Molten rock in the Earth is known as MAGMA. MAGMA is a hot, liquid or semi-solid material found beneath the Earth's surface. It is composed of melted minerals and gases and is the source of all igneous rocks. MAGMA is formed when the Earth's mantle melts due to extreme heat and pressure. It can also be formed when existing rocks melt due to the heat of a nearby volcano. MAGMA is an important part of the Earth's geology and plays a role in the formation of mountains, volcanoes, and other landforms.