DOST Science Practice Exam

Magmatism is the process that describes the formation of magma and its movement within the Earth. It begins with partial melting of existing rocks in the mantle or lower crust, producing magma with a different composition from surrounding rocks. This magma then begins to rise and move through the crust via magma chambers, conduits, and fractures, driven by buoyancy and pressure. As it travels and eventually cools, it can crystallize to form intrusive igneous rocks or erupt to the surface as lava to form extrusive rocks. This term specifically links both the creation of magma and its transport, setting it apart from surface processes like weathering and erosion, and from metamorphism, which involves mineral changes in rocks due to heat and pressure without melt.