Sääksjärvi
Encyclopedia
Sääksjärvi is a lake
in Kokemäki
, Satakunta, western Finland
, east from the town of Pori
. The lake is notable because it overlies an impact crater
.
The crater is 5 kilometres (3 mi) in diameter and is completely buried under the lake and is not visible at the surface. The age of the impact structure is estimated to be about 543 ± 12 Ma (million years ago), at the boundary between the Ediacaran
and Cambrian
periods. There are impactite
rocks in the southwestern region from the crater confirming its extraterrestrial origin. At the time of its discovery, only one impact crater (Lappajärvi
) was known in Finland.
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
in Kokemäki
Kokemäki
Kokemäki is a town and municipality of Finland.It is located in the province of Western Finland and is part of the Satakunta region. The town has a population of and covers an area of of which is water...
, Satakunta, western 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...
, east from the town of Pori
Pori
Pori is a city and municipality on the west coast of Finland. The city is located some from the Gulf of Bothnia, on the estuary of the Kokemäenjoki river, which is the largest in Finland. Pori is the most important town in the Satakunta region....
. The lake is notable because it overlies an impact crater
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...
.
The crater is 5 kilometres (3 mi) in diameter and is completely buried under the lake and is not visible at the surface. The age of the impact structure is estimated to be about 543 ± 12 Ma (million years ago), at the boundary between the Ediacaran
Ediacaran
The Ediacaran Period , named after the Ediacara Hills of South Australia, is the last geological period of the Neoproterozoic Era and of the Proterozoic Eon, immediately preceding the Cambrian Period, the first period of the Paleozoic Era and of the Phanerozoic Eon...
and Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
periods. There are impactite
Impactite
Impactite is an informal term describing a rock created or modified by the impact of a meteorite. The term encompasses shock-metamorphosed target rocks, melts and mixtures of the two, as well as sedimentary rocks with significant impact-derived components .-Some localities:*Nördlinger Ries...
rocks in the southwestern region from the crater confirming its extraterrestrial origin. At the time of its discovery, only one impact crater (Lappajärvi
Lake Lappajärvi
Lappajärvi is a lake in Finland, in the municipalities of Lappajärvi, Alajärvi and Vimpeli. It is formed in a wide meteorite crater. The age of the crater is estimated to be 73.3 million years old —the upper Cretaceous period. The lake is part of Ähtävänjoki basin together with Lake Evijärvi that...
) was known in Finland.