Which type of rock is formed from the cooling of lava or accumulation of pyroclastic material?

• A. Metamorphic Rocks
• B. Intrusive Rocks
• C. Extrusive Rocks
• D. Sedimentary Rocks

Answer: (C)

The formation of extrusive rocks occurs when lava cools on the Earth's surface or when pyroclastic materials accumulate from explosive volcanic eruptions. When lava erupts from a volcano, it can cool quickly upon contact with the atmosphere or water, leading to the formation of glassy or fine-grained textures typical of extrusive rocks. Additionally, materials ejected during volcanic eruptions, such as ash and pumice, can settle and consolidate, creating layers of pyroclastic deposits. Hence, extrusive rocks are commonly associated with volcanic activity, distinguishing them from other rock types formed through different processes.

In contrast, metamorphic rocks are produced from the alteration of existing rock types under heat and pressure, without melting. Intrusive rocks form when magma cools slowly beneath the Earth's surface, resulting in a coarse-grained texture. Sedimentary rocks arise from the accumulation and compaction of mineral and organic particles over time, typically in water or on surfaces. Hence, the characteristics and formation processes of extrusive rocks clearly define them as the correct answer to this question.