The Western Ghats of India and the central mountains of Madagascar were once part of the same landscape. The very event that split India and Madagascar apart, about 90 million years ago, is what raised both of them.
The Western Ghats of India and the central highlands of Madagascar show a strikingly similar geological profile. They have a similar length from north to south, similar elevation, and geological features that mirror each other on both sides. This is not a coincidence. They were once part of the same landscape, and the same process created both of them.
Up until about 90 million years ago, India and Madagascar were still joined together and moving northeast as one landmass. As they passed over the Marion hotspot, this geological hotspot was pushing extremely hot material from deep inside the Earth towards the surface beneath them. (This hot material is mostly solid rock and not lava. The pressure deep inside the Earth is so high that it stays solid despite the high temperature, and it only starts to melt as it rises towards the upper layers where the pressure drops.)
This intense heat caused the rocks above to expand and rise into a broad dome or bulge. Eventually, the constant heating and stretching weakened the crust so much that it finally broke apart. Geologists call this process rifting. The eastern side of this break became the Western Ghats of India, and the western side became the central mountains of Madagascar.
Key terms
- Hotspot
- A fixed plume of unusually hot material rising from deep in the mantle. As tectonic plates drift over it, it can heat, dome, and crack the crust above.
- Mantle
- The thick layer between Earth's crust and core. Despite being intensely hot, it is mostly solid rock, because the immense pressure keeps it from melting.
- Crustal doming
- When heat from below makes the crust expand and bulge upward into a broad dome, like a blister on the surface.
- Rifting
- The stretching, weakening, and eventual splitting of the crust. Here, it is the break that separated Madagascar from India.
Sources & further reading
Start here — plain language
- K. R. Subrahmanya — “Evolution of the Western Ghats, India: A Simple Model” Beginner-friendly; the paper this reel is based on.
Go deeper — academic
- Storey et al. (1995) — Timing of Hot Spot–Related Volcanism and the Breakup of Madagascar and India
Background reading
Image credits
- Maps and imagery from Wikipedia, or edited by the author.
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