List of unconfirmed impact craters on Earth

This list of unconfirmed impact craters on Earth includes only unconfirmed and theoretical impact sites that have appeared several times in the literature, or endorsed by the Impact Field Studies Group, but have not yet been confirmed by the Earth Impact Database.

Unconfirmed impact craters

The following are officially considered "unconfirmed". Due to stringent requirements regarding evidence and peer-reviewed publication, newly discovered craters, or those where collecting evidence is difficult, generally are known for some time before becoming listed.

Zerelia West and East

Topographic image of Iturralde Crater

False-colour Landsat image of Darwin Crater (arrowed)

Indochina

Younger than one million years old

The first table contains unconfirmed craters younger than one million years old and at least 100 meters in diameter. The Cheko crater is thought to be the result of the famous Tunguska event. There is a highly speculative conjecture about the Sirente impact (c. 320 ± 90 AD) and its effect on the Roman empire.^[1] The Burckle crater and Umm al Binni structure are proposed to be behind the floods that affected Sumerian civilization.^[2][3] The age of the Bloody Creek crater is disputed, with some evidence suggesting it hit glacier ice 12000 years ago, coeval with the Younger Dryas.^[4]

Name	Location	Diameter (km)	Age (thousand years)	Coordinates
Curuçá astrobleme	Amazonas, Brazil	1.0	0.08 (c. 1930 AD)	4°26′S 71°24′W / 4.433°S 71.400°W
Cheko	Siberia, Russia	0.5	0.1 (c. 1900 AD)	60°57′50″N 101°51′36″E / 60.964°N 101.86°E
Mahuika	offshore of New Zealand	20	0.6 (c. 1400 AD)	48°18′S 166°24′E / 48.3°S 166.4°E
Sirente	Italy	0.1	1.7 (c. 320 ± 90 AD)	42°10′38″N 13°35′45″E / 42.17722°N 13.59583°E
Umm al Binni	Iraq	3.4	5 (c. 3000 BC)	31°14′29″N 47°06′21″E / 31.24139°N 47.10583°E
Burckle	Indian Ocean	30	5 (c. 3000 BC)	30°52′S 61°22′E / 30.86°S 61.36°E
Zerelia West[5]	Thessaly, Greece	0.2	7	39°09′48″N 22°42′32″E / 39.16333°N 22.70889°E
Zerelia East[5]	Thessaly, Greece	0.1	7	39°09′43″N 22°42′51″E / 39.16194°N 22.71417°E
Bloody Creek	Nova Scotia, Canada	0.4	12?[4]	44°45′N 65°14′W / 44.750°N 65.233°W
Iturralde	Bolivia	8.0	11-30	12°35′S 67°40′W / 12.583°S 67.667°W
Brushy Creek Feature[6]	Louisiana, USA	2.0	11-30	30°46′05″N 90°44′06″W / 30.768°N 90.735°W
Hickman Crater	Western Australia	0.3	10-100	23°2′13.4″S 119°40′59.3″E / 23.037056°S 119.683139°E
Sithylemenkat[7]	Alaska	12	30?[8]	66°07′34″N 151°23′20″W / 66.12611°N 151.38889°W
La Dulce crater[9]	Argentina	2.8	445?
Australasian	Indochina	100?[10]	800
Darwin Crater	Tasmania	1.2	816	42°19′S 145°40′E / 42.317°S 145.667°E
Pantasma	Nicaragua	10	820?[11]	13°22′N 85°57′W / 13.37°N 85.95°W

As the trend in the Earth Impact Database for about 25 confirmed craters younger than 800,000 years show that none is more than 2 km in diameter (except the 4 km Rio Cuarto), the chances that two large craters, Mahuika (20 km) and Burckle (30 km), forming within the last few millennia has been met with skepticism.^[12][13][14]

However, the source of the enormous Australasian strewnfield (c. 800 ka) is suggested to be a crater about 100 km across somewhere in Indochina,^[10][15] with Hartung and Koeberl (1994) proposing the elongated 100 km x 35 km Tonlé Sap lake in Cambodia (visible in the map at the side)^[16] as a suspect structure.

Mahas crater

Ramgarh crater

Decorah crater

Rubielos de la Cérida

Kebira Crater

Wembo-Nyama ring structure

Duolun crater

The Nastapoka (Hudson Bay) arc of Quebec (in red).

Wilkes Land crater in Antarctica

Older than one million years old

The 41 craters in the table below are either older than 1 Ma, or have an unknown age.

