Short note: Mountain system

A mountain system is a group of mountain ranges related in origin, age and structure, forming a long belt, for example the Alpine-Himalayan system.

Fold mountains

• Formed when sediments deposited in a long, sinking basin (geosyncline) are compressed by plate collision, causing them to fold, fault and rise.
• Characterised by long, narrow belts of folds (anticlines and synclines), thrust faults, metamorphism and igneous intrusions.
• Young fold mountains: Himalaya, Alps, Andes, Rockies. Old ones: Appalachians, Aravalli.

   /\    /\    /\      anticlines
  /  \  /  \  /  \
 /    \/    \/    \    synclines

Importance

• They contain the source areas of major rivers, mineral deposits and hydropower sites.
• They are tectonically active, with earthquakes and landslides, so they need careful engineering geological study.