What Is Magma From A Volcano?

Magma is molten rock. It is so hot that the rock has melted to become a thick and sticky liquid. Magma is lighter than the harder rock around it and it tends to rise up towards the crust. Sometimes it collects in large pools called magma chambers. If the Earth's crust is weak above a magma chamber, the magma can burst through the surface and then flow out as lava.

The classic picture of a volcano erupting shows a mountain spewing out fire and ash from its top. This is what happens in a lot of eruptions. Magma builds up in the chimney of the volcano and mixes with gas that comes out of the melted rock. The gas in the mixture makes it light and it rises to the top of the chimney. It then explodes from the cone of the volcano because of the build up of pressure.