1. Where the rock cycle begins
8.3 Types of Volcanoes
Where the rock cycle begins

2. Learning Targets
Describe the basic shapes of volcanoes
Compare the features of volcanoes
Describe the stages in the formation of volcanoes

3. How do volcanoes form?
Many layers of lava and ash mix together to make a volcano
Different types of volcanoes form from different mixes of ash, gas, and lava

5. Types of volcanoes What are the 4 main types of volcanoes?
Composite/Stratovolcano
Shield
Cinder cone
Supervolcano
Determined by type of magma and type of eruption

7. Composite volcano Stratovolcano
Most famous type of volcano
Tall mountain with volcanic vent running through the center
Viscous lava mixed with pyroclastic material; i.e. composite
What does strata- mean?
Layer
Each eruption = one layer
The type of volcano where a large steep mountain is formed from the buildup of layers of lave and volcanic ash is a composite volcano.
Lava that has a high viscosity and erupts explosively is most likely to form a composite volcano.
Composite materials (also called composition materials or shortened to composites) are materials made from two or more constituent materials with significantly different physical or chemical properties, that when combined, produce a material with characteristics different from the individual components.

8. Pyroclastic material held together with lava

13. Composite Volcano Eruption

14. Shield Volcano Shaped like a shield laid flat Wide, low volcanoes
Can be 100 miles wide
What type of eruption?
Effusive eruptions
What type of lava?
Low viscosity lava
No pyroclastic material
The type of volcano that is very wide and flat without steep sides is a shield volcano.
Lava that is less viscous, flows easily, and erupts effusively will spread out over a large area to form a shield volcano.

15. Shield Volcano Formation

18. Cinder Cones Smallest and most common Usually only erupt once
Sometimes form around other volcanoes
Formed by lava or pyroclastic material?
Only pyroclastic material; no lava
The most common and smallest type of volcano is a cinder cone.
Eruptions that rarely produce flowing lava and form small steep volcanoes made rimarily from pyroclastic material are characteristic of cinder cone volcanoes.
A cinder is a pyroclastic material. Cinders are extrusive igneous rocks. Cinders are similar to pumice, which has so many cavities and is such low-density that it can float on water. Cinder is typically brown, black, or red depending on its chemical content

19. Cinder Cone Formation

25. Supervolcanoes Huge volcanic features
Eruptions so powerful only a caldera remains
A caldera is a Volcanic Crater
Eruptions are rare, but can change global climate and life on earth
A lot is unknown due to rarity of eruptions
What volcano result in the largest and most explosive eruption? Supervolcano
Yellowstone is thought to be an example of the most dangerous type of volcano in which a single eruption could potentially change all life on the planet. supervolcano

27. Caldera of a Supervolcano

29. Mt. Pinatubo Eruption; not a supervolcano

30. Last Yellowstone supervolcano supereruption: 640,000 years ago
Yellowstone Magma Chamber
Mt. Pinatubo Magma Chamber

31. Types of volcanoes and causes
Composite
Subduction zones
Shield
Hot spots
Cinder cone
Variable
Supervolcano
Enormous hot spots under continents

32. Where the rock cycle begins
8.4 Volcanic Landforms
Where the rock cycle begins

33. Learning Targets
List and describe landforms created by lava
Explain how magma creates different landforms
Describe the processes that create hot springs and geysers.

34. Volcanic features Lava can form Lava domes: reforming volcanoes
Lava plateaus: lava erupted on flat ground
Volcanic islands: Island arc or hot spot chain
What type of rock is this? Extrusive Igneous
Magma can form
Intrusive igneous rocks
Small pebbles to huge batholiths
A batholith (from Greek bathos, depth + lithos, rock) is a large emplacement of igneous intrusive (also called plutonic) rock that forms from cooled magma deep in the Earth's crust.

35. Growing Lava Dome

36. Crater Lake; Caldera with Lava Dome

37. Cascades Lava Plateau

38. Lava Plateau: Like a flood that becomes solid rock

41. Remains of ancient magma (intrusive)
A batholith (from Greek bathos, depth + lithos, rock) is a large emplacement of igneous intrusive (also called plutonic) rock that forms from cooled magma deep in the Earth's crust.

42. Hot springs and Geysers
Water reacts with nearby magma to form
Hot springs: hot water under normal pressure
Geysers: hot water that erupts under high pressure
Why might people think this water has medicinal properties?
Hot water holds a lot of minerals
Water that is heated underground and erupts violently as a result of the build up of pressure creates a geyser.

48. Edge of Pyroclastic Flow