Major forms of extrusive activity 0.0 / 5 ? GeographyPlate tectonicsA2/A-levelAQA Created by: LillyCreated on: 20-04-14 16:45 Fissure Volcano Constructive margin Produces basaltic lava Long, linear vent Fairly flat due to low viscosity of lava- flows long distances Eg- Laki Fissure System, Iceland 1 of 6 Basic / Shield Volcano Constructive margin Basaltic lava Gently sloping sides- low viscosity of lava means that it flows long distances Eg- Mauna Loa, Hawaii 2 of 6 Ash and Cinder Cones Formed from ash, cinder and volcanic bombs ejected from crater Steep sided and symetrical 3 of 6 Ash / Dome Volcano Destructive margin Rhyolitic/ andesitic lava Steep sided- high viscosity of lava- flows short distances Convex cones Eg- Puy de Dome, France 4 of 6 Composite Cone Constructive margin Classic pyramid shape Layers of ash/ lava Andesitic lava 5 of 6 Calderas Destructive margin Andesitic / rhyolitic lava Central part of volcano has collapsed due to build up of gases, become so extreme resulting in huge explosion. Very wide, circular crater, can be flooded by the sea. Eg. Krakatoa, Indonesia. 6 of 6
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