Lake Cheko (russian: Чеко) is a small

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does in ...

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much lar ...

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part o ...

, near the Podkamennaya Tunguska River, in what is now the Evenkiysky District of the

Krasnoyarsk Krai Krasnoyarsk Krai ( rus, Красноя́рский край, r=Krasnoyarskiy kray, p=krəsnɐˈjarskʲɪj ˈkraj) is a federal subject of Russia (a krai), with its administrative center in the city of Krasnoyarsk, the third-largest city in ...

Dimensions and environs

Lake Cheko is a small bowl-shaped lake. It is about long, wide and deep. In the lake flows the Kimchu River (Russian: кимчу), which flows into the Chunya River (Russian: Чуня), which in turn flows into the

Podkamennaya Tunguska The Podkamennaya Tunguska (russian: Подкаменная Тунгуска, literally ''Tunguska under the stones''; evn, Дулгу Катэнӈа, Ket: Ӄо’ль) also known as ''Middle Tunguska'' or ''Stony Tunguska'', is a river in Krasnoy ...

Possible relation to the Tunguska event

Lake Cheko is roughly north-northwest of the

epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage Before the instrumental pe ...

of the

Tunguska event The Tunguska event (occasionally also called the Tunguska incident) was an approximately 12- megaton explosion that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate (now Krasnoyarsk Krai), Russia, on the morning of June ...

. The lake is inside the blast zone, and in the probable direction of whatever caused the Tunguska event. It has been connected by some scientists to the

and they postulate the lake was created by a chunk of the exploding meteorite that struck the ground. In 2017, that theory was disputed by Russian scientists by proving that the lake is older, possibly even much older, than the Tunguska Event.

Age of the lake

Some scientists have speculated that Lake Cheko was created during the

of 1908, an explosion that destroyed more than of Siberian

taiga Taiga (; rus, тайга́, p=tɐjˈɡa; relates to Mongolic and Turkic languages), generally referred to in North America as a boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruces ...

. It is suggested that the lake, which lies approximately 8 kilometres north-north-west of the event

hypocenter In seismology, a hypocenter or hypocentre () is the point of origin of an earthquake or a subsurface nuclear explosion. A synonym is the focus of an earthquake. Earthquakes An earthquake's hypocenter is the position where the strain energy ...

, was formed by a fragment which struck the ground. More recent evidence suggests at least a portion of the lake is over twice as old as the date of the meteorite.

Other varied evidence

A 1961 investigation estimated the age of the lake to be at least 5000 years, based on meters-thick

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel wh ...

deposits on the lake bed. However, a 2001 paper concluded that the sediments, isotopes, and pollen "suggest that Lake Cheko formed at the time of the Tunguska Event." Their recent research indicates that only a metre or so of the sediment layer on the lake bed is "normal

lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sa ...

ation", indicating a much younger lake of about 100 years. Acoustic-echo soundings of the lake floor offer some further support for the impact hypothesis, revealing a conical shape for the lake bed, which could be consistent with an impact crater. Also, the lake's long axis points to the

of the Tunguska explosion, about 7.0 km away. Magnetic readings also indicate a possible meter-sized chunk of rock below the lake's deepest point, which may be a fragment of the colliding body. In 2008, a BBC News story on the 100th anniversary of the Tunguska Event mentioned that researchers at

Imperial College London Imperial College London (legally Imperial College of Science, Technology and Medicine) is a public research university in London, United Kingdom. Its history began with Prince Albert, consort of Queen Victoria, who developed his vision for a ...

had pointed out that many of the trees surrounding the lake are older than 100 years, which suggests that the lake could not have been created by an impact in 1908. The researchers also pointed out other problems, including the morphology of the lake and the surrounding terrain, the lack of impactor debris and

ejecta Ejecta (from the Latin: "things thrown out", singular ejectum) are particles ejected from an area. In volcanology, in particular, the term refers to particles including pyroclastic materials ( tephra) that came out of a volcanic explosion and magm ...

