The Himalayan Ranges — Part I

Overview of the Himalayan Ranges

The Himalayas (Sanskrit: Hima = snow, Alaya = abode → "Abode of Snow") are a young fold mountain system formed by continent-continent convergence between the Indian Plate and the Eurasian Plate.

Extent and coverage:

• Stretch from Nanga Parbat (8,126 m) in the northwest to Namcha Barwa (7,782 m) in the northeast — approximately 2,400 km in length.
• Width varies from ~400 km in Kashmir to ~150 km in Arunachal Pradesh.
• Fall mainly in India, Nepal, and Bhutan; northern slopes extend into Tibet (China); western extremity reaches Pakistan and Afghanistan.

Geological character:

• Young, weak, and geologically unstable landmass — still under tectonic stress.
• Characterised by ongoing faulting, folding, and thrusting.
• Rivers are in their youthful stage — actively downcut, creating deep gorges, V-shaped valleys, rapids, and waterfalls.

UPSC Prelims 2012: Features like deep gorges, U-turn river courses, parallel mountain ranges, and steep gradients causing landslides are all evidence of the Himalayas being young fold mountains. Answer: (d) All four ✓

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Formation of the Himalayas — Tectonic History

Stage 1: Pangea and Tethys Sea (~250 million years ago)

• A supercontinent called Pangea was surrounded by a super-ocean called Panthalassa.
• ~150 million years ago, Pangea split into:
  • Laurasia / Angaraland → present-day North America, Europe, and Asia
  • Gondwanaland → present-day South America, Africa, South India (Peninsular India), Australia, and Antarctica
• A long, narrow sea called the Tethys Sea (Tethys Geosyncline) formed between Laurasia and Gondwanaland.
• Rivers flowing into the Tethys deposited enormous amounts of sediment (future Himalayan rock).

Stage 2: Northward Drift of the Indian Plate (~150 mya to ~50 mya)

• The Indian Plate separated from Gondwanaland and drifted northward at a rate of ~5–10 cm/year.
• It was separated from Gondwanaland by the opening of what is today the Indian Ocean.

Stage 3: Collision and Himalayan Uplift (~50 million years ago to present)

• The Indian Plate collided with the Eurasian Plate approximately 50–55 million years ago (Eocene epoch).
• The sediments of the Tethys Geosyncline were compressed, folded, and uplifted to form the Himalayas.
• The Indian Plate continues to push northward at ~2 cm/year → Himalayas are still rising (~1–5 mm/year).
• The Indus-Tsangpo Suture Zone (ITSZ) marks the exact line of collision between the two plates.
• Associated geological structures: Main Central Thrust (MCT), Main Boundary Thrust (MBT), Himalayan Frontal Thrust (HFT).

Formation of the Indo-Gangetic Plain

• The collision created a depression (foredeep/foreland basin) to the south of the rising Himalayas.
• Himalayan rivers carried alluvium and filled this depression over millions of years.
• The Tethys Sea completely disappeared, leaving behind the Indo-Gangetic-Brahmaputra Plain — the world's largest alluvial plain.
• Three main river systems — Indus, Ganga, Brahmaputra — are primary contributors to this plain.

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Classification of Himalayan Ranges

The Himalayas can be classified into five major divisions (north to south):

Three Parallel Ranges (Main Arc)

Between the Tibetan Plateau and the Ganga Plain, three parallel ranges form a convex arc facing south:

• Greater Himalayas
• Lesser Himalayas (Himachal)
• Shiwaliks

General orientation:

Slope Asymmetry

• Himalayan folds are asymmetrical: valleys = synclines, hills = anticlines.
• Result: Steep south-facing slopes and gentle north-facing slopes (hogback topography).
• Climbing Everest from the north (Tibet) is topographically easier but China restricts access, so most climbers use Nepal's steeper south routes.

Syntaxial Bends

• At both ends, the Himalayan ranges sharply bend southward — called syntaxial bends.
• Western syntaxial bend: near Nanga Parbat (Indus Gorge — world's deepest gorge).
• Eastern syntaxial bend: near Namcha Barwa (Brahmaputra Gorge — also among the world's deepest).

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The Trans-Himalayas (Tibetan Himalayas)

• Located immediately north of the Greater Himalayas, mostly in Tibet.
• Average elevation: ~3,000 m.
• Length: ~1,000 km (east–west), occurring only in the western part (Ladakh, J&K, HP).
• Width: ~40 km at extremities, widening to ~225 km in the centre.

