ESA’s Mars Express orbiter shot these photos in June, which would have been winter in the southern hemisphere. The terrain here is very old, which you can tell by the filled-in craters. The area also has smaller pedestal craters, where the ejected material forms a plateau in the surrounding area. ESA explains: “The ejecta surrounding pedestal craters form erosion-resistant layers, meaning that the immediate vicinity around the crater erodes more slowly than the surrounding terrain. The resistant ejecta layer is largely untouched, forming the pedestal.” These stand out in three dimensions thanks to the Mars Express stereo camera. Look at the image above for some further detail. This large crater shows some interesting sedimentary deposits, which appear to have entered the crater through a breach in its northern rim. Several of the other annotated boxes also depict dunes and sedimentary deposits. Planetary geologists are studying these features to determine how they form. As the Mars rover Curiosity and its predecessors have shown, Mars once had plenty of water flowing across its surface, which is a likely culprit in forming these deposits. ESA
