This photograph shows a trail of footprints across Antarctica. The person who made them is long gone.

Raised footprints take weeks to form. They are the product of a very specific environment. The snow has to be loose and dry, so that the foot can sink in and compress the snow until it’s hard. Since snowfall and rain can spoil the print, the weather has to be dry. And there has to be constant wind. As someone walks, their feet tamp down the snow until it’s extremely hard in comparison to the snow all around it.

As the wind sweeps across the area, it whisks away loose particles of snow. It takes considerably longer to whisk away the compressed snow of the footprints. Eventually, the wind wears down an entire plain, or side of a hill, except for the hardened tracks in the snow.

http://io9.com/raised-footprints-when-snow-steps-up-473092187