Atacama desert dating
This is done with a technique that measures the changes in sediment grains caused by exposure to cosmic rays, high-energy particles bombarding Earth from space.
"We found loose sediment surfaces that would be washed away by any desert rainfall and these are older than 20 million years," he said.
The lower image, which includes both visible and infrared light, helps distinguish between snow and clouds.
Snow is dark red, while clouds are lighter shades of orange and white. Parts of the Atacama Desert receive just 1 to 3 millimeters of precipitation per year (the local average is 50 mm, or 2 inches). Along with the snowfall, the winter storm also brought temperatures of -8.5C (17.6F) to Santiago, Chile.
"The origin of the aridity in the Atacama dates back to the opening of ocean pathways - the opening between South America and Antarctica, and between Australia and the Antarctic.Parts of Uruguay and Argentina also coped with freezing temperatures.Several major copper mines were shuttered and overland transportation was snarled due to the snow, heavy rains, and flooding, according to news reports.It may also explain why earthquakes in the region can be so large."Interlocking shear stresses build up so much and if they are released, they produce much stronger earthquakes than are seen in other areas," Dr Dunai explained.