Pingo Mapping Project

In simple terms, pingos were conical, ice-cored mounds which formed in permafrost regions as a result of frozen ground being forced upwards by the growth of a large ice mass as water under pressure froze below the surface. Disturbance of the vegetation and soil as the pingo increased in size caused exposure of the underlying core of ice.  When the ice melted, the pingo collapsed, leaving behind a central depression or crater, with a rampart of displaced sediment around the rim.

The remnants of collapsed pingos, and other ground-ice depressions which formed in periglacial conditions (eg thermokarst hollows), are typically found in East Anglia in the eastern margins of the Fens and the Breckland valleys, and are characteristic features at SSSIs such as Thompson Common, East Walton Common and Foulden Common. These landforms occurred in clusters, sometimes at a density of one hundred per square km, although the average density may be less than half this number.  Many relict pingos and related ground-ice depressions have an associated fen habitat, but a great many sites have been cultivated or destroyed, and a large number have become overgrown and are now located in woodland.

This project has identified and mapped for the first time the distribution of these sites across Norfolk, helping to ensure that they are properly recognised, protected and managed to conserve both their geological and floristic value. During the project, condition assessments were also carried out over 70 sites to identify those at risk from potentially damaging activities, or from natural processes such as scrub encroachment and succession.

Download the Pingo Report 2007-2008
Download a PDF Map showing the distribution of pingo sites in Norfolk