Abstract:In broad terms, permafrost-related landforms can be divided into those associated with either the growth (aggradation) or thaw (degradation) of permafrost. This chapter considers the characteristic la...In broad terms, permafrost-related landforms can be divided into those associated with either the growth (aggradation) or thaw (degradation) of permafrost. This chapter considers the characteristic landforms associated with permafrost aggradation. All the phenomena result primarily from permafrost aggradation in saturated sand with pore-water expulsion in an open hydrological system. Thermal-contraction-crack polygons are some of the most distinct surface features of the periglacial landscape. They reflect the formation of permafrost and are variously referred to as tundra polygons, frost-fissure polygons, ice-wedge polygons, or 'Taimyr' polygons. The chapter describes the ice and sand wedges that form in present-day permafrost environments. When discussing actively-forming wedges, a useful approach is to consider the direction of their growth relative to the land surface. Hydrostatic system pingos result from pore-water expulsion caused by permafrost aggradation in water-saturated sandy sediment. Polygonal nets are less well developed in poorly-lithified bedrock and usually absent from terrain developed in hard igneous and metasedimentary rocks.Read More
Publication Year: 2017
Publication Date: 2017-10-27
Language: en
Type: other
Indexed In: ['crossref']
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