Correct Option
The correct option is 1 only
Explanation
Volcanic landforms are broadly classified into extrusive and intrusive forms based on the location of solidification. Intrusive landforms are created when magma rises from the mantle but cools and solidifies within the crust before reaching the surface.
Statement-wise Analysis
- Statement 1 is Correct: Intrusive forms are developed when molten material (magma) cools within the crustal portions. While technically termed "magma" when underground, standard geography texts describe this process as "the lava that cools within the crustal portions assumes different forms."
- Statement 2 is Incorrect: Batholiths are large, deep-seated bodies of magmatic material (granitic bodies). While they form at great depths, they do appear on the surface after denudational processes (erosion and weathering) remove the overlying rock layers over geological time. They often form the core of large mountain systems.
- Statement 3 is Incorrect: Dykes are formed when magma solidifies in fissures or cracks perpendicular (vertical) to the ground, creating wall-like structures. The horizontal bodies of intrusive igneous rocks are known as Sills or Sheets.
Key Takeaway: Dykes are vertical or near-vertical intrusive formations, whereas Sills are horizontal. Batholiths are massive, deep-seated plutonic bodies that can be exposed on the surface through long-term erosion.