EESA06H3 Lecture : EESA06 - Lec 5.doc
Document Summary
Imp: recycling oceanic crust, adding to continental crust. The pacific rim of fire, continents surrounding the rim are growing at the expense of the oceans = long process. Process = subduction, magma is moving up continental crust (e. g. picks up minerals, silicon = makes volcano explosive) Old heavier (dense) will go down, like incubator making island arcs creating embryonic continents (can"t subduct continental crust b/c too heavy) 4 billion years ago = magma ocean (ocean water came out of mantle) Cooling of magma ocean created continents (fig. Large tsunamies = result of massive displacement of sea floor. Merapi volcano = most active volcano in indonesia. Protocontinent = indonesia (b/c of island arcs) Pyroplastic cones = slide slopes of volcano collapse. Lateral blast and best farm land on volcano slopes (dangerous) Lahan = reworking of ash by rain (turn ash into heavy mud) More sulphur released as get closer to an eruption. Avalanche of hot gas and pyroplastic glass.
