How mountains grow

It was this shifting of the Earth's mantle and crust that was responsible for the rise of the Andes Mountains in South America – the second largest mountain belt in the world. But researchers are now realizing that the formation of these gigantic mountains did not happen as slowly as they had once believed. Carmala Garzione and her colleagues reviewed in-depth studies of layers of rock, lava flow, and the continuous movements of the Earth's crust to determine that the Andes Mountains actually formed rather abruptly, in a couple million years rather than tens of millions of years.

After reviewing the facts, Garzione and her colleagues now suggest that there are times during the formation of mountains when they stay the same height for tens of millions of years, and then rapidly grow taller for about one to four million years. They also believe that the abrupt formation of the Andes Mountains was caused by dense rocks at the base of the Earth's crust falling further down into the mantle.

The Andes Mountains affect the climate of a lot of South America, so understanding exactly how they rose from the Earth can tell us a great deal about how the land looked in the past and might look in the future. These new conclusions that suggest the Andes rose abruptly from the ground will change the way scientists study the history of our planet. -American Association for the Advancement of Science