Paasselkä
Encyclopedia
Paasselkä is an oval-shaped lake formed in an eroded impact crater
in Southern Savonia
, Finland
. The lake, which is a part of Orivesi, which is in turn part of the Greater Saimaa
, is devoid of islands which makes it different from other lakes in the region. Paasselkä is also unusually deep, 75 m at the deepest point.
The Paasselkä impact occurred about 229 million years ago (Triassic
) and affected Paleoproterozoic
crystalline rocks and some overlying sandstones of the Baltic Shield
. Because of the unusual shape and associated magnetic
anomalies, Paasselkä was suspected to have an impact origin long until it was confirmed after a deep drilling
in 1999 making it the ninth known impact crater in Finland. Unlike many Finnish craters, it does not seem to have been buried under layers of sediment
.
, is a claimed will-o'-the-wisp
phenomenon which sometimes occurs at the lake and the marsh and forest area in the immediate vicinity. One has described the light as a ball that moves at different speeds, or are completely at rest, and sometimes there are several spheres. The phenomenon has been known for a long time, written down from the 18th century but has been there "always", and is part of the local folk tales, which have given the name "devils". The locals thought the shining spheres were created by evil beings. The magnetic anomalies in connection with the impact crater might be related to the phenomenon.
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
in Southern Savonia
Southern Savonia
Southern Savonia is a region in the south-east of Finland. It borders to the regions Northern Savonia, North Karelia, South Karelia, Kymenlaakso, Päijänne Tavastia, and Central Finland...
, Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
. The lake, which is a part of Orivesi, which is in turn part of the Greater Saimaa
Saimaa
Saimaa is a lake in southeastern Finland. At approximately , it is the largest lake in Finland, and the fourth largest in Europe. It was formed by glacial melting at the end of the Ice Age. Major towns on the lakeshore include Lappeenranta, Imatra, Savonlinna, Mikkeli, Varkaus, and Joensuu. The...
, is devoid of islands which makes it different from other lakes in the region. Paasselkä is also unusually deep, 75 m at the deepest point.
The Paasselkä impact occurred about 229 million years ago (Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
) and affected Paleoproterozoic
Paleoproterozoic
The Paleoproterozoic is the first of the three sub-divisions of the Proterozoic occurring between . This is when the continents first stabilized...
crystalline rocks and some overlying sandstones of the Baltic Shield
Baltic Shield
The Baltic Shield is located in Fennoscandia , northwest Russia and under the Baltic Sea. The Baltic Shield is defined as the exposed Precambrian northwest segment of the East European Craton...
. Because of the unusual shape and associated magnetic
Earth's magnetic field
Earth's magnetic field is the magnetic field that extends from the Earth's inner core to where it meets the solar wind, a stream of energetic particles emanating from the Sun...
anomalies, Paasselkä was suspected to have an impact origin long until it was confirmed after a deep drilling
Boring (earth)
Boring is drilling a hole, tunnel, or well in the earth.-Earth boring:Boring is used for a wide variety of applications in geology, agriculture, hydrology, civil engineering, and oil and natural gas industries...
in 1999 making it the ninth known impact crater in Finland. Unlike many Finnish craters, it does not seem to have been buried under layers of sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
.
Light phenomenon
Päässelän pirut, or Paasselkä devilsPaasselkä devils
Paasselkä devils are light phenomena sometimes appearing at Lake Paasselkä, Finland and swampy and forested areas nearby the lake.Paasselkä is a lake formed in an impact crater. There is a magnetic anomaly in the centre of the lake....
, is a claimed will-o'-the-wisp
Will-o'-the-wisp
A will-o'-the-wisp or ignis fatuus , also called a "will-o'-wisp", "jack-o'-lantern" , "hinkypunk", "corpse candle", "ghost-light", "spook-light", "fairy light", "friar's lantern", "hobby lantern", "ghost orb", or simply "wisp", is a ghostly light or lights sometimes seen at night or twilight over...
phenomenon which sometimes occurs at the lake and the marsh and forest area in the immediate vicinity. One has described the light as a ball that moves at different speeds, or are completely at rest, and sometimes there are several spheres. The phenomenon has been known for a long time, written down from the 18th century but has been there "always", and is part of the local folk tales, which have given the name "devils". The locals thought the shining spheres were created by evil beings. The magnetic anomalies in connection with the impact crater might be related to the phenomenon.