Lecture16 - Volcanism Volcanism is the process by which...

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Volcanism Volcanism is the process by which material is expelled from the interior of a planet Eruptions bring new rock materials to surface ¾ Esp. basalt Volcanic structures: ¾ Cinder cone : conical hill built up around a vent ejecting cinders, ash and boulders ¾ Shield volcano : Gently sloping volcanic mountain, built by fluid lava flow ¾ Composite volcano: Large volcanic mountain with irregular profile, built by eruption of viscous and fluid lavas ¾ Caldera: volcanic crater, caused primarily by collapse ¾ Diatreme: volcanic crater caused primarily by eruptive, explosive activity Caused because magma is slightly less dense than the surrounding rock (upper mantle) ¾ A magma chamber connected by a thin crack to the surface is overpressurized by the surrounding rock
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Faults ¾ Thrust faults and strike-slip faults are due to compression ¾ Normal faults and grabens are due to stretching (rift zones) Mare ¾ Lava-covered plains ¾ Dark colour is due to basic rock Wrinkle-ridge ¾ Usually found in mare (not recognized on earth) ¾ compressional ridges formed during final stages of lava filling? Rilles
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This note was uploaded on 04/15/2009 for the course PHYS 275 taught by Professor Harris during the Winter '09 term at Waterloo.

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Lecture16 - Volcanism Volcanism is the process by which...

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