Abstract Permanently frozen ground may be a distinct possibility in all latitudes on Mars. Mean shallow subsurface temperatures are below the freezing point of water. Given a supply of water, either meteoric or juvenile, minor topographic features will develop in permafrost areas. These features include patterned ground, or ridges and troughs arranged in polygonal patterns, and irregular mounds formed by frost heaving. Because of the probable absence of liquid water on the surface, any ice-saturated permafrost will have formed from water that has reached the surface zone from the interior during volcanism or outgassing. Sand wedges may develop in the permafrost because of the seasonal expansion and contraction of that zone with alternate penetrations of the heat and cold waves. With the growth of these wedges, patterned ground may develop on the surface. Any downward percolating water from the surface or hoar frost crystals forming in fractures could aid this process.