What type of igneous rock forms from lava that cools on the Earth's surface?

What type of igneous rock forms from lava that cools on the Earth's surface?

• A. Intrusive igneous rocks
• B. Metamorphic rocks
• C. Extrusive igneous rocks
• D. Sedimentary rocks

Answer: (C)

The formation of igneous rocks is fundamentally linked to the cooling and solidification of molten rock material, known as magma when below the surface and lava when it reaches the Earth’s surface. Extrusive igneous rocks form specifically from lava that cools quickly after erupting onto the surface. This rapid cooling prevents the formation of large crystals, resulting in a fine-grained texture. Common examples of extrusive igneous rocks include basalt and pumice. In contrast, intrusive igneous rocks, which are formed from magma that cools slowly beneath the Earth's surface, develop larger crystals due to the longer cooling duration. Metamorphic rocks arise from the transformation of existing rocks under pressure and heat, and sedimentary rocks originate from the accumulation of sediment. Thus, extrusive igneous rocks are the correct answer because they specifically result from lava cooling on the Earth's surface.

The formation of igneous rocks is fundamentally linked to the cooling and solidification of molten rock material, known as magma when below the surface and lava when it reaches the Earth’s surface. Extrusive igneous rocks form specifically from lava that cools quickly after erupting onto the surface. This rapid cooling prevents the formation of large crystals, resulting in a fine-grained texture. Common examples of extrusive igneous rocks include basalt and pumice.

In contrast, intrusive igneous rocks, which are formed from magma that cools slowly beneath the Earth's surface, develop larger crystals due to the longer cooling duration. Metamorphic rocks arise from the transformation of existing rocks under pressure and heat, and sedimentary rocks originate from the accumulation of sediment. Thus, extrusive igneous rocks are the correct answer because they specifically result from lava cooling on the Earth's surface.