polygonal ground

Polygonal ground, also known as tundra polygons, is a widespread geomorphic feature associated with permafrost. It appears as a network of shallow troughs that form polygons, typically 3 to 30 meters in diameter. These troughs are underlain by ice wedges, which are vertical ice formations that join together in a honeycomb pattern.1

The formation of polygonal ground is driven by the freeze-thaw cycle in permafrost regions. As water in the soil freezes, it expands, creating cracks. In the spring, meltwater fills these cracks, freezes, and expands further, forming ice wedges. This repeated process deforms the surrounding soil and can create raised ridges around the polygons, known as low-centre or high-centre polygons. These features are excellent indicators of permafrost and can even be found as relicts in areas that were once periglacial.12