Name	Location	Diameter (km)	Age (million years)	Coordinates
Alamo bolide impact	Nevada, USA	?	367
Australian impact structure	Northern Territory	600	545 (est.)	25°33′S 131°23′E / 25.550°S 131.383°E
Azuara	Azuara, Spain	35-40	30-40	41°07′N 0°13′W / 41.117°N 0.217°W
Bedout	Western Australia (offshore)	250	250	18°S 119°E / 18°S 119°E
Bow City	Alberta	8.0	70	50°25′N 112°16′W / 50.417°N 112.267°W
Bowers crater[17]	Ross Sea, Antarctica	100	3-5[17][18][19]	71°12′S 176°00′E / 71.2°S 176°E
Charity Shoal Crater	Ontario	1.2	<470	44°2′15″N 76°29′37″W / 44.03750°N 76.49361°W
Cooper Basin[20]	South Australia/Queensland	80-160	300 (est.)	Impact center unknown
Corossol	Quebec	4.0	<470	50°03′N 66°23′W / 50.050°N 66.383°W
Decorah crater[21]	Iowa, USA	5.6	470	43°18′49.73″N 91°46′20.04″W / 43.3138139°N 91.7722333°W
Duolun[22]	Hebei/Inner Mongolia, China	70-170	129 ± 3	42°3′N 116°15′E / 42.050°N 116.250°E
East Warburton Basin	South Australia	200+	300-360[23]	28°00′S 140°30′E / 28°S 140.5°E
Eltanin impact	Pacific Ocean	35?	2.5	57°47′S 90°47′W / 57.783°S 90.783°W
Fried Egg structure[24]	Atlantic Ocean	6.0	17
Gatun structure	Panama	3.0	20	09°05′58″N 79°47′22″W / 9.09944°N 79.78944°W
Gnargoo[25]	Australia	75	<300	24°48′24″S 115°13′29″E / 24.80667°S 115.22472°E
Guarda	Portugal	30	200	40°38′N 07°06′W / 40.633°N 7.100°W
Ishim impact structure[26]	Akmola Region, Kazakhstan	300	460-430[27]	52°0′N 69°0′E / 52.000°N 69.000°E
Jeptha Knob	Kentucky, USA	4.3	425	38°11′N 85°07′W / 38.183°N 85.117°W
Kebira	Gilf Kebir, Egypt	31	100	24°40′N 24°58′E / 24.667°N 24.967°E
Lake Tai	Jiangsu, China	65	375	31°14′N 120°8′E / 31.233°N 120.133°E
Mahas	Northern, Sudan	2.8	?	20°01′53″N 30°13′40″E / 20.03139°N 30.22778°E
Maniitsoq crater	Greenland	100	3000	65°15′N 52°15′W / 65.250°N 52.250°W
Nastapoka (Hudson Bay) arc	Quebec, Canada	450	?	57°00′N 78°50′W / 57.000°N 78.833°W
Panther Mountain	New York, USA	10	375	42°03′N 74°24′W / 42.050°N 74.400°W
Praia Grande[28]	São Paulo (Brazil), (offshore)	20	84	25°39′S 45°37′W / 25.650°S 45.617°W
Ramgarh	Rajasthan, India	3.0	?	25°20′16″N 76°37′29″E / 25.33778°N 76.62472°E
Ross crater	Ross Sea, Antarctica	600?	38?[18]	77°30′S 178°30′E / 77.5°S 178.5°E
Rubielos de la Cérida	Aragon, Spain	80x40	30-40	25°20′56″N 76°37′29″E / 25.34889°N 76.62472°E
Saqqar[29]	Saudi Arabia	34	70-410	29°35′N 38°42′E / 29.583°N 38.700°E
Shiva crater	India (offshore)	500	65	18°40′N 70°14′E / 18.667°N 70.233°E
Silverpit	North Sea near England	8.0	60 ± 15	54°14′N 1°51′E / 54.233°N 1.850°E
Snows Island (Johnsonville)	South Carolina, USA	11	?	33°49′N 79°22′W / 33.817°N 79.367°W
Temimichat[30]	Mauritania	0.7	?	24°15′N 9°39′W / 24.250°N 9.650°W
Toms Canyon	New Jersey, USA	22	35	39°08′N 72°51′W / 39.133°N 72.850°W
Vichada Structure	Colombia	50	?	4°30′N 69°15′W / 4.500°N 69.250°W
Victoria Island structure	California, USA	5.5	37-49	37°53′24″N 121°32′05″W / 37.889925°N 121.534672°W
Weaubleau-Osceola	Missouri, USA	15-20	325 ± 15	37°59′N 93°38′W / 37.983°N 93.633°W
Wembo-Nyama ring structure[31][32]	DR Congo	36-46	60?	3°37′52″S 24°31′07″E / 3.63111°S 24.51861°E
West Warburton Basin	South Australia	100	300-360
Wilkes Land crater	Wilkes Land, Antarctica	480	250-500	70°S 120°E / 70°S 120°E

The Decorah crater has been proposed as being part of the Ordovician meteor event.^[33] The age of Silverpit and the confirmed Boltysh crater (65.17 ± 0.64 Ma), as well as their latitude, has led to the speculative hypothesis that there may have been several impacts during the KT boundary.^[34][35]

The Rubielos de la Cérida and Auzara impact structures of 30-40 Ma have been considered to be companion events.^[36]

The Eltanin impact has been confirmed (via an iridium anomaly and meteoritic material from ocean cores) but, as it fell into the Pacific Ocean, no crater was formed.

