Machupuchare in the Annapurna Range of the Himalaya in central Nepal is a mountain influenced by monsoons.
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Courtesy of Kip Hodges

Storms Shaped the Himalayan Mountains
News story originally written on November 9, 2008

Rain is important for many reasons. It waters plants and allows animals to drink. It fills rivers and lakes. But did you know that it can affect mountains too?

Scientists have found evidence that strong storms shaped the Himalayan Mountains over millions of years.

The Himalayan Mountains are in Asia, where winds blow that carry moist air. These moist winds make monsoons, big storms that have lots of rain. There’s evidence that the monsoons have happened for at least 24 million years. But the storms have not always been the same.  Sometimes monsoons were very big and other times they were smaller storms.

To figure out how the monsoons have changed high in the Himalayas, scientists looked to the bottom of the ocean. They studied layers of sediments from the seafloor. The sediments were weathered from mountains, then moved in rivers before settling down on the seafloor.

The seafloor sediments shows how much of the mountain rock weathered away over time. The scientists found that more monsoons cause more weathering of rocks.

The scientists concluded that the Asian monsoons became stronger from 23 to 10 million years ago, and then became weaker until about 4 million years ago. After that, monsoons became stronger again.

Last modified December 2, 2008 by Lisa Gardiner.

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