This looks like an example of the polygonal terrain known on Mars since the time of the Viking missions. It has been likened to similar terrain seen in periglacial regions on Earth.
Perhaps Nick can answer a question for me. On Earth such polygons only last on the order of thousands of years and require liquid water for their formation. Then why was this not taken on Mars as an indication of near surface liquid water within that time frame? Perhaps on Mars it is hypothesized that there are less active erosional factors and climate changes that would serve to erode the polygons?

BTW, found this interesting web page on subsurface ice in the dry valleys of Antarctica that mentions speculation that this ice may be on the order of 8 million years old. Then perhaps the polygons seen in this region are also that old?

Buried ice could hold ancient secretshttp://www.usatoday.com/weather/antarc/sun/2001-01-07-old-ice.htm

Bob Clark