Regolith

Key sites

Ward Hill

Lounders Fea,   a glacially-disturbed sandstone blockfield with extensive deflation surfaces

 

Erected pebbles and cracked clasts associated with former ground ice

Periglacial landscapes

Defintion: any area with a tundra climate, such as mountainous areas in mid-latitudes, or where frost processes are active or permafrost occurs in some form.

Two generations of periglacial feature exist on Orkney:

  • features active today or earlier in the Holocene
  • features formed under intensely cold conditions during the Loch Lomond Stadial and the early phases of deglaciation

Active periglacial features are confined to the hill tops of Hoy and reflect a prevailing environment of high wind speeds, heavy but now short-lived snowfalls, high ground moisture levels, and frequent freeze thaw cycles in winter. The relict forms reflect, at least in part, more severe periglacial conditions when permafrost may have been widespread. The former presence of ground ice allowed heave processes to move much bigger blocks than is currently possible and enhanced frost weathering generated large volumes of scree and other angular rubble.