Physiographic Divisions of Himalayas :-
- For a systematic study of the Physiography and relief, the Himalayas may be devided into the following four division from north to south.
- The Trans - Himalayas
- The Greater Himalayas
- The Lesser Himalayas
- The Shiwaliks or the outer Himalayas.
1. The Trans - Himalayas :- The Trans - Himalayas are about 40 km wide. They contain the Tethys sediment. The sediment rocks of this region contains fossils bearing maring seximese which are underlain by "Teritary Granite". It has partly metamporphosed sediment and constitutes the core of the Himalayas axis.
2. The Greater Himalayas :- The greater Himalayan rise abruptly like a wall North of the lesser Himalayas. The MCT separate the Greater Himalayas from the lesser Himalayas. The greater Himalayas are about 25 km wide with an average height above 6100 km (Wadia, D.N). Almost all the lofty peaks of the Himalayas. Mr. Everest, Kanchanjunga, Nanga - Parbhat, Gasherbrum, Manaslu, Dhaulagiri, Ananpurna, Gosainthan, Cho- Chu, Nanda Devi, Kamet, Badrinath, Nanda Devi etc. Lie in this zone. The greater Himalayas are composed of Crystalline, igneious or metamorphic rocks (granite, schists and neiss). The highest peak of the mount Everest (8848 m) lies here. Mount Everest is also called Sagarmatha or Chong - lunema by the Tibetans.
3. The Lesser Himalayas :- The width of the lesser Himalayas is about 80 km with an average height of 1300 - 4600 m. The main rocks are slate, limestone and quartzites. Know by various local names (I) Pir Panjal Jammu and Kashmir (ii) Dhola Dhar Himachal Pradesh (iii) Mussorie and Nag tibba Uttarakhand (iv) Mahabharta Lekh in Uttarakhand. Most major hill station lie in the lesser Himalayas Viz, Shimla, Ranikhet, Mussorie, Nainital etc .
4. The Shiwaliks or the outer Himalayas / Sub Himalayas :- The Shiwaliks extends from Jammu and Kashmir state of Assam. In width, Shiwaliks vary from 8 km in the East to 45 km in the West with an average elevations of about 900 - 1500 m above sea levels. It is not a continuous range. It is broader in the West and narrows down in the East. Between the Shiwaliks and the kessrl Himalayas are longitudinal valleys called Doons / Duns.
Longitudinal Division of the Himalayas :-
- The Himalayas have also divided by Sir. S. Burrard into four division, namely (I) The Punjab Himalayas (ii) The Kumaon Himalayas (iii) The Nepal Himalayas (iv) The Assam Himalayas.
The Great Plains of India :-
- The great plains of India lies to the South of the Shiwaliks separated by the Himalayas Front fault (HFF ). It is a transitional zone between the Himalayas of the North and Penisular India of the South.
- It is an aggrational plains formed by the alluvial deposit of the Indus, Ganga, Brahmaputra and their tributaries. The plains strectches for about 2400 km from West to East. It has varying width; 90- 100 km in Assam, 160 km near Rajmahal (Jharkhand), 200 km in Bihar, 280 km near Allahabad and 500 km in Punjab. In general the width of the plains increase from East to west.
- The Great plains of India largely of alluvial deposit brought down by the rivers originating in the Himalayas and the Penisular regions. The Himalayas has maximum depth of over 8000 m has been reached near Ambala, Yamunanagar and Jagadhri (Haryana).
