Physical divisions, weathering and erosion, and the northern mountains
India has six physical divisions. In the north, the young fold Himalayas run in three parallel ranges: Himadri, Himachal and Shiwaliks.
Six physical divisions
- Topography means the natural features of a place: its mountains, plains, valleys and so on. Terrain is an area of land with one type of feature.
- India's topography differs because its rocks were formed in different geological periods, and because weathering, erosion and deposition have shaped them.
- On this basis India has six divisions. They are (1) the Northern Mountains, (2) the Northern Plains, (3) the Peninsular Plateau, (4) the Indian Desert, (5) the Coastal Plains, (6) the Islands.
Weathering and erosion
Where the stream slows down, it drops its load. This is deposition, and it builds new land such as plains and deltas.
The Himalayas at a glance
- The Northern Mountains have three groups: the Himalayas, the Trans-Himalayas and the Purvanchal hills.
- The Himalayas are young fold mountains: rock layers were folded up fairly recently in the Earth's history. They are the highest mountains in the world.
- They run west to east for about 2,500 km, from the Indus to the Brahmaputra, along India's northern border.
- They are about 400 km wide in the west and about 150 km wide in the east.
- They act as a natural barrier: extreme cold, snow and rugged land made entry into India across them difficult.
- Key words: a range is a long chain of mountains; a peak is the highest point; a pass is a natural gap used as a route; a valley is low land between hills; a dun is a long valley between the Shiwaliks and the Himachal.
The three parallel ranges of the Himalayas
| Range | Height and width | Main features and examples |
|---|---|---|
| Greater Himalayas or Himadri (northernmost) | Average 6,000 m; 120 to 190 km wide | Most continuous range, snow-bound, with many glaciers. Peaks above 8,000 m: Everest, Kanchenjunga, Makalu, Dhaulagiri, Nanga Parbat. Passes: Bara Lacha La, Shipki La, Nathu La, Zoji La, Bomdi La. The Ganga and Yamuna rise here. |
| Lesser Himalayas or Himachal (middle) | 1,000 to 4,500 m; about 50 km wide | Pir Panjal, Dhaula Dhar and Mahabharat ranges. Hill stations: Shimla, Mussoorie, Nainital, Dalhousie, Chakrata, Darjeeling. Valleys: Kashmir, Kullu, Kangra. |
| Outer Himalayas or Shiwaliks (southernmost) | 900 to 1,100 m; 10 to 50 km wide | Low outer hills such as the Jammu hills. Duns lie between them and the Himachal: Dehra Dun, Kotli Dun, Patli Dun. |
Trans-Himalayas and Purvanchal
- Trans-Himalayas: north of the Greater Himalayas and parallel to it lies the Zaskar range. North of the Zaskar lies the Ladakh range. The Indus flows between them.
- The Karakoram range lies in the extreme north. Its peak K2 (8,611 m) is the second highest in the world.
- Purvanchal: the eastern hills along the border with Myanmar, namely the Mishmi, Patkai, Naga and Mizo hills.
- The Meghalaya plateau, with the Garo, Khasi and Jaintia hills, is counted with them.
On the map
- Karakoram range: the extreme north of India, in Ladakh, north of the Ladakh range; K2 (8,611 m) stands here.
- Ladakh and Zaskar ranges: in Ladakh, running north-west to south-east, with the Indus between them.
- Nanda Devi (7,817 m): in Uttarakhand, in the central Himalayas.
- Kanchenjunga (8,598 m): on the Sikkim-Nepal border; India's highest Himalayan peak.
- Mt Everest (8,848 m): in Nepal, near its border with Tibet, north of eastern Bihar. Mark it outside India.
- Pir Panjal range: Lesser Himalayas in Jammu and Kashmir, south-west of the Kashmir valley.
- Shimla: a hill station of the Himachal (Lesser or Middle Himalayas), in Himachal Pradesh.
- Shiwalik hills: the outermost foothills along the northern edge of the plains, from Jammu to Uttarakhand.
- Dehra Dun: a dun valley in Uttarakhand, between the Shiwaliks and the Himachal.
- Garo, Khasi and Jaintia hills: west to east across Meghalaya, south of the Brahmaputra valley.
- Patkai, Naga and Mizo hills: along the Myanmar border, from Arunachal Pradesh south to Mizoram.
Hill stations of the Himachal range, such as Shimla, Mussoorie and Darjeeling, draw tourists every summer. Glaciers of the Himadri feed the Ganga and Yamuna, which water farms and cities in the plains.
2 marks: “Distinguish between weathering and erosion.” Weathering is the breaking down of rocks where they lie by physical, chemical and biological processes. Erosion is the carrying away of the broken material by rivers, wind and glaciers. Weathering involves no transport; erosion does.
3 marks: “Name the three parallel ranges of the Himalayas and give one feature of each.” Himadri: highest, average 6,000 m, snow-bound, with peaks like Kanchenjunga. Himachal: 1,000 to 4,500 m, with hill stations like Shimla and valleys like Kullu. Shiwaliks: outermost, 900 to 1,100 m, with duns like Dehra Dun.
1 marks: “Name India's highest Himalayan peak and the state on whose border it stands.” Kanchenjunga (8,598 m), on the border of Sikkim and Nepal.
Walk south from Tibet and you step down: Himadri (snow) to Himachal (hill stations) to Shiwalik (small hills and duns).