Major Ranges of the Trans-Himalayas

Karakoram Range

• Northernmost Trans-Himalayan range in India; also called Krishnagiri.
• Extends ~800 km eastward from the Pamirs (Pakistan).
• Contains K2 (8,611 m) — also known as Godwin-Austen or Qogir:
  • Second highest peak in the world (after Mt. Everest)
  • Highest peak in the Indian Union
• The Ladakh Plateau lies northeast of the Karakoram: includes Soda Plains, Aksai Chin (under Chinese control), Lingzi Tang, Depsang Plains, Chang Chenmo.
• Has the maximum concentration of glaciers outside the polar regions — includes Siachen, Hispar, Biafo, Baltoro glaciers.

Ladakh Range

• Situated south of Karakoram, north of Zanskar Range, runs parallel to both.
• Very few peaks exceed 6,000 m.

Zanskar Range

• Situated south of Ladakh Range.
• Average height: ~6,000 m.
• Houses Nanga Parbat (8,126 m) — called "Naked Mountain" due to its isolation from similarly tall Karakoram peaks.

Kailas Range (Gangdise)

• Located in western Tibet; an offshoot of the Ladakh Range.
• Mount Kailas (6,714 m) — highest peak.
• The Indus River originates from the southern slopes of the Kailas Range near Lake Manasarovar (also called Mapang Yongcuo).

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The Greater Himalayas (Himadri)

• Extends 2,500 km from Nanga Parbat to Namcha Barwa.
• Width: 160–400 km.
• Average elevation: ~6,000 m — contains all peaks above 8,000 m.
• Composition: Central crystallines (granite, gneiss) overlain by metamorphosed sedimentary rocks (limestone, quartzite).

Major Peaks

Updated 2020: Mt. Everest's official height revised to 8,848.86 m by China-Nepal joint survey (from the previously accepted 8,848 m). Both countries agreed on this new measurement.

Regional names of Mt. Everest:

• Sagarmatha (Nepal) — "Goddess of the Sky"
• Qomolangma (Tibet/China) — "Mother of the World"
• First surveyed by George Everest (Surveyor General of India) in 1841; established as world's highest peak by the Great Trigonometrical Survey of India.

Perpetual Snow and Glaciers

• Most peaks remain under perpetual snow year-round.
• Snowline elevation varies:
  • Eastern Himalayas (Kumaon): ~3,500 m
  • Western (Punjab) Himalayas: ~2,500 m (lower due to less precipitation, not latitude)
  • On south-facing slopes: lower snowline (more precipitation)
  • On north-facing slopes: higher snowline (rain shadow, drier)

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The Lesser Himalayas (Himachal / Middle Himalayas)

• Located between Greater Himalayas (north) and Shiwaliks (south).
• Runs parallel to both ranges.
• Length: ~2,400 km | Width: ~50 km.
• Elevation: 3,500–4,500 m; many peaks exceed 5,050 m; some remain snow-covered year-round.
• South-facing slopes: steep, barren (steep slopes prevent soil formation).
• North-facing slopes: gentler, forest-covered.

Important Ranges in the Lesser Himalayas

Hill Stations in Lesser Himalayas

Shimla, Mussoorie, Nainital, Chakrata, Ranikhet, Almora, Lansdowne, Chail, Dalhousie, Dharamshala, Kasauli, Mussorie, Darjeeling, Mirik.

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The Shiwaliks (Outer Himalayas)

• The youngest, outermost, and lowest Himalayan range.
• Length: ~2,400 km (discontinuous); Width: 10–50 km.
• Elevation: 900–1,200 m (rarely exceeding 1,500 m).
• Composed of soft, unconsolidated rock (sandstone, conglomerate, boulder clay) — highly prone to erosion.
• Also called: Manak Parbat (ancient name), Churia Hills (Nepal), Dundwa Range (UP).

Dun / Doon Valleys

• Longitudinal valleys between the Lesser Himalayas and Shiwaliks are called Duns (in the west) or Duars (in the east).
• Examples: Dehradun (Uttarakhand), Patlidun, Kotlidun, Chandigarh-Kalka area.
• Duns contain coarse alluvial fans (bhabar) and are important agricultural and urban zones.

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Purvanchal (Eastern Hills)

The Purvanchal (meaning "Eastern Range") are the eastern extensions of the Himalayas that run along India's northeastern borders with Myanmar and Bangladesh. Unlike the main Himalayan arc, they run largely north–south.

