India is a vast country which has a great diversity of relief features. Its physiographic diversity includes lofty young fold mountains, flat plains and one of the oldest plateaus of the world. The Indian islands have their own unique personality. India is generally divided into the following relief divisions.
1. The Himalayan mountain complex
2. The Indus-Ganga-Brahmaputra plain
3. The peninsular plateau
4. The coastal plains
5. The islands
1. The Himalayan mountain complex:
The Himalayan mountain ranges stretch along the northern borders of India in an east-west direction. These ranges are about 2,400 kilometres long stretching from the Indus in the west to the Brahmaputra in the east. The average width of these mountains ranges from 160 to about 400 kilometres. The Himalayan range does not consist of one range only. It is made up of a group of three ranges running parallel to each other.
- The inner Himalayas (Himadri):
This is the highest range in the Himalayan system. It is covered with snow throughout the year. The average altitude of this range exceeds 6000 metres and its average width is 25 kilometres. All the important peaks are located in this range.
- Mount Everest (8850 metres)
- Kanchenjunga (8598 metres)
- Makalu (8481 metres)
- Dhaulagiri (8172 metres)
- The middle or lesser Himalayas (Himachal):
These are located to the south of the inner or greater Himalayas and runs parallel to it in the east – west direction. Its average altitude ranges from 3700 to about 4000 kilometres. Its average width is about 80 kilometres. The important branches in this range are ‘Pir Panjal’ and ‘Dhaoladhar’ there are beautiful longitudinal valleys between these ranges and the inner Himalayas. The Kashmir and Kathmandu Valleys are outstanding examples. Hill stations such as Shimla and Darjeeling are located in this range.
- The outer Himalayas (Shiwaliks):
This is the southern-most range of the Himalayas whose height varies from 900 to 1200 metres. Its average width ranges from about 10 to 50 kilometres. Longitudinal valleys are present between the outer and middle Himalayas too. These valleys are called ‘Duns’ in the west and ‘Duars’ in the east.
- Off – shoots of the Himalayas:
The east – west axis of the Himalayas bends suddenly towards both ends. These bends are marked by the Indus gorge in the west and the Dihang gorge in the east. These two sets of off – shoots are recognised and are considered to be a part of the Himalayas.
- The north – west off – shoots:
These off – shoots consist of the mountain ranges lying beyond the Indus like the Sulaiman and Kirthar ranges.
- The north – east off – shoots :
This section lies beyond the Tsangpo – Brahmaputra gorge. This includes Indo – Myanmar hills like the Arakan Yoma and Tenasserim ranges. The Indian section of these off – shoots include the Naga, Pathai and Mizo hills.
Significance of the Himalayas:
- Climatic Influence:
These ranges play an important role in influencing the climate of India. They intercept the summer or south – west monsoon winds from the Bay of Bengal and the Arabian Sea and cause precipitation. They block the cold continental winds from central Asia too.
The Himalayas have been protecting India from invaders for a long time now. It acts as an efficient Physical barrier.
- Source of rivers:
Almost all the major rivers in India have their sources in the Himalayan ranges. Large glaciers, rain, and snowfall feed the mighty rivers of India throughout the year. The Himalayan Rivers along with their tributaries help in supporting life in northern India.
- Fertile soil:
The rivers and their tributaries carry massive quantities of alluvium when they descend from the Himalayas. This alluvium is deposited in and around the northern plain making it one of the most fertile lands in the world.