Sketch of a magma reservoir beneath a volcano and a conduit leading up to a lava dome at the surface. Arrow indicates direction of magma movement from a deeper source.
is molten or partially molten rock
beneath the Earth
's surface. When magma erupts onto the surface, it is called lava
. Magma typically consists of a liquid portion (often referred to as the melt), a solid portion made of minerals
that crystallized directly from the melt, solid rocks incorporated into the magma from along the conduit or reservoir, called xenoliths
or inclusions, and dissolved gases.