jääbühikki

Jääbühikki refers to a specific type of rock formation found in glacial environments. It is characterized by ice wedges that form within the soil or sediment. These ice wedges develop through a process of thermal contraction and expansion. In winter, the ground freezes and contracts, creating cracks. In summer, meltwater seeps into these cracks, and when it freezes again, it forms a wedge of ice. Over repeated freeze-thaw cycles, these ice wedges can grow significantly, pushing the surrounding sediment apart and creating a polygonal pattern on the surface, often referred to as patterned ground.

The formation of jääbühikki is indicative of permafrost conditions, where the ground remains frozen for at least two consecutive years. The size and shape of the ice wedges can vary depending on factors such as climate, soil type, and the duration of the freezing period. In some cases, these ice wedges can be several meters deep and wide. When the permafrost thaws, the ice wedges melt, leading to the collapse of the overlying sediment and the formation of distinctive depressions or troughs. These features are important indicators of past and present permafrost activity and are studied by geologists and geographers to understand past climatic conditions and ongoing environmental changes. The term itself is Finnish, with "jää" meaning ice and "bühikki" referring to a wedge or piler.