GEOLOGY 105 Study Guide - Final Guide: Cascade Range, Remote Sensing, Geochemistry
11 Aug 2016
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Magmas and volcanoes: be familiar with the major magma types (basalt, rhyolite etc) Rhyolite and dacite eruptions tend to be more explosive than basalt and andesite eruptions. Most lava flows are basaltic, witht the remainder mostly andesite, with a few dacite and rhyolite flows because the more silica-rich magmas tend to erupt explosively: be familiar with the forms of different volcanoes (shield, fissure etc) A volcano built of alternating layers of cinders and lava. Often referred to as monogenetic volcanoes because unlike stratovolcanoes they usually only erupt once. Made of fluid basalt lava flows, that flow much further, thus giving them their shield-like shape. Most volcanoes occur at converging and spreading margins of plates. Spreading margins: mid-ocean ridges (iceland) & rifting continents (east african. Converging margins: island arcs (aleutians and japan) & continental margins (cascades and andes) Surtseyan- takes place in shallow seas or lakes. Vulcanian- short, violent, relatively small explosion of viscous magma.
