Volcanoes I. Molten rock

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I.

II.

III.

Volcanoes

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 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 c.

from a single vent. i.

Sunset Crater- Arizona ii.

Paricutin- Mexico

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

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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