The Himalayas and Northern Mountains
NCERT Class 9 - Contemporary India I, Chapter 2 • NCERT Class 11 - India Physical Environment
The Himalayas and Northern Mountains
The Himalayas are young fold mountains formed by the collision of the Indian and Eurasian plates, and they are still rising. They run about 2,400 kilometres in an arc from the Indus gorge in the west to the Brahmaputra gorge in the east.
The three parallel ranges
| Range | Height and character | Features |
|---|---|---|
| Himadri or Greater Himalaya | The highest and most continuous range, averaging about 6,000 metres | Highest peaks, perpetual snow, glaciers, granite core |
| Himachal or Lesser Himalaya | Between about 3,700 and 4,500 metres, highly folded | Pir Panjal is the longest range; hill stations and famous valleys |
| Shiwalik or Outer Himalaya | Between about 900 and 1,100 metres, the lowest range | Made of unconsolidated sediment; flat valleys called duns |
- The Greater Himalaya contains the highest peaks of the world, including Kanchenjunga and Nanda Devi within or on India's borders.
- Famous valleys of the Lesser Himalaya include the Kashmir, Kangra and Kullu valleys, and its hill stations include Shimla, Mussoorie, Nainital and Darjeeling.
- The Shiwalik is composed of sediment brought down by rivers from the rising ranges; the longitudinal valleys between the Shiwalik and the Lesser Himalaya are called duns, such as Dehra Dun, Kotli Dun and Patli Dun.
- The Kashmir valley lies between the Greater Himalaya and the Pir Panjal, and the Kashmir Himalaya is known for its karewas, thick glacial deposits on which saffron is grown.
Regional divisions from west to east
- Punjab Himalaya - between the Indus and the Satluj, also called the Kashmir and Himachal Himalaya.
- Kumaon Himalaya - between the Satluj and the Kali.
- Nepal Himalaya - between the Kali and the Teesta, containing the highest section.
- Assam Himalaya - between the Teesta and the Dihang gorge.
- Purvanchal or the Eastern Hills - the Himalayas bend sharply south beyond the Dihang, forming the Patkai Bum, Naga, Manipur and Mizo or Lushai hills along the border with Myanmar. These hills are lower and covered with dense forest.
Important passes
| Pass | State or region |
|---|---|
| Karakoram Pass | Ladakh, the highest pass on the old route to Central Asia |
| Zoji La | Ladakh, connects Srinagar with Leh |
| Banihal | Jammu region, on the route to the Kashmir valley |
| Shipki La | Himachal Pradesh, on the Satluj route to Tibet |
| Rohtang | Himachal Pradesh, leading to Lahaul and Spiti |
| Lipulekh, Mana and Niti | Uttarakhand, on the traditional routes to Tibet |
| Nathu La and Jelep La | Sikkim, on the route to Tibet |
| Bomdi La | Arunachal Pradesh |
Significance of the Himalayas
- They act as a climatic barrier, blocking the cold winds of Central Asia and forcing the monsoon to shed its rain over the subcontinent.
- They are the source of the great perennial rivers, fed by snow and glaciers as well as rain.
- They are a defence barrier, historically limiting invasion routes to a few passes.
- Their forests, minerals, hydroelectric potential, tourism and pilgrimage give them great economic value.
- Because they are young and unstable, the region is highly prone to earthquakes and landslides.
हिंदी संकेत: दून शिवालिक और लघु हिमालय के बीच की समतल घाटियां हैं - देहरादून सबसे प्रसिद्ध उदाहरण है। यह शब्द बार-बार पूछा जाता है।
Exam me kaise aata hai
Match-the-following on pass and state is almost guaranteed. Factual questions ask the average height of each range, which range holds the duns, and the four regional divisions. Application questions ask why Himalayan rivers are perennial.
UPSC / State PSC ke liye
Link the geology to the hazard - the Himalayas are young, tectonically active and made partly of loose sediment, so earthquakes, landslides and flash floods are structural features of the region, not accidents. Road building and hydropower construction on such slopes therefore need especially careful appraisal.
Yahan confuse hote hain
✗ The Shiwalik is the highest Himalayan range | ✓ The Himadri or Greater Himalaya is highest; Shiwalik is lowest
✗ Duns lie between the Greater and Lesser Himalaya | ✓ They lie between the Shiwalik and the Lesser Himalaya
✗ The Purvanchal hills are part of the Western Ghats | ✓ They are the eastward continuation of the Himalayas
Ek nazar me
- The Himalayas are young fold mountains formed by plate collision and are still rising.
- Three ranges - Himadri or Greater, Himachal or Lesser, and Shiwalik or Outer.
- Pir Panjal is the longest range of the Lesser Himalaya; duns lie between Shiwalik and Lesser Himalaya.
- Regional divisions - Punjab, Kumaon, Nepal and Assam Himalaya.
- Purvanchal includes the Patkai Bum, Naga, Manipur and Mizo hills.
- Passes - Karakoram and Zoji La in Ladakh, Shipki La and Rohtang in Himachal, Nathu La in Sikkim.
- The Himalayas are a climatic and defence barrier and the source of perennial rivers.