The secret ingredient holding up the world's highest mountains

Nature · Published 22 October 2026 Swipe more like this →

In short: For a century, geologists believed the Himalayas were supported by two stacked layers of Earth's crust. But new research suggests that if this were true, the mountains would literally sink into molten rock. The real secret lies in a hidden sandwich of dense mantle material.

The formation of the Himalayas began approximately 200 million years ago as the supercontinent Pangea started to fracture. The Indian tectonic plate broke free and migrated northward toward Asia at speeds exceeding 30 feet per century. During this journey, it crossed the Tethys Ocean; as the plates collided roughly 50 to 60 million years ago, the oceanic crust subducted, scraping seafloor sediments into a pile that would eventually be squeezed into the mountain peaks we see today.

The collision was so violent that it crumpled the landscape over 1,500 miles and caused Tibet to shrink by nearly 620 miles (1,000 kilometers). During many years, researchers used a 1924 concept from Émile Argand suggesting that Asian and Indian crustal layers piled vertically for 45 to 50 miles. However, this model faces a physical impossibility: at depths of about 25 miles (40 km), extreme temperatures turn crustal rock into a ductile state similar to yogurt.

A study published in the journal Tectonics on August 26 reveals that the mountains are actually supported by a piece of mantle sandwiched between the two continental crusts. Because the mantle is significantly denser than the crust, it does not liquefy at those temperatures. This 'sandwich' structure explains how the Himalayas maintain their immense height despite the weight they carry. Today, these tectonic forces continue to shape Asia, with Himalayan erosion even playing a role in keeping Bangladesh above water by feeding the Ganges-Brahmaputra delta.

The documentary Voyage of the continents highlights that Asia is still being built through these ongoing processes. From volcanic scars to river sediments, the continent serves as a living laboratory for how continental collisions raise ocean floors into some of the tallest peaks on Earth.

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