what are composite volcanoes made of quizlet
Composite Volcano. A composite volcano forms in subduction zones when a crustal plate is forced into the mantle and begins to melt. Andesite, dacite and rhyolite lavas are the primary types of lava that form these volcanoes.Eruptions on the volcanoes often alternate between tephra and lava flows. Subduction zone volcanoes.Geologists often use the term stratovolcanoes to describe the mountains that form in subduction zones.he melting oceanic crust forms pools of molten rock in a magma chamber. The magma, molten rock, in the magma chamber is lighter than the volcano rocks that surround it. The magma works its way to the summit where it erupts as tephra or in thick lava flows. Lava eruptions on stratovolcanoes.