Volcanoes I. Molten rock

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Volcanoes

I.

Molten rock a.

Magma - beneath the Earth’s surface b.

Lava - magma that extrudes onto the surface of the Earth i.

Pahoehoe - (pa-hoy-hoy)- freely flowing lava that forms a thin skin with wrinkles and then looks like twisted rope when solid ii.

Aa - (ah-ah)- rough, jagged surface with dangerously sharp edges

II.

Different types of Cones a.

Shield Volcanoes -built by a steady supply of very fluid basaltic lava.

Have a broad, gently sloping cone that resembles a shield. i.

Mauna Loa in Hawaii- largest volcano on earth b.

Cinder Cones -very steep, but not high, formed from explosive eruptions from a single vent. i.

Sunset Crater- Arizona ii.

Paricutin- Mexico c.

Composite Cone - (Stratovolcano) erupts both lava and ash with a steep summit and gently sloping sides i.

Erupts explosively ii.

Mt. Vesuvius, Mount Pele Mnt. St Helens, Mt. Pinatubo

III.

Craters - formed at the central vent of an erupting volcano. Increase in size during eruptions i.

Calderas -very large crater > 5km in diameter

1.

Yellowstone National Park- a.

Remnant of a volcano that erupted 600,000 yrs ago. i.

Hot springs, bubbling mud, steaming pools, geysers

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