The Western Ghats and Eastern Ghats – UPSC

• The Deccan Plateau, one of the main landmasses of India and a part of its Peninsular Plateau, has the Western Ghats on its west and the Eastern Ghats on its east.
• The Western Ghats, or Sahyadri, form a nearly continuous mountain wall. The Eastern Ghats are broken and discontinuous.

Western Ghats (or The Sahyadris)

Origin and Form

• Older view: the range formed through subduction of the Arabian basin and tilting of the Peninsula to the east and north-east during Himalayan uplift.
• Current view: there is no subduction along this coast, which is a passive continental margin. The Ghats are a great escarpment on the flank of a rift.
  • India separated from Madagascar about 88 million years ago and from the Seychelles about 65 million years ago, the second parting coinciding with the Deccan eruptions.
  • The flank was then raised by rift-related uplift, with erosion on land and sediment loading offshore bending the margin further. The relative share of each mechanism is still debated.
  • The scarp has been worn back inland from the coast since the rifting.
• The result looks like block mountains on the west. The western slope is an escarpment with a stairway form, known as treppen.
  • In the lava country, horizontal flows weather into terraces, giving a “landing stair” look.
• The eastern side is a rolling plateau with an extremely low slope, merging gradually with the Deccan Plateau. From the Deccan the Ghats hardly look like mountains.

• The red arrow and dashed line on this map show the older subduction idea, and the black arrows show the eastward tilt. The slope it marks is the general fall of the plateau to the east and south-east.

• The scarped, block-like western face.

• A flat-topped, stepped summit, the treppen form.

Extent and Status

• It runs from the Tapi valley to Kanyakumari, about 1,600 km long, 30–50 km inland from the coast, and covers about 1,40,000 sq km.
• Sahyadri: the name is used down to about 11°N, the latitude of the Palghat Gap. The range itself continues to about 8°N near Kanyakumari.
• It spreads across six States: Gujarat, Maharashtra, Goa, Karnataka, Tamil Nadu and Keralam (Kerala).
• UNESCO World Heritage Site since 2012, a serial property of 39 components grouped into 7 sub-clusters.
  • It is recognised as one of the world’s eight “hottest hotspots” of biological diversity, a status shared with Sri Lanka, with at least 325 globally threatened species.
  • Older than the Himalaya, as a landmass and in much of its rock.
  • It shapes Indian monsoon weather by intercepting the rain-bearing south-west winds of late summer.
• It is divided into three sections:
  • Northern Western Ghats
  • Middle Sahyadri (Central Western Ghats)
  • Southern Western Ghats

Northern Western Ghats

• Between the Tapi valley and 16°N, a little north of Goa, under a basaltic lava cover. It is highly rugged and dissected by rivers.
• It is built of horizontal sheets of Deccan lava (Deccan Traps), forming a wall over the coastal plain.
• The average height is 1,200 m, and some summits rise higher.
• Important peaks:
  • Kalsubai (1,646 m), the highest point of this section, near Igatpuri.
  • Salher (1,567 m), 90 km or so north of Nashik.
  • Mahabaleshwar (1,438 m).
  • Harishchandragarh (1,424 m).
• Passes: Thal Ghat and Bhor Ghat join the Konkan Plains to the Deccan Plateau by road and rail.
• Satellite imagery reveals many faults running with the range.

The Middle Sahyadri

• It runs from 16°N up to the Nilgiri hills, and is also called the Central Western Ghats (16°–11°N).
• Granites and gneisses form this part, and its relief is rougher than the lava country.
• Dense forest covers it.
• Headward erosion by west-flowing streams has cut deep into the western scarp.
• Average height is 1,200 m, with many summits above 1,500 m.
• Important peaks: Vavul Mala (2,339 m), Kudremukh (1,892 m) and Pushpagiri (1,714 m).
• In Karnataka, the highest point is Mullayanagiri (1,930 m; Mulangiri in older accounts) in the Baba Budan Hills.
• The section has nick points and waterfalls, such as Gersoppa or Jog Falls on the Sharavathi, which drop about 253 m.
• Malnad and Maidan: its two distinctive surfaces in Karnataka, Malnad the forested highlands and Maidan the plateau surface.
• Kaveri: rises in the Brahmagiri Hills at Talakaveri, where the source is a small tank, known as Talkaveri Lake.
• Nilgiri Hills: they join the Sahyadri near the trijunction of Karnataka, Keralam and Tamil Nadu, close to Gudalur, and rise abruptly above 2,000 m.
  • They mark the junction of the Western and Eastern Ghats.
  • Its chief peaks are Doda Betta (2,637 m) and Makurti (2,554 m). Doda Betta is the highest in the Nilgiris.

