What is the molten rock called when it is beneath the Earth’s surface?

The substance known as molten rock that exists beneath the Earth's surface is referred to as magma. This substance is formed from the intense heat and pressure present deep within the Earth, causing the rock to melt. Magma can contain various minerals, gases, and crystals and is critical in the geological processes that lead to volcanic activity when it rises to the surface.

Lava, on the other hand, is the term used for molten rock once it erupts onto the Earth's surface. Basalt and obsidian are types of igneous rocks that can be formed from cooled magma and lava, but they are not molten rocks themselves. Therefore, understanding the distinction between these terms is essential to grasp the processes involved in geology and volcanology.