The Narmada rift valley divides the peninsular plateau into two parts. They are the Malwa plateau and the Deccan plateau. The Malwa plateau is bounded by the Aravalli hills in the north-west and the Vindhya Mountains in the south. The total area of both these plateaus is 7,05,000 sq. km. and the shape is triangular. The Malwa plateau slopes towards the Gangetic Plain. The highest peak on the Aravallis is Mt. Guru Shikhar.
The Deccan Plateau is the oldest plateau not only in India but also in the world. The hills of Aravali, Kaimur, Rajmahal, and Shillong make the northern border of the peninsular plateau. Its southern tip is Kanyakumari which touches the Indian Ocean. There are the Eastern Ghats slightly west to the coastal plain on its eastern border. They are in the form of residual mountains which are not regular but broken at intervals. The Western Ghat mountains are situated on the western side of the deccan plateau.
The mountains of the peninsular plateau can be understood in detail by dividing them under the following sub-heads:
(a) The Aravali Mountain Range
It is a residual mountain range. It is one of the oldest fold mountain ranges in the world. The length of the Aravalis is 1100 km which extends from Delhi to Ahmedabad. It is known as ‘Jarga’ near Udaipur and ‘Delhi Ridge’ near Delhi.
Highest Peak : Guru Sikhar. It is on the Abu hills. Mt. Abu is a famous hill station.
(b) The Western Ghat Mountain Range or the Sahyadri Range
The Western Ghat mountain range is India’s second largest mountain range after the Himalayas. Its length is about 1500 km. This range extends from the Tapi river valley to the Nilgiri hills. This range is also known as the Sahyadri range. It is divided into two parts—the North Sahyadri and the South Sahyadri. The 16°N latitude which passes through Goa is the dividing line between them. There is a lava deposition on the upper surface of the northern Sahyadri.
Western Ghats are locally known by different names such as Sahyadri in Maharashtra, Nilgiri hills in
Karnataka and Tamil Nadu and Anaimalai hills and Cardamom hills in Kerala.
The highest peak of the North Sahyadri is ‘Kalsubai’ (1646 m) whereas that of the South Sahyadri is ‘Kudremukh’ (1892 m).
The second highest peak of the South Sahyadri is ‘Pushpagiri’.
Nilgiri hills are a physiographic knot where the Eastern Ghats and the Western Ghats meet together. The highest peak of the Nilgiris is Dodabetta (2623 m) which is the second highest peak of South India.
The highest peak of South India is ‘Anamudi’ (2695 m) peak. Anamudi is a mountain of the Annamalai mountain located in Ernakulam and Idukki districts of the Indian state of Kerala. There are Cardamom hills to the south of the Annamalai mountain and the Nagercoil hill is to the south of the Cardamom hills. To the south of the Annamalai mountain emerges the Palni hill which has north-east direction.
The famous hill station ‘Kodaikanal’ (Tamil Nadu) is on the Patni hill whereas ‘Ooty’ (Udagamandalam or Ootacamund) is located on the Nilgiris in Tamil Nadu. The ‘Gersoppa’ or ‘Jog’ (Mahatma Gandhi) waterfall on Sharavati river is located in the Western Ghats. This is India’s highest waterfall. There are four main passes that have developed in the Western Ghats. Their location from the north to the south is as follows:
1. Thal Ghat
2. Bhor Ghat
3. Pal Ghat
4. Senkota pass
(c) The Eastern Ghat Mountain Range
This mountain range extends from Odisha to Tamil Nadu. It is a residual form of the old fold mountain. It has been more eroded than the Western Ghats. Therefore, it is of less height than that. Its continuity is almost over because of river-erosion. The rivers like the Godavari and the Krishna have developed very wide valleys by cutting it. The highest peak of this range is ‘Vishakhapatnam peak’ (1680 m). Its second highest peak is ‘Mahendragiri’ (1501 m).
The Inner Hills of the Peninsular Plateau
The Satpura Range
The Satpura range is famous among the inner hills. It is a group of the Satpura, the Mahadev and the Maikal hills. The Satpura range is a block mountain which has the valley of the Narmada river on its northern side and that of the Tapi on the western side. The highest peak of the Mahadev hills is ‘Dhoopgarh’ (1350 m) which is also the highest peak of the Satpura range. The highest peak of the Maikal hills is ‘Amarkantak’ from where two prominent rivers, the Narmada and the Son originate. The famous hills station ‘Pachmarhi’ in Madhya Pradesh is near Dhoopgarh.
The Vindhyachal Mountain Range
The second prominent mountain range among inner hills is the Vindhyachal mountain range. This range is a group of the Vindhyachal, the Bhander, the Kaimur and Parasnath hills.
According to geologists the Vindhyachal mountain range is only the escarpment of the rift valley of the Narmada in the same way as the Kaimur hill is of the Son river. The slope of the peninsular India is towards the east or little south-east. That is why rivers like the Godavari and the Krishna originating from the Western Ghats, instead of flowing into the nearby the Arabian Sea, cover a long distance in the eastern direction and flow into the Bay of Bengal. However, the Narmada and the Tapi are exceptions. They do not flow in the direction of the east but the west and drain into the Arabian Sea. It happens because they flow in rift valleys.
The peninsular India is divided into several small plateaus.
(i) The Malwa Plateau
(ii) The Bundelkhand Plateau
(iii) The Baghelkhand Plateau
(iv) The Chotanagpur Plateau
(v) The Deccan Plateau—lt is divided into three parts:
(a) The Deccan lava plateau
(b) The Telangana plateau
(c) The Karnataka (Mysore) plateau
(vi) The Dandakaranya plateau
(vii) The Meghalaya plateau — It is originally the eastern extension of the Deccan plateau. The Garo, the Khasi and the Jaintia hills are located in this plateau from the west to the east respectively. ‘Cherrapunji’ and ‘Mawsynram’ are situated to the south of the Khasi hills. It is also known as the Shillong plateau.