Which term describes melted rock found beneath the Earth's surface?

Magma is the correct term for melted rock that exists beneath the Earth's surface. It is a molten mixture of various minerals, gases, and other materials and is found in the Earth's mantle and crust. When magma rises to the surface and erupts through a volcano, it is referred to as lava. The distinction is crucial because while both terms involve molten rock, magma is specifically the substance that is underground, while lava is what we see above ground during a volcanic eruption.

Granite and basalt are types of igneous rock that form from the cooling of magma (in the case of granite) or lava (in the case of basalt). Granite typically forms when magma cools slowly beneath the Earth's surface, allowing large crystals to develop. Basalt, on the other hand, is formed from rapidly cooled lava after it erupts and flows on the surface. Thus, the answer focusing on magma as the term for melted rock found below the Earth's surface accurately identifies the specific geological context of the question.