Craters larger than 100 km in the Phanerozoic (after 541 Ma) are notable for their size as well as for the possible coeval events associated with them especially the major extinction events.

For example, the Ishim impact structure^[26] is conjectured to be bounded by the late Ordivician-early Silurian,^[27] the East Warburton Basin has been linked to the Late Devonian extinction,^[23] both Bedout and the Wilkes Land crater have been connected to the severe Permian–Triassic extinction event,^[37][38] while the consensus is the Chicxulub impact caused the Cretaceous–Paleogene extinction event.

However, other extinction theories employ coeval periods of massive volcanism such as the Siberian Traps.

Mistaken identity

Some geological processes can result in circular or near-circular features that may be mistaken for impact craters. Some examples are calderas, sinkholes, glacial cirques, ring dikes, salt domes, and others. Conversely, an impact crater may originally be thought as one of these geological features, like Meteor crater (as a caldera) or Upheaval Dome (as a salt dome). The presence of shock metamorphism and shatter cones are important criteria in favor of an impact interpretation.

• 

  Crater Lake, Oregon (a caldera)

• 

  Great Blue Hole, Belize (a sinkhole)

• 

  Verdi Lake (a glacial cirque)

• 

  Ring dike on Pawtuckaway State Park

• 

  Salt domes on Melville Island

See also

• Impact craters
• Impact events
• List of impact craters on Earth
• List of meteor air bursts
• Earth Impact Database
• Impact Field Studies Group
• Tollmann's hypothetical bolide
• Traces of Catastrophe book from Lunar and Planetary Institute - comprehensive reference on impact crater science

