Click for original picture.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on February 19, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows an avalanche that slumped downward out of the material that forms the interior western wall of an unnamed 25-mile-wide crater about 100 miles east of Gale Crater, where Curiosity has been roving for more than a decade.

The scientists call these types of Martian avalanches “mass-wasting events”, since the entire mass of the cliff moves downhill in a chunk, rather than as a pile of rocks that grows in size and strength as it picks up material on its way down.

It is not clear how old this slide is. A lot of the material on this slope appears to be Martian dust, some of which has flowed into the avalanche material after it had slide downhill.

The white dot to the east of Gale Crater in the inset of the overview map to the right marks the location of this landslide. Notice how the terrain east of Gale appears to be similar to chaos terrain, with a slight suggestion that the downhill grade is to the east. In the mid-latitudes of Mars such chaos terrain is often filled with glacial features, with the shaping of this terrain possibly linked to the long-term motion of that ice.

Here in the dry equatorial regions however the evidence suggests there is no near surface ice. If this landslide occurred because of an underground layer of ice, that ice has long ago sublimated away. If so, the slide is very old. Moreover, the chaos terrain might be as old if not older, coming from a time when Mars’ equatorial regions were not dry.

It is also possible that the slide is young, and was caused simply because of the structurally weakness in the alluvial fill that makes up this slope. Much of the dust in this area likely came from the nearby Medusae Fossae Formation, the largest volcanic ash deposit on Mars, from which some scientists believe most of the dust on Mars originates.