Key Features

• Elevation: Generally 1,000–3,000 m — significantly lower than the main Himalayan arc.
• Composition: Largely sandstone, limestone, and shale (sedimentary) with some crystalline rocks; covered in dense tropical forests.
• Orientation: North–South (unlike the main E–W Himalayan arc) — a consequence of the curvature of the Indian Plate.
• Part of the Indo-Myanmar Ranges — the tectonic suture between the Indian subcontinent and the Southeast Asian landmass.

Sub-Divisions (North to South)

UPSC Significance

• Saramati (3,826 m) is the highest peak of Purvanchal.
• Loktak Lake (largest freshwater lake in NE India) and Keibul Lamjao National Park (only floating national park in the world) are near Manipur Hills.
• The Purvanchal acts as a climatic barrier — orographic rainfall on the western slopes; rain shadow on the eastern.
• Passes: Diphu/Pangsau Pass, Patkai Pass connect to Myanmar's Sagaing region and the old Stilwell Road (Ledo Road).

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Important Passes of the Himalayas

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Major Infrastructure Projects (Updated to 2026)

Atal Tunnel (Rohtang Tunnel)

• Inaugurated by PM Modi on October 3, 2020.
• Length: 9.02 km — world's longest highway tunnel above 10,000 feet (World Book of Records).
• South portal: 3,060 m | North portal: 3,071 m (Sissu, Lahaul Valley).
• Connects Manali to Keylong / Lahaul-Spiti; bypasses Rohtang Pass.
• Reduces distance by 46 km (116 km → 71 km); saves ~3–4 hours.
• Built by BRO; construction started 2002 (delayed by 18 years).
• Provides all-weather connectivity to Lahaul-Spiti (earlier cut off for ~6 months/year).

Sela Tunnel (Arunachal Pradesh)

• Inaugurated by PM Modi on March 9, 2024.
• Location: NH13 connecting Tezpur (Assam) to Tawang (West Kameng, Arunachal Pradesh).
• Altitude: ~13,000 feet (~3,962 m) — highest bi-lane tunnel in the world.
• Structure: Tunnel 1 = 980 m (single tube); Tunnel 2 = 1,555 m (twin tube: one traffic, one emergency).
• Cost: ₹825 crore | Built by BRO using New Austrian Tunnelling Method.
• Reduces Dirang–Tawang distance by 10 km; provides all-weather access to Tawang.
• Strategic significance: Better movement of troops and equipment toward LAC with China.

Zoji La Tunnel (Under Construction)

• Location: NH1 (Srinagar–Leh highway); under Zoji La Pass (3,528 m) in J&K.
• Objective: Provide all-weather connectivity between Srinagar and Leh (Zoji La currently closed ~6 months/year due to snow).
• Length: ~14.15 km — will be the longest road tunnel in Asia when complete.
• Implementing agency: NHIDCL (National Highways and Industrial Development Corporation).
• Target completion: ~2028.
• Strategic significance: Critical supply line to Ladakh; reduces vulnerability during winter cut-off.

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Current Affairs: Himalayan Hazards (2023–2026)

Joshimath (Jyotirmath) Land Subsidence — January 2023

• Location: Joshimath, Chamoli district, Uttarakhand (altitude ~1,890 m; gateway to Badrinath).
• Event: Rapid land subsidence of 5.4 cm within 12 days (December 27, 2022 – January 8, 2023); over 868 structures cracked.
• Causes (multi-factor):
  1. Town built on ancient landslide debris (identified as far back as the 1976 Mishra Commission Report).
  2. Deforestation: Forest cover decreased ~24% between 2016–2022; loss of root cohesion.
  3. Internal erosion by water seeping underground (rainwater, snowmelt, hotel/house drainage) — IIT-Roorkee finding.
  4. Uncontrolled construction and infrastructure development on unstable terrain.
  5. Vibrations from road/tunnel construction work (NTPC Tapovan Vishnugad HEP tunnel nearby).
• Response: Declared a landslide-subsidence zone; 60+ families evacuated; construction activities halted.
• UPSC Mains Angle: "Discuss the factors responsible for the Joshimath land subsidence crisis and suggest measures to prevent such disasters in Himalayan towns."

