EOSC 114 Study Guide - Final Guide: Abbotsford, British Columbia, Interferometric Synthetic-Aperture Radar, Tephra
13 Apr 2017
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Magma: created by melting pre-existing rock below the earth"s surface (melt + crystals + bubbles) Lava: melted rock exposed at the earth"s surface (melt + crystals + bubbles) Source region: mantle (made of high density peridotite rock dominantly) Physical properties of magma: density magma is less dense than the mantle and crust (rises out from it, viscosity controls flow and eruption style, depends on temperature, gas/crystal content, silica (sio 2 ) content. Felsic igneous rock: high silica content, light colour, high viscosity e. g. granite, rhyolite. Mafic igneous rocks (what the ocean crust is made up of): low silica content, dark colour, low viscosity e. g. basalt, gabbro: temperature. Note: in cool magma, there are more crystals: gas content: volatiles (dissolved gas: h 2 o, co 2 so 2 ) Velocity is not a physical property of magma. When magma gets to the surface, it could be lava; if it erupts explosively, it is pyroclastic material (hot rock).
