The Himalayan mountain range stretches from Brahmaputra to the Indus River. It ranges over 2500 km and about 250 km thick. So how were these Great Himalayas built?
During the late Neoprotozoic era (1000mya-541mya) and early Palaeozoic (541-252mya) , the Indian tectonic plate was a part of the southern Gondwana land .This was separated by the Eurasian plate by the large Tethys ocean . In the early Carboniferous period , an early stage of rifting developed between the Indian subcontinent and the Gondwana land.
What is a Rift?
A rift is a zone where the lithosphere layer is stretched or pulled apart. In the early stage ,the upper part of the lithosphere starts to extend . As it evolves,some of the fault zones start to connect with each other and become even larger bounding faults .The crust becomes thin causing the rise of Asthenosphere. This way two new tectonic plates are formed from the older single one.
In the Norian period(210 mya), after a major drifting episode the Gondwana land split into two parts. The Indian subcontinent became a part of East Gondwana along with Australia and Antarctica. Later in the early Cretaceous(130 -125 mya), the Indian plate broke off from Australia and Antarctica with the ‘formation’ of Southern Indian Ocean.
At the end of Cretaceous period ,the Indian plate started drifting northward at speeds of about 18 to 20 cm per year which is the highest among all the continental drifts. It covered a distance of more than 6000 km in that time and rotated about 45° counterclockwise relative to the Eurasian plate. Interaction of the Eurasian plate with the coming Indian plate started at about 65 million years ago with the oceanic crust of the latter subducting under the Eurasian plate.
This started the formation of the youngest mountain ranges of the world , The Great Himalayas . This collision was so strong that till present also the Indian plate is colliding northward and the Himalayas continue to rise more than 5 mm a year but due to the stretching of Eurasian plate horizontally and effect of gravity this rising is affected.￼
Effect on Climate
According to a report of ‘Nature’ magazine, the Himalayan range ormation may have also started Asia’s monsoon about 8 million years ago and contributed to several ice ages that began 2.5 million years ago. The mountain’s and Tibetan Plateau’s uplift gave rise to a dry Central Asia that resulted in the formation of Gobi and Mongolian deserts.
This may have caused a dustier phase in the earth’s atmosphere . The Himalayan range obstructs the passage of cold continental air from north into India in winter and also forces the south westerly monsoon winds to give up most of their moisture before crossing the range northward.
The Himalayas are gigantic and lively and on the other hand they are calm and tranquil, perfect for the soul to grow spiritually.