View source for Earth:Kaali crater

{{Short description|Group of nine impact craters in Estonia}}
{{Infobox terrestrial impact site
| name          = Kaali crater
| other_name    = 
| photo         = 
| photo_caption = 
| map           = Estonia
| map_caption   = Impact location in Estonia
| coordinates   = {{coord|58|22|22|N|22|40|10|E|region:EE-39_type:landmark_scale:50000|display=inline}}
| confidence    = Confirmed
| diameter      = {{cvt|110|m||}}
| depth         = 
| age           = 3237+/-10 <sup>14</sup>C yr BP
| exposed       = 
| drilled       = 
| imp_size      = 
| bolide        = 
| country       = Estonia
| state         = 
}}
[[Image:Kaali-crater-saaremaa-estonia-aug-2007.jpg|thumb|right|The crater as viewed from near the rim]]
[[Image:Kaali main crater on 2005-08-10.3.jpg|thumb|right|The main crater is nearly circular. When the water level is low, rocks can be seen penetrating the surface: in the middle of the crater.]]
[[Image:KaaliDolomite.jpg|thumb|right|Tilted [[Earth:Dolomite (rock)|dolomite]] bedrock in the walls of the main crater]]

'''Kaali''' is a group of nine [[Astronomy:Meteorite|meteorite]] [[Astronomy:Impact crater|crater]]s in the village of Kaali on the Estonian island of Saaremaa.<ref name=raukas>{{Cite Earth Impact DB | name = Kaalijärv | linkname = kaalijarv | accessdate = 2008-12-30 }}</ref> Most recent estimates put its formation shortly after 1530–1450 BC (3237+/-10 <sup>14</sup>C yr BP).<ref>{{Cite journal|last1=Losiak|first1=A.|last2=Wild|first2=E. M.|last3=Geppert|first3=W. D.|last4=Huber|first4=M. S.|last5=Jõeleht|first5=A.|last6=Kriiska|first6=A.|last7=Kulkov|first7=A.|last8=Paavel|first8=K.|last9=Pirkovic|first9=I.|date=2016-04-01|title=Dating a small impact crater: An age of Kaali crater (Estonia) based on charcoal emplaced within proximal ejecta|journal=Meteoritics & Planetary Science|language=en|volume=51|issue=4|pages=681–695|doi=10.1111/maps.12616|issn=1945-5100|bibcode=2016M&PS...51..681L|doi-access=free}}</ref> It was created by an [[Astronomy:Impact event|impact event]] and is one of the few impact events that has occurred in a populated area (other ones are: Henbury craters and Carancas crater).

Before the 1930s there were several hypotheses about the origin of the crater, including theories involving [[Earth:Volcanology|vulcanism]] and [[Earth:Karst|karst]] processes. Its meteoritic origins were first conclusively demonstrated by Ivan Reinvald<ref>{{Cite web|url=http://entsyklopeedia.ee/artikkel/reinwald_ivan|title = Reinwald, Ivan - Eesti Entsüklopeedia}}</ref> in 1928, 1933 and 1937.

==Formation==

The impact is thought to have happened in the [[Earth:Holocene|Holocene]] period, around 3,500 years ago.<ref name="Bianca">Bianca Mikovitš. [http://maaleht.delfi.ee/news/maaleht/uudised/teadlaste-too-tulemus-kaali-kraatri-vanuse-maaramisel-uhtib-vana-regilauluga?id=73512561 Teadlaste töö tulemus Kaali kraatri vanuse määramisel ühtib vana regilauluga] Maaleht, January 26, 2016</ref> The estimates of the age of the Kaali impact structure (Saaremaa Island, Estonia) provided by different authors vary by as much as 6,000 years, ranging from ~6,400 to ~400 years before current era (BCE). Analysis of [[Chemistry:Silicate minerals|silicate]] spherules in Estonian bogs show that the possible age of the impact craters could be approximately 7,600 years.<ref>{{Cite journal|last=Raukas |first= A. | display-authors=0|date=1995|title=On the age of the meteorite craters at Kaali (Saaremaa Island, Estonia)|journal=Proceedings of Estonian Academy of Sciences, Geology 44:177–183.}}</ref> A study based on elevated [[Chemistry:Iridium|iridium]] signal in a nearby bog suggested the much younger age of 4th century BC.<ref>{{Cite journal|last1=Veski|first1=Siim|last2=Heinsalu|first2=Atko|last3=Kirsimäe|first3=Kalle|last4=Poska|first4=Anneli|last5=Saarse|first5=Leili|date=2001-10-01|title=Ecological catastrophe in connection with the impact of the Kaali meteorite about 800–400 B.C. on the island of Saaremaa, Estonia|journal=Meteoritics & Planetary Science|language=en|volume=36|issue=10|pages=1367–1375|doi=10.1111/j.1945-5100.2001.tb01830.x|issn=1945-5100|bibcode=2001M&PS...36.1367V|doi-access=free}}</ref> The craters were formed by a meteor with an estimated impact velocity of between {{cvt|10|and|20|km/s}} with a total mass of between 20 and 80 metric tonnes. According to some researchers the meteor arrived from the north-east.<ref name=wonder>{{cite web|url=http://www.wondermondo.com/Countries/E/Estonia/Saaremaa/Kaali.htm|title=Kaali Crater|publisher=Wondermondo|date=2012-11-22}}</ref>

