reaches Earth’s surface and flows out through a vent
4. Steep wall around the vent is the crater

10. Where do volcanoes occur?

11. 1. Divergent Boundaries
where plates move apart - form long deep cracks (rifts)
ex. Mid-Atlantic Ridge
formed Iceland

12. 2. Convergent Boundaries

13. ex. Mount St. Helens in the Cascade Range
plates move together
ex. Pacific Ring Of Fire
ex. Mount St. Helens in the Cascade Range

15. Mt St. Helens

16. 3. Hot Spots
area at the boundary between Earth’s mantle and core that is hotter than other areas
magma is forced upward towards the crust
ex. Hawaiian Islands

18. Let's Review! gases ash lava lava flows pyroclastic flows falling ash
A volcano is an opening in Earth’s surface that erupts ________, ________, and ________.
Direct effects of volcanic eruptions, can be caused by ______________, ______________, and ______________.
Volcanic eruptions also produce indirect effects, such as ________.
Volcanoes form when magma is forced up and flows onto Earth’s surface as ________.
A ________ is a steep-walled depression around a volcano’s vent.
Volcanoes form when one plate ________ beneath another plate, where two plates are moving ________, and at ________.
gases
ash
lava
lava flows
pyroclastic flows
falling ash
acid rain
Let's Review!
lava
crater
sinks
apart
hot spots

19. THE END

20. Get and begin Notes Packet
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Get and begin Notes Packet

21. Students will learn to list three forms of volcanoes.
6.2: Types of Volcanoes
Objectives:
Students will learn to explain how the explosiveness of a volcanic eruption is related to the silica and water vapor content of its magma.
Students will learn to list three forms of volcanoes.

22. Mount St. Helens –
sequence of eruptions

23. What controls eruptions?
1. amount of water vapor and other
gases trapped in the magma
2. amount of silica present
in the magma

24. 3 Types of Eruptions Exist:
1. Quiet
2. Explosive/Violent
3. Quiet/Explosive

25. basaltic magma contains less silica and is very fluid
1. Quiet
basaltic magma contains less silica and is very fluid
example: Kilauea

26. 2. Explosive/Violent
granitic magma contains a lot of silica, is very thick, and gets trapped in vents causing pressure
has a high water content

27. Quiet/Explosive
- Andesitic magma is more silica rich than basaltic magma, but less silica rich than granitic magma
- Because of a higher silica content than basaltic, these volcanoes erupt more violently than basaltic magmas

28. Forms of Volcanoes

29. - broad with gently sloping sides
Shield Volcano!!!
- quiet eruption
- basaltic lava
- broad with gently sloping sides
- ex. Hawaiian Islands

35. - throws tephra in the air
Cinder Cone Volcano!!!
explosive
- throws tephra in the air
- steeps sides

40. Composite Volcano!!! Sometimes called a Stratovolcano
Varies between quiet and violent
Tephra and lava layers are repeated over and over

43. Mt. Fuji, Japan

44. Mt. Rainier, Washington

46. Let's Review... water vapor eruption silica silica rich silica poor
The amount of _____________ and other gases control the type of __________ and the amount of _______ present in the magma.
Magma can be divided into two major types – ___________ and ____________.
A ________ volcano is a broad, gently sloping volcano formed by quiet eruptions of basaltic lava.
A ____________ volcano is a steep-sided, loosely packed volcano formed from tephra.
___________ volcanoes are formed by alternating explosive and quiet eruptions that produce layers of tephra and lava.
eruption
silica
silica rich
silica poor
shield
cinder cone
Composite

47. the end

48. Review: What factors control the type of eruptions that occur?
Do Now!!!
Review: What factors control the type of eruptions that occur?

49. You will learn to explain how a volcanic neck and a caldera form.
Objectives!!!
You will learn to describe intrusive igneous rock features and how they formed.
You will learn to explain how a volcanic neck and a caldera form.

50. 6.3: Igneous Rock Features!!!
- rock cooled
under ground

51. largest intrusive igneous rock forms when magma cools underground
Batholiths
largest intrusive igneous rock
forms when magma cools underground
some have been exposed due to erosion

52. YOSEMITE
STATE
PARK

53. Magma squeezed into vertical cracks
Dike
Magma squeezed into vertical cracks

54. Magma squeezed into horizontal cracks
Sill
Magma squeezed into horizontal cracks

55. Solid igneous rock in the vent after cone has eroded away
Volcanic
Neck
Solid igneous rock in the vent after cone has eroded away

57. Devils Tower

59. Top of volcano collapses
Caldera
Top of volcano collapses

60. Crater Lake
( 1,932 ft. deep)

61. Diameter is 5 miles

63. Intrusive igneous rock features
Let's Review!!!
Intrusive igneous rock features
_______________________________ are formed from magma that is forced upward toward Earth’s crust, then slowly cools and __________ underground _______ reaching the surface.
__________, ______, and _____ are a few examples of intrusive igneous rock features.
A ______________ is the solid igneous core of a volcano left behind after the softer cone has been ________.
A _______ is a large, circular-shaped ___________ that forms when the top of a volcano collapses.
solidifies
before
Batholiths
dikes
sills
volcanic neck
eroded
caldera
depression

64. The End