Atacama Desert’s center dried out 20 million years earlier than previously thought — before the Andes formed

A view of a large brown sandy desert.

The Atacama Desert started forming about 20 million years earlier than scientists previously thought, long before the nearby Andes Mountains took shape, new research reveals.

Previously, the desert's hyperarid core was thought to have developed between 15 million and 20 million years ago, around the time the Andes were forming and cold ocean currents were establishing off the Chilean coast. But the new study suggests those ultradry conditions were present more than 40 million years ago, indicating that one of the world's oldest deserts is even more ancient than we thought.