, noting that the characteristics of the impactor required by the impact theory are inconsistent with existing models of the known features of the event. However, researchers from the

University of Bologna The University of Bologna ( it, Alma Mater Studiorum – Università di Bologna, UNIBO) is a public research university in Bologna, Italy. Founded in 1088 by an organised guild of students (''studiorum''), it is the oldest university in continuo ...

investigated the lake bed in 2009 and, based on evidence such as sedimentation, reaffirmed the conclusions of the 2001 paper, that Lake Cheko formed at the time of the Tunguska Event. Additional research by Russian scientists in 2017 appeared to contradict a purely Tunguska Event-based formation theory. Core samples of sediment taken from the deepest part of the lake demonstrated an age of up to 280 years, suggesting that at least a portion of the lake existed prior to the meteorite striking.

References

{{reflist, refs= {{cite journal , last = Florenskiy , first = K. P. , authorlink = Kirill Florensky , title = Preliminary results from the 1961 combined Tunguska meteorite expedition , journal = Meteoritica , volume = 23 , pages = 3–29 , year = 1963 , url = http://abob.libs.uga.edu/bobk/tungmet.html , accessdate = 2007-06-26 {{cite web, url=http://www-th.bo.infn.it/tunguska/terranova.html , title=Sediments from Lake Cheko (Siberia), a possible impact crater for the 1908 Tunguska Event , last=Gasperini , first=Luca, year=2009 , accessdate=30 June 2010, display-authors=etal {{cite journal , last1=Gasperini , first1=Luca , last2=Bonatti , first2=Enrico , last3=Albertazzi , first3=Sonia , last4=Forlani , first4=Luisa , last5=Accorsi , first5=Carla A. , last6=Longo , first6=Giuseppe , last7=Ravaioli , first7=Mariangela , last8=Alvisi , first8=Francesca , last9=Polonia , first9=Alina , last10=Sacchetti , first10=Fabio , last11=Polonia , first11=Alina , last12=Sacchetti , first12=Fabio , date=December 2009 , title=Sediments from Lake Cheko (Siberia), a possible impact crater for the 1908 Tunguska Event , journal=Terra Nova , volume=21 , issue=6 , pages=489–494 , doi=10.1111/j.1365-3121.2009.00906.x , url=http://www3.interscience.wiley.com/cgi-bin/fulltext/122652721/PDFSTART, accessdate=30 June 2010, display-authors=8 , bibcode=2009TeNov..21..489G, doi-access=free {{dead link, date=February 2019, bot=medic{{cbignore, bot=medic {{cite journal , last = Gasperini , first = L., title = Geophysical/sedimentological study of a lake close to the centre of the great 1908 Siberian (Tunguska) Explosion , journal = NGF Abstracts and Proceedings , issue = 1 , pages = 29–30 , year = 2001 , url = http://www-th.bo.infn.it/tunguska/GasperiniSvalbard.pdf , accessdate = 2008-05-27 , display-authors=etal {{cite journal , last1 = Gasperini , first1 = L. , title = Reply - Lake Cheko and the Tunguska Event: impact or non-impact? , journal = Terra Nova , volume = 20 , issue = 2 , pages = 169–172 , date=April 2008 , doi = 10.1111/j.1365-3121.2008.00792.x , last2 = Bonatti , first2 = Enrico , last3 = Longo , first3 = Giuseppe , display-authors=etal, bibcode = 2008TeNov..20..169G {{cite journal , last = Gasperini , first = L., title = The Tunguska Mystery , journal = Scientific American , volume = 298, issue = 6, pages = 80–86 , date=June 2008 , display-authors=etal, doi = 10.1038/scientificamerican0608-80, pmid = 18642546 , bibcode = 2008SciAm.298f..80G {{cite web , last = Rincon , first = Paul , title = Fire in the sky: Tunguska at 100 , work = BBC News , url = http://news.bbc.co.uk/1/hi/sci/tech/7470283.stm , accessdate = 2008-07-01 , date=2008-06-30 {{cite journal, last1=Collins , first1 = G. S. , last2=Artemieva , first2=N. , last3=Wünnemann , first3=K. , last4=Bland , first4=P. A. , last5=Reimold , first5=W. U. , last6=Koeberl , first6=C. , title=Evidence that Lake Cheko is not an impact crater , journal=Terra Nova , volume=20 , issue=2 , pages=165–168 , doi=10.1111/j.1365-3121.2008.00791.x , year = 2008 , display-authors=etal, bibcode=2008TeNov..20..165C

External links