Polygonal patterned ground

Polygonal, patterned ground is quite common in some regions of Mars. It is commonly believed to be caused by the sublimation of ice from the ground. <a href="/facts/Sublimation_(phase_transition)/KDoKokMn">Sublimation</a> is the direct change of solid ice to a gas. This is similar to what happens to <a href="/facts/Dry_ice/BvW99HtH">dry ice</a> on the Earth. Places on Mars that display polygonal ground may indicate where future colonists can find water ice. Low center polygons have been proposed as a marker for ground ice. Polygonal terrain is also found on earth's <a href="/facts/Permafrost/SkFC7LMT">permafrost</a>.
Patterned ground forms in a mantle layer, called <a href="/facts/Latitude_dependent_mantle/sjSUP0k5">latitude dependent mantle</a>, that fell from the sky when the climate was different.
On Mars, researches have found patterned ground that formed from fractures and patterned ground formed by the arrangement of boulders. It is not yet clear what caused boulders to form patterns, but it does not seem that fractures caused the boulders to move around.

Polygonal patterned ground open-in-new

Polygonal patterned ground