Three Types of Volcanoes

  Shield Volcano Composite Volcano Cinder Cone
Example Mauna Loa Mt. St. Helens; Mt Fuji Paricutin
Rock Type Basalt Andesite Rhyolite
Lava Type Thin;
Low Viscosity		 Thick;
High Viscosity		 Very Thick;
Pyroclastic Flows (Fire Bombs)
Eruption Slow;
Non-violent;
Little ash or projectiles		 Rapid;
Violent;
Large amounts of ash, gas & pyroclastics (Fire Bombs)		 Small;
Localized eruptions; or
Pyroclastics (Fire Bombs)
Frequency Very Frequent for over 1000's of years Recurring eruptions (every 100 years or so) for over as long as one million years Recurring, short lived eruptions for less than 10 years.
Size & Shape Massive Dome shaped mountains Large symmetrical cone Small cone with very steep sides
Features Sea-mounts;
Island chains		 Calderas;
Volcanic plugs;
Nvee ardente;
Lahars		 Composed of individual volcanic lave  fragments, called cinders.


 

Flood Basalts: Composed of basaltic rocks, like Mauna Loa, but occur over continents. The lava is of very low viscosity & spreads out over a large area with successive eruptions layering on top to create large high elevation plateaus. Examples are the "Columbia River Plateau" in the U.S.A. and the "Interior Plateau" of British Columbia

 

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