South Polar Fans (Natural Colors; credits: Lunar Explorer Italia)

Caption NASA:"Every Winter, Mars' Polar Region is covered with a layer of seasonal CO2 (Carbon Dioxide ice - a.k.a. "dry ice"). In the Spring, jets of gas carry dust from the ground up through openings in the ice.
The dust gets carried downwind by the prevailing wind and falls on top of the Seasonal Ice Layer in a fan-shaped deposit. Many jets appear to be active at the same time since numerous Fans are all deposited in the same direction.

This image from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter appears to show several times at which jets were active. At the top of this image the Fans are oriented in one direction while at the bottom they are going in a different direction. This suggests that as the ice layer thins, a set of gas jets becomes active, they die down, then further away another set starts up at a later time with a different prevailing wind direction.
This is a reduced-resolution image from the HiRISE Observation observation catalogued as ESP_011934_0945, taken on Feb. 11, 2009. The observation is centered at 85,4° South Latitude and 104,0° East Longitude.

The image was taken at a Local Mars Time of 18:12 and the scene is illuminated from the West, with a Solar Incidence Angle of 79° (meaning that the Sun was about 11° above the Local Horizon).
At a Solar Longitude of 207,9°, the season on Mars is Northern Autumn".