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