GWBN+3.2

toc = = To go back to the Teamforce Homepage, click here To go back to the GWBN Homepage, click here =Vocabulary=


 * magma chamber-** a pocket in which magma collects


 * pipe-** a long tube in the ground that connects the magma chamber to the Earth's surface


 * vent-** an opening where molten rock and gas leave


 * lava flow-** an area covered by lava as it pours out of a vent


 * crater-** a bowl shaped area that may form at the top of a volcano around the volcano's central vent


 * Silica-** a material that is formed from elements oxygen and silicon


 * Pahoehoe-** fast moving, hot lava


 * aa-** cooler, slower moving lava


 * pyroclastic flow-** occurs when explosive eruption hurls out ash, cinders, bombs and gases


 * active-** the term for a live volcano, having the ability to erupt in the near future


 * dormant-** a 'sleeping' volcano, opposite of active, may be able to erupt in the future


 * extinct**- a dead volcano, which is unlikely to erupt again


 * hot spring-** formed when groundwater heated by nearby body of magma rises to the surface and collects in a natural pool


 * geothermal energy-** water heated by magma produces this clean energy

=Outline=

T= Volcanic Activity
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 * ==How Magma Reaches Earth's Surface==
 * lava begins as magma
 * magma forms in asthenosphere
 * materials of asthenosphere under great pressure
 * ===Magma Rises===
 * liquid magma is less dense than surrounding solid material, it flow upward into cracks
 * magma floats up until trapped or reaches the surface
 * ===A Volcano Erupts===
 * dissolved gases trapped in magma under tremendous pressure
 * as magma rises toward the surface, pressure decreases
 * volcano erupts when opening develops in weak rock
 * once magma reaches surface, becomes lava and gases bubble out
 * ==Inside a Volcano==
 * beneath a volcano, magma collects in magma chamber
 * magma moves through a pipe
 * molten rock and gases leave the volcano through a vent
 * ==Characteristics of the Magma==
 * the force of a volcanic eruption depends on
 * gas content of magma
 * thickness of magma
 * how much silica the magma contains
 * ==Types of Volcanic Eruptions==
 * The silica content in magma helps determine whether the eruption is quiet or explosive
 * ===Quiet Eruptions===
 * a volcano erupts if the magma flows easily
 * Quiet Eruptions produce two eruptions=
 * Pahoehoe
 * fast moving, hot lava
 * surface of lava looks like rope- like coils
 * aa
 * when hardens, it forms a rough, jagged chunks of lava
 * ===Explosive Eruptions===
 * If thick and sticky, the magma will erupt explosively
 * the pressure will build until it explodes
 * hurtles out=
 * bombs
 * fine sand grains
 * pyroclastic flow