Explanation:
Block mountains are formed when large areas or blocks of the Earth's crust are uplifted or lowered due to tensional forces (pulling apart of the crust). These forces cause faults, and as a result:
- Some blocks are raised to form mountains (horsts),
- Others sink to form valleys (grabens).
Examples: The Vosges Mountains in France and the Sierra Nevada in the USA.
Why other options are incorrect:
- (B) Laccolith mountain – Formed by the intrusion of magma between layers of rock, creating a dome-like structure.
- (C) Old folded mountain – Formed by compressional forces, not tension. They are older and more eroded (e.g., Aravalli Range).
- (D) Young folded mountain – Also formed by compressional forces (e.g., Himalayas, Alps).
Hence, mountains formed due to tensional forces are called Block Mountains.
Explanation by: Mr. Dubey
Block mountains are formed when large areas or blocks of the Earth's crust are uplifted or lowered due to tensional forces (pulling apart of the crust). These forces cause faults, and as a result:
- Some blocks are raised to form mountains (horsts),
- Others sink to form valleys (grabens).
Examples: The Vosges Mountains in France and the Sierra Nevada in the USA.
Why other options are incorrect:
- (B) Laccolith mountain – Formed by the intrusion of magma between layers of rock, creating a dome-like structure.
- (C) Old folded mountain – Formed by compressional forces, not tension. They are older and more eroded (e.g., Aravalli Range).
- (D) Young folded mountain – Also formed by compressional forces (e.g., Himalayas, Alps).
Hence, mountains formed due to tensional forces are called Block Mountains.