Geo Sci Final Class Study Guide

Geo Sci Final Class Study Guide - surface where they cool,...

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s tend to be more explosive than basalt and andesite eruptions. Geo Sci Final Class Study Guide Magmas and Volcanoes Major magma types - Basalt o Highest temperatures and lowest Silica content o Low viscosity o Easiest fluid flow o Black to dark grey o “Peaceful” eruptive style o 80% of magma reaching the Earth’s surface is basaltic Andesite o Medium to dark grey o Medium Silica content o Lower viscosity o Mild eruptive style - Dacite - Rhyolite o Lowest temperatures and highest Silica content o HIGH viscosity o Rarely flows o Light-colored o “Explosive” eruptive style o 10% of magma reaching the Earth’s surface is rhyolitic Fundamental differences between magma types - Basaltic magma has the lowest viscosity – more of it reaches the surface
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- Rhyolite is more viscous so they are more sluggish and tend to be trapped deep below the
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Unformatted text preview: surface where they cool, solidify and grow into the larger mineral crystals of plutonic rocks such as granite-In low viscosity basalt magma, steam escapes easily and magma is low in dissolved water content-High viscosity rhyolite magma rises and steam bubbles form they have difficulty escaping from the gooey magma and have to burst their way out How do these characteristics influence eruptions? How are magmas produced in the earths crust and mantle? Forms of difference volcanoes Why do volcanoes have different forms? Types of Lava How do lava types vary from each other? Where do volcanoes occur?...
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This note was uploaded on 03/17/2009 for the course GEO SCI 105 taught by Professor Rhodes during the Spring '06 term at UMass (Amherst).

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Geo Sci Final Class Study Guide - surface where they cool,...

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