Extrusive Volcanic Landforms
Refers to AQA A2 Geography (Plate Tectonics and Assosiated Hazards)
- Created by: Bethany
- Created on: 31-03-14 19:32
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- Extrusive Volcanic Landforms
- Involves two forms of lava...
- Basaltic Lava
- Formed by lava low in silica, making for more fluid magma that allows gas bubbles to expand on the way up to the surface.
- Prevents sudden explosive activity.
- Formed by lava low in silica, making for more fluid magma that allows gas bubbles to expand on the way up to the surface.
- Andesetic and Rhyolitic Lavas
- Formed from silica-rich (acid) magma that is very viscous.
- Often solidifies before reaching the surface, leading to a build up of pressure and violent explosion.
- Formed from silica-rich (acid) magma that is very viscous.
- Basaltic Lava
- Lava Plateaux
- Formed by fissure eruptions.
- Extensive lava flows are basaltic, so flows great distances.
- Usually flat and featureless, such as the Antrim Lava Plateaux, Northern Ireland.
- Basic/ Shield Volcanoes
- Formed from free-flowing lava.
- The resulting volcanoes have gentle sides and cover a large area.
- Mauna Loa, Hawaii, is an example.
- Ash and Cinder Cones
- Formed from ash, cinders and volcanic bombs ejected from the crater.
- Steep, symetrical sides.
- Paricutin, Mexico is an example.
- Acid/ Dome Volcanoes
- Steep sided convex cones consisting of viscous lava, probably rhyolite.
- Best examples in the Puy regions of central France.
- Composite Cones
- The classic, pyramid-shaped, volcanoes.
- Consist of layers of ash and lava that are usually andesetic
- Mt. Etna, Sicily, is a good example.
- Calderas
- Occur when the build up of gas becomes extreme and a huge explosion removes the summit of the cone.
- Leaves an opening several kilometres in diameter.
- May be floided by sea, or a lake may form within it.
- Examples include Krakatoa in Indonesia and Santorini in Greece.
- Occur when the build up of gas becomes extreme and a huge explosion removes the summit of the cone.
- Involves two forms of lava...
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