They originate in Gujarat (at Kalyanpur) and extend till Haryana. They terminate in the Delhi ridge.
They have a maximum extent of 800 km
They are old fold mountain ranges, one of the oldest tectonic mountains in the world.
Rocks that make up the Aravallis are more than 2 billion years old.
Unlike other fold mountains, Aravallis have an average elevation in the range of 400-600m only. This is because throughout their geological history they were subjected to the processes of weathering and erosion.
Only a few peaks reach an elevation of above 1000m. These include – Mt. Gurushikhar (1722m, the highest point of Aravallis), Mt.Abu (1158m, it’s part of a plateau).
Geologically, they are mainly made up of Dharwad igneous and metamorphic rocks.
They contain the largest marble deposits in India.
Rivers Banas, Luni, Sabarmati are born in Aravallis. Banas is a tributary of Chambal. Luni is an ephemeral river which terminates in the Rann of Kutchch.
They contain several passes that cut through them, especially between Udaipur and Ajmer like Palghat, Dewar, Desuri etc.
They also contain several lakes such as Lake Sambhar (largest inland saline water body in India), Lake Dhebar (south of Aravallis), Lake Jaisamand (in the Jaisamand wildlife sanctuary) etc.
These are non-tectonic mountains; they were formed not because of plate collision but because of the downward faulting of the Narmada Rift Valley (NRV) to their south.
They extend for 1200km from Bharuch in Gujarat to Sasaram in Bihar.
Geologically, they are younger than Aravallis and Satpura hills.
Their average height is in the range of 300-650m.
They are made up of older Proterozoic rocks. They are cut across by Kimberlitic piles (diamond deposits)
They are known by local names such as Panna, Kaimur, and Rewa etc.
They rise from the NRV in the form of steep, sharp slopes called the escarpments. These escarpments are well developed in Kaimur and Panna regions.
Satpura range is a combination of Satpura, Mahadeo, and Maikala hills.
Satpura hills are tectonic mountains, formed about 1.6 billion years ago, as a result of folding and structural uplift. They are a Horst landform.
They run for a distance of about 900km.
Mahadeo hills lie to the east of Satpura hills. Pachmarhi is the highest point of the Satpura range. Dhupgarh (1350m) is the highest peak of Pachmarhi.
Maikala hills lie to the east of Mahadeo hills. Amarkantak plateau is a part of the Maikala hills. It is about 1127m.
The plateau has the drainage systems of Narmada and Son; hence it has drainage into the Bay of Bengal as well as Arabian sea.
These are mostly situated in the States of Madhya Pradesh and Chhattisgarh.
These hills are rich in bauxite, due to the presence of Gondwana rocks.
Dhuandhar waterfalls over the Narmada is situated MP.
They extend between Diu island near Gujarat to Kanyakumari in the south.
They form the western edge of the Deccan plateau.
They appear to be rising abruptly from the west coast plains to an altitude of 1km from the mean sea level.
They have a gentle slope towards their eastern edge, from the Deccan plateau, and don’t appear to be a tall range of hills.
They were formed due to faulting along the western edge of the Deccan plateau, during the collision of the Indian plate with the Eurasian plate. This led to the submergence of the western coast, as well as an abrupt escarpment of the Western Ghats along the plateau’s western edge.
They are divided into three sections – northern section, middle section, and southern section.
The Western Ghats of this section is also known as the Sahyadris. They are located in Maharashtra.
The average elevation of Sahyadris is 1200m above the mean sea level.
Sahyadris are made of volcanic igneous rocks (basalt). Hence they are geologically younger than the rocks in the other sections of the Western Ghats.
Mahabaleshwar plateau is the highest region of the Sahyadris. River Krishna has its origin from this plateau.
Important peaks of the Sahyadris include – Kalasubai peak (1.64km, the tallest peak of the Sahyadris), Salher peak (1.56km), Harischandragarh peak (1.4km) etc.
Sahyadris give rise to more number of large rivers, relatively than any other section of the Ghats. Hence they form the most important watershed of south India.
Some of the important passes of this section include the Thalghat gap (the route between Mumbai and Nashik passes through this) and Bhorghta gap (the route between Mumbai and Pune passes through this)
This section runs through the States of Karnataka and Goa. It terminates in the Nilgiri, where it joins the Eastern Ghats.
Bababudan hills of Karnataka are a part of this section. They are famous for their coffee plantations. River Tungabhadra has one of its originating streams (Bhadra) coming from these hills.
They are made of igneous and metamorphic rocks like the granite and gneiss.
They have dense forests and a number of short streams originate from them. This resulted in a headward erosion of these hills, leaving many gaps in the ranges.
Their average elevation is around 1200m. They include prominent peaks such as the Vavulmala (2339m), Kudremukh (1892m), Pushpagiri (1714m) etc.
Nilgiri are the prominent hills of this section. They rise abruptly at the trijunction of Karnataka, Tamil Nadu, and Kerala to a height of up to 2000m. The highest hills of Nilgiri are the Ootacamund hills. Doda betta (2630m) is the highest peak in the Nilgiri.
Nilgiri are Block Mountains, they rose between two faults and are hence considered to be Horst landforms.
This includes the hill ranges of Annamalai and Cardamom.
Palghat gap (Palakkad gap) is the largest gap in the Western Ghats (about 24km wide). It separates the Nilgiri from the Annamalai hills.
Anaimudi peak (2690m) is the highest point of Annamalai hills, also the highest point of peninsular India. Palani hills are a part of the Annamalai range. They are made of Dharwad igneous rocks. Kodaikanal hill station is a part of the Palani hills.
Cardamom hills are to the south of Annamalai hills and are separated from them by the Shenkottai pass. Also known as Anaimalai, these hills are famous for Cardamom cultivation.
Periyar River originates close to the Annamalai hills and flows into the Arabian Sea.
Varushnad hills are a part of the Cardamom hills. River Vaigai originates here.
Agasthamalai hills are the southernmost section of the Western Ghats. Situated in Kerala and Tamil Nadu. Agasthamalai peak is the southernmost peak of peninsular India.
They extend between the rivers Mahanadi and Vaigai.
They are mainly composed of Dharwad igneous and metamorphic rocks.
Unlike the Western Ghats, these are low lying hills. They are a discontinuous mountain range, unlike the Western Ghats.
They comprise a series of discontinuous hill ranges such as – Odisha hills (Maliya hills), Nallamala hills, Palakonda hills, Velikonda hills, Javadi hills, and Shevaroy hills.
Mahendragiri peak (1501m) is the highest point of Odisha hills.
Between Odisha hills and the Godavari basin, there are some prominent hill ranges such as the Madugula Konda range. It has an average elevation in the range of 900-1100m It has some of the highest peaks of the Eastern Ghats like the Jindhagada peak (1690m), Arma Konda (1680m), Gali Konda (1643m) etc
They almost absent between Madugula Konda range and Nallamala hills. This region is made up of the Godavari-Krishna delta.
Nallamala hills are situated in Andhra Pradesh. They are made up of Proterozoic sedimentary rocks. Their average elevation is in the range of 600-850m.
To their south are the Velikonda hills, Palakonda hills, and the Seshachalam range in Andhra Pradesh.
Javadi hills and Shevaroy hills are situated in Tamil Nadu. To the south, Eastern Ghats merge with the Western Ghats at the Nilgiri.