8.3 types of volcanoes where the rock cycle begins
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8.3 TYPES OF VOLCANOES
Where the rock cycle begins
Learning Targets
1. Describe the basic shapes of volcanoes
2. Compare the features of volcanoes3. Describe the stages in the
formation of volcanoes
How do volcanoes form?
1. Many layers of lava and ash mix together to make a volcano
2. Different types of volcanoes form from different mixes of ash, gas, and lava
Types of volcanoes
1. What are the 4 main types of volcanoes?
a)Composite/Stratovolcanob)Shieldc) Cinder coned)Supervolcano
2. Determined by type of magma and type of eruption
Composite volcano Stratovolcano
1. Most famous type of volcano2. Tall mountain with volcanic vent
running through the center3.Viscous lava mixed with
pyroclastic material; i.e. composite
4. What does strata- mean?a)Layer
5.Each eruption = one layer
Pyroclastic material held together with lava
Composite Volcano Eruption
Shield Volcano
1. Shaped like a shield laid flat2.Wide, low volcanoes
a) Can be 100 miles wide
3. What type of eruption?a)Effusive eruptions
4. What type of lava?a)Low viscosity lava
5.No pyroclastic material
Shield Volcano Formation
Cinder Cones
1. Smallest and most common2. Usually only erupt once3. Sometimes form around other
volcanoes4. Formed by lava or pyroclastic material?
a)Only pyroclastic material; no lava
Cinder Cone Formation
Supervolcanoes
1. Huge volcanic features2. Eruptions so powerful only a caldera
remains3. A caldera is a Volcanic Crater4. Eruptions are rare, but can change
global climate and life on earth5. A lot is unknown due to rarity of
eruptions
Caldera of a Supervolcano
Mt. Pinatubo Eruption; not a supervolcano
Yellowstone Magma
ChamberMt. Pinatubo
Magma Chamber
Last Yellowstone supervolcano supereruption: 640,000 years ago
Types of volcanoes and causes
1.Compositea)Subduction zones
2.Shielda)Hot spots
3.Cinder conea)Variable
4.Supervolcanoa)Enormous hot spots under
continents
8.4 VOLCANIC LANDFORMS
Where the rock cycle begins
Learning Targets
1. List and describe landforms created by lava
2. Explain how magma creates different landforms
3. Describe the processes that create hot springs and geysers.
Volcanic features
1. Lava can forma) Lava domes: reforming volcanoesb) Lava plateaus: lava erupted on flat
groundc) Volcanic islands: Island arc or hot
spot chaind) What type of rock is this? Extrusive
Igneous2. Magma can form
a) Intrusive igneous rocks Small pebbles to huge batholiths
Growing Lava Dome
Crater Lake; Caldera with Lava Dome
Cascades Lava Plateau
Lava Plateau: Like a flood that becomes solid rock
Remains of ancient magma (intrusive)
Hot springs and Geysers
1. Water reacts with nearby magma to form
a)Hot springs: hot water under normal pressure
b)Geysers: hot water that erupts under high pressure
2. Why might people think this water has medicinal properties?
a)Hot water holds a lot of minerals
Edge of Pyroclastic Flow