What is the insignificance of Himalayas?
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Answer:
The Himalayas constitutes an imposing crescent-shaped mountain range extending for over 2500 km from the south of the Indus Valley beyond Nanga Parbat in the west to Namcha Barwa in the east (Fig. 17.1). The range varies in width from 350 km in the west to 150 km in the east. The majestic mountain chain showing prominent southward convexity stands like a wall bordering the entire northern margin of the Indian Subcontinent.
Fig. 17.1
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Fig. 17.1. Google Satellite Imagery showing geomorphic traits of the Himalayas and Tibetan Plateau region.
Geomorphologically, the most unique feature of the Himalayas is the soaring height it attained, crowned with many of the Earth's premier snow-covered peaks, including 10 of the 14 over 8000 m peaks in the world (Fig. 17.2).
Fig. 17.2
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Fig. 17.2. Kanchenjungha, the third highest mountain peak in the world, is one of the crowning glories of the Himalayas.
An important geomorphotectonic character of the Himalayas is the sharp bending of the Himalayas and the associated mountain ranges, which at the western end join with the Sulaiman and Kirthar Ranges in the southwestern end. There is a similar sharp bending at the eastern end, where the mountain range joins the north-trending Indo-Myanmar Range, represented by the Naga Hills and the Arakan Yoma. These two sharp bends on either side of the mountain range are popularly known as the ‘Syntaxial bends’ of the Himalayan Mountain Range. The most of the high (over 8000m) peaks in the world are located in different parts of the Himalayas but mostly in the central part.
The geophysical characteristics of the Himalayas are as unique as the geomorphotectonic traits of the mountain range. The most distinctive feature of the Himalayas is the crustal thickness, which increases from about 35 to 40 km in the Indus-Ganga-Brahmaputra Plains to between 65 and 80 km over the Higher Himalayas (Qureshy, 1969). The thickness of the continental Crust underlying the Himalayas is reflected in the strong negative gravity anomaly pattern between >−150 and >−350 mGal along the entire length of the mountain belt (Qureshy and Kumar, 1992). The increasing crustal thickness is reflected in the dip of the MOHO, which is estimated to be 7–8°N under the Sub-Himalayas to over 15° further north. A complex architecture of the MOHO with dipping and overlapping segments indicates lithospheric imbrication.