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Volcanoe s Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.
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Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Dec 14, 2015

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Page 1: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Volcanoes

Volcanoes & Plate Tectonics

6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Page 2: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

What is a Volcano?

• A volcano is a weak spot in the crust where molten material, or magma, comes to the surface.

• Magma is a molten mixture of rock-forming substances, gases, and water from the mantle.

• When magma reaches the surface, it is called lava.

Page 3: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Location of Volcanoes

• There are about 600 active volcanoes on land.

• Many more are found beneath oceans

• Most occur in belts that extend across continents and oceans

Page 4: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

• A major belt is the “Ring of Fire” which encircles the Pacific Ocean

Page 5: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Most volcanoes occur along diverging plate boundaries such as the mid-ocean ridge, or in subduction zones, around edges of oceans

Volcanic belts form along the boundaries of Earth’s plates.

Page 6: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Volcanoes often form where two or oceanic plates collide or where an oceanic plate collides with a continental plate. In both situations, an oceanic plate sinks beneath a trench. Rock above the plate melts to form magma, which then erupts to the surface as lava.

Page 7: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.
Page 8: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

• “Hot Spot” volcanoes form where magma from deep within the mantle melts through the crust like a blow torch

• Examples:– Hawaiian Islands– Yellowstone National Park

Page 9: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.
Page 10: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Inside a Volcano

• All volcanoes have a pocket of magma beneath the surface and one or more cracks through which magma forces its way through

• Magma pocket is called a magma chambermagma chamber

• A pipepipe is a long tube in the ground that connects the magma chamber to the earth’s surface

Page 11: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

• Molten rock and gas leave the volcano through an opening called a ventvent

• A lava flowlava flow is the area covered by lava as it pours out of a vent

• A cratercrater is a bowl-shaped area that may form at the top of a volcano around the central vent

Page 12: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.
Page 13: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

A Volcanic Eruption

• When a volcano erupts, the force of the expanding gases pushes magma from the magma chamber through the pipe until it flows or explodes out of the vent.

• Once magma escapes from the volcano and becomes lava, the remaining gases bubble out.

Page 14: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Types of Volcanic Eruptions

• Geologists classify volcanic eruptions as quiet or explosive.

• The silica content of magma helps to determine whether the volcanic eruption is quiet or explosive

• Silica is the material formed from the elements silicon and oxygen

Page 15: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

• Silica is one of the most abundant materials in Earth’s crust and mantle

• The more silica that magma contains, the thicker it is

Page 16: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Quiet Eruptions:

• A volcano erupts quietly if its magma is low in silica.

• Magma flows easily; the gas dissolved in the magma bubbles out gently

• Examples:

– Hawaii– Iceland

Page 17: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Quiet eruptions produce two types of lava:

1. Pahoehoe1. Pahoehoe - fast moving, hot lava;

Surface looks like a solid mass of wrinkles, billows, and rope-like coils.

2. Aa2. Aa - cooler, slower-moving lava; when hardens, forms a rough surface consisting of jagged lava chunks.

Page 18: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Explosive Eruptions:

• A volcano erupts explosively if its magma is high in silica.

• Magma is thick and sticky• Magma slowly builds up in the

volcanoes’ pipe • Dissolved gases cannot escape• Trapped gasses build up pressure until

they explode

Page 19: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

• A pyroclastic flowpyroclastic flow occurs when an explosive eruption hurls out ash, cinder, bombs, and gasses

• Pebble-sized particles are called cinders.

• Larger pieces, called bombs, may range from the size of a baseball to the size of a car.

Page 20: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Stages of a Volcano

• ActiveActive - is erupting, or has shown signs that it may erupt in the near future

• DormantDormant - does not show signs of erupting in the neat future

• ExtinctExtinct - unlikely to erupt

Page 21: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Related Volcanic Activities

• Hot SpringHot Spring - groundwater heated by a nearby body of magma rises to the surface and collects in a natural pool

Page 22: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.
Page 23: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

• GeyserGeyser - forms when rising hot water and steam become trapped underground in a narrow crack

• Pressure builds until the mixture suddenly sprays upward, clearing the crack

Page 24: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.
Page 25: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Volcanoes

Volcanic Landforms

Page 26: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Types of Volcanoes

• Shield VolcanoShield Volcano: nonexplosive eruptions, fluid basaltic lava, gentle broad slopes

– Thin layers of lava pour out of a vent and harden on top of previous layers

– Example: Hawaiian Islands

Page 27: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Shield VolcanoShield Volcano

Page 28: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

• Cinder Cone VolcanoCinder Cone Volcano: explosive eruptions, small but steep slopes, pyroclastics

– Form when cinders from a vent, pile up around the vent, forming a steep- cone-shaped mountain

Page 29: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Cinder Cone VolcanoCinder Cone Volcano

Page 30: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

• Composite VolcanoComposite Volcano: alternating between lava and pyroclastics, explosive and nonexplosive eruptions, steep and tall

– Layers of lava alternate with layers of ash, cinders, and bombs

Page 31: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Composite VolcanoComposite Volcano

Page 32: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Related Volcanic Landforms

• CalderaCaldera:

– A large hole at the top of a volcano formed when the roof of a volcano’s magma chamber collapses

Page 33: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Formation of a Caldera

Page 34: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

• DikeDike:

– A slab of volcanic rock formed when magma forces itself across rock layers

– (vertical rock formation)

Page 35: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

DikeDike

Page 36: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

• SillSill:

• A slab of volcanic rock formed when magma squeezes between layers of rock

• (horizontal rock formation)

Page 37: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

SillSill

Page 38: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

• BatholithBatholith:

• A mass of rock formed when a large body of magma cooled inside the crust

Page 39: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

BatholithBatholith

Page 40: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

• Dome MountainsDome Mountains:

– Rising magma within the crust is blocked by layers of rock

– Magma forces layers of rock to bend upward into a dome shape

– Example: Black Hills

Page 41: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Dome MountainsDome Mountains

Page 42: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

Questions

When magma reaches the surface, it is called?

A. Larva

B. Lava

C. Lagoon

D. Lump

Page 43: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

What is a magma pocket called?

A. Magma chamber

B. Hot pocket

C. Hot chamber

D. None of the above

Page 44: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

What type of lava is fast moving?

A. Aa

B. Naa

C. Pahoehoe

D. HoHoHo

Page 45: Volcanoes Volcanoes & Plate Tectonics 6.E.2.2 Explain how heat flow and volcanoes reflect forces within the earth.

The End