Glacial and Periglacial Environments

Abstract

Traditionally, glacial and periglacial geomorphology has not featured prominently in discussions about the physical geography of the Mediterranean basin. It is now clear, however, that on numerous occasions during the Pleistocene, and to a lesser extent during the Little Ice Age (LIA), glacial and periglacial activity was widespread in many of the region’s mountain ranges (Hughes et al. 2006a; Hughes and Woodward 2008). Even today, small glaciers and active periglacial features can be found on the highest peaks. Many mountain landscapes in the Mediterranean basin are therefore the product of glacial and periglacial processes that have fluctuated in intensity and spatial extent through the Quaternary. Glacial processes are defined here as those occurring as a result of dynamic glacier ice. The periglacial zone is sometimes defined as non-glacial areas where the mean annual temperature is less than 3°C (French 1996: 20). However, cryogenic processes can be important in landform development, even in areas of shallow frost over a wide range of mean annual temperatures. Thus, the term ‘periglacial’ is applied here to areas characterized by cold-climate processes—where frost and nival processes are important—but where glaciers are absent. Glacial and periglacial processes in the uplands can exert considerable influence upon geomorphological systems at lower elevations. Fluvial systems, for example, over a range of timescales have been shown to be especially sensitive to changes in sediment supply and water discharge from glaciated mountain headwaters (Gurnell and Clark 1987; Woodward et al. 2008). Nonetheless, the geomorphological impacts of glaciation are most clearly evident in the Mediterranean mountains where the erosional and depositional legacy is frequently well preserved. Cirques, glacial lakes, icescoured valleys, moraines, pronival ramparts, relict rock glaciers, and other glacial and periglacial features can be found in many Mediterranean mountain ranges (Hughes et al. 2006a). Upland limestone terrains are widespread across the Mediterranean and many of these landscapes have been shaped by a combination of glacial and karstic processes (Chapter 10). In fact, glacio-karst is probably the dominant landscape in many mountain regions, including the Dinaric Alps of Croatia/Bosnia/Montenegro (Nicod 1968), the Cantabrian Mountains of Spain (Smart 1986) and the Pindus Mountains of Greece (Waltham 1978; Woodward et al. 2004; Hughes et al. 2006b).