Remains of pingos in Wales and the Isle of Man

Remains of pingos have already been reported from east central Wales. This paper records a further group from west central Wales and a probable group from the Isle of Man. When they are compared with contemporary pingos it is clear that they belong to the open system type, which, in contrast with the solitary pingo of the closed system type, tends to occur in clusters of mutually interfering forms and on melting to result in a complex pattern of ramparts. Much of the recently discovered group in central Wales shows this complexity and suggests later pingos developing on the sites of earlier ones as the injection centres migrated upslope. On more open sites simpler solitary pingos occur, including some elongated forms. The Isle of Man group consists of depressions without ramparts but their location and orientation suggest they represent pingo basins. It is argued that although the most convincing evidence for pingos consists of arcuate to annular ramparts enclosing basins, the ramparts may disappear through cultivation.