Sikkim GLOF — October 3–4, 2023

• Full name: South Lhonak Glacial Lake Outburst Flood (GLOF), Sikkim.
• Trigger: A permafrost landslide (~14.7 million m³ of frozen lateral moraine) collapsed into South Lhonak Lake at 5,200 m elevation at ~22:12 IST on October 3, 2023.
• Wave: Generated a 20-metre-high displacement wave that overtopped and breached the frontal moraine.
• Volume released: ~50 million m³ of water; peak discharge 48,500 m³/s.
• Travel: Flood cascaded 385 km along the Teesta River all the way to Bangladesh.
• Death toll: ~92 confirmed dead; 74+ missing (as of October 18, 2023).
• Infrastructure damage:
  • Teesta III Hydropower Dam completely destroyed.
  • 31 major bridges lost.
  • ~25,900 buildings damaged or destroyed.
  • ~270 km² agricultural land affected.
  • 45 secondary landslides triggered.
  • ~270 million m³ of sediment eroded.
• Confirmed by ICIMOD: Climate change played a key role in accelerating glacier melt and glacial lake expansion.
• UPSC Mains Angle: "What are GLOFs? Examine the causes and consequences of the 2023 Sikkim GLOF and suggest mitigation measures."

Himalayan Glacier Status (Updated 2025)

• Total glaciers in Indian Himalayas (GSI): 9,575 glaciers; 267 exceed 10 km² in area.
• ISRO Study (Indus, Ganga, Brahmaputra basins including Karakoram): 34,919 glaciers covering 75,779 sq km.
• Glacial lake expansion (ISRO 2024): 601 of 676 monitored glacial lakes have expanded more than twice — indicating significant retreat.
• Retreat rate: Average ~0.5 m vertical ice thickness loss per year since 2000.
• Climate projection: Up to 75% glacier volume loss by 2100 under high-emissions scenario (Hindu Kush Himalaya Assessment).
• Karakoram Anomaly: Some Karakoram glaciers are stable or advancing due to unique climate dynamics (known as the "Karakoram Anomaly") — while most Himalayan glaciers retreat.
• "Third Pole" designation: The Hindu Kush–Himalaya–Karakoram region is called the Third Pole — largest concentration of ice outside the Arctic and Antarctic.

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UPSC Corner

Key One-Liners for Prelims

• Himalayas formed by continent-continent convergence (Indian Plate + Eurasian Plate)
• K2 (8,611 m) = second highest globally = highest in the Indian Union
• Kangchenjunga (8,586 m) = third highest globally = highest peak on Indian territory
• Nanda Devi (7,816 m) = highest peak entirely within India (Kangchenjunga is on border)
• Mt. Everest height = 8,848.86 m (revised 2020 by China-Nepal survey)
• Karakoram = maximum glacier development outside polar regions
• Siachen Glacier = largest glacier outside polar and sub-polar regions = 75 km long
• Atal Tunnel = world's longest highway tunnel above 10,000 ft; opened 2020
• Sela Tunnel = world's highest bi-lane tunnel; opened March 2024
• Nanga Parbat = "Naked Mountain" = western anchor of Himalayas
• Namcha Barwa = eastern anchor of Himalayas
• Syntaxial bends: western = Nanga Parbat, eastern = Namcha Barwa
• Indus-Tsangpo Suture Zone = line of collision between Indian and Eurasian plates
• Joshimath = built on ancient landslide zone (Mishra Commission 1976)

Mains GS1 Questions

1. "The Himalayas are geologically young and unstable. Discuss with examples of associated hazards."
2. "Explain the significance of the Trans-Himalayan ranges in India's strategic and geographical context."
3. "What are antecedent rivers? Why are Himalayan rivers considered antecedent drainage?"
4. "Critically examine the causes and impact of the Sikkim GLOF (2023). What does it reveal about climate change risks in the Himalayas?"
5. "Discuss the role of passes in the socio-economic and strategic significance of the Himalayas."

MCQ Trap Awareness

• Trap: "Kangchenjunga is entirely in India" → Partly correct — it straddles the Sikkim-Nepal border.
• Trap: "Nanda Devi is the highest peak in India" → Careful: Kangchenjunga (8,586 m, on border) is taller, but Nanda Devi (7,816 m) is the highest peak entirely within Indian territory.
• Trap: "Shiwaliks are the oldest Himalayan range" → Incorrect — they are the youngest range.
• Trap: "The Karakoram Pass is on NH1" → Incorrect — Zoji La is on NH1; Karakoram Pass is a remote high-altitude pass.
• Trap: "Atal Tunnel bypasses Zoji La" → Incorrect — it bypasses Rohtang Pass. The Zoji La Tunnel (~14.15 km, under construction, target 2028) will be the longest road tunnel in Asia when complete.
• Trap: "Saramati is in Manipur" → Incorrect — it's in Nagaland (3,826 m; highest point of Purvanchal).
• Trap: "Keibul Lamjao is the only floating national park" → Correct — it's in Manipur; say this confidently in answers.