At an altitude of {{cvt|5|to|10|km|ft|-4|spell=in}}, the meteor broke into pieces and fell to the Earth in fragments, the greatest of which produced a crater with a diameter of {{cvt|110|m||}} and a depth of {{cvt|22|m||}}. The explosion removed approximately {{cvt|81000|m³||}} of dolomite and other rocks and formed a {{cvt|7|to|8|km|ft|-4}} tall, extremely hot gas flow. Vegetation was incinerated up to {{cvt|6|km||}} from the impact site.<ref name=wonder />

Kaali Lake ({{lang-et|Kaali järv}}) is on the bottom of this crater. Eight smaller craters are also associated with this bombardment. Their diameters range from {{cvt|12|to|40|m}} and their respective depths vary from {{convert|1|to|4|m|ft|spell=in}}. They are all within {{convert|1|km|spell=in|}} of the main crater.

==Effects==
According to the theory of more recent impact, Estonia at the time of impact was in the Nordic Bronze Age and the site was forested with a small human population. The impact energy of about 80 TJ (20 kilotons of TNT) is comparable with that of the [[Physics:Hiroshima bomb (unit)|Hiroshima bomb]] blast. It incinerated forests within a {{cvt|6|km|spell=in|}} radius.<ref name="MPS">{{cite journal
| title = Ecological catastrophe in connection with the impact of the Kaali meteorite about 800–400 BC on the island of Saaremaa, Estonia
|author1=Siim Veski |author2=Atko Heinsalu |author3=Kalle Kirsimäe |author4=Anneli Poska |author5=Leili Saarse | journal = Meteoritics & Planetary Science
| volume = 36
| issue =  3
| pages = 1367–1375
| year = 2001
| url = http://www.gi.ee/pdfid/10200.pdf
| doi = 10.1111/j.1945-5100.2001.tb01830.x|bibcode = 2001M&PS...36.1367V | doi-access = free}}</ref>

==In mythology==

Scholars, such as Karl Kello,<ref>{{Cite book|last=Kello, Karl.|url=https://www.worldcat.org/oclc/162329217|title=The pharaoh of the north|date=2005|publisher=Tallinna Raamatutrükikoda|isbn=9949-13-080-8|location=[Tallinn]|oclc=162329217}}</ref> maintain that the event figured prominently in regional mythology. It was, and still is, considered a sacred lake. There is archaeological evidence{{clarify|date=February 2020}} that it may well have been a place of ritual sacrifice. At some point during the early [[History:Iron Age|Iron Age]], the lake was surrounded by a stone wall {{cvt|470|m||}} long, with a median width of about {{cvt|2.5|m|ft|}} and an average height of {{cvt|2.0|m|ft|}}.{{Citation needed|date=January 2011}}

Finnish mythology has stories that may [[Social:Folk memory|originate]] with the formation of Kaali. One of them is in runes 47, 48 and 49 of the Kalevala epic: Louhi, the evil wizard, steals the Sun and fire from people, causing total darkness. [[Religion:Ukko|Ukko]], the god of the sky, orders a new Sun to be made from a spark. The virgin of the air starts to make a new Sun, but the spark drops from the sky and hits the ground. This spark goes to an "Aluen" or "Kalevan"<ref name="Silverwhite">{{cite book
 | author = Lennart Meri
 | year = 1976
 | title = Hõbevalge (Silverwhite)
 | publisher = Eesti Raamat
 | location = [[Place:Tallinn|Tallinn]], Estonia
 | title-link =Silverwhite
 }}</ref> lake and causes its water to rise. Finnish heroes see the ball of fire falling somewhere "behind the Neva river" (the direction of Estonia from [[Place:Karelia|Karelia]]). The heroes head in that direction to seek fire, and they finally gather flames from a forest fire.

