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Lumparn (fi. ''Lumpari'') is a large
bay A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a ''gulf'', ''sea'', ''sound'', or ''bight''. A ''cove'' is a small, ci ...
devoid of islands in the main island of
Ã…land Ã…land ( , ; ) is an Federacy, autonomous and Demilitarized zone, demilitarised region of Finland. Receiving its autonomy by a 1920 decision of the League of Nations, it is the smallest region of Finland by both area () and population (30,54 ...
,
Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...
, bordered by Sund to the north,
Lumparland Lumparland is a municipality of Ã…land, an autonomous territory of Finland. It is the smallest municipality on mainland Ã…land. The municipality has a population of () and covers an area of of which is water. The population density is . The mu ...
to the east,
Lemland Lemland is a municipality of Åland, an autonomous territory of Finland. The municipality has a population of () and covers an area of of which is water. The population density is . The municipality is unilingually Swedish. The Lemström ch ...
to the south and
Jomala Jomala is a municipality of Ã…land, an autonomous territory of Finland. In terms of population, it is the next largest after Mariehamn, the capital of Ã…land. The municipality has a population of () and covers an area of of which is water. The ...
to the west.


Description

Most of the bay fills a nine kilometer wide
impact structure An impact structure is a generally circular or craterlike geologic structure of deformed bedrock or sediment produced by impact on a planetary surface, whatever the stage of erosion of the structure. In contrast, an impact crater is the surface e ...
. The structure is estimated to be about 1000 million years old (
Proterozoic The Proterozoic ( ) is the third of the four geologic eons of Earth's history, spanning the time interval from 2500 to 538.8 Mya, and is the longest eon of Earth's geologic time scale. It is preceded by the Archean and followed by the Phanerozo ...
). The depression was originally believed to be a
rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben ...
. Extraterrestrial origin was first proposed in 1979, but not until 1993 was the impact structure finally confirmed. Long
shatter cones Shatter cones are rare geological features that are only known to form in the bedrock beneath meteorite impact craters or underground nuclear explosions. They are evidence that the rock has been subjected to a shock with pressures in the ran ...
have been discovered in the southwestern part of the bay. The remains of the crater are filled with sediments. Between
Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
sediments and crushed rapakivi granite
bedrock In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of bed ...
there is a layer of
Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...
(
Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...
)
limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
s. This makes Lumparn one of the few places in Finland where
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
s have been found. The bay has also previously been referred to as ''Lumpari'' in some Finnish documents, though the
Research Institute for the Languages of Finland The Institute for the Languages of Finland, better known as Kotus, is a governmental linguistic research institute of Finland geared to studies of Finnish, Swedish (cf. Finland Swedish), the Sami languages, Romani language, as well as Finnish S ...
does not list ''Lumpari'' as in current usage.Svenska Ortnamn i Finland
, The Research Institute for the Languages of Finland, see "Lumparn"


Gallery


See also

* Impact craters in Finland


References


External links


Lumparn impact structure
(archived link) *