Along the whole length of the western part , at a distance of 80 to 160km from the sea runs the great mountain wall of the Western Ghats , a rugged chain of mountains rising from 1220 metres at the minimum to 2500 metres. The wall breaks for a 25km stretch at Palghat. The heavily forested slopes of this range are the sources of the Kaveri, Vaigai and Tamaraparni Rivers. The 760km long Kaveri River is the lengthiest. On the east are the Pallani Hills , which host Kodaikanal , the famous hill-station.
Agriculture is the mainstay of the state s economy.
Rice output is among the highest in India. The principal plantation crops are tea and coffee.