What Holds Up the Himalayas?

Scientists have discovered that a 100-year-old theory about Earth’s highest mountain range is wrong.

The Himalayas were formed when the Asian and Indian continents collided around 50 million years ago. Tibet was squeezed so hard it crumpled and shrank. Eventually, India slipped under the Eurasian tectonic plate, which doubled the thickness of Earth’s crust beneath the Himalayas and Tibet.

Until now, the theory has been that this extra-thick crust carries the weight of the Tibetan Plateau and the Himalayas. In 1924, geologist Emile Argand published research showing the 2 crusts stacked on top of each other, stretching 45-50 miles (70-80 km) deep under Earth’s surface.

But researchers now say that rocks in the crust turn molten about 25 miles (40 km) down because of extreme temperatures. The lowermost layers become like yogurt, which won’t support a mountain.

New research says there is a piece of mantle sandwiched between the 2 crusts. The mantle is a layer that usually sits directly beneath the crust. Being denser than the crust, it doesn’t liquify at the same temperatures. The crust is buoyant, similar to an iceberg. It lifts higher the thicker it gets.

A computer simulation of the collision between the Asian and Indian continents showed that as the Indian crust began to liquify, blobs of it rose and attached to the base of the rigid outer layer. This means there is a rigid layer of mantle between the stacked crusts, which solidifies the structure beneath the Himalayas. While the 2 crusts give buoyancy to the region lifted, the mantle material provides mechanical strength.

Then the researchers compared their simulation with seismic data and information obtained from rocks. They found that the mantle sandwich matched previous evidence that Arnand’s theory couldn’t explain. Enigmatic observations are more easily explained with this model. This study presents strong evidence, but it is controversial because Arnaud’s theory has been widely adopted.

These results explain a number of geological oddities in the region. The scientists ran lots of simulations using different thicknesses for the layers, and they always got a bit of mantle sandwiched between the 2 crusts.

 

https://www.msn.com/en-us/news/world/the-geology-that-holds-up-the-himalayas-is-not-what-we-thought-scientists-discover/ar-AA1Ly8l6?ocid=hpmsn&cvid=58b796c6ff6143d886f6d7199af0640e&ei=51