Snow Rollers

This is too cool. "Snow rollers form when the snow has just the right combination of sticky snow that is light enough to be moved by wind. If the wind is strong enough, it picks up snow crystals and begins to tumble them over across 'downstream' snow cover. Soon a little mini snowball forms. As it grows and increases surface area, the wind gusts push sheets of snow along." There are some more photos of snow rollers over at Flickr.