English: NASA wrote the following caption for this image: HiRISE images often raise more questions than answers. For example, this image of the northern plains of Arabia Terra shows craters that contain curious deposits with mysterious shapes and distribution.

The deposits are found only in craters larger than 600 meters in diameter and are absent from craters measuring 450 meters and less. The deposits are located on the south sides of the craters but not in the north (although the cutout shows a crater that also has windblown deposits in the north). The deposits have horizontal laminations that could be layers or terraces. The deposits also have radial striations formed by small bright ridges.

We suspect that these features formed by sublimation of ice-rich material. The terraces might represent different epochs of sublimation. Perhaps the larger craters penetrated to a water table between 45 and 60 meters below the surface and were flooded after formation.

Written by: Paul Geissler (14 December 2022)