Another dune-like feature, which is known as Transverse Aeolian Ridges (TARs) can be found in Moni Crater, located within Kaiser Crater. These exhibit characteristics of both ripples and dunes (also see HiRISE image). With up to 14 meters of height they are significantly larger than ripples but smaller than dunes. They were probably formed by martian winds and might be made up of fine grained bright sand.

 In some places near the dune field, wind erosion has eroded the soil, exposing the underlying layers. These appear as light-coloured deposits (see annotated image) and suggest the presence of clay minerals, which typically form through the weathering of basalt – the volcanic parent rock – in the presence of water.

 If you look closely, you can also see the wind in action here: a small light-coloured spot with a red fringe is a dust devil currently moving across the Martian surface. The long shadow cast by this dust devil reveals that it reaches a height of approximately 1.9 kilometres (calculated from the shadow’s length and the position of the Sun). Dust devils are a widespread phenomenon on Mars and have often been observed in HRSC images (see 2026 press release of Mamers Valles).

 Another intriguing geological feature, also attributed to water activity, can be found within some of the smaller craters, such as the small impact crater located inside Kaiser Crater itself. Gullies are clearly visible along its steep inner crater walls, forming narrow channels that run downslope (see annotated image). These gullies may have formed when water from melted ice or from groundwater reservoirs triggered debris flows, transporting material down the crater wall.