"Mystery of the Himalayas solved"

The mystery of why the Himalaya mountains and the Tibetan plateau are the highest in the world has at last been answered, with the discovery of a gigantic chunk of rock slowly sinking towards the centre of the Earth.

When the massive slab - up to eight times the area of the UK and as thick as a dozen Everests on top of each other - dropped off, the lighter crust above it rebounded upwards like a cork released under water, geophysicists say. This "sudden uplift" would have raised the Himalayas by as much as 2km (1.24 miles) to their present height....

The discovery of the missing mantle - the cold, heavy rock beneath the crust - was revealed last week by Professor Wang-Ping Chen at the University of Illinois, whose team used more than 200 super-sensitive seismometers strung across the Himalayas, from India deep into Tibet.

"While attached, this immense piece of mantle under Tibet acted as an anchor, holding the land above in place," said Professor Chen, whose results are to be published in the Journal of Geophysical Research. "Then, about 15 million years ago, the chain broke and the land rose."

By pushing the Himalayas to their current altitude, more than 8,000m above sea level, and raising the Tibetan plateau to 5,000m, the detachment of the block was responsible for both the monsoon rains that make south Asia so fertile and the Gobi desert in central Asia. Warm winds blowing from the Pacific Ocean cool as they rise over the mountains, releasing the moisture they contain as torrential rains, leaving almost no water to fall on the arid interior of the continent.