References

1. Whitehouse, David (2003-06-23). "Space impact 'saved Christianity'". BBC News. British Broadcasting Corporation. Retrieved 2009-09-10.
2. Sandra Blakeslee. "Ancient Crash, Epic Wave".
3. Master, S. (2002) Umm al Binni lake, a possible Holocene impact structure in the marshes of southern Iraq: Geological evidence for its age, and implications for Bronze-age Mesopotamia. In: Leroy, S. and Stewart, I.S. (Eds.), Environmental Catastrophes and Recovery in the Holocene, Abstracts Volume, Department of Geography, Brunel University, Uxbridge, West London, UK, 29 August - 2 September 2002, pp. 56–57
4. Stevens, G, I Spooner, J Morrow, P Pufahl, R Raeside, RAF Grieve, CR Stanley, SM Barr, and D McMullin (2008) Physical evidence of a late-glacial (Younger Dryas?) impact event in southwestern Nova Scotia. Atlantic Geology. 44:42.
5. "The enigmatic Zerelia twin-lakes (Thessaly, Central Greece): two potential meteorite impact Craters". Solid Earth Discussions 5: 1511–1573. 2013. Bibcode:2013SolED...5.1511D. doi:10.5194/sed-5-1511-2013.
6. Heinrich, P.V. (2003) Possible Meteorite Impact Crater in St. Helena Parish, Louisiana. Search and Discovery Article. no. 50006. American Association of Petroleum Geologist, Tulsa, Oklahoma. Retrieved March 27, 2011.
7. Cannon, P.J. (1977) Meteorite impact crater discovered in central alaska with landsat imagery, Science, 1977 Jun 17;196(4296):1322-4.
8. Ned Rozell (2008) The mystery of mammoth tusks with iron fillings
9. Harris, R. S.; Schultz, P. H.; Zárate, M. A. (2007) La Dulce Crater: Evidence For A 2.8 Km Impact Structure In The Eastern Pampas Of Argentina, 38th Lunar and Planetary Science Conference
10. Povenmire H., Liu W. and Xianlin I. (1999) "Australasian tektites found in Guangxi Province, China", 30th Annual Lunar and Planetary Science Conference, Houston, March 1999.
11. H. Povenmire, R.S. Harris, and J.H. Cornec (2011), The New Central American Tektite Strewn Field, 42nd Lunar and Planetary Science Conference (2011)
12. Goff, James; et al. (2010). "Analysis of the Mahuika comet impact tsunami hypothesis". Marine Geology 271 (3/4): 292–296. doi:10.1016/j.margeo.2010.02.020.
13. Bourgeois, J., and R. Weiss (2009) 'Chevrons' are not mega-tsunami deposits; a sedimentologic assessment. Geology. 37(5):403-406.
14. Pinter, N., and S.E. Ishman, S.E. (2008). Impacts, mega-tsunami, and other extraordinary claims. GSA Today. 18(1):37.
15. Glass B.P. and Pizzuto J.E. (1994) "Geographic variation in Australasian microtektite concentrations: Implications concerning the location and size of the source crater," J of Geophysical Research, vol 99, no E9, 19075-19081, Sept 1994.
16. Hartung J. and Koberl C. (1994) "In search of the Australasian tektite source crater: the Tonle sap hypothesis", Meteoritics.
17. "Space impact clue in Antarctica".
18. L. P. Hrjanina (Khryanina). "Once again about Kainozoic meteorite structures in the Ross Sea, Antarctica" (PDF).
19. Gerard-Little, P., Abbott, D., Breger, D. and Burckle, L (2006). "Evidence for a Possible Late Pliocene Impact in the Ross Sea, Antarctica".
20. UQ Researcher Discovers Giant Asteroid Impact
21. U.S. Geological Survey. "Iowa Meteorite Crater Confirmed". Retrieved 7 March 2013.
22. Wu Siben. "Geologic feature of the Duolun impact crater".
23. Stephen Luntz. "Huge Asteroid Impact Identified".
24. Amos, J (2009) 'Fried Egg' may be impact crater BBC News.
25. R. Iaskty and A. Glikson (2005). "Gnargoo: a possible 75 km-diameter post-Early Permian – pre-Cretaceous buried impact structure, Carnarvon Basin, Western Australia", Australian Journal of Earth Sciences, Vol 52, 2005
26. Frank Dachille. "Frequency of the formation of large terrestrial impact craters".
27. Zeylik B. S.; Seytmuratova E. Yu, 1974: A meteorite-impact structure in central Kazakhstan and its magmatic-ore controlling role. Doklady Akademii Nauk SSSR: 1, Pages 167-170
28. A. P. Crósta1, M.A.R. Vasconcelos (2013). Update On The Current Knowledge Of The Brazilian Impact Craters.
29. Kenkmann, T., Afifi, A. M., Stewart, S. A., Poelchau, M. H., Cook, D. J. and Neville, A. S. (2015), Saqqar: A 34 km diameter impact structure in Saudi Arabia. Meteoritics & Planetary Science, 50: 1925–1940.
30. A. P. Rossi; A. Baliva & E. Piluso (2003). "New Evidences of an Impact Origin for Temimichat Crater, Mauritania" (PDF). Lunar and Planetary Science (Lunar and Planetary Institute). XXXIV.
31. G. Monegato; M. Massironi & E. Martellato (2010). "The Ring Structure of Wembo-Nyama (Eastern Kasai, R.D. Congo): A Possible Impact Crater in Central Africa" (PDF). Lunar and Planetary Science (Lunar and Planetary Institute) XLI.
32. "Ring may be giant 'impact crater'". BBC News. 2010-03-10. Retrieved 2010-05-08.
33. Vastag, Brian (18 February 2013). "Crater found in Iowa points to asteroid break-up 470 million years ago". Washington Post. Retrieved 19 February 2013.
34. Double space strike 'caused dinosaur extinction' http://www.bbc.co.uk/news/science-environment-11112417
35. Jolley D., Gilmour I., Gurov E., Kelley S., Watson J. (2010) Two large meteorite impacts at the Cretaceous-Paleogene boundary Geology September 2010, v. 38, pp. 835–838, doi:10.1130/G31034.1
36. Ernstson, K., Claudin, F., Schüssler, U. & Hradil, K. (2002): The mid-Tertiary Azuara and Rubielos de la Cérida paired impact structures (Spain) - Treb. Mus. Geol. Barcelona, 11, 5 - 65.
37. Becker L., Shukolyukov A., Macassic C., Lugmair G. & Poreda R. 2006. Extraterrestrial Chromium at the Graphite Peak P/Tr boundary and in the Bedout Impact Melt Breccia. Lunar and Planetary Science XXXVII (2006), abstract # 2321.PDF
38. Gorder, Pam Frost (June 1, 2006). "Big Bang in Antarctica – Killer Crater Found Under Ice". Ohio State University Research News.

External links

• Earth Impact Database – List of confirmed earth impact sites at the Planetary and Space Science Centre, University of New Brunswick
• Impact Database (formerly Suspected Earth Impact Sites list) maintained by David Rajmon for Impact Field Studies Group, USA