This image, near the southeast rim of Peneus Patera crater, is marked by depressions in the mantle with scalloped edges. Several of the depressions have apparently coalesced together.
These features are most commonly found at approximately 55 degrees North and South latitude. Their presence has led to hypotheses of the removal of subsurface material, possibly interstitial ice by sublimation (evaporation).
Steep scarps consistently face the south pole while more gentle slopes face in the direction of the equator. This is most likely due to differences in solar heating.
A polygonal pattern of fractures, commonly associated with "scalloped terrain," can be found on the surface surrounding and within the depressions. The fractures indicate that the surface has undergone stress that may have been caused by subsidence, desiccation, or thermal contraction.
Scallop formation is believed to be an ongoing process at the present time.
Photo credit: NASA/JPL/University of Arizona
Note: Peneus Patera Crater is located just south of Hellas Planitia in the Noachis Quadrangle of Mars.
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