Question

The texture of rocks formed due to consolidation of magma nearer to the surface is

• A. Course texture
• B. Medium texture
• C. Fine texture
• D. Conglomerate

Hint:

Remember the simple relationship:
Slow cooling = Large crystals = Coarse texture (Intrusive).
Fast cooling = Small crystals = Fine texture (Extrusive).
The closer to the surface, the faster the cooling.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks about the texture of igneous rocks that form from magma cooling near the Earth's surface.

Step 2: Detailed Explanation:
The texture of an igneous rock refers to the size, shape, and arrangement of its mineral crystals.
The most important factor controlling crystal size is the cooling rate of the magma or lava.
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Slow Cooling: When magma cools slowly, deep within the Earth's crust (intrusive or plutonic rocks), the atoms have a long time to migrate and arrange themselves into large, well-formed crystals.
This results in a

coarse-grained texture (also called phaneritic), where individual crystals are visible to the naked eye (e.g., Granite).
-

Rapid Cooling: When magma or lava cools quickly, at or near the Earth's surface (extrusive or volcanic rocks), the atoms have very little time to form large crystals.
This results in a

fine-grained texture (also called aphanitic), where the individual crystals are too small to be seen without a microscope (e.g., Basalt, Rhyolite).
Since the question specifies consolidation "nearer to the surface," this implies rapid cooling.
Conglomerate (D) is a sedimentary rock, not an igneous rock.

Step 3: Final Answer:
Rocks formed from magma cooling near the surface have a fine texture.
This corresponds to option (C).