According to a theory first proposed by Lennart Meri, it is possible that Saaremaa was the legendary [[Unsolved:Thule|Thule]] island, first mentioned by ancient Greek geographer [[Biography:Pytheas|Pytheas]], whereas the name "Thule" could have been connected to the Finnic word ''tule'' ("(of) fire") and the folklore of Estonia, which depicts the birth of the crater lake in Kaali. Kaali was considered the place where "The sun went to rest."<ref name="Silverwhite" />

[[File:Kaali crater panorama.jpg|thumb|center|700px|The main crater]]

==Namesake==
The asteroid [[Astronomy:4227 Kaali|4227 Kaali]] is named after it. Except for their names, there is no connection between this asteroid and the crater.

== Meteoritic iron artefacts ==
In 2023, archaeologists analyzed an arrowhead from Switzerland made of meteoritic iron whose composition suggested its origin from the Kaali meteorite.<ref>{{Cite journal |last1=Hofmann |first1=Beda A. |last2=Schreyer |first2=Sabine Bolliger |last3=Biswas |first3=Sayani |last4=Gerchow |first4=Lars |last5=Wiebe |first5=Daniel |last6=Schumann |first6=Marc |last7=Lindemann |first7=Sebastian |last8=García |first8=Diego Ramírez |last9=Lanari |first9=Pierre |last10=Gfeller |first10=Frank |last11=Vigo |first11=Carlos |last12=Das |first12=Debarchan |last13=Hotz |first13=Fabian |last14=von Schoeler |first14=Katharina |last15=Ninomiya |first15=Kazuhiko |date=September 2023 |title=An arrowhead made of meteoritic iron from the late Bronze Age settlement of Mörigen, Switzerland and its possible source |journal=Journal of Archaeological Science |language=en |volume=157 |pages=105827 |doi=10.1016/j.jas.2023.105827|doi-access=free |hdl=20.500.11850/625369 |hdl-access=free }}</ref>

==References==
{{Reflist}}
*{{cite journal
| title = Kaali Craters of Estonia and Their Meteoritic Material
| author = Tiirmaa, R.
| journal = Meteoritics
| volume = 27
| issue =  3
| pages = 297
| year = 1992
| bibcode = 1992Metic..27Q.297T}}
*{{cite book
| title = The Structure and Age of the Kaali Main Crater, Island of Saaremaa, Estonia
|author1=Anto Raukas |author2=J.-M. Punning |author3=T. Moora |author4=Ü. Kestlane |author5=A. Kraut | journal = Impact Studies
| issue =  2
| pages = 341–355
| year = 2005
| doi = 10.1007/3-540-27548-7_13|isbn=978-3-540-24181-2 }}

==External links==
*[http://www.saaremaa.ee/index.php?option=com_content&view=article&id=592 About Kaali crater on the official Saaremaa website]
*[http://www.7is7.com/otto/estonia/kaali.html Photos of the Kaali crater]
*[https://books.google.com/books?id=2zRK6DCWyq0C&dq=dobele+crater&pg=PA341 Impact tectonics]
*[http://www.estonia360.ee/kaali/ Interactive panoramic aerial view of the Kaali crater area]

{{Coord|58|22|22|N|22|40|10|E|region:EE-39_type:landmark_scale:50000|display=title}}
{{S-start}}
{{s-ach|rec}}
{{succession box|
  before=Henbury|
  title=The last [[Astronomy:Impact event|impact event]] on [[Astronomy:Earth|Earth]]|
  years=1300 BC – present| after=Incumbent}}
{{S-end}}
{{Impact cratering on Earth}}


{{DEFAULTSORT:Kaali Crater}}
[[Category:Impact crater lakes]]

{{Sourceattribution|Kaali crater}}