In the so-called dry valleys of Antarctica, and indeed in other cold arid regions, a variant of ice wedge polygons is often observed. Instead of the wedges forming the periphery of the polygons being gradually filled with ice, they are for the sand wedge polygons gradually filled with wind blown sand. For this reason they are even closer in form and origin to the detritus wedge polygons forming as alligator cracks in asphalt pavements.
I mention these in passing in order that the extremely close analogies in the genesis of all these processes might be appreciated.
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