Peninsular Plateau

Overview

The Peninsular Plateau is the oldest, most stable, and geologically distinct landmass of India.

Outer Extent (Boundaries of the Plateau)

Extensions Beyond the Main Plateau

• Meghalaya (Shillong) Plateau and Karbi Anglong — eastward extensions beyond the Rajmahal Hills.
• Kutch–Kathiawar (Gujarat) — western extension.
• Rajasthan (partially) — the Aravallis and their eastern flank.

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Key Structural Features

River Flow Direction — General Slope Westward? No.

• Most Peninsular rivers flow from west to east → indicates a general eastward slope (toward the Bay of Bengal).
• Major east-flowing rivers: Mahanadi, Godavari, Krishna, Cauvery — all drain into the Bay of Bengal.
• Exception: Narmada and Tapti flow west to east in normal geography but actually flow EAST to WEST (from Central India toward the Arabian Sea) — through rift valleys (grabens) created by the Narmada-Son fault system.

Horst and Graben Structure

• The Peninsular Plateau has undergone multiple phases of upliftment and submergence with crustal faulting.
• Horst = uplifted fault block (e.g., Vindhya and Satpura ranges)
• Graben = subsided fault block (e.g., Narmada–Son trough — Narmada valley is a graben; Satpura range on its south is a horst)
• Bhima Fault (in Maharashtra/Karnataka) — experiences recurrent seismic activity along the plateau.
• Damodar graben in Chotanagpur — Damodar River flows through a downfaulted trough.

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Divisions of the Peninsular Plateau

I. Northern / Central Peninsular Highlands

1. Marwar Plateau (Mewar Plateau)

• Located in eastern Rajasthan, east of the Aravallis.
• Comprises Vindhyan-age rocks — sandstone, shales, limestone.
• Average elevation: 250–500 m.
• Banas River (with tributaries Berach and Khari) originates in the Aravallis → flows into the Chambal.
• Rolling plain created by river erosion; east of the Aravallis (Marwar Plain is west of Aravallis).

2. Central Highlands (Madhya Bharat Pathar)

• Also called the Madhya Bharat Plateau — forms the northernmost boundary of the Deccan plateau.
• Located east of the Marwar Upland.
• Classic example of relict mountains — highly denuded; disjointed ranges.
• Wider in the west, narrower in the east.
• Average elevation: 700–1,000 m.
• Rolling landscape of rounded sandstone hills.
• Most of the plateau = basin of the Chambal River (flows through a rift valley); main tributaries: Kali Sindh, Banas, Parbati.
• Chambal Ravines to the north — notorious for gully erosion and dacoits historically.

3. Bundelkhand Upland

• Covers parts of UP and MP; composed of old, dissected granite and gneiss.
• Average elevation: 300–600 m; senile topography (old age, heavily eroded, uneven).
• Boundaries: Yamuna (north), Central Highlands (west), Vindhyan Scarplands (east/SE), Malwa Plateau (south).
• Rivers: Betwa and Ken — both flow NE toward Yamuna.
• Not suitable for cultivation due to uneven, heavily eroded surface.

4. Malwa Plateau

• Roughly triangular, based on the Vindhyan Hills.
• Boundaries: Aravallis (west), Madhya Bharat Pathar (north), Bundelkhand (east).
• Composed of extensive lava flow → covered with black cotton soil (regur).
• Dissected by rivers; Chambal ravines mark the northern part.
• Two drainage systems:
  • Arabian Sea side: Narmada, Tapti, Mahi
  • Bay of Bengal side: Chambal, Betwa (join Yamuna → Ganga)

5. Baghelkhand

• Located north of the Maikal Range, bounded by Son River (north).
• Western part: limestone and sandstone; eastern part: granite.
• Uneven topography; elevation varies from 150–1,200 m.
• Water divide: separates Son River system (north) from Mahanadi system (south).

