Define mantle plume and explain its role in plate tectonics.

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.