Sunday, August 17, 2008

The Great Himalayas

The Great Himalaya

Himalayas start from Pamir Knot (Middle Asia) and continues in South Eastern direction, first in the northern India in Jammu and Kashmir where the world's second largest peak Karakorum lies then in Nepal where world's highest peak Mt. Everest lies then in Myanmar as Arakom Yoma. Himalayas is divided into three branches.
Greater Himalayas: It is also known as Himadari, its average height is 6000-7000m. Many large peaks like Karakorum, in India and Mt. Everest, in Nepal also lies in the greater Himalayas. Many large glaciers like Gangotari source of water for river Ganga, Yamnotari source of water for Yamuna is also present
Lesser Himalayas: It is also known as Himachal with an average height of 4000-5000m. Many beautiful hill station like Shimla, Darjeeling, Paragpur, Chamba, Chitkul, Dalhousie, Dharamsala, Kangra, Kullu, Lahaul Spiti, Mandi and Solan are also part of these ranges.
Outer Himalayas: It is also known as Shivalik, average height is 1000-1250m. It is not a continuous range and is broken down into many small ranges. It merges with the lesser Himalayas in the east and is made up of loose rock and soil hence it is prone to earthquake and landslides, it then extends eastward as Puravanchal range it includes various ranges such as Naga, Karo, Lushai Hills, Jaintia etc. Many passes like Zoji La, Nathu La, Shipki La, Bomdi La also lie in the outer Himalaya's.

The Himalaya is the youngest mountain ranges on the planet. According to the modern theory of plate tectonics, their formation is a result of a continental collision or orogeny along the convergent boundary between the Indo-Australian Plate and the Eurasian Plate. The collision began in the Upper Cretaceous period about 70 million years ago, when the north-moving Indo-Australian Plate, moving at about 15 cm/year, collided with the Eurasian Plate. By about 50 million years ago this fast moving Indo-Australian plate had completely closed the Tethys Ocean, the existence of which has been determined by sedimentary rocks settled on the ocean floor and the volcanoes that fringed its edges. Since these sediments were light, they crumpled into mountain ranges rather than sinking to the floor. The Indo-Australian plate continues to be driven horizontally below the Tibetan plateau, which forces the plateau to move upwards. The Arakan Yoma highlands in Myanmar and the Andaman and Nicobar Islands in the Bay of Bengal were also formed as a result of this collision.

The Indo-Australian plate is still moving at 67 mm/year, and over the next 10 million years it will travel about 1,500 km into Asia. About 20 mm/year of the India-Asia convergence is absorbed by thrusting along the Himalaya southern front. This leads to the Himalayas rising by about 5 mm/year, making them geologically active. The movement of the Indian plate into the Asian plate also makes this region seismically active, leading to earthquakes from time to time. 

The Himalaya region is dotted with hundreds of LAKES. Most lakes are found at altitudes of less than 5,000 m, with the size of the lakes diminishing with altitude. The largest lake is the Pangong Tso, which is spread across the border between India and Tibet. It is situated at an altitude of 4,600 m, and is 8 km wide and nearly 134 km long. A notable high (but not the highest) lake is the Gurudogmar in North Sikkim at an altitude of 5,148 m (16,890 ft) (altitude source: SRTM). Other major lakes include the Tsongmo lake, near the Indo-China border in Sikkim(India), and Tilicho lake in Nepal in the Annapurna massif, a large lake in an area that was closed to outsiders until recently.

The mountain lakes are known to geographers as tarns if they are caused by glacial activity. Tarns are found mostly in the upper reaches of the Himalaya, above 5,500 metres. 

1 comment:

Miss Mansi said...

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