Paasselkä

Paasselkä Impact Structure

Paasselkä is an eroded impact crater located in Southern Savonia, Finland, which has formed an oval-shaped lake. This unique geological feature is part of the Orivesi lake, which in turn belongs to the Greater Saimaa lake system. Unlike many other lakes in the region, Paasselkä is devoid of islands and is noted for its unusual depth, reaching a maximum of 75 meters.

Geological History and Confirmation

The impact event that created Paasselkä is estimated to have occurred approximately 1800 million years ago, during the Statherian period of the Paleoproterozoic Era. The impact affected the underlying Paleoproterozoic crystalline rocks and some overlying sandstones of the Baltic Shield. For a long time, the unusual shape of the lake and associated magnetic anomalies suggested an impact origin. This hypothesis was confirmed after deep drilling operations were conducted in 1999, solidifying Paasselkä's status as the ninth known impact crater in Finland. Notably, unlike many Finnish craters, Paasselkä does not appear to have been buried under significant layers of sediment.

Local Folklore: Paasselkä Devils

Paasselkä is also associated with a local folklore phenomenon known as 'Paasselkä devils' (Paasselän pirut). This claimed will-o'-the-wisp phenomenon is described as spheres of light that sometimes appear at the lake and in the surrounding marsh and forest areas. Documented since the 18th century, these shining spheres are part of local folk tales, where they were attributed to evil beings. It is speculated that the magnetic anomalies present within the impact crater might be related to the occurrence of this mysterious phenomenon.