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Let’s begin with the first physiographic division. It consists of:
The name “Himalaya” means “the abode or house of snow” in Sanskrit (i.e. hima “snow”, and ālaya “abode or house”). The Himalayas are the highest and longest of all young fold mountains of the world. The Pamir, known as the roof of the world, connects the Himalayas with the high ranges of Central Asia.
Let’s begin by understanding how the Himalayas came into being:
According to the theory of Continental Drift, the world was made up of a single continent through most of the geologic time. That continent eventually separated and drifted apart; forming the seven continents we have today.
About 200 million years ago: Pangaea broke apart leading to the formation of two landmasses – “Laurasia in North” and “Gondwanaland in South”. Both the landmasses were separated by a shallow sea called “Tethys Sea”. The size of Tethys sea kept on decreasing due to movement of landmasses towards each other
About 40 to 50 million years ago: The two large landmasses, India and Eurasia, driven by plate movement, collided. As a result, the sediments accumulated in Tethys Sea (brought by rivers) were compressed, squeezed and series of folds were formed, one behind the other, giving birth to folded mountains of the Himalayas.
Recent studies show that India is still moving northwards at the rate of 5cm/year and crashing into the rest of Asia, thereby constantly increasing the height of Himalayas.
1. Fossil formation found in Shivalik hills:
Similar fossils have also been found in the Tibet Plateau. This indicates that in the past, Tibetan plateau and Shivalik hills shared a common location, similar level and thus similar vegetation, life etc.; then Tibetan plateau got uplifted.
2. Desiccation of lakes of Tibet:
In the Tibet plateau, we find deposits which are generally found in lakes. This indicates that lakes once existed in Tibet but because of upliftment the water got discharged and deposits remained.
3. Frequent Earthquakes
4. Youthful nature of rivers (High erosion, v-shaped valleys etc.)
The Himalayas consist of a series of parallel mountain ranges:
Indus-Tsangpo Suture Zone: It represents a belt of tectonic compression caused by the underthrusting of the Indian shield/ plate against the Tibetan mass. It marks the boundary between Indian and Eurasian plates. The suture zone stretches from the North Western Himalayan syntaxis bordering the Nanga Parbat to the East as far as the Namche Barwa Mountain. Tha Karakoram range and the Ladakh plateau lie to the north of ITSZ and originally formed a part of the European plate.Main Central Thrust Zone: This separates the Higher Himalayas in the north from lesser Himalayas in the south. It has played an important role in the tectonic history of these mountains.Main Boundary Thrust: It is a reverse fault of great dimensions which extends all the way from Assam to Punjab and serves to separate the outer Himalayas from the lesser Himalayas.Himalayan Frontal Fault: It is a series of reverse faults that demarcates the boundary of the Shivalik from of the Himalayan province from the alluvial expanse of the Indo-Gangetic plains.
That’s it for this part! In the next article, we will East-West division of Himalayas. (Click here for the next part)