India is characterized by great diversity in its physical features. On the basis of physiography, the country is divided in to four major physical divisions. They are:

1. The Northern Mountains 

2. The Northern Plains 

3. The Peninsular Plateau 

4. The Coastal Plains and Islands

The Himalayas: This is loftiest and snow covered mountains in the world. The area occupied by the Himalayas was earlier a part of ‘Tethys Sea’. The formation of this mountain is by tectonic forces of Gondawana land Angara land masses. It is situated to the north of the Indus and Ganga and the Brahmaputra plains.. The slopes of the Himalayas are gentle towards the north and steep towards south.

The Himalayas have distinct characteristics of high relief, snow covered peaks, complex geographical structures, parallel separated by deep valleys and rich temperate vegetation.The Himalayas are classified into three parallel ranges based on altitude and latitude.

The Great Himalayas or Himadri The lesser Himalayas or Himachal The Outer Himalayas or Siwaliks.

a. The Great Himalayas or Himadri: These are the inner most loftiest and continuous ranges of mountains. The average height of the Great Himalayas is 6200 m and the width varies between 120 and 190 km. The important peaks of great Himalayas in India are, Kanchenjunga-8598m in Sikkim, Nanga Prabat-8126m, Nandadevi, Badrinath, Karmet, Trishuletc.

b. The lesser Himalayas or Himachal: These ranges are also known as Inner Himalayas or Himachal ranges. It is situated between great Himalayas inn the north and Outer Himalayas or Siwaliks in the south. Its average height is around 1500-4500m and the width is about 60 to 80 km. These are very rugged and complex ranges due to erosion by rivers. The important ranges in Lesser Himalayas are Pirpanjal, Dhaul Dhar and nag- tiba etc. The important Hill stations are Shimla, Musooire, Ranikeht, Nainital, Almora, Chakrata, Darjeeling etc. Kulu valley, Kangra valley, Spiti valley are the famous valleys of Himachal.

c. The Outer Himalayas or Siwaliks: These are the outer most ranges situated to the south of Lesser Himalayas, known as Siwaliks. The Siwaliks extend from Jammu & Kashmir in the North West to Arunachal Pradesh in east. The average height of this range is around 600-1500m and its width varies between 15-5Qklm. The siwaliks are formed from the sediments brought down by the rivers of lesser, and Greater Himalayas.

There are flat floored structure valleys between Siwaliks and Lesser Himalayas, Known as Siwaliks. The Siwaliks extend from Jammu&Kashmir in the North West to Arunchal Pradesh in east.