6. Chotanagpur Plateau

• Represents the northeastern projection of the Peninsular Plateau.
• Covers: Jharkhand, Chhattisgarh, Purulia district (West Bengal).
• Series of plateaus at different elevations; average elevation: 700 m.
• Primarily composed of Gondwana rocks — rich in Gondwana coal (Damodar Valley coal fields).
• Drainage: radial pattern; rivers: Damodar, Subarnarekha, North Koel, South Koel, Barkar.
• Hazaribagh Plateau (north of Damodar): average 600 m; appears as a peneplain (nearly flat from extensive erosion); isolated hills; monadnocks.
• Ranchi Plateau (south of Damodar Valley): ~600 m; rolling surface with monadnocks and conical hills.

7. Rajmahal Hills

• Forms the northeastern edge of the Chotanagpur Plateau.
• Dissected into separate plateaus by erosion.
• Predominantly basalt; covered by lava flows.
• Average elevation: 400 m; highest peak: 567 m.

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II. Deccan Plateau

The largest unit of the Peninsular Plateau — triangular in shape; bounded by:

• NW: Satpura and Vindhya Ranges
• North: Mahadev and Maikal Ranges
• West: Western Ghats
• East: Eastern Ghats
• Average elevation: ~600 m; general slope from west to east → rivers flow east (Mahanadi, Godavari, Krishna, Cauvery).

8. Maharashtra Plateau

• Northern Deccan Plateau — primarily underlain by Deccan Trap basaltic rocks.
• Horizontal lava sheets → stepped (trap) topography (flat-topped, steep-sided hills = mesas/buttes).
• Landscape: rolling plain due to long-term weathering of basalt.
• Broad, shallow valleys of Godavari, Bhima, Krishna bordered by flat-topped ridges.
• Entire area covered by black cotton soil (regur).

9. Karnataka Plateau (Mysore Plateau)

• South of the Maharashtra Plateau; average elevation: 600–900 m.
• Extensively dissected by rivers originating from the Western Ghats.
• Divided into two regions:
  • Malnad (= "hill country" in Kannada): deep valleys, dense forests; western Karnataka.
  • Maidan (= "plain" in Kannada): rolling plains with low granite hills; eastern Karnataka.
• Hills generally parallel or perpendicular to the Western Ghats.
• Baba Budan Hills (Chikmagalur): Contains Mullayanagiri (1,930 m) — highest peak in Karnataka and in the Western Ghats of Karnataka.

  Note: Mullayanagiri is sometimes written as Mulangiri or Mullayangiri; 1,930 m is the correct height per Survey of India.

• Plateau narrows southward between W and E Ghats → merges with the Nilgiri Hills.

10. Telangana Plateau

• Average elevation: 500–600 m; southern part is higher than the northern part.
• Features: ghats (hill ranges), hillocks, and peneplains.
• Drained by three systems: Godavari, Krishna, Penneru rivers.

11. Chhattisgarh Plain

• Only true plain in the Peninsular Plateau — a saucer-shaped depression.
• Drained by the upper Mahanadi River.
• Located between Maikal Range (west) and Odisha Hills (east).
• General elevation: 250–330 m.
• Name derived from "thirty-six forts" (Chhattis = 36; Garh = fort) — historically ruled by Haihaivanshi Rajputs.
• Rich in minerals: coal, iron ore, bauxite, manganese, commercial clays.

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III. Extension: Meghalaya (Shillong) Plateau

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Hill Ranges of the Peninsular Plateau

Aravalli Range

MCQ Note: Aravallis are the world's oldest fold mountains (not just India's oldest). The Himalayas are the world's youngest fold mountains.

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Vindhyan Range

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Satpura Range

[UPSC Prelims 2023] Statement 1: "Amarkantak Hills are at the confluence of Vindhya and the Sahyadri Ranges" → WRONG — Amarkantak is at the junction of Vindhya and Satpura ranges (not Sahyadri). Answer: d) None of the three statements are correct.

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Western Ghats (Sahyadris)

Key Peaks — Western Ghats

Key Passes — Western Ghats

Sub-sections of the Western Ghats

Northern Section (Tapti Valley to north of Goa):

• Composed of Deccan Traps lava — highest basalt content.
• Average height: ~1,200 m.
• Notable peaks: Kalsubai, Salher, Mahabaleshwar, Harishchandragarh.
• Key passes: Thal Ghat, Bhor Ghat.

