Which type of igneous rock cools and solidifies beneath the Earth's surface?

• A. Extrusive Rock
• B. Volcanic Rock
• C. Intrusive Rock
• D. Metamorphic Rock

Answer: (C)

The type of igneous rock that cools and solidifies beneath the Earth's surface is referred to as intrusive rock. This occurs because intrusive rocks form from magma that rises from the mantle and solidifies before it reaches the surface, allowing for a slower cooling process. This slow cooling allows crystals to grow larger, resulting in the coarse-grained texture characteristic of intrusive igneous rocks, such as granite and diorite.

In contrast, extrusive rocks, also known as volcanic rocks, form when magma erupts onto the surface as lava and cools quickly, resulting in smaller crystals and a finer-grained texture. Metamorphic rocks are formed through the alteration of existing rock types due to pressure, temperature, and chemical processes, rather than through the solidification of molten material. Thus, understanding the processes of cooling and solidification is key to identifying the correct classification of igneous rocks.