1. Volcanoes 4/27/16
Key Question: What are the different types of volcanic eruptions?
Initial Thoughts:

2. Evidence 1: What is a volcano? Who can describe one?
A volcano is a place where material from the inside of the Earth is escaping to the surface.
The prime material involved is magma (or melted rock) that comes from the layer of the Earth known as the mantle.

3. There are three major types of volcanoes…
Shield volcanoes
Cinder cones
Stratovolcanoes
And one more for fun…
Supervolcanoes

4. Shield Volcano Demo
Why do you think the shield volcano is larger and flatter than other volcanoes?
A shield volcano is formed almost entirely from great amounts of liquid/watery lava. This is called low viscosity lava.
The lava flows out of a vent and slides down the side of the volcano, making a wide, gentle-sloping cone.

5. Shield Volcano – Mauna Loa
Mauna Loa, in Hawaii, is a shield volcano, and the largest volcano in the world! (32,000 feet when measured from the ocean floor).
Notice it’s low, broad shape.

6. Shield Volcano - Galapagos Islands (think Darwin)

7. Cinder Cone Volcano How do you think this volcano developed?
What type of eruptions created this volcano?
Make a prediction.

8. Stratovolcano (Composite)
How do you think this volcano developed?
What type of eruptions created this volcano?
Make a prediction.

9. Evidence 2 Student Project
Students will be researching and developing a model to demonstrate how the Cinder Cone and Stratovolcanoes (Composite) are created.
Have students begin their research on the different types of volcanic eruptions. They can do a modified lab write for each of the eruptions.

10. Evidence 2 Student Presentation
Students will be researching and developing a model to demonstrate how the Cinder Cone and Stratovolcanoes are created.
Students can present their presentations. They need to explain their research about the different types of eruptions and demonstration their eruptions.

11. Evidence 3 – Note Taking Shield volcanoes
Shield volcanoes can be a product of hot spots or oceanic vs. oceanic subduction
They are frequently islands

12. Shield Volcano rocks..
Are generally low in silica, which is the major combination of elements in the Earth
Silica is made of silicon and oxygen
Instead of having a lot of silica, shield volcanoes have more dense elements, such as iron and magnesium
This is why oceanic crust subducts (slides under the continental plate)… it is more dense than continental crust

13. Rocks associated with shield volcanoes…
Basalt
Gabbro

14. Hawaii, the perfect shield volcano
Created by a hotspot
Non-stop current eruptions since 1980!
Types of Lava: Bombs, lapilli, fountains, Pele’s tears, pahoehoe, a’a
Hawaii, the perfect shield volcano

15. Cinder Cones Relatively small in size, hundreds to 2,000 feet tall
Usually steep sided and cone shaped.
Found on the outskirts of all types of stratovolcanoes and shield volcanoes

16. Cinder Cone Eruptions Relatively small
Lava – called scoria - is thrown into the air, and cools before it falls back down around the vent, building the volcano relatively quickly.
Scoria is like crumbly “cinders”
 Often glowing, and beautiful.

17. Cinder Cone Volcano – Wizard’s Island, Crater Lake

18. Lava Butte, Oregon

19. Composite Volcanoes aka Strato-Volcanoes
Typically large, steep sided, up to 8,000 ft above their bases.
Have a crater at the summit which contains a central vent or a clustered group of vents.

20. Composite volcanoes Found near “subduction zones.”
Denser oceanic plates sliding beneath continental plates
Oceanic crust melts, rises through continental crust, creates chain of volcanoes

21. Composite Volcano Eruptions
Very violent, explosive and BIG!!!
Entire sides of mountain gone in a few seconds.

22. Composite Volcano eruptions…
Alternating eruptions of:
Ash (lots of it)
Tephra (rock)
Pyroclastic flows (a dense, destructive mass of very hot ash, lava fragments, and gases ejected explosively)
Lahars (mudflows)
Lava, although not far reaching

23. More about composite cones
Average life span of a million years
Most famous eruptions in human history
Ash can change global climate, temporarily
Many Cascades erupt towards the north instead of straight up. Why?
Northern sides of the volcanoes receive more sun, sun melts the ice and snow, water mixes with gasses causing acid, eats away at the rock, making it less stable

24. Historically cool… Mt. Vesuvius

25. A whole dead city, entombed in ash!

26. Stratovolcanoes and rocks…
Andesite
Diorite

27. Mt. Rainier (my favorite)

28. Mt. St. Helens
Before eruption
After eruption in 1980

29. Now onto supervolcanoes
Hold on to your hats, it’s the end of the world!

30. What are super volcanoes?
Super volcanoes are those that have extremely high levels of silica
This makes for crazy viscous (thick & “sticky”) lava, and HUGE eruptions
The lava is so viscous it doesn’t even allow for a cone shaped volcano

31. Types of rock
Rhyolite
Granite

32. So where can you find one…?

33. Yellowstone

34. Yellowstone Created by a hot spot
Evidence from the Snake River Valley of past eruptions and calderas
So explosive it clears away enough crust that low viscosity basalt can sometimes come up
Can change the course of geologic history

35. Track it’s path…

36. For now, it creates neat stuff.
Old Faithful Geyser
Hot springs

37. When it goes… 60 feet of ash! At ONCE!

38. What are the consequences of it blowing?
We could hear it blow in Washington
Ash goes into the layer of atmosphere called the stratosphere, which will remain and block sunlight
The entire Earth would cool, potentially causing an ice age
If no ice age, definitely crops would die and food shortages would occur
People are gonna die!

39. Locales Yellowstone Toba: Sumatra, Indonesia Long Valley Caldera, CA
Others (about a dozen around the earth)

40. So why haven’t we heard about this before? They’re infrequent!

41. Analysis
Explain what type of volcano would be the safest to live by and why.
What could be the possible effects of a stratovolcano erupting near a city or town?
What would you do to prepare for an eruption?

42. Summary
What did you think about volcanoes and volcanic eruptions before this lesson?
What did you learn about volcanoes and volcanic eruptions from this lesson? (Minimum of 4 sentences!!!)
What are some further thoughts or questions you have about volcanoes and volcanic eruptions?

43. Reflection
Explain what you would need in an emergency kit, if you lived close to a volcano.

44. Big Idea