Growing Mountain

Even the tallest mountains on Earth can be eroded by the elements, things like wind and running water. And over the course of millions of years, even mountains wear away eventually. A reader wrote in to ask, “Do mountains ever get taller?”

Consider the highest mountains in the world — the Himalayas. These mountains were born in the collision of a plate of land — known to us as India — with the rest of Asia. India is thought to have started out much farther south on the globe — near Antarctica. There’s strong evidence that it traveled northward across Earth’s surface at a rate of about 80 kilometers — that’s about 50 miles — every million years.

Forty million years ago, India crashed into Asia. It ground its way under that larger plate of land — and as it did it pushed up a range of mountains — the Himalayas. And India hasn’t stopped moving since. India has now pushed over thousand kilometers under Asia. In the process, the Himalayas are still being raised up by about a centimeter a year.

So mountains do get taller. In the case of the Himalayas, this growth is offset by about the same rate of erosion that’s wearing the mountains down.

What you have in your mind?