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PERIGLACIAL LANDSCAPES 279














































                     Sub-sea                                                         Alpine
                     permafrost                                                  permafrost
                     Continuous                                               Discontinuous
                     permafrost                                                  permafrost

              Figure 11.1 Distribution of permafrost in the Northern Hemisphere. Isolated areas of alpine permafrost, which are not
              shown, are found in high mountains of Mexico, Hawaii, Japan, and Europe.
              Source: Adapted from Péwé (1991)


              landform initiation and evolution (Thorn 1992). It  onfloodplains;ice from sublimation,whichisformedin
              comes in a variety of forms (Table 11.1): soil ice (needle  cavities by crystallization from water vapour; and buried
              ice, segregated ice, and ice filling pore spaces); vein ice  ice (buried icebergs and buried glacier ice) (Embleton
              (single veins and ice wedges); intrusive ice (pingo ice and  and King 1975b, 34). Some ground ice lasts for a day,
              sheet ice); extrusive ice, which is formed subaerially, as  forming under present climatic conditions, some of it
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