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Cool image time! The photograph to the left, cropped to post here, was part of the November image dump from the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a wind-swept dusty plain trending downhill to the west that is filled with more than a hundred depressions or sinkholes.

Unlike other pit images I have posted previously, this one is not focused on one particular pit or a string of pits. Instead, what makes it interesting is the large number of pits, scattered across the terrain in a random pattern. Their random distribution suggests that they are unrelated to any specific underground feature, such as a lava tube. Instead, some aspect of the underground geology here is causing the ground to sink at random points.

Below is an overview map showing where this dusty pit-strewn plain is located, indicated by the blue cross.

South of the solar system’s largest volcano, Olympus Mons, this region is part of of the transition zone between the Tharsis Bulge where Mars’ giant volcanoes are located, down to northern lowland plains, shown in blue to the west.

I do not know whether these pits formed from volcanic activity or some underground erosion process. At a latitude of only 9 degrees north the presence of abundant underground water is unlikely, though not impossible. Yet, the pits might be very old, formed at a time when Mars’ climate was wetter and the transition zone was a region where liquid water might have intermittently ebbed and flowed across the terrain.

All speculation. I just like the weirdness of this pitted plain.