A valley-type glacier

Print edition : March 31, 2001

THE Gangotri is the second largest Himalayan glacier after Siachen. The width of this 30.2-km-long glacier, whose head at its highest point is called Chaukhamba, varies from 0.5 km to 2.5 km. It is the source of the Bhagirathi which originates at Gaumukh , the snout. The Bhagirathi joins the Alaknanda, fed by the glacier Satopan, downstream to become the Ganga. It is a valley-type glacier, situated in the Uttarkashi district of Garhwal Himalayas in Uttaranchal State.

The interesting thing about Gangotri's topography is that at its source the river flows north west. The glacier extends in height from 4,120 to 7,000 m above sea level (masl). It has three main tributaries: Raktvarn (15.9 km), Chaturangi (22.45 km) and Kirti(11.05 km) and more than 18 other tributary glaciers that are transverse to the main trunk. The total glacierised area of the catchment is 258.56 sq km, of which the Gangotri system accounts for 109.03 sq km, followed by Chaturangi (72.91 sq km), Ra ktavarn (45.34 sq km) and Kirti (31.28 sq km). The total ice cover of the catchment is 200 sq km and the total ice in the glacierised area is about 20 cu km. The Gaumukh is now at 4,120 masl and it is located at the northernmost end of the glacier. Subte rranean channels below the glacier are also known to feed the Bhagirathi at Gaumukh. As a result of the retreat of the Gangotri, the Meru glacier, which used to feed the Gangotri just before the snout, now meets the Bhagirathi downstream of Gaumukh.

The Gangotri had in the past extended up to Sukhi, below Jhala, which is 40.5 km downstream of Gaumukh in the Bhagirathi valley. This assumption is based on observations on moraines at an altitude of about 2,300 masl. This is the oldest terminal moraine of the Gangotri glacier and its position probably represents the position of the snout during Pleistocene. This, it is believed, resulted in the expansion of the glacierised area in the form of a long valley glacier system covering a minimum area of 685 sq km during what is known as the Bhagirathi glacial stage (about 100,000 years ago). The remnants of lateral moraines can now be seen on both sides of the valley up to Gangotri town, which is 18 km downstream of Gaumukh.

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