Types of Himalayas

Greater Himalayas:

1.  Highest and most continuous mountain range in the world. The Greater Himalayas are almost a contiguous range. The range has very few gaps mainly provided by the antecedent rivers. The Greater Himalayas receive less rainfall as compared to the Lesser Himalayas and the Shiwaliks. Physical weathering is pronounced. Erosion is, however, less effective over the Greater Himalayas as compared to the Lesser Himalayas. Being lofty, they have very little forest area. The Greater Himalayas are about 25 km wide with an average height above 6100 metres
2.  Crystalline rocks.

Middle Himalayas:

1.  Less in height and discontinuous. The width of the Lesser Himalayas is about 80 km with an average height of 1300-4600 m. It consists, generally, of un-fossiliferous sediments or metamorphosed crystalline.

Outer Himalayas:

1. Upliftment of the foothills of the Himalayas. The Shiwaliks extend from Jammu Division of Jammu and Kashmir State to Assam. In width, Shiwaliks vary from 8 km in the east to 45 km in the west with an average elevation of about 900 – 1500 m above sea level. It is not a continuous range. It is broader in the west and narrows down In the east. Between the Shiwaliks and the Lesser Himalayas are longitudinal valleys called Doons / Duns.
2. They are created due to the alluvial deposit of the Himalayan rivers.

Structure of Himalayas:

1.  The middle bend is convex shape.
2.  Second sharp bend is towards southern end.
3.  Western bend towards Nanga Parbat and eastern towards Namcha Barwa.
4.  Northern side rests against Tibetan plateau and southern side is covered with snow. Gentle slope on northern side and steep slope on southern side.
5.  The mountains don’t act as a water divide but allow rivers to cut across. The rate of erosion by rivers is greater than the rate of upliftment of Himalayas.

                                          TABLE 1: EASTERN AND WESTERN HIMALAYAS

Region – wise division of Himalayas

The Himalayas are divided into five regions:

1.  Kashmir Himalayas
2. Karakoram, Ladakh, Zanskar, Pir Panjal and Dhauladhar are the ranges from north to south in that order. It has the largest number of glaciers in India.
3. Karewa formation – clay, sands from old fertile lands. Surrounded by the Greater Himalayas and the Lesser Himalayas is the Kashmir Valley. Having a height of 1585 m above the sea-level, the total area of the Kashmir Valley is about 4920 sq km. It is a structural longitudinal ‘Dun’. A special feature of the the Vale of Kashmir is the Karewa (lacustrine) deposits consisting of silt, sand and clay. These karewas are mainly devoted to the cultivation of saffron and have orchards of apple, peach, almond, walnut and apricot. Kashmir Himalayas are characterised by high snow covered peaks, deep valleys, interlocked spurs and high mountain passes.
4.  Lake Wular – largest freshwater lake of India located in Kashmir.

2.  Kumaon Himalayas:The Kumaon Himalayas are connected to Tibet by a number of passes.
3. Garhwal and Kumaon hills from west to east.
4. Source of Ganga and Yamuna. Located in Uttarakhand.
5.  Nepal Himalayas
6. Tallest section of the Himalayas. .
7.  Sikkim Himalayas: The highest peaks of the world like Mt. Everest (8850 m), Kanchenjunga {8598 m}, Makalu (8481 m), Dhaulagiri (8172 m), Annapurna (8078 m), Manaslu (8154 m) and Gosainath (8014 m) are situated in this part of the Himalayas. It has very few passes. The passes of Nathu-La and Jelep La (4538 min Sikkim) connect Gangtok (Sikkim) with Lhasa (Tibet, China).
8.  Assam HimalayasOn the southern border of Arunachal Pradesh, the Himalayas take a southerly turn and the ranges are arranged in a north-south direction. Passing through the states of Arunachal Pradesh (Tirap Division) Nagaland, Marripur, Trip ura, and Mizoram, the Himalayas are locally known as Purvachal. The Purvanchal is joined by the Meghalaya Plateau in the west. The extension of the Myanmar mountain chain continues southward up to Andaman and Nicobar Islands and even up to the Archipelago of Indonesia.

Himalaya range isn’t stable like western ghats

Debris, avalanches, landslides occur frequently in the Himalayas as they are techtnically active, made up of sedimentary, unconsolidated or semi consolidated rocks.

They have steep slopes.

Nilgiris slightly techtonically stable and have have hard rocks so land slides are less frequent. However direct rockfall is seen due to steep slopes, heavy rains and mechanical weathering due to temperature and escarpments.

Dun:

When rivers are obstructed by mountains they spread out to form lakes. The lakes dry up when the rivers find paths through the mountains. These dried up lakes are called “duns”. They are found between great and middle Himalayas .

Importance of Himalayas: 

1. Prevents cold Siberian winds from entering into India.
2. Himalayas are responsible for rainfall in north east. Also without them there would be no Tibet plateau and India would have been a desert.
3. They split the sub tropical jet streams into two bringing winter rain to India.
4. Source of perennial rivers.
5. Great forest and mineral wealth

The Syntaxial Bends of the Himalayas

• • The general east-west trend of the Himalayas terminates suddenly at its western and eastern extremities and the ranges are sharply bent southward in deep knee-bend turns which are called syntaxial bends.

• • The western syntaxial bend is near Nanga Prabat where the Indus has cut a deep gorge.
  • There is a similar hair-pin bend in Arunachal Pradesh where the mountains take a sharp bend from the eastern to southern direction after crossing the Brahmaputra river.