SOC 2070 Lecture Notes - Lecture 4: Pyroclastic Rock, Magma Chamber, Cinder Cone
7 Dec 2016
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Volcanoes: most volcanoes are located near plate boundaries, (cid:1006)/(cid:1007) of all vol(cid:272)a(cid:374)oes are fou(cid:374)d o(cid:374) the (cid:858) i(cid:374)g of fire(cid:859) surrou(cid:374)di(cid:374)g the pa(cid:272)ifi(cid:272) o(cid:272)ea(cid:374), subduction zones and mid-ocean ridges allow molten rock to reach the surface. It is found deep within the crust and upper mantle. It is found flowing from erupting volcano: esse(cid:374)tially, lava is (cid:373)ag(cid:373)a o(cid:374) the earth(cid:859)s surfa(cid:272)e. Magma: the most abundant elements in magma are silicon and oxygen; when combined they are referred to as silica, volcanic rocks are named based on the amount of silica present, types of volcanic rocks: Basalt, andesite, dacite, rhyolite low silica high silica. Viscosity: magma also contains small amounts of gases (water vapour and carbon dioxide), volcanoes have different shapes based on the chemistry and viscosity of their magma, magma viscosity is determined by silica content and temperature. Cooler, more viscous, more gases: magma with low silica content:
