Cinder cones - a volcano constructed of loose rock fragments ejected from a central vent. Composite volcano - one constructed of alternating layers of pyroclastics and rock solidified from lava flow with slopes between those of cinder cones and shield volcanoes. Aconcagua , a composite volcano in the Andes, is 6,960 meters above sea level and the highest peak in the western hemisphere. The most viscous lavas form volcanic domes which are rich in silica. They solidify as rhyolite or, less commonly, andesite if minerals crystallize, or as obsidian if no minerals crystallize.
Rhyolitic eruptions are most likely to be explosive .
The material blown out of a volcano is called pyroclastic debris , or tephra . Bubbles that form quickly in a huge mass of sticky rhyolitic magma can shatter into a froth of innumerable tiny glass-walled bubbles, producing a rock called pumice . Vent - opening through which an eruption takes place. Crater - a basinlike depression over a vent at the summit of the cone of a volcano. Flank Eruption - lava pours from a vent on the side of a volcano.