India has six physical divisions: the Himalayas, the northern plains, the peninsular plateau, the Thar desert, the coastal plains and the islands. The Himalayas run about 2,400 km and are the youngest fold mountains.
The peninsular plateau is the oldest landmass, and the Deccan trap region is formed of basalt from ancient volcanic activity. The Western Ghats are continuous and higher; the Eastern Ghats are broken by river valleys.
The eastern coastal plains are wider and hold the deltas of the Mahanadi, Godavari, Krishna and Kaveri, while the narrow western coast has estuaries and lagoons.