The Southern Section

• The Palghat Gap (Palakkad Gap) separates the southern part, also called the southern mountain complex, from the main Sahyadri. High ranges end abruptly on either side.
• Palghat Gap:
  • It is about 24–30 km wide and only 75–300 m above sea level, between hills of 1,500–2,000 m.
  • Older accounts call it a rift valley formed between parallel faults.
  • Current work finds no such rift. The gap follows the weak rocks of the ancient Palghat-Cauvery shear zone, and erosion deepened it greatly in the last 40 million years or so, possibly as the monsoon strengthened.
  • Roads and railways use it to cross from the Tamil Nadu plains to the Keralam coast.
  • Moisture-bearing south-west monsoon clouds pass through, carrying some rain inland towards the Mysore region.
• South of the gap lies a tangle of steep, rugged slopes facing both east and west.
• Anai Mudi (2,695 m) tops all of southern India, and three ranges radiate from it:
  • Anaimalai (1,800–2,000 m) to the north.
  • Palani to the north-east. It is often listed at 900–1,200 m, but its plateau stands far higher, reaching 2,533 m at Vandaravu and 2,505 m at Vembadi Shola, with Kodaikanal at about 2,150 m.
  • Cardamom Hills or Elamalai (Ealaimalai) to the south, reaching about 1,922 m at Devar Malai.
• Coast-parallel ranges are usually listed as the Nilgiris, Annamalai and Cardamom, with the Palani as the transverse range.
  • The Nilgiris stand north of the Palghat Gap, so they belong to the Middle section by position.
• These mountains have an average elevation of 1,600–2,500 m.
  • Doda Betta is the highest peak of the Nilgiris.
  • Anamudi is the highest of the Annamalai and of South India.
  • Agasthya Malai (1,868 m) is often given as the highest of the Cardamom Hills. It is in fact a separate range south of the Shencottah Gap, the last block of the Ghats.

Conservation of the Western Ghats

• The Western Ghats Ecology Expert Panel under Madhav Gadgil (2011) recommended treating the whole 1,29,000 sq km chain as ecologically sensitive, in graded zones.
• After objections from the States, a High Level Working Group under K. Kasturirangan proposed about 37%, or 59,940 sq km, as an Ecologically Sensitive Area.
• The draft notification has been reissued several times. The July 2026 draft keeps 56,825.7 sq km across six States, with a ban on mining, quarrying, new thermal plants and new “Red” category industries inside it. It remains a draft while the deadlock with the States continues.
• Heavy rain and landslides are the recurring hazard: 4,728 landslides were recorded in 2018 alone.

Eastern Ghats

Character

• They keep roughly parallel to the east coast, and wide plains separate them from the sea.
• They are a chain of highly broken, detached hills, reaching from the Mahanadi (Odisha) to the Vaigai (Tamil Nadu), and they almost vanish between the Godavari and the Krishna.
• With no unity of structure and no continuity of relief, each hill group is usually studied on its own.
  • Oskar Spate split them into three: Eastern Hills (north), Cuddapah Ranges (centre) and Tamilnad Hills (south).
• Geology: old accounts call them Precambrian fold mountains, younger contemporaries of the Aravalli.
  • Current work reads them as a Proterozoic mobile belt. Metamorphism at about 1,100–900 million years ago ties its main part to the Rayner Complex of East Antarctica, and India and Antarctica were joined at that time. Older events go back to 1,800–1,600 million years.
• Today they are highly dissected and fragmented, standing as hills of denudation roughly along the coast.
• Average elevation: older accounts give 150–300 m (very low). That suits the southern fragments, while the belt as a whole averages about 600 m and the north reaches 900–1,400 m.
• Rocks: several rock systems occur.
  • The Khondalite series is the major one, in the central part of Andhra Pradesh and in Odisha. The name comes from the Kondh hills of Odisha.
  • Charnockites form many bold hills, such as the Biligiri Rangan.
  • Granitic gneiss occurs in the southern part, in Tamil Nadu.
• Rivers have cut broad, wide valleys through them, which is why these mountains are scattered. Older accounts call the valleys U-shaped, a form rivers do not normally carve.

