During the ice ages there was much more dust in the air over Antarctica than there is now, but its supply was sometimes rapidly curtailed.
David Sugden of the University of Edinburgh, UK, and his colleagues suggest that an 80,000-year record of the extent of the glaciers in Patagonia, the likely source of the dust, may explain the uneven pattern of dust deposition seen in Antarctic ice cores.
When the glaciers were extended, their sediment-rich discharge flowed out over extensive plains. Here, their dusty sediments would have been easily mobilized by the wind. When the glaciers retreated — as they did on occasion, even in an ice age — they discharged instead into lakes (pictured), where the sediments simply accumulated. Glacier fluctuations correlate well with the Antarctic dust record.