Geography Reference
In-Depth Information
FIGURE 1.1
Mountains of the world (UNEP World Conservation Monitoring Centre 2002: 12-13). The
boundaries and names shown and the designations used on maps do not imply official endorse-
ment or acceptance by the United Nations Environment Programme or contributory organiza-
tions.
Accordingly, a geoecological approach has been suggested for determining the lower
limit of high mountain environments. There are three main criteria: High mountains
should rise above the Pleistocene snow line, the zone of rugged and serrated topo-
graphy associated with mountain glaciers and frost action; high mountains should ex-
tend above the regional (natural) timberline; and high mountains should display cryo-
nival (i.e., cold climate) processes such as frost-heaving and solifluction (Troll 1972,
1973). Although each of these may exist at various altitudes, and one may be more im-
portant in some areas than in others, when considered together they provide a fairly
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