6 types of volcanoes, fissure volcano, shield volcano, volcanic dome, cinder cone volcano, stratovolcano, caldera volcano game: http://www.purposegames.com/game/types-of-volcano-game Convergent plate boundaries Main article: Convergent boundary Subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. In this case, the oceanic plate subducts, or submerges under the continental plate forming a deep ocean trench just offshore. In a process called flux melting, water released from the subducting plate lowers the melting temperature of the overlying mantle wedge, creating magma. This magma tends to be very viscous due to its high silica content, so often does not reach the surface and cools at depth. When it does reach the surface, a volcano is formed. Typical examples for this kind of volcano are Mount Etna and the volcanoes in the Pacific Ring of Fire. "Hotspots" Main article: Hotspot (geology) "Hotspots" is the name given to volcanic provinces postulated to be formed by mantle plumes. These are postulated to comprise columns of hot material that rise from the core-mantle boundary. They are suggested to be hot, causing large-volume melting, and to be fixed in space. Because the tectonic plates move across them, each volcano becomes dormant after a while and a new volcano is then formed as the plate shifts over the postulated plume. The Hawaiian Islands have been suggested to have been formed in such a manner, as well as the Snake River Plain, with the Yellowstone Caldera being the part of the North American plate currently above the hot spot. This theory is currently under criticism, however.[1] Volcanic features Lakagigar fissure vent in Iceland, source of the major world climate alteration of 1783--84. Skjaldbreiður, a shield volcano whose name means "broad shield" The most common perception of a volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit. This describes just one of many types of volcano, and the features of volcanoes are much more complicated. The structure and behavior of volcanoes depends on a number of factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater, whereas others present landscape features such as massive plateaus. Vents that issue volcanic material (lava, which is what magma is called once it has esc\a vent of an igneous volcano. Fissure vents Main article: Fissure vent Volcanic fissure vents are flat, linear cracks through which lava emerges. Shield volcanoes Main article: Shield volcano Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent. They generally do not explode catastrophically. Since low-viscosity magma is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of uptions of mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 meters high. Most cinder cones erupt only once. Cinder cones may form as flank vents on larger 3. Conduit (pipe) 4. Base 5. Sill 6. Dike 7. Layers of ash emitted by the volcano 8. Flank 9. Layers of lava emitted by the volcano 10. Throat 11. Parasitic cone 12. Lava flow 13. Vent 14. Crater 15. Ash cloud Main article: Stratovolcano Stratovolcanoes or composite volcanoes are tall conical mountains composed of lava flows and other ejecta in alternate layers, the strata that give rise to the name. Stratovolcanoes are also known as composite volcanoes, created from 6 types of volcanoes,volcano,volcanoes,stratovolcano,shield volcano,caldera volcano,composite volcano,volcanic,cinder cone,ash cinder volcano,tephra,rhyolite,dacite,magma,lava,felsic,mafic,fissure volcano,fissure vent,mid ocean ridges,hotspots,subduction zones,island arc,Convergent boundary,Convergent plate boundaries,oceanic plate,continental plate,ocean trench,silica,viscous,Ring of Fire,Mount Etna,mantle plumes,tectonic plates,Iceland

• published: 13 Jan 2014
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