- It is a young fold mountain
- Its formation started in 70 million years before present ( aravalis and Eastern Ghats are 700 million years old)
- formed by collision of Indian and Eurasian plate
- Rains are mostly orographic
- It acts as a barrier
- Blocks Siberian cold winds from the north
- Blocks monsoon winds from the south
- Hence 60% of all life from South of Himalayas are endemic to our country.
Three main ranges of Himalayas
- Greater Himalayas / Himadri 6000m
- Middle Himalayas/ Himachal
- Shivalik 1000m - 2000m
4 phases in the formation of Himalayas.
1. 70 million years before present
Indian Plate breaks up with gondwanaland. Moves northwards towards Eurasian plate. Tethys sea starts contracting.
2. 40 to 50 million years before present
Greater Himalayas is formed. Thethys sea subducts. Accretion on Eurasian plate. Hence some part is volcanic. Karakoram, Ladakh, and Zaskar ranges are formed. It is Marine in origin.
3. 20 - 30 million years before present
Middle Himalayas is formed . Two plates actually collided. It is a strong force. Don't have symmetric forces. Therefore has asymmetrical, recumbent and Nappe structures. It is Marine in origin.
4. 2 million years before present
Shivaliks were formed. It is fluvial in origin. Many Alluvial fans combined to form shivaliks. So shivaliks differ in structure and orogeny.
Features of Himalayas
1. Double crust
Tibetian side - Eurasian plate, greater height, greater accumulation of snow, Less steeper than Southern side.
Indian side - lesser height, steeper than Northern side, less accumulation of snow, snowfall is Greater on Indian side.
2. Syntaxial bend
Western most part - Nanga Parbat.
Sharp hair pin turn towards south.
Easternmost part - Namcha Barwa
3. Extension of Himalayas
Towards west - Sulaiman and kirthar ranges.
Towards east - Arakan yoma and pegu yoma.
4. Eastern Himalayas vs Western Himalayas
Eastern Himalayas - steep, narrow, higher. Higher snowline. Wetter.
Western Himalayas - less steep, less narrower, lower than that of eastern Himalayas. Lower snowline. Less wet.
Major faults of Himalayas
- Indus tsangpo suture zone
- Main Central thrust/ fault
- Main boundary thrust/ fault
- Himalayan frontal fault
Himalayas have displaced roots.