Chapter 7
The periglacial environment
1. Introduction
The term "periglacial" was introduced in 1909 by the Pole, Lozinski, to designate the
climatic conditions and geomorphic features of the areas peripheral to the Pleistocene icesheets. Subsequently, the term has been extended to cover the characteristic processes and
landforms of cold climates, regardless of their proximity to glaciers or glaciated areas.
There are vast zones such as eastern Siberia unconnected to the glacial areas where
periglacial activity predominates (Jahn, 1975). Due to the lack of precision in the
definition, the term periglacial has had very wide use. Thus, the word "geocryology,"
commonly used by the Russian researchers, has been introduced as an approximately
equivalent, alternative term (Washburn, 1979). This science is commonly defined as the
study of the terrestrial materials with temperatures below 0~ that is to say permanently or
seasonally frozen grounds (Washburn, 1979; French, 1996).
Periglacial environments are characterized by freeze-thaw cycles and the presence of
permafrost or permanently frozen ground. Either or both of them occur in the overall
periglacial domain. In this way, some of the periglacial landforms are not associated with
the presence of permafrost. The periglacial environment is distributed in polar zones and
in medium and low latitude alpine areas of many mountain ranges of planet Earth (Harris,
1988). At the present time, the periglacial domain covers close to one fifth of the global
land surface and an additional 20% of the area has undergone periglacial conditions during
the Pleistocene cold periods (French and Karte, 1988).
Many palaeoclimatologists recognize the importance of periglacial phenomena for
palaeoclimatic reconstructions and of permafrost for palaeoclimatic modelling (Isarin,
1997). Ecologists and environmental scientists have pointed out the vulnerability of
present-day periglacial regions due to their increased anthropogenic use and the
implications of expected climate change (Vandenberghe and Thorn, 2002).
Periglacial environments have a wide range of climatic conditions. The mean annual
temperature may be close to or far below the freezing point, and the range between the
maximum and minimum yearly temperatures is generally large. According to Peltier
(1950), the annual precipitation varies between 130 and 1400 mm and between 50 and
1250 mm following Wilson (1969). Tricart (1967) has established a climatic classification
based on the temperature, precipitation, wind conditions, and their seasonal distribution.
Three types of periglacial climates are distinguished:
(a) Dry climates with cold winters. These conditions are found in subpolar zones of the
northern hemisphere. These areas have very low temperatures in winter, very short
summers, low precipitation, and strong winds. This climate propagates the existence
of a perigelisol (permafrost). The morphogenetic system linked to this climate type is
The periglacial environment
1. Introduction
The term "periglacial" was introduced in 1909 by the Pole, Lozinski, to designate the
climatic conditions and geomorphic features of the areas peripheral to the Pleistocene icesheets. Subsequently, the term has been extended to cover the characteristic processes and
landforms of cold climates, regardless of their proximity to glaciers or glaciated areas.
There are vast zones such as eastern Siberia unconnected to the glacial areas where
periglacial activity predominates (Jahn, 1975). Due to the lack of precision in the
definition, the term periglacial has had very wide use. Thus, the word "geocryology,"
commonly used by the Russian researchers, has been introduced as an approximately
equivalent, alternative term (Washburn, 1979). This science is commonly defined as the
study of the terrestrial materials with temperatures below 0~ that is to say permanently or
seasonally frozen grounds (Washburn, 1979; French, 1996).
Periglacial environments are characterized by freeze-thaw cycles and the presence of
permafrost or permanently frozen ground. Either or both of them occur in the overall
periglacial domain. In this way, some of the periglacial landforms are not associated with
the presence of permafrost. The periglacial environment is distributed in polar zones and
in medium and low latitude alpine areas of many mountain ranges of planet Earth (Harris,
1988). At the present time, the periglacial domain covers close to one fifth of the global
land surface and an additional 20% of the area has undergone periglacial conditions during
the Pleistocene cold periods (French and Karte, 1988).
Many palaeoclimatologists recognize the importance of periglacial phenomena for
palaeoclimatic reconstructions and of permafrost for palaeoclimatic modelling (Isarin,
1997). Ecologists and environmental scientists have pointed out the vulnerability of
present-day periglacial regions due to their increased anthropogenic use and the
implications of expected climate change (Vandenberghe and Thorn, 2002).
Periglacial environments have a wide range of climatic conditions. The mean annual
temperature may be close to or far below the freezing point, and the range between the
maximum and minimum yearly temperatures is generally large. According to Peltier
(1950), the annual precipitation varies between 130 and 1400 mm and between 50 and
1250 mm following Wilson (1969). Tricart (1967) has established a climatic classification
based on the temperature, precipitation, wind conditions, and their seasonal distribution.
Three types of periglacial climates are distinguished:
(a) Dry climates with cold winters. These conditions are found in subpolar zones of the
northern hemisphere. These areas have very low temperatures in winter, very short
summers, low precipitation, and strong winds. This climate propagates the existence
of a perigelisol (permafrost). The morphogenetic system linked to this climate type is