Solidification of Molten Magma at Earth's Surface

When molten magma, which is found beneath the Earth's surface, erupts onto the surface, it is called lava. The process of this lava cooling down and hardening is known as solidification. This process leads to the formation of specific types of rocks.

Formation of Basalt and Traps

The solidification of molten magma (lava) at the Earth's surface results in the formation of extrusive igneous rocks. These rocks cool relatively quickly, which leads to the formation of fine-grained textures.

• Basalt is a common type of extrusive igneous rock that forms from lava flows cooling rapidly on the Earth's surface. It is typically dark-colored and fine-grained.
• Traps, such as the Deccan Traps in India, are vast layers of solidified basalt lava flows that cover large areas of the Earth's surface. They are formed by extensive volcanic activity where large volumes of basaltic lava erupt and spread out.

Therefore, option 2 correctly identifies rocks formed from the solidification of magma at the surface.

Understanding Other Rock Types

Let's look at why the other options are not correct:

• Sedimentary Rock: These rocks are formed from the accumulation, compaction, and cementation of sediments (like sand, silt, and clay) or from organic matter. They are not directly formed from the solidification of molten magma.
• Granite: Granite is an intrusive igneous rock. It forms when molten magma solidifies beneath the Earth's surface, allowing it to cool slowly. This slow cooling allows large crystals to form, giving granite a coarse-grained texture.
• Metamorphic Rocks: These rocks are formed when existing rocks (igneous, sedimentary, or even other metamorphic rocks) are changed by heat, pressure, or chemical reactions, typically deep within the Earth. They are not formed by the direct solidification of magma at the surface.