Scalloped Depressions with Layers

This image, of the northern plains of Mars, is marked by depressions in a layer of material that covers the region. The depressions, several of which have coalesced together, have scalloped edges and layers in their walls.Their presence has led to hypotheses of the removal of subsurface material, possibly ground ice, by sublimation (evaporation). This process is believed to be ongoing today.

https://uahirise.org/hipod/PSP_002439_2265
NASA/JPL-Caltech/University of Arizona