A study is defying a 100-year-old belief about what keeps the world’s highest mountain range aloft. The Himalayas have been standing tall in Asia ever since they were formed 50 million years ago. As the Asian and Indian continents collided, tectonic forces squeezed Tibet, reducing the area by almost 1,000 kilometres. The Indian tectonic plate slipped under the Eurasian plate, acting as a platform for the Himalayas and Tibetan Plateau to the north as the thickness of Earth’s crust doubled. This was first confirmed by Swiss geologist Émile Argand in 1924, who said that the Indian and Asian crusts are stacked on top of each other and stretch for 70 to 80 km deep beneath Earth’s surface. But a new study states that this is not possible.
According to a paper, the rocks in the crust turn molten around 40 km deep due to extreme temperatures. Pietro Sternai, an associate professor of geophysics at the University of Milano-Bicocca in Italy and the lead author of the study, told Live Science, “If you’ve got 70 km of crust, then the lowermost part becomes ductile… it becomes like yogurt — and you can’t build a mountain on top of yogurt.” Sternai says that their analysis reveals that there is a third layer, a piece of mantle, sandwiched between the Asian and Indian crusts. This led the Himalayas to not only grow tall, but has also helped them stay high. The paper was published on August 26 in the journal Tectonics. Also Read: Pieces of lost continent found under Antarctica and India point to one thing
Blobs are holding Himalayas aloft
This layer sits directly beneath the crust, and its high density ensures that it doesn’t liquify at high temperatures. It is light and buoyant, and lifts up higher above Earth’s surface like an iceberg. The team of scientists created a simulation of the collision between the Asian and Indian continents. They noted that as the Indian plate slipped beneath the Eurasian plate, blobs rose up and attached themselves to the bottom of the Asian crust and the base of the lithosphere. Sternai say that this shows that a rigid layer is present between the two plates. He says that this creates the perfect conditions for the Himalayas to stand tall. “You’ve got all the ingredients you need to uplift topography and sustain the weight of the Himalayas and Tibetan plateau,” he said.
Meanwhile, the authors are aware that defying Argand’s theory isn’t easy and borders on controversial. But they are aware that the study results should not be ignored since they explain several geological oddities in the Himalayas.