Northern Part: Mahanadi to Godavari

• This is the only stretch with true mountain character, narrowing southward from about 200 km to 100 km. It consists of the Maliya and Madugula Konda ranges.
• Maliya range: generally 900–1,200 m, with Mahendra Giri (1,501 m) as its tallest peak.
  • Older accounts place it in Ganjam, and it stands on the Ganjam and Gajapati border, in Gajapati district. In Odisha it is often quoted as the highest point, though Deomali in Koraput is higher.
• Madugula Konda range: higher, at 1,100–1,400 m, with several summits above 1,600 m.
  • Jindhagada Peak (1,690 m) in the Araku Valley is the highest peak of the Eastern Ghats. Arma Konda stands at 1,680 m, Gali Konda at 1,643 m and Sinkram Gutta at 1,620 m.
• This tract is called the Northern Circars in older accounts, as the highest part of the Eastern Ghats. Strictly, the Northern Circars are the historic coastal territory between the Mahanadi and the Krishna, and the hills rise behind it.

Godavari to Krishna

• Here the Ghats lose their hilly character. Gondwana formations occupy the saddle, the area of the Krishna-Godavari (KG) Basin.

Southern Part

• They reappear as a fairly continuous range in the Cuddapah and Kurnool country of Andhra Pradesh as the arcuate Nallamalai Range, of quartz and slate, at 600–850 m.
  • It was long a Naxalite hideout in Andhra Pradesh. The Union Home Ministry’s 2026 review places no district in the affected category.
• Its southern stretch is the Palkonda range.
• By State:
  • Tamil Nadu: Shevaroy Hills, Javadi Hills.
  • Andhra Pradesh: Palkonda range, Velikonda range, Nallamalai hills.
• Further south the land is very low. Only the Javadi Hills and the Shevaroy-Kalrayan Hills stand out, at about 1,000 m.
• The Biligiri Rangan Hills, in Karnataka at the Tamil Nadu border, reach 1,279 m.
• At the Nilgiris the two Ghats finally meet.

Drainage

• They are hardly a watershed. The great Peninsular rivers cross them.
• Older accounts say no rivers except the Indravati rise here. A few do, though none is large: the Vamsadhara, Nagavali and Rushikulya also begin in these hills.

• On this map “Northern Circars” is the coastal tract, not a hill range, “Venukonda” is Velikonda and “Sechachalam” is Seshachalam.

Ecology and Land Use of the Eastern Ghats

• Biodiversity: more than 3,200 flowering plant species, with forests from moist and dry deciduous to scrub, savanna and pockets of evergreen.
• Tribal land use: podu, or shifting cultivation, on the hill slopes.
  • Some 27 tribal communities live in the Andhra Pradesh section alone.
  • As population has grown, the fallow has shortened, and repeated clearing has left scrub or grass, or bare rock in extreme cases.
• Mining: bauxite in the north, limestone in the Erramala, coal in Khammam, and phosphate and granite elsewhere, all with forest loss.
• Other pressures: overexploitation, habitat destruction and heavy grazing have lowered plant diversity and forest cover.

Difference between Western Ghats and Eastern Ghats

• Rainfall refinement: older accounts place the 100 cm isohyet at the crest of the Western Ghats and give 150 cm or more along the west coast.
  • Those figures are low. Coastal rain exceeds 200 cm and the crest commonly exceeds 500 cm, with Agumbe above 800 cm.
  • Rain then falls sharply to about 90 cm within 10–50 km on the lee side, which is where the 100 cm line really runs.

Significance of the Peninsular Plateau

• Minerals: metals such as iron, manganese, copper, bauxite, chromium and gold, plus mica, and reserves of slate, shale, sandstone and marble.
• Coal: the Gondwana basins hold most of India’s coal. Older counts give 98%, and the current inventory gives over 99%.
• Black soil: a fertile black lava soil over much of the north-western plateau, very useful for cotton.
• Plantations: hilly parts of south India suit tea, coffee and rubber.
• Rice: low-lying parts of the plateau suit it.
• Forests: the highlands bear varied forests and forest products.
• Water: rivers from the Western Ghats offer hydroelectric power and irrigation.
• Hill resorts: Udagamandalam (Ooty), Pachmarhi, Kodaikanal, Mahabaleshwar, Khandala, Matheran and Mount Abu.