Why are the world’s fold mountain systems located along the margins of continents? Bring out the association between the global distribution of fold mountains and the earthquakes and volcanoes.

Theme

T26 Earth's interior, plate tectonics, mountains, islands & landforms

What UPSC asks in this theme

UPSC asks the mechanism behind landforms: continental drift, plate tectonics, mantle plumes, why fold mountains lie on continental margins, island arcs (Indonesia, Philippines), fjords, rocks, why India is a subcontinent, and how mountains affect weather.

What to cover

• Earth's interior and evidence (seismic waves, Juno-type missions)
• Continental drift → sea-floor spreading → plate tectonics; mantle plume and hotspots
• Fold mountains, island arcs, fjords, deltas
• Rock types and primary rocks
• India as a subcontinent: physiography, Himalayan barrier
• Mountain alignment and local weather (rain shadow, barrier effect)

Writing the answer

• Draw a quick diagram (plate boundary, plume) — it saves words
• Give world and Indian examples for each landform

These notes are for the whole theme, built from all 10 of its PYQs. UPSC does not publish model answers.