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Among the collection of articles in this section, find more on the intriguing genesis and growth of the Himalayas, and the geography of the region.
Origin: The highest and youngest mountain range in the world, the Himalayas are a geologic marvel that occurred when the Indo-Australian plate collided into the underbelly of the Eurasian plate, about 70 million years ago. The Tethys Sea that had existed in the location, disappeared, and as the Indian landmass continued to ram into Asia, the soft sediments that had lain at the bottom of the Tethys Sea were pushed up in a series of gigantic folds of the Earth's lithosphere, to reach a height of 8850m straight from sea level. Since the Indo-Australian plate is still moving-at 67 mm per year-the Himalayas are still rising, making the area geologically unstable and seismically active. It is predicted that in the next 10 million years, the Indo-Australian plate will move 1,500 kilometres forward into Asia.

Geography: Stretching in an immense arc of 2500 kms in length with a width ranging from 240 to 330 kms, along the boundaries and covering parts of 5 Asian countries, the Himalayas span an area of 750,000 sq. kms.. The Himalaya range sits amidst multiple overlapping ranges that make up the mountain complex of Asia: the Himalaya, the Hindu Kush, Karakorums, Pamirs, Tien Shan and Kun Lun, and forms a geographical divide between the Indian subcontinent and Central Asia. The Himalaya system itself comprises three parallel, longitudinal belts, running east to west:
  • the Outer Himalayas (Shivaliks), the youngest and just a couple of thousand feet in height, at the southern end,
  • the Lesser Himalayas, lying north of the Shivaliks and rising steeply to 20,000 feet,
  • the Greater and Trans Himalayas, a chain of mighty peaks at the northern end.
The lesser ranges jut southward from the main body at both the eastern and the western ends, and the Tibetan plateau lies north of mountain system. From east to west, the Himalayas may be divided into three regions: western Himalayas, central Himalayas, and eastern Himalayas, from the Brahmaputra-Tsangpo gorge below Namche Barwa in the east to the Indus trench below Nanga Parbat in the west. The countries that form part of this mountain system include: India (Assam Himalaya, Central Himalaya, Kashmir Himalaya and the Trans-Himalayan region of Ladakh), Nepal, Bhutan, China (Tibet), and a small part of Pakistan. Areas that are also included in the Himalayan region are the 'Terai', the upper section of the Gangetic Plains and the 'Bhabar', the area abutting the Siwaliks.

The geology of the Himalayas is a result of its birth process. The continental collision led to a complex structure of deformations of the lithosphere. Multiple litho-tectonic zones/units with distinct rock sequences formed as a result: the Trans-Himalaya, Tethyan Himalaya, Higher Himalaya, Lesser Himalaya and the Sub-Himalaya, bounded by the fault/thrust zones of the Indus-Tsangpo suture zone, South Tibetan Detachment, the Main Central Thrust, Main Boundary Thrust and the Himalayan Frontal Thrust. The base of the Tethys Trench that was compressed and folded in the process of mountain building, consisted of weak sedimentary rocks that were pierced by the granite and basalt of the Earth's underlying mantle.

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