Middle Sahyadri (Goa to ~16°N → Nilgiri junction):

• Dense forests; heavily dissected western scarp (headward erosion of streams).
• Average height: ~1,200 m; many peaks >1,500 m.
• Notable peaks: Vavul Mala, Kudremukh (1,892 m), Pushpagiri.
• Nilgiri Hills abruptly rise to >2,000 m near the Karnataka–Kerala–TN tri-junction — where Western and Eastern Ghats converge.

Southern Section (south of Palghat Gap):

• Separated from main Sahyadri by Palghat (Palakkad) Gap — a rift valley connecting TN plains to Kerala coast.
• Anai Mudi (2,695 m) — highest peak in South India.
• Three ranges radiate from Anai Mudi:
  1. Anaimalai Hills (1,800–2,000 m) — north
  2. Palani Hills (900–1,200 m) — NE; Kodaikanal hill station
  3. Cardamom Hills (Ealaimalai / Yela Mala) — south; Periyar Tiger Reserve; Silent Valley NP

Rain Shadow Effect of Western Ghats

• Western (windward) slopes: heavy SW monsoon rainfall (3,000–4,000 mm).
• Eastern (leeward) slopes: rain shadow zone — much drier (600–700 mm).
• This explains why northern Karnataka (Hyderabad-Karnataka), Marathwada (Maharashtra), Vidarbha, and parts of Andhra Pradesh are semi-arid despite being geographically "close" to the sea.

Why Western Ghats Rivers Don't Form Deltas

Western Ghats rivers (flowing west to the Arabian Sea) do not form deltas because:

1. Short course — source to sea distance too short (<100 km typically)
2. Steep gradient — rapid descent leaves no time/distance for sediment deposition
3. Rocky, well-vegetated terrain — limited sediment availability
4. Strong Arabian Sea wave action (especially during SW monsoon) — erodes any deposited sediment

• Result: Rivers form estuaries (funnel-shaped tidal mouths) instead of deltas.

[UPSC Mains 2013] "There is no formation of deltas by rivers of the Western Ghats. Explain why." — Use the above 4-point framework.

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Eastern Ghats

Key Peaks — Eastern Ghats

Sub-sections of the Eastern Ghats

Northern section (Mahanadi to Godavari — "true mountain character"):

• Maliya Range (900–1,200 m): Mahendra Giri is tallest.
• Madugula Konda Range (1,100–1,400 m): Jindhagada Peak (1,690 m) — highest peak of Eastern Ghats; also known as Arma Konda and Sitamma Konda.

Between Godavari and Krishna: Eastern Ghats lose hilly character → occupied by Gondwana formations.

Cuddapah–Kurnool section (AP): Reappear as the Nallamalai Range (600–850 m) — Nagarjunasagar–Srisailam Tiger Reserve; Amrabad Tiger Reserve in Telangana portion.

Southern section: Javadi Hills and Shevaroy–Kalrayan Hills (~1,000 m, TN). Southern Eastern Ghats merge with Western Ghats at the Nilgiris.

Junction of Eastern and Western Ghats

• The two ranges meet at the Nilgiri Hills (Karnataka–Kerala–TN tri-junction).
• Sathyamangalam Tiger Reserve (Tamil Nadu–Karnataka border): key ecological corridor linking Eastern Ghats with Western Ghats.

[UPSC Prelims 2017] Ecologically important link between Eastern and Western Ghats: a) Sathyamangalam Tiger Reserve ✓ — it connects to Biligiriranganatha Swamy Temple WLS, Sigur Plateau, Mudumalai, and Bandipur NP.

