GEOL 1001 Study Guide - Midterm Guide: Lapilli, Tuff, Rhyolite
Document Summary
Volcanoes are events at which molten rock (lava), pyroclastic debris, gas, and aerosols erupt at. A hill or mountain created from the products is also called a volcano. The characteristics of a lava flow (molten rock that moves above ground) depend on its viscosity, which in turn depends on its temperature and composition. Andestic and rhyolitic flows tend to pile into mounds at the vent. Pyroclastic debris=molten rock that moves over the ground. Eruptions may occur at a volcanos summit or from fissures on its flanks. The summit of an erupting volcano may collapse to form a bowl shaped depression called a caldera. A volcanos shape depends on depends on the type of eruption: Cinder cones= are steep sided, symmetrical hills composed of tephra. Composite volcanos/stratovolcanoes=can become quite large and consist of pyroclastic debris and lava. Type of eruptions depend on several factors, including the lava"s viscosity and gas content. Explosive eruptions=produce clouds and flows of pyroclastic debris.
