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Today’s cool image to the right, rotated and cropped to post here, shows a gully flowing down the north facing rim of a 30-mile-wide crater in the southern cratered highlands. It was taken on June 30, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
To my eye the corroded ridges and pits running down the western side of this gully look like a corroded ice, as if we are looking at a glacier that the light of the Sun, which in the southern hemisphere hits this north-facing slope more directly and for longer periods of time, is causing it to sublimate away with time.
The wider shot below shows the entire rim, flowing downhill from the south to the north.
The material above the rim also appears to be glacial, at least superficially, in that the canyon floors all appear to be filled with buried ice, with a general flow downhill towards this particular gully.
All this is a pure guess on my part as a amateur planetary scientist, and should not be taken very seriously. The latitude however, 43 degrees south, lends weight to my suppositions.
Regardless, the gully suggests the potential for seasonal changes from year to year. Unfortunately, scientists have not done this, likely because there are far too many similar good targets on Mars. This image is the first high resolution image taken of this gully by MRO.
The crater itself is located on the western edge of Icaria Planum, a relatively flat plain about 350 miles wide in the southern cratered highlands and located about 1,200 miles south of Arsia Mons and Valles Marineris.
The overview map to the right gives the context. The tiny white box on the western edge of Icaria Planum indicates this crater’s location.
This location is also at the southern edge of the Tharsis Bulge, where all of Mars’ biggest volcanoes are located. Thus, what we see here could also be volcanic in nature, or at least shaped initially by lava flows and impact, then overlain by glacial material and windblown sand and dust later.