EOSC 114 Lecture Notes - Lecture 4: Peridotite, Cascadia Subduction Zone, Andesite
12 Sep 2016
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Document Summary
Key process in the development and ongoing evolution of our planet. 2/3 of earths crust entirely igneous (oceanic crust) Continental crustal rock is predominantly igneous (and metamorphosed igneous rocks) Igneous rock is formed through the cooling and solidification of magma or lava. Igneous rocks are formed when magma (or molten rocks) have cooled down and solidified. (inside earth"s crust/mantle) Sedimentary rocks are formed by the accumulation of other eroded substances. (in water bodies; seas, oceans) Metamorphic rocks are formed when rocks change their original shape and form due to intense heat or pressure. (on earth"s surface) Extrusive (volcanic) formed outside volcano (exit; on surface) Large crystals = slow cooling (due to insulation) resulting in longer time to grow. Volcanoes form where magma and gas leak out from the earth"s crust and mantle. Magma created by melting pre-existing rock below the earth"s surface, reaches the surface through fractures and extrudes as lava or explodes as pyroclastic material (broken bits of lava).
