Be able to define different types of extrusive and intrusive igneous bodies like cinder cones, lava flows, dikes, sills, laccoliths.
Rocks are aggregates of minerals.
We will first look at the origin of igneous rocks. The temperatures of most magmas are between 1200 and 600 degrees celcius. As magma cools, minerals begin to crystalize from the liquid. Its kind of a viscous slushy. Melting may occur in upper mantle because water and sediment introduced by the subducting slab causes partial melting of the upper mantle.