Parts of the surface show flow patterns that start in numerous alcoves located within the walls of plateaus.

[4] It is strongly believed that beneath a thin layer of rock and dust lie vast reservoirs of ice.

[11] Furthermore, at this high tilt, stores of solid carbon dioxide (dry ice) sublimate, thereby increasing the atmospheric pressure.

[14] When the tilt begins to return to lower values, the ice sublimates (turns directly to a gas) and leaves behind a lag of dust.

[15][16] The lag deposit caps the underlying material so with each cycle of high tilt levels, some ice-rich mantle remains behind.

[17] Note, that the smooth surface mantle layer probably represents only relative recent material.