A glacier is a body of ice that originates on land by the recrystallization of snow under definite condition : it needs :
1. a distinct area where more snow or ice usually accumulates than what melts – the accumulation zone
2. another distinct area where snow or ice usually melts or wastes than what accumulates – the ablation zone and
3. a snow transfer (by creep) of the ice mass from the first region to the second.
In accumulation zone, even at the peak of summer the temperature is too low to melt all the snow and even some ice. The line separating accumulation zone and ablation zone is called the equilibrium line. The terminus of the glacier or the snow represents the lowest point, where ice can survive. Sometimes water flows down from the snow of the glacier to form a lake down stream.
Glaciers vary widely in forms and characteristics. The major morphological types include
(i) the cliff and the cirque glaciers
(ii) the valley glaciers and
(iii) the continental ice sheets
The glaciers in the Himalayas fall in the category of the temperate glaciers. In the temperate glaciers, the temperatures are not much below the melting point of ice, except in winter, when the top layer may be frozen to a depths of ten metres. Besides direct precipitation, in the Himalayas, avalanches also form an important source of snow deposition because of the steepness of the hills.
The Himalayas which have nearly 15,000 glaciers – are one of the largest continental areas under ice. It is estimated that about 33,000 square kilometers constituting about 17 percent of the Himalayas and 16,000 square kilometers amounting to nearly 37 percent of the Karakoram are ice-clad.
Glaciers in local language are known as “Shigri”. There are four major concentration of glaciers in Himachal Pradesh; namely
(i) Bara Banghal, lying amidst Kullu, Kangra, Chamba and Lahaul Valleys, feeding the river Ravi
(ii) Near the tri-junction of Kullu, Spiti and Kinnaur ; feeding the tributaries of the Beas and Satluj and
(iii) in the zone of Lahaul – Spiti and Kullu valleys, feeding glacial tributaries of the Beas river
Bara Shigri : It is the largest glacier in Himachal Pradesh, located in the Chandra valley of Lahaul and feeding the river Chenab. It is about 3 km wide and 25 km long. It is tenated in a cirque on the middle slopes of the main Himalayan range. High mountains surround Bara Shigri glacier from three sides. The other prominent glacier of Chandra valley in Lahaul are – Chhota Shigri, Pacha, Kulti, Shipting, Ding Karmo, Tapn, Gyephang, Shili, Bolunag and Shamundri.
Bhadal Glacier : It is located on the South-Western slopes of the Pir Panjal range in the Bara Banghal area of Kangra district of Himachal Pradesh. The river Bhadal is fed by this glacier, which is one of main tributaries of the river Ravi. The surface of this glacier is strewn with boulders and other glacier deposits.
Chandra Glacier : It is located on the slopes of the main Himalaya in the Lahaul-Spiti district of Himachal Pradesh. This glacier is responsible for forming Chanderlal lake and has originally separated from Bara Shigri glacier. It feeds the river Chandra, which along with Bhaga forms the Chenab.
Bhaga Glacier : It is located on the slopes of the main Himalayan range in Lahaul area of Himachal Pradesh. The river Bhaga originates from this glacier. High snow clad peaks surround this glacier on all sides. Bhaga glacier can be approached via Koksar and Tandi in Lahaul Spiti district. It is 25 km long.
Chandra Nahan : It is located on the South-Eastern slopes of the main Himalaya in the area to the North-west of Rohru in Himachal Pradesh. The river Pabbar is fed by this glacier. The glacier is surrounded by high rising peaks, having elevations about 6,000 meters.
The lady of Keylong : This glacier is situated at an altitude of about 6061 mts which can be seen from Keylong and is vary popular among visitors. It was named so by ‘Lady Elashaingday’ about a century ago during British Raj. It remains snow covered round the year. But in the middle, there is seen a dark bare patch that looks like the figure of a woman, walking with a load on her back. Geological Survey of India has also recorded it as the ‘Lady of Keyong’.
Gora Glacier : This glacier is tenanted on the South-facing slopes of the main Himalayan range of Himachal Pradesh. Gora glacier has receded in the recent past due to a negative mass balance.
Mukkila Glacier : The Mukkila glacier of Bhaga valley is situated at the height of about 6478 mts.