Criteria to discriminate between proglacial and paraglacial environments

the original meaning of “areas peripheral to Pleistocene ice sheets and glaciers” (Lozinski 1909) to one which stresses the distinctive processes of freeze-thaw and permafrost formation. In spite of the comment by Worsley (2004) that the term periglacial has no universally accepted definition, there are really only two options that are in common use: a) an environment of frequent freeze-thaw cycles and deep seasonal freezing (encompassing about 35% of the earth’s continental surface and/or b) a permafrost environment (only 20%). The international journal Permafrost and Periglacial Processes implies the broader definition. We therefore conclude that the definition of periglacial is not contentious. Not only are we comfortable with the idea of periglacial processes, but equally there is agreement over the approximate extent of past and present periglacial environments, depending on whether the narrower or broader definition above is used. The situation is not so clear in the context of the terms “proglacial” and “paraglacial”, especially since the publication of a major paper on paraglacial geomorphology (Ballantyne 2002a). French (2007) has a nice discussion on this issue in which he notes that the proglacial environment, which refers specifically to ice-marginal conditions, is a periglacial environment in the original sense of Lozinski. Proglacial systems, sediment-landform associations and landform assemblages