This image, and the associated subimage, show changing dunes and incised gullies in the southern Matara Crater.
Repeat imaging of the dunes in this crater shows that material towards the top of the gullies has moved downslope (towards the left in subimage), and the channel beds may have widened over time. Because this activity occurs during Martian Southern hemisphere winter, it is believed to be related to carbon dioxide frost that forms as the area grows colder. Scientists continue to monitor this region for changes in the gullies and the dunes themselves.
Written by: Kristin Block (9 February 2011)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_020058_1300
Image: NASA/JPL/University of Arizona