[UPSC Prelims 2008] Hills where Eastern and Western Ghats meet: c) Nilgiri Hills ✓

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Significance of the Peninsular Plateau

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UPSC Corner

Key Peaks — Quick Reference Table

Key One-Liners for Prelims

• Peninsular Plateau = ~16 lakh km²; average elevation 600–900 m; oldest, most stable landmass in India
• Peninsular Plateau = Gondwana fragment; made of ancient Archaean gneisses + schists (~4 billion years)
• Most Peninsular rivers flow west to east (east slope) → exception: Narmada and Tapti flow east to west through rift valleys (grabens)
• Aravallis = world's oldest fold mountains (~3,000 Ma); ~800 km (Delhi to Palanpur, Gujarat); highest = Guru Shikhar (1,722 m) at Mt. Abu
• Western Ghats = UNESCO WHS inscribed 2012; one of 8 global biodiversity hotspots; highest = Anai Mudi (2,695 m)
• Palakkad (Palghat) Gap: lowest point (~140 m) in Western Ghats; allows SW monsoon into TN; road + railway link
• Eastern Ghats highest: Jindhagada / Arma Konda (~1,690 m) in Madugula Konda Range, AP
• Eastern and Western Ghats meet at Nilgiri Hills; Sathyamangalam TR = key ecological corridor between them
• Chhattisgarh Plain = only true plain in the Peninsular Plateau; upper Mahanadi basin; elevation 250–330 m
• Meghalaya Plateau separated from main peninsular block by Garo–Rajmahal Gap (Malda Fault)
• Mawsynram (Meghalaya) = wettest place on Earth
• Satpura = horst between Narmada graben (north) and Tapti (south); highest = Dhupgarh (1,350 m)
• Amarkantak (1,127 m) = source of Narmada, Son, and Johila rivers; at junction of Vindhya and Satpura
• Western Ghats rivers form estuaries, not deltas — short course, steep gradient, strong wave action
• Rain shadow of Western Ghats → semi-arid eastern slopes (northern Karnataka, Marathwada, Vidarbha)

Mains GS1 Questions

1. "Identify and describe the major physiographic divisions of the Peninsular Plateau. How does the plateau influence the drainage pattern of Peninsular India?"
2. "The Western Ghats are considered one of the world's biodiversity hotspots. Discuss the ecological significance of the Western Ghats and the threats they face."
3. "Compare the Eastern and Western Ghats in terms of origin, elevation, continuity, and ecological significance."
4. "Why do rivers of the Western Ghats not form deltas? Discuss the factors responsible."

MCQ Trap Awareness

• Trap: "Aravallis are India's oldest mountains" → Imprecise — Aravallis are also the world's oldest fold mountains (~3,000 Ma pre-Cambrian); say "world's oldest".
• Trap: "Anai Mudi is the highest peak in the Western Ghats only" → Incomplete — it is also the highest peak in South India and in the entire Peninsular Plateau south of the Vindhyas.
• Trap: "Amarkantak is at the junction of Vindhya and Sahyadri" → Wrong — Amarkantak is at the junction of Vindhya and Satpura ranges (UPSC 2023 PYQ trap).
• Trap: "Western Ghats inscribed as UNESCO WHS in 2007" → Wrong — inscribed in 2012.
• Trap: "Jindhagada Peak is in Orissa" → Wrong — it is in Andhra Pradesh (Madugula Konda Range, Visakhapatnam district area).
• Trap: "Eastern Ghats are continuous like Western Ghats" → Wrong — Eastern Ghats are discontinuous and fragmented (no structural unity); Western Ghats are a continuous escarpment.
• Trap: "Narmada flows east to west due to high elevation of Western Ghats" → Incomplete/wrong framing — Narmada flows west through a rift valley (graben) between the Vindhyan horst (north) and Satpura horst (south).
• Trap: "Chhattisgarh Plain is in the Northern Plains" → Wrong — it is the only true plain within the Peninsular Plateau (saucer-shaped basin of upper Mahanadi).
• Trap: "Malnad and Maidan are divisions of Maharashtra Plateau" → Wrong — Malnad (hill country) and Maidan (plains) are divisions of the Karnataka/Mysore Plateau.
• Trap: "Dhupgarh is the highest point of MP and India's highest plateau peak" → Only partly right — Dhupgarh (1,350 m) is the highest point in Satpura range and Madhya Pradesh; Anai Mudi (2,695 m) is higher but in Kerala.
• Trap: "Sathyamangalam is in Karnataka" → Wrong — Sathyamangalam Tiger Reserve is in Tamil Nadu (Erode district), at the border with Karnataka.