Geology Reference
In-Depth Information
Figure 1.1.
Schematic diagram illustrating limits of the periglacial zone: (A) high latitudes;
(B) alpine areas.
milieu is that where the infl uence of freeze-thaw oscillations is dominant” (Tricart, 1968,
p. 830). Second, there is the presence of perennially-frozen ground, or permafrost. Accord-
ing to T. L. Péwé, “permafrost is the common denominator of the periglacial environment,
and is practically ubiquitous in the active periglacial zone” (Péwé, 1969, p. 4).
Periglacial geomorphology developed rapidly in the 1950-1970 period as a sub-
discipline of a European-dominated climatic geomorphology (Büdel, 1963, 1977; Tricart,
1950, 1963; Tricart and Cailleux, 1967). During this period, the International Geographi-
cal Union (IGU) supported a Periglacial Commission under the leadership of Professor
J. Dylik between 1952 and 1972. An international journal,
Biuletyn Peryglacjalny
, was
started in Łód´, Poland, in 1954.
In hindsight, there were several weaknesses associated with the growth of periglacial
geomorphology. First, there was a largely uncritical acceptance of mechanical (frost)
weathering and of rapid cold-climate landscape modifi cation. Second, the variability,
duration, and severity of cold-climate conditions, both today and during the Quater-
nary, were not fully appreciated. Another concern was that insuffi cient consideration
was given to the infl uence of lithology in controlling landforms. A fi nal concern related
to terminology. Although “cryo” terminology had been proposed earlier to refl ect the
cold-climate (cryogenic) processes involved (Bryan, 1946, 1949; Capello, 1959), the
Pleistocene orientation of periglacial geomorphology led to acceptance of the term
