The dark unit on the right side of the image shows signs of erosion in some parts, as it is no longer a continuous layer anymore and appears to have been more extensive in the past. Between the dark, resistant mounds, depressions can be observed. These circular to elliptical depressions are known as scalloped depressions. With higher-resolution imagery, such as HiRISE data, the naming of these depressions becomes clear: the morphology of the edges resembles the shape of scallops (see HiRISE image). Scalloped depressions are very common in the mid-latitudes, where subsurface ice is present, and are interpreted as a type of periglacial feature. They likely form through the removal of ice-rich subsurface material, either by melting or by sublimation (direct phase change to gas), followed by the collapse of the overlying terrain. The resulting subsidence of the surface due to ice loss in the subsurface is called Thermokarst. Scalloped depressions are characterized by a steep, pole-facing scarp and a gentler, equator-facing slope. This asymmetry is thought to result from differences in solar heating: greater solar insolation on the equator-facing slopes leads to more sublimation of ice than on the pole-facing slopes. These depressions do not occur in isolation but rather merge into larger areas, providing a perfect example of how Mars’s surface is constantly changing.