Weird tracks in the snow made by little pebbles. They rise up through the snow, move a few centimeters per hour, and usually end their journey by diving back beneath the snow's surface. The pebbles need the sun's heat to move them. Tracks can go uphill or downhill. One theory is that the capillary force of melt water pulls the pebbles along. These pictures were taken at the Colorado National Monument, 2007-03-04. The two video links will show you one-half hour of real time compressed into a few seconds.
This was taken one day earlier a few miles away from the above photos. Note that one doodle did a 360 degree track and dropped back into its starting hole. The other doodle did a 180 and then ventured away at a right angle.