Permafrost and periglacial processes
Permafrost is frozen ground which remains frozen for at least two consecutive years. Most of present day permafrost formed during or since the last ice age. On top of the permafrost is a thin layer of soil that thaws each summer and refreezes each winter - the active layer. The term "periglacial" was first used by the Polish geologist Walezy Łoziński in his publication in 1909. Periglacial environments are located where freezing and thawing together with permafrost underneath modify the landscape in a significant manner. The most widespread periglacial landforms are tundra polygons, which are formed by thermal-contraction cracking and divide the ground surface up into polygonal nets. Thawing permafrost has a huge impact on landscapes, topography, local ecosystems and economies.During this lecture students will develop understanding of periglacial landforms and geomorphology. The update geomorhological definitions and terminologies will be supported with photographs of periglacial landforms from different parts of the world.