This mountain range runs from north to south almost parallel to the Arabian Sea. The Western Ghats are known by different local names. In Maharashtra and Karnataka they are called Sahyadri. Further south, they are called the Nilgiris in Tamil Nadu.
Still further south along the Kerala and Tamil Nadu border, they are known as Annamalai and Cardomom Hills. The Deccan Plateau is the highest along it western edge and qently slopes towards the Bay of Bengal in the east. The Western Ghats are relatively higher in their southern part. The Anai Mudi, the highest peak, is 2,695 metres above the sea level. Udagamandalam (Ooty) is a well known hill station of the south located in Tamil Nadu.
Unlike the western edge, the eastern limit of the Deccan plateau is less sharp. It is in fact widely broken into small hills by the rivers such as the Mahanadi, Godavari, Krishna and Cauvery. The Eastern Ghats are locally known by different names.
The North-West part of the Deccan Plateau merits special mention. It is made up of igneous rocks of volcanic origin. From the earth’s highly turbulent interior, lava oozed out through huge cracks or fissures in the earth’s crust. It took millions of years and it is estimated that the volume of the lava flow exceeded the volume of the Himalayas.
Geologists! Believe that this activity was closely associated with the birth of the Himalayas. While all the major rivers of the peninsular block flow into the Bay of Bengal, Narmada and Tapti are the only two rivers flowing in the opposite direction to fall in the Arabian Sea.
These long rivers flow through very narrow elongated valleys. The Narmada valley is bounded by the Vindhyas on the north and the Satpuras in the south. To the south of the Satpura lies the Tapti River. These two rivers valleys are said to be old rift valleys. They join the sea through narrow estuaries.
The Deccan lava plateau gives way to Karnataka Plateau of gneiss and granite formations. The general elevation of the plateau varies between 450-800 metres but, in the north, it attains an altitude of upto 1000 metres. The Malnad and the Maidan are two subdivisions of the Karnataka Plateau. The Malnad is thickly forested upland having Baba Budhan as its highest hill. The Maidan is a rolling plateau with low relief.