Igneous rocks form as a result of what process?

Igneous rocks form as a result of melting and cooling, which characterizes their unique formation process. These rocks originate from molten material known as magma beneath the Earth's surface. When magma rises and cools, it solidifies into igneous rock. This process can occur in two primary environments: intrusive (or plutonic) igneous rocks form when magma cools slowly beneath the Earth's crust, allowing for the growth of larger crystals; whereas extrusive (or volcanic) igneous rocks form when magma erupts onto the surface as lava and cools quickly, resulting in smaller crystals or a glassy texture.

Understanding that igneous rocks are linked to the melting of pre-existing rock (whether it be sedimentary, metamorphic, or other igneous material) helps highlight the dynamic processes involved in the rock cycle. The pairing of melting and subsequent cooling is central to the formation of these rocks, distinguishing their origin from other rock types formed by different geological processes.