volcanoes mind map

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  • Created by: elizabeth
  • Created on: 20-03-14 11:21
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  • VOLCANOES
    • features of plate margins
      • constructive (divergent) margins
        • oceanic ridges
          • mid atlantic ridge (slow rate)
        • rift valleys
      • destructive (convergent) margins
        • oceanic/continental convergence
      • conservative margins
        • when 2 crustal plates slide past each other. there is no volcanic activity
        • san Francisco 1906+1989 LA 1994- margin San Andres Fault where the pacific and American plate are parallel to each other
      • hot spots
    • distribution of volcanoes
      • hot spots
        • middle of pacific-Hawaiin islands
      • on/near subduction zones
        • ring of fire line of volcanoes that surround the pacific
      • rift valleys
        • African rift valley inc mt Kenya+Kila manjaro
      • along oceanic ridges plates moving apart
        • mid altlantic ridge and Iceland
    • volcanic eruptions
      • intrusive volcanic landforms
        • when magma is forced to the surface only a small amount of the mass reach that level. Most of the magma is intruded into the crust where it solidifies
        • batholiths
          • formed deep below the surface when large masses of magma cool and solidify. as the magma cools slowly large crystals are formed in the rock, they are domed shaped and exposed by erosion
            • eg granite, Dartmoor and isle of arran
        • laccolith
        • metamorphic aurole
          • the area surrounding the batholith is altered by heat and pressure of the intrusion to form a metamorphic aurole
            • limestone can be transformed into marble
        • dykes
          • vertical intrusions with horizontal cooling cracks. they cut across the bedding planes of the rocks in which they have been intruded
            • many Scottish islands such as mull and skye have clusters or swarms of dykes
        • sills
          • horizontal intrusions along the bedding planes. Sills have vertical cooling cracks
            • great whin sill and drumadoon isle of arran
      • extrusive volcanic landforms
        • 2 forms of lava
          • basaltic lava
          • andesitic and rhyolitic
        • lava plateaux
        • basic/shield
        • acid/dome
        • ash/cinder
        • composite
        • calderas
      • minor volcanic landforms
        • solfatara
          • small volcanic areas without cones, produces by gases (mainly sulphurous) escaping to the surface
            • Bay of Naples Italy
        • geysers
          • when water heated by volcanic activity explode onto the surface
            • old faithful Yellowstone
        • hot springs/boiling mud
          • sometimes the water heated below does not explode onto the surface. If this water mixes with surface deposits boiling mud is formed
            • Common in Iceland and hot springs in Bath UK
    • the impact of volcanic activity
      • secondary effects
        • lahars
          • volcanic mud flows
            • Columbia- Armero follow eruption of Nevado del Ruiz Nov'85
        • flooding
          • melting glaciers
        • tsunamis
          • waves generated following violent caldera forming event
            • Krakatoa 1883 drowned 36,000
        • volcanic landslides
        • climatic change
          • ejection of vast amounts of debris can reduce global temperatures and is believe to have been an agent in past climate change
    • theories of plate tectonics

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