Download 6.1 * Volcanoes and Plate Tectonics

6.1 – Volcanoes and Plate Tectonics
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Essential Question:
1.
Where Are Volcanoes Found on Earth’s Surface?
Volcanoes, Magma, and Lava
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A volcano is a mountain that forms in Earth’s crust
when molten material (magma) reaches the surface.
Mt. Fuji
Japan
Volcanoes, Magma, and Lava
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
Magma is a mixture rock-forming substances, gases,
and water from the mantle.
When magma reaches the surface it is called lava.
 Magma
and lava both harden to become igneous rocks.
Where Do Volcanoes Form?
Where Do Volcanoes Form?

Volcanic belts form along the boundaries of Earth’s
plates.
Divergent Boundary Volcanism
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When two plates separate magma pours through
the fissure and crates volcanic mountains.
Convergent Boundary Volcanism
1.
2.
3.
4.
The denser plate subducts beneath the less dense one.
As the denser plate subducts into the mantle it melts.
Trapped water lower the melting points of the crust
above.
This hot, less dense, material rises and crates new
volcanoes. (Island arcs and volcanic chains)
Convergent Boundary Volcanism
Convergent Boundary Volcanism
The Ring of Fire

The Ring of Fire is one major belt of volcanoes
located around the rim of the Pacific Ocean.
 Nearly
the entire Pacific Plate is subducting.
The Ring of Fire
Hot Spots
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A hot spot is an area in the mantle that is
particularly hot. (It’s a hot spot!)
Volcanoes can form above a hot spot if the molten
material reaches the surface.
The Hawaiian Islands were formed by a hot spot.
Hot Spots
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The Hawaiian Island chain.