The Himalayas: Formation, Parallel Ranges, Regional Divisions, Passes and Significance for India (UPSC Notes + PYQs)

Background: the youngest great mountains

The Himalaya stretch for about 2,400 km in an arc from the Indus gorge in the west to the Brahmaputra gorge in the east, with a width of 150 to 400 km. They include the world’s highest peaks and are among the youngest mountains on Earth, still rising by a few millimetres a year. For India they are more than a border. They are the source of perennial rivers like the Ganga, Yamuna, Indus and Brahmaputra, which feed the plains where hundreds of millions live. They block cold winds from Central Asia and force the monsoon winds to shed rain over the subcontinent. They hold forests, glaciers and a rich variety of plants and animals, and are home to many communities with distinct cultures. Their geology also makes them prone to earthquakes, landslides and floods.

Formation

The Tethys Sea between Gondwana and Angaraland closed as the Indian plate moved north. Sediments folded upward. The plate still moves north by roughly 5 cm a year, which is why the region is seismically active and the mountains are still rising.

Three parallel ranges

North of the Himadri lie the Trans-Himalaya: Karakoram, Ladakh and Zaskar ranges.

West-to-east divisions (by rivers)

• Punjab Himalaya: between the Indus and Sutlej.
• Kumaon Himalaya: between the Sutlej and Kali.
• Nepal Himalaya: between the Kali and Teesta.
• Assam Himalaya: between the Teesta and Dihang (Brahmaputra).

Beyond the Dihang gorge, the Purvanchal hills (Patkai, Naga, Mizo, Garo-Khasi-Jaintia is an extension of the plateau) curve south.

Significance

• Climatic barrier against cold Central Asian winds; forces monsoon rainfall.
• Source of perennial rivers (Indus, Ganga, Brahmaputra) fed by glaciers.
• Hydropower, forests, medicinal plants, tourism and pilgrimage.
• Strategic frontier with China and Pakistan; key passes like Zoji La, Shipki La, Nathu La, Bomdi La.

The ranges in detail

Between the ranges lie longitudinal valleys. The Kashmir valley lies between the Pir Panjal and the Greater Himalaya, while flat ‘duns’ such as Dehradun, Kotli Dun and Patli Dun lie between the Lesser Himalaya and the Shiwaliks.

A fragile system

Young geology, steep slopes and heavy rain make the region prone to landslides, glacial lake outburst floods (South Lhonak, 2023) and earthquakes. Joshimath (2023) showed the cost of building without carrying-capacity studies. The National Mission for Sustaining the Himalayan Ecosystem (NMSHE) is one of the eight missions under the NAPCC.

Climate role of the Himalaya

The Himalaya act as a climatic wall. In winter they stop the cold, dry winds of Central Asia from entering the plains, which keeps north India warmer than places at similar latitudes. In summer they force moisture-laden monsoon winds to rise, cool and shed rain, especially on the eastern side, which is why Meghalaya and the north-eastern hills receive some of the heaviest rainfall in the world. The Tibetan plateau, heated in summer, helps set up the low pressure that pulls the monsoon in, and the high-altitude westerly jet stream shifts north of the Himalaya when the monsoon arrives. Glaciers act as water towers, releasing meltwater in the dry season. This is why scientists call the region the Third Pole.

Passes of the Himalaya

Why the Himalaya are fragile

Young mountains have weak, fractured rocks and steep slopes. The region lies in seismic zones IV and V, and major thrust faults run along the ranges. Heavy rain, cloudbursts and glacier melt trigger landslides and flash floods, as seen in Kedarnath (2013) and Chamoli (2021). Glacial lakes can burst and send walls of water downstream, a hazard called a glacial lake outburst flood. Human activity adds stress: road cutting without slope protection, tunnels and dams, deforestation, unplanned towns on slopes and heavy tourism. The sinking of Joshimath in Uttarakhand in 2023 drew attention to building on old landslide material. Responses include carrying capacity studies for hill towns, strict zoning, slope stabilisation, early warning for glacial lakes, and the National Mission for Sustaining the Himalayan Ecosystem under the National Action Plan on Climate Change.

Writing on the Himalaya in Mains

Structure answers around formation, divisions, significance and fragility. Use a north-south cross-section sketch showing the four ranges and the duns, and a map with the rivers that divide the range into Punjab, Kumaon, Nepal and Assam Himalaya. Close with sustainable mountain development rather than blanket opposition to all infrastructure.

Himalayas: UPSC angle

Himalayas UPSC PYQs (Prelims)

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Mains PYQs on this topic

No UPSC Mains question from 2023-2026 is directly on this topic. Older papers (2013-2022) will be added as the Mains bank grows.

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