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 :
Oceanic-Oceanic/Suducting Graphic taken from: -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: 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 _NAV2-77_SWK953,00.htmlhttp:// 950_NAV2-77_SWK953,00.html