The highest peak in India south of the Himalaya, crowning the Western Ghats.
Anamudi rises to 2,695 m in the Anaimalai and Eravikulam highlands of Kerala, the highest ground anywhere in India south of the Himalaya. It is a broad, grey dome of bare rock standing above rolling montane grassland, the tallest swell in a long wall of hills that runs down the western edge of the peninsula.
Two very different ages meet in this one hill. The rock is old and the height is young, and it helps to take them one at a time.
The rock is charnockite, a hard, dark stone that belongs to a family geologists call granulites. Granulite is what you get when older rock is cooked deep inside the crust, at great heat and crushing pressure, until its minerals recrystallise into a tight, dense, dry mass. Anamudi sits in the Southern Granulite Terrain, a broad region of this deep-crust rock that lies just south of the ancient Dharwar craton, one of the oldest rigid blocks in India. The charnockite here formed in Precambrian time, so long ago that it predates almost all life you could see with the naked eye. Because it is so dense and dry, it wears down slowly, which is a large part of why it now stands high.
The height came much later, and it is tied to the birth of the Western Ghats themselves. India was once locked against Madagascar inside the supercontinent Gondwana. When the two pulled apart, roughly 88 to 90 million years ago, the crust tore along what is now India’s west coast. The shoulder of a rift like this does not sink; it lifts. As the crust stretched and thinned and hot mantle rose beneath it, the land along the new coast was pushed up into a raised rim, and its seaward face was left as a steep drop. That raised, steep-edged rim is the Western Ghats, and Anamudi is its highest point.
The uplift did not stop when the rifting did. As rivers cut into the raised edge and carried the debris out to sea, the crust below, relieved of that weight, floated slowly upward to compensate, the way a boat rides higher when cargo is unloaded. This slow rebound kept renewing the height over tens of millions of years. Erosion stripped away the softer, weaker rock and left the toughest charnockite standing proud, so Anamudi is less a thing that was built up than a hard core that refused to wear away while everything around it did.
Today that height does real work. The Ghats stand square in the path of the southwest monsoon, so moist sea winds are forced up over the high rock, cool as they climb, and drop their rain on the western slopes. That reliable, heavy rainfall feeds the shola-grassland mosaic on Anamudi’s plateaus, a patchwork of dense evergreen woodland in the folds and open grass on the exposed ground, which shelters the largest surviving population of the Nilgiri tahr inside Eravikulam National Park. The old rock chose where the mountain would be, the young uplift gave it height, and the height, catching the monsoon, made it wet enough to hold that living world.
Sources
- Geological Survey of India
- Mechanism of rift flank uplift and escarpment formation evidenced by Western Ghats, India (2019), Scientific Reports
- Crustal structure of the western part of the Southern Granulite Terrain, India (IIT Bombay)