How was magma formed?

1 There are three states of matter commonly found on Earth: solid, liquid, and gas. When something changes from the solid state to the liquid state, we say it has melted. Ice melts. Chocolate melts. But did you know that rocks can melt, too? 2 Hot, molten rock is called magma. read more

Magma forms when rocks in the mantle melt due to changes in pressure or the addition of water. Although temperatures in the earth's mantle are much hotter than melting temperature, there is not a layer of magma or molten rock under the earth's surface at any given time because there is too much pressure for rock to melt. read more

Rock formed of solidified magma is called igneous rock. While the study of magma has historically relied on observing magma in the form of lava outflows, magma has been encountered in situ three times during geothermal drilling projects—twice in Iceland (see Magma usage for energy production below), and once in Hawaii. read more

As long as more magma pools into a volcano’s magma chamber, there is the possibility of an eruption and the volcano will remain active. Large eruptions can nearly empty the magma chamber. The layers of magma may be documented by the type of eruption material the volcano emits. read more