Flow-like Features in Promethei Terra (extra-detail mgnf)

The subimage (approx. 390 x 260 meters) shows in detail some of the ridges developed in the slope deposits. Numerous fissures cut through the surface, forming polygons 5 to 10 mt (5,5 to 11 yards) across.
Such well-preserved polygons indicate that the downhill flow had stopped before they formed. Polygonal features similar to these are common in terrestrial periglacial regions such as Antarctica, where ice is present at or near the surface. Antarctica's polygons formed by repeated expansion and contraction of the soil-ice mixture due to seasonal temperature oscillations.