Periglacial

Periglacial zones and climates

The 'zonal' concept of physical geography has its roots in the work of the German geomorphologist Carl Troll within the general idea of climatic geomorphology. The definition of what a periglacial zone is not clear-cut but a conservative estimate is that a quarter of Earth's land surface has periglacial conditions. Beyond this quarter an additional quarter or fifth of Earth's land surface had periglacial conditions at some time during the Pleistocene. In the northern hemisphere larger swathes of northern Asia and northern North America are periglaciated. In Europe parts of Fennoscandia, Iceland, northern European Russia and Svalbard. In addition Alpine areas in the non-arctic northern hemisphere might also be subject to periglaciation. A major outlier in the northern hemisphere is the Tibetan Plateau that stands out by its size and low-latitude location. In the southern hemisphere parts of the Andes, the ice-free areas of Antarctica and the sub-Antarctic islands are periglaciated. In 1935, Melik discovered that frost weathering had been a very successful geomorphic process in non-glaciated regions of the Slovenian Alps throughout the Pleistocene. The word "periglacial" was not well-known at the time so he merely emphasized enhanced transit of scree down the slopes in relation to mass movement processes. In 1963, Melik introduced the term "periglacial" in the second version of the general section of his Slovenia book, where he also provided a more thorough description of the dominant geomorphic processes on the slopes.