Cold-Climate Granite Landscapes

Inselbergs, tors, boulder fields, and pediments are repetitive landforms of many low- to mid-latitude granite landscapes, whether in humid or in arid environments. Although there have been attempts to link these landforms to certain specific climatic environments, their actual distribution, as shown in the preceding chapters, speaks clearly for minor climatic control in their development. Therefore, identification of a ‘typical’ granite rainforest, or savanna, or desert landscape does not seem possible. Each of these environments is known to host a variety of distinctive landscapes supported by granite, which will be explored in the next chapter. Likewise, cold environments in high latitudes have long been considered as having a very distinctive geomorphology, in which the factor of rock control matters little, but repeated freezing and thawing is critical. This view is difficult to maintain any longer, especially in the light of recent progress in periglacial geomorphology. The effects of glaciation are more evident, but even there the role of bedrock must not be neglected and formerly glaciated granite terrains do show certain specific features. Many granite terrains are located in cold environments, or have experienced cold-climate conditions in the relatively recent past of the Pleistocene. Therefore, it is reasonable to expect that their geomorphic evolution has been influenced by a suite of surface processes characteristic of such settings, collectively termed as ‘periglacial’. Present-day periglacial conditions typify such granite areas as the uplands of Alaska, Yukon, and the northern Rocky Mountains, much of the Canadian Shield, coastal strips of Greenland, northern Scandinavia, extensive tracts of Siberia, and the Tibetan Plateau. Granite areas located further south, in the British Isles, the Iberian Peninsula, the Massif Central, the Harz Mountains, and the Bohemian Massif, were affected by periglacial conditions for most of the Pleistocene. In fact, the most elevated parts of these mountains and uplands experience a mild periglacial environment even today and winter temperatures may remain below 0°C for weeks. The efficacy of present-day frost action is however limited by the insulating snow cover. Some of the granite areas of the southern hemisphere are, or were, within the periglacial realm too.