EARTHSS 1 Chapter Notes - Chapter 6: Igneous Rock, Magma Chamber, Continental Crust
24 Oct 2018
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Document Summary
Volcano - a vent from which a combination of melted rock, solid rock debris, and gas is erupted. Pressure increases with depth and that makes more heat - increasing pressure causes rock to resist melting. Characterized by a range of compositions (silica is predominant) Most common magma are called silicate magmas. Three distinct magma compositions most commonly found. Basaltic magma - 50 silica and little dissolved gas and 80 % of all magma is basaltic. Andesitic magma has 60 percent silica and a lot of gas. Rhyolitic magma has 70 percent silica and the highest gas content. Properties of a liquid - can flow - but is made of solids and glasses. Small amounts of gas are called volcanic glasses - principal volcanic gas is water vapor and carbon dioxide - all important for atmosphere. Temp influences properties of magmas and viscosity - higher temp the lower the viscosity and the more readily it flows.
