Scientists have solved the mystery of why the world's highest mountains sit near the equator - colder climates are better at eroding peaks than had previously been realised.
Mountains are built by the collisions between continental plates that force land upwards. The fastest mountain growth is around 10mm a year in places such as New Zealand and parts of the Himalayas, but more commonly peaks grow at around 2-3mm per year.
In a study published today in Nature, David Egholm of Aarhus University in Denmark showed that mountain height depends more on ice and glacier coverage than tectonic forces. ... At cold locations far from the equator, he found, erosion by snow and ice easily matched any growth due to the Earth's plates crunching together.
At low latitudes, the atmosphere is warm and the snowline is high. "Around the equator, the snowline is about 5,500m at its highest so mountains get up to 7,000m," said Egholm. "There are a few exceptions [that are higher], such as Everest, but extremely few. When you then go to Canada or Chile, the snowline altitude is around 1,000m, so the mountains are around 2.5km." ...
Thursday, August 13, 2009
I'm always interested in new "facts" that explain the world to me. I just ran across this article by Alok Jha in the Guardian: