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Volcanoes
A Lesson Plan Written By
Tom Huettl
Lecture Outline
» Areas of Volcanism
» Types of Volcanoes
» Types of Lava
» Viscosity
Lecture Outline
» Areas of Volcanism
» Types of Volcanoes
» Types of Lava
» Viscosity
Areas of Volcanism
Sub-ducting Boundaries• Plate Sub-ducts below surface into mantle
•
Oceanic-Oceanic• Volcanoes form near boundary
•
Mid Ocean Ridges• Eruptions occur where plates are diverging
•
Cont.-Cont/ Subducting
Graphic taken from
: http://147.205.15.81/geology/work/VFT-so-far/orogeny/pl.tect.html
Oceanic-Oceanic/Suducting
Graphic taken from:
http://147.205.15.81/geology/work/VFT-so -far/orogeny/pl.tect.html
Mid Ocean Ridges
Areas of Volcanism
– Hot Spots
• Hot Spots remain stationary while plates move above
•
Hot Spots
Graphic taken from:
http://volcano.und.nodak.edu/vwdocs/vw/lessons/atg.htm
l
Types of Volcanoes
– Shield Cone• Has a low rounded profile
• Gentle slopes of 2-10 degrees
•
– Composite Volcano (Strato Volcano)• Both pyroclastic layers and lava flows
• Steep sided near summit with decreasing slope
•
Types of Volcanoes
• Cinder Cone– Pyroclastic Material (Fragmented material that has been
explosively ejected)
– Ash and debris accumulates around the vent
– Small steep sided cones
–
Shield Cone
Composite Cone/Stratovolcano
Cinder Cone
Types of Lava
• Mafic» Silica Poor (45-52%)
• Intermediate» Silica Composition (53-65%)
• Felsic» Contains more than 65% Silica
– High Viscosity
» Slow Flow
» High Silica Content
»
– Low Viscosity
» Fast Flow
» Low Silica Content
»
UMD
For More Information Visit One of The Following Links
The Web's Premiere Source For Volcanoes
U.S. Geological Survey, Volcano Hazards Program
Electronic Resources
• http://147.205.15.81/geology/work/VFT-so-far/orogeny/pl.tect.html
• http://volocano.und.nodak.edu/vwdocs/vwlessons/atg.html
• http://www.studyworksonline.com/cda/content/worksheet/0,1036,EXP950_NAV2-77_SWK953,00.html
• http://observe.ivv.nasa/earth/tectonics/Tectonics.html
• http://members.aol.com/waponi/sound.htm
• http://www.bftr.com/Pages/projects/dante.html
• http://volcanoes.usgs.gov/
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