Physiography of Peninsular India - Peninsular Hills

Indian Peninsula is one of the world’s oldest geological structures. It is also a tectonically stable region and therefore have lower possibilities of earthquakes. This region has gone through several erosional cycles and hence present a complex physiography too. The general elevation of the plateau is from the west to the east.

• Geologically it is a complex geological mix of Archean, Gondwana, Cuddappah and Dharwar rock formations. 
• Delhi ridge in the northwest, (extension of Aravallis), the Rajmahal hills in the east, Gir range in the west and the Cardamom hills in the south constitute the outer extent of the Peninsular plateau. 
• However, an extension of this is also seen in northeast, in the form of Shillong and Karbi-Anglong plateau.
• Peninsular India is made up of a series of patland plateaus such as the Hazaribagh plateau, the Palamu plateau, the Ranchi plateau, the Malwa plateau, the Coimbatore plateau and the Karnataka plateau, etc. 
• Northwestern part of the plateau has a complex relief of ravines and gorges. Ex. ravines of Chambal, Bhind and Morena.

HILLS OF PENINSULA

Aravalli Mountain Range:

• One of the oldest fold mountains of the world.
• Extends from Delhi ridge up to Palanpur (Gujarat).
• Covers Delhi, Haryana, Rajasthan & Gujarat. 
• Its highest peak is Guru Shikhar (on Abu Hills) in Rajasthan. Mt. Abu is also located nearby.

Vindhyachal Mountain Range:

• It is a group of hills of Vindhyan, Bharner and Kaimur.
• It is the northern escarpment of the Narmada valley and act as a major watershed between North and South India. 
• Bhander plateau lies on the Eastern sides of Bharner hills.
• Malwa plateau lies in the Northwestern part and Baghelkhand plateau lies in the Eastern part.

Western Ghats:

During the split of Gondwana, a fault valley was formed which was filled with water to form Arabian sea. Western ghats were left as the escarpments of this fault valley. The steep slopes of the Western ghats of the Peninsular India shows that fault. 

Major geological transformations took place as the peninsula moved northwards and drifted over the present-day Reunion islands – localised volcanic centre in the earth’s lithosphere 200-300 km across, which has remained active for several million years.

It moved up in this drift and the heat beneath generated basaltic magma which rose into lithosphere causing an uplift by crustal arching. It was this event which happened some 120-130 m.y.a. that resulted in the uplift of the Western Ghats and tilted the Indian Plate in easterly direction.

• They are also known as ‘Sahyadris’.
• Their steep seaward slopes are deeply dissected by streams and canyonlike valleys, but on the landward side their slopes are gentle and give way to wide, mature valleys.
• These are older than the Himalaya mountains. 
• It influences the Indian monsoon weather pattern.
• It also has an exceptionally high level of biological diversity and endemism and is recognized as one of the world’s eight ‘hottest hotspots’ of biological diversity. 
• The forests of the site include some of the best representatives of non-equatorial tropical evergreen forests anywhere and are home to at least 325 globally threatened flora, fauna, bird, amphibian, reptile and fish species.
• Since the Western Ghats are a result of a domal uplift, the underlying rocks are ancient – around 2000-million-year-old. The oldest of these rocks are found in the Nilgiris and the High Ranges of the southern Western Ghats. 
  
  Northern Sahyadri:

• Extends from Tapi River to the origin of Malprabha River (16-degree North).
• Important peaks: Kalsubai (highest), Mahabaleshwar, Harishchandragad.
  
  

Middle Sahyadari:

• Extends from 16-degree N to Nilgiris hills.
• Southern demarcation is ‘Palghat gap’ which separates Nilgiris and Annamalai.
• Important peaks: Kudremukh (highest), pushpagiri (Kaveri originates near Pushpagiri) etc. 
• At Nilgiris, Eastern and Western ghats merge. 
• Highest peak of Nilgiris- Dodabetta (2^nd highest of South India)
• Silent valley national park is in Nilgiris having River ‘Kunthi’ passing through it.
  
  

Southern Sahyadari:

• Extends from south of Palghat, from the Annamalai mountains to the Nagercoil hills (South of Cardamom)
• Highest peak of Annamalai- Anaimudi (Also the highest peak of Western ghats as well as South India)
• Palni hills (northeast direction) emerge south of Annamalai hills

Eastern Ghats:

• It extends from Mahanadi to Nilgiris.
• Its height is lesser than western ghats. 
• Important peaks – Jindhagada peak (highest), Mahendragiri, Niyamgiri.
• Important ranges – Nallamala, Erramala, Velikonda, Palkonda, Nagari, Seshachalam etc.
• Venkateshwara Tirupati temple is located in Tirumala hills which are located in the Southeastern part of Palkonda range. 

Satpura Range:

• It is a group of Satpura, Mahadev and Maikala hills.
• Hills of Satpura and Mahadev are situated on the border of Madhya Pradesh and Maharashtra. Satpura are block mountains having Narmada valley towards its North and Tapi valley towards its South. Highest peak of Satpura is ‘Dhoopgarh’ which lies in Mahadev hills. Panchmarhi is located near Dhoopgarh. 
• Hills of Maikal are situated on the borders of Madhya Pradesh and Chhattisgarh. Highest peak is Amarkantak.
• Asirgarh pass is situated in Satpura range. (Asirgarh fort was described as the ‘key to the South’/ ‘gateway of South India’).

Gawilgarh hills:

• Situated in South of Tapi and is mainly spread in Amravati, Maharashtra.

Ajanta hills:

• It is the northeast extension of Satmala hills. It is spread in Aurangabad, (Maharashtra). Purna River (tributary of Godavari) originates from these hills (Gautala wildlife sanctuary).

Garhjat Hills:

• Present in Odisha and known as ‘Odisha highland’.
• Vaitarni and Brahmani flow through these.

Balaghat range:

Mainly spread in Maharashtra and is a Southward extension of Harishchandra range in Western ghats.