ch 10 volcanoes a.volcano- vent in the earth’s surface that often forms a mountain when layers of...
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Ch 10 Volcanoes
A. Volcano- vent in the Earth’s surface that often forms a mountain when layers of lava & volcanic ash erupt & build up
What causes a Volcano?
Heat & pressure cause rock to melt deep within the Earth
magma is formed
magma is less dense than rock around it & rises
Parts of a Volcano
B. Vent – opening in Earth’s surface that molten rock comes out of
C. Crater – steep walled depression around a volcano’s vent
http://www.brainpop.com/science/earth/volcanoes/index.weml
D. Hot Spots
• Areas where magma from deep in Earth’s mantle has melted through the crust to form several volcanoes
Ex. The Hawaiian Island chain
• the Pacific Plate is moving over a stationary hot spot
• Kauai is the oldest
• Lo’ihi an underwater volcano will form the next island in the chain
E. Caldera
• Formed when the top of a volcano collapses into the partially emptied magma chamber
• Produces a large opening • Ex. Crater Lake in Oregon
VI . Plutons
• igneous rock (intrusion) that cools inside other rock
Types of Plutons
1. Dikes – vertical intrusion that cuts across layers, rock types do not match
2. Batholiths – largest igneous intrusions, forms when magma cools underground before reaching the surface
Types of Plutons
3. Sills – form when magma squeezes into horizontal cracks & hardens
4. Laccolith – domed sill, that has pushed up the rock above it
Stone Mt., Georgia
Types of Plutons
5. Volcanic neck – the hard solid vent of a volcano left behind after the cone erodes
Ex. Ship Rock New Mexico & Devil’s Tower
Mt. Vesuvius, Pompeii, Italy 79 AD
Mt. Vesuvius, Pompeii, Italy 79 AD
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