The sands of the Namib Sand Sea have been there for at least a million years reports a paper published online this week in Nature Geoscience. This suggests that, despite large-scale climate changes in the region over the past million years, at no time was the area completely cleared of sand.
Pieter Vermeesch and colleagues used geochemical tracers to track the movement of sand across the 400-km sand sea. They also measured radioactive isotopes produced by cosmic rays, which allowed them to estimate the amount of time that the sand had been present in the region. They conclude that it takes a minimum of one million years for winds to blow sands across the sand sea, although the sand dunes may not have been active for the entire time span.