Which of the following pairs of mountains are both examples of 'Old Fold Mountains'?

Correct Option

The correct option is

Aravali and Appalachians

Explanation

Fold mountains are formed due to the compressive forces generated by plate tectonics, leading to the folding of crustal rocks. Based on their geological age, they are classified into two categories:

• Young Fold Mountains: Formed during the Tertiary period (recent geological past). They feature high peaks, deep valleys, and rugged relief (e.g., Himalayas, Alps).
• Old Fold Mountains: Formed during the Pre-Tertiary period (ancient geological past). Due to prolonged exposure to denudation (erosion), they have lower elevations and rounded peaks.

Option Analysis

• Himalayas and Alps Himalayas and Alps: Incorrect. Both are examples of Young Fold Mountains. The Himalayas formed due to the collision of the Indian and Eurasian plates, while the Alps formed from the collision of the African and Eurasian plates.
• Aravali and Appalachians Aravali and Appalachians: Correct. Both are examples of Old Fold Mountains.
  • The Aravali Range in India is one of the oldest fold mountain systems in the world, dating back to the Pre-Cambrian era. It is now a relict mountain range due to extensive erosion.
  • The Appalachians in North America were formed during the Paleozoic era and are significantly worn down compared to younger ranges like the Rockies.
• Andes and Rockies Andes and Rockies: Incorrect. Both are Young Fold Mountains. The Andes (South America) and the Rockies (North America) are part of the geologically active Circum-Pacific Belt.
• Vosges and Rhine Vosges and Rhine: Incorrect. The Vosges mountains (France) are examples of Block Mountains (Horsts), formed by faulting rather than folding. The Rhine flows through a Rift Valley (Graben) located between the Vosges and the Black Forest mountains.

Key Takeaway

Old Fold Mountains (e.g., Aravalis, Appalachians, Urals) are characterized by low elevation and rounded peaks due to millions of years of erosion, whereas Young Fold Mountains (e.g., Himalayas, Alps, Andes) are lofty